GARY PADGETT'S MONTHLY GLOBAL TROPICAL CYCLONE SUMMARY MAY, 2003 (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.) ************************************************************************* MAY HIGHLIGHTS --> Damaging cyclone strikes eastern Madagascar --> Bay of Bengal cyclone strikes Myanmar --> Northwest Pacific active--tropical storm causes fatalities in Philippines --> First tropical storm of season in Northeast Pacific basin forms ************************************************************************* ***** Feature of the Month for May ***** UPDATED NORTHEAST PACIFIC STATISTICS For the past two years I have featured tables of Atlantic and Northeastern Pacific monthly net tropical activity (NTC). For this month's feature I have included tables for the Northeast Pacific basin--the Atlantic was featured in the March monthly summary. When breaking up a tropical cyclone season temporally (into months), some decisions have to be made regarding intermonthly cyclones. I have previously explained in detail my reasoning here, and interested persons can find this in the March, 2002, summary, which can be obtained from any of the websites listed at the end of this summary. Tropical cyclonic activity in the Northeast Pacific (NEP) during 2002 extended from late May into early November. The first table below lists the monthly statistics for the months May through November, inclusive, as well as the seasonal totals. The statistics cover the entire NEP basin from the west coast of Mexico to the International Dateline. The NSD, HD and IHD parameters do not include any days which a system may have spent in the Northwest Pacific basin west of longitude 180. The 2002 season in the NEP basin was about average--the NTC was 97. NOTE: The parameters NS, H, IH, NSD, HD, IHD and NTC are those which are used by the Colorado State University forecast team headed by Dr. Bill Gray. Documentation for these can found on the CSU website: Northeast Pacific Tropical Cyclone Season of 2002 ------------------------------------------------- Month NS H IH NSD HD IHD NTC MAY 1 1 1 5.50 2.75 0.50 10.09 JUN 1 0 0 2.00 0.00 0.00 1.47 JUL 3 2 1 14.75 6.25 2.25 21.09 AUG 5 3 3 16.00 6.75 2.50 33.29 SEP 2 0 0 10.75 3.50 2.00 10.02 OCT 3 2 1 13.25 4.25 1.75 18.78 NOV 0 0 0 2.50 2.50 0.00 1.86 TOTAL 15 8 6 64.75 26.00 9.00 96.60 The next table gives NEP statistics for the period 1971-2002, arranged by months. The year 1971 was chosen as a starting point since, even though the Dvorak method of satellite analysis had not yet been introduced, there was extensive aerial reconnaissance of NEP storms that season and during the following two. Reconnaissance flights into NEP cyclones were curtailed after 1973, but by 1974 the initial Dvorak method was being used and tropical cyclone intensities in the Best Track file can be considered somewhat reliable. Northeast Pacific Basin Monthly NTC Table Based on Period 1971-2002 ----------------------------------------- Month NS H IH NSD HD IHD NTC JAN 1 1 0 3.25 2.00 0.00 0.14 FEB 0 0 1 3.00 2.25 0.50 0.20 MAR 1 0 0 1.00 0.00 0.00 0.04 APR 0 0 0 0.00 0.00 0.00 0.00 MAY 16 9 2 55.25 16.75 2.75 2.06 JUN 68 36 14 251.25 93.25 26.00 10.59 JUL 120 65 36 526.25 234.75 74.25 23.45 AUG 127 77 37 659.25 265.50 60.50 25.08 SEP 113 69 35 548.50 263.25 79.00 24.23 OCT 64 37 20 301.25 137.00 40.75 13.13 NOV 11 3 0 33.50 8.25 0.00 0.89 DEC 2 1 0 7.50 1.00 0.00 0.19 TOTAL 523 298 145 2390.00 1024.00 283.75 AVG 16.3 9.3 4.5 74.7 32.0 8.9 The following chart tabulates the same set of NEP statistics but arranged by year. The active period which abruptly began in 1982 and continued through 1994, except for a short "coffee break" in the late 1980s, is most striking. Prior to 1982, the only really active year was 1978, and following 1994, the only year with an above-normal NTC was the strong El Nino year of 1997. Northeast Pacific Basin Annual NTC Table Based on Period 1971-2002 ---------------------------------------- Year NS H IH NSD HD IHD NTC 1971 18 12 6 84.00 38.50 6.00 112 1972 14 8 4 83.25 33.75 4.50 88 1973 12 7 3 62.25 28.50 7.25 78 1974 18 11 3 63.75 22.25 2.50 79 1975 17 9 4 71.75 26.75 5.50 88 1976 15 9 5 66.50 27.25 9.75 97 1977 8 4 0 20.50 5.25 .00 22 1978 19 14 7 102.75 51.50 16.00 150 1979 10 6 4 33.75 13.75 3.25 56 1980 14 7 3 48.25 22.75 2.75 65 1981 15 8 1 58.00 18.25 1.00 57 1982 23 12 5 106.50 39.25 7.50 121 1983 21 12 8 110.00 47.75 16.25 152 1984 21 13 7 103.50 46.25 14.75 145 1985 23 13 8 108.50 49.75 8.50 142 1986 17 9 3 62.50 28.75 6.75 86 1987 20 10 4 78.50 29.00 7.75 100 1988 15 7 3 65.25 29.50 6.50 81 1989 17 9 4 67.25 27.25 5.75 88 1990 21 16 6 126.00 58.25 20.25 168 1991 14 10 5 86.25 44.00 14.00 119 1992 27 16 10 148.75 65.50 20.75 199 1993 15 11 9 86.75 50.75 16.75 145 1994 20 10 5 85.50 33.00 17.00 125 1995 10 7 3 51.75 22.25 9.00 73 1996 9 5 2 32.00 13.00 3.25 45 1997 19 9 7 78.50 33.50 15.00 124 1998 13 9 6 62.75 33.00 10.75 102 1999 9 6 2 44.50 23.50 6.00 60 2000 19 6 2 67.50 16.75 4.75 70 2001 15 8 2 58.25 18.50 5.00 69 2002 15 8 6 64.75 26.00 9.00 97 AVG 16.3 9.3 4.5 74.7 32.0 8.9 The final table is identical to the preceding one except that it covers the Eastern North Pacific proper only--from longitude 140W eastward to the Mexican and Central American coasts. The "days" parameters--NSD, HD and IHD--do not include portions of cyclones spent west of 140W. (Note: A similar set of statistics appeared as the monthly feature in the July, 2000, summary. Those had been calculated by John Wallace and covered the period 1971-1999. John had calculated them by hand from the Best Track file, and his methodology was to include only the storms originating east of 140W, but to include in the "days" parameters the entire life cycles of the cyclones. An NTC calculated thusly is also useful in that it reflects the level of activity generated by the Eastern North Pacific systems. However, my rather simple software which reads through the NEP Best Track file isn't set up to do that, and the re-programming necessary to emulate John's procedure would be too time-consuming at the present moment.) Eastern North Pacific (East of 140W) Annual NTC Table Based on Period 1971-2002 ----------------------------------------- Month NS H IH NSD HD IHD NTC 1971 18 12 6 80.75 36.75 6.00 122 1972 12 8 3 62.50 24.75 2.75 77 1973 12 7 3 51.75 24.00 7.00 81 1974 17 11 2 59.25 18.75 2.25 78 1975 16 8 4 68.75 26.00 5.50 94 1976 14 8 5 57.75 22.50 9.75 99 1977 8 4 0 20.50 5.25 .00 24 1978 18 12 6 73.00 35.25 13.25 134 1979 10 6 4 33.75 13.75 3.25 62 1980 14 7 3 43.75 20.00 2.75 69 1981 15 8 1 55.25 18.25 1.00 62 1982 19 11 4 76.75 33.00 6.00 108 1983 21 12 8 98.00 46.25 15.00 162 1984 18 12 6 93.25 43.50 14.50 147 1985 22 11 7 90.25 37.00 5.75 130 1986 17 9 3 56.25 24.75 5.25 88 1987 18 9 4 66.00 24.75 7.75 101 1988 13 6 1 51.25 18.75 2.25 58 1989 17 9 4 62.75 24.75 5.75 94 1990 20 16 6 115.25 55.50 18.00 177 1991 14 10 5 82.00 42.75 14.00 131 1992 24 14 8 132.75 57.00 18.25 192 1993 14 10 8 73.50 42.25 15.25 143 1994 17 8 4 51.50 14.50 4.25 80 1995 10 7 3 51.75 22.25 9.00 82 1996 9 5 2 32.00 13.00 3.25 50 1997 17 9 7 67.25 33.50 15.00 133 1998 13 9 6 60.75 32.75 10.75 113 1999 9 6 2 35.50 16.25 5.75 60 2000 17 6 2 56.50 15.75 4.75 72 2001 15 8 2 58.25 18.50 5.00 76 2002 12 6 5 48.00 19.25 8.50 86 AVG 15.3 8.9 4.2 64.6 27.5 7.7 A couple of adjustments have been made from the original NS values obtained from the Best Track file. In 1975 sixteen tropical storms were named by the Eastern Pacific Hurricane Center in San Francisco-- the agency responsible for issuing warnings in that basin prior to 1988. However, the program reported 17 tropical storms. A hurricane formed in subtropical latitudes in the Central North Pacific in late August. The cyclone remained unnamed at the time, but was later added to the Best Tracks file. The final position in the storm's track, stilled flagged as tropical, was 138W. However, the latitude was 54N! It seems highly unlikely that the system was still exhibiting tropical storm characteristics at latitude 54N in the Eastern Pacific, so I did not include that storm. The other adjustment was made for 1982. The San Francisco center named 19 storms, Aletta through Tara. However, the program reported only eighteen. The first data point for Tropical Storm Emilia, at 0600 UTC on 13 July, was 10.5N, 140.5E, with 35-kt winds. It seems likely that a tropical disturbance suddenly intensified and that the Eastern Pacific Hurricane Center assigned the name Emilia just as it was crossing 140W. There is also the possibility that the center position was readjusted westward during post-storm analysis. So I did count Tropical Storm Emilia as an Eastern North Pacific cyclone, but all its "days" parameters occurred west of 140W. ************************************************************************* ACTIVITY BY BASINS ATLANTIC (ATL) - North Atlantic Ocean, Caribbean Sea, Gulf of Mexico Activity for