DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 271250
SWODY1
SPC AC 271247

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0747 AM CDT FRI SEP 27 2013

VALID 271300Z - 281200Z

...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO TONIGHT
ACROSS PARTS OF THE CNTRL AND SRN PLAINS...

...SYNOPSIS...

A SIGNIFICANT VORTICITY MAXIMUM AND ASSOCIATED MID AND UPPER-LEVEL
JET STREAKS WITHIN THE BASE OF THE PARENT LONG-WAVE TROUGH OVER THE
LOWER CO VALLEY WILL TRANSLATE NEWD INTO THE NRN AND CNTRL HIGH
PLAINS BY 28/12Z. THIS UPPER-AIR SYSTEM WILL BE ATTENDED BY A
MIGRATORY LEE CYCLONE WHICH WILL DEEPEN OVER ERN CO TODAY BEFORE
RAPIDLY DEVELOPING NEWD ALONG A QUASI-STATIONARY BOUNDARY INTO THE
UPPER MS VALLEY BY TONIGHT. A TRAILING COLD FRONT WILL ADVANCE SEWD
THROUGH THE HIGH PLAINS...GRADUALLY OVERTAKING A DRYLINE WHICH WILL
STRETCH FROM THE ERN CO LOW SWD INTO WRN TX DURING THE PEAK OF
AFTERNOON HEATING.

...CNTRL/SRN PLAINS THIS AFTERNOON INTO TONIGHT...

EARLY MORNING SATELLITE-DERIVED PW IMAGERY INDICATES THE NWD FLUX OF
AN INCREASINGLY MOIST AIR MASS INTO CNTRL TX FROM THE NWRN GULF OF
MEXICO WITHIN THE SRN EXTENSION OF THE NOCTURNAL LOW-LEVEL WIND
MAXIMUM. A DYNAMICALLY FORCED SLY LLJ WILL MAINTAIN THIS PROCESS
TODAY WITH DEWPOINTS RISING INTO THE 60S EAST OF THE DRYLINE AS FAR
NORTH AS THE TX/OK PNHDLS AND PERHAPS PARTS OF WRN KS. AND WHILE
MIDLEVEL LAPSE RATES WILL NOT BE PARTICULARLY STEEP...THIS MOISTURE
INCREASE ALONG WITH DAYTIME HEATING WILL SUPPORT THE DIURNAL
DESTABILIZATION OF THE WARM SECTOR WITH AFTERNOON MLCAPE VALUES
RANGING FROM 500-750 J/KG OVER SWRN NEB/NWRN KS TO 1000-1250 J/KG
ACROSS THE ERN TX PNHDL.

SCATTERED STORM DEVELOPMENT IS ANTICIPATED BY MID TO LATE AFTERNOON
AS LOW-LEVEL CONVERGENCE FROM THE SURFACE TRIPLE POINT SWD ALONG THE
DRYLINE IS AUGMENTED BY INCREASING HEIGHT FALLS/DCVA DOWNSTREAM FROM
THE MIDLEVEL TROUGH. THE STORM INITIATION WILL BE COINCIDENT WITH A
NOTABLE STRENGTHENING OF THE DEEP-LAYER WIND FIELD AND RESULTANT
VERTICAL SHEAR WITH A MIXTURE OF SUPERCELLS AND BOWING STRUCTURES
POSSIBLE.

LARGE HAIL POTENTIAL IS EXPECTED TO BE LIMITED BY THE MARGINALLY
STEEP MIDLEVEL LAPSE RATES WITH THE HIGHEST PROBABILITY OF
OCCURRENCE BEING ACROSS SRN PORTIONS OF THE SLIGHT RISK AREA WHERE A
MORE MOIST BOUNDARY LAYER WILL CONTRIBUTE TO STRONGER INSTABILITY.
OTHERWISE...INITIALLY SIZABLE T-TD SPREADS /ESPECIALLY ACROSS KS AND
NEB/ WILL LIKELY PROMOTE COLD POOL GENERATION AND AN INCREASING RISK
FOR DAMAGING WINDS. TORNADO POTENTIAL MAY INCREASE BY EARLY EVENING
WITH ANY STORMS THAT CAN REMAIN MORE DISCRETE OWING TO THE CONTINUED
STRENGTHENING OF LOW-LEVEL SHEAR AND GRADUALLY LOWERING LCL
HEIGHTS.

BY LATE EVENING INTO TONIGHT...STORMS ARE EXPECTED TO GROW UPSCALE
INTO A BROKEN QLCS ALONG THE SURGING COLD FRONT WITH AN ISOLATED
DAMAGING WIND THREAT PERSISTING UNTIL ABOUT 28/06Z FROM CNTRL NEB
INTO WRN OK/NWRN TX.

..MEAD/MOSIER.. 09/27/2013

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