DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 260602
SWODY2
SPC AC 260600

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CDT FRI APR 26 2013

VALID 271200Z - 281200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM A PORTION OF ERN TX INTO
THE LOWER MS VALLEY REGION...

...SYNOPSIS...

A SRN STREAM SHORTWAVE TROUGH LOCATED NEAR THE 4 CORNERS REGION AND
EMBEDDED WITHIN A QUASI-ZONAL UPPER FLOW REGIME WILL MOVE TO THE
MID-LOWER MS VALLEY BY EARLY SATURDAY. THIS FEATURE WILL CONTINUE
SLOWLY EWD INTO THE TN VALLEY AND SERN STATES. SATURDAY MORNING A
COLD FRONT SHOULD STRETCH FROM WEAK SFC LOW OVER ARK SWWD THROUGH
NRN AND SWRN TX. WARM FRONT WILL EXTEND SEWD FROM THE LOW THROUGH
THE LOWER MS VALLEY AREA AND LIFT NEWD DURING THE DAY...WHILE THE
COLD FRONT CONTINUES SWD THROUGH THE LOWER MS VALLEY INTO CNTRL TX
WHERE IT WILL LIKELY STALL OVERNIGHT.

...LOWER MS VALLEY REGION...

ELEVATED STORMS WILL PROBABLY BE ONGOING WITHIN ZONE OF ISENTROPIC
ASCENT ALONG AND NORTH OF WARM FRONT FROM PORTIONS OF ARK EWD INTO
THE TN VALLEY. SOUTH OF THIS BOUNDARY...PARTIALLY MODIFIED GULF AIR
WITH SFC DEWPOINTS IN THE LOW TO MID 60S WILL HAVE ADVECTED THROUGH
THE PRE-FRONTAL WARM SECTOR. POTENTIAL WILL EXIST FOR THE ATMOSPHERE
TO BECOME MODERATELY UNSTABLE /1000-1500 J/KG MLCAPE/ AS DIABATIC
WARMING OF THE BOUNDARY LAYER COMMENCES. ERN EXTENSION OF THE EML
WILL LIKELY HAVE ADVECTED THROUGH WARM SECTOR RESULTING IN AT LEAST
A MODEST CAP. HOWEVER...THE CAP WILL LIKELY WEAKEN AS THE BOUNDARY
LAYER DESTABILIZES AND STORMS MAY DEVELOP ALONG AND AHEAD OF SEWD
ADVANCING COLD FRONT SATURDAY AFTERNOON. LLJ IS FORECAST TO SHIFT
INTO THE TN VALLEY EARLY IN PERIOD IN ASSOCIATION WITH LEAD VORT MAX
EJECTING THROUGH ERN PERIPHERY OF UPPER TROUGH LEAVING WEAK AND
VEERED LOW LEVEL WINDS IN WARM SECTOR. HOWEVER...BELT OF STRONGER
UPPER FLOW WITHIN BASE OF THE TROUGH WILL CONTRIBUTE TO 40-50 KT
LARGELY UNIDIRECTIONAL 0-6 KM SHEAR. POTENTIAL WILL EXIST FOR SOME
UPDRAFTS TO ROTATE WITH STORM SPLITS ALSO POSSIBLE ALONG WITH AN
ATTENDANT THREAT FOR ISOLATED LARGE HAIL AND DAMAGING WIND GUSTS.

...SWRN THROUGH CNTRL TX...

EML WILL HAVE ADVECTED THROUGH THE MOISTENING WARM SECTOR RESULTING
IN MODERATE INSTABILITY...BUT ALSO A CAP. COLD FRONT WILL SETTLE SWD
TOWARD CNTRL TX DURING THE DAY AS THE UPPER TROUGH ADVANCES EWD.
HOWEVER...FLOW IN THE 0-3 KM LAYER IS FORECAST TO BE VERY WEAK AND
THERE IS CONCERN THAT STORM COVERAGE COULD REMAIN SOMEWHAT LIMITED.
OTHER ISOLATED ACTIVITY COULD ALSO MOVE OFF THE HIGHER TERRAIN OF
MEXICO WITHIN DEEP BUT WEAK ELY UPSLOPE REGIME AND SPREAD INTO A
PORTIONS OF SWRN TX. THE TX WARM SECTOR WILL REMAIN SOUTH OF THE
STRONGER FLOW ALOFT WITH SHEAR PROFILES LARGELY SUPPORTIVE OF
MULTICELLS AND MARGINAL SUPERCELL STRUCTURES. STORMS THAT DO DEVELOP
WILL BE CAPABLE OF PRODUCING ISOLATED DAMAGING WIND AND LARGE HAIL.
WILL MAINTAIN 5% SEVERE COVERAGE THIS OUTLOOK...BUT A PORTION OF
CNTRL AND SCNTRL TX MAY NEED TO BE INCLUDED IN A SLIGHT RISK ONCE
STORM COVERAGE CONCERNS HAVE BEEN MITIGATED.

..DIAL.. 04/26/2013

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