May: No tropical cyclones Atlantic Tropical Activity for May ---------------------------------- A quiet month of May followed the first April Atlantic tropical cyclone on record. Since 1886 twelve tropical storms have formed during May, with additional tropical depressions and subtropical storms tracked. The last tropical storm to form in May was Tropical Storm Arlene in 1981, which formed in the western Caribbean during the first week of May. Following a May tropical storm in 1887 and a hurricane in 1889, no more May storms were detected until 1932. However, since 1932 the longest gap between May tropical storms has been eleven years (1959 to 1970 and 1970 to 1981). So the Atlantic basin is overdue for a May tropical storm. There was an interesting system off the southeast U. S. coast during the first week of the month which initially seemed to have delusions of developing into a subtropical storm. A meso-scale convective system from the Gulf of Mexico had moved to a position off the North Carolina coast by 2 May where it exhibited some rotation and had generated some convection near the center. (This information from David Roth.) According to Bob Hart, the Cyclone Phase Space had initially indicated possible hybrid or even weak warm-core development, but later runs of the program had backed off a bit and trended toward neutral or cold- core evolution. And Chris Fogarty pointed out that with the upper-level trough open to the northwest of the LOW, it would have been very difficult for a warm-core cyclone to form. ************************************************************************* NORTHEAST PACIFIC (NEP) - North Pacific Ocean East of Longitude 180 Activity for May: 1 tropical storm Northeast Pacific Tropical Activity for May ------------------------------------------- For the fourth consecutive year, the Northeast Pacific basin produced a named tropical cyclone. The only other occasion since 1971 when four consecutive Mays produced a named storm was 1981-1984. In contrast, however, to the rather intense Hurricanes Aletta, Adolph and Alma of the previous three seasons, Tropical Storm Andres of 2003 remained a fairly weak tropical storm. It did have a rather long life span for a weak system, tracking almost to the boundary with the Central North Pacific. The following report on Andres was written by John Wallace of San Antonio, Texas. A special thanks to John for his assistance. TROPICAL STORM ANDRES (TC-01E) 20 - 26 May ----------------------------------------- A. Storm Origins ---------------- The disturbance that became Tropical Storm Andres may have been noted in the ITCZ south of the Bay of Tehuantepec as early as 16 May. However, it is more likely that the system's precursor can be traced to a disturbance that tracked westward from Central America around the 18th. A LOW was definite in satellite imagery later that day, and the LOW slowly strengthened over the next 24 hours until it became organized sufficiently to warrant its upgrade to Tropical Depression One-E at 0300 UTC on 20 May when it was located roughly 475 nm south-southwest of Acapulco, Mexico. The depression tracked westward under the influence of a well-defined subtropical ridge to its north. Conditions remained favorable on the whole for intensification, and the cyclone duly strengthened to Tropical Storm Andres at 1500 UTC on the 20th while positioned roughly 550 nm southwest of Acapulco (this was just 12 hours after the first warning). B. Storm History ---------------- Andres' quick christening was not the shape of things to come. Even at its upgrade its center was difficult to locate, and was later found to be displaced west of the central convection due to westerly shear. The shear was persistent, and Andres failed to thrive in spite of optimistic official forecasts. On the 21st, Andres' unusually swift westward track bent to the west- northwest as the subtropical ridge weakened and moved east. The synoptic environment became slightly more favorable, and Andres reached its peak estimated MSW of 40 kts, with a CP of 1002 mb, at 0900 UTC on 22 May when located some 1025 nm west-southwest of Acapulco. At the time this intensity estimate was considered conservative. Shear prevented the storm from strengthening further, however, and Andres fluctuated around minimal tropical storm strength for the next two days as it raced west- northwest--indeed, its rapid motion was probably the cause of much of the net westerly shear. Though it weakened after its peak, the MSW reached 40 kts twice more, at 0900 UTC on the 23rd and at 2100 UTC on the 24th, as its convection waxed and waned with the vagaries of its environment. Andres' last peak coincided with its crossing of the 26 C isotherm and entry into a more hostile upper-level environment due to a strong trough east of the Hawaiian islands. It quickly weakened to a depression on the 25th as its convection collapsed, while its former arrow-straight, west-northwesterly track bent back to the west with the low-level trade winds. The final advisory on Tropical Depression Andres was issued at 0300 UTC on 26 May with the weakening center located roughly 925 nm east of Hilo, Hawaii, just shy of the CPHC's AOR. The cyclone's remnants dissolved rapidly; there was no significant trace of cyclonic organization by late that day, though its amorphous cloud mass remnant lingered for a few days thereafter. C. Damage and Casualties ------------------------ There are no known casualties or damages associated with Tropical Storm Andres. (Report written by John Wallace) ************************************************************************* NORTHWEST PACIFIC (NWP) - North Pacific Ocean West of Longitude 180 Activity for May: 3 tropical storms ** 1 typhoon ** - one of these considered a tropical storm by JTWC only Northwest Pacific Tropical Activity for May ------------------------------------------- The Northwest Pacific basin experienced a rather active month of May. Three tropical storms were named by JMA, and an additional system was briefly upgraded to tropical storm status by JTWC (and was assigned a name by PAGASA). The only typhoon of the month was Chan-hom, which formed deep in the tropics in the Chuuk area and moved northward out of the tropics, passing well to the east of Guam and the Marianas. Chan-hom became a rather intense storm with the peak MSW reaching 115 kts (per JTWC's analysis). Tropical Storms Linfa and Nangka were rather similar. Each formed in the northeastern South China Sea and followed generally northeasterly tracks. Linfa/Chedeng moved eastward across northern Luzon, where its rains were responsible for significant flooding and loss of life, whereas Nangka/Dodong tracked northeastward, passing between Luzon and Taiwan. The other system, Tropical Storm 03W (named Batibot by PAGASA) followed an erratic course northward off to the east of the southern Philippines. The summaries on Tropical Storms 03W, Linfa, and Nangka were written by Kevin Boyle of Stoke-on-Trent, UK. A special thanks to Kevin for his assistance. Also, a big thanks to Huang Chunliang and Karl Hoarau for sending along synoptic observations relating to Tropical Storm Linfa. CORRECTIONS and ADDENDA to APRIL SUMMARY ---------------------------------------- Huang Chunliang pointed out a few errors that I had made in reporting the observations from Typhoon Kujira: (1) The original summary reported that Aburatsu, Miyazaki Prefecture, had recored SSW winds of 32 kts at 24/1700 UTC. The correct time should read 25/0700 UTC. (2) The station names "Lan Yu" and "Green Island" are better rendered as "Lanyu" and "Ludao". (3) Regarding a 24-hr rainfall total of 342 mm recorded at Tarama on Okinawa on 24 April, I had indicated that I was not sure of the applicable time period. This amount was measured between 0000 and 2400 local time (UTC + 9 hrs) on 24 April. Karl Hoarau pointed out that the pressure readings from Lanyu which I had identified as SLP--the minimum being 965 mb--were almost certainly unadjusted station pressure readings. The station is at an altitude of 325 m, and the center of Kujira passed about 55 nm east of the island per both JMA's and JTWC's warnings. Karl indicated that he had rechecked infrared and microwave images of the storm and found that the system's appearance in satellite imagery was nowhere near a Dvorak T4.5, equivalent to 965 mb. Finally, Huang Chunliang sent along some rainfall observations from Taiwan which had been unavailable earlier when he'd sent the original report. These are as follows: Station Storm Total (20/1600 - 23/1800 UTC) ---------------------------------------------------------------- Shin-liao, Ilan County 155 mm Shuang-Lian Pi, Ilan County 143 mm Tai-on, Hualien County 119 mm Ilan 90 mm Daping, Taipei County 85 mm Lanyu 68 mm Ludao 64 mm Keelung 58 mm A thanks to Chunliang and Karl for sending these corrections and addenda. I will update the April summary and send a corrected version to the archive sites. TROPICAL STORM (TC-03W / BATIBOT) 17 - 20 May -------------------------------------- Batibot: PAGASA name, is the name of a Filipino children's television show similar to Sesame Street A. Storm Origins ---------------- The origins of Tropical Storm 03W can be traced back to an area of deep convection, noted in a STWO issued at 1730 UTC, 16 May, located near 5.6N, 132.2E (approximately 180 nm southwest of Palau). Upper- level analysis revealed good diffluence aloft and a favourable wind shear environment while animated infrared imagery indicated the existence of a possible LLCC. The development potential was described as poor, but was raised to fair at 17/0600 UTC when animated multi- spectral satellite imagery revealed cycling but disorganized deep convection over possible multiple LLCCs embedded within a surface trough. JMA began issuing warnings at this time, classifying the system as a 30-kt (10-min avg) tropical depression near 7.1N, 130.5E. The first JTWC warning at 17/1800 UTC superceded the TCFA issued at 17/1130 UTC. B. Storm History ---------------- At the time of the first warning, TD-03W was located approximately 80 nm east of Mindanao, Philippines (7.3N, 127.9E.) Initial movement was toward the west at 5 kts with the MSW set at 25 kts. Animated infrared satellite and microwave imagery indicated that the LLCC was continuing to slowly organize with radial deep convection turning toward the centre of the system. Despite unfavourable wind shear conditions the MSW was raised slightly to 30 kts at 18/0600 UTC. At this time, the broad LLCC was moving slowly northward at 2 kts, and based on QuikScat, SSM/I and synoptic data, was relocated to a position approximately 210 nm east of Mindanao, Philippines (7.7N, 129.9E). (JMA also repositioned the centre to near 8.6N, 130.3E.) At this point, deep convection had been decreasing and TD-03W was suffering from the effects of the wind shear as evidenced by the partial exposure of the LLCC east of the deep convection. However, deep convection began to pick up again, and at 19/0000 UTC JTWC upgraded the system to a 35-kt tropical storm. The still partially-exposed LLCC was then located approximately 270 nm east of Mindanao, (9.1N, 130.8E), moving in a northeastward direction at 7 kts. PAGASA initiated warnings at 19/0600 UTC and assigned their internal name Batibot. (Note: No international name was given to this system as JMA did not regard it as a tropical storm. Neither did any other agency, including the CWB of Taiwan who had been monitoring the system through their bulletins since 18/1200 UTC but never forecast tropical storm intensity. HKO ranked TS-03W as a tropical depression but did not issue statements. No warnings were issued by NMCC.) A significant decrease in deep convection was noted at 19/1200 UTC. and the LLCC became difficult to locate in infrared satellite images. Subsequently, TS-03W was downgraded to tropical depression status. The position was estimated to be approximately 325 nm west of Yap (10.3N, 132.7E). Based on infrared satellite imagery and a 19/1812 UTC TRMM pass, another relocation was required at 1800 UTC. (The LLCC's position was relocated further northwest to 10.7N, 131.1E.) Forward motion had become northwestward at 6 kts toward a weakness caused by a passing shortwave trough. The perspective from the multi- spectral satellite imagery at 19/2330 UTC was that of a fully-exposed centre with most of the sheared deep convection concentrated east and south of the LLCC. A little over six hours later, the situation had not improved and JTWC issued the final warning at 20/0600 UTC. The final fix of the very poorly-defined LLCC was approximately 355 nm east- northeast of Tacloban, Philippines (12.8N, 130.8E.) PAGASA and JMA ceased writing bulletins at 20/1200 UTC while CWBT continued to issue advisories until 22/0000 UTC. C. Damage and Casualties ------------------------ No reports of damage or casualties associated with Tropical Storm 03W/Batibot have been received. (Report written by Kevin Boyle) TYPHOON CHAN-HOM (TC-04W / TY 0303) 18 - 28 May -------------------------------------- Chan-hom: contributed by Laos, is a kind of tree A. Storm Origins ---------------- JTWC issued a TCFA at 1500 UTC on 18 May for a disturbance located approximately 300 nm southwest of Chuuk. (The disturbance was not mentioned in the daily STWO on 15 May, so must have begun to develop on either the 16th or 17th--I am missing the STWOs for those dates.) Deep convection was cyclic, but organization had improved during the previous six hours. The convection was near the broad LLCC, and a 200-mb analysis indicated moderate vertical shear and good diffluence aloft. Also, a westerly wind burst was enhancing winds to the south of the system. The first JTWC warning on TD-04W was issued at 19/0000 UTC and placed the center roughly 470 nm southeast of Guam, moving north at 5 kts. Visible and microwave imagery indicated improving organization of the LLCC. (JMA had classified the system as a tropical depression earlier at 1200 UTC on the 18th.) B. Storm History ---------------- A U. S. Air Force Reserves' reconnaissance plane investigating the depression found a pressure of 1003 mb and maximum FLW of 42 kts in the southeast quadrant at 19/0508 UTC, and 50 kts in the southern quadrant at 0603 UTC. JTWC upgraded TD-04W to tropical storm status in the second warning, issued around 0900 UTC. At 0600 UTC the center was located approximately 140 nm west-southwest of Chuuk, moving northeast- ward at 4 kts. TS-04W remained at 35 kts for the remainder of the 19th as it trekked slowly north and northeastward a little over 100 nm west of Chuuk. A weakness was seen developing in the low to mid-level ridge to the north, enhanced by a mid-latitude trough translating eastward from the Asian continent. The tropical cyclone was forecast to continue its general northward motion toward this weakness developing in the ridge. By 1200 UTC on 20 May the tropical storm had reached a position about 80 nm west-northwest of Chuuk. Satellite CI estimates ranged from 35 to 55 kts, and a 20/1118 UTC SSM/I pass indicated that the system had become more concentric with good radial outflow and spiral banding features while remaining under a very favorable upper-level environment. JTWC upped the MSW to 55 kts at 1200 UTC, and JMA upgraded the cyclone to tropical storm status, assigning the name Chan-hom. (NMCC and CWBT also upgraded the system to tropical storm status at 20/1200 UTC.) A reconnaissance aircraft had made several fixes during the early hours of the 20th, finding a maximum FLW of 67 kts in the southern quadrant at 20/0326 UTC with a CP of 996 mb. On the 21st Tropical Storm Chan-hom continued to track slowly northward along the western periphery of a mid-level ridge situated to the northeast, moving toward the afore- mentioned weakness in the subtropical ridge. The storm slowly gained in intensity as the day wore on--by 1800 UTC JTWC and NMCC were reporting 60 kts (1-min and 10-min averages, respectively) while JMA and CWBT were estimating 55 kts (10-min avg). At 22/0000 UTC Chan-hom was located about 380 nm east-southeast of Guam, trudging northward at 7 kts. A 21/2204 UTC SSM/I pass indicated the development of a banding eye feature, and CI estimates had reached 55 and 65 kts. Based on this, JTWC upgraded Chan-hom to a 65-kt typhoon at 0000 UTC, but the intensity remained pegged at minimal typhoon intensity for another 24 hours. (NMCC and CWBT upgraded Chan-hom to typhoon status at 23/0000 UTC, and JMA did so at 23/0600 UTC.) U. S. Air Force Reserves' reconnaissance flights into Chan-hom during the early hours of the 22nd found a peak FLW of 67 kts in the eastern quadrant at 22/0330 UTC, and the pressure had dropped to 983 mb by 0538 UTC. By 23/0000 UTC the typhoon had reached a position 380 nm north- northeast of Guam, and JTWC upped the MSW to 85 kts based on CI estimates ranging from 65 to 102 kts. Chan-hom at this time was sporting a 20-nm diameter eye. The storm increased steadily in intensity and by 1800 UTC had reached its peak intensity of 115 kts, based on CI estimates of 115 and 127 kts. (The peak 10-min avg MSW values for Chan-hom from JMA, NMCC and CWBT were 85, 75 and 85 kts, respectively.) Gales reached out around 100 nm from the 10-nm symmetrical eye, and the radius of 50-kt winds was 40 nm. JMA estimated the minimum CP at 940 mb. Typhoon Chan-hom was located approximately 450 nm east-northeast of Guam at this time, and had turned to a north-northeastward heading at 10 kts. Chan-hom maintained its peak intensity through 25/0600 UTC (per JTWC's warnings) as CI numbers remained at 115 kts. However, as early as 0000 UTC on the 24th animated water vapor imagery showed some dry air entrainment into the southeastern quadrant, and the eye had become irregular and ragged in appearance by 24/1200 UTC. The storm was then located