SPC AC 311614
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1114 AM CDT TUE JUL 31 2007
VALID 311630Z - 011200Z
...NO SVR TSTM AREAS FORECAST...
...NRN PLAINS...
SURFACE LOW AND ASSOCIATED COLD FRONT WILL CONTINUE TO SHIFT SLOWLY
ESEWD ACROSS THE NRN HIGH PLAINS TODAY. VERY WARM TEMPERATURES WILL
PRECEDE THE FRONT OVER THE WRN/CENTRAL DAKOTAS WITH AFTERNOON HIGHS
WELL INTO THE 90S F. LOW LEVELS REMAIN RATHER MOIST AND SURFACE DEW
POINTS IN THE 50S F SHOULD BE IN PLACE THIS AFTERNOON AFTER DEEP
BOUNDARY LAYER MIXING...SUPPORTING MARGINAL TO MODERATE MLCAPE.
CAPPING SHOULD BE QUITE STRONG GIVEN WARM MID LEVELS TEMPS.
HOWEVER...STRONG HEATING AND INCREASED SURFACE CONVERGENCE SHOULD
ALLOW A FEW HIGH-BASED THUNDERSTORMS TO FORM LATE THIS AFTERNOON AND
EARLY THIS EVENING FROM PARTS OF NERN WY INTO WRN/CENTRAL ND.
ADDITIONAL DEVELOPMENT SHOULD INCREASE NEAR AND JUST BEHIND THE COLD
FRONT INTO SWRN MT/NWRN WY GIVEN MARGINAL INSTABILITY AND UPSLOPE
FLOW. DEEP LAYER FLOW/SHEAR WILL REMAIN WEAK...ALTHOUGH A FEW
STRONG TO BRIEFLY-SEVERE GUSTS AND HAIL MAY ACCOMPANY STRONGER
CORES.
...NRN FL...
DEEP MOIST LAYER ACROSS THE REGION WILL SUSTAIN LARGE AREA OF
MODERATE INSTABILITY THIS AFTERNOON. STALLED SURFACE FRONT
EXTENDING ACROSS NRN FL...AND SEA BREEZE/RESIDUAL OUTFLOW
BOUNDARIES...SHOULD THEREFORE MAINTAIN FOCUS FOR NUMEROUS
THUNDERSTORMS THOUGH THE DAY. A WET MICROBURST OR TWO MAY OCCUR
GIVEN EXTENSIVE WATER LOADING AND MODERATE TO STRONG MLCAPE.
HOWEVER...WEAK FLOW/SHEAR WILL PRECLUDE STORM-SCALE ORGANIZATION AND
RESULT IN BRIEF-LIVED STRONGER CORES.
...AZ...
MID/UPPER LEVEL IMPULSES REMAIN ILL-DEFINED THIS MORNING OVER THE
SWRN U.S. HOWEVER...AIR MASS IS QUITE MOIST WITH SURFACE DEW POINTS
WELL INTO THE 60S F AND 12Z PW/S IN EXCESS OF 1.6 INCHES. AFTERNOON
HEATING SHOULD SUPPORT SCATTERED THUNDERSTORMS ONCE AGAIN TODAY.
GIVEN THE WEAK ENELY WINDS ALOFT...A FEW STORMS WILL DRIFT OFF
HIGHER TERRAIN AND COULD PRODUCE STRONG/BRIEFLY-DAMAGING WINDS.
HOWEVER...OVERALL SEVERE THREAT SHOULD REMAIN MARGINAL.
..EVANS/GUYER.. 07/31/2007
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