DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 190713
SWODY3
SPC AC 190712

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0212 AM CDT MON OCT 19 2009

VALID 211200Z - 221200Z

...SYNOPSIS...
AN UPPER TROUGH IS PROGGED TO CONTINUE SHIFTING ACROSS THE CENTRAL
U.S. THIS PERIOD...THOUGH CONSIDERABLE DIFFERENCES EMERGE BETWEEN
THE NAM AND GFS IN THE HANDLING OF THIS FEATURE THROUGH THE DAY 3
PERIOD. WHILE THE NAM MAINTAINS A PROGRESSIVE/PHASED NRN AND SRN
STREAM TROUGH...THE GFS DEPICTS A MUCH SLOWER PROGRESSION OF THE SRN
STREAM FEATURE WHILE THE NRN TROUGH MOVES QUICKLY ACROSS THE UPPER
MS VALLEY AND INTO THE GREAT LAKES.

THESE DIFFERENCES ARE ALSO EVIDENT IN THE SURFACE PATTERN EVOLUTION.
WHILE THE NAM TAKES THE FRONT TO THE WRN GULF COAST REGION BY THE
END OF THE PERIOD...THE GFS -- AS A RESULT OF THE SLOWER HANDLING OF
THE SRN STREAM UPPER FEATURE -- DEPICTS SURFACE WAVE DEVELOPMENT IN
ERN OK ALONG THE FRONT. IN EITHER CASE HOWEVER...BOUNDARY LAYER
MOISTENING/DESTABILIZATION SHOULD BE SUFFICIENT FOR SURFACE-BASED
CONVECTIVE DEVELOPMENT OVER PARTS OF THE S CENTRAL CONUS.

...S CENTRAL AND SERN OK SSEWD TO THE WRN GULF COAST...
SLY LOW-LEVEL FLOW AHEAD OF THE ADVANCING STORM SYSTEM WILL RESULT
IN CONTINUED MOISTURE ADVECTION INTO THE S CENTRAL U.S. WHICH --
COMBINED WITH DAYTIME HEATING -- SHOULD YIELD MARGINAL
DESTABILIZATION. THIS COMBINED WITH LOW-LEVEL ASCENT INVOF THE
FRONT SHOULD RESULT IN CONVECTIVE DEVELOPMENT -- THOUGH GENERALLY
LIMITED IN INTENSITY BY A LACK OF MORE FAVORABLE CAPE.

STILL...A FEW STRONGER STORMS WILL LIKELY EMERGE...AS FAVORABLY
VEERING WINDS WITH HEIGHT RESULT IN SHEAR SUFFICIENT FOR SOME
UPDRAFT ORGANIZATION. WHILE RESULTING POTENTIAL FOR WIND/HAIL DOES
NOT WARRANT SLIGHT RISK INCLUSION ATTM...WILL INTRODUCE LOW /5%/
SEVERE PROBABILITY THIS FORECAST. THREAT SHOULD INITIALLY EXIST
ACROSS PARTS OF OK/TX...AND COULD SPREAD AS FAR E AS THE LOWER MS
VALLEY REGION LATE DEPENDING UPON EWD PROGRESS OF THE SRN STREAM
SYSTEM.

..GOSS.. 10/19/2009

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