Tropical Storm Allison was a
storm that devastated southeast Texas in June of
the 2001 Atlantic
The first storm of the season, Allison
lasted unusually long for a June storm, remaining tropical or
subtropical for 15 days. The storm developed from a tropical wave in the northern Gulf of Mexico on June 4, 2001, and struck the upper Texas coast
It drifted northward through the state,
turned back to the south, and re-entered the Gulf of Mexico.
continued to the east-northeast, made landfall on Louisiana, then moved across the southeast United States and
the first storm since Tropical Storm Frances
to strike the northern Texas coastline.
The storm dropped heavy rainfall along its path, peaking at over
) in Texas. The worst flooding occurred in Houston, where most of Allison's damage occurred: 30,000
became homeless after the storm flooded over 70,000 houses and
destroyed 2,744 homes.
Downtown Houston was inundated
with flooding, causing severe damage to hospitals and businesses.
Twenty-three people died in Texas. Throughout its entire path,
Allison caused $5.5 billion ($6.7 billion 2008 USD) in
damage and 41 deaths. Aside from Texas, the places worst hit were
Louisiana and southeastern Pennsylvania.
Following the storm, President George
designated 75 counties
along Allison's path as disaster areas (the first time he had to do
so), which enabled the citizens affected to apply for aid. Allison
is the only tropical storm to have its name retired
ever having reached hurricane strength.
A tropical wave moved off the coast of Africa
on May 21, 2001. It moved westward across the Atlantic Ocean, retaining little convection on its way.
moving across South America and the
Sea, the wave entered the eastern North Pacific Ocean on June 1. A low-level circulation developed on June
2, while it was about 230 miles (370 km) south-southeast
Southerly flow forced the system northward, and the wave moved
inland on June 3. The low-level circulation dissipated, though the
mid-level circulation persisted. It emerged into the Gulf of Mexico on June 4, and developed deep convection on its
Early on June 5, satellite imagery suggested
that a tropical depression was forming in the northwest Gulf of
Mexico, which was furthered by reports of wind gusts as high as
60 mph (95 km/h) just a few hundred feet above the
surface, towards the east side of the system.
Tropical Storm Allison on June 5 at peak strength
At 1200 UTC on June 5, the disturbance developed a broad,
low-level circulation, and was classified as Tropical Storm
Allison, the first storm of the 2001 Atlantic hurricane
. Some intensification was projected, though it was
expected to be hindered by cool offshore sea surface temperatures.
Due to the cold-core nature of the center, Allison initially
. Despite this, the storm quickly strengthened
to attain peak sustained winds of 60 mph (95 km/h), with
tropical storm-force winds extending up to 230 miles
(370 km) east of the center, and a minimum central pressure of
. The storm initially moved very
little, and the presence of several small vortices from within the
deep convection caused difficulty in determining the exact center
Later in the day, several different track forecasts arose. One
scenario had the cyclone tracking westward in to Mexico.
projected the storm moving east towards southern Louisiana.
At the time, it was noted that little rain
or wind persisted near the center, but rather to the north and
east. Under the steering currents of a subtropical
ridge that extended in an east–west orientation across the
States, Allison weakened while nearing the Texas coastline,
and struck near Freeport,
Texas with 50 mph (80 km/h) winds.
Inland, the storm rapidly weakened, and the National Hurricane Center
discontinued advisories early on June 6. Shortly after being
downgraded to a tropical depression, surface observations showed an
elongated circulation with a poorly defined center, which had
reformed closer to the deep convection.
depression drifted northward until reaching Lufkin, Texas, where it stalled due to a high pressure system to
its north. While stalling over Texas, the storm dropped
excessive rainfall, peaking at just over 40 inches
(1,033 mm) in northwestern Jefferson County. On June 7, the subtropical ridge off
Florida weakened, while the ridge west of Texas
This steered Tropical Depression Allison to
make a clockwise loop, and the storm began drifting to the
southwest. As the center reached Huntsville,
Texas, a heavy rain band began to back build from
Louisiana westward into Liberty County, Texas, which had caused additional flooding.
the time, the system had a minimum central pressure of about
1004 mb and maximum sustained winds of about .
