DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 241240
SWODY1
SPC AC 241238

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0738 AM CDT WED OCT 24 2012

VALID 241300Z - 251200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM EASTERN NEB INTO PARTS OF
IA...MN...WI...AND UPPER MI...

...UPPER MIDWEST INTO EASTERN NEB...
MORNING WATER VAPOR LOOPS SHOW A FAST-MOVING AND STRONG UPPER TROUGH
MOVING ACROSS PARTS OF CA/NV. THIS FEATURE WILL TRACK EASTWARD INTO
THE CENTRAL ROCKIES BY THIS EVENING. MEANWHILE...A SECOND AND
SMALLER TROUGH OVER WY/MT WILL ROTATE EASTWARD AND AFFECT PARTS OF
THE NORTHERN PLAINS AND UPPER MIDWEST. THE RESULT WILL BE A PERIOD
OF STRONG/SEVERE THUNDERSTORMS THIS AFTERNOON AND TONIGHT FROM
PORTIONS OF NEB/IA INTO MN/WI AND UPPER MI.

THE PRIMARY SURFACE COLD FRONT IS ANALYZED THIS MORNING ROUGHLY FROM
RST-BNW-FNB. THIS BOUNDARY IS FORECAST TO STALL AND BEGIN MOVING
SLOWLY NORTHWARD LATER TODAY AS LOW LEVEL CYCLOGENESIS OCCURS ACROSS
KS/NEB. A STRONG CAPPING INVERSION IS IN PLACE TO THE EAST OF THE
FRONT...WHICH SHOULD EFFECTIVELY CAP THE WARM SECTOR FROM VIGOROUS
CONVECTION THROUGH MOST OF THE DAY. THE PRIMARY THREAT OF STORMS
WILL BE IMMEDIATELY ALONG AND JUST WEST OF THE FRONT THIS EVENING
AND OVERNIGHT.

PRESENT INDICATIONS ARE THAT SCATTERED SHOWERS WILL BEGIN DEVELOPING
IN THE LOW LEVEL WARM ADVECTION REGIME ACROSS PARTS OF IA/SOUTHERN
MN BY EARLY AFTERNOON. HOWEVER...THE BEST CHANCE OF SEEING SEVERE
STORMS WILL BE LATE AFTERNOON AND EVENING AS THE LOW LEVEL JET
STRENGTHENS AND ENHANCES SHEAR/LIFT IN THE IMMEDIATE FRONTAL ZONE.
WHILE SURFACE-BASED STORMS ARE FAR FROM CERTAIN...FORECAST SOUNDINGS
SHOW VERY FAVORABLE LOW LEVEL AND DEEP LAYER VERTICAL SHEAR FOR A
CONDITIONAL THREAT OF SUPERCELLS AND EVEN A FEW TORNADOES. SHEAR
VECTOR ORIENTATIONS SUGGEST THAT ACTIVITY WILL EVOLVE RATHER QUICKLY
INTO A LINEAR STRUCTURE THROUGH THE EVENING.

OVERNIGHT...STORMS SHOULD BECOME MORE NUMEROUS AND DEVELOP
SOUTHWESTWARD INTO PARTS OF EASTERN NEB AND MUCH OF IA. THE SEVERE
THREAT WITH THIS ACTIVITY DOES NOT APPEARS PARTICULARLY HIGH...BUT
SUFFICIENT ELEVATED CAPE ALONG/BEHIND THE COLD FRONT MAY PROMOTE
LARGE HAIL IN THE STRONGER STORMS.

..HART/ROGERS.. 10/24/2012

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