Monday, February 09, 2009

Severe Weather in Alabama on Wednesday

Many in the weather community have been talking about the possibility of severe weather this week for several days now. This morning a line of strong storms is moving through the Southern Plains. The main action and stormiest weather will move through the nation tomorrow and Wednesday. For Alabama, our greatest risk of severe weather this week appears to be Wednesday afternoon.

The biggest question is whether this will be a severe thunderstorm and straight line wind event with a few small tornadoes or a major tornado outbreak. Some of the ingredients are there for tornadoes. It appears right now that the amount of destabilization out ahead of the front may preclude this from being a major tornado outbreak. The big question will be how much moisture can advance northward ahead of the front.


Usually in a major tornado outbreak, supercells form ahead of the main line and produce violent tornadoes. If there is not enough moisture ahead of the front, the storms advance in a linear fashion, or perhaps in a broken line. In this set up, tornadoes are still possible, but usually not as large, numerous, or damaging.

Having said all of this, it is still a bit early to make a final call on the situation and all residents should be weather aware on Wednesday. If you do not currently own one, this would be an ideal time to purchase a NOAA Weather radio.

Here is an excerpt from the Storm Prediction Center this morning.
GIVEN THE STRENGTH OF EXPECTED FORCING THROUGH THE OHIO AND  
TENNESSEE VALLEYS...AND THE STRENGTH OF THE LOW-LEVEL AND DEEP
LAYER
SHEAR THROUGH MUCH OF THE EASTERN U.S...THE MAGNITUDE
OF WARM SECTOR
DESTABILIZATION APPEARS TO BE THE MAIN UNCERTAINTY
CONCERNING THE
POTENTIAL FOR A MUCH MORE SIGNIFICANT SEVERE
CONVECTIVE EVENT.
FORECAST SOUNDINGS INDICATE THE
NORTHEASTWARD ADVECTION OF AN
ELEVATED MIXED LAYER ACROSS
THE WARM SECTOR THAT COULD PRECLUDE...OR
AT LEAST LIMIT...PRE-
FRONTAL STORM DEVELOPMENT ...AND ALLOW FOR THE
REALIZATION
OF ONLY VERY WEAK CAPE--ON THE ORDER OF A FEW HUNDRED
J/KG--WHERE
THE FRONT STRONGLY FORCES CONVECTIVE DEVELOPMENT. WHILE

THIS COULD MINIMIZE POTENTIAL FOR HAIL...AND PERHAPS THE RISK FOR

TORNADOES...AN APPRECIABLE RISK FOR DAMAGING WIND GUSTS APPEARS TO

EXIST WITH AN ANTICIPATED FRONTAL SQUALL LINE
WEDNESDAY...
PARTICULARLY ACROSS KENTUCKY/TENNESSEE...PARTS OF
INDIANA AND OHIO.


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