SPC AC 071719
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1119 AM CST MON DEC 07 2009
VALID 081200Z - 091200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE CENTRAL GULF
STATES...
...CENTRAL GULF STATES...
PROGRESSIVE UPPER TROUGH WILL TRANSLATE ACROSS THE SRN U.S./PLAINS
INTO THE MS VALLEY REGION LATE AS H5 SPEED MAX IN EXCESS OF 100KT
RACES ACROSS NM INTO AR DURING THE EVENING HOURS. STRONG HEIGHT
FALLS ACROSS THE MID U.S. WILL ENCOURAGE LEE CYCLONE TO INTENSIFY
AND DEEPEN AS IT LIFTS NEWD INTO MO IN CONJUNCTION WITH EJECTING
SPEED MAX. THE NET RESULT WILL BE MASSIVE LARGE SCALE WARM
ADVECTION ATOP A RECOVERING/MODIFYING WARM SECTOR. WIDESPREAD
CLOUDS AND PRECIPITATION WILL CERTAINLY LIMIT INSTABILITY AND LAPSE
RATES SHOULD REMAIN WEAK TO POOR ACROSS MUCH OF THE GULF STATES.
EVEN SO IT APPEARS MODIFIED GULF AIRMASS WILL BEGIN SURGING INLAND
IN RESPONSE TO DEEPENING LOW AND SFC DEW POINTS SHOULD RISE INTO THE
60S ACROSS MUCH OF SERN TX/LA INTO MS/AL BY AFTERNOON. ALTHOUGH
FORECAST INSTABILITY IS EXPECTED TO REMAIN WEAK TO MODEST...VERY
STRONG VERTICAL SHEAR WILL FAVOR LONG-LIVED ROTATING UPDRAFTS AND
POSSIBLE SUPERCELLS. THE MOST LIKELY STORM MODE ATOP RECOVERING
WARM SECTOR WILL BE ELEVATED CONVECTION...ESPECIALLY EARLY AND OVER
THE NRN GULF STATES. WITH TIME SFC WARM FRONT SHOULD SURGE INLAND
ENHANCING THE PROSPECT FOR SFC-BASED SUPERCELL DEVELOPMENT WITHIN
MODIFIED MARITIME TROPICAL ENVIRONMENT. DEEP CONVECTION...WITH
EMBEDDED SUPERCELLS...WILL MIGRATE EWD ACROSS THE GULF STATES IN
RESPONSE TO LARGER SCALE UPPER TROUGH. HOWEVER...STRONGEST FORCING
WILL REMAIN JUST NORTH OF WARM SECTOR WHERE SUFFICIENT INSTABILITY
WILL RESIDE FOR WARM SECTOR SUPERCELLS AND THIS MAY LIMIT OVERALL
COVERAGE OF SEVERE ACROSS THE GULF STATES.
...COASTAL NC...
VERY LATE IN THE PERIOD LARGE SCALE FORCING WILL BEGIN TO OVERSPREAD
THE SRN APPALACHIANS AND CAROLINAS. WEAK SFC FRONT WILL RETURN
INLAND AND ALONG WITH IT A MORE MOIST LOW LEVEL ENVIRONMENT.
FORECAST SOUNDINGS FOR COASTAL NC SUGGEST BOUNDARY LAYER WILL
STRUGGLE TO MOISTEN SUFFICIENTLY FOR MEANINGFUL SFC-BASED
INSTABILITY. EVEN SO...LLJ WILL INCREASE MARKEDLY EAST OF THE
APPALACHIANS AFTER MIDNIGHT AND THIS MAY ENCOURAGE A FEW STRONG
STORMS ALONG LEADING EDGE OF MOISTURE SURGE.
..DARROW.. 12/07/2009
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NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0700Z
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