Late on June 9 and early on June 10, Allison's remnants once again
reached the Gulf of Mexico and emerged over open waters.
once again became nearly stationary about 60 mi (100 km)
south of Galveston, and despite more favorable upper-level winds, it
showed no signs of redevelopment.
Due to dry air and
moderate westerly wind shear
, the storm
transformed into a subtropical cyclone. While the subtropical
depression moved eastward, a new low level circulation redeveloped
to the east, and Allison quickly made landfall on Morgan City,
Louisiana on June 11.
At around the same time, the
surface center reformed to the east-northeast of its previous
location, aligning with the mid-level circulation. Strong thunderstorms redeveloped over the circulation,
and Allison strengthened into a subtropical storm over southeastern
The storm intensified further to attain
sustained winds of 45 mph (70 km/h) and a minimum
barometric pressure of about 1000 mb near Mclain, Mississippi,
accompanied by a well-defined eye
Tropical Storm Allison over North Carolina
The storm was officially downgraded to a subtropical depression at
0000 UTC on June 12. Somewhat accelerating, the depression
tracked to the east-northeast through Mississippi, Alabama, Georgia, and South Carolina before becoming nearly stationary near Wilmington,
The depression drifted through North
Carolina and sped to the northeast for a time in response to an
approaching cold front. Though satellite and radar imagery show the
system was well-organized, the system slowed and moved erratically
for a period of time, executing what appeared to be a small
began tracking in a generally northeasterly direction, and crossed
into the southern Delmarva Peninsula on June 16. The subtropical remnants reached the
Atlantic on June 17, and while located east of Atlantic
City, New Jersey, winds began to restrengthen, and heavy rains
formed to the north of the circulation.
The low was
interacting with a frontal boundary
and started merging with it, as it accelerated to the northeast at
remnants of Allison briefly reintensified to a subtropical storm through baroclinic processes, though it became extratropical while south of Long Island. By later on June 17, the low was situated
off the coast of Rhode
Island, spreading a swath of precipitation over New
England. The remnants of the tropical storm were then
absorbed by the frontal boundary by June 18, and eventually passed
south of Cape Race,
Newfoundland on June 20,
where the extratropical cyclone dissipated.
after the storm formed, officials in Galveston
County, Texas issued a voluntary evacuation for the western end
Island, as the area was not protected by the Galveston Seawall. The ferry from the
island to the Bolivar
Peninsula was closed, while voluntary evacuations were issued
in Surfside in Brazoria County. When the National Hurricane Center issued
the first advisory on Allison, officials issued Tropical Storm
Warnings from Sargent, Texas to
After the storm made landfall, flash flood
watches and warnings were issued for
numerous areas in eastern Texas. During the flood event, the
National Weather Service in Houston issued 99 flash flood warnings
with an average lead time of 40 minutes. With an average lead
time of 24 minutes, the National Weather Service in Lake
Charles, Louisiana issued 47 flash flood warnings.
average lead time of 39 minutes, the National Weather Service
in New Orleans/Baton Rouge issued 87 flash flood warnings, of
which 30 were not followed by a flash flood.
Florida, a shelter opened the day prior to Allison's
movement northward through the area, seven staff members housing
Two other shelters were on standby. Teams
informed citizens in the Florida
of flood dangers.
Storm Allison was a major flood disaster throughout its path from
Texas to the Mid-Atlantic. The worst of the
flooding occurred in Houston, Texas, where over 35 inches (890 mm) of rain
Allison killed 41 people, of which 27 drowned.
The storm also caused over $5 billion in damage
(2001 USD, $6.4 billion 2007 USD), making Allison
the deadliest and costliest tropical storm on record in the United
with waves on top, areas of Galveston Island experienced a wall of water 8 feet
(2.5 m) in height, creating overwash
along the coastline.
The storm caused winds of up to
43 mph (69 km/h) at the Galveston Pier. While Allison was
stalling over Texas, it dropped heavy rainfall across the state.
