SPC AC 281956
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0256 PM CDT THU SEP 28 2006
VALID 282000Z - 291200Z
...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON AND TONIGHT FROM
THE MIDDLE ATLANTIC STATES INTO THE SRN APPALACHIANS...
...MIDDLE ATLANTIC STATES INTO SRN APPALACHIANS...
EARLY AFTERNOON WATER VAPOR IMAGERY SHOWS STRONG MID-LEVEL VORTICITY
MAXIMUM DIGGING SEWD THROUGH THE ERN TN VALLEY WITH ATTENDANT 60-80
KT JET STREAK PROPAGATING FROM THE LOWER MS AND SRN TN VALLEY INTO
THE CNTRL APPALACHIANS. IN THE LOW-LEVELS...PRIMARY COLD FRONT WAS
ANALYZED FROM CNTRL NY SSWWD ALONG THE APPALACHIANS INTO CNTRL AL AS
OF 19Z WITH STRENGTHENING LEE TROUGH OVER THE PIEDMONT REGION.
WHILE LOW-LEVEL AIR MASS IS NOT PARTICULARLY MOIST NOR MID-LEVEL
LAPSE RATES VERY STEEP...STRONG HEATING NEAR AND E OF LEE TROUGH HAS
ALLOWED FOR THE DEVELOPMENT OF STEEP LOW-LEVEL LAPSE RATES AND
RESULTANT SBCAPES OF AROUND 1000 J/KG FROM CNTRL MD INTO THE SRN
APPALACHIANS. FARTHER TO THE N...INFLUX OF MOISTURE OFF THE
ATLANTIC COUPLED WITH WEAKER DIABATIC HEATING ARE CONTRIBUTING TO
AIR MASS DESTABILIZATION INTO ERN PA AND NJ.
TSTMS CONTINUE TO INCREASE IN COVERAGE AND INTENSITY THIS AFTERNOON
ALONG BOTH THE COLD FRONT FROM WRN VA INTO NRN GA...AS WELL AS ALONG
LEE TROUGH FROM CNTRL PA/VA TO N OF ATL AS FORCING FOR ASCENT
ASSOCIATED WITH ABOVE MENTIONED VORTICITY MAXIMUM OVERSPREADS
DESTABILIZING AIR MASS. REGIONAL VWPS INDICATE LARGELY SWLY
UNDIRECTIONAL FLOW ACROSS COLD FRONT OVER THE CNTRL AND SRN
APPALACHIANS...WHICH SHOULD SUPPORT A MORE LINEAR CONVECTIVE MODE
WITH THE MAIN THREATS BEING SEVERE HAIL AND DAMAGING WINDS WITH ANY
EMBEDDED BOWS. FOR ADDITIONAL SHORT TERM GUIDANCE ON THIS
AREA...PLEASE SEE MCD 2045.
FARTHER N...ISALLOBARIC RESPONSE TO LOW PRESSURE OVER CNTRL PA IS
RESULTING IN STRONGER LOW-LEVEL SHEAR OVER ERN PA/NJ SWD INTO
CNTRL/ERN MD WHERE POTENTIAL WILL EXIST FOR LOW-TOPPED SUPERCELLS IN
ADDITION TO BOWS CAPABLE OF DAMAGING WINDS...SEVERE HAIL AND PERHAPS
A COUPLE BRIEF TORNADOES. FOR ADDITIONAL SHORT TERM GUIDANCE ON
THIS AREA...PLEASE SEE MCD 2046.
...S/SE TX...
AIR MASS S OF SURFACE FRONT /EXTENDING FROM N OF LCH TO COT TO DRT
AS OF 19Z/ HAS BECOME MODERATELY UNSTABLE THIS AFTERNOON OWING TO
RICH BOUNDARY LAYER MOISTURE AND DAYTIME HEATING WITH MLCAPES OF
1000-2000 J/KG. SUSTAINED FRONTAL CONVERGENCE COUPLED WITH
INCREASED FORCING FOR ASCENT ASSOCIATED WITH SHORT WAVE TROUGH
MOVING OUT OF FAR W TX MAY SUPPORT AN INCREASE IN TSTM DEVELOPMENT
ALONG FRONT LATE THIS AFTERNOON INTO EVENING. LOCAL VWPS AND
PROFILES SUGGEST THE STRONGER DEEP-LAYER VERTICAL SHEAR RESIDES TO
THE N ACROSS POST-FRONTAL AIR MASS...THOUGH THE DEGREE OF
INSTABILITY INDICATES SOME THREAT OF STRONG MULTICELLS CAPABLE OF
MARGINALLY SEVERE WIND/HAIL.
..MEAD.. 09/28/2006
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z
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