Categorical Graphic
Probabilistic Tornado 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
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
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.

   SPC AC 271628
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1128 AM CDT SAT AUG 27 2011
   
   VALID 271630Z - 281200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ALONG THE MIDDLE ATLANTIC
   COAST...
   
   ...MIDDLE ATLANTIC COAST...
   LATEST NHC FORECASTS INDICATE IRENE WILL CONTINUE TRACKING NNEWD
   ACROSS EXTREME ERN NC THIS AFTERNOON AND ALONG THE DELMARVA AND NEW
   JERSEY COASTS TONIGHT.  DENSE OVERCAST WITHIN THE LARGE CIRCULATION
   WILL LIMIT DIABATIC HEATING DOWNSTREAM OF THE CENTER...BUT SURFACE
   DEW POINTS IN THE LOW/MID 70S WILL CONTRIBUTE TO MARGINAL
   INSTABILITY /MLCAPE GENERALLY AOB 500 J PER KG/ SUPPORTIVE OF
   OCCASIONAL THUNDERSTORMS...ESPECIALLY OVER THE COASTAL WATERS AND
   ADJACENT INLAND AREAS.  CONVECTIVE BANDS NORTH OF THE CENTER OF
   IRENE HAVE CONTAINED EMBEDDED SMALL SUPERCELLS THIS MORNING MOVING
   ONSHORE FROM THE TIDEWATER NORTHWARD INTO ERN MD.  THESE HAVE TENDED
   TO WEAKEN AFTER MOVING INLAND WHERE INSTABILITY DECREASES WITH
   DISTANCE FROM THE COAST.  VERY STRONG LOW LEVEL VERTICAL
   SHEAR/STORM-RELATIVE HELICITY IN ADVANCE OF IRENE WILL SUPPORT A FEW
   SMALL SUPERCELLS WITHIN THE CONVECTIVE BANDS NORTH OF THE CENTER
   WITH CONTINUED POTENTIAL FOR ISOLATED TORNADOES TO OCCUR.
   
   ...SD/NEB TONIGHT...
   MODEL GUIDANCE IS CONSISTENT INDICATING A LOW AMPLITUDE SHORT WAVE
   TROUGH WILL MOVE SEWD TONIGHT FROM THE NRN PLAINS AND ENHANCE
   CONVECTIVE POTENTIAL OVER PARTS OF SD AND NEB TONIGHT.  STEEP MID
   LEVEL LAPSE RATES ATOP SUFFICIENT LOW MOISTURE WILL RESULT IN
   ELEVATED INSTABILITY WITH MUCAPE OF 2000-3000 J/KG.  LOW LEVEL WARM
   ADVECTION ASSOCIATED WITH A 30-35 KT SWLY NOCTURNAL LOW LEVEL JET
   WILL AID IN DEVELOPMENT OF AN ELEVATED MCS...WHICH MAY BECOME MORE
   ORGANIZED DURING THE OVERNIGHT HOURS.  STEEP LAPSE RATES AND
   FAVORABLE CLOUD LAYER SHEAR SUGGEST POTENTIAL FOR STRONGER CELLS TO
   PRODUCE HAIL.  THIS AREA WILL BE MONITORED CLOSELY AND AN UPGRADE TO
   SLIGHT RISK MAY BE NEEDED IN LATER OUTLOOKS.
   
   ..WEISS/GRAMS.. 08/27/2011
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z