FORT WORTH HAILSTORM OF 6 MAY 1995

Jennifer Miller

Senior, The Pennsylvania State University, B.S. Candidate in Meteorology

(Manuscript received in final form 26 April 1996 for Meteo 418W)

ABSTRACT

At approximately 0030 UTC on 6 May 1995, softball-sized hail fell in the city of Fort Worth TX accompanied by high winds and flash flooding. Thirteen people were killed and over 100 were injured. This event was caused by a high precipitation supercell which formed in the collision area of two outflow boundaries. The updraft of the supercell was calculated to be over 70 m/s. This paper will analyze the Fort Worth hailstorm and the hours preceding the event by examining the synoptic background, nearby soundings, and the mesoscale environment.


1. INTRODUCTION

A devastating supercell produced 70 mph winds, softball-sized hail, and flash flooding in the Dallas-Fort Worth TX area on the evening of 5 and early 6 May 1995 (Pressley, 1995). Insured damage reached $1 billion, making it one of the insurance industry's 10 costliest disasters (Johns, 1995). This was the third major hailstorm to hit the Dallas-Fort Worth area in early 1995 (Marshall, 1995). Hail up to 3 inches in diameter fell on 25 March 1995 across central Dallas County, and then on 29 April 1995, 4 in. hail was reported at the Dallas-Fort Worth Airport (Marshall, 1995).

As the hail began on the evening of 5 May 1995, 10,000 people were outside for the Mayfest in downtown Fort Worth (Marshall, 1995). The fist-sized hail stones that propelled at 80 mph pelted the crowd causing 3 in. welts (Marshall, 1995). Most people escaped to their cars for shelter, but hail shattered the car windows, showering the occupants with glass and hail (Marshall, 1995). Those remaining outside huddled together, covering their heads and praying aloud (Pressley,1995). Miraculously, no one was killed by the hail, but 90 people were taken to Harris Methodist Fort Worth Hospital for injuries (Pressley,1995).

In Tarrent County alone, which includes Fort Worth, 55,000 homes were left without power (Pressley,1995). Many buildings, homes, and vehicles were severely damaged. Over 80 reports of significant damage to cars and businesses were made to the National Weather Service (NSSFC, 1995). Hardest hit were the three Fort Worth Savings and Loan buildings constructed of tiles (O'Hare, 1995). The main building was nearly leveled, and the other two had many large holes (O'Hare, 1995).

Strong winds of 60 to 70 mph ripped roofs off buildings and caused several building collapses (NSSFC, 1995). A large radio communication tower was blown over, and numerous trees were uprooted and blown down (NSSFC, 1995).

After the hail passed, heavy rain began. As the rain hit the ice, it formed a dense fog (O'Hare, 1995). By the time the rain ended, the city streets of Fort Worth were waist deep in swirling water (O'Hare, 1995). Twelve people were killed by flash flooding, and one by lightning in the Dallas-Fort Worth area (Pressley, 1995). Five drowned in southwest Dallas when rain runoff swept their vehicle into a creek; two were killed when the weight of the rain collapsed a roof at a Dallas clothing plant; and at least three drowned when the strong current of the water sucked them down a storm drain that had lost its manhole cover (Pressley, 1995). (References are provided with original paper.)


Selected Figures

Several outflow boundaries from thunderstorms in Texas and Oklahoma are shown on the surface analysis for 2200 UTC 5 May 1995.

The surface analysis for 0000 UTC 6 May 1995 shows that the intersection of two outflow boundaries is very close to Dallas-Fort Worth. The supercell which produced the large hail at 0030 UTC formed in the region where the two boundaries were intersecting.

A classic supercell sounding is shown in the Fort Worth TX sounding for 0000 UTC 6 May 1995. The region of positive CAPE is shaded in red.