GARY PADGETT'S MONTHLY GLOBAL TROPICAL CYCLONE SUMMARY OCTOBER, 2000 (For general comments about the nature of these summaries, as well as information on how to download the tabular cyclone track files, see the Author's Note at the end of this summary.) *********************************************************************** OCTOBER HIGHLIGHTS --> Western Atlantic subtropics very active --> Significant typhoon rakes Philippines and Taiwan --> First North Indian Ocean cyclones of year develop *********************************************************************** ***** Feature of the Month for October ***** ATLANTIC SUBTROPICAL SYSTEMS OF 2000 (Part 1) ------------------------------------ This is Part 1 of a three-part feature detailing cyclonic systems of 2000 in the Atlantic which were either subtropical storms or depressions or else exhibited some of the features of subtropical cyclones. A few months back I asked David Roth if he would consider putting together such an article and he agreed to do so. David is a native of south Florida, a graduate of Florida State University, and is currently employed as a meteorologist at the Hydrometeorological Prediction Center in Maryland. David has a special interest in hybrid and subtropical cyclones and has been spending a lot of time the past few months poring over old weather maps and articles searching for "subs" for possible inclusion in the Atlantic "best track" database when the on-going re-analysis of the database reaches the latter part of the 20th century. Some explanations and a few words of caution are in order first, however. There is no generally agreed-upon, widely accepted, specific definition of exactly what constitutes a subtropical cyclone. The definition of a subtropical cyclone in TPC/NHC's on-line glossary reads: "a low-pressure system that develops over subtropical waters that initially has a non-tropical circulation but in which some elements of tropical cyclone cloud structure are present." The issue of non-frontality is not addressed in that definition, but seems to be a sort of "acid test" which is usually applied by NHC before officially recognizing the existence of a subtropical cyclone (especially storm). As I've already written in the discussion of Tropical Storm Leslie below, NHC is extremely conservative about using the subtropical classification operationally, and only a little less so in admitting subtropical storms into the "best track" file after the fact. On the other hand, David seems to employ a fairly liberal definition of a subtropical cyclone, so there are some differences between David's listing of subtropical systems and the ones that NHC has officially recognized as subtropical depressions or storms for at least a portion of their tracks. In this part I am going to include David's table of subtropical systems with appropriate comments as to how NHC has classified some of the systems in question. Also, I have included David's write-ups for two October systems below in the section covering Atlantic basin activity. Part 2 (November summary) will discuss the named tropical cyclones which in David's opinion exhibited subtropical cyclone characteristics for a portion of their lives--an opinion not necessarily shared in every case by the NHC specialists. Part 3 (December summary) will include David's write-ups for the remaining subtropical cyclones of 2000. The introduction David wrote to his article follows: The subtropical cyclone production in the Atlantic Basin this year has been exceptional. Eleven cyclones have entered the subtropical stage, nearly triple the long-term average of 3.7 per year. This is up sharply from 1999, when only five developed, and makes it the most productive year in the Atlantic since 1984 (when there were 9), and the most active of the past 50 years. Persistent blockiness in the Atlantic and eastern North America led to a high number of cutoff LOWS, which in many cases ultimately became subtropical. Three formed from tropical cyclones when either cool, dry air entered near the surface, or they became coupled with upper-tropospheric LOWS. Two contained hurricane force winds while still subtropical (Florence and Gordon). Three of these systems made landfall in the United States: subtropical cyclones III, VI (Gordon), and IX (Leslie). The table below lists their duration (and designations) while subtropical. Roman numerals were chosen similarly to the older, monthly cyclone discussions published in _Monthly Weather Review_ from the 1870s into the 1950s. (Numbers in parentheses following the storm designation refer to explanatory notes below.) I. Subtropical Depression May 19-25 II. Alberto (1) August 14-16 III. Subtropical Storm (2) August 28-30 IV. Subtropical Depression September 10-11 V. Florence (3) September 10-12 VI. Gordon (1) September 17-18 VII. Helene (1) September 24-25 VIII. Subtropical Storm (2) September 30-October 3 IX. Leslie (3) October 4-8 X. Michael (3) October 14-17 XI. Subtropical Storm (4) October 25-28 (1) The official NHC "best tracks" do not treat any portion of Alberto, Gordon, or Helene as subtropical. In general, once a tropical cyclone has been named, NHC treats it as a tropical system through- out the remainder of its life--both operationally and in post- analysis--even if at some point it exhibited some subtropical features. (2) According to Jack Beven, these two systems possibly could qualify as subtropical storms pending a careful analysis of all the available data. For the time being they should be regarded as possible subtropical storms. (3) Subtropical portions of the tracks of Florence, Leslie, and Michael are designated in the "best tracks" for these cyclones. The dates of their subtropical phases, however, might not necessarily agree with those David has assigned above. (4) This storm has already been officially recognized as a subtropical storm by TPC/NHC. *********************************************************************** ACTIVITY BY BASINS ATLANTIC (ATL) - North Atlantic Ocean, Caribbean Sea, Gulf of Mexico Activity for October: 2 tropical storms 1 hurricane 1 subtropical storm 1 hybrid (possibly subtropical) storm NOTE: Much of the information presented below was obtained from the TPC/NHC discussion bulletins issued with every regular advisory. All references to sustained winds imply a 1-min averaging period unless otherwise noted. Atlantic Tropical Activity for October -------------------------------------- An active October followed on the heels of a very active September in the Atlantic basin. Three of the September tropical cyclones were still active as the month opened: Hurricane Isaac was beginning to transition into a vigorous extratropical cyclone in the North Atlantic, former Hurricane Joyce was rapidly weakening as it moved through the Windward Islands into the southeastern Caribbean Sea (where it dissipated on 2 October), and major Hurricane Keith was reaching its peak intensity in the northwestern Caribbean just off the southern Yucatan Peninsula. Keith subsequently stalled just offshore of northern Belize, weakened into a tropical storm and made landfall in Belize, later emerging into the Bay of Campeche and regaining hurricane intensity before making a final landfall in Mexico north of Tampico on 5 October. See the September summary for the full reports on these tropical cyclones. The western Atlantic subtropics became a beehive of storm activity during October. A gale center developed off the southeastern U. S. coast during the opening days of the month and exhibited some features of a subtropical cyclone. (Further discussion of this system can be found below.) Also during the first week of the month, a system from the Caribbean which dumped very heavy rainfall on portions of southern Florida developed into a subtropical depression and eventually into Tropical Storm Leslie just off the east coast of Florida. Around mid-month another non-tropical LOW developed into a subtropical storm and underwent a classic transformation into a warm-cored cyclone and became Hurricane Michael. About ten days after Michael's development, another subtropical storm developed just north of the Bahamas and made a valiant attempt to become what would have been Tropical Storm Oscar, but was unable to sustain persistent convection near the center. (A write-up of this storm can be found below.) Finally, as Hurricane Michael was racing toward Newfoundland, a tropical wave interacted with an upper-level trough southeast of Bermuda to produce the season's final tropical cyclone: Tropical Storm Nadine. Nadine became a 50-kt tropical storm as it headed northeastward into the central Atlantic ahead of a cold front. The official TPC/NHC tropical cyclone reports prepared by the Hurricane Specialists are now available for all of the 2000 Atlantic basin tropical cyclones. The reports are very interesting and informative, and links to them can be found at the following URL: . Since I am running so far behind schedule, and since I think it highly likely that just about every person who reads these summaries has access to the internet, I am going to trim down the amount of material I write about the remaining Atlantic cyclones--primarily including a few items of interest which are not mentioned in the official NHC reports. The short summaries of the two subtropical systems following the write-up of