Minimal beach erosion was reported. Flash flooding continued for days, with
rainfall amounts across the state peaking at just over
40 inches (1,033 mm) in northwestern Jefferson
In the Port of
, a total of 36.99 inches (940 mm) was
reported. Houston experienced torrential rainfall in a short amount
The six-day rainfall in Houston amounted to
38.6 inches (980 mm). The deluge of rainfall flooded
95,000 automobiles and 73,000 houses throughout Harris
County. Tropical Storm Allison destroyed 2,744 homes, leaving
30,000 homeless with residential damages totaling to
$1.76 billion (2001 USD, $2.05 billion
hospitals in the Texas Medical Center, the largest medical complex in the world,
experienced severe damage from the storm, which hit quickly and
with unexpected fury on a Friday evening. The Baylor
College of Medicine experienced major damage, totaling
$495 million (2001 USD, $577 million
The Southwest Freeway, near Downtown Houston, lies under water due
to flooding from Tropical Storm Allison
The medical school lost 90,000 research
animals, 60,000 tumor samples, and 25 years of research
University of Texas Health Science Center at Houston
the street, lost thousands of laboratory animals. Throughout the
Medical Center, damage totaled to over $2 billion
(2001 USD, $2.3 billion 2007 USD).
The underground tunnel
, which connects most large office buildings in downtown
Houston, was submerged, as were many streets and parking garages
adjacent to Buffalo Bayou
. At the
Theatre District, also in downtown, the Houston Symphony, Houston
Grand Opera, and Alley Theater lost millions of dollars of
costumes, musical instruments, sheet music, archives and other
artifacts. By midnight on June 9 nearly every freeway and major
road in the city was under several feet of water, forcing hundreds
of motorists to abandon their vehicles for higher ground.
Despite massive flooding damage to entire neighborhoods there were
no drowning deaths in flooded homes. In the area, there were
12 deaths from driving, 6 from walking, 3 from electrocution,
and 1 in an elevator. Elsewhere in Texas, a man drowned when
swimming in a ditch in Mauriceville. Damage totaled to $5.2 billion
(2001 USD, $6 billion 2007 USD) throughout Texas.
making its first landfall, Allison's large circulation dropped
severe rains on southwest Louisiana.
Days later, Allison hit the state as a
, dropping more
heavy rains to the area. Rainfall totals peaked at 29.86 inches
(758 mm) in Thibodaux, the highest rainfall total in Louisiana from a
tropical cyclone since another Tropical Storm Allison in
Most of the southeastern portion of the state
experienced over 10 inches of rain (255 mm). Winds were
generally light, peaking at 38 mph (61 km/h) sustained in
with gusts to
53 mph (85 km/h) in Bay
. The storm produced a storm surge of
2.5 feet (0.75 m) in Cameron as it was making landfall in Texas.
moving northward through Texas, the outer bands of the storm
produced an F1 tornado near Zachary, damaging several trees and a power line.
man was killed when a damaged power line hit his truck.
When Allison first made landfall, heavy rainfall flooded numerous
houses and businesses. Minor wind gusts caused minor roof damage to
10 houses in Cameron Parish, while its storm surge flooded portions of Louisiana Highway 82.
system returned, more rainfall occurred, flooding over
1,000 houses in St.
, 80 houses in Saint Bernard Parish
hundreds of houses elsewhere in the state. The flooding also
forced 1,800 residents from their homes in East Baton
The deluge left numerous roads impassable,
while runoff resulted in severe river flooding. The Bogue Falaya River in Covington crested past its peak twice to near record
and Comite Rivers
reached their highest levels
since 1983. In addition, the levee along the Bayou Manchac
broke, flooding roadways and
more houses. Damage in Louisiana totaled to $65 million
(2001 USD, $75 million 2007 USD).
Southeast United States
Mississippi, Allison produced heavy rainfall of over
10 inches (255 mm) in one night, while some areas in the
southwestern portion of the state received over 15 inches
Rainfall totals from Allison
The flooding damaged numerous houses and
flooded many roadways. Thunderstorms from the storm produced four
tornadoes, including one in Gulfport, Mississippi that damaged 10 houses. Severe thunderstorms
County damaged 15 houses, destroyed 10, and injured five
Damage in Mississippi totaled to over
$1 million (2001 USD, $1.2 million 2007 USD).
in Alabama was moderate, with areas near Mobile
experiencing more than 10 inches (255 mm).
