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Tropical Storm Allison
Tropical Depression Two
Tropical Storm Barry
Tropical Storm Chantal
Tropical Storm Dean
Hurricane Erin
Hurricane Felix
Hurricane Gabrielle
Tropical Depression Nine
Hurricane Humberto
Hurricane Iris
Tropical Storm Jerry
Hurricane Karen
Tropical Storm Lorenzo
Hurricane Michelle
Hurricane Noel
Hurricane Olga

Tropical Cyclone Report

Tropical Storm Allison

5 - 17 June 2001

Stacy R. Stewart
National Hurricane Center
28 November 2001
Revised: 8 February 2002

Tropical Storm Allison developed over the northwestern Gulf of Mexico and moved inland over the upper Texas coast, producing extremely heavy rainfall and catastrophic floods in the Houston area. Allison then acquired subtropical characteristics and continued to produce heavy rainfall and flooding near its track from Louisiana eastward to North Carolina, and then northward along the U.S. east coast to Massachusetts.

a. Synoptic History

Satellite images and synoptic data indicate that Allison originated from a tropical wave that moved off the west coast of Africa on 21 May. The wave tracked westward at about 15 kt across the tropical Atlantic with little associated convection before moving inland over the northern part of South America on 26 May. It emerged over the southwestern Caribbean Sea on 29 May. The wave moved westward into the eastern North Pacific Ocean on 1 June, then slowed down over the Gulf of Tehuantepec. On 2 June, the wave produced a low-level cyclonic circulation centered about 200 n mi south-southeast of Salina Cruz, Mexico.

On 3 June, low- to mid-level southwesterly flow in the southeast quadrant of the Mexican thermal low moved the broad cyclonic circulation inland over extreme southeastern Mexico and western Guatemala. The low-level circulation weakened and became ill-defined after moving inland, whereas the strong mid-level circulation remained intact and tracked northeastward over the southern Yucatan Peninsula early on the 4th. By 0000 UTC 5 June, the mid-level circulation had moved northwestward into the Bay of Campeche of the Gulf of Mexico. Deep convection developed along the western (cyclonic-shear) side of a 30 to 40 kt low-level jet whose axis extended north-northwestward from Merida, Mexico to the Texas-Louisiana border. The deep convection persisted during the night of the 5th and eventually moved north-northwestward around an upper-level cold low centered over south Texas. The difluent eastern semicircle of the upper-level low acted to enhance the development of deep convection.

By 1200 UTC on the 5th, satellite imagery and surface observations suggest that the mid-level circulation developed downward and became Tropical Storm Allison about 120 n mi south of Galveston, TX (see Figure 1 - Figure 3 and Table 1). The cold-core nature of the upper low detected in 0000 and 1200 UTC 5 June upper-air data suggests, however, that this system possessed some subtropical characteristics.

A strong pressure gradient developed between Allison's center and the Atlantic subtropical ridge, which extended westward across Florida and the southeast U.S. and into the northeast Gulf of Mexico. Allison's central pressure dropped and sustained winds increased across a large portion of the central Gulf of Mexico. Winds as high as 40 kt, with gusts to 50 kt, occurred more than 200 n mi east of the center. At 1500 UTC, a ship reported a sustained wind of 43 kt with gusts to 60 kt. (see Table 2) about 90 n mi east of the estimated center location.

Confirmation of a closed circulation came at 1800 UTC when Buoy 42019 (located about 60 n mi south of Freeport, TX) reported a light northwest wind and a pressure of 1006.6 mb just west of the surface center. At 1852 UTC, aircraft personnel on the first U.S. Air Force Reserve reconnaissance flight of the day "closed off" the low-level circulation about 80 n mi south-southwest of Galveston, TX. A combination of a 55 kt flight-level (1500 ft) wind report and the earlier ship reports indicated that the storm had strengthened. The cyclone tracked slowly north-northwestward and weakened slightly (based on offshore buoy reports) just before making landfall southwest of Galveston near Freeport, TX. Its center then tracked slowly northward across the western portions of the Houston metropolitan area during the night of the 5th and the morning of the 6th.

After moving inland, surface observations indicated that Allison quickly weakened to a tropical depression. It drifted slowly northward before becoming stationary over eastern Texas near Lufkin on 7 June. On 8 June, Tropical Depression Allison began to move slowly southward. It eventually moved back over the Gulf of Mexico around 0000 UTC on the 10th, at nearly the same location where it had made landfall as a tropical storm. Although the low-level center remained over warm water on the 10th, very dry air in the mid- and upper-levels of the troposphere overlaid the surface center. The dry air, combined with moderate upper-level westerly shear, inhibited the redevelopment of thunderstorms near the low-level center.

