DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 011706
SWODY2
SPC AC 011704

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1204 PM CDT THU AUG 01 2013

VALID 021200Z - 031200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE NRN HIGH PLAINS SEWD
INTO THE LOWER MO RIVER VALLEY...

...SYNOPSIS...
BROAD AREA OF UPPER-LEVEL CYCLONIC FLOW ASSOCIATED WITH A HUDSON BAY
VORTEX WILL RESIDE ACROSS THE ERN CONUS ON FRIDAY. TO THE W...A
MID/UPPER-LEVEL RIDGE WILL BE POSITIONED OVER THE NRN HIGH
PLAINS...AND A POSITIVE TILT UPPER TROUGH WILL BE LOCATED OVER THE
PAC NW. LOW-LEVEL WAA IN THE EXIT REGION OF A SWLY LLJ WILL BE
PRESENT ABOVE A WEAK BAROCLINIC ZONE OVER THE MID MO RIVER VALLEY
DURING THE MORNING...WHICH WILL LIKELY AID IN EARLY PERIOD
THUNDERSTORM ACTIVITY. ELSEWHERE...A SECOND FRONTAL ZONE WILL EXTEND
FROM THE UPPER GREAT LAKES WWD ACROSS SD AND THEN NWWD INTO MT.

AN UPPER DISTURBANCE IS FORECAST TO EMANATE FROM THE TROUGH OVER THE
PAC NW DURING THE AFTERNOON...AND THEN CREST THE UPPER RIDGE BEFORE
MERGING WITH UPPER-LEVEL NWLY FLOW OVER THE UPPER MS RIVER VALLEY.
INCREASING CONVERGENCE ALOFT WILL AID IN STRENGTHENING SURFACE HIGH
PRESSURE DURING THE LATER HALF OF THE FORECAST PERIOD OVER THE NRN
PLAINS...WHICH WILL SUBSEQUENTLY DRIVE THE COLD FRONT SWD INTO THE
CNTRL PLAINS. A MOIST/UNSTABLE AIRMASS COMBINED WITH FRONTAL
CONVERGENCE/ASCENT WILL FAVOR AFTERNOON/EVENING THUNDERSTORM
DEVELOPMENT FROM PORTIONS OF THE NRN HIGH PLAINS INTO THE CNTRL
PLAINS.

...NRN HIGH PLAINS SEWD INTO THE LOWER MO RIVER VALLEY...
THUNDERSTORMS ARE FORECAST TO BE ONGOING AT THE START OF THE PERIOD
FROM PORTIONS OF ERN NEB SWD INTO ERN KS/WRN MO. THE PASSAGE OF A
LOW-AMPLITUDE UPPER WAVE COMBINED WITH BOUNDARY LAYER HEATING AND
DESTABILIZATION MAY ALLOW THIS ACTIVITY TO PERSIST OR RE-INTENSIFY
GOING INTO THE AFTERNOON. STORMS WILL POSE THE GREATEST SEVERE RISK
IN PROXIMITY TO STRONGEST SURFACE HEATING...WHERE LARGE CAPE WILL
EXIST OWING TO THE PRESENCE OF LOW 70S DEWPOINTS. WIND PROFILES ARE
FORECAST TO VEER WITH HEIGHT OVER THIS AREA AND AID IN STORM
ORGANIZATION...WITH LARGE HAIL AND DAMAGING WINDS POSSIBLE.

FARTHER N...MOIST AXIS WILL EXTEND FROM ERN NEB INTO SERN MT DURING
FRIDAY AFTERNOON...WITH DEWPOINTS RANGING FROM THE LOW 70S OVER THE
MID MO RIVER VALLEY TO LOW/MID 50S IN THE NRN HIGH PLAINS. THIS
MOISTURE COMBINED WITH THE PRESENCE OF STEEP MIDLEVEL LAPSE RATES
WILL SUPPORT THE POTENTIAL FOR STRONG INSTABILITY ALONG AND AHEAD OF
THE PREVIOUSLY MENTIONED COLD FRONT. MAGNITUDE OF DESTABILIZATION
AND INSTABILITY IS LESS CERTAIN OVER WRN/CNTRL IA AND NRN MO DUE TO
THE POTENTIAL FOR LINGERING STORMS AND CLOUD COVER DURING MUCH OF
THE MORNING.

CURRENT MODEL GUIDANCE SUGGESTS STORMS WILL DEVELOP DURING EARLY/MID
AFTERNOON ALONG THE FRONT FROM SERN MT INTO SD...AND THEN SPREAD SWD
INTO NEB BY EVENING. BELT OF 70+ KT WNWLY FLOW AT 250 MB OCCURRING
ATOP WEAK LOW-LEVEL ELYS WILL RESULT IN LONG HODOGRAPHS FAVORABLE
FOR SUPERCELL MODES INITIALLY...WITH AN ASSOCIATED RISK FOR LARGE
HAIL/DAMAGING WINDS AND AN ISOLATED TORNADO. THE SWD PROGRESSING
FRONT MAY LEAD TO UPSCALE GROWTH AND MCS DEVELOPMENT LATER IN THE
CONVECTIVE EVOLUTION OVER ERN NEB INTO IA.

..GARNER.. 08/01/2013

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