DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 261253
SWODY1
SPC AC 261251

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0751 AM CDT FRI APR 26 2013

VALID 261300Z - 271200Z

...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON THROUGH TONIGHT
ACROSS WRN/SRN OK AND ADJACENT N TX...

...SRN PLAINS AREA THROUGH TONIGHT...
A LOW-AMPLITUDE SHORTWAVE TROUGH OVER NE NM/SE CO WILL PROGRESS EWD
TO NW OK THIS EVENING AND THE OK/AR BORDER BY THE END OF THE PERIOD.
AT THE SURFACE...A REMNANT LEE CYCLONE WILL DEVELOP SEWD FROM SE CO
TO NW TX BY THIS EVENING...AND THE WEAK WAVE WILL CONTINUE EWD ALONG
THE RED RIVER OVERNIGHT. MEANWHILE...LOW-LEVEL MOISTURE RETURN IS
UNDERWAY ACROSS TX...WITH 65-70 F BOUNDARY LAYER DEWPOINTS SPREADING
INLAND ACROSS THE MIDDLE AND UPPER TX COAST. FARTHER NW...MOISTURE
IS MORE LIMITED WITH DEWPOINTS IN THE LOW-MID 40S FROM N TX INTO OK.

SURFACE TEMPERATURES ACROSS MUCH OF CENTRAL/NRN/ERN OK WILL BE SLOW
TO WARM TODAY AS A RESULT OF LINGERING CLOUDS IN THE WAA
REGIME...OWING TO ONGOING ELEVATED CONVECTION. THERE WILL BE A
MARGINAL HAIL RISK WITH THE WAA STORMS THIS MORNING BASED ON THE
MUCAPE NEAR 1500 J/KG AND STEEP LAPSE RATES ABOVE 700 MB PER THE 12Z
FWD AND OUN SOUNDINGS. LATER TODAY...SURFACE HEATING AND STEEPENING
LOW-LEVEL LAPSE RATES ARE EXPECTED ACROSS THE SE TX
PANHANDLE/EXTREME WRN OK INTO NW TX...TO THE IMMEDIATE W-SW OF THE
ELEVATED CONVECTION AND NEAR A SHARPENING DRYLINE. SURFACE
HEATING/MIXING AND ASCENT NEAR THE DRYLINE/LEE CYCLONE SHOULD WEAKEN
THE CAP SUFFICIENTLY TO SUPPORT AT LEAST ISOLATED THUNDERSTORM
DEVELOPMENT BY LATE AFTERNOON. THERE IS SOME CONCERN THAT
RELATIVELY COOL SURFACE TEMPERATURES IN OK AND THE MOIST AXIS BEING
A BIT FARTHER TO THE E ALONG THE I-45 CORRIDOR WILL LIMIT THE
SPATIAL EXTENT OF THE STRONGER BUOYANCY AND THE WINDOW OF
OPPORTUNITY FOR SEVERE STORMS THIS AFTERNOON ACROSS WRN OK.
STILL...ANY STORMS THAT FORM WILL HAVE THE POTENTIAL TO PRODUCE
LARGE HAIL AND ISOLATED DAMAGING GUSTS IN AN ENVIRONMENT WITH
SOMEWHAT STRAIGHT HODOGRAPHS AND REASONABLY LARGE
TEMPERATURE-DEWPOINT SPREADS WHERE BUOYANCY IS STRONGER.

FARTHER E ALONG THE RED RIVER...LOW-LEVEL SHEAR WILL BE STRONGER
THROUGH THE DAY AND LOW-LEVEL MOISTURE WILL INCREASE.
HOWEVER...SURFACE-BASED THUNDERSTORM DEVELOPMENT IS QUITE UNCERTAIN
GIVEN THE RELATIVELY WARM TEMPERATURES NOTED NEAR AND ABOVE 700 MB
ACROSS TX THIS MORNING. THE MORE PROBABLE SCENARIO IS FOR
CONVECTION TO FORM AND/OR MOVE INTO SRN/CENTRAL OK BY EARLY TONIGHT
IN TANDEM WITH THE MIDLEVEL TROUGH AS MOISTENING CONTINUES JUST
ABOVE THE SURFACE. THE STORMS TONIGHT WILL ALSO POSE A RISK FOR
HAIL/DAMAGING WINDS.

..THOMPSON/COHEN.. 04/26/2013

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