DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 082001
SWODY1
SPC AC 081959

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0259 PM CDT SUN JUL 08 2012

VALID 082000Z - 091200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM PORTIONS OF THE
MISSISSIPPI VALLEY EAST TO THE MID-ATLANTIC COAST...

EXPANDED THE WESTERN EXTENSION OF THE SLIGHT RISK AREA ACROSS
CENTRAL/SOUTHERN MO AND NORTHERN AR WHERE ADDITIONAL SVR TSTM
DEVELOPMENT IS EXPECTED THROUGH THE REMAINDER OF AFTERNOON. SBCAPE
IN THIS AREA RANGES FROM 2000-LOCALLY 4000 J/KG AND EXPECT
STORM-SCALE BOUNDARY INTERACTIONS TO RESULT IN ADDITIONAL
DEVELOPMENT. DAMAGING WINDS REMAIN THE PRIMARY THREAT.

MADE MINOR ADJUSTMENTS TO THE 30 PERCENT WIND PROBABILITY OVER THE
MID-ATLANTIC BASED ON CURRENT RADAR TRENDS. ALTHOUGH CONFIDENCE IS
NOT HIGH...STORMS IN THIS AREA ARE IN CLOSER PROXIMITY TO STRONGER
MID-LEVEL FLOW AND WILL CONTINUE TO POSE A THREAT FOR DAMAGING WINDS
AND ISOLATED LARGE HAIL INTO THE EVENING HOURS.

..BUNTING.. 07/08/2012

.PREV DISCUSSION... /ISSUED 1116 AM CDT SUN JUL 08 2012/

...CENTRAL VA INTO THE DELMARVA REGION...
A LONG WAVE TROUGH IS FORECAST TO REMAIN OVER THE NERN STATES AS A
SERIES OF VORTICITY MAX/SHORT WAVE TROUGHS MOVE SEWD/EWD ACROSS SRN
ONTARIO AND QUEBEC. THE SRN EDGE OF STRONGER NWLY FLOW ALOFT IS
EXPECTED TO TRANSLATE SLOWLY SWD ACROSS THE MID ATLANTIC REGION AS
THE LONG WAVE TROUGH GRADUALLY DEEPENS...AS AN ASSOCIATED SURFACE
COLD FRONT SAGS SWD ACROSS THE REGION. VERY WARM/MOIST CONDITIONS
PERSIST FROM NEAR THE COLD FRONT SWD INTO THE WARM SECTOR. WITH
MINIMAL CLOUDS OVER THE REGION STRONG DIABATIC HEATING IN THE
PRE-CONVECTIVE ENVIRONMENT WILL CONTINUE THIS AFTERNOON WITH SURFACE
TEMPERATURES REACHING THE 100-105 RANGE. 12Z IAD RAOB INDICATES
STEEP LAPSE RATES BELOW ~600 MB...AND WHEN COUPLED WITH AMPLE LOW
LEVEL MOISTURE MLCAPE WILL REACH 3500-4000 J/KG.

THUNDERSTORMS ARE EXPECTED TO DEVELOP BY EARLY/MID AFTERNOON OVER
PARTS OF NRN VA AND MD WITH POTENTIALLY RAPID INTENSIFICATION AS
THEY SPREAD/DEVELOP EWD AND SEWD INTO THE EVENING HOURS. MID LEVEL
WIND SPEEDS OF 20-30 KT AND RESULTANT DEEP LAYER SHEAR WILL PROMOTE
A FEW ORGANIZED MULTICELL CLUSTERS/SHORT LINE SEGMENTS CAPABLE OF
PRODUCING DAMAGING WIND GUSTS /ENHANCED BY DCAPE OF 1000-1500 J PER
KG/ AND OCCASIONAL LARGE HAIL.

...APPALACHIANS WWD ACROSS PARTS OF THE OH AND MIDDLE MS VALLEYS...
THE AFOREMENTIONED COLD FRONT EXTENDS WWD ACROSS SRN PARTS OF
INDIANA AND IL INTO CENTRAL MO...AND IS EXPECTED TO SAG SLOWLY SWD
INTO TONIGHT. STRONG DIABATIC HEATING ALONG THE FRONTAL ZONE WITHIN
A VERY MOIST AND UNSTABLE ENVIRONMENT /MLCAPE OF 2500-3500 J/KG
EXPECTED THIS AFTERNOON/ WILL WEAKEN THE CAP SUFFICIENTLY FOR
THUNDERSTORMS TO INCREASE THIS AFTERNOON. WATER VAPOR IMAGERY SHOWS
CYCLONIC PERTURBATION ALONG THE MOISTURE DISCONTINUITY OVER THE
MID-SOUTH REGION AND AS THIS FEATURE MOVES NWWD THIS AFTERNOON...IT
MAY ENHANCE CONVECTIVE DEVELOPMENT OVER THE LOWER OH/MIDDLE MS
VALLEY AREA. ALTHOUGH WINDS ALOFT AND VERTICAL SHEAR ARE EXPECTED
TO REMAIN WEAK FAVORING PRIMARILY PULSE STORMS...POTENTIAL EXISTS
FOR SEVERAL MORE PERSISTENT CLUSTERS TO DEVELOP IF CONVECTIVE
OUTFLOWS ARE ABLE TO BECOME ORGANIZED ON THE MESOSCALE.

...CENTRAL AND ERN PARTS OF OREGON/WA...
WATER VAPOR IMAGERY SHOWS INCREASING MID LEVEL MOISTURE OVER OREGON
IN ADVANCE OF A WEAK VORTICITY MAX CURRENTLY OFF THE NRN CA COAST.
AS THE VORTICITY MAX LIFTS NNEWD...SLY MID/UPPER LEVEL WINDS ARE
FORECAST TO STRENGTHEN WITH A RESULTANT INCREASE IN DEEP LAYER SHEAR
OVER THE AREA. STRONG AFTERNOON HEATING AND SUFFICIENT MOISTURE
AIDED BY OROGRAPHIC FORCING FOR ASCENT IS EXPECTED TO RESULT IN
HIGH-BASED THUNDERSTORM DEVELOPMENT BY MID/LATE AFTERNOON...WITH
ACTIVITY SPREADING NWD FROM OREGON INTO WA THROUGH THE EVENING.
STRONGER STORMS WILL BE CAPABLE OF PRODUCING STRONG WIND GUSTS AND
ISOLATED HAIL.

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