Thursday, February 5, 2009

One Year Ago Today!

One year ago today we were watching a serious severe weather episode unfold that would later be known as the “Super Tuesday Outbreak” By early Tuesday Afternoon the Storm Prediction Center placed most of the Mid South Region under a “High Risk” of severe thunderstorms and tornadoes with a moderate risk of severe storms as far west as East Texas. By the end of the day 131 reports of tornadoes and 126 reports of large hail pelted the country.

The atmosphere was increasingly becoming unstable throughout the early afternoon in East Texas as plenty of sunshine helped boost temperatures into the low 80s, almost unheard of for early February. By 4:00PM in the afternoon, a line of scattered supercells exploded along a fast moving cold front through East Texas. Three of these storms would end up producing a significant amount of damage across East Texas through the late afternoon.

By 4:30PM the city of Lindale was being pelted with golfball size hail causing widespread damage to cars and homes. Lindale ISD canceled classes through the end of the week to repair damage to Velma Penny Elementary School and E.J. Moss Intermediate School. This storm later moved north into Upshur County causing strong winds and quarter size hail.

At the same time the second supercell was about to unleash some of the largest hail seen in East Texas. The town of Bullard was crushed by hail up to the size of softballs. This hail damaged numerous cars; yours truly had his car totaled during this storm. While surveying the storm damage with the national weather service, we found houses along Lilly Lane in Bullard where holes were punched through the siding of the home.

Below are a couple a three dimensional views of this storm. Notice on the first image you can see a white core in the center of the cell. The next image it is gone. The first image is showing extremely large hail being held up by the storms updraft. Between the first and second image, the hail became too heavy to hold by the storm's updraft so it fell on the town of Bullard. In order for a storm to hold hail this large above the surface the updraft speed, or wind rising through the storm, to be over 100 mph.

The storm continued to move northeast producing large hail through parts of Smith County. Below is an image of 2.75” hail, or baseball size from my yard about 3 miles northeast of the softball size hail report. Of course I did not get these stones until about 30 minutes after the storm so, they were probably closer to 3 to 3.25” in diameter.

All three of these storms showed strong rotation in the mid levels of the atmosphere and we were under a tornado watch however, with these storms forming along a cold front, the warm surface air you need to produce a tornado was undercut by the rapidly moving cold air underneath these storms. However, as supercell #2 moved through Southeast Smith County, for a brief period of time the circulation of the storm was able to outrun the cold air from the front and produce an EF-1 tornado near Arp along Hwy. 64 East of Tyler. This tornado was on the ground for only about 30 seconds but in that time tore a mile long path of damage snapping trees and damaging a large barn, just missing a home. This is an interesting case of how a tornado can develop, touchdown, and then dissipate in less time than it takes our Doppler radar to make a complete scan. Another good reason to take all severe thunderstorms seriously.

The third supercell developed and moved through Cherokee County producing golfball size hail just east of Jacksonville. This cell also showed strong midlevel rotation however it too was undercut by cold air at the surface.

This storm system later developed into a massive tornado outbreak across the Mid South and Southeast. 2 EF-4 tornadoes touched town in Northern Alabama and dozens of people lost their lives across the Southeast. These storms formed from a combination of a cold winter storm interacting with very warm Gulf air which spread across the southeastern part of the country. With the cold midlevel temperatures combined with the record warmth at the surface, the air mass became very unstable allowing thunderstorms to explode.

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