Friday, April 20, 2012

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 200555
SWODY1
SPC AC 200553

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1253 AM CDT FRI APR 20 2012

VALID 201200Z - 211200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF SRN TX...

...SYNOPSIS...

FULL LATITUDE BUT PROGRESSIVE UPPER TROUGH WILL CONTINUE TO AMPLIFY
AND MOVE THROUGH THE MS VALLEY...GREAT LAKES AND SRN PLAINS FRIDAY
PRECEDED BY A COLD FRONT. THIS BOUNDARY WILL STRETCH FROM A SFC LOW
OVER THE GREAT LAKES SWWD INTO SWRN TX 12Z FRIDAY AND CONTINUE TO
ADVANCE EWD AND SEWD. BY 12Z SATURDAY THE FRONT WILL EXTEND FROM THE
NERN STATES SWWD INTO THE WRN GULF.

...SOUTH THROUGH SERN TX...

NEAR SFC DEWPOINTS IN THE UPPER 50S-LOW 60S HAVE ADVECTED INTO SRN
TX BENEATH PLUME OF STEEPER LAPSE RATES. THE ATMOSPHERE WILL
DESTABILIZE FURTHER AS DIABATIC HEATING COMMENCES...AND MLCAPE FROM
1500-2000 J/KG WILL LIKELY DEVELOP IN THIS REGION DURING THE DAY.
PRE-FRONTAL WARM SECTOR WILL LIKELY REMAIN CAPPED TO SFC BASED
STORMS DUE TO PRESENCE OF A WARM EML ALREADY IN PLACE. WITH UPPER
TROUGH AXIS LAGGING BEHIND THE FRONT...SUFFICIENT INSTABILITY AND
DEEP FORCING SHOULD EXIST IN POST FRONTAL ZONE TO INITIATE STORMS.
EFFECTIVE SHEAR OF 40-45 KT WILL PROMOTE A POTENTIAL FOR ORGANIZED
STORMS INCLUDING SUPERCELLS AND BOWING SEGMENTS WITH ISOLATED
DAMAGING WIND AND LARGE HAIL POSSIBLE INTO EARLY EVENING.

...OH VALLEY AREA...

MOISTURE AND INSTABILITY WILL BE MORE LIMITED ALONG NEWD EXTENSION
OF THE FRONT INTO THE OH VALLEY. AS A RESULT THE SEVERE THREAT IN
THIS REGION IS EXPECTED TO REMAIN MORE LIMITED. A FEW STORMS WILL
LIKELY DEVELOP ALONG FRONT OR IN POST FRONTAL REGION WHERE STRONGER
SHEAR WILL RESIDE. A MARGINAL THREAT WILL EXIST FOR ISOLATED STRONG
WIND GUSTS AS ACTIVITY DEVELOPS EWD...BUT COVERAGE OF ANY SEVERE
EVENTS IF THEY OCCUR AT ALL IS EXPECTED TO REMAIN SPARSE.

..DIAL/SMITH.. 04/20/2012

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