Tropical Storm Nadine were written by David Roth. A special thanks to David for all the material he prepared on the hybrid/subtropical systems. Tropical Storm Leslie (TC-16) 4 - 10 October ------------------------------ Tropical Storm Leslie was a weak storm of subtropical origin which formed just east of the northeastern Florida coast and moved unevent- fully northeastward across the Atlantic. Before being classified as a tropical cyclone public advisories were issued on the system as Subtropical Depression One. The official storm report on Leslie, prepared by James Franklin and Daniel Brown, can be found at the following URL: . I recommend that interested readers first connect to TPC/NHC's website and read James' and Daniel's report, which contains a tabular listing and plot of the analyzed "best track" as well as plots of meteorological information. One unusual facet of this tropical cyclone was the enormous damage caused by heavy rains in southern Florida during the pre-depression stage. A weak mid-level circulation associated with a tropical wave moved northwestward out of the Caribbean Sea and interacted with a stalled frontal boundary. Very heavy rains fell over portions of Miami-Dade and Broward counties. Several locations had 48-hour storm totals exceeding 380 mm and one spot in South Miami logged 445 mm. Three deaths were indirectly attributed to the flooding, and the estimated total damage figure was around $700 million of which $500 million were agricultural losses. It should be emphasized that the rainfall which led to the flooding occurred before a well-defined surface circulation had formed. No deaths or damage were caused by the system after it had become Subtropical Depression One and Tropical Storm Leslie. The designation of the LOW on 4 October as a subtropical depression marks the first time that public subtropical depression or subtropical storm advisories have been issued by TPC/NHC since a subtropical storm in April, 1992. However, several systems during the intervening years have been classified as subtropical cyclones for at least a portion of their tracks during post-storm analysis. In the spectrum of cyclone classifications the boundary between extratropical and subtropical cyclones is very broad and diffuse, and TPC/NHC prefers to be very conservative with the use of the subtropical cyclone classification. Many cyclones are "hybrids", i.e., they exhibit features of both tropical and extratropical cyclones, but not all hybrids are considered to be subtropical cyclones. TPC/NHC does not like to operationally classify a system as subtropical--unless there is a very special reason for doing so--in the interest of avoiding potential confusion among the public and media. As for admitting subtropical storms into the "best track" file after-the-fact (e.g., June, 1997, and October, 2000) the NHC specialists like to carefully study the available data to insure that a system was absolutely non-frontal--something which is often difficult to accomplish in real-time. The primary difference between the "best track" and the operational track for Leslie is one of intensity. Operationally, Leslie's MSW was never reported any higher than 35 kts, and the storm was downgraded to a tropical depression at 06/1800 UTC. However, based on a more thorough analysis of the available data, the "best track" shows the MSW reaching 40 kts at 06/0600 UTC and remaining at this value until extratropical transition at 1800 UTC on 7 October. After losing its tropical characteristics the extratropical system moved rapidly across the North Atlantic as a fairly weak gale until 10 October when it began to intensify once more. The "best track" indicates that the cyclone reached southwestern Ireland as a 60-kt storm around 10/1800 UTC. It is perhaps arguable as to whether Leslie ever really was a tropical cyclone. The system at best had only nominal tropical characteristics--the deep convection never really moved over the center and the strongest winds were located farther out from the center than is typical of most tropical cyclones. James Franklin's comments in the discussion bulletin at 1500 UTC on 5 October (when Leslie was named as a tropical storm) are very interesting and give insight regarding the issues which the forecaster is often confronted with: "Reconnaissance observations this morning show that the wind field of the subtropical depression has been contracting, with peak flight-level winds of 44 kts reported within 75 nm of the center; whereas yesterday they were about twice as far out, and there has also been more consistent convection in the vicinity of the circulation. While this is by no means a classic tropical cyclone, it has enough tropical characteristics, and wind, to be considered a tropical storm. It is worth remembering that nature produces a whole spectrum of different kinds of cyclones, and that they do not always neatly fit into the small number of classi- fications that we have available for use in our advisories." Hurricane Michael (TC-17) 14 - 22 October -------------------------- Hurricane Michael formed off the coast of northeastern Florida from a subtropical storm and eventually raced northeastward and briefly became a Category 2 hurricane on the Saffir/Simpson scale before merging with a cold front just south of Newfoundland. The official storm report on Michael, prepared by Stacy Stewart, can be found at the following URL: . I recommend that interested readers first connect to TPC/NHC's website and read Stacy's report, which contains a tabular listing and plot of the analyzed "best track" as well as plots of meteorological information. Michael's origins can be traced to an upper-level cold LOW which dropped southward and interacted with a stationary frontal boundary over the southeastern Bahamas. The LOW gradually acquired subtropical characteristics and became a subtropical depression at 1200 UTC on 15 October. The "best track" indicates that the depression had developed gale-force winds by 16/0000 UTC and hence had become a subtropical storm. Convection gradually increased around the center and the transition to a tropical storm is estimated to have occurred by 17/0000 UTC. However, the system was not operationally classified as a subtropical depression or storm; instead, it was treated as a non-tropical LOW and gale warnings were included in the High Seas Bulletins. The first advisory on Tropical Depression 17 was issued at 17/0000 UTC and the system was upgraded to Tropical Storm Michael six hours later. Both the operational track and analyzed "best track" agree, however, that Michael reached hurricane intensity at 1800 UTC on the 17th, and the two are in close agreement from that point forward with regard to intensity. The storm had intensified to 75 kts by 1800 UTC on the 18th, but then weakened to 65 kts at 19/0600 UTC. As Michael raced toward Newfoundland a ship in the eastern eyewall reported sustained winds of 80 kts and a SLP of 965.5 mb, so the MSW was upped to 85 kts, making Michael a Category 2 hurricane. The highest flight-level wind measured by any US-based reconnaissance flight was 95 kts from a height of 450 m at 1755 UTC on 18 October. (A Canadian reconnaissance flight a few hours prior to landfall on the 19th measured a wind of 136 kts near the top of the boundary layer, but the cool (4 C to 10 C) and very stable air would likely have prevented those winds from reaching the surface.) Michael reached its peak intensity as it neared Newfoundland, but just a few hours before reaching the coast the storm merged with a cold front so technically was not a tropical cyclone as it made landfall. However, the storm still carried winds exceeding hurricane force. Sagona Island along Newfoundland's south coast measured winds to 69 kts with a peak gust of 93 kts and a pressure of 967.7 mb. Most of the island experienced winds of 50 kts and pressures around 975 mb as the storm roared across. Newfoundland, however, frequently experiences winds of that magnitude in association with North Atlantic extratropical cyclones and damage was reportedly light across the island. Tropical Storm Nadine (TC-18) 19 - 23 October ------------------------------ The final tropical cyclone of the 2000 Atlantic hurricane season formed over the open Atlantic southeast of Bermuda and moved rather uneventfully northeastward, becoming extratropical after a couple of days. The official storm report on Tropical Storm Nadine, prepared by Lixion Avila, can be found at the following URL: . I recommend that interested readers first connect to TPC/NHC's website and read Lixion's report, which contains a tabular listing and plot of the analyzed "best track" as well as plots of meteorological information. As Lixion's report points out, the formation of Nadine was triggered by the interaction of a tropical wave and an upper-level trough. The tropical wave instrumental in the development of Nadine seems to have been a wave first noted in the far eastern Atlantic around 5 October. The wave made its way slowly across the tropical Atlantic, battling shear and never showing any really serious signs of developing in the deep tropics. Around mid-month it encountered the upper-level trough, but several days were still required for the development of a surface depression. Another system worth mentioning was a tropical wave to the west of the