SPC AC 191720
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1220 PM CDT TUE MAY 19 2009
VALID 201200Z - 211200Z
...NO SVR TSTM AREAS FORECAST...
...CENTRAL PLAINS...
STRONG SHORTWAVE TROUGH WILL PROGRESS ACROSS THE NRN ROCKIES INTO
THE NRN PLAINS LATE WEDNESDAY WHICH WILL FORCE A SHARP COLD FRONT TO
A POSITION FROM CNTRL MN...SWWD INTO THE NEB PANHANDLE/SERN WY BY
21/00Z. FORECAST MODELS INSIST STRONG BOUNDARY LAYER HEATING WILL
OCCUR AHEAD OF WIND SHIFT ACROSS THE CNTRL HIGH PLAINS INTO SRN SD
WHERE LAPSE RATES SHOULD APPROACH DRY ADIABATIC BY PEAK HEATING.
GIVEN THAT CONVECTIVE TEMPERATURES SHOULD BE REACHED...SCATTERED
THUNDERSTORMS WILL DEVELOP DURING THE 21-00Z TIME FRAME OVER SERN WY
INTO THE NEB PANHANDLE/SRN BLACK HILLS. THIS ACTIVITY SHOULD THEN
SPREAD/DEVELOP ALONG SD/NEB BORDER AS COLD FRONT SURGES SEWD. GIVEN
THAT LOW LEVEL MOISTURE IS EXTREMELY LIMITED ACROSS THE PLAINS ANY
CONVECTION THAT EVOLVES WILL BE EXTREMELY HIGH BASED...THOUGH
ADEQUATELY SHEARED FOR STORM ROTATION. IN FACT...A FEW SUPERCELLS
COULD DEVELOP ACROSS THIS REGION DURING THE LATE AFTERNOON/EARLY
EVENING BUT LIMITED MOISTURE/BUOYANCY WILL PRECLUDE A SLIGHT RISK AT
THIS TIME.
...SOUTHERN FL...
MODELS ARE IN GENERAL AGREEMENT THAT MID LEVEL CIRCULATION WILL
EVOLVE ALONG SRN FRINGE OF ERN U.S. TROUGH...THEN DRIFT WWD ACROSS
SOUTH FL INTO THE ERN GULF OF MEXICO. ATTENDANT SFC LOW WILL
PROGRESS WWD BENEATH THIS MID LEVEL CIRCULATION WHICH WILL RESULT IN
DEEP ELY FLOW ACROSS THE FL PENINSULA. WHILE SHEAR PROFILES WILL
CERTAINLY BE SUPPORTIVE OF WEAK ROTATING STORMS...PER SIGNIFICANT
CLOCKWISE TURNING IN THE SFC-3KM LAYER...FORECAST LAPSE RATES ARE
WEAK AND INSTABILITY IS EXPECTED TO REMAIN SOMEWHAT MARGINAL. EVEN
SO...A FEW SUPERCELLS COULD PRODUCE ISOLATED TORNADOES.
..DARROW.. 05/19/2009
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z
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