approximately 800 nm west of Wake Island, and satellite imagery suggested that the poleward outflow was being temporarily enhanced by an approaching deep mid-latitude trough. Chan-hom's forward motion began to accelerate to the northeast as it became increasingly influenced by the westerlies. At 24/1800 UTC it was moving northeastward at 17 kts. JTWC reduced the intensity to 90 kts at 25/0600 UTC with Chan-hom then located about 660 nm west-northwest of Wake Island. The dry air entrainment had continued, vertical shear was increasing, and the system was starting to link up with the mid-latitude trough. Extratropical transition was underway, and at 25/1800 UTC JTWC lowered Chan-hom's MSW to minimal typhoon intensity of 65 kts. By 26/0000 UTC the storm had lost much of its convection, and at 0600 UTC all the warning agencies downgraded Chan-hom to tropical storm status (except NMCC, which main- tained the system as a typhoon for six more hours). Chan-hom was then located over 1100 nm west of Midway Island, scooting northeastward at 22 kts. Even though the system was becoming extratropical, some tropical features lingered. At 1200 UTC the JTWC warning remarked that Chan-hom remained vertically stacked with some tropical banding features still evident. By 1800 UTC the storm was located about 950 nm west-northwest of Midway Island, and the LLCC had become decoupled from the remaining deep convection. JTWC declared Chan-hom extratropical at 27/0000 UTC when located about 850 nm west-northwest of Midway, still moving north- eastward at 22 kts, and JMA classified the former typhoon as an extra- tropical system six hours later. The remnants of Chan-hom continued to weaken and move eastward, crossing the International Dateline shortly before 28/1200 UTC. The final reference to the system in JMA's High Seas Bulletins, at 28/1800 UTC, placed a weak 25-kt LOW several hundred miles north of Midway Island. Early in its history Chan-hom posed a potential threat to the island of Guam. Fortunately, this failed to materialize, sparing the island from what could have been the third typhoon strike in less than a year. Chan-hom did, however, have an effect on the island. After the typhoon had passed by Guam well to the east, the resulting wind shift began to redirect a plume of ash from the continuing eruption of a volcano on Anatahan, an uninhabited island 70 nm north of Saipan, toward Guam. Guam's Environmental Protection Agency issued a volcanic haze advisory for the island, urging residents, especially those with respiratory problems, to take precautions. In addition to the ash, sulfur dioxide and other volcanic gases reacted with oxygen and atmospheric moisture to produce volcanic smog, or vog, and acid rain. The vog can aggravate pre-existing respiratory ailments, and the acid rain damages crops. C. Damage and Casualties ------------------------ No damage or casualties are known to have resulted from Typhoon Chan-hom. (Report written by Gary Padgett) TROPICAL STORM LINFA (TC-05W / STS 0304 / CHEDENG) 25 - 31 May ------------------------------------------------- Linfa: contributed by Macau, is the Macanese name for the lotus, an Oriental water lily with pinkish flowers and large leaves Chedeng: PAGASA name, is a Filipino nickname for either males or females; it is also a term used for the German car Mercedes Benz A. Storm Origins ---------------- An area of convection developed and persisted near 14.1N, 114.9E, or approximately 350 nm west of Manila, Philippines. This was included in JTWC's STWO issued at 1900 UTC on 23 May. Animated enhanced infrared satellite imagery revealed that the convection was associated with a developing LLCC located in the southeastern quadrant of an anticyclone anchored over the Gulf of Tonkin with divergence aloft, as evidenced by a 200-mb analysis. Development potential for the next 24 hours was poor. A day later, at 24/1900 UTC, the potential was upgraded to good and a TCFA issued. QuikScat data at this time revealed that the LLCC had consolidated (with deep cycling convection) and was being fueled by a westerly wind burst. Vertical wind shear in the area was weak, an ideal condition necessary for further development. JTWC kicked off Tropical Storm Linfa's career with the first warning, issued at 0000 UTC on 25 May. JMA started issuing bulletins six hours later. At the same time PAGASA also began writing warnings on Chedeng, that agency's third named system of the year. (At 25/0600 UTC PAGASA upgraded Chedeng to a tropical storm.) The depression was moving very slowly northwestward away from the Philippines at 3 kts at this time, and during the 25th Chedeng traced a slow, labourious cyclonic loop. The expectations were that once TD-05W had intensified beyond its weak, shallow stage, it would move slowly eastward towards Luzon along the northern periphery of the low to mid-level near-equatorial ridge axis located to the south. The slow erratic motion allowed for some strengthening, and JTWC upgraded the depression to a 45-kt tropical storm on Warning #4, issued at 25/1800 UTC. TS-04W was named Linfa six hours later when JMA also upgraded the system to tropical storm status. B. Storm History ---------------- At 26/0000 UTC Tropical Storm Linfa was still almost stationary near 16.1N, 118.2E, or approximately 185 nm northwest of Manila. (Note: All Asian agencies were warning on Linfa by this time as a tropical storm with the introduction of CWBT and HKO, which had begun issuing advisories at 25/0600 UTC and 25/1200 UTC, respectively. NMCC began releasing statements at 26/0300 UTC, classifying Linfa as a 40-kt tropical storm (10-min avg) three hours later.) This very slow motion gave the opportunity for the tropical cyclone to slowly develop and intensify a little more, and by 26/1800 UTC the MSW was up to 55 kts. At this time Linfa began moving toward the east to begin its attack on the Philippines. At this juncture, Linfa failed to intensify further, and at 0000 UTC, 27 May, was making landfall on Luzon as a 55-kt tropical storm. Moving eastward at 7 kts, Tropical Storm Linfa crossed the northern Philippine island of Luzon (weakening to 35 kts in the process) and had re-emerged back over water by 27/1800 UTC. At 28/0000 UTC Linfa was downgraded to a 25-kt depression. (JMA had dropped the system to a 35-kt tropical storm, but at 28/0000 UTC upped the intensity slightly to 40 kts (10-min avg). The remaining Asian TCWCs also retained tropical storm status.) The JTWC warning (#13) issued at this time noted that the main centre was weakening and that a new LLCC was developing near 18.6N, 123.6E, based upon careful analysis of a 27/2139 UTC QuikScat pass. This was forecast to become the dominant centre within 12 hours. All the Asian TCWCs began following this new LLCC as of 28/0000 UTC while JTWC continued to track the old centre through 28/1800 UTC. This is the primary reason for the large deltas in centre position and intensity on the 28th and JTWC's downgrade to tropical depression status. The mid- level portion of the original circulation had coupled up with the new LLCC by 28/1200 UTC. HKO issued their final warning on Linfa, still as a 35-kt tropical storm, at 28/1500 UTC. The agency did upgrade the system back to severe tropical storm status after it had exited their area of warning responsibility. After the amalgamation of both LLCCs, JTWC relocated the position of the new LLCC at 29/0000 UTC, resulting in a jump to 22.3N, 125.8E, or approximately 250 nm south-southwest of Naha, Okinawa. Linfa was at this time moving on a north-northeasterly heading at 11 kts. A 28/2331 UTC SSM/I pass showed that Linfa was becoming more organized with distinct banding features and increased convection consolidating around the LLCC. By 29/0600 UTC the MSW had increased to 35 kts and Linfa was once again upgraded to a tropical storm. This was based on banding features observed in recent SSM/I and animated multi-spectral imagery. However, the system was seen to be asymmetrical, partially-exposed, and with almost all the deep convection confined to the eastern semicircle. The system then accelerated northeastward at a faster pace of 16 kts which took it out of PAGASA's AOR by 29/1800 UTC. Accordingly, PAGASA ceased writing bulletins. The strengthening Linfa passed 140 nm south- east of Naha, Okinawa around this time. Twelve hours later, Linfa reached a secondary peak of 60 kts (based on WC-130 reconnaissance data), although recent animated multi-spectral satellite imagery indicated that the LLCC remained partially-exposed. Turning to a more northerly heading at 23 kts, Linfa began to slowly weaken, and by the time JTWC issued their final warning at 30/1200 UTC, the MSW had fallen to 50 kts. At this time animated enhanced infrared and water vapor satellite imagery, and a 30/1751 UTC TRMM pass, revealed that the system had completed extratropical transition. The final warning placed the centre of