precursor of Nadine. On 6 October a very well-defined and tightly-wound low-level circulation center became visible in association with this wave about 700 nm west of the Cape Verde Islands. It was undergoing shear and there was very little convection near the LLCC; hence, it was not classified as a tropical depression, but it was nonetheless somewhat impressive looking in visible imagery. Since Tropical Storm Nadine was a rather short-lived, uneventful storm, and since the official storm report covers it rather well, there isn't much else to write. The operational MSW estimates and the "best track" MSW values are in perfect agreement for the tropical storm phase of Nadine's life. At one point, when an eye-like feature became apparent in infrared and microwave imagery, there was an outside chance that Nadine might reach minimal hurricane intensity. This didn't happen, but if it had, the three-year period 1998-2000 would have had a total of 27 hurricanes--a new three-year record for hurricanes in the Atlantic basin. As it was, the 26 hurricanes observed over the three seasons tied the previous three-year record set in 1949-1951. Possible Subtropical Storm 30 September - 3 October -------------------------- As Joyce was recurving across the central Atlantic, and the major Hurricane Keith was approaching Belize, a closed 500-mb LOW (with -9 C air at that level) developed off the southeastern U. S. coast. Thunderstorm activity increased tremendously in this region, and a subtropical cyclone had developed over 31 C waters. A non-frontal LOW, with a large dry slot, the system moved up the Gulf Stream, reaching subtropical storm proportions overnight on the 30th/1st. The system became well removed from its thunderstorm activity on the 2nd while located between North Carolina and Bermuda. By the 3rd, the system had developed a definite frontal structure, instantly occluding off Nova Scotia. Based on ship reports, the peak winds during the possible subtropical phase of this system are estimated at 40 kts. NOTE: Jack Beven has indicated that all the available data for this system will be reviewed to see if it qualifies for inclusion in the "best track" database as a subtropical storm. Subtropical Storm 25 - 28 October ----------------- The final subtropical storm of the year formed from the end of an old frontal boundary north of the Greater Antilles. It retrograded westward to a position just northeast of the Bahamas and closed off a low-level circulation. Convection was plentiful with the system, and fronts became non-existent on the 25th. Right when it closed off, it instantly became a subtropical storm as winds of 35 kt were already present according to ship reports in its vicinity. The storm moved northward, with a definite dry slot around its western side for the next couple of days. It strengthened to a 55-kt cyclone early on the 28th as it was accelerating northeastward ahead of a cold front approaching the center of the circulation. It quickly became frontal by that evening, bombing to a 978-mb cyclone and occluding during its extratropical stage. NOTE: This storm has been officially classified as a subtropical storm and entered into the Atlantic "best track" database. A report on this system, authored by Jack Beven, is available at the following URL: . *********************************************************************** NORTHEAST PACIFIC (NEP) - North Pacific Ocean East of Longitude 180 Activity for October: 2 tropical storms NOTE: Much of the information presented below was obtained from the TPC/NHC discussion bulletins issued with every regular advisory (CPHC for locations west of 140W.) All references to sustained winds imply a 1-min averaging period unless otherwise noted. Northeast Pacific Tropical Activity for October ----------------------------------------------- The Northeast Pacific basin on the average sees two tropical storms develop during the month of October with one reaching hurricane force. This year there were two named storms in October but neither became a hurricane. Tropical Storm Olivia formed early in the month south of Manzanillo, Mexico, and moved slowly generally in a westward to west- northwestward direction for about a week, reaching a peak intensity of 55 kts twice. Late in the month, minimal Tropical Storm Paul formed far to the south of Baja California and followed a westward track for four days at an unusually low latitude: the complete track remaining south of 12N. The write-ups for Tropical Storms Olivia and Paul were written by John Wallace of San Antonio, Texas. A special thanks to John for writing the summaries of these two cyclones. Tropical Storm Olivia (TC-17E) 2 - 10 October ------------------------------- Olivia was one of the few NEP storms of 2000 whose formation was not tied to any tropical wave. Intermittent, strong convection off the west coast of Central America flared up strongly on 29 September and had consolidated into a tropical LOW by the 30th. The LOW organized steadily as it tracked westward; its cloud signature improved enough to warrant its upgrade to Tropical Depression Seventeen-E at 1500 UTC on 2 October, a move that was supported by ship reports. The depression's center at this time was located roughly 250 nm south-southeast of Manzanillo, Mexico. The small tropical cyclone tracked slowly west-northwestward in the easterly flow south of a mid-level ridge in a largely favorable synoptic environment. The depression intensified steadily despite some shear, and its organization improved enough to warrant its upgrade to Tropical Storm Olivia at 0900 UTC on 3 October, albeit with some reluctance based on limited data. Even with the moderate shear, Olivia intensified quickly and reached its peak estimated MSW of 55 kts and CP of 994 mb at 2100 UTC on the 3rd, a mere 12 hours after its upgrade. An SSM/I overpass indicated the formation of a partial eyewall, an event which was supported by satellite imagery suggesting an incipient eye. Intensification to hurricane intensity was forecast. This did not materialize, however, and Olivia leveled off at its peak intensity for about two days. Olivia remained quasi-stationary for around 12-18 hours on the 4th about 225 nm south-southwest of Manzanillo while it was at its peak intensity. Persistent, stiff easterly shear finally took its toll on the 5th when a weakening trend began as the storm turned to the west-southwest. By 0900 UTC on the 6th, Olivia had weakened to minimal tropical storm strength with slow dissipation forecast. Tropical cyclones are nothing if not capricious, however, and Olivia was no exception. Beginning at 1500 UTC on the 6th, there was a second intensification trend as Olivia turned again to the west-northwest. Satellite and model data suggested that Olivia's second wind, so to speak, was due to weakened wind shear. Re-intensification was slow and uneven though, as convection redeveloped over the center only to weaken or get sheared off repeatedly. Conflicting satellite data added to the forecasters' problems. Nevertheless, Olivia re-attained its peak intensity of 55 kts and a 994 mb CP for a second time at 2100 UTC on 7 October when it was centered approximately 400 nm south-southwest of Cabo San Lucas on the tip of the Baja California peninsula. It was an ephemeral achievement; another weakening trend began immediately after its second peak. Shear increased, and there were the first indications of stable air entrainment. The storm's track turned slightly more to the northwest as it reached the periphery of the ridge to its north. Olivia weakened steadily through the 8th, and had dropped below tropical storm strength by 0900 UTC on the 9th as it entered cooler waters. A possible threat to the Baja peninsula was forecast as a trough approached, but Olivia was not expected to survive long enough to fulfill it. Such was the case, and the last advisory was issued on the convection-free whorl at 0900 UTC on the 10th placing the dissipating cyclone about 500 nm west-southwest of Cabo San Lucas. A notable characteristic of Tropical Storm Olivia was its small size. The radii of gale-force winds never exceeded 75 nm, and throughout most of the storm's life they ranged from 50-60 nm. This is a size range similar to that of 1999's Tropical Storm Emily in the Atlantic. There were no known casualties associated with Olivia. The very weak remnant LOW eventually moved northeastward across the Baja peninsula and portions of the American Southwest. Some localities received up to 75 mm of rain which resulted in isolated flash flooding. The official storm report on Tropical Storm Olivia, prepared by Stacy Stewart, is available on TPC/NHC's website at the following URL: . One item in Stacy's report which differs from John's account above concerns the origin of Olivia. According to the NHC report, Olivia's development was associated with a wave which left the coast of western Africa on 16 September. After entering the Eastern Pacific the wave was hampered somewhat by major Hurricane Keith to its north and likely was difficult to follow for a few days until Keith had weakened and its influence declined. One minor difference was noted between the operational warnings and "best track": operationally Olivia was upgraded to a tropical storm at 03/0600 UTC--in post-analysis it was determined that the system had reached tropical storm intensity six hours earlier. Tropical Storm Paul (TC-18E) 25 - 29 October ----------------------------- Like Olivia before it, the formation of Tropical Storm Paul did not appear to be related to a tropical wave. A disturbance in the ITCZ west of Central America consolidated into a tropical LOW on 21 October. The LOW tracked steadily westward at a low latitude for several days until its organization was sufficient to warrant its upgrade to Tropical Depression Eighteen-E at 2100 UTC on 25 October when it was approximately 750 nm south of Cabo San Lucas. It is worth noting that the first advisory indicated the disturbance might have been a tropical storm the night prior to its upgrade before shear took its toll; a QuickScat pass at 1300 UTC on the 25th indicated 35-40 kt winds. The primary steering factor for the depression was a low- to mid-level ridge to the north which kept the system on a general westward track throughout its lifetime. Stiff north to northwesterly shear initially hindered the depression. Even so, its organization increased enough overnight to justify its upgrade to Tropical Storm Paul at 1500 UTC on 26 October when it was located about 800 nm south-southwest of Cabo San Lucas. Continued shear made life difficult for Paul as it tracked westward and the cyclone never intensified beyond minimal tropical storm strength. Paul maintained a 35-kt MSW for less than two days; the lowest CP of 1003 mb was reached at 0300 UTC on 27 October and was maintained for 12 hours. The storm took a brief west-northwest jog on the 27th as a shortwave trough passed to the north, then turned back to the west as the ridge to its north strengthened again. Throughout its life as a tropical storm Paul remained in a sheared state; contrary to forecasts, upper-level westerlies did not decrease over the system. Paul weakened to a depression at 0900 UTC on the 28th. The tropical cyclone quickly disintegrated, and at 0300 UTC on 29 October the last advisory was issued on the poorly-defined system located roughly 1300 nm southwest of Cabo San Lucas. There were no known casualties or other damage associated with Paul. The official storm report on Tropical Storm Paul, prepared by Miles Lawrance, is available on TPC/NHC's website at the following URL: . There were two minor differences noted between the operational warnings and "best track". Advisories were begun on TD-18E at 25/1800 UTC--the "best track" begins the depression stage twelve hours earlier at 0600 UTC. Also, the highest MSW given in any advisory was 35 kts, but the "best track" assigns a peak MSW of 40 kts at 26/1800 UTC. *********************************************************************** NORTHWEST PACIFIC (NWP) - North Pacific Ocean West of Longitude 180 Activity for October: 2 tropical storms ** 2 typhoons ** - one of these was treated as a tropical storm only by JTWC, and another is included based upon Mark Lander's assessment that it reached tropical storm intensity NOTE: Most of the information on each cyclone's history presented in the narrative will be based upon JTWC's advisories, and references to winds should be understood as a 1-min avg MSW unless otherwise noted. However, in the accompanying tracking document I have made comparisons of coordinates with JMA (Japan) and the Philippines (PAGASA) when their positions differed from JTWC's by usually 40-50 nm or more. A special thanks to Michael V. Padua, owner of the Typhoon 2000 website, for sending me the PAGASA and JMA tracks. In the title line for each storm I plan to reference all the cyclone names/numbers I have available: JTWC's depression number, the JMA-assigned name (if any), JMA's tropical storm numeric designator, and PAGASA's name for systems forming in or passing through their area of responsibility. Northwest Pacific Tropical Activity for October ----------------------------------------------- In marked contrast to August and September, the Northwest Pacific basin was much quieter in October, at least until the closing days of the month when two typhoons formed. Typhoon Yagi threatened Taiwan but ran into an unfavorable environment and dissipated between Taiwan and Okinawa. (Note: JMA did not classify Yagi as a typhoon, but PAGASA did upgrade the storm to typhoon status.) Whereas Yagi formed as a small, TUTT cell-induced system in the northern edge of the tropics, Typhoon Xangsane formed as a monsoon depression very deep in the tropics east of Mindanao. Xangsane crossed Luzon and later brushed Taiwan and was responsible for several fatalities and significant damage in both countries. In addition to the named cyclones there were two other systems which are discussed below. Tropical Storm 28W was a weak tropical cyclone which roamed the western South China Sea for over a week early in the month. JMA classified this system as a tropical depression only, but synoptic observations in the 35-40 kt range seem to support JTWC's decision to upgrade the system to a tropical storm. Also, I have included some information supplied by Mark Lander on another very small TUTT cell-induced LOW which he considers to have been an unnamed, unnumbered tropical storm. I have dubbed this cyclone with the Greek letter "Xi" for identification purposes. Finally, another tropical depression (31W) formed on the final day of October east of Mindanao almost exactly where Typhoon Xangsane had taken shape a few days earlier. This system developed into Typhoon Bebinca and followed a track across the central Philippines almost identical to that taken by the earlier storm. Bebinca will be covered in the November summary. Tropical Storm (TC-28W) 6 - 14 October ------------------------ Tropical Storm 28W was a relatively weak system which roamed the western South China Sea for a week in early October. JTWC classified the system as a tropical storm on 8 and 9 October and again very briefly before it dissipated on the 13th, but JMA treated the LOW as a tropical depression throughout its lifetime: hence, no name was assigned. The cyclone also remained to the west of PAGASA's AOR so never received a name from that agency. A persistent although disorganized area of convection was located in the Sulu Sea early on 4 October. Vertical shear was weak and the area was located beneath a ridge axis. As the day progressed convection developed farther to the west--to the southwest of Palawan Island--with improving organization. A LLCC was evident and JTWC assigned a Fair development potential rating to the disturbance. By early on 6 October the broad, poorly-defined LLCC was located about 200 nm off the Vietnamese coast and, with moderate upper-level easterlies over the area, appeared to be weakening, so the development potential was downgraded to Poor. However, as the day progressed animated satellite imagery indicated an increase in convective organization and a ship in the area reported an observation of 30-kt winds, so at 1800 UTC JTWC initiated warnings on TD-28W, located about 100 nm east-northeast of Cam Ranh Bay, Vietnam. The MSW was estimated at 30 kts, and the depression was initially forecast to move westward and inland without further strengthening. Visible pictures on the 7th, however, revealed that the depression's center was farther east than previously analyzed, resulting in a relocation of about 65 nm to the east of the previous warning position. The depression subsequently drifted slowly in a general eastward direction, gradually curving to the north on the 8th. As early as 0600 UTC on the 7th some satellite intensity estimates were reaching 35 kts and by 08/0600 UTC had reached 45 kts. This, in conjunction with a land observation of 35-kt winds (WMO 59995), led to JTWC's upgrading the depression to a tropical storm at 0600 UTC. The cyclone was still experiencing moderate easterly vertical shear, resulting in a fully-exposed LLCC with deep convection sheared around 40 nm to the west. (JMA had classified the system as a tropical depression at 1800 UTC on the 7th but never upgraded it to a tropical storm.) The weak storm drifted slowly northward on the 8th, then began to turn to the northwest on the 9th as a low- to mid-level ridge began to build to the northeast. The MSW was increased to the peak value of 40 kts at 08/1800 UTC based upon satellite intensity estimates of 35 and 45 kts. An increase in convection had occurred near the LLCC during the night. The peak intensity of 40 kts was maintained for about 30 hours. Moderate shear remained over the cyclone as it moved slowly northward and northwestward, and the center was partially-exposed. A synoptic ship report of 40-kt winds was received sometime before 09/0600 UTC, confirming the MSW estimate. By 1800 UTC on 9 October the center of the weak tropical storm was located about 215 nm east-southeast of Da Nang, Vietman, and moving northwestward at 6 kts. Satellite current intensity estimates were still ranging from 35 to 55 kts, but the center had become exposed with the LLCC displaced about 75 nm to the east of the deep convection. The majority of the convection associated with the system had moved over the Vietnamese coast. A ship located approximately 50 nm west-southwest of the center reported 35-kt winds (10-min avg) from the west-northwest with an attendant SLP of 999.5 mb. Again, on the 10th, the first visible pictures resulted in a relocation of the center. The 10/0000 UTC position was about 90 nm southwest of the previous warning position, and the storm was downgraded to a tropical depression. TD-28W was forecast to move inland and dissipate, but instead the system began to track northeastward under the steering influence of monsoon trough winds to its south. Over the next couple of days the weak depression drifted slowly generally in a northeastward direction, remaining a fully-exposed LLCC with little to no associated deep convection. This made the center very difficult to follow in night- time infrared imagery, and the track appears somewhat erratic. The estimated MSW, which had been decreased to 25 kts at 1200 UTC on 10 October, was bumped up slightly to 30 kts at 12/0000 UTC as micro- wave imagery revealed two cells of deep convection forming near the center. Dvorak intensity estimates began to slowly increase on the 12th--by 1200 UTC a new area of convection had developed over the estimated position of the LLCC. The depression was once more upgraded to a tropical storm at 0000 UTC on 13 October when the location of the center was estimated to be about 245 nm east-northeast of Da Nang. The exact location of the LLCC, however, was difficult to pinpoint. Convection covered the entire northern South China Sea and there was some evidence of multiple circulation centers. Satellite intensity estimates were 35 kts, and a strong band of convection had begun to organize to the north and east of the estimated center. The rejuvenated tropical storm had also turned toward the northwest and was forecast to make landfall along the east coast of Hainan Island. However, six hours later animated satellite imagery showed a decrease in the intensity of the convection and the LLCC was difficult to locate. JTWC once more downgraded the cyclone to a depression at 13/0600 UTC and issued the final warning, placing the dissipating center about 175 nm east- northeast of Da Nang. A secondary LLCC with some weak convection was noted about 150 nm to the south of the primary center but no further development was noted with this system. Tropical Cyclone "Xi" 15 - 19 October --------------------- The material presented on this system was gleaned from information sent to the author by Dr. Mark Lander of the University of Guam and from some STWO's issued by JTWC. The track prepared by Mark locates a small, weak circulation center about 475 nm east-southeast of Iwo Jima at 0000 UTC on 15 October. Over the next couple of days the system moved generally west-northwestward, passing approximately 50 nm south of Iwo Jima around 1200 UTC on the 16th. The area was first mentioned by JTWC in a STWO issued at 16/0600 UTC and was described as a fully-exposed LLCC with convection sheared southwest of the center and embedded in an inverted trough. Mark's track depicts the LOW reaching its point of recurvature about 50 nm west-northwest of Iwo Jima around 17/0000 UTC and thereafter turning to the north and later to the east. Mark's MSW estimate at this point is 30 kts, but the 17/0600 UTC STWO from JTWC indicates that the system had disspated. In Mark's opinion the system reached tropical storm intensity around 1200 UTC on the 17th at a point about 100 nm north-northwest of Iwo Jima and reached its peak intensity of 40 kts twelve hours later when it was centered 200 nm north of the island. That the system appeared better developed is evidenced by the issuance of a Formation Alert by JTWC at 18/0200 UTC. The remarks indicated that a 17/2030 UTC Quik- Scat pass showed 15-20 kt winds and troughing in the area, but also noted that the circulation might be too small for the satellite to resolve. The areal extent of the system was only about 100 nm and it was located on the end of a shear line. The small cyclone moved off to the east and had weakened to a depression (per Mark's track) by 1800 UTC on the 18th. JTWC cancelled the Formation Alert at 1400 UTC and reported that the system had begun to move rapidly eastward and was weakening under increasing vertical shear as it neared a cold front moving off Japan. By 19/0000 UTC the LOW had apparently been absorbed into the front about 300 nm northeast of Iwo Jima. Mark Lander elaborated a bit on the subject of these small, TUTT cell-induced tropical cyclones in the subtropics when he sent me the track. I thought that his remarks might be of interest to some readers so I am including them here verbatim: "I think these small tropical cyclones that develop in the subtropics in association with TUTT cells are important because of their very delimited and easily followed genesis that is clearly related to the forcing of the upper-level vortex on the distribution of convection, stability and wind shear. These types of small TCs tend to form in the northeast quadrant of the TUTT cell in pre-existing low-level easterly flow, unlike the majority of WESTPAC TCs that form in the monsoon trough. "The subject tropical storm formed only a few days before the next TUTT cell to move west across the WESTPAC basin produced another TC that became Typhoon Yagi. Images of Yagi forming in its TUTT cell environment look identical to images of the subject unnamed, unnumbered tropical storm at the same point of development in its TUTT cell environment. "TUTT cell-induced TC genesis in the subtropics of the WESTPAC basin is the closest thing that we have to what might be considered a 'wave in the easterlies.' As the incipient TC develops from its parent MCS, there is a brief stage where an inverted trough appears in the easterly flow. "Another rule of thumb that has emerged from a study of these small TUTT cell-induced TCs: they tend to peak after recurvature. Some of the more intense ones (like Yagi, which followed this guy by only a few days, and Jelawat in early August) keep moving westward and peak at typhoon (intensity) before recurvature. "A more thorough examination of a satellite picture archive like that of Jeff Hawkins at NRL Monterey might yield a more accurate best track, so my purpose here is simply to point out the existence of an unnumbered, unnamed tropical storm, and those really interested in following up, or doing more research, on it can use my best track as a reference for a more in-depth search." (Quote from personal e-mail received from Mark Lander.) Typhoon Yagi (TC-29W / STS 0019 / Paring) 21 - 28 October ------------------------------------------ Yagi: contributed by Japan, is the Japanese word for goat Typhoon Yagi was a compact typhoon which formed in the upper tropics about 200 nm southwest of Iwo Jima and traveled westward for several days in the general direction of northern Taiwan. As Yagi approached Taiwan it intensified rather quickly into a fairly intense typhoon (based upon JTWC warnings) and was forecast to strike the island, but it ran into an environment of vertical wind shear and drier air and began to steadily weaken. The storm eventually made a clockwise loop east of northern Taiwan as it dissipated. It should be pointed out that JMA never upgraded Yagi to a typhoon. At the warning time when JTWC's estimated MSW reached its peak value of 105 kts (24/1800 UTC), JMA's maximum 10-min avg wind estimate was only 55 kts. JMA did increase the 10-min avg wind to 60 kts at 25/0000 and 25/0600 UTC. However, PAGASA (which called the storm Paring) did upgrade Yagi to a 65-kt typhoon (10-min avg) at 24/0600 UTC and maintained that intensity until the storm moved out of their AOR after 25/0000 UTC. Yagi's beginnings can be traced to an area of convection which had developed by early on 20 October about 400 nm north-northeast of Guam. A partially-exposed weak LLCC could be seen in animated satellite imagery with persistent, isolated convection north of the center. The disturbance was embedded within an inverted trough with convergent flow displaced north and east of the center; vertical shear was light to moderate. The development potential was upgraded to Fair later in the day as convection increased in areal extent. A Formation Alert was issued at 0800 UTC on the 21st when the LLCC was centered approximately 325 nm south-southeast of Iwo Jima. The system had been moving rather rapidly westward under the steering influence of the subtropical ridge to the north. The initial warning on TD-29W was issued at 1800 UTC on 21 October and placed the center about 225 nm south-southwest of Iwo Jima or approximately 740 nm east-southeast of Okinawa. (JMA had classified the system as a tropical depression beginning at 0000 UTC.) TD-29W was moving rather quickly west-northwestward at 17 kts and was already near tropical storm intensity. JTWC upgraded the depression to a tropical storm on the second warning (22/0000 UTC) when satellite intensity estimates had reached 35 kts, and JMA did so six hours later, naming the system Yagi. Based upon JTWC warnings Yagi remained a minimal tropical storm for 24 hours after being upgraded as it sailed rather quickly toward the west. (JMA increased the maximum 10-min avg wind estimate to 40 kts at 1200 UTC.) The 1200 UTC warning from JTWC, while indicating that convection had consolidated around a small LLCC, also noted that a recent QuikScat pass had not been able to resolve a circulation center beneath the convection. JTWC increased the MSW to 45 kts at 23/0000 UTC with the small cyclone centered about 360 nm southeast of Naha, Okinawa. Yagi's forward motion had slowed to 9 