Apr 21, 2015 0100 UTC Day 1 Convective Outlook
Updated: Tue Apr 21 00:58:08 UTC 2015 (20150421 0100Z Day 1 shapefile | 20150421 0100Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20150421 0100 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 42,585 17,175,149 Baltimore, MD...Washington, DC...Richmond, VA...Arlington, VA...Alexandria, VA...
MARGINAL 116,042 35,989,692 New York, NY...Philadelphia, PA...Charlotte, NC...Virginia Beach, VA...Raleigh, NC...
Probabilistic Tornado Graphic
20150421 0100 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.
Day 1 Tornado Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
2 % 54,798 18,779,244 Philadelphia, PA...Baltimore, MD...Raleigh, NC...Durham, NC...Richmond, VA...
Probabilistic Damaging Wind Graphic
20150421 0100 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.
Day 1 Wind Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
15 % 31,608 13,682,810 Baltimore, MD...Washington, DC...Richmond, VA...Arlington, VA...Alexandria, VA...
5 % 114,417 24,750,217 Philadelphia, PA...Charlotte, NC...Virginia Beach, VA...Raleigh, NC...Norfolk, VA...
Probabilistic Large Hail Graphic
20150421 0100 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.
Day 1 Hail Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
15 % 30,656 15,550,828 Baltimore, MD...Washington, DC...Arlington, VA...Alexandria, VA...Allentown, PA...
5 % 105,722 35,428,991 New York, NY...Philadelphia, PA...Charlotte, NC...Raleigh, NC...Newark, NJ...
   SPC AC 210058

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0758 PM CDT MON APR 20 2015

   VALID 210100Z - 211200Z

   ...THERE IS A SLGT RISK OF SVR TSTMS FOR PARTS OF THE MID-ATLANTIC
   STATES...

   ...THERE IS A MRGL RISK OF SVR TSTMS SURROUNDING THE SLGT RISK TO
   THE CAROLINAS...

   ...SUMMARY...
   ISOLATED SEVERE STORMS WILL REMAIN POSSIBLE EARLY TONIGHT ACROSS THE
   MID-ATLANTIC STATES.

   ...MID-ATLANTIC STATES...
   SCATTERED TSTMS FROM SRN NY TO NRN NC SHOULD PERSIST THROUGH ABOUT
   MIDNIGHT AS MID-LEVEL HEIGHT FALLS ARE MAINTAINED WITH A SHORTWAVE
   IMPULSE OVER THE MIDWEST AMPLIFYING ON APPROACH TO THE NRN
   APPALACHIANS. HOWEVER...WARM SECTOR LOW-LEVEL WINDS ARE CONSISTENTLY
   PROGGED TO BECOME INCREASINGLY VEERED WHICH SHOULD WEAKEN
   CONVERGENCE ALONG THE COLD FRONT THAT WILL REACH THE COAST TUESDAY
   MORNING. 00Z IAD RAOB SAMPLED THE GREATEST INSTABILITY OF AREA
   THERMODYNAMIC PROFILES WITH STEEP LOW/MID-LEVEL LAPSE RATES...BUT
   MLCAPE ONLY AROUND 500 J/KG. OVERALL SEVERE RISK SHOULD DIMINISH
   THIS EVENING DUE TO WIDESPREAD WEAK BUOYANCY AND NOCTURNAL
   BOUNDARY-LAYER STABILIZATION. ALTHOUGH WEAKNESSES IN HODOGRAPHS ARE
   PERVASIVE IN 00Z RAOBS FROM 2-5 KM AGL...DEEP-LAYER SHEAR IS
   SUFFICIENT TO SUPPORT ORGANIZED CLUSTERS FROM MAINLY VA TO PA WITH
   THE MAIN RISK BEING ISOLATED SEVERE HAIL/DAMAGING WIND.

   ..GRAMS.. 04/21/2015

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0600Z