Thursday, December 24, 2009

Discussion NWS Huntsville

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HUNTSVILLE AL
1145 AM CST THU DEC 24 2009

.UPDATE...TO UPGRADE TO HIGH WIND WARNING AND 18Z AVIATION DISCUSSION.
&&

.DISCUSSION...
POTENT UPPER TROF IS DEEPENING OVER N TX WITH THE FIRST OF TWO DRY
SLOTS IDENTIFIED ON WATER VAPOR NOW FOLLOWING BEHIND THE
CONVECTION IN WRN LA. AS THE TROF PIVOTS NE AND BECOMES NEGATIVELY
TILTED...UPPER DIVERGENCE WILL INCREASE SUBSTANTIALLY OVER THE
REGION...ALLOW FOR AGEO-STROPHIC ACCELERATIONS IN LOW LEVELS TO
ENHANCE GRADIENT WINDS. SFC GEOSTROPHIC FLOW IS ALREADY AT 55KT AS
OF 15Z IN N AL. THE 12Z NAM HAS ACCELERATED THE LLJ AT 850 MB TO
85KT BTWN 00-03Z. THERE IS A STRONG ISALLOBARIC COUPLET FORECAST
TO BE ASSOCIATED WITH THE SQUALL LINE AS WELL. ALTHOUGH CRITERIA
MAY FALL SHY IN SOME AREAS...WE FEEL IT IS PRUDENT TO UPGRADE TO
A HIGH WIND WARNING WITH GUSTS OVER OPEN WATER AND HIGHER TERRAIN
TO REACH 55 MPH OR HIGHER. GIVEN WET SOILS BECOMING MORE
SATURATED THIS EVENING...THE THREAT OF DOWNED TREES AND POWER
LINES WILL BE HIGH...MAKING HOLIDAY TRAVEL HAZARDOUS. NO OTHER MAJOR
CHANGES HAVE BEEN MADE AT THIS TIME. WE WILL MONITOR
MOISTURE/INSTABILITY RETURN THIS AFTERNOON IN A NARROW CORRIDOR
AHEAD OF THE SQUALL LINE. GIVEN STRONG 0-1KM SHEAR/SRH...THE
THREAT OF MESO-VORTICES/BRIEF TORNADO THREAT CANNOT BE RULED OUT TOTALLY.
&&
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