kts by 1200 UTC and the MSW was upped to 60 kts at 1800 UTC. Satellite intensity estimates were 45 and 55 kts, but infrared imagery showed possible eye development. A 23/1228 UTC SSM/I pass depicted tightly curved convective bands with the deepest convection north of the system's center. JTWC upgraded Yagi to a typhoon at 0000 UTC on 24 October when the storm was located just under 200 nm south of Okinawa. Animated water vapor imagery indicated that a new outflow channel had formed on the north side of the system, thus supporting the increase in intensity. (PAGASA upgraded Yagi/Paring to a 65-kt typhoon at 0600 UTC but the storm was not considered a typhoon by JMA.) The storm continued to rapidly intensify and reached its peak estimated MSW (per JTWC's warnings) of 105 kts at 1800 UTC when it was centered approximately 215 nm east-southeast of Taipei and 20 nm south of Miyako Island.) The warning intensity was based upon satellite intensity estimates of 102 and 115 kts. Miyako Island (WMO 47927) reported sustained 28-kt winds, so Yagi was characterized by a very tight wind field. Satellite imagery revealed a 20-nm cloud-filled eye with the radius of 50-kt winds estimated to be only 25 nm. Gales covered an area less than 150 nm in diameter. Interestingly, before reaching its peak intensity, Yagi had been forecast to make landfall in Taiwan. But by the time the storm peaked, landfall was no longer forecast and the typhoon was expected to encounter vertical shear and begin to weaken quickly after about 24 to 36 hours. At 25/0000 UTC Miyako Island reported 10-min avg sustained winds of 59 kts with gusts to 78 kts. Some shearing was already beginning to affect Yagi and convection was weakening. The MSW was lowered to 90 kts at 0600 UTC with the cyclone moving north- northwestward at only 4 kts from a position 140 nm east of Taipei. The forecast weakening trend continued: by 0000 UTC on 26 October Yagi's winds were down to 75 kts, and JTWC downgraded the cyclone to a tropical storm at 1200 UTC. At 26/0000 UTC Yagi was located about 140 nm west of Okinawa and was tracking slowly eastward. The storm was located beneath 30-40 kt upper southwesterlies and cold, dry air was being entrained into the system. The strong shear began to decouple the convection from the LLCC, and the 1200 UTC warning noted that the convection appeared to be rotating anti-cyclonically if at all. Radar imagery also indicated a band of strong convection moving eastward without any rotation evident. The weakening Yagi approached to within about 40 nm of Naha before turning back to the west-southwest. At 27/0000 UTC the MSW was estimated at 45 kts by JTWC, but JMA downgraded Yagi to a dissipating depression and issued their last tropical cyclone bulletin on the system. Convection was sheared about 185 nm to the northeast of the LLCC. A building ridge over the East China Sea forced the sheared cyclone to the south and then back to the west as it dissipated, describing a clockwise loop in the process. JTWC downgraded Yagi to a tropical depression at 1200 UTC on the 27th when the LLCC was located about 125 nm southwest of Okinawa. At 28/0000 UTC a ship located about 55 nm south-southwest of the depression's center reported north- northwest winds of 26 kts. By this time there was no significant convection associated with the system. The final warning on Yagi was issued at 28/0600 UTC and placed the center with only 20-kt winds about 90 nm east of Taipei, Taiwan. Animation of visible satellite imagery revealed a vast stratocumulus deck with a convection-free, fully-exposed low-level circulation center. The author has received no reports of any casualties or damage associated with Typhoon Yagi. Typhoon Xangsane (TC-30W / TY 0020 / Reming) 25 October - 2 November --------------------------------------------- Xangsane: contributed by Lao People's Democratic Republic (Laos), is the Laotian word for elephant In contrast to Typhoon Yagi, which was a small, TUTT cell-induced system forming in the upper tropics, Typhoon Xangsane developed in the monsoon trough very deep in the tropics east of the southern Philippines. Although the storm developed into a typhoon of only moderate intensity (90 kts), it left a trail of death and destruction in the Philippines and Taiwan. An area of convection had developed by early on 24 October almost 300 nm southeast of Yap. A sudden burst of convection had appeared in satellite imagery and synoptic data indicated a weak LLCC embedded in the monsoon trough extending eastward from Mindanao. The disturbance moved westward with slowly increasing organization and pressure falls of 2 to 4 mb in the area. JTWC issued a Formation Alert at 0500 UTC on the 25th when the center was located about 75 nm south of Yap. Deep convection had begun to develop near the LLCC and the development potential was rated as Good. PAGASA classified the LOW as a tropical depression at 0200 UTC and initiated warnings, naming the depression Reming. JTWC issued the first warning on TD-30W at 25/1200 UTC with the center estimated to be about 140 nm northeast of Palau. The system was moving on a west-northwestward course from which it never significantly deviated until after it had crossed Luzon and recurved sharply to the north-northeast in the South China Sea. Deep convection continued to develop near 30W/Reming's center but organization of the convection proceeded somewhat slowly. PAGASA upgraded Reming to a 40-kt tropical storm at 0000 UTC on 26 October when the system was centered approximately 175 nm northwest of Palau. Both JTWC and JMA upgraded the system to a tropical storm at 0600 UTC with JMA assigning the name Xangsane (the second "elephant" of the year: the name of the first typhoon back in May--Damrey--is the Cambodian word for elephant). Tropical Storm Xangsane steadily intensified as it marched toward the central Philippines. Vertical shear was weak and the convection became increasingly intense and organized around the circulation center. MSW estimates had reached 55 kts from both JTWC and PAGASA by 1800 UTC, and JTWC upgraded Xangsane to a typhoon at 27/0000 UTC with the center located about 200 nm northeast of Surigao (on the extreme northern tip of Mindanao). PAGASA's 10-min avg wind estimate was 60 kts, but JMA's was somewhat lower at 50 kts. Xangsane/Reming continued to increase in intensity until it made landfall in extreme southeastern Luzon shortly before 1800 UTC. JTWC estimated the MSW at 75 kts (based on satellite intensity estimates of 65 and 77 kts), but PAGASA's and JMA's maximum 10-min avg wind estimates were 60 kts, just shy of typhoon intensity. The center of the cyclone passed just south of Catanduanes Island, up the Lagonoy Gulf and into southeastern Luzon. At 1800 UTC the center of Xangsane/ Reming was located approximately 135 nm east of Manila. This location is only 25 nm (45 km) northeast of Naga City where one of my "helpers", Michael Padua, lives. Although convection had continued to organize around the center, it weakened in the bands northwest of the eye as they rotated over Luzon. A SSM/I pass at 27/1310 UTC revealed a 30-nm round eye with excellent banding features. Also, animated water vapor imagery depicted good outflow above the storm. Michael Padua sent me a log of his personal observations as Reming passed over Naga City (which was in the eye of the typhoon). The maximum sustained wind Mike recorded was a north-northeast wind of 43 kts (80 kph) at 3:00 and 3:30 AM local time. This was before the eye reached Naga City around 4:00 AM when the winds began to diminish rapidly. The peak gust of 53 kts (98 kph) was recorded at 1:00 AM, although a nearby PAGASA station recorded a gust of 59 kts (108 kph) at 6:00 AM, after the eye had passed by. The minimum pressure recorded by Mike in the eye was 977 mb at 4:30 AM. Mike's complete Observations Log can be found at the following URL: By clicking on the "Show Graph" button one can view a very nice and informative graphical representation of the time histories of the pressure, sustained wind, and peak gusts which Mike recorded on his instruments. By using colored bars for pressure and two different colored lines for the two windspeed parameters, Mike has created a very impressive-looking and easy-to-read chart of his observations. Typhoon Xangsane/Reming crossed the southern portion of Luzon, passing about 80 km south of Manila around 0600 UTC on 28 October. The 28/0000 UTC observation from WMO 98440 indicated 40-kt sustained winds (10-min avg) and a SLP of 990.4 mb. The MSW had decreased to 55 kts by the time the center emerged into the South China Sea (around 1800 UTC). While the storm was still over Luzon, at 0600 UTC, a ship 75 nm to the northwest of the center reported sustained north- erly winds of 45 kts. Deep convection persisted near the center while the storm was over land. By 1800 UTC the center of Xangsane was over the South China Sea about 85 nm northwest of Manila and moving north- westward at 10 kts. The storm became quasi-stationary on the 29th about 200 nm northwest of Manila. The MSW remained at 55 kts but around 29/1200 UTC the convection had weakened due to some erosion by dry air in the western semicircle. However, by 1800 UTC the storm had re-intensified with a developing banding eye apparent, so Xangsane was upgraded once more to typhoon status with 65-kt winds. (JMA's