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 041629
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1129 AM CDT WED MAY 04 2011
   
   VALID 041630Z - 051200Z
   
   ...NO SVR TSTM AREAS FORECAST...
   
   ...SYNOPSIS...
   AS A RELATIVELY AMPLIFIED UPPER TROUGH APPROACHES THE ATLANTIC
   SEABOARD...A LOW/MID-LEVEL CYCLONE IS EXPECTED TO DEEPEN ACROSS THE
   NORTHEASTERN U.S. THROUGH EARLY THURSDAY.  VARIABILITY EXISTS AMONG
   THE MODELS...BUT IT APPEARS THAT THE PRIMARY SURFACE DEVELOPMENT
   WILL TAKE PLACE ALONG A FRONTAL ZONE NