DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 261720
SWODY2
SPC AC 261718

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1218 PM CDT WED SEP 26 2012

VALID 271200Z - 281200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
IN MID-UPPER LEVELS...GENERALLY LOOSE HEIGHT GRADIENTS ARE FCST OVER
MOST OF CONUS THROUGH PERIOD...EXCEPT FOR BELT OF CYCLONIC FLOW OVER
GREAT LAKES. EMBEDDED SHORTWAVE TROUGH -- NOW ANALYZED OVER UPPER
GREAT LAKES AND MI -- IS FCST TO PIVOT EWD ACROSS LOWER GREAT LAKES
AND ST. LAWRENCE VALLEY THROUGH REMAINDER DAY-1 AND BECOME ABSORBED
INTO MUCH STRONGER TROUGH OVER ERN QUE/LABRADOR. PRONOUNCED
SHORTWAVE TROUGH -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY OVER FAR
NERN SK/NWRN AB AND SRN NUNAVUT -- IS FCST TO TURN SEWD ACROSS SRN
HUDSON BAY REGION AND NRN ONT DAY-2. THIS PERTURBATION WILL
CONTRIBUTE HEIGHT FALLS AND ENHANCED WINDS ALOFT OVER UPPER GREAT
LAKES REGION AFTER ABOUT 28/00Z. NRN-STREAM SHORTWAVE TROUGH AND
EMBEDDED VORTICITY MAX -- NOW EVIDENT INVOF MT/AB/SK BORDER JUNCTION
-- SHOULD MOVE SLOWLY ESEWD DAY-1. AS RIDGE BUILDS TO ITS N...THIS
TROUGH MAY BECOME TEMPORARILY CUT OFF FROM NRN STREAM
DAY-2...MEANDERING ERRATICALLY ABOUT ERN MT/WRN ND REGION BEFORE
BEING ENTRAINED INTO PREVAILING WLYS AGAIN DAY-3. WEAK MID-UPPER
LEVEL LOW...NOW QUASISTATIONARY OVER CO/UT BORDER -- IS EXPECTED TO
MOVE EWD ACROSS CENTRAL ROCKIES TO CENTRAL HIGH PLAINS DAY-2...WHILE
FURTHER DEVOLVING INTO OPEN-WAVE TROUGH.

AT SFC...COLD FRONT WAS ANALYZED FROM SRN ONT SWWD ACROSS NRN
INDIANA...CENTRAL IL...WRN MO...SERN KS...NWRN OK AND ERN NM.
FRONTAL ZONE SHOULD MOVE OFF NEW ENGLAND COAST EARLY IN
PERIOD...WHILE MOVING SWD AND DECELERATING OVER MID-ATLC/CENTRAL
APPALACHIANS REGION. SEGMENT OF FRONT W OF MS RIVER SHOULD BECOME
QUASISTATIONARY...EXCEPT WHERE PERTURBED ON MESOSCALE BY SMALL
MIDLEVEL WAVES AND CONVECTIVE PROCESSES. BY 28/00Z...ERN FRONTAL
SEGMENT SHOULD EXTEND FROM DELMARVA PENINSULA...NRN VA...WV...AND
KY...WITH WEAK FRONTAL-WAVE LOW POSSIBLE OVER NRN VA.

...CENTRAL/SRN HIGH PLAINS TO VA...
SCATTERED MULTICELLULAR TSTMS MAY DEVELOP INVOF FRONTAL ZONE --
PRIMARY DURING AFTERNOON INTO EARLY EVENING FROM VA TO CENTRAL/SRN
HIGH PLAINS -- WITH AT LEAST ISOLATED/MRGL SVR POTENTIAL. NODES OF
RELATIVELY CONCENTRATED SVR RISK WITHIN THIS CORRIDOR WILL BE VERY
CONDITIONAL/DEPENDENT UPON GAPS BETWEEN SWATHS OF CLOUDS/PRECIP...AS
WELL AS MESOSCALE BOUNDARIES...LEFT BEHIND FROM DAY-1 AND
MORNING/DAY-2 ACTIVITY. THIS CORRIDOR WILL LIE S OF STRONGEST
MIDLEVEL FLOW AND IN ZONE OF GENERALLY WEAK LOW-LEVEL
WINDS...ALTHOUGH 70-80 KT OF CONVECTIVELY VENTILATING/ANVIL-LEVEL
FLOW IS POSSIBLE ACROSS ERN NM...TX PANHANDLE...OK AND SRN KS.
BACKED SFC FLOW N OF FRONT ALSO MAY ENHANCED DEEP-LAYER SHEAR IN
SUPPORT OF TSTM ORGANIZATION...ESPECIALLY FROM LOWER OH VALLEY
ACROSS OZARKS TO S-CENTRAL PLAINS. 60S F SFC DEW POINTS WILL BE
COMMON OVER CORRIDOR E OF HIGH PLAINS...SUPPORTING 1000-2000 J/KG
MID-LATE AFTERNOON MLCAPE IN AREAS OF PERSISTENT/SUSTAINED
INSOLATION.

..EDWARDS.. 09/26/2012

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