maximum 10-min avg wind was 60 kts at this juncture, but both JMA and PAGASA upgraded the storm to a typhoon at 30/0000 UTC.) A TRMM pass at 29/1517 UTC depicted improving organization with a solid ring of eyewall convection. Xangsane reached its peak intensity of 90 kts (per JTWC) at 0000 UTC on 30 October. The storm was still quasi-stationary about 200 nm from Manila or about 360 nm south-southwest of the southern tip of Taiwan. (JMA's maximum 10-min avg wind for the storm's history was 75 kts from 30/0600 to 31/1200 UTC.) A ragged eye 28-nm in diameter was visible, and the typhoon exhibited excellent outflow in all quadrants. Convection over the northeastern quadrant more or less disappeared due to interaction with the west coast of Luzon, but a fulldisk infrared image showed a large feeder band extending from Malaysia into the center of Xangsane. By 1800 UTC on the 30th the storm was located approximately 65 nm west of Laoag on northwestern Luzon and was moving north-northeastward at 8 kts. An approaching upper-level trough caused the typhoon to accelerate toward the north-northeast and also increased the shear over the storm. At 31/1200 UTC the 30-nm diameter eye was centered about 65 nm south of the southern tip of Taiwan and was moving north-northeastward at 13 kts. By 1800 UTC on the 31st Xangsane was brushing the southeastern coast of Taiwan and had accelerated to 19 kts. The MSW had dropped to 80 kts (70 kts from JMA) and the typhoon was beginning to slowly transition into an extratropical storm. Typhoon Xangsane continued to slowly weaken and lose its tropical characteristics as it sped north-northeastward just off the east coast of Taiwan. The storm passed about 65 nm east of Taipei around 0000 UTC on 1 November and by 0600 UTC was only a minimal 65-kt typhoon located about 100 nm northeast of the city. (JMA at this point down- graded Xangsane to a 50-kt tropical storm.) JTWC downgraded the system to a tropical storm at 01/1200 UTC and issued their final warning at 1800 UTC. Xangsane was located about 100 nm southwest of the Japanese island of Kyushu (or about 375 nm east of Shanghai, China) and was racing northeastward at 37 kts. The rapidly weakening convection was being sheared northeast of the center and satellite imagery indicated significant entrainment of cooler, drier air with an extensive strato- cumulus field from southwest to northwest of the system. The by-now extratropical gale continued to move northeastward across southwestern Japan. The final position available to the author (from JMA's High Seas Bulletins) placed the LOW in the vicinity of Osaka at 0600 UTC on 2 November. A press report indicated that Typhoon Xangsane/Reming left at least 26 dead in the Philippines with 50 additional persons missing at the time of the report, most of these fishermen missing at sea. The storm caused 30,000 families to have to evacuate their homes and 100,000 persons were left homeless. Hundreds of homes were damaged due to flooding in Manila and nearby provinces. Total damage to property and crops was placed at 1.4 billion pesos, or $27.45 million. The Filipino Department of Agriculture reported that 275,672 hectares of rice paddies were flooded, resulting in an estimated loss of 112,211 tons of unmilled rice. In Taiwan Xangsane was reportedly the most destructive typhoon to strike the island since Typhoon Herb in 1996. The death toll reached at least 59 with 30 persons missing. In the northern port city of Keelung, 21 persons were drowned after being caught in buildings that flooded rapidly. Heavy rains triggered landslides near Taiwan, and schools and government offices in several cities and counties closed due to the storm. Flooding was reported to be the worst on Taiwan in 30 years. The Council of Agriculture estimated initial agricultural losses at $62.5 million. There was also an air disaster which was indirectly due to the typhoon. A Boeing 747 owned by Singapore Airlines crashed on takeoff from Taipei's Chang Kai Shek International Airport on 31 October with the loss of 82 lives out of the 179 on board. At the time of the crash Typhoon Xangsane was near the southern tip of the island and moving quickly north-northeastward. Winds at the airport were 37 kts from the north-northeast gusting to 56 kts, and visibility was 400 m in heavy rain. A subsequent investigation of the accident revealed that the flight crew mistakenly attempted takeoff on the wrong runway, one which was closed for repairs. The airplane struck some of the construction equipment while traveling at 140 kts, breaking the fuselage into three parts and igniting a large post-crash fire. More details on the accident can be found at the following website: *********************************************************************** NORTH INDIAN OCEAN (NIO) - Bay of Bengal and Arabian Sea Activity for October: 2 tropical cyclones of gale intensity NOTE: The tracking and intensity information for North Indian Ocean Basin tropical cyclones is based primarily upon operational warnings from the Joint Typhoon Warning Center of the U. S. Air Force and Navy (JTWC) at Pearl Harbor, Hawaii. Occasionally some information may be gleaned from the daily Tropical Weather Outlooks and other bulletins issued by the Indian Meteorological Department (IMD), which is the WMO's RSMC for the basin. The MSW are based on a 1-min averaging period, which is used by all U. S. civilian and military weather services for tropical cyclone warnings. For synoptic observations in the North Indian region, both 10-min and 3-min average winds are employed, but IMD makes no attempt to modify the Dvorak scale for estimating tropical cyclone intensity; hence, a 1-min avg MSW is implied. In the North Indian basin JTWC usually does not initiate warnings until a system is well-organized and likely to attain tropical storm status within 48 hours. Tropical Cyclone (TC-01B) 15 - 18 October -------------------------- On 12 October an area of convection developed in the east-central Bay of Bengal roughly 500 nm south-southeast of Calcutta. Synoptic data and microwave imagery indicated a possible LLCC associated with the convection. By the 14th the disturbance had moved farther to the west and lay over the central Bay. Satellite imagery revealed a fully- exposed LLCC with persistent deep convection about 75 nm west-northwest of the center. The MSW was estimated at 25 kts--a tropical depression by NWP basin warning criteria. The Indian Meteorological Department (IMD) did classify the developing system as a depression at 0600 UTC on 15 October when it was centered approximately 350 nm east-southeast of Visakhapatnam, India. Also, at 15/0600 UTC JTWC issued a Formation Alert for the disturbance. A 15/0117 UTC TRMM pass depicted improved curvature and developing convective bands northwest of the LLCC. Water vapor imagery also revealed good outflow over the system. By 1800 UTC IMD had increased the intensity estimate to 30 kts--a deep depression by their terminology. The depression had continued to move westward and the center was located approximately 225 nm southeast of the city of Visakhapatnam. JTWC issued the first warning on TC-01B at 0000 UTC on 16 October. The initial MSW was 35 kts and the center was located about 320 nm east-southeast of Vijayavada, India, moving westward at 8 kts. The current satellite intensity estimate was 30 kts, but QuikScat data indicated that winds of 35 kts were occurring, primarily in the north- western quadrant. The center was partially-exposed with the deep convection situated to the west of the vortex. The cyclone was in an environment of light to moderate vertical shear. The system's forward progress had slowed to 3 kts by 1200 UTC and the center was fully-exposed with the deep convection sheared about 50 nm west of the LLCC. The minimal tropical storm continued to move slowly in a general westerly direction toward southeastern India on 17 and 18 October but never made landfall. JTWC temporarily downgraded the system to a 30-kt depression at 17/1200 UTC but IMD continued to refer to it as a cyclonic storm in their bulletins. Satellite imagery revealed a fully-exposed circulation with convection sheared 85 nm to the west of the LLCC. By 18/0000 UTC, though, satellite intensity estimates had jumped a little as the center had moved near the edge of the convection, so JTWC re-upgraded TC-01B to a minimal tropical storm located about 160 nm east-southeast of Masulipatnam, India. However, twelve hours later the convection had weakened and moved well to the west of the LLCC, which had become difficult to locate. JTWC down- graded the cyclone once more to a depression and issued their last warning, placing the center with 25-kt winds about 115 nm east- southeast of Masulipatnam. (IMD, however, was still carrying the system as a cyclonic storm at 1800 UTC but had downgraded it to a low-pressure area by the following day.) There were no reported human fatalities in India from this weak tropical cyclone, but a press report indicated that gale-force winds in the Srikakulam district killed at least 100 pelican chicks by blowing them out of their nests. Tropical Cyclone (TC-02B) 26 - 28 October -------------------------- The second North Indian Ocean tropical cyclone of the month (and also of the year) had its roots in an area of convection which developed about 200 nm west-northwest