Upper-air observations indicated that by 0000 UTC Allison had acquired some baroclinic characteristics and became a subtropical depression. Most of the persistent deep convection was then developing a couple hundred miles east of the low-level center. A new low-level circulation developed around 0000 UTC 11 June, near the strongest thunderstorms about 150 n mi east of the original center, approximately 50 n mi south of Intracoastal City, LA. By 0200 UTC 11 June, the new center moved inland over southeast Louisiana near Morgan City.

During the early morning hours of the 11th, strong thunderstorms became organized near the low-level circulation center and surface observations indicated that Allison had become a subtropical storm by 0600 UTC. Convection wrapped all the way around the center creating an "eye-like" feature (Figure 4) near 1200 UTC. In spite of the eye-like feature apparent in radar imagery, the cyclone's radius of maximum winds (~100 n mi) was more typical of a subtropical low. Also, surrounding upper-air observations continued to show that Allison was in a weakly baroclinic environment.

The subtropical storm tracked east-northeastward across southern Mississippi. It weakened back to subtropical depression status by 0000 UTC 12 June, when the system was located over southwestern Alabama. It continued to track east-northeastward across southern Alabama, southern Georgia, and southern South Carolina before becoming stationary just north of Wilmington, NC on the 14th. The center of Allison then drifted slowly northward over eastern North Carolina and extreme southeastern Virginia on the 15th. It then moved more quickly northeastward and reached the mid-Atlantic coast on the 17th and eventually cleared the United States mainland along the Delmarva Peninsula later that day. At 1200 UTC 17 June, Allison began to interact with an approaching cold front and briefly strengthened back to a subtropical storm.

Allison merged with the cold front around 0000 UTC 18 June, then becoming an extratropical low pressure system. Shortly after becoming extratropical, the system accelerated east-northeastward before dissipating southeast of Nova Scotia around 0600 UTC 19 June.

b. Meteorological Statistics

Observations in Figure 2 and Figure 3 include satellite-based Dvorak technique intensity estimates from the NOAA Tropical Prediction Center's (TPC) Tropical Analysis and Forecast Branch (TAFB), the NOAA Satellite Analysis Branch (SAB), and the U. S. Air Force Weather Agency (AFWA), as well as data from flights of the 53rd Weather Reconnaissance Squadron of the U. S. Air Force Reserve Command.

Ship reports of tropical storm force winds associated with Allison are in Table 2, and selected surface observations from land stations, C-MAN stations, and data buoys are in Table 3. Allison's peak intensity of 50 kt at 1800 UTC 5 June was based on a 1700 UTC ship (WTEJ) observation of 48 kt and a 55 kt surface wind estimate made by reconnaissance flight crew personnel at 1852 UTC.

During and after Allison's landfall over the upper Texas coast and its southward return to the Gulf of Mexico, extremely heavy rainfall occurred over much of eastern and southeastern Texas, including the Houston metroplex, and much of southwestern Louisiana. Several locations on the east side of Houston received more than 30 inches of rainfall (Figure 5). Heavy rainfall and widespread flooding also occurred with the subtropical low pressure system as it tracked across the southeast and eastern United States (Figure 6).

Evacuations of the west end of Galveston Island were required due to coastal flooding since this area is not protected by the seawall that was built after the Great Hurricane of 1900. Storm surge of 2 to 3 feet, when combined with wave heights up to 8 feet, created considerable overwash. This resulted in significant beach erosion and damage to some of the island's roads. Additional storm surge of 1 to 2 feet occurred over southeast Louisiana on the 11th when Allison passed over that area as a subtropical storm.

A total of 23 tornadoes were confirmed from Mississippi to South Carolina from 11-16 June Specifically, 10 tornadoes were reported in South Carolina, 4 in Mississippi, 3 in Florida, 2 in both Alabama and Georgia, and 1 each in Louisiana and Virginia.

