Thursday, April 14, 2011

4/14 - 7pm - MS/TN/AL Tornado Outbreak Possible Tomorrow

Severe Weather Setup

A potential tornado outbreak is poised to affect Mississippi, Alabama, and Tennessee tomorrow as a rather potent low and associated trough swing through the central part of the nation. Once a warm front passes through the region tomorrow morning and moisture from the south begins to filter in, all forms of severe weather will be possible in North Mississippi, North Alabama, and West Tennessee. I want to place a particular emphasis on Northeast Mississippi and Northwest Alabama, where the greatest risk of tornadoes appears to be at this time. Large hail and damaging winds are possible across the entire region. The Storm Prediction Center has placed these areas under a 45% Moderate Risk of severe weather for tomorrow.

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Timing is going to be difficult to pin down tomorrow as some computer models have slowed down the overall movement of the system. Areas near the Delta in Mississippi could see severe weather late tonight, but the remainder of the state shouldn't see any until the morning and afternoon hours. Here in Starkville it'll most likely be after 11am when we begin to see supercells pop up on the radar and the risk for severe weather could extend well into the early evening hours. West Tennessee will likely see the risk for severe weather develop after noon and extend to just after sunset. NWS Jackson's timeline on the left is a pretty good guess at when things will develop and where tomorrow.


The SPC's Moderate Risk verifies quite well on the computer model forecasts. Ahead of a surface low in Missouri tomorrow, surface winds will become southeasterly in East Mississippi and West Alabama while upper-level winds (500mb) will be quite strong out of the southwest. This will cause quite a bit of directional and speed shear from the lower levels to the upper levels of the atmosphere that will aid in the creation of rotating supercell thunderstorms. These individual cells will most definitely carry a tornado risk as they develop and roll through tomorrow after the noon hour. Dew points in the mid to upper 60's will aid in the creation of these storms and send instability (CAPE) values well over 1500 J/kg in places.

The SREF model's Significant Tornado Parameter will be at a 4 for most of Mississippi tomorrow, but again the ingredients for tornado creation will most likely be at their prime in the eastern half of the state in the afternoon. West Tennessee won't be at quite the high level of risk that Northeast Mississippi/Northwest Alabama will be in tomorrow due to a lessening of moisture and instability as you head northward, but tornadoes, wind, and large hail are still in play tomorrow afternoon.

I will be driving from Starkville to Jackson, TN tomorrow afternoon in preparation for my Saturday morning show at WBBJ-TV. I am going to try and time my departure so that I can possibly intercept a supercell from its southern side as I drive northward. Storm motions of over 40 mph and the poor road network in Northeast Mississippi aren't good for storm chasing, so that's off the table unless something extraordinary happens.

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