of the Andaman Islands late on 24 October. Synoptic data indicated the presence of a weak cyclonic circulation with good outflow aloft. JTWC upgraded the development potential of the disturbance to Fair at 1800 UTC on the 25th. IMD classified the system as a depression with 25-kt winds at 0600 UTC on 26 October when it was located about 500 nm south-southeast of Calcutta. By 1800 UTC the disturbance had moved farther west into the central Bay of Bengal. Convection was intense at times but did not sustain itself. JTWC estimated the winds at 20-30 kts and issued a Formation Alert. By 1200 UTC on 27 October the depression had moved northward toward the head of the Bay. Since the system was moving into a region of increased shear, and also since the majority of the associated deep convection lay over land, JTWC cancelled the Formation Alert at 1500 UTC. A 27/1454 UTC SSM/I pass indicated a convective band east of the system wrapping into the LLCC. The STWO issued by JTWC at 1800 UTC estimated the MSW at 25-30 kts (a tropical depression by NWP warning criteria) and downgraded the development potential to Fair. However, shortly thereafter the first warning was issued on TC-02B based upon satellite intensity estimates of 35 and 55 kts. Animated satellite imagery depicted increased organization with the convective band noted above wrapping into the LLCC. Convection was also re-developing over the center and increasing in areal extent. The cyclone was centered about 125 nm south-southwest of Calcutta and moving northward at 6 kts. The MSW was estimated at 35 kts. IMD also upgraded the system to a cyclonic storm, thereby implying winds of at least gale force. The center of TC-02B crossed the northeastern coast of India about 85 km southeast of Calcutta at approximately 27/2300 UTC. By 0600 UTC on the 28th the storm was a weakening depression centered about 65 km southwest of Dhaka, Bangladesh, tracking northeastward at 15 kts. Strong upper-level southwesterlies had pushed the convection to the northern Bangladesh border. There were media reports of casualties associated with this tropical cyclone in Bangladesh. At least 30 persons were reported dead and 200 fishermen were missing. Winds reportedly reached 55 kts (likely in gusts, although this is not certain) and caused damage to homes, crops, trees and electrical lines. *********************************************************************** SOUTHWEST INDIAN OCEAN (SWI) - South Indian Ocean West of Longitude 90E Activity for October: No tropical cyclones *********************************************************************** NORTHWEST AUSTRALIA/SOUTHEAST INDIAN OCEAN (AUW) - From 90E to 135E Activity for October: No tropical cyclones *********************************************************************** NORTHEAST AUSTRALIA/CORAL SEA (AUE) - From 135E to 160E Activity for October: 1 non-tropical (possibly hybrid) LOW Northeast Australia/Coral Sea Tropical Activity for October ----------------------------------------------------------- A small LOW developed just south of Mackay on the tropical east coast of Queensland around 0000 UTC on 30 October. The system formed east of a mid- to upper-level trough which was pivoting from a north- west/southeast tilt to a southwest/northeast tilt over eastern Australia. Strong warm-air advection was occurring through deep layers between Rockhampton and Brisbane east of this trough on the 30th and heavy rain began falling over the region. The LOW rapidly intensified and produced gale- to storm-force winds along and off the south Queensland coast during 31 October as a tight pressure gradient developed between the LOW and a HIGH over the Tasman Sea to the south. The LOW developed over SSTs between 23 and 24 degrees Celsius. On the 31st the LOW began to move southeastward away from Australia and had moved across 160E into the Wellington AOR by 0600 UTC on the 1st of November. (This LOW was not a tropical cyclone, but appeared to have some hybrid or subtropical features.) Many locations between Brisbane and Mackay registered rainfall totals in excess of 100 mm for the 24 hours ending at 30/2300 UTC with a couple of stations reporting more than 200 mm. However, a long- running drought had preceded this event and the run-off from the heavy rains was not excessive enough to produce any significant stream flooding. Several coastal stations reported sustained winds to gale force with gusts exceeding 50 kts, including Rundle Island AWS (41 kts gusting to 51 kts between 30/1232 and 1250 UTC), Lady Elliot Island (37 kts gusting to 50 kts between 30/0722 and 0845 UTC), and Double Island Point AWS (43 kts gusting to 50 kts around 31/0338 UTC). The highest winds were experienced at the Cape Moreton AWS where the maximum 10-min avg wind reported was 45 kts and the peak gust was 55 kts. This station reported gales from 0200 UTC on the 30th through 1202 UTC on the 31st. The wind brought down trees and power lines with power blackouts in Brisbane suburbs and on the Sunshine Coast just north of Brisbane. The wind and rain led to some traffic accidents, one causing two deaths and another resulting in a serious injury. On the Sunshine and Gold Coasts marine craft broke their moorings and were set adrift. There was also serious beach erosion noted at Maroochydore and Noosa on the Sunshine Coast. (The information presented above was sent to me by Jeff Callaghan of the Brisbane TCWC. A special thanks to Jeff for sending me the report.) *********************************************************************** SOUTH PACIFIC (SPA) - South Pacific Ocean East of Longitude 160E Activity for October: No tropical cyclones *********************************************************************** EXTRA FEATURE In order to shorten the amount of typing in preparing the narrative material, I have been in the habit of freely using abbreviations and acronyms. I have tried to define most of these with the first usage in a given summary, but I may have missed one now and then. Most of these are probably understood by a majority of readers but perhaps a few aren't clear to some. To remedy this I developed a Glossary of Abbreviations and Acronyms which I first included in the July, 1998 summary. I don't normally include the Glossary in most months in order to help keep them from being too long. If anyone would like to receive a copy of the Glossary, please e-mail me and I'll be happy to send them a copy. *********************************************************************** AUTHOR'S NOTE: This summary should be considered a very preliminary overview of the tropical cyclones that occur in each month. The cyclone tracks (provided separately) will generally be based upon operational warnings issued by the various tropical cyclone warning centers. The information contained therein may differ somewhat from the tracking and intensity information obtained from a "best-track" file which is based on a detailed post-seasonal analysis of all available data. Information on where to find official "best-track" files from the various warning centers will be passed along from time to time. The track files are not being sent via e-mail. They can be retrieved in the following manner: (a) FTP to: hrd-type42.nhc.noaa.gov [140.90.176.206] (b) Login as: anonymous (c) For a password use your e-mail address (d) Go to "data" subdirectory (Type: cd data) (e) Set file type to ASCII (Type: ascii) (f) Transfer file (Type: get remote_file_name local_file_name ) (The files will be named with an obvious nomenclature--using October as an example: oct00.tracks) (g) To exit FTP, type: quit Both the summaries and the track files are standard text files created in DOS editor. Download to disk and use a viewer such as Notepad or DOS editor to view the files. The first summary in this series covered the month of October, 1997. If anyone wishes to retrieve any of the previous summaries, they may be downloaded from the aforementioned FTP site at HRD. The summary files are catalogued with the nomenclature: oct00.sum, for example. Back issues can also be obtained from the following websites (courtesy of Michael Bath, Michael V. Padua, Tom Berg, Michael Pitt, and Rich Henning): OR Another website where much information about tropical cyclones may be found is the website for the UK Meteorological Office. Their site contains a lot of statistical information about tropical cyclones globally on a monthly basis. The URL is: TROPICAL CYCLONE REPORTS AVAILABLE I have discovered that JTWC now has available on its website the complete Annual Tropical Cyclone Report (ATCR) for 1999 (1998-1999 season for the Southern Hemisphere). Also, ATCRs for earlier years are available also. The URL is: Also, TPC/NHC has available on its webpage nice "technicolor" tracking charts for the 1999 Atlantic and Eastern North Pacific tropical cyclones; also, preliminary storm reports for all the 1999 Atlantic and Eastern North Pacific cyclones are now available. In addition storm reports are now available for the Atlantic and Eastern Pacific tropical cyclones in 2000. The URL is: Prepared by: Gary Padgett E-mail: garyp@alaweb.com Phone: 334-222-5327 (nights & weekends) / 850-882-2594 (weekdays) *********************************************************************** *********************************************************************** 02.15.01 / Typhoon2000.com