rainfall closed several roads in Crenshaw
The storm, combined with a high pressure,
produced coastal flooding in southern Alabama. Allison produced an
F0 tornado in southwest Mobile
County that caused minor roof damage and another F0
tornado in Covington County that caused minor damage to six homes and a
storm, combined with a high pressure system, produced a strong
pressure gradient, resulting in strong rip currents off the coast
The currents prompted sirens, which are
normally used for storm warnings, to be activated in Pensacola Beach
. The rip currents
killed 5 off the coast of Florida. Outer rain bands from the storm
dropped heavy rainfall across the Florida Panhandle
of over 11 inches
(280 mm) in one day. The Tallahassee Regional Airport recorded 10.13 inches (257 mm) in
24 hours, breaking the old 24 hour record set in
1969. Throughout the state, Allison destroyed
10 homes and damaged 599, 196 severely, primarily in Leon
Including the deaths from rip currents,
Allison killed eight people in Florida and caused $20 million
(2001 USD, $23 million 2007 USD) in damage.
Georgia, the storm dropped heavy rainfall of 10 inches
(255 mm) in 24 hours in various locations.
deluge caused rivers to crest past their banks, including the
Oconee River at Milledgeville which peaked at 33.7 feet
The rainfall, which was heaviest across the
southwestern portion of the state, washed out several bridges and
roads, and flooded many other roads. Georgia governor Roy Barnes
declared a state of emergency for
seven counties in the state. The storm also spawned two tornadoes.
outer bands produced 10 tornadoes and
several funnel clouds, though most only caused minor damage limited
to a damaged courthouse, snapped trees and downed power
lines. Allison produced from 12 to 16 inches
(305 to 406 mm) of rainfall in North Carolina, closing nearly all roads in Martin
County and damaging 25 homes. The severe flooding
washed out a bridge in eastern Halifax
County and flooded numerous cars.
Wet roads caused
nine traffic accidents throughout the state.
Mid-Atlantic and Northeast United States
Virginia, Allison produced light rainfall, with the
southeastern and south-central portions of the state experiencing
over 3 inches (76 mm).
A tree in a saturated
ground fell over and killed one person. Allison also produced one
tornado in the state. Washington, D.C. experienced moderate rainfall from the storm,
totaling to 2.59 inches (66 mm) in Georgetown. In Maryland, rainfall from Tropical Depression Allison totaled
to 7.5 inches (190 mm) in Denton, closing eleven roads and causing washouts on 41
experienced only minor rainfall from one to two
inches (25 to 50 mm). Damage was light, and no deaths were
reported. In Delaware, the storm produced moderate rainfall, peaking at
4.2 inches (106 mm) in Greenwood.
No damage was reported.
in combination with an approaching frontal boundary, dropped heavy
rainfall across southeastern Pennsylvania, peaking at 10.17 inches (258 mm) in
Chalfont in Bucks County and over 3 inches (76 mm) in portions
of Philadelphia. The rainfall caused rivers to rise, with the
Neshaminy Creek in Langhorne peaking at .
Several other rivers and
creeks in southeastern Pennsylvania crested at over 10 feet
(3 m). The rainfall downed numerous weak trees and power
lines, leaving 70,000 without power during the storm. The flooding
washed out several roads and bridges, including a few SEPTA
rail lines. In addition, the rainfall destroyed
241 homes and damaged 1,386 others. Flooding at a Dodge
dealership totaled 150 vehicles. Hundreds
of people were forced to be rescued from damaged buildings from
flood waters. The flooding dislodged a clothes dryer in the
basement of the "A" building of the Village Green Apartment Complex
in Upper Moreland Township, breaking a natural gas line. The gas
leak resulted in an explosion and an ensuing fire that killed six
people. Firefighters were unable to render assistance as the
building was completely surrounded by floodwaters. Additionally,
one man drowned in his vehicle in a river. Damage in Pennsylvania totaled to $215 million (2001 USD,
$250 million 2007 USD).
Jersey, the storm produced heavy rainfall, peaking at
8.1 inches (205 mm) in Tuckerton. The rains also caused river flooding,
including the north branch of the Metedeconk River in Lakewood which crested at 8 feet (2.5 m).
The flooding, severe at places, closed several roads, including
numerous state highways. Gusty winds of up to 44 mph
(71 km/h) in Atlantic City downed weak trees and power lines, leaving over
13,000 without power.
Several people had to be rescued from
high waters, though no fatalities occurred in the state. Overall
damage was minimal.
Storm Allison caused flash flooding in New York, dropping up to 3 inches (75 mm) of rain
in one hour in several locations and peaking at 5.73 inches
(146 mm) in Granite Springs.
The rains also caused river flooding,
including the Mahwah River
crested at . Allison's rainfall damaged 24 houses and
several stores, while the flooding closed several major highways in
the New York
Overall damage was light, and no
fatalities occurred in New York due to Allison. Similarly, rainfall
in Connecticut peaked at 7.2 inches (183 mm) in Pomfret, closing several roads and causing minor damage to
numerous houses. The Yantic River at Yantic
crested at 11.1 feet (3.4 m), while a state road was
closed when a private dam in Hampton failed from the rainfall. In Rhode Island, Allison produced up to 7.1 inches
(180 mm) of rainfall in North
Smithfield, washing out several roads and houses, and
destroying a log house in Foster.
isolated severe thunderstorm in the outer bands of Allison produced
an F1 tornado in
Worcester and Middlesex Counties in Massachusetts, impacting over 100 trees and damaging one
house and one small camper. A microburst in
Leominster and another in Shirley damaged several trees.
the storm hit two houses, causing significant damage there but
little elsewhere. Allison also produced moderate rainfall in the
state, mainly ranging from 3 to 5 inches (75 to 125 mm).
The rainfall caused drainage and traffic problems. Damage in
Massachusetts totaled to $400,000 (2001 USD, $466,000
Within weeks of the disaster, President George W. Bush declared
75 counties in Texas, southern
Louisiana, southern Mississippi, northwestern Florida, and southeastern Pennsylvania as disaster areas.
The declarations allowed
affected citizens to receive aid for temporary housing, emergency
home repairs, and other serious disaster-related expenses. The
(FEMA) also provided 75% for the cost of
debris removal, emergency services related to the disaster, and
repairing or replacing damaged public facilities, such as roads,
bridges and utilities.
A few weeks after Allison, FEMA opened six disaster recovery
centers across southeast Texas, which provided recovery information
to those who applied for disaster assistance. The American Red Cross
and the Salvation Army
opened 48 shelters at the
peak of need for people driven from their homes, which served
nearly 300,000 meals. The National Disaster Medical
deployed a temporary hospital to Houston with 88
professionals, aiding nearly 500 people. Thirty-five volunteer
services provided aid for the flood victims in Texas, including
food, clothing, and volunteers to help repair the houses. After
nearly 50,000 cars were flooded and ruined, many people
attempted to sell the cars across the country without telling of
the car's history. Following the extreme flooding, a mosquito
outbreak occurred, though FEMA provided
aid to control the problem. By six months after the storm, around
120,000 Texas citizens
applied for federal disaster aid, totaling to $1.05 billion
(2001 USD, $1.22 billion 2007 USD).
Texas, a mosquito outbreak occurred in Louisiana.
Only pesticides acceptable to the US Environmental
and the US Fish and Wildlife
were allowed to be used. FEMA officials warned
homeowners of the dangers of floodwaters, including mold, mildew,
and bacteria. By three months after the storm, just under 100,000
Louisiana citizens applied for federal aid, totaling to over
$110 million (2001 USD, $128 million 2007 USD).
$25 million (2001 USD, $29 million 2007 USD) of
the total was for business loans, while an additional
$8 million was for public assistance for communities and state
agencies. More than 750 flood victims in Florida applied for governmental aid, totaling to
$1.29 million (2001 USD, $1.5 million
2007 USD). In Pennsylvania, 1,670 flood victims applied for federal aid,
totaling to $11.5 million (2001 USD, $13.4 million
2007 USD). $3.4 million (2001 USD,
$4 million 2007 USD) of the total was to replace a
rail bridge over the Sandy Run Creek
extreme destruction, the name Allison was retired in the Spring of
2002, and will never again be used in the Atlantic basin; the 2001 incarnation of Allison is the only
Atlantic tropical system to have its name retired without reaching
The name was replaced with Andrea in the