DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 270601
SWODY2
SPC AC 270600

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CDT FRI APR 27 2012

VALID 281200Z - 291200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF THE OH
VALLEY...

...SYNOPSIS...

BLOCKY SYNOPTIC PATTERN WILL PREVAIL SATURDAY WITH UPPER RIDGE OVER
THE CNTRL CANADIAN PROVINCES INTO THE UPPER MS VALLEY FLANKED BY AN
UPPER LOW OVER THE NRN ROCKIES AND ERN CANADA. A SRN STREAM
SHORTWAVE TROUGH MOVING INTO THE SRN AND CNTRL HIGH PLAINS AS OF
EARLY FRIDAY MORNING WILL DEAMPLIFY AS IT EJECTS INTO MEAN RIDGE
POSITION THAT WILL BE IN PLACE OVER THE UPPER MS AND OH VALLEYS.

WARM FRONT WILL LIFT NWD TO NEAR THE OH RIVER...BUT NWD PROGRESS
WILL BE IMPEDED BY SFC HIGH PRESSURE CENTERED OVER ONTARIO. THE
EJECTING BUT DEAMPLIFYING WAVE WILL PROVIDE IMPETUS FOR A COLD FRONT
TO SWEEP SEWD. BY THE END OF THE PERIOD THIS BOUNDARY SHOULD EXTEND
FROM THE MID ATLANTIC REGION SWWD INTO NRN TX.

...OH VALLEY AREA...

ELEVATED SHOWERS AND THUNDERSTORMS SHOULD BE IN PROGRESS FROM THE
UPPER MS VALLEY INTO A PORTION OF THE OH VALLEY WITHIN ZONE OF
ISENTROPIC ASCENT NORTH OF WARM FRONT. ACTIVITY WILL SHIFT ENEWD
DURING THE DAY BUT LIKELY REINFORCE THE WARM FRONT AND SLOW ITS NWD
PROGRESS. ATMOSPHERE WILL DESTABILIZE SOUTH OF THIS FEATURE AS AXIS
OF LOW 60S DEWPOINTS ADVECT NEWD BENEATH PLUME OF STEEPER MID LEVEL
LAPSE RATES. LOW CLOUDS SHOULD BEGIN TO DISSIPATE IN WARM SECTOR BY
LATE MORNING OR AFTERNOON ALLOWING THE BOUNDARY LAYER TO DESTABILIZE
WITH MLCAPE TO 1500 J/KG. POTENTIAL WILL EXIST FOR A FEW STORMS TO
REDEVELOP ALONG CONVECTIVELY REINFORCED WARM FRONT...ESPECIALLY FROM
SERN IL...SRN IND INTO THE NRN HALF OF KY WHERE SHORTWAVE RIDGE WILL
BE SUPPRESSED BY THE EJECTING SHORTWAVE TROUGH. THIS REGION WILL
ALSO REMAIN ON NRN FRINGE OF EML WHERE THE CAP SHOULD BE SOMEWHAT
WEAKER THAN FARTHER SOUTH. OTHER STORMS MAY DEVELOP ALONG THE COLD
FRONT AS IT ADVANCES SEWD. SHOULD SFC BASED STORMS DEVELOP...WLY
UNIDIRECTIONAL SHEAR FROM 40-50 KT WILL SUPPORT ORGANIZATION
INCLUDING A FEW SUPERCELLS WITH DAMAGING WIND AND LARGE HAIL THE
MAIN THREATS.


...OK THROUGH THE TX PANHANDLE...

THUNDERSTORM POTENTIAL IS EXPECTED TO REMAIN LIMITED DURING THE DAY
ALONG STALLING FRONT FROM NRN TX INTO THE MID MS VALLEY REGION DUE
TO A CAPPING INVERSION AND WEAK FRONTAL CONVERGENCE.
HOWEVER...STRENGTHENING SLY NOCTURNAL LLJ WILL CONTRIBUTE TO NWD
DESTABILIZATION OVER THE SRN HIGH PLAINS FROM OK INTO THE TX
PANHANDLE. ELEVATED STORMS WILL LIKELY DEVELOP WITHIN THIS ZONE OF
ISENTROPIC ASCENT SATURDAY NIGHT. GIVEN STEEP LAPSE RATES AND
500-1000 J/KG MUCAPE...A FEW OF THE STORMS COULD PRODUCE ISOLATED
HAIL. AT THIS TIME IT APPEARS STORMS WILL PROBABLY REMAIN NORTH OF
THE STRONGER INSTABILITY WHICH MAY LIMIT OVERALL HAIL SIZE.
HOWEVER...THIS AREA MIGHT NEED TO BE INCLUDED IN A SLIGHT RISK IN
LATER OUTLOOKS.

..DIAL.. 04/27/2012

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