DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 131632
SWODY1
SPC AC 131629

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1129 AM CDT THU JUN 13 2013

VALID 131630Z - 141200Z

...THERE IS A MDT RISK OF SVR TSTMS ACROSS SOUTHEAST VIRGINIA AND
NORTHEAST NORTH CAROLINA...

...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK AREA
FROM DELMARVA/SRN NJ TO MS/AL/GA...

...THERE IS A SLGT RISK OF SVR TSTMS OVER MUCH OF THE NRN AND
CENTRAL HIGH PLAIN AND PARTS OF THE FRONT RANGE....

...SYNOPSIS...
HIGHLY AMPLIFIED FLOW REGIME WILL SUPPORT A CONTINUATION OF ACTIVE
SEVERE WEATHER ACROSS BOTH THE EAST AND WEST TODAY.

...MID ATLANTIC TO DEEP SOUTH...
A PROGRESSIVE SHORTWAVE TROUGH ACCOMPANIED BY 40-50KT MID-LEVEL JET
STREAK WILL CONTINUE TO DIG EAST-SOUTHEAST ACROSS CENTRAL
APPALACHIANS TO THE MID ATLANTIC REGION THROUGH THE LATE
AFTERNOON/EARLY EVENING. THIS SYSTEM IS LENDING SUPPORT TO SURFACE
LOW PRESSURE CENTER THAT WAS LOCATED NEAR THE NY/PA BORDER WITH A
COLD FRONT EXTENDING SWWD TO CNTRL KY AND THEN WWD TO THE SRN
PLAINS. WITH MORNING MCS NOW OFF THE JERSEY SHORE...FOCUS FOR MORE
WIDESPREAD SEVERE STORMS HAS SHIFTED SOUTH TO VA/NC AND POINTS SOUTH
AND WEST.

LEADING MCS DEPARTING THE JERSEY SHORE HAS GENERATED AN E-W
ORIENTED OUTFLOW BOUNDARY LOCATED FROM DE/ERN MD INTO CNTRL/NRN VA
AND WV. TEMPERATURES S OF THE OUTFLOW ARE WARMING WELL INTO THE 80S
OVER CNTRL/SRN VA AND NRN NC. THIS HEATING COMBINED WITH DEWPOINTS
IN THE 70S AND COOL MID-LEVEL TEMPERATURES/STEEP MID-LEVEL LAPSE
RATES WILL YIELD STRONG TO LOCALLY EXTREME INSTABILITY DURING THE
AFTERNOON. ONCE ACROSS THE APPALACHIAN SPINE...EXPECT STORMS TO
CONTINUE TO INCREASE IN VIGOR WHILE DEVELOPING ESEWD SUPPORTED BY
LARGE SCALE ASCENT AND STRENGTHENING SHEAR COINCIDENT WITH DIURNAL
MAXIMUM IN DESTABILIZATION. GIVEN STRENGTHENING WLY FLOW ALOFT AND
MAGNITUDE OF INSTABILITY EXPECT BOWING LINE SEGMENTS AND SUPERCELLS.
DAMAGING WINDS AND LARGE HAIL WILL BE THE PRIMARY SEVERE WEATHER
THREATS BUT AN ISOLATED TORNADO OR TWO WILL BE POSSIBLE WHERE STORMS
INTERACT WITH RESIDUAL OUTFLOW BOUNDARY AND/OR SEA/BAY BREEZES.

...ROCKIES FRONT RANGE TO CENTRAL TO NORTH HIGH PLAINS...
A POTENT UPPER TROUGH OVER THE PACIFIC NW WILL MIGRATE EWD TOWARDS
THE NRN HIGH PLAINS THROUGH FRIDAY MORNING. WATER VAPOR IMAGERY
SHOWS A LEAD DISTURBANCE MOVING NEWD ACROSS UT AND THIS FEATURE WILL
MOVE ACROSS WY AND APPROACH SERN MT BY THE LATE AFTERNOON. ALTHOUGH
THE NRN-CNTRL HIGH PLAINS ARE LARGELY REMOVED FROM GREATER MOISTURE
CONFINED FARTHER S OVER THE SRN PLAINS...ADEQUATE PW /0.7-1.0 INCH/
IN COMBINATION WITH VERY STEEP LAPSE RATES AND FORCING FOR ASCENT
/DCVA/HEIGHT FALLS/ WILL LEAD TO ISOLD-WIDELY SCTD STORMS DEVELOPING
BY THE AFTERNOON.

STRONG/DEEP SWLY WIND PROFILES WILL PROMOTE STORM ORGANIZATION WHERE
DEWPOINTS CAN REMAIN IN THE UPPER 40S-MID 50S. INITIALLY ISOLATED
HIGH-BASED CONVECTION IS FORECAST TO EXPAND IN AREAL COVERAGE AND
MOVE DOWNSTREAM FROM WRN WY NEWD INTO ERN WY/SRN MT. ISOLATED SEVERE
WIND GUSTS WILL BE THE PREDOMINATE THREAT WITH STORMS LOCATED
FARTHER W IN DRIER/DEEPLY MIXED AIRMASS. WIDELY SCATTERED STORMS
ARE EXPECTED TO DEVELOP FARTHER E ALONG LEE TROUGH EXTENDING FROM A
WEAK LOW OVER SERN MT INTO ERN CO.

FORECAST SOUNDINGS OVER SERN MT/NERN WY SHOW MODERATE INSTABILITY
1000-2000 J/KG MLCAPE AND STRONG DEEP-LAYER SHEAR...SUPPORTIVE OF
ISOLATED SUPERCELLS. AN ATTENDANT LARGE HAIL/SEVERE WIND GUST THREAT
MAY ACCOMPANY THE STRONGEST STORMS...INCLUDING THE POSSIBILITY FOR A
TORNADO...SWD ALONG THE LEE TROUGH BEFORE THIS ACTIVITY WEAKENS
OWING TO NOCTURNAL STABILIZATION.

..CARBIN/SMITH/GARNER.. 06/13/2013

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