DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 161936
SWODY1
SPC AC 161934

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0234 PM CDT SUN SEP 16 2012

VALID 162000Z - 171200Z

...NO SVR TSTM AREAS FORECAST...

NO CHANGES WERE REQUIRED TO THE PREVIOUS OUTLOOK.

..JEWELL.. 09/16/2012

.PREV DISCUSSION... /ISSUED 1112 AM CDT SUN SEP 16 2012/

...NRN PLAINS/UPPER MS VALLEY...
UPPER SHORT WAVE TROUGH MOVING ACROSS SRN PARTS OF ALBERTA AND
SASKATCHEWAN IS EXPECTED TO DEEPEN SEWD TOWARD THE NRN PLAINS IN
RESPONSE TO AMPLIFICATION OF AN UPSTREAM RIDGE INTO AK. AT THE
SURFACE...A COLD FRONT CURRENTLY EXTENDING FROM WRN LAKE SUPERIOR
SWWD INTO SRN SD AND NRN WY WILL SIMILARLY MOVE SEWD...REACHING A
LINE FROM NRN LOWER MI/CENTRAL IA INTO NWRN KS AND CO BY THE END OF
THE PERIOD.

A NARROW AXIS OF LOW LEVEL MOISTURE IS EVIDENT IN SURFACE DATA
EXTENDING FROM OK AND ERN KS INTO THE MIDDLE MO VALLEY WHERE SURFACE
DEW POINTS ARE IN THE UPPER 50S-LOWER 60S. MOISTURE MAY SPREAD NEWD
INTO PARTS OF SRN MN/NRN IA IN ADVANCE OF THE APPROACHING COLD FRONT
BUT OVERALL AIR MASS MOISTURE CONTENT IN THIS REGION IS EXPECTED TO
REMAIN MODEST WITH PW AOB 1.0 IN. HOWEVER...A PLUME OF STEEP
MID-LEVEL LAPSE RATES EXTENDS EWD FROM CO/WY ACROSS THE MIDDLE MO
VALLEY...AND WITH LOW-LEVEL LAPSE RATES LIKELY INCREASING THIS
AFTERNOON AS STRONG DIABATIC HEATING OCCURS AHEAD OF THE FRONT FROM
THE CENTRAL PLAINS INTO THE MS VALLEY...DESTABILIZATION WILL OCCUR
WITH MLCAPE REACHING 500-1000 J/KG.

THE VAST MAJORITY OF GUIDANCE FROM DETERMINISTIC MODELS AND THE SREF
INDICATE ELEVATED CONVECTION WILL DEVELOP THIS EVENING AND CONTINUE
TONIGHT BEHIND THE COLD FRONT FROM PARTS OF SD INTO MN AND WI...AS A
WARM LAYER ABOVE 850 MB INHIBITS SURFACE-BASED CONVECTION
INITIATION. A FEW SREF WRF MEMBERS ALSO GENERATE A LOW PROBABILITY
OF CONVECTION FORMING NEAR THE SURFACE FRONT BUT THE BULK OF
CONVECTIVE DEVELOPMENT IS EXPECTED TO OCCUR WELL BEHIND THE FRONT.
THIS SHOULD LIMIT THE THREAT FOR STRONGER CONVECTIVE WIND GUSTS TO
REACH THE SURFACE AND THE 5 PERCENT SEVERE WIND PROBABILITY OVER THE
SRN MN/NRN IA AREA HAS BEEN DISCONTINUED.

ELSEWHERE...SCATTERED THUNDERSTORMS WILL BE POSSIBLE FROM SOUTH TX
INTO MUCH OF THE SOUTHEAST AND LOWER MS VALLEY. WEAK INSTABILITY/
SHEAR SHOULD PRECLUDE A RISK OF ORGANIZED SEVERE STORMS.

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