Tuesday, March 29, 2011

March 29 Forecast Discussion (Until April 3)

Tomorrow, we will watch two low pressure systems, connected by a trough, slide across the Southeast. In the process, they will create some severe weather as they are creating right now. The lows will eventually combine, then connected by a front. That will intensify these storms.
As they make their way across the board, the low level jet stream will be following their lead. The atmosphere will be unstable from the Gulf up.
Around Pennsylvania, some snow will occur as the precipitation from an extending trough moves towards the coast. The accumulations will be light.
Dry high pressures over the Plains back into the Great Lakes will keep the region cold and sunny, a combination designated for winter.
A low pressure system over the Rockies will be connected to another low in New Mexico. That will be connected to yet another low in Mexico. In all, they will produce light precipitation.

The strong low pressures will move off the Eastern Seaboard after soaking the region. A section of snow and icy conditions will travel up the Northeast. Again, accumulations will be light.
Low pressure will move out of the Rockies, creating abundant precipitation. It will be in the form of mostly rain.
Severe weather will be confined to the state of Florida only. As if they haven't had enough to deal with. Anyways, it appears unlikely that a multi-cell cluster will develop. The same goes for a squall line. At best, several strong, single-celled storms will develop in Central Florida. I would expect a couple of tornadoes at best, but strong winds and small hail are the primary threat.

The Storm Prediction Center is carefully eyeing the Plains for a significant severe weather event. That would occur beyond this forecast's range, but it is something worth mentioning. Because, at the words 'significant severe event', there is a larger concern than just a regular severe weather risk.
A warm-up will occur into the April 2nd period over the Northwest. However, low pressure clippers from Canada will keep the Great Lakes region cold. The Northeast will also be cold.

March 29 Severe Weather Situation

Severe storms are developing in Southern Texas into Louisiana. There are actually 2 severe weather situations, but we will focus more on the tornado watch. Below is an image of real-time radar of that watch.
This watch goes until 10:00pm CDT.
This watch has been issued as single-cell storms have developed into a loosely organized cluster. These storms are generating warnings, and below are those warnings.
The low level jet stream is working its magic across the region, giving the atmosphere a kick of instability. That explains the CAPE values of instability have surpassed 3000 j/kg. That means the atmosphere is at a very good degree of instability.
However, it does appear there isn't much lift within this storm environment.
Vorticity maps indicate that there is negative vorticity, while positive vorticity indicates areas suitable for storm development. Tornadoes are not incredibly likely
But, the Surface Based Lifted Index is at -8, indicating major instability.