In addition, on 17 June, several sailboats participating in a sailing race from Annapolis, MD to Newport, RI reported sustained winds from the northwest as high as 48 kt and gusts as high as 68 kt at the mouth of Delaware Bay and just off Cape May, NJ. However, the accuracy of these unofficial observations is in doubt since they were not consistent with surrounding official observations. The maximum sustained wind observed was only 31 kt, at Buoy 44009 located just east of the mouth of Delaware Bay. The highest official gust observed during the passage of Subtropical Storm Allison off the U. S. east coast was 36 kt at Atlantic City, NJ. The local pressure gradient along the Delaware and New Jersey coasts also did not support winds as high as those indicated by the sailing vessels. Interestingly enough, though, the brisk winds associated with the subtropical storm resulted in the previous race course record being broken by 5 hours.

c. Casualty and Damage Statistics

Allison's heavy rains produced catastrophic flooding over portions of the upper Texas coastal area, and significant flooding along the remainder of its track. The American Insurance Group reported an insured property loss estimate of $1.22 billion. The TPC standard procedure is to double the insured loss. This results in a final total loss estimate of $2.44 billion. However, damage estimates reported by the Federal Emergency Management Agency (FEMA) and other state emergency management agencies are near $5 billion, with approximately $4.8 billion in the Houston metropolitan area alone. These damage estimates in the Houston area include: $2.04 billion to public facilities (especially the Texas Medical Center), $1.76 billion to residential properties, $1.08 billion to businesses. More than 14,000 homes were destroyed or received major damage, and nearly an additional 34,000 homes incurred at least minor damage. Some of the damage estimates from emergency management agencies may include costs and expenses not directly associated with the flood-related damage.

Forty-one deaths are directly related to the heavy rain, flooding, tornadoes, and high surf generated by Tropical Storm Allison and its remnant subtropical circulation. The death toll by state is as follows: Texas 23, Florida 8, Pennsylvania 7, Louisiana 1, Mississippi 1, and Virginia 1. Twenty-seven of these deaths were due to drowning in freshwater flooding. Early morning on the 11th in Zachary, LA, a tornado (intensity unknown) knocked down trees onto a pickup truck, killing the male driver. Later that morning, an F1 tornado cut a 4 mile long path across George County, MS. It damaged several manufactured homes and completely destroyed a mobile home (tiedowns were pulled out of the ground and the home turned over and fell apart as it rolled), severely injuring a female occupant. There were also 9 indirect deaths in North Carolina as a result of traffic accidents occurring on wet roads. These damage and direct death toll estimates make Allison the deadliest and most costly tropical or subtropical storm on record in the United States.

d. Forecast and Warning Critique

No meaningful track and wind forecast statistics are available due to the limited period for which the National Hurricane Center (NHC) issued forecasts. Since the system reached storm strength quickly, there was little warning lead time. A tropical storm warning was issued at 1900 UTC 05 June from Sargent, Texas eastward along the Gulf of Mexico coast to Morgan City, Louisiana. This was less than 3 hours before tropical storm force winds were reported along the upper Texas coast.A subsequent analysis of satellite and surface observation data indicate that Allison was likely a tropical storm by 1200 UTC 5 June. Determination of a closed surface low pressure system was delayed by at least 6 hours as a result of Buoy 42002 not reporting due to its previous collision with a ship. In addition, Dvorak satellite classifications were not representative of the true intensity of the hybrid system.

After Tropical Depression Allison emerged over the northern Gulf of Mexico, the TAFB issued a gale warning for the northeastern Gulf of Mexico about three hours prior to Allison reaching subtropical storm status. The sustained gale force winds were primarily confined to a thunderstorm squall line in the eastern portion of the low pressure system. The Marine Prediction Center (MPC) in Washington, D.C. also issued gale warnings for portions of the mid-Atlantic offshore waters on 14 and 15 June when Allison was expected to move off the North Carolina and Virginia coasts and possibly reach subtropical storm strength.

Consistent with operational protocol, responsibility for Allison was transferred from the TPC/NHC to the Hydrometeorological Prediction Center (HPC) in Washington, D.C. when the cyclone initially moved inland, weakened to a tropical depression, and coastal warnings were discontinued. By then, the primary threat had become mainly fresh water flooding due to the heavy rainfall.

Operationally, HPC continued to issue products through the remainder of Allison's track. Frequent coordination calls occurred between HPC, TPC, and National Weather Service (NWS) forecast offices during this period of highly-unusual cyclone activity where the system was a tropical depression, subtropical depression/storm, and then an extratropical cyclone. This included the short (12 to 18 hour) period when gale force winds were observed in association with the second center. While this post-storm analysis shows Allison then as a subtropical system (and, hence, technically the forecast responsibility of the TPC/NHC), the decision for the HPC to retain forecast responsibility is supported by the (1) need for consistency in service source, (2) uncertainty in storm type, (3) short duration of gale-force winds, and (4) center remaining mostly over land.


