SPC AC 180538
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1138 PM CST TUE FEB 17 2009
VALID 191200Z - 201200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
BROAD UPPER TROUGH WILL HAVE BECOME ESTABLISHED OVER THE ERN HALF OF
THE U.S. THURSDAY. SURFACE LOW WILL OCCLUDE OVER THE NERN STATES
WITH COLD FRONT TRAILING SWD ALONG THE ATLANTIC SEABOARD INTO NRN FL
AT THE START OF THIS PERIOD. THE FRONT WILL MOVE SWD THROUGH THE
REMAINDER OF THE PENINSULA DURING THE DAY.
...NRN AND CNTRL FL...
STRONG WLY UNIDIRECTIONAL VERTICAL SHEAR WILL REMAIN IN VICINITY OF
THE FRONT AS IT MOVES THROUGH NRN AND CNTRL FL. BOUNDARY LAYER WINDS
AND DEEP CONVERGENCE SHOULD WEAKEN WITH TIME AS THE LOW LEVEL JET
SHIFTS NEWD THROUGH THE WRN ATLANTIC. SCATTERED CONVECTION WILL
CONTINUE DEVELOPING ALONG AND JUST AHEAD OF THE FRONT AT LEAST INTO
CNTRL FL. GIVEN STRENGTH OF FLOW JUST OFF THE SURFACE AND STRONG
BULK SHEAR...A SEVERE THREAT COULD PERSIST THROUGH THE MORNING WITH
THIS ACTIVITY. LARGEST LOW-LEVEL HODOGRAPHS WILL EXIST INTO MID
MORNING...BUT WILL GRADUALLY DECREASE AS BOUNDARY LAYER WINDS VEER
AND WEAKEN. LIKELIHOOD OF MULTI-LAYER CLOUDS AND WEAK MID-LEVEL
LAPSE RATES SHOULD RESULT IN LOW INSTABILITY ACROSS N CNTRL AND
CNTRL FL. DUE TO LIMITING FACTORS IMPOSED BY THE EXPECTED MARGINAL
THERMODYNAMIC ENVIRONMENT...THE THREAT REMAINS CONDITIONAL...AND
MORE THAN 5% SEVERE PROBABILITIES DO NOT APPEAR WARRANTED AT THIS
TIME. IF IT BECOMES EVIDENT THAT MORE INSTABILITY WILL BE AVAILABLE
THAT CURRENTLY ANTICIPATED...THEN A CATEGORICAL RISK AREA MAY BE
NEEDED IN LATER OUTLOOKS.
S FL WILL PROBABLY EXPERIENCE MORE BOUNDARY LAYER WARMING...BUT
WARMER TEMPERATURES ALOFT AND TENDENCY FOR DEEP CONVERGENCE TO
WEAKEN WITH TIME SUGGEST THE CONVECTION SHOULD UNDERGO AN OVERALL
DECREASE AS IT MOVES INTO THIS REGION.
...ELSEWHERE...
OFFSHORE GULF FLOW AND STABLE CONDITIONS INLAND WILL PRECLUDE
THUNDERSTORM DEVELOPMENT.
..DIAL.. 02/18/2009
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z
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