Linfa approximately 120 nm south of Iwakuni, Japan, or near 32.0N, 132.0E. NMCC and CWBT both ended their warning coverage at 31/0000 UTC while JMA monitored the extratropical system for a further 12 hours. Continuing northward, the centre of the extratropical Linfa made landfall near Uwajima City, Japan, around 0500 local time on May 31. The final position of the storm plotted by JMA was near 36.0N, 135.0E, with the centre just about to enter the Sea of Japan. C. Meteorological Observations ------------------------------ 1. Philippines -------------- Karl Hoarau passed along the following surface observations in association with Linfa. (A thanks to Karl for sending the information.) The coastal station of Botolan (WMO 98324) recorded 153 mm during the 24-hour period from 26/0000 UTC to 27/0000 UTC. The station also reported 68 mm between 0000 and 0600 UTC on the 27th. Karl also passed on some more rainfall data listed below: Period from 26th 0000 UTC to 28th 0000 UTC Location WMO Code Rainfall (mm) ------------------------------------------- Cabanatuan 98330 225 Subic Bay 98426 239 Sangley Point 98428 239 Iba 98324 289 Baguio 98328 364 Dagupan* 98325 723 *At this station, 378 mm were recorded on the 27th from 0600 to 1200 UTC, and 251 mm on 27th from 1200 to 1800 UTC. This means that 629 mm were recorded in 12hrs! Tropical Storm Linfa passed 50 nm west-northwest of the station WMO 47945 (25.8N, 131.2E) around 0100 UTC-0200 UTC on 29 May. The station reported a south wind of 32 kts (10-min avg) and a minimum SLP of 991.2 mb at 0300 UTC, 30th May. From 1200 UTC on the 29th to 0000 UTC on the 30th 73 mm of rainfall was reported. Dagupan (WMO 98325), near the west coast of Luzon, reported a minimum SLP of 989.0 mb at 27/0200 UTC, but a wind speed of only 10 kts was recorded. This station is protected somewhat by the mountains to the east which act as a barrier to winds from the northeast through the southeast. 2. Japan -------- Huang Chunliang has sent an extensive amount of information from several Japanese stations. (A thanks to Chunliang for sending along the observations.) a. Rainfall observations ------------------------ JMA station reports exceeding 200 mm were fairly common with one report of over 300 mm. Mie, Osawe (WMO 47663) reported 464.0 mm on the 31st of May (exact period unknown). The following tables include only 24-hour reports exceeding 100 mm. The recording period is the calendar date in local time: UTC + 9 hours. WMO stations in: ---------------- Okinawa ------- No stations recorded rainfall of >100 mm. Japan ----- Prefecture Station WMO Code Rainfall (mm) Date (May) ---------- ------- -------- ------------- ---- Miyazaki Nobeoka 47822 199.5 30th Miyazaki Miyazaki 47830 125.0 30th Nagasaki Izuhara 47800 196.5 30th Nagasaki Fukue 47843 137.5 30th Tokushima Tokushima 47895 147.5 31st Shimane Saigo 47740 152.0 31st Shimane Hamada 47755 107.5 31st Mie Owase 47663 464.0 31st Aichi Irako 47653 110.0 31st Shizuoka Hamamatsu 47654 122.5 31st Shizuoka Omaezaki 47655 216.0 31st Shizuoka Shizuoka 47656 159.5 31st Yamanashi Kawaguchiko 47640 110.5 31st JMA stations (only amounts greater than 200 mm are given): ---------------------------------------------------------- Prefecture Station JMA code Rainfall (mm) Date (May) ---------- ------- -------- ------------- ---------- Miyazaki Hyuga 87181 208 30th Miyazaki Mikado 87206 241 30th Miyazaki Mitate 87046 209 30th Miyazaki Kitakata 87136 287 30th Miyazaki Nakagoya 87126 279 30th Miyazaki Wanitsuka 87436 281 30th Miyazaki Fukase 87461 277 30th Kochi Nakamura 74456 244 30th Kochi Naruyama 74176 212 30th Kochi Sakawa 74166 262 30th Kochi Funato 74237 217 30th Kochi Hongawa 74056 252 31st Kochi Yanase 74151 204 31st Tokushima Kito 71251 224 31st Tokushima Fukuharaasahi 71211 238 31st Wakayama Irokawa 65311 231 31st Mie Kayumi 53231 212 31st Mie Kiinagashima 53326 235 31st Mie Atashika 53401 217 31st Mie Miyagawa 53321 268 31st Mie Mihama 53416 370 31st Shizuoka Amagi 50427 296 31st b. Sustained Wind Measurements ------------------------------ Station Minamidaitojima on Okinawa (WMO 47945; 25.83N, 131.23E; Alt 15 m) recorded a peak MSW of 34 kts from the south-southeast at 0200 UTC on 30 May with a minimum SLP of 991.2 hPa reported an hour later at 0300 UTC. In Japan, Yakushima, Kagoshima (WMO 47836; 30.38N, 130.67E; Alt 36 m) reported a maximum MSW of 31 kts and a SLP of 986.5 hPa on 30 May at 0900 UTC and 1300 UTC, respectively. Aburatsu, Miyazaki (WMO 47835; 31.57N, 131.42E; Alt 3 m) measured a MSW of 37 kts from the northeast at 1300 UTC, 30 May. The station reported a MSLP of 981.5 hPa at 30/1600 UTC. Muruotomisaki, Kochi (WMO 47899; 33.25N, 134.18E; Alt 185 m) recorded a MSW of 61 kts from the east-northeast at 30/1600 UTC. Later, at 31/0600 UTC, a minimum SLP of 990.5 hPa but with winds of only 18 kts was recorded. Staying in Japan, WMO 47892 (Uwajima, Ehime; 33.23N, 132.55E; Alt 2 m) measured a SLP of 984.6 hPa at 30/1900 UTC and 30/2000 UTC, but the sustained wind maximum only reached 27 kts at 0800 UTC, 31 May. Okayama, Okayama (WMO 47768; 34.65N, 133.92E; Alt 3 m) reported a MSW of 30 kts from the east at 30/2200 UTC and a minimum SLP of 988.6 hPa nine hours later. Shionomiski, Wakayama (WMO 47778; 33.45N, 135.77E; Alt 73 m) measured a MSW of 26 kts (from the east) at 30/1700 UTC and a SLP of 993.4 hPa at 31/1000 UTC. Tsu, Mie (WMO 47651; 34.73N, 136.52E; Alt 3 m) recorded east-southeast winds of 34 kts at 30/1900 UTC and a SLP of 993.8 hPa for 2 hours (1200 and 1300 UTC on 31 May). JMA station 65036 (34.28N, 135.00E, Alt 43 m) in Tomogasima, Wakayama, reported near-gales of up to 31 kts for a lengthy period between 0200 UTC to (and including) 0800 UTC, 31 May. c. Peak Gusts ------------- Several stations recorded peak gusts exceeding gale force with a few exceeding storm force and one of hurricane intensity and another just short of hurricane intensity. Peak gusts exceeding 48 kts (24.6 m/sec) include (dates are local time): 30th May: --------- Prefecture Station WMO ID Alt (m) Peak Gust (kts) ----------------------------------------------------------------------- Okinawa Minamidaitojima 47945 28 60 Kagishima Tanegashima 47837 17 48 Kagoshima Naze 47909 3 49 Miyazaki Aburatsu 47835 3 57 Kochi Sukomo 47897 2 50 Fukui Tsuruga 47631 2 61 31st May: --------- Prefecture Station WMO ID Alt (m) Peak Gust (kts) ----------------------------------------------------------------------- Miyazaki Miyazaki 47830 9 52 Kumamoto Asosan 47821 1142 60 Kochi Kochi 47893 1 48 Kochi Muruotomisaki 47899 185 76 Kochi Shimizu 47898 31 64 Ehime Uwajima 47892 2 49 Tokushima Tokushima 47895 2 56 Shimane Saigo 47740 27 51 Shimane Matsue 47741 17 55 Shimane Hamada 47755 19 51 Okayama Okayama 47768 3 51 Hyogo Kobe 47770 5 51 Hyogo Sumoto 47776 109 54 Mie Tsu 47651 3 50 Niigata Aikawa 47602 6 52 d. Observations Highlighted in JMA's Local Warnings --------------------------------------------------- 1. TC Warning #41: Tosashimizu, Kochi, recorded a peak gust of 62 kts at 30/1410 UTC. 2. TC Warning #51: Mihama, Mie, recorded 93 mm of rain during the one-hour period ending at 30/2000 UTC. Also, Owase, Mie, reported 80 mm during the same period. 3. Torrential Rain Warning #1 (after Linfa was declared XT): Omaezaki, Shizuoka, recorded 51 mm of rain during the one-hour period ending at 31/0100 UTC. e. Reconnaissance Aircraft Reports ---------------------------------- Reconnaissance aircraft reported a maximum flight-level wind of 34 kts in the southern quadrant at 0239 UTC, 30 May. The lowest CP extrapolated from 450 m was 983 mb. D. Damage and Casualties ------------------------ The death toll reported from the Philippines currently stands at 41 dead, 16 injured, and 10 are still reported missing. Nine of the 41 killed (in the Iloilo and Bicol Regions), based on data released by the Philippines' National Disaster Coordinating Council (NDCC), were attributed to the flooding caused by the heavy rains generated by the southwest monsoon, enhanced by Linfa/Chedeng. A total of 20 evacuation centres were set up to cope with 2548 persons forced to leave their homes. A total of 2269 houses were damaged and 206 destroyed. Cost estimates so far include: Agriculture/livestock - 66.7 million pesos Fisheries - 83.4 million pesos Infrastructure - 42.9 million pesos NDCC's final report on the effects of Linfa/Chedeng can be found at: Some additional articles on the storm's effects in the Philippines can be found at the following URL: (Report written by Kevin Boyle with significant contributions by Huang Chunliang and Karl Hoarau) TROPICAL STORM NANGKA (TC-06W / STS 0305 / DODONG) 31 May - 4 June ------------------------------------------------ Nangka: contributed by Malaysia, is the Malaysian name for the jackfruit, an oval-shaped yellow fruit very popular locally Dodong: PAGASA name, is a Filipino male nickname A. Storm Origins ---------------- Tropical Storm Nangka formed in a