Some of the data in this report was furnished by the National Climatic Data Center in Asheville, NC, various state emergency management agencies, FEMA, National Weather Service Offices in Houston, Lake Charles, New Orleans (Slidell), Mobile, Tallahassee, Jacksonville, Atlanta, Columbia, Charleston, Newport/Morehead City, Raleigh/Durham, Wakefield, Wilmington, Baltimore/Washington, and Mount Holly (Philadelphia), and by the HPC.

Table 1: Best track for Tropical Storm Allison, 5 - 17 June 2001.
Wind Speed
Lat. (°N)Lon. (°W)
05 / 120027.595.0100740tropical storm
05 / 180028.595.3100250"
06 / 000029.395.3100345"
06 / 060030.195.2100630tropical depression
06 / 120031.095.2100520"
06 / 180031.595.0100520"
07 / 000031.695.0100520"
07 / 060031.894.9100620"
07 / 120031.494.9100620"
07 / 180031.195.0100715"
08 / 000030.995.6100215"
08 / 060030.796.1100420"
08 / 120030.496.2100720"
08 / 180030.296.1100720"
09 / 000029.995.9100720"
09 / 060029.695.8100720"
09 / 120029.395.8100720"
09 / 180028.995.6100820"
10 / 000028.695.2100820subtropical depression
10 / 060028.694.7100725"
10 / 120028.794.3100625"
10 / 180028.893.5100630"
11 / 000029.192.3100530subtropical depression (New center)
11 / 060030.090.5100335subtropical storm
11 / 120030.789.4100040"
11 / 180031.088.4100235"
12 / 000031.387.4100425subtropical depression
12 / 060031.886.1100520"
12 / 120032.484.7100620"
12 / 180032.883.6100620"
13 / 000033.182.6100620"
13 / 060033.481.6100425"
13 / 120033.780.7100525"
13 / 180034.079.6100625"
14 / 000034.378.5100625"
14 / 060034.677.9100625"
14 / 120034.777.7100725"
14 / 180034.677.6100825"
15 / 000034.677.2100825"
15 / 060034.977.0100825"
15 / 120035.576.9100825"
15 / 180035.976.8100925"
16 / 000036.376.6100725"
16 / 060036.676.2100725"
16 / 120036.875.9100725"
16 / 180037.275.5100625"
17 / 000037.875.4100625"
17 / 060038.674.5100530"
17 / 120039.373.4100440subtropical storm
17 / 180040.072.1100535"
18 / 000040.670.8100630extratropical low
18 / 060041.369.4100830"
18 / 120042.067.4100930"
18 / 180042.764.6101125"
19 / 000043.561.0101220"
19 / 0600dissipated
05 / 210028.995.3100345landfall near Freeport, TX
11 / 020029.691.6100430landfall near Morgan City, LA
11 / 120030.789.4100040minimum pressure

Table 2: Selected ship reports with winds of at least 34 kt for Tropical Storm Allison, 5-17 June, 2001. "G" indicates peak gust.
Ship Name or Call SignDate/Time (UTC)Lat. (°N)Lon. (°W)Wind dir/speed (deg/kt)Pressure (mb)
KDGR05 / 120025.089.8100 / 34 1008.2 
WTEJ05 / 150027.892.8110 / 43G60 1010.7 
WTEJ05 / 160027.892.7120 / 40 1011.9 
WTEJ05 / 170027.892.6120 / 48 1011.1 
WTEJ05 / 180027.792.5120 / 44 1010.1 
KDGR05 / 180024.588.1110 / 34 1009.4 
WTEJ05 / 190027.692.5120 / 46 1009.9 
WTEJ05 / 200027.692.4120 / 40 1010.2 
WTEJ05 / 210027.592.3150 / 44 1010.5 
WTEJ05 / 220027.492.2140 / 40 1010.0 
WTEJ05 / 230027.492.1140 / 38 1009.9 

