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000
ACUS01 KWNS 241930
SWODY1
SPC AC 241928

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0228 PM CDT FRI MAY 24 2013

VALID 242000Z - 251200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE NORTHERN AND CENTRAL
HIGH PLAINS...

EARLIER THOUGHTS REGARDING THE CONVECTIVE EVOLUTION OF HIGH PLAINS
SEVERE EVENT REMAIN.  FOR THIS REASON HAVE MADE ONLY MINOR
ADJUSTMENTS TO 1630Z PRODUCT.

DESPITE THE RELATIVELY WEAK DEEP LAYER SHEAR OBSERVED ACROSS
PORTIONS OF NWRN TX AND WRN OK...INSTABILITY HAS INCREASED MARKEDLY
ACROSS THIS REGION.  SBCAPE IS NOW IN EXCESS OF 3000 J/KG ACROSS
THIS REGION AND WITH MINIMAL INHIBITION IT APPEARS SCT TSTMS WILL
DEVELOP ACROSS THIS AREA OVER THE NEXT FEW HOURS.  HAIL/WIND MAY
ACCOMPANY THE STRONGEST STORMS BUT OVERALL SEVERE COVERAGE SHOULD
REMAIN SPARSE...THUS ONLY 5 PERCENT SEVERE FOR THIS REGION.

..DARROW.. 05/24/2013

.PREV DISCUSSION... /ISSUED 1125 AM CDT FRI MAY 24 2013/

...SYNOPSIS...

A PROMINENT MID TO UPPER-LEVEL LOW WILL BE MAINTAINED THROUGH THE D1
PERIOD OVER THE PACIFIC NW AND SRN BC/AB...RESULTING IN A SWLY FLOW
REGIME ACROSS THE INTERMOUNTAIN WEST INTO NRN/CNTRL PLAINS.  AN
EMBEDDED VORTICITY MAXIMUM OVER THE NRN HIGH PLAINS WILL PIVOT NEWD
TODAY WHILE A SERIES OF WEAKER PERTURBATIONS TRANSLATE THROUGH THE
GREAT BASIN INTO NRN/CNTRL HIGH PLAINS.  DOWNSTREAM FROM THESE
DEVELOPMENTS...THE SRN PORTION OF AN AMPLIFIED MIDLEVEL TROUGH FROM
ERN CANADA INTO THE CNTRL/SRN APPALACHIANS WILL PROGRESS EWD/NEWD TO
OFF THE MID-ATLANTIC COAST BY SATURDAY MORNING.

IN THE LOW LEVELS...THE PREVAILING SWLY MIDLEVEL FLOW REGIME ACROSS
THE ROCKIES WILL MAINTAIN A LEE LOW OVER THE CNTRL HIGH PLAINS WITH
A LEE TROUGH/DRYLINE EXTENDING SWD INTO SWRN TX.

...CNTRL/SRN HIGH PLAINS THIS AFTERNOON AND EVENING...

THE LARGE-SCALE PATTERN WILL SUSTAIN A SLY LLJ ACROSS THE NRN/CNTRL
PLAINS TODAY WHICH WILL ENHANCE THE NWD FLUX OF AN INCREASINGLY
MOIST PBL CHARACTERIZED BY DEWPOINTS IN THE UPPER 50S TO LOWER 60S.
THIS PROCESS WILL OCCUR BENEATH AN EML WHERE 700-500-MB LAPSE RATES
OF 8.0-9.5 C/KM WERE OBSERVED BY 12Z REGIONAL RAOBS.  WHEN COUPLED
WITH DAYTIME HEATING...THE ENVIRONMENT IS EXPECTED TO BECOME
MODERATELY UNSTABLE BY AFTERNOON WITH MLCAPE VALUES APPROACHING
1000-2000 J/KG.

LATEST MODEL GUIDANCE SUGGESTS THAT LARGE-SCALE FORCING FOR ASCENT
WILL REMAIN NEGLIGIBLE THROUGH THE PEAK OF THE DIURNAL HEATING CYCLE
WITH LITTLE CHANGE TO THE 500-MB HEIGHT FIELD.  THERE IS SOME
INDICATION IN CURRENT WATER VAPOR IMAGERY THAT A WEAK PERTURBATION
MAY BE MOVING INTO THE FOUR CORNERS REGION...WHICH MAY APPROACH THE
DISCUSSION AREA THIS EVENING.  IN GENERAL...IT APPEARS THAT STRONG
HEATING ALONG THE DRYLINE/LEE TROUGH --AND PERHAPS SOME WEAK UPSLOPE
COMPONENT-- WILL BE THE PRIMARY MECHANISM/S/ INITIATING ISOLATED
STORMS LATER THIS EVENING.

FORECAST HODOGRAPHS VALID 25/00Z EXHIBIT 20-30 KT SSELY LOW-LEVEL
WINDS VEERING TO WLY AT 25-30 KT IN THE MIDLEVELS WHICH WILL BE
SUPPORTIVE OF SUPERCELL DEVELOPMENT GIVEN THE MODERATE INSTABILITY.
WHILE LARGE HAIL WILL BE THE PRIMARY HAZARD...A TORNADO OR TWO IS
POSSIBLE...AS ARE LOCALLY DAMAGING WIND GUSTS.  STORMS MAY CONGEAL
INTO CLUSTERS LATER THIS EVENING BEFORE WEAKENING TONIGHT AS THE PBL
COOLS AND STABILIZES.

...SRN TX THIS AFTERNOON AND EVENING...

A NOCTURNAL MCS HAS GENERATED A WELL-DEFINED MCV /PER RADAR DATA/
OVER THE EDWARDS PLATEAU WHICH SHOULD SLOWLY DRIFT EWD/SEWD TODAY.
FORCING ASSOCIATED WITH THIS FEATURE AND LOW-LEVEL UPLIFT ALONG
RESIDUAL OUTFLOW BOUNDARIES WILL PROMOTE AN INCREASE IN STORMS THIS
AFTERNOON ACROSS THE EDWARDS PLATEAU AND HILL COUNTRY INTO THE BRUSH
COUNTRY.  WHILE VERTICAL SHEAR WILL REMAIN WEAK...THE PRESENCE OF A
MOIST AND MODERATELY UNSTABLE ENVIRONMENT WILL BE SUPPORTIVE OF
VIGOROUS STORMS WITH A RISK FOR LOCALLY DAMAGING WINDS OWING TO
WATER-LOADED DOWNDRAFTS.