similar position to its predecessor, Tropical Storm Linfa, near 17.8N, 117.2E, or approximately 185 nm west of northern Luzon, Philippines, at 1200 UTC on 31 May (the time of the first warnings from both JTWC and JMA). At this time the system was moving slowly northwestward at 4 kts. PAGASA had been following the fortunes of this system through their bulletins since 31/0000 UTC, dubbing the cyclone Dodong and setting the MSW at 25 kts (10-min avg). HKO also took an interest six hours later with their first written statement at 31/0600 UTC. Initially, the LLCC of TD-06W was difficult to locate due to the weak, shallow nature of the system, but the combination of QuikScat, animated enhanced infrared satellite imagery and microwave satellite images revealed that the centre was organizing slightly south of the 31/1200 UTC position. Therefore, the coordinates of TD-06W were altered accordingly to 17.2N, 116.8E, or 210 nm west of Luzon with the primary rainband now located to the south of the LLCC. The MSW at this time had increased a little to 30 kts, but the microwave data and water vapor satellite images indicated that dry air was entraining into the system from the north and west. PAGASA temporarily halted tropical cyclone warnings on Tropical Depression Dodong at this time. B. Storm History ---------------- By 0000 UTC on 1 June Tropical Depression 06W/Dodong's movement had become a very sluggish northeast crawl at 1 kt. The Prognostic Reasoning issued at this time (by JTWC) called for an acceleration of the system on this northeasterly heading later in the forecast period as TD-06W moved into the controlling influence of the mid-latitude westerlies. The system had a day or so left to intensify, and at 01/0600 UTC, JTWC, JMA, HKO and CWBT all upgraded Dodong to a 35-kt tropical storm. PAGASA resumed warnings on Dodong as a 35-kt storm and NMCC followed with an upgrade to tropical storm status at 01/900 UTC. NMCC had begun monitoring the system as a tropical depression at 01/0000 UTC, as did GRMC (Guangzhou). (Huang Chunliangs's note: It should be noted that once NMCC upgrades a system to a tropical storm, GRMC will begin to copy the bulletins from NMCC. All the Asian TCWCs implement a 10-min avg for the MSW). Tropical Storm Nangka/Dodong began the expected acceleration toward the northeast, and at 01/1800 UTC animated infrared satellite imagery revealed an increase in deep convection over the LLCC. At 0000 UTC on 2 June Nangka was located near 19.9N, 119.2E, or 150 nm southwest of Taiwan, moving northeastward at 10 kts with a MSW of 45 kts near the centre. A peak intensity of 50 kts was reached as it bypassed the island of Taiwan about 64 nm to the southeast at 02/1200 UTC. The forward speed had by then increased to 21 kts. A 02/1144 UTC SSM/I pass revealed an exposed LLCC to the south of the remaining deep convection. The warning issued at 1800 UTC on 2 June downgraded Nangka to tropical depression intensity, noting that the system was moving east- northeastward at 16 kts. The LLCC was partially-exposed 75 nm southwest of the deep convection, and the system was rapidly becoming extra- tropical. The final warning by JTWC was issued at 02/0000 UTC after the system was adjudged to have taken on complete extratropical characteristics and was starting to acquire a frontal system of its own. This final advisory placed the poorly-defined LLCC near 23.0N, 125.2E, or 225 nm southwest of Naha, Okinawa, and moving east-northeastward at 20 kts. JMA's final advisory at 04/0600 UTC placed the LOW near 30N, 136E. HKO and NMCC ceased their warning coverage at 03/0000 UTC and 04/0000 UTC, respectively, while CWBT also stopped writing bulletins at 04/0000 UTC. PAGASA issued no more advisories after 03/0600 UTC. C. Damage and Casualties ------------------------ There are no reports of casualties or damages associated with Tropical Storm Nangka/Dodong. (Report written by Kevin Boyle) ************************************************************************* NORTH INDIAN OCEAN (NIO) - Bay of Bengal and Arabian Sea Activity for May: 1 tropical cyclone of hurricane intensity North Indian Ocean Tropical Activity for May -------------------------------------------- The North Indian Ocean experiences two tropical cyclone seasons each year, one in the spring and the other in the fall, with very little tropical cyclone activity during the months of July-September. During the spring season, May is the month most likely to see tropical activity, and May of 2003 was no exception. The first tropical cyclone of the year formed several hundred miles east of Sri Lanka on 10 May and operated over Bay of Bengal waters until it finally made landfall in Myanmar on the 19th. The system, designated as Tropical Cyclone 01B by JTWC and as BOB0301 by IMD, reached hurricane intensity on the 12th for about 24 hours. After weakening and remaining at minimal tropical storm intensity for several days, the cyclone was rapidly intensifying once again as it made landfall in Myanmar. The report on TC-01B was written by John Wallace--a special thanks to John for his assistance. TROPICAL CYCLONE (TC-01B) 10 - 19 May ------------------------------------ A. Storm Origins ---------------- The disturbance that became Tropical Cyclone 01B may have been evident as early as 6 May as an enhanced region of convection in an active monsoon trough over the Bay of Bengal. Definite cyclonic organization was evident on the 7th, though it waxed and waned over the following days as the disturbance remained nearly stationary. The JTWC's Joint Metoc Viewer (JMV) track picks it up as a depression- strength LOW on the 8th when it was roughly 850 nm southeast of Madras, India. Around this time the system ended its stationary mode and began a persistent and slow north-northeasterly track. The LOW's organization improved on the 10th and JTWC issued their first warning on TC-01B at 10/1200 UTC with an initial warning intensity of 30 kts. According to the JMV track, TC-01B reached tropical storm strength at 1800 UTC that day when located approximately 575 nm south-southeast of Madras. B. Storm History ---------------- The second JTWC warning, at 11/0000 UTC, upped the MSW to 50 kts. The cyclone was then located about 475 nm east-southeast of Madras, or about 375 nm east of Sri Lanka. Conditions for TC-01B's intensification were highly favorable with very warm SSTs and a large, well-defined upper-level ridge with excellent divergence aloft. Things looked as if the cyclone was set to become intense and a possible scourge to the vulnerable Bengal shores. The cyclone strengthened steadily--after a brief hiatus in the trend, its MSW peaked at 65 kts at 1200 UTC on 12 May some 400 nm east of Madras as it plodded steadily towards the East Indian coast. (More discussion about the peak intensity follows in Section E.) The cyclone's star was quick to fall, however. The strong upper-level ridge to its north induced easterly shear across the system on the same day it peaked, bringing it below hurricane/typhoon strength by late on the 13th. Steering currents weakened as well, slowing its forward motion and turning the cyclone onto an erratic, approximately northward course. The synoptic situation did not improve, and by late on the 14th a combination of easterly shear and dry air entrainment had almost completely dissipated the cyclone's convection save for a sheared convective core over its center. The system struggled to maintain minimal tropical storm status from the 14th into the 16th, even as it continued to generate strong convection. This particularly bleak time in TC-01B's life corresponded with a collapse of steering currents that began late on the 14th, and which left the storm quasi-stationary for the next two days. On the 16th, however, TC-01B was allowed to recover as it broke out of the stall and tracked west-southwestward. The system strengthened slightly on the 16th, but faltered again later that day. The cyclone remained weak as the track bent first westward, then northwestward into the 18th, drawing a bead on the Myanmar (Burma) coast. A ridge to its east finally turned TC-01B northward, whereupon it began a belated and final intensification trend, even after having briefly weakened to depression strength on the 18th. The cyclone strengthened quickly once it had the chance; it is perhaps just as well that it made landfall when it did, at roughly 1000 UTC on 19 May, very near Kyaukpyu, Burma, with a MSW of around 50 kts. Tropical Cyclone 01B weakened quickly after landfall due to land interaction and increased shear, and the JTWC issued its last warning on the system at 1800 UTC on 19 May as it broke up over Myanmar roughly 275 nm north-northeast of Yangon (Rangoon). There was no trace of TC-01B's remnants in satellite imagery by the 21st. C. Meteorological Observations ------------------------------ Huang Chunliang sent a few rainfall and wind observations--a thanks