Thursday, April 15, 2010

DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 150502
SWODY2
SPC AC 150501

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1201 AM CDT THU APR 15 2010

VALID 161200Z - 171200Z

...NO SVR TSTM AREAS FORECAST...

...OH VALLEY...

STRONG HEIGHT FALLS WILL OVERSPREAD THE GREAT LAKES INTO THE OH
VALLEY AHEAD OF SEWD MOVING UPPER TROUGH. LATEST GUIDANCE CONTINUES
TO SUPPORT THE IDEA OF STRENGTHENING MID LEVEL FLOW WITHIN THE BASE
OF DIGGING TROUGH OVER OH/PA BY EARLY EVENING. THIS SHOULD ENHANCE
DEEP LAYER WLY FLOW ALONG ADVANCING FRONTAL BOUNDARY AS IT SURGES TO
A POSITION NEAR THE OH RIVER BY 17/00Z. BOTH THE NAM AND GFS
SUGGEST STRONG BOUNDARY LAYER HEATING WILL OCCUR AHEAD OF WIND
SHIFT...SFC-3KM VALUES APPROACHING 9 C/KM...ENSURING CONVECTIVE
TEMPERATURES WILL BE REACHED BY EARLY AFTERNOON. ALTHOUGH MOISTURE
CONTENT IS A BIT MARGINAL...SFC DEW POINTS WILL RISE INTO THE 50S
WHICH SHOULD YIELD ROUGHLY 500 J/KG SBCAPE FOR ROBUST FAST-MOVING
THUNDERSTORMS AHEAD OF COLD FRONT. AS A RESULT...IT APPEARS AN
EXTENSIVE BAND...OR BANDS...OF FRONTAL CONVECTION WILL EVOLVE FROM
THE UPPER OH VALLEY...SWWD ACROSS MO INTO THE SRN PLAINS WHERE FLOW
WILL BE MUCH WEAKER. AT THIS TIME EXPECTED INSTABILITY MAY BE A BIT
INADEQUATE TO SUPPORT MORE THAN A FEW SEVERE WIND GUSTS. WILL
INTRODUCE 5% PROBS TO ACCOUNT FOR WIND THREAT WITH DEEP CONVECTION
THAT EVOLVES ALONG/AHEAD OF WIND SHIFT...PRIMARILY NORTH AND WEST OF
THE HIGHER TERRAIN. HOWEVER...IF INSTABILITY INCREASES MORE THAN
MODELS SUGGEST A SLIGHT RISK MAY BE WARRANTED IN LATER OUTLOOKS.

..DARROW.. 04/15/2010

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