DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 171240
SWODY1
SPC AC 171238

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0738 AM CDT WED APR 17 2013

VALID 171300Z - 181200Z

...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON AND EVENING OVER
MUCH OF OK...SOUTHEAST KS...WESTERN NORTH TX...AND FAR WESTERN MO...

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE SOUTHERN PLAINS INTO
THE MID MS VALLEY...

...FOCUSED AREA OF SIGNIFICANT SEVERE THUNDERSTORM AND TORNADO
POTENTIAL IS EXPECTED TODAY...

...OK/WESTERN NORTH TX/SOUTHEAST KS...
THE MORNING SURFACE ANALYSIS SHOWS A WARM FRONT EXTENDING FROM
SOUTHWEST TO NORTHEAST OK. THIS BOUNDARY IS RAPIDLY RETREATING
NORTHWARD AND IS EXPECTED TO LIE ROUGHLY FROM WEST-CENTRAL OK INTO
SOUTHEAST KS BY MID AFTERNOON. RICH LOW LEVEL MOISTURE SOUTH OF THE
BOUNDARY WILL COMBINE WITH AMPLE DAYTIME HEATING TO YIELD AFTERNOON
MLCAPE VALUES OF 3000+ J/KG OVER MOST OF THE SOUTHEAST HALF OF OK
AND SOUTHEAST KS.

VARIOUS MODEL SOLUTIONS CONTINUE TO STRUGGLE WITH SHORT-TERM DETAILS
OF CONVECTIVE POTENTIAL. THIS APPEARS TO BE DUE TO HANDLING OF
SUBTROPICAL SHORTWAVE SEEN IN WATER VAPOR IMAGERY OVER SOUTHERN NM.
LARGE SCALE FORCING FOR ASCENT WILL OVERSPREAD OK THROUGHOUT THE DAY
IN ADVANCE OF THIS SYSTEM...BUT IT APPEARS THAT 700MB TEMPERATURES
APPROACHING 10C WILL SUPPRESS SIGNIFICANT CONVECTION OVER
WESTERN/CENTRAL OK UNTIL THIS AFTERNOON WHEN PERSISTENT LIFT AND
STRONG HEATING WILL WEAKEN THE CAP IN VICINITY OF THE DRYLINE.

PRESENT INDICATIONS ARE THAT ISOLATED THUNDERSTORMS WILL DEVELOP BY
LATE AFTERNOON ALONG THE DRYLINE IN SOUTHWEST OK AND WESTERN NORTH
TX...AND ALONG THE STALLED BOUNDARY EXTENDING ACROSS NORTH CENTRAL
OK INTO SOUTHEAST KS. VERTICAL SHEAR PROFILES WILL BE QUITE STRONG
THROUGHOUT THIS AREA WITH 0-3KM SRH VALUES EXCEEDING 300 M2/S2 AND
STRONG EFFECTIVE SHEAR. DISCRETE SUPERCELL STORMS ARE EXPECTED WITH
A RESULTANT RISK OF VERY LARGE HAIL AND A FEW STRONG TORNADOES.
THESE STORMS ARE EXPECTED TO TRACK NORTHEASTWARD ALONG AND SOUTH OF
THE SURFACE BOUNDARY INTO NORTHEAST OK AND EVENTUALLY WESTERN MO
THIS EVENING.

...MO/IL...
STRENGTHENING SOUTHERLY LOW LEVEL WINDS ARE FORECAST ACROSS MUCH OF
MO/IL TODAY...WITH MODERATE CAPE VALUES ALREADY IN PLACE. OTHER
THAN LOW LEVEL WARM ADVECTION...LARGE SCALE FORCING MECHANISMS ARE
SUBTLE. NEVERTHELESS...STEEP MID LEVEL LAPSE RATES AND SUFFICIENT
EFFECTIVE SHEAR WILL POSE A CONDITIONAL RISK OF HAIL IN THOSE STORMS
THAT CAN DEVELOP TODAY.

...MO/KS/OK/NORTH TX OVERNIGHT...
THE MAIN UPPER TROUGH IS EXPECTED TO SWING EASTWARD INTO THE PLAINS
LATE TONIGHT...RESULTING IN A LARGE SQUALL LINE AFFECTING EASTERN
KS...CENTRAL/EASTERN OK...WESTERN MO...AND NORTH TX. IT APPEARS
LIKELY THAT THESE STORMS WILL POSE A RISK OF RATHER WIDESPREAD
DAMAGING WINDS THROUGH 12Z.

...TN VALLEY TO CENTRAL/SOUTHERN APPALACHIANS...
AT LEAST ISOLATED TO WIDELY SCATTERED TSTMS ARE EXPECTED TO
DIURNALLY INCREASE THIS AFTERNOON ACROSS THE REGION. WHILE FORCING
ON THE LARGE SCALE WILL BE MODEST AND MID-LEVEL LAPSE RATES/
VERTICAL SHEAR WILL BE WEAK...STEEPENING LOW LEVEL LAPSE RATES
DURING THE AFTERNOON MAY CONTRIBUTE TO SOME POTENTIAL FOR EPISODIC
BOUTS OF LOCALLY DAMAGING WINDS/HAIL.

..HART/GARNER.. 04/17/2013

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.