to Chunliang for sending the information. Included were a couple of 24-hour rainfall accumulations from Tamilnadu State, India. Pamban measured 57 mm on 13 May (local time). On the 14th (local time), the stations of Parangipettai and Adiramapatnam recorded 70 mm and 98 mm, respectively. A ship with call sign VWTL reported northerly winds of 33 kts at 13/0000 UTC when located near 13.6N, 83.6E. Six hours later the same ship reported northerly winds of 42 kts while located near 12.6N, 82.8E. At 0000 UTC on 16 May ship VWTT, located near 12.5N, 87.2E, reported southwesterly winds of 35 kts. (The averaging period for these winds is unknown.) D. Damage and Casualties ------------------------ There are no reports of damage or casualties in Myanmar associated with the landfall of Tropical Cyclone 01B. The country of Sri Lanka experienced heavy monsoonal rains during early May which led to that nation's most disastrous flooding since 1947 with over 200 persons perishing in the floods and landslides. TC-01B was located a few hundred miles to the east of northern Sri Lanka during this period, but the heavy rains do not appear to be directly associated with the cyclone. Many articles about the flooding and relief efforts can be found at the following URL: E. Discussion ------------- Not surprisingly, TC-01B's peak intensity is a matter of some conjecture. According to the final JMV track, the peak intensity was 65 kts, which translates to an estimated CP of 976 mb using the JTWC's MSW-CP relation chart first worked out by Atkinson and Holliday in 1977. This estimate agrees well with the minimum CP estimate of the IMD (980 mb). The peak MSW at this time, however, is not tabulated, though for data points bracketing the minimum CP, the MSW is estimated at 65 kts. Of course, one must factor in the averaging time the IMD uses for reporting MSW, which is unknown to me. (Editor's Note: The IMD does not attempt to modify the Dvorak scale intensities; hence, a 1-min averaging period is implied.) On the whole, the IMD and JTWC tracks agree well. The track from the Thai Meteorological Department (TMD) is more interesting--it reports the peak MSW of TC-01B as 60 kts from 0300 to 1500 UTC on the 13th, and is slightly more liberal with the intensity on the 14th. If the TMD uses the same MSW averaging period as the JTWC, the agreement is once again very good. If they use a 10-min averaging scheme, however, then the estimated peak 1-min avg MSW goes up to 70 kts. Even so, the overall picture of the estimates from the various agencies show very good agreement on what was otherwise a well-behaved system, even if perhaps difficult to forecast. (Report written by John Wallace with a few additions by Gary Padgett) ************************************************************************* SOUTHWEST INDIAN OCEAN (SWI) - South Indian Ocean West of Longitude 90E Activity for May: 1 tropical cyclone Southwest Indian Ocean Tropical Activity for May ------------------------------------------------ For the second year in a row, a late-season tropical storm formed in the Southwest Indian Ocean and reached tropical cyclone (hurricane) intensity. And for the second consecutive year, Madagascar experienced damage from a late-season tropical cyclone. In May of 2002 Tropical Cyclone Kesiny struck the northern tip of the island nation, causing more than 30 fatalities. In May of 2003, a more intense Tropical Cyclone Manou struck the eastern coast, leaving more than 70 dead and practically destroying the city of Vatomandry. Manou almost reached the intense tropical cyclone level of 90 kts (10-min avg), and was very unusual in that it was a fairly intense cyclone south of the 19th parallel so late in the season. TROPICAL CYCLONE MANOU (MFR-16 / TC-28S) 2 - 10 May ------------------------------------------ Manou: contributed by Madagascar A. Storm Origins ---------------- An area of convection in the Southwest Indian Ocean began to develop around 28 April, and by 1800 UTC on the 29th was located about 400 nm southwest of Diego Garcia. Animated enhanced infrared and multi- spectral satellite imagery revealed a LLCC; deep convection was cyclic. A 200-mb analysis indicated low to moderate vertical shear and moderate diffluence aloft. Twenty-four hours later the disturbance was in the same general area with little change in organization noted. By 1400 UTC on 1 May the system was located approximately 540 nm west-southwest of Diego Garcia. Deep convection continued to organize around the LLCC and outflow was favorable. Strong vertical shear was located to the north and south of the system, but it appeared to be tracking westward away from the effects of the shear. The potential for development was upgraded to fair. At 0800 UTC on 2 May the disturbance was located about 500 nm west- southwest of Diego Garcia. Deep convection was still cyclic, but an upper-level analysis indicated that the system was still located under a ridge axis with favorable outflow. A new area of convection had formed about 450 nm northeast of Antsiranana, Madagascar, with deep convection organizing around a LLCC and with favorable outflow aloft. JTWC assessed the development potential for the new disturbance as fair also. At 1200 UTC MFR issued the first bulletin for the eastern- most system, numbering it as Tropical Disturbance 16, while at 1400 UTC JTWC issued a TCFA for the second, or westernmost disturbance. At 0400 UTC on 3 May, JTWC issued a TCFA for the original disturbance (MFR-16). The system was then centered approximately 630 nm northeast of Mauritius. Deep convection had continued to build over the LLCC, and recent microwave imagery indicated a significant increase in convective organization. JTWC issued the first warning on TC-28S at 1200 UTC, locating the center roughly 530 nm northeast of Mauritius, moving south- southwestward at 9 kts. Animated multi-spectral imagery indicated significant convective bands surrounding an improved LLCC. A low to mid-level ridge to the northeast and the second tropical circulation approximately 400 nm to the northwest were inducing the poleward motion. (A second TCFA was issued for the second disturbance at 1300 UTC.) At 04/0000 UTC JTWC upped the MSW (1-min avg) to 50 kts while MFR upgraded Tropical Disturbance 16 to depression status (30 kts 10-min avg). The system was then located approximately 360 nm northeast of Mauritius and moving southwestward at 15 kts. The second circulation was located about 350 nm to the north-northwest of TC-28S. The system was forecast to gradually assume a westerly track as a mid-level trough to the south and a low to mid-level ridge to the southwest translated eastward. B. Storm History ---------------- Mauritius upgraded the system to Tropical Storm Manou at 04/0600 UTC. MFR estimated the MSW (10-min avg) at 35 kts and Manou remained a minimal 35-kt tropical storm (per MFR's warnings) for a full three days. JTWC reduced the 1-min avg MSW to 45 kts at 1200 UTC and their intensity estimates fluctuated between 35 and 45 kts for the next few days. At 1200 UTC on 4 May Manou's center was located approximately 300 nm north- east of Mauritius. The vertical shear appeared to have lessened with multi-spectral imagery revealing a partially-exposed LLCC to the north- east of the deep convection. The second circulation to the west showed signs of weakening as it drew close to Manou, and JTWC cancelled the TCFA for that system at 1300 UTC. Tropical Storm Manou moved steadily in a general west-southwesterly direction during the 5th, influenced by the low to mid-level ridge to the southwest. The system appeared to weaken some as microwave imagery around 1200 UTC revealed a fully-exposed LLCC northeast of the deep convection. Manou was located about 190 nm north of Mauritius at 0000 UTC on 6 May, moving southwestward at 7 kts. The southwesterly motion was attributed to the influence of a passing trough to the south. Animated infrared imagery suggested that the LLCC had moved closer to the convection. By 1800 UTC the tropical storm was located northwest of Mauritius and had resumed a west-southwesterly track at 9 kts. A synoptic report of 40-kts prompted JTWC to up the intensity to 40 kts from 35 kts on the previous warning. Deep convection had re-organized over the center after weakening earlier in the day. By 0600 UTC on 7 May Tropical Storm Manou was located about 250 nm northwest of Reunion Island, and had continued to strengthen. MFR raised the intensity to 40 kts, and JTWC upped the 1-min avg MSW estimate to 45 kts. Manou continued trekking to the west-southwest as it slowly intensified. At 1800 UTC MFR and JTWC increased the MSW to 45 and 55 kts, respectively. By 08/0600 UTC visible imagery indicated the formation of a small banding eye. MFR upgraded Manou to tropical cyclone (i.e., hurricane) status with the MSW estimated at 70 kts (10-min avg). The cyclone's center at that time was only 40 nm off the east coast of Madagascar, moving west-southwestward at 8 kts. Tropical Cyclone Manou came to a screeching halt at it neared the coast of Madagascar. By 1200 UTC on 8 May the cyclone had reached its peak intensity of 80 kts (10-min avg) with an estimated CP of 952 mb. Gales reached out 80-100 nm around the 24-nm diameter eye--the radius of 50-kt winds was estimated at 35 nm. (Interestingly, JTWC's peak 1-min avg MSW for Manou was lower than MFR's peak 10-min avg intensity. The peak MSW per JTWC's warnings was 75 kts. However, the CI estimates referenced in the JTWC warnings ranged from 75 to 90 kts. The JTWC forecasters in this case chose to follow the lower Dvorak estimates while MFR went with the higher ones.) The eye of Manou was centered only 10 nm off the coast of Madagascar at 1800 UTC, practically stationary. The storm moved very little for the next 12-18 hours, then gradually began to inch southward on the 9th along the western periphery of a mid-level ridge to the east. The eye continued to straddle the coast as Manou drifted southward. The cyclone began to weaken on the 9th due to land interaction and dry air entrainment. MFR downgraded Manou to a 60-kt tropical storm at 09/1200 UTC, and JTWC lowered the 1-min avg MSW to 55 kts in their next warning at 1800 UTC. The system continued to move slowly southward just off the east coast of Madagascar through the remainder of the 9th and on the 10th with MFR downgrading it to tropical depression status at 0600 UTC. By 1800 UTC on 10 May Manou had lost almost all of its deep convection and the LLCC was difficult to locate. Both MFR and JTWC issued their final warnings on Manou at this time with the dissipating center located about 40 nm east of the coast of Madagascar. C. Meteorological Observations ------------------------------ I have a few surface observations sent by Karl Hoarau and Patrick Hoareau--a special thanks to these guys for sending along the infor- mation. St. Brandon Island (WMO 61986; 16.5S, 59.6E; 4 m elevation) experienced winds gusting above gale force for an extended period as Tropical Storm Manou moved slowly by to the north. Peak gusts reached or exceeded 34 kts from 04/0000 UTC through at least 05/1800 UTC (the record ends at that time). The hourly observation with the strongest sustained wind and peak gust was at 04/1400 UTC. The station reported a 10-min avg wind of 40 kts with a maximum gust of 59 kts--the SLP at that time was 998.3 mb. Manou was then centered approximately 60 nm north-northeast of the island. The minimum SLP of 995.0 nm was measured at 05/0000 UTC when the storm's center was about 50 nm north-northwest of St. Brandon. Mauritius also experienced some rather strong gusts from Tropical Storm Manou. Following are listed several reporting stations in Mauritius with the peak gusts experienced during Manou's approach: Le Domaine des Pailles - 58 kts Le Morne - 55 kts Trou aux Cerfs - 49 kts Fort William - 45 kts Nouvelle-Decouverte - 43 kts Bain-Bouf - 43 kts Queen-Victoria - 41 kts Port-Louis - 40 kts Souillac - 39 kts At Vatomandry, Madagascar, a city which was severely damaged by the cyclone, reports indicate that a peak gust of 114 kts was recorded. The same location recorded 227 mm of rain between midnight and 1500 local time on 9 May. The appearance of Manou in satellite imagery, the magnitude of the winds reported in coastal Madagascar, and the level of damage caused by the cyclone (see Section D) all suggest that Manou was a strong Category 2 or possibly Category 3 cyclone on the Saffir/Simpson Scale at the time of its closest approach to Madagascar. D. Damage and Casualties ------------------------ Tropical Cyclone Manou struck a destructive blow to Madagascar. Reports indicate that the city of Vatomandry was almost 90% destroyed. Electricity, telecommunications and water networks were badly damaged, and roads and bridges were destroyed. In Vatomandry around 24,500 homes were destroyed and 47,500 persons left homeless. In Brickaville and Andevoranto, 95% of dwellings were destroyed. Agricultural losses were also high: 80% of the rice crop in the region was destroyed and the corn crop was also severely damaged. The final death toll was placed at 70 with 19 still missing a few weeks after the storm. Also, about 85 persons were reported as suffering injuries related to the cyclone. Over 115,000 persons in and around Vatomandry were adversely affected by Manou. Additional articles concerning the effects of Tropical Cyclone Manou can be found at the following website: E. A Little Climatology ----------------------- Karl Hoarau looked up some statistics on May tropical cyclones in the Southwest Indian Ocean and sent them to me. A thanks to Karl for sharing this information. A May tropical cyclone (hurricane) is not a really rare event in the Southwest Indian Ocean, but they do not occur all that frequently either. Since the beginning of the satellite era, four tropical cyclones of at least 75 kts have formed in the basin: Kesiny, 75 kts on 9 May 2002 at 0900 UTC - 1200 UTC near 10.5S/50.5E Konita, 90 kts on 5 May 1993 at 0000 UTC near 10.5S/68.5E Ikonjo, 75 kts on 18 May 1990 at 0600 UTC near 7.5S/53.7E Lila, 90 kts on 10 May 1986 at 1200 UTC near 16.7S/89.7E Tropical Cyclone Manou is the fifth, and it is the most remarkable one because it is the first time that a tropical cyclone has reached a significant intensity near 19S-20S in May. A very strong vertical wind shear is a usual climatological feature in May in the Southwest Indian, especially near 20S. One last bit of information: only one tropical cyclone is estimated to have reached 100 kts in May in the South Indian Ocean. That one was Tropical Cyclone Rhonda on 14 May 1997 from 0000 UTC to 1200 UTC at the intensiy of 100 kts near 16S/97E (in the AOR of the Perth TCWC). (Report written by Gary Padgett with a contribution by Karl Hoarau) ************************************************************************* NORTHWEST AUSTRALIA/SOUTHEAST INDIAN OCEAN (AUW) - From 90E to 135E Activity for May: 1 tropical LOW Northwest Australia/Southeast Indian Ocean Tropical Activity for May ------------------------------------------ No tropical cyclones formed in waters between 90E and 135E during May. A weak tropical LOW had formed by 8 May about 375 nm northwest of the Cocos Islands. This system was a Southern Hemisphere twin to the more intense Tropical Cyclone 01B in the Bay of Bengal. The LOW drifted east-southeastward, passing just north of the Cocos on the 10th, and was last mentioned in Perth's daily Tropical Weather Outlooks on the 11th when it was located approximately 150 nm east of the islands. No gale warnings were issued, and the potential for tropical cyclone development was rated low each day. Maximum winds likely did not exceed 20-25 kts. ************************************************************************* NORTHEAST AUSTRALIA/CORAL SEA (AUE) - From 135E to 160E Activity for May: No tropical cyclones ************************************************************************* SOUTH PACIFIC (SPA) - South Pacific Ocean East of Longitude 160E Activity for May: 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 from the archive sites listed below. (Note: I do have a limited e-mail distribution list for the track files. If anyone wishes to receive these via e-mail, please send me a message.) 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. Back issues can be obtained from the following websites (courtesy of Michael Bath, Michael V. Padua, Michael Pitt, and Chris Landsea): 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 JTWC now has available on its website the complete Annual Tropical Cyclone Report (ATCR) for 2001 (2000-2001 season for the Southern Hemisphere). ATCRs for earlier years are available also. Recently added was the report for the Southern Hemisphere 2001-2002 season. The URL is: Also, TPC/NHC has available on its webpage nice "technicolor" tracking charts for the 2002 Atlantic and Eastern North Pacific tropical cyclones; also, preliminary storm reports for all the 2002 Atlantic and Eastern North Pacific cyclones are now available, as well as track charts and reports on storms from earlier years. The URL is: A special thanks to Michael Bath of McLeans Ridges, New South Wales, Australia, for assisting me with proofreading the summaries. PREPARED BY Gary Padgett E-mail: garyp@alaweb.com Phone: 334-222-5327 John Wallace (Eastern North Pacific, North Indian Ocean, Western Gulf of Mexico) E-mail: dosidicus@aol.com Kevin Boyle (Eastern Atlantic, Western Northwest Pacific, South China Sea) E-mail: newchapelobservatory@btinternet.com Simon Clarke (Northeast Australia/Coral Sea, South Pacific) E-mail: saclarke@iprimus.com.au ************************************************************************* ************************************************************************* >> Published: 08-17-03 / Typhoon2000.com / Typhoon2000.ph