DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 240559
SWODY1
SPC AC 240557

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1257 AM CDT MON SEP 24 2007

VALID 241200Z - 251200Z

..THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE CNTRL PLAINS AND
UPPER MIDWEST...

..CNTRL PLAINS AND UPPER MIDWEST...
A HIGHLY MERIDIONAL UPPER-LEVEL TROUGH OVER THE ROCKIES WILL BROADEN
TODAY AS A COLD FRONT MOVES SEWD ACROSS THE UPPER MIDWEST AND CNTRL
PLAINS. A SUBTLE CAPPING INVERSION ALONG THE BOUNDARY WILL WEAKEN
QUICKLY TODAY ALLOWING FOR WIDESPREAD THUNDERSTORM DEVELOPMENT THIS
AFTERNOON. THE AMOUNT OF THUNDERSTORMS AND LIFT ALONG THE WRN EDGE
OF THE LOW-LEVEL JET SHOULD ALLOW SEVERAL LINEAR MCS/S TO DEVELOP
ALONG THE BOUNDARY THIS EVENING.

AN ELONGATED BAND OF STRONGER MID-LEVEL FLOW ASSOCIATED WITH THE
UPPER-LEVEL TROUGH WILL BE PRESENT FROM THE CNTRL PLAINS INTO THE
UPPER MIDWEST. THIS WILL CREATE MODERATE VERTICAL SHEAR ALONG THE
ENTIRE LENGTH OF THE BOUNDARY AND WILL BE SUFFICIENT FOR ORGANIZED
THUNDERSTORMS ACROSS THE SLIGHT RISK AREA. THE GREATEST THREAT FOR
SUPERCELLS AND LARGE HAIL SHOULD BE IN THE CNTRL PLAINS WHERE
INSTABILITY IS FORECAST TO BE GREATER AND MORE DIRECTIONAL TURNING
IN THE WIND FIELDS IS FORECAST. WEAKER LARGE-SCALE ASCENT IN SRN NEB
AND NW KS MAY RESULT IN A SLIGHTLY DELAYED INITIATION ALLOWING FOR
MORE DESTABILIZATION. IN ADDITION...A FOCUSED LOW-LEVEL JET IS
FORECAST ACROSS THE CNTRL PLAINS AND THIS MAY RESULT IN A MORE
PERSISTENT SEVERE THREAT IN THE EARLY EVENING.

FURTHER NORTHEAST FROM NW IA TO CNTRL MN...THE CAPPING INVERSION
SHOULD BE GONE BY MIDDAY AND FORCING WILL BE STRONG ENOUGH FOR
WIDESPREAD THUNDERSTORM DEVELOPMENT EARLY THIS AFTERNOON. EVEN
THOUGH DESTABILIZATION SHOULD BE CUT SHORT...UNIDIRECTIONAL WINDS IN
THE BOUNDARY LAYER MAY BE ENOUGH FOR AN ISOLATED WIND DAMAGE THREAT
WITH THE FASTER MOVING BOWING SEGMENTS ALONG THE BOUNDARY. THE
MODELS ALSO FORECAST A SECONDARY AXIS OF INSTABILITY ACROSS ERN IA
EXTENDING SWD INTO NW IL. ALTHOUGH WIND SHEAR WILL BE NOT BE AS
STRONG...VEERED LOW-LEVEL WINDS AND THE INSTABILITY MAY BE ENOUGH
FOR A MARGINAL WIND DAMAGE THREAT THERE AS WELL.

.BROYLES/GRAMS.. 09/24/2007

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