Tropical Storm Allison (1989)
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- This article is about Atlantic tropical storm of 1989. For other storms of the same name, see Tropical Storm Allison (disambiguation).
| Tropical storm (SSHS) | ||
|---|---|---|
 Tropical Storm Allison near landfall |
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| Formed | June 24, 1989 | |
| Dissipated | June 28, 1989 | |
| Highest winds |
|
|
| Lowest pressure | 999 mbar (hPa) | |
| Damage | $560 million (1989 USD) $872 million (2005 USD) |
|
| Fatalities | 11 direct | |
| Areas affected |
East Texas, Louisiana | |
| Part of the 1989 Atlantic hurricane season |
||
Tropical Storm Allison was a June 1989 tropical storm that looped over Texas, dropping several inches of rain causing over $800 million in damage to the United States.
Contents |
[edit] Storm history
Three meteorological phenomena combined to produce Tropical Storm Allison. First, Hurricane Cosme moved northward through Mexico in response to a strong mid to upper-level ridge. Its remnants entered the Gulf of Mexico on June 22, when a westward moving tropical wave reached the area. Finally, a strong anticyclone over the Gulf allowed for the disturbed area to organize into Tropical Depression Two in the western Gulf of Mexico on June 24.
The depression continued to organize as it drifted to the north, and became Tropical Storm Allison on June 26 off the Texas coast. A ridge to Allison's north weakened in response to an approaching frontal trough, and the tropical storm accelerated to the north. Allison reached a peak of 50 mph winds just before hitting near Freeport, Texas on the 27th. It turned to the northeast with the front, weakened to a tropical depression on the 27th, and became extratropical on June 28th.
The frontal trough outran the system, and the building ridge to Allison's north forced the extratropical depression turned to the south and southwest. On June 30 Allison completed its loop over the rain-flogged area. The ridge to the north began to erode, allowing Allison to escape Texas by heading to the northeast. Its circulation dissipated on July 1, but the remnants retained some organization, and continued to the northeast.
On July 3 and 4th, the shortwave that was guiding the remnants outran the storm, causing Allison to stall over the Kentucky/Illinois/Indiana border. A second shortwave trough brought Allison, or what was left of it, southward into Alabama. It turned to the west, and completely lost its identity on July 7 over Arkansas, bringing more precipitation to the area.
[edit] Preparations
A tropical storm watch was issued on June 24 for Baffin Bay, Texas to Morgan City, Louisiana which were upgraded to Tropical Storm Warnings on June 26. All advisories were discontinued the next day.
[edit] Impact
While Allison's winds weren't overly strong, it caused tremendous flooding in Texas and Louisiana, with 20-25 inches of rain occurring in some locations. The local hardest hit by the flooding was Winnfield, Louisiana, which experienced almost 30 inches of rain from June 26 to July 1.
Rainfall from the storm extended eastward into the Mid-Atlantic States, producing flooding.[1] In Delaware, the rainfall led to record breaking discharge rates at three gauging stations, while one-third of the state's gauging stations reported significant discharges.[2]
13.9 inches of rain fell at a site in Arkansas, the highest rainfall total from a tropical cyclone in the state.[3]
Eleven people were reported killed from the storm. Three deaths occurred in Texas, five in Mississippi and three in Louisiana. Two teenage boys were killed when their raft got sucked into a drainage pipe from the runoff of Allison in Beaumont, Texas. An eighteen-year-old was killed in Harris County, Texas from drowning during a swim. The eight final deaths in Louisiana and Mississippi were by drowning. The extreme flooding in turn led to heavy damage, amounting to around $560 million (1989 USD, $872 million 2005 USD).
[edit] Lack of retirement
Allison, having replaced Hurricane Alicia, a hurricane that brought heavy damage to southeast Texas, coincidentally caused great damage in the same area. Even more unlikely is that though Allison was not retired, another Tropical Storm Allison in 2001 devastated southeast Texas.
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