SPC AC 080538
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1138 PM CST MON DEC 07 2009
VALID 091200Z - 101200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
NEGATIVELY-TILTED MIDLEVEL TROUGH SITUATED ALONG CYCLONIC SIDE OF
POWERFUL MID/HIGH-LEVEL JET STREAKS WILL LIFT RAPIDLY NEWD THROUGH
THE OH VALLEY...GREAT LAKES AND NERN STATES WITH 12-HR HEIGHT FALLS
EXCEEDING 200 M ALONG SYSTEM TRACK. AT THE SURFACE...ALREADY
INTENSE SURFACE LOW WILL DEEPEN FURTHER WHILE DEVELOPING NEWD
THROUGH THE GREAT LAKES...PRIOR TO OCCLUDING OVER SWRN ONTARIO INTO
SWRN QUEBEC. MEANWHILE...TRAILING COLD FRONT...INITIALLY FROM THE
MIDDLE OH VALLEY TO CNTRL GULF COAST WILL PUSH EWD THROUGH THE
APPALACHIANS AND EVENTUALLY OFF THE ATLANTIC COAST BY WEDNESDAY
NIGHT. TRAILING EXTENSION OF COLD FRONT WILL SAG MORE SLOWLY SWD
THROUGH THE NRN/CNTRL FL PENINSULA.
...MID ATLANTIC COAST INTO NRN FL...
08/00Z MODEL GUIDANCE REMAINS RELATIVELY CONSISTENT IN THE EVOLUTION
OF THE SYNOPTIC-SCALE FEATURES THROUGH THE DAY TWO PERIOD. THE
RAPID NEWD TRANSLATION OF UPPER SYSTEM AND SURFACE LOW WILL RESULT
IN STRONGER ISALLOBARIC FORCING AND DEEPER-LAYER FORCING FOR ASCENT
BECOMING INCREASINGLY REMOVED FROM SYSTEM WARM SECTOR WITH TIME. AS
A CONSEQUENCE...LOW-LEVEL WINDS WILL TEND TO VEER...RESULTING IN
WEAKENING CONVERGENCE ALONG PROGRESSIVE COLD FRONT.
EXPECT CLUSTERS OF TSTMS TO BE ONGOING WEDNESDAY MORNING ALONG/AHEAD
OF COLD FRONT FROM PARTS OF VA SWWD INTO ERN AL AND THE FL PNHDL.
INTERESTINGLY...OPERATIONAL NAM-BMJ...GFS AND SREF ETA-KF CONTROL
MEMBER QPF ALL SUGGEST A GENERAL DECREASE IN CONVECTIVE
PRECIPITATION THROUGH THE DAY FROM CHESAPEAKE BAY SSWWD TO THE
SAVANNAH RIVER WITH MORE PERSISTENT DEEP...MOIST CONVECTION OVER SRN
GA/NRN FL. THIS MAY...IN PART...BE A FUNCTION OF THE WEAKENING DEEP
CONVERGENCE ALONG THE COLD FRONT.
VERTICAL SHEAR WILL REMAIN VERY STRONG ACROSS FRONTAL ZONE
/PARTICULARLY ACROSS THE TIDEWATER REGION SWD THROUGH THE
CAROLINAS/...INDICATING A THREAT FOR DAMAGING WINDS AND PERHAPS
TORNADOES SHOULD TSTMS BECOME SUSTAINED. DUE TO THE UNCERTAINTY OF
THIS CONDITION...ONLY LOW SEVERE PROBABILITIES WILL BE MAINTAINED
ACROSS THIS AREA.
OVER SRN GA/NRN FL...STORMS WILL LIKELY PERSIST THROUGH THE DAY /AS
MENTIONED ABOVE/ WITHIN KINEMATIC ENVIRONMENT FEATURING 35-45 KT OF
DEEP-LAYER SHEAR AND BOUNDARY LAYER DEWPOINTS IN THE 60S. WHILE
ISOLATED SEVERE WEATHER WILL REMAIN POSSIBLE...THE WEAK LAPSE RATES
AND MLCAPE OF GENERALLY LESS THAN 500-700 J/KG SHOULD PRECLUDE MORE
ORGANIZED STORM POTENTIAL.
...UPPER OH VALLEY...
THE POTENTIAL FOR CONVECTIVELY-GENERATED DAMAGING WINDS IN THIS AREA
IS CONDITIONAL ON TSTM DEVELOPMENT. NAM/GOES SIMULATED WATER VAPOR
IMAGERY SUGGESTS THAT REGION WILL RESIDE ON NRN FRINGE OF DRY SLOT
ATTENDANT TO VORTICITY MAXIMUM...POTENTIALLY ALLOWING FOR DEEPER
MIXING AND STEEPENING OF LAPSE RATES THROUGH THE DIURNAL HEATING
CYCLE. A STRONGLY FORCED CONVECTIVE BAND WILL LIKELY DEVELOP ALONG
THE FRONT BY AFTERNOON WITHIN ZONE OF STRONG DCVA IN ADVANCE OF
MIDLEVEL SYSTEM. GIVEN THE EXTREMELY STRONG AMBIENT WIND FIELD AND
VERTICAL SHEAR...ANY DEEPER CONVECTIVE ELEMENTS WILL POSE A DAMAGING
WIND THREAT.
..MEAD.. 12/08/2009
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z
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