DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 041951
SWODY1
SPC AC 041949

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0249 PM CDT TUE JUN 04 2013

VALID 042000Z - 051200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE CENTRAL/SRN
PLAINS...

THE ONLY APPRECIABLE CHANGE THIS FORECAST UPDATE IS TO ADD WIND
PROBABILITIES FOR PARTS OF THE GA/SC COASTAL PLAIN. TEMPS HAVE
WARMED TO NEAR 90 DEG AWAY FROM THE COAST AND SCTD STORMS HAVE
DEVELOPED OVER THE PAST FEW HOURS. WEAK DEEP SHEAR AND MODERATE
SURFACE-BASED INSTABILITY /SBCAPE AOA 1500 J/KG PER OBJECTIVE
ANALYSIS/ HAS LED TO STRONG UPDRAFTS EXHIBITING MOSTLY A PULSE-LIKE
CHARACTER. AS A RESULT...A FEW LOCALIZED POCKETS OF WIND DAMAGE ARE
POSSIBLE WITH THE STRONGEST CORES OVER THE NEXT SEVERAL HOURS BEFORE
CONVECTIVE OVERTURNING AND THE LOSS OF DAYTIME HEATING ACT TO WEAKEN
THIS ACTIVITY BY THE EARLY EVENING.

ELSEWHERE...THE FORECAST IS ON TRACK.

..SMITH.. 06/04/2013

.PREV DISCUSSION... /ISSUED 1128 AM CDT TUE JUN 04 2013/

...CENTRAL/SRN PLAINS...
MODERATE WLY MID LEVEL WINDS ARE FORECAST TO CONTINUE FROM THE
CENTRAL ROCKIES EWD ACROSS THE CENTRAL PLAINS...TO THE SOUTH OF A
SLOW MOVING UPPER LOW APPROACHING THE UPPER MS VALLEY. SUBTLE
PERTURBATIONS IN THE FLOW MAY MODULATE CONVECTIVE POTENTIAL BUT
DYNAMIC FORCING FOR LARGE SCALE ASCENT APPEARS LIMITED OVER MOST OF
THE RISK AREA. AT THE SURFACE...A COLD FRONT FROM ERN NEB SWWD INTO
SERN CO WILL CONTINUE SLOWLY SWD...WITH ELY UPSLOPE WINDS DEVELOPING
THIS AFTERNOON TO THE NORTH OF THE FRONT IN ERN CO. TO THE SOUTH OF
THE FRONT...A BROAD SURFACE LOW IS FORMING OVER WEST TX WHILE A N/S
DRY LINE IS EXPECTED TO BECOME BETTER ESTABLISHED FROM EXTREME SERN
CO INTO THE CENTRAL TX PANHANDLE AND SWD AS HEATING/MIXING OCCURS
INTO THE AFTERNOON.

THE EARLY MORNING MCS HAS WEAKENED CONSIDERABLY AS IT MOVED INTO
SERN OK WITH AN OUTFLOW BOUNDARY EXTENDING ACROSS NRN TX. CLOUDS
HAVE DIMINISHED RAPIDLY OVER WRN/CENTRAL OK IN THE WAKE OF THE
MCS...AND THIS IS RESULTING IN AN AXIS OF STRONG DIABATIC HEATING
FROM NWRN TX INTO SWRN KS AND SERN CO. 12Z RAOBS OVER THE HIGH
PLAINS EXHIBITED STEEP MID LEVEL LAPSE RATES...AND WITH SURFACE DEW
POINTS IN THE 50S TO MID 60S EAST OF THE DRY LINE THE ENVIRONMENT
WILL BECOME MODERATELY UNSTABLE FROM SWRN KS INTO WRN OK AND NWRN TX
WITH MLCAPE OF 1500-2500 J/KG. CONTINUED HEATING AND LOW LEVEL
CONVERGENCE NEAR THE FRONT AND DRY LINE WILL GRADUALLY ERODE THE CAP
WITH WIDELY SCATTERED STORMS DEVELOPING BY LATE AFTERNOON. VEERING
WIND WITH HEIGHT AND 35-45 KT DEEP LAYER SHEAR WILL PROMOTE
ORGANIZED CONVECTIVE STRUCTURES INCLUDING A FEW SUPERCELLS.
STRONGEST STORMS WILL BE CAPABLE OF PRODUCING VERY LARGE HAIL FROM
SWRN KS INTO WRN OK ALONG WITH DAMAGING WIND GUSTS AND POSSIBLY A
TORNADO OR TWO.

ADDITIONAL STORMS ARE EXPECTED TO FORM OVER PARTS OF ERN CO AMIDST A
MOIST UPSLOPE LOW LEVEL WIND ENVIRONMENT. MODEL GUIDANCE CONTINUES
TO SUGGEST THAT STORMS IN CO MAY EVENTUALLY GROW UPSCALE INTO AN
ESEWD MOVING MCS TONIGHT MOVING INTO KS AND OK AS CONVERGENCE
INCREASES ON THE NOSE OF AN INTENSIFYING LOW LEVEL JET OVER THE SRN
HIGH PLAINS. IF THIS SCENARIO OCCURS... POTENTIAL WILL EXIST FOR A
MORE ORGANIZED WIND DAMAGE THREAT ALONG THE LEADING EDGE OF THE MCS
AS IT CONTINUES INTO THE OVERNIGHT HOURS.

FARTHER NORTHEAST OVER PARTS OF ERN KS/SERN NEB/SWRN IA AND EXTREME
NWRN MO...STORMS MAY REDEVELOP ALONG/AHEAD OF THE COLD FRONT.
ALTHOUGH CONSIDERABLE CLOUD COVER AND CONVECTION IS EXPECTED TO
INHIBIT OVERALL DIURNAL HEATING...VISIBLE IMAGERY SHOWS SOME BREAKS
IN CLOUDS WHICH MAY ALLOW POCKETS OF STRONGER DESTABILIZATION TO
OCCUR. EFFECTIVE BULK SHEAR OF 30-40 KT WILL ENHANCE STORM
INTENSITY WITH A FEW STORMS CAPABLE OF PRODUCING MARGINALLY SEVERE
HAIL AND STRONG WINDS.

...ERN DAKOTAS/WRN MN...
AS THE UPPER LOW AND ASSOCIATED/WEAKENING SURFACE LOW SHIFT SLOWLY
EWD ACROSS THE DAKOTAS...THE OCCLUDED FRONT FORECAST TO LIE N-S
ACROSS THE ERN DAKOTAS DURING THE AFTERNOON SHOULD BECOME A FOCUS
FOR DEVELOPMENT OF SHOWERS AND SCATTERED/LOW-TOPPED THUNDERSTORMS.

THOUGH THE LOW-LEVEL FLOW SHOULD REMAIN RELATIVELY WEAK AS THE LOW
FILLS...DEEP-LAYER VEERING/SHEAR COMBINED WITH STEEP MID-LEVEL LAPSE
RATES /OWING TO THE PRESENCE OF THE UPPER LOW/ SUGGEST A THREAT FOR
SEVERAL STRONG/POSSIBLY SEVERE CELLS. LOCALLY GUSTY/DAMAGING
WINDS...MARGINAL HAIL...AND POSSIBLY AN ISOLATED TORNADO WILL BE
POSSIBLE UNTIL CONVECTION WEAKENS THROUGH SUNSET.

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