Table 3: Tropical Storm Allison selected surface observations, 5 - 17 June 2001.
Maximum Surface Wind Speed
Gust (kts)
(storm total)
Evergreen (KGZH)12/0018 1004.4 11/2201 19 28    
Mobile/Brookley (KBFM)11/1853 1006.55 11/1353 23     
Mobile/Brookley (KBFM)  11/1309  38    
Mobile (KMOB)11/1556 1005.7 11/1230 24 46    
Dover AFB (KDOV)       3.94 
Georgetown (KGED)17/0754 1008.1 17/0954 17 28    
Greenwood       4.08 
Pensacola (KPNS)11/2153 1007.3 11/1346 30 36    
Tallahassee (KTLH)       10.13 
Siloam       5.75 
Acadiana (KARA)06/1047 1010.2 05/1905 24 31    
Alexandria (KAEX)06/2333 1008.8 05/1927 23 33    
Barataria Bay (USGS)  06/0545  37    
Bootheville (KBVE)11/0931 1005.4 11/0920 26 39    
Cameron     2.5   
Door Point (USGS)  11/0400  36    
Grand Pass (USGS)  11/0400  38    
Lake Charles (KLCH)06/0912 1008.5 05/1906 27 31    
Lafayette (KLFT)       15.58 
Morgan City       20.96 
NE Bay Gardene (USGS)  11/0354  46    
NOLa Moisant (KMSY)11/0739 1003.7  24 29    
NOLa Lakefront (KNEW)11/0753 1003.7 11/0854 33 38    
Salt Point (KP92)06/1021 1009.8 05/1305  35   27.55 
Slidell (KASD )11/0905 1002.0  19 28    
Thibodaux       29.86 
WFO Slidell       21.35 
Denton       7.50 
Salisbury (KSBY)17/0754 1007.8 17/1854  23    
KBIX (Keesler AFB)11/1053 1005.3 11/1040 34 55    
KGPT (Gulfport/Biloxi)  11/0914 28 38   11.99 
New Jersey
Absecon       4.60 
Atlantic City (KACY)17/1241 1008.8 17/1246 28 36    
Atlantic City (KACY)  17/1313 21 36    
Atlantic City (KACY)  17/1431 26 34    
Chatham       4.30 
Howell       4.86 
Margate       4.00 
Millville (KMIV)17/0754 1009.4 17/1437  24    
Verga       4.40 
Wertzville       4.33 
North Carolina
Askewville       8.50 
Abington       9.00 
Chanfont       10.17 
Doylestown       9.35 
Horsham       8.00 
Willow Grove (KNXX)       10.16 
South Carolina
Columbia FD       12.00+ 
Alvin       11.23 
Anahuac       12.50 
Angleton (KLBX)06/0223 1004.1 05/2229  23    
Beaumont (KBPT)06/0929 1006.8 05/1520 31 36    
Bellaire       11.25 
Brays Bayou (Stella Link)       19.72 
Brays Bayou (Lawndale)       21.46 
Buffalo Bayou       23.54 
Chigger Creek (Windsong)       18.78 
Clear Creek (Tele. Rd.)       20.04 
College Station (KCLL)06/1014 1006.8      3.49 
Conroe       18.08 
Conroe (KCXO)06/0757 1002.7 06/0444  26   17.48 
Cypress Creek (at Grant)       21.41 
Deer Park       22.99 
Coward Creek (at Baker)       27.95 
Dickinson       14.48 
Eagle Point (port)06/0230 1005.4 05/2130 37 42    
Ellington Field (KEFD)06/0250 1004.4 06/0130 20 44    
Freeport       12.12 
Friendswood       25.98 
Furr H.S. (Harris Co.)       35.14 
Galveston (KGLS)06/0215 1004.4 05/2123 33 40   9.77 
Galveston Bay, N. Jetty06/0012 1002.9 05/2116 35 42 1.8   
Galveston Pleasure Pier06/0130 1003.7 05/2118 38 45 2.1   
Garners Bayou (B'tway 8)       24.61 
Greens Bayou (US 59)       35.76 
Harris Co. Museum N.S.       20.83 
Heights (Harris Co.)       32.00 
Houston Hobby (KHOU)06/0253 1004.4 05/2005 27    18.77 
Houston Hobby (KHOU)  05/2254  33    
Houston Int'cntl (KIAH)06/0413 1003.0 06/0313 21 28   16.48 
Hunting Bayou (Houston)       35.75 
Huntsville (KUTS)06/0943 1003.7      12.16 
Imperial Sugar       15.57 
Jamaica beach06/0100 1004.3      12.13 
Kingwood       21.00 
La Porte       18.86 
League City (NWS HGX)06/0300 1005.6 05/2100  25   19.41 
Little Vince (at Jackson)       22.40 
Missouri City       10.98 
Morgans Point ( port)06/0300 1004.6 06/0318 27 36 1.2   
Palacios (KPSX)06/0048 1005.8 06/0003  24    
Pearland (KLVJ)06/0300 1004.1 05/2216 26 32   21.41 
Pennington       15.60 
Port of Houston       36.99 
Sabine Pass     2.5   
Sugarland (KSGR)06/0336 1005.4 05/2225  25   9.61 
Sugarland City Hall       15.31 
Tomball       16.20 
Tomball (KDWH)06/0559 1003.4 06/0409 21 29   13.14 
Vince Bayou (W. Ellaine)       25.31 
Westheimer (Houston)       33.00 
Westbury       19.53 
White Oak Bayou (Ella)       18.19 
Winnie       16.58 
Wallops Island (KWAL)17/0154 1006.3 16/2103 16 23    
C-MAN Stations
ALSN6 (40.5N 73.8W)17/1800 1010.8 17/1650 28 30    
BURL1 (28.9N 89.4W)11/1100 1004.5 11/1110 41     
BURL1 (28.9N 89.4W)  11/1121  49    
BURL1 (28.9N 89.4W)11/1200 1004.5       
CHLV2 (36.9N 75.7W)16/1000 1007.5 16/1610 33 34    
CLKN7 (34.6N 76.5W)14/0800 1009.1 14/0600  53    
CSBF1 (29.7N 85.4W)  12/0442  35    
DPIA1 (30.3N 88.1W)11/1600 1007.5 11/1420 31 44    
DSLN7 (35.2N 75.3W)14/0900 1013.0 14/1400  36    
GDIL1 (29.3N 90.0W)11/0900 1005.1 11/0850 34 45    
SRST2 (29.7N 94.1W)  05/1450 41 53    
TPLM2 (38.9N 76.4W)16/2100 1011.0       
Moored Buoys
42007 (30.1N 88.8W)  11/1120 34     
42007 (30.1N 88.8W)  11/1108  49    
42019 (27.9N 95.4W)  05/1300 27 33    
42035 (29.3N 94.4W)  05/1500 31 41    
42040 (29.2N 88.2W)11/1100 1008.4 11/1600 33     
42040 (29.2N 88.2W)  11/1541  41    
44004 (38.5N 70.5W)17/2100 1011.7 17/2310 29 33    
44008 (40.5N 69.4W)18/0400 1007.0       
44009 (38.5N 74.7W)17/1000 1004.4 11/1330 31 33    
44011 (41.1N 66.6W)18/1000 1008.8       
44014 (36.6N 74.8W)16/0900 1009.1       
44025 (40.3N 70.2W)17/1800 1008.3 17/1800 27 33    
Oil Rig Platforms
K7B5 (28.1N 93.2W)  05/1400 40 50    
K3B6 (28.0N 92.8W)  10/1445 42     
K7R8 (28.3N 92.0W)  10/1542  35    

