DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 112002
SWODY1
SPC AC 112000

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0300 PM CDT SUN AUG 11 2013

VALID 112000Z - 121200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE CENTRAL
PLAINS...

...NEB/NERN CO...N CNTRL KS...
VISIBLE IMAGERY SHOWS TOWERING CU ACROSS ERN CO...AS WELL AS INTO
SWRN NEB WHERE TEMPERATURES HAVE REACHED THE MID 80S F. WITH
CONTINUED HEATING...A FEW CLUSTERS OF CELLS SHOULD FORM WITH A LARGE
HAIL AND DAMAGING WIND THREAT AS THEY EVENTUALLY MERGE AND PROPAGATE
IN A SEWD DIRECTION. FOR MORE INFORMATION SEE UPCOMING MESOSCALE
DISCUSSION 1695.

...SRN VA INTO NRN NC...
LAPSE RATE PROFILES ARE GENERALLY POOR BUT AMPLE INSTABILITY EXISTS
FOR A FEW STRONG STORMS. STRONGER FLOW ALOFT/SHEAR OVER VA MAY ALLOW
FOR A CORE OR TWO TO PRODUCE SMALL...MARGINALLY SEVERE HAIL. FOR
MORE INFORMATION SEE MESOSCALE DISCUSSION 1694.

..JEWELL.. 08/11/2013

.PREV DISCUSSION... /ISSUED 1124 AM CDT SUN AUG 11 2013/

...CENTRAL PLAINS INTO WRN IA...
WATER VAPOR IMAGERY SUGGESTS A WEAK SHORT WAVE TROUGH FROM SRN WY
INTO CENTRAL CO IS MOVING ENEWD TOWARD THE PLAINS...AND THIS FEATURE
MAY ENHANCE THUNDERSTORM DEVELOPMENT THIS AFTERNOON AND EVENING.
12Z UPPER AIR DATA AT LBF AND RAP SAMPLED THE EWD EXTENSION OF A
STEEP LAPSE RATE PLUME/EML IN THE 800-550 MB LAYER EMANATING FROM
THE HIGHER TERRAIN TO THE WEST...AND THIS IS EXPECTED TO SPREAD EWD
ACROSS PARTS OF KS/NEB/SRN SD THIS AFTERNOON. SUFFICIENT LOW LEVEL
MOISTURE IS PRESENT WITH SURFACE DEW POINTS IN THE LOW-MID 60S...AND
AS DIABATIC HEATING OCCURS DESTABILIZATION IS EXPECTED INTO THE
AFTERNOON WITH MAXIMUM MLCAPE REACHING 2000-2500 J/KG.

A WEAK FRONTAL BOUNDARY IS ANALYZED FROM NRN IA INTO CENTRAL
NEB...AND THIS MAY PROVIDE A FOCUS FOR WIDELY SCATTERED STORM
DEVELOPMENT BY LATE AFTERNOON AS THE CAP WEAKENS. ADDITIONAL STORMS
MAY DEVELOP FROM PARTS OF ERN WY/NERN CO INTO THE ADJACENT PARTS OF
NEB AND NWRN KS IN ADVANCE OF THE WY/CO SHORT WAVE TROUGH WITHIN A
WEAK LOW LEVEL UPSLOPE FLOW REGIME. ALTHOUGH WINDS ALOFT WILL BE
MODEST AT BEST /20-25 KT AT 500 MB/...VEERING PROFILES AND 25-35 KT
OF EFFECTIVE SHEAR WILL BE SUPPORTIVE OF ORGANIZED MULTICELL AND
POSSIBLY A FEW SUPERCELL STORM STRUCTURES. STRONGER STORMS WILL BE
CAPABLE OF PRODUCING LARGE HAIL AND DAMAGING WIND GUSTS DURING THE
LATE AFTERNOON AND EVENING.

...VA/NC...
THE SRN EDGE OF STRONGER WESTERLY FLOW ALOFT EXTENDS ACROSS SRN
VA/FAR NRN NC WHERE 25-30 KT MID LEVEL WINDS ARE INDICATED BY 12Z
RAOBS AND LATEST VAD PROFILES. STRONG HEATING IS OCCURRING ACROSS
NC ATTM...AND AS CLOUD COVER DIMINISHES OVER PARTS OF CENTRAL/SRN VA
THIS AFTERNOON...POCKETS OF ENHANCED HEATING/DESTABILIZATION WILL
OCCUR AS WELL. DESPITE SURFACE DEW POINTS REMAINING IN THE LOW/MID
70S...WEAK LOW-MID LEVEL LAPSE RATES /GENERALLY LESS THAN 6C PER KM/
WILL TEMPER OVERALL INSTABILITY WITH MAXIMUM MLCAPE OF 1000-1500
J/KG EXPECTED. A FEW STRONGER STORMS ARE EXPECTED TO DEVELOP THIS
AFTERNOON/EVENING AND SPREAD EWD ACROSS THE AREA WITH POTENTIAL TO
PRODUCE ISOLATED STRONG/SEVERE WIND GUSTS.

...TN VALLEY INTO THE APPALACHIANS...
A SMALL MCS IS MOVING EWD ACROSS THE MID-SOUTH AND THIS MAY SPREAD
EWD IN ASSOCIATION WITH A WEAK SHORT WAVE TROUGH MOVING ACROSS THE
REGION. BASED ON THE 12Z BNA RAOB...THE DOWNSTREAM ENVIRONMENT IS
EXPECTED TO CONTINUE TO DESTABILIZE THIS AFTERNOON WITH MLCAPE OF
2000-2500 J/KG. MINIMAL VERTICAL SHEAR IN THE CLOUD-BEARING LAYER
FAVORS DEVELOPMENT OF WEAKLY ORGANIZED MULTICELL AND PULSE STORM
TYPES WITH POTENTIAL FOR ISOLATED WET MICROBURSTS WITH STRONGER
CELLS INTO THIS EVENING.

...INTERIOR OREGON/WA TO NRN ID AND WRN MT...
THE PERSISTENT CLOSED LOW OVER THE OREGON COAST WILL MOVE SLOWLY NWD
OVER WA THROUGH TONIGHT...WHILE SLOWLY EVOLVING INTO MORE OF AN OPEN
WAVE IN RESPONSE TO HEIGHT FALLS OVER THE GULF OF AK. A BELT OF
ENHANCED LOW-MID LEVEL MOISTURE WILL REMAIN FROM WA EWD OVER NRN
ID/WRN MT ON THE N EDGE OF THE MID LEVEL DRY SLOT...WHERE CONVECTION
IS AGAIN EXPECTED TO DEVELOP THIS AFTERNOON. MLCAPE OF 500-1500
J/KG AND DEEP-LAYER SLY SHEAR OF 25-35 KT WILL SUPPORT A RISK OF
ISOLATED LARGE HAIL GIVEN RELATIVELY COOL MID LEVEL
TEMPERATURES...AS WELL AS A FEW STRONG GUSTS WITH A DEEPLY-MIXED
BOUNDARY LAYER.

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