DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 301633
SWODY1
SPC AC 301630

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1130 AM CDT TUE APR 30 2013

VALID 301630Z - 011200Z

...THERE IS A SLGT RISK OF SVR TSTMS LATE THIS AFTERNOON INTO
TONIGHT FROM CENTRAL WI ACROSS IA TO NRN KS...

...SYNOPSIS...
MORNING UPPER AIR ANALYSIS AND WV IMAGERY SHOW A MIDLEVEL SHORTWAVE
TROUGH EJECTING NEWD FROM THE NRN PLAINS INTO SRN MANITOBA AND WRN
ONTARIO...WHILE A SECOND UPPER DISTURBANCE IS DIGGING SEWD TOWARD
THE GREAT BASIN. A COLD FRONT ASSOCIATED WITH A SURFACE CYCLONE
LIFTING NWD INTO CANADA EXTENDED SWD INTO IA AND THEN SWWD TOWARD AN
AREA OF SURFACE LOW PRESSURE LOCATED OVER SWRN KS AND THE TX/OK
PANHANDLES. SURFACE LOW PRESSURE WILL BE MAINTAINED OVER THE
CNTRL/SRN HIGH PLAINS THROUGH EVENING AS THE WRN TROUGH CONTINUES TO
AMPLIFY...AND THE FRONT EXTENDING NEWD INTO IA WILL REMAIN
QUASI-STATIONARY DURING THE BULK OF THE FORECAST PERIOD.

...CNTRL PLAINS INTO THE UPPER MS VALLEY THROUGH TONIGHT...
MORNING THUNDERSTORMS FORCED BY LOW-LEVEL WAA REGIME ARE WEAKENING
OVER LOWER MI. IN THEIR WAKE...NEUTRAL MIDLEVEL HEIGHT FALLS WILL
OCCUR THIS AFTERNOON ALONG THE SURFACE COLD FRONT LOCATED FROM THE
UPPER MS VALLEY INTO NRN KS...WHICH IS EXPECTED TO PRECLUDE
THUNDERSTORM DEVELOPMENT UNTIL LATE AFTERNOON INTO THE NIGHT. STRONG
SURFACE SLYS S OF THE FRONT COMBINED WITH TEMPERATURES IN THE 80S
AND MODERATELY AGGRESSIVE BOUNDARY LAYER MIXING WILL YIELD DEWPOINTS
MAINLY IN THE LOW TO MID 50S ALONG THE FRONT. THIS MOISTURE COMBINED
WITH A PLUME OF STEEP MIDLEVEL LAPSE RATES OVERSPREADING THE REGION
WILL RESULT IN MLCAPE VALUES NEAR 1000 J/KG. THIS BUOYANCY COMBINED
WITH WEAKENING CINH ALONG THE FRONT MAY SUPPORT ISOLATED STORM
DEVELOPMENT DURING MID TO LATE AFTERNOON. HOWEVER...COVERAGE IS
EXPECTED TO BE GREATEST DURING THE EVENING/NIGHT AS LARGE SCALE
ASCENT AHEAD OF THE WRN TROUGH INCREASES OVER THE AREA AND
CONVERGENCE ALONG THE FRONT STRENGTHENS WITHIN THE EXIT REGION OF A
NOCTURNAL LOW-LEVEL SLY JET. THOUGH THUNDERSTORMS MAY ULTIMATELY
BECOME LOCATED BEHIND THE FRONT WITH TIME...CAPE AND EFFECTIVE BULK
SHEAR WILL BE SUFFICIENT FOR LARGE HAIL AND PERHAPS DAMAGING WIND
GUSTS.

...SERN LA...
LATE THIS MORNING INTO PART OF THE AFTERNOON...VERY MOIST LOW-LEVEL
AIRMASS WITH DEWPOINTS AROUND 70F EXIST AHEAD OF A LINE OF STORMS
LIFTING NEWD ALONG THE SERN LA COAST. THOUGH SURFACE HEATING WILL
NOT BE PARTICULARLY STRONG DUE TO ANVIL OVERCAST...WEAK TO MODERATE
BUOYANCY...PRECIPITATION LOADING...AND LOW-LEVEL VEERING FLOW MAY
SUPPORT AN ISOLATED THREAT FOR DAMAGING WIND GUSTS.

...W-CNTRL TX THIS AFTERNOON...
ISOLATED THUNDERSTORM DEVELOPMENT WILL BE POSSIBLE ALONG THE DRYLINE
THIS AFTERNOON AS TEMPERATURES WARM INTO THE LOW 90S. DEEPLY MIXED
BOUNDARY LAYER PROFILES WILL SUPPORT THE OCCURRENCE OF DRY
MICROBURSTS AND ISOLATED DAMAGING WIND THREAT.

...CNTRL/SRN FL PENINSULA...
THUNDERSTORMS HAVE ALREADY INITIATED LATE THIS MORNING/EARLY
AFTERNOON OVER THE SRN FL PENINSULA. AIRMASS ACROSS THE AREA IS VERY
MOIST WITH PW VALUES NEAR 1.6 INCHES AND DEWPOINTS IN THE MID 60S TO
LOW 70S...AND MIDLEVEL TEMPERATURES REMAIN FAVORABLY COOL /-9 TO -12
C AT 500 MB/. HOWEVER...EARLY ONSET OF CONVECTION MAY PRECLUDE
STRONG BOUNDARY LAYER DESTABILIZATION. THUS...ANY THREAT OF SEVERE
HAIL/WIND IS EXPECTED TO BE VERY ISOLATED THIS AFTERNOON.

..GARNER.. 04/30/2013

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