DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 151935
SWODY1
SPC AC 151933

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0233 PM CDT WED MAY 15 2013

VALID 152000Z - 161200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF TX AND SRN
OK...

...TX/OK...

REMNANT MID LEVEL CIRCULATION IS CURRENTLY LOCATED OVER WICHITA
COUNTY IN NWRN TX...MOVING SLOWLY ENEWD. OVER THE LAST FEW HOURS
DEEP CONVECTION HAS GRADUALLY INCREASED WITHIN WEAK WARM ADVECTION
ZONE ACROSS OK AND MULTIPLE CLUSTERS OF STORMS ARE EXPECTED TO
SPREAD ACROSS CNTRL/SCNTRL INTO ERN OK INTO THE EVENING HOURS.
GIVEN THIS TREND HAVE INCREASED SEVERE PROBS NORTH OF THE RED RIVER
TO ACCOUNT FOR HAIL/WIND POTENTIAL WITH CONVECTIVE CLUSTERING.

FARTHER SOUTH...HAVE EXTENDED HIGHER SEVERE PROBS TO THE RIO GRANDE
RIVER TO ACCOUNT FOR ISOLATED SUPERCELLS THAT SHOULD EMERGE ALONG
WRN PLUME OF INSTABILITY. CU HAVE RECENTLY DEVELOPED OFF THE HIGHER
TERRAIN OF NRN MEXICO...WEST OF DRT...AND THIS IS INDICATIVE OF
STEEP LAPSE RATE ENVIRONMENT THAT EXISTS WITHIN THE BASE OF THE
TROUGH.

LATEST THINKING IS THUNDERSTORMS WILL DEVELOP WITHIN THE BASE OF THE
TROUGH FROM NWRN TX...SWD ALONG THE DRYLINE BY LATE AFTERNOON. THE
MOST LIKELY AREA FOR CONCENTRATED SEVERE INITIATION IS PRIMARILY
NORTH OF I-20. WITH TIME ONE OR MORE MCS-TYPE STRUCTURES COULD
EVOLVE AS THE OVERALL COMPLEX OF STORMS SPREADS TOWARD THE I-35
CORRIDOR.

..DARROW.. 05/15/2013

.PREV DISCUSSION... /ISSUED 1138 AM CDT WED MAY 15 2013/

CORRECTED FOR WORDING AT THE END OF 2ND PARAGRAPH.

...NRN AND ERN TX/SRN OK...
COMPLEX SRN BRANCH SHORT WAVE DISTURBANCE FROM ERN NM TO W TX WILL
DRIFT/LIFT ENEWD TDY WHILE EVOLVING INTO A CLOSED LOW CENTERED OVER
OK BY THIS EVENING. A MOIST PLUME CHARACTERIZED BY PW VALUES AROUND
1.5 INCHES WITHIN THE ERN QUADRANT OF THIS SYSTEM WILL CONTINUE TO
FUEL SCATTERED TSTMS AMIDST A GRADUALLY DESTABILIZING AIRMASS ACROSS
CNTRL AND NRN TX. BAND OF ASCENT CURRENTLY SUPPORTING POORLY
ORGANIZED STORMS ACROSS ERN TX IS FORECAST TO CONTINUE TO DRIVE
CONVECTION ENEWD ACROSS SERN OK AND THE ARKLATEX TODAY. AIRMASS TO
THE EAST AND NORTHEAST OF THIS CONVECTION IS FORECAST TO REMAIN ONLY
MARGINALLY UNSTABLE GIVEN WIDESPREAD CLOUD COVER/MARGINAL LAPSE
RATES. DEEP SHEAR AND POCKETS OF GREATER POTENTIAL INSTABILITY OVER
THESE AREAS MAY CONTRIBUTE TO A GRADUAL INCREASE IN SEVERE HAIL/WIND
POTENTIAL BUT OVERALL POTENTIAL APPEARS LIMITED.

A GREATER SEVERE WEATHER THREAT SHOULD EVOLVE AS THE UPPER LOW
CONSOLIDATES ACROSS OK LATER TODAY AND A BAND OF STRONGER MID LEVEL
WLY FLOW DEVELOPS SOUTH OF THE LOW CENTER...ACROSS THE RED RIVER
VALLEY AND NORTH TX. THIS SHOULD OCCUR COINCIDENT WITH THE STRONGEST
DIURNAL DESTABILIZATION EAST OF A SHARPENING DRYLINE. WEAKENING
INHIBITION AND MLCAPE OF 1500-2000 J/KG...ALONG WITH JUXTAPOSITION
OF MID AND HIGH-LEVEL WIND MAXIMA AND 30-35KT LLJ...WILL COMBINE TO
SUPPORT THE DEVELOPMENT OF ORGANIZED STORMS INCLUDING SUPERCELLS
CAPABLE OF LARGE HAIL AND A COUPLE OF TORNADOES. ACTIVITY MAY
CONGEAL INTO ONE OR TWO SMALL SEWD MOVING MCS/S THROUGH THE EVENING
WITH WIND DAMAGE AND LARGE HAIL POTENTIAL SPREADING ESEWD OR SEWD
ACROSS THE I-35 CORRIDOR/DFW METROPLEX. THIS SCENARIO IS SUPPORTED
BY HIGH PROBABILITIES FOR ORGANIZED STORMS IN THE 00Z STORM SCALE
GUIDANCE FROM SPC SSEO AND AFWA ENSEMBLE. NOTE...00Z SSEO IS MISSING
4KM WRF-NMM MEMBER.

...S TX...
ROBUST STORM DEVELOPMENT IS ALSO EXPECTED OVER THE SERRANIAS DEL
BURRO RANGE THIS AFTERNOON AIDED BY MOIST LOW-LEVEL UPSLOPE FLOW.
STRONG INSTABILITY AND SHEAR ACROSS THE MIDDLE/LOWER RIO GRANDE
VALLEY WILL CONTRIBUTE TO A SUPERCELL REGIME WITH ACTIVITY MOVING
EWD/SEWD. AN INCREASED RISK FOR LARGE HAIL AND DAMAGING WINDS SHOULD
DEVELOP OVER PARTS OF THE EDWARDS PLATEAU AND BRUSH COUNTRY THROUGH
THE EVENING AND INTO TONIGHT. GIVEN SOMEWHAT STRONGER INHIBITION AND
WEAKER LARGE SCALE ASCENT ACROSS THESE AREAS OF S TX...STORM
COVERAGE MAY REMAIN ISOLATED TO WIDELY SCATTERED.

...PA/NRN WV...
STRONG DEEP-LAYER WLY FLOW TO THE SOUTH OF A FAST MOVING SHORT WAVE
TROUGH OVER CANADA HAS TRANSPORTED A STEEP LAPSE RATE PLUME EAST
FROM THE PLAINS/MIDWEST. WARM SECTOR DESTABILIZATION WILL OCCUR
AMIDST WEAK TO MODEST LARGE SCALE ASCENT AND MORE THAN ADEQUATE
UNIDIRECTIONAL SHEAR AND LAPSE RATES FOR A FEW STRONG TO SEVERE
STORMS. UNCERTAINTY REVOLVES AROUND CONVECTION OVERCOMING STRONG
INHIBITION ASSOCIATED WITH THE EML PLUME/CAPPING AHEAD OF THE COLD
FRONT SETTING INTO THE REGION LATER TONIGHT. SURFACE TEMPS WILL HAVE
TO ATTAIN VALUES WELL INTO THE 80S F TO RESULT IN SFC-BASED STORMS
IN THIS REGIME AND...WHILE A COUPLE OF STORMS SEEM
POSSIBLE...OVERALL SEVERE HAIL/WIND THREAT MAY BE CONFINED TO AREAS
IMMEDIATELY ALONG SRN PA BORDER AND NRN WV PNHDL WITH UNCERTAINTY
INCREASING WITH EWD EXTENT.

...CNTRL PLAINS/MIDWEST...
SURFACE FRONT TRAILING THE STRONG SHORT WAVE IN CANADA HAS SLOWED
AND BECOME ELONGATED FROM WEST TO EAST...FROM THE KS/NEB BORDER
ACROSS NRN MO TO THE UPPER MIDWEST. WHILE MUCH OF THE FRONTAL ZONE
LIES SOUTH OF STRONGER MID LEVEL FLOW...SURFACE HEATING ALONG AND
SOUTH OF THE BOUNDARY AND MARGINAL LOW LEVEL MOISTURE WILL
CONTRIBUTE TO A NARROW CORRIDOR OF MODEST INSTABILITY THROUGH THE
AFTERNOON. SCATTERED RELATIVELY HIGH-BASED STORMS SEEM POSSIBLE IF
CONVECTIVE INHIBITION CAN BE OVERCOME. THIS PROCESS MAY BE ENHANCED
THROUGH DIFFERENTIAL HEATING NEAR THE FRONT...FROM IL EWD TO
OH...AND FARTHER WEST ACROSS MO AND NERN KS...BENEATH WEAK MID LEVEL
DEFORMATION ZONE. GENERALLY WEAK FLOW ACROSS THESE AREAS SHOULD
LIMIT STORM PERSISTENCE/ORGANIZATION AND ONLY A LOW PROBABILITY WIND
THREAT AND PERHAPS SOME HAIL BEING THE EXPECTED THREATS WITH ANY
STORMS THAT CAN INITIATE.

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