Severe Weather Forecast for April 3rd

Because of my involvement with the Arlington EOC, I and other volunteers receive weather-related information directly from the OEM to prepare us for significant weather-related events. Normally we get these early in the morning. That I received the following as a "preliminary briefing" before 5:00 p.m. on the day before indicates considerable concern.

*******

From the Arlington Office of Emergency Management

Scattered showers and thunderstorms are possible tonight. Another active severe weather day also seems to be shaping up for Thursday:

SYNOPSIS - The Storm Prediction Center has placed areas along and north of the I-20 corridor in a moderate risk for severe thunderstorms on Thursday. A slight risk covers our southern counties. Large hail, damaging downbursts, and a few tornadoes are possible, especially in the moderate risk area, Thursday afternoon and evening. Storms will move and spread southeast Thursday night, with the hail and downburst threat continuing.

DISCUSSION - At mid-afternoon Wednesday, a warm front was moving northward into the Temple area. Two vigorous upper level storm systems were to our west...one over the northern Rockies, and one off of the California coast.As we move through Thursday, the warm front will continue through north Texas and into Oklahoma. Warm and moist air will flow north into the area. The upper-level systems will approach the area, with mid and upper level winds increasing. A surface dryline will become established over west Texas, and will move east during the day. A cold front will move southward through Oklahoma as well.Scattered thunderstorms are expected to develop along and ahead of the dryline Thursday afternoon. The atmosphere will be quite unstable, and very strong updrafts will be possible. Deep-layer vertical wind shear will be favorable for organizing the storms, with mid-level rotation. Large hail (perhaps larger than golf balls) and damaging downbursts will be possible from the strongest storms. Storms which can remain isolated, and not merge into clusters or lines, may also find a favorable environment for low-level rotation as well.By Thursday night, the southward-moving cold front should overtake the dryline and move into north Texas. Storms should evolve into a squall line along the front and move south-southeast through the area. The low-level rotation potential should decrease, but the threat for hail and downbursts will continue. Storms should exit our counties late Thursday night or early Friday morning.

BOTTOM LINE - The forecast environment looks fairly similar to what we saw Monday, but the upper-level support should be stronger with this event. Monitor the movement of the dryline and cold front during the day Thursday. Watch for thunderstorm development Thursday afternoon along the front and dryline. Once again, storms may be fairly fast-movers, so teamwork among the spotter groups will be important. Spotter reports of visual storm structure were extremely helpful Monday, and that will be the case Thursday as well. Ground-truth reports will of course be beneficial as well. Monitor the following National Weather Service websites:

http://www.weather.gov/fortworth
(base info)

http://www.spc.noaa.gov/
(Storm Prediction Center)

http://www.srh.noaa.gov/fwd/wcm/embrief.htm
(Emergency Managers briefing page)

for the latest information.