Jun 13, 2013 1630 UTC Day 1 Convective Outlook
Updated: Thu Jun 13 16:33:41 UTC 2013
Probabilistic to Categorical Outlook Conversion Table
Public Severe Weather Outlook

The SPC is forecasting ...severe thunderstorms expected over parts of the mid atlantic states today....   Please read the latest public statement about this event.  View What is a Watch? clip.

Categorical Graphic
20130613 1630 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20130613 1630 UTC Day 1 Tornado Probabilities Graphic
Probability of a tornado within 25 miles of a point.
Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point.
Probabilistic Damaging Wind Graphic
20130613 1630 UTC Day 1 Damaging Wind Probabilities Graphic
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point.
Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Probabilistic Large Hail Graphic
20130613 1630 UTC Day 1 Large Hail Probabilities Graphic
Probability of hail 1" or larger within 25 miles of a point.
Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.
Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
MODERATE 34,798 6,910,895 Virginia Beach, VA...Raleigh, NC...Greensboro, NC...Norfolk, VA...Durham, NC...
SLIGHT 518,840 45,883,491 Charlotte, NC...Denver, CO...Baltimore, MD...Washington, DC...Nashville, TN...
   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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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z