National Weather Service United States Department of Commerce
Mesoscale Discussion #0345 issued at 1617 UTC 4 March 2007
MESOSCALE DISCUSSION 0345
NWS STORM PREDICTION CENTER NORMAN OK
1017 AM CST TUE MAR 04 2008
   
AREAS AFFECTED...PARTS OF ERN AL...EXTREME ERN TN...NRN GA INTO
PARTS OF THE WRN CAROLINAS
   
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
VALID 041617Z - 041815Z
   
TIMING ON THE ONSET OF THE MAIN SEVERE THREAT NEAR OR TO THE LEE OF
THE SOUTHERN APPALACHIANS IS STILL A BIT UNCERTAIN.  IT MAY BE
FARTHER EAST...MUCH LATER THIS AFTERNOON/EVENING...BUT TRENDS ARE
BEING MONITORED FOR THE POSSIBILITY OF INCREASING SEVERE POTENTIAL
ACROSS AREA BY 18-21Z.
   
AS A VIGOROUS SHORT WAVE TROUGH CONTINUES TO GRADUALLY LIFT OUT OF
THE LOWER MISSISSIPPI VALLEY...AND TAKE ON AN INCREASING NEGATIVE
TILT...FORCING FOR A FRONTAL OR PRE-FRONTAL SQUALL LINE IS EXPECTED
TO INCREASE ACROSS THE UPPER TENNESSEE VALLEY INTO THE SOUTHERN
APPALACHIANS EARLY THIS AFTERNOON.  CLEARING IN A NARROW PRE-FRONTAL
CORRIDOR...IN THE WAKE OF PRECEDING CONVECTIVE BAND... IS ALLOWING
FOR AT LEAST WEAK HEATING OF A MOIST AND POTENTIALLY POSITIVELY
BUOYANT BOUNDARY LAYER.  HOWEVER...TIME FOR SIGNIFICANT
DESTABILIZATION IS STILL UNCERTAIN...AS AN EASTWARD ACCELERATION OF
THE COLD FRONT MAY OCCUR DURING THE NEXT FEW HOURS.  IF THE FRONT
OVERTAKES THE RAIN COOLED ENVIRONMENT ACROSS EASTERN
TENNESSEE/WESTERN GEORGIA TOO SOON...THE SEVERE THREAT MAY BE
MITIGATED.  NEVERTHELESS...GIVEN THE STRENGTH OF THE PRE-FRONTAL
DEEP LAYER AND LOW-LEVEL SHEAR...POTENTIAL DOES EXIST FOR AN
INCREASING SEVERE THREAT EARLY THIS AFTERNOON...INCLUDING THE RISK
FOR TORNADOES...AS WELL AS DAMAGING WINDS AND SOME HAIL.
   
..KERR.. 03/04/2008
   
   
ATTN...WFO...GSP...MRX...FFC...BMX...HUN...