Best track positions for Tropical Storm Allison

Figure 1: Best track positions for Tropical Storm Allison, 5-17 June 2001.

Best track maximum sustained surface wind speed curve for Tropical Storm Allison

Figure 2: Best track maximum sustained surface wind speed curve for Tropical Storm Allison, 5-17 June 2001. Aircraft observations have been adjusted for elevation using an 85% reduction factor for observations at 1500 ft. Wind curve is based primarily on surface observations after 1200 UTC 6 June.

Best track minimum central pressure for Tropical Storm Allison

Figure 3: Best track minimum central pressure curve for Tropical Storm Allison, 5-17 June 2001. Pressure curve is based on surface observations after 0600 UTC 6 June. Estimates during the extratropical stage are based on analyses from the NOAA Marine Prediction Center.

1227 UTC 11 June 2001 radar reflectivity image from Mobile, AL

Figure 4: 1227 UTC 11 June 2001 radar reflectivity image from Mobile, AL. Note the eye-like feature over southern Mississippi and the squall line to the east. The intensity was near 40 kt at this time.

Storm total rainfall (in) for the Houston metropolitan area

Figure 5: Storm total rainfall (in) for the Houston metropolitan area (data provided by the Harris Co., TX Office of Emergency Management).

Storm total rainfall for Tropical Storm Allison during the  period 4-18 June 2001

Figure 6: Storm total rainfall for Tropical Storm Allison during the period 4-18 June 2001. Rainfall data were obtained from the standard rainfall reporting network. This map does not include some isolated amounts, which were up to nearly 37 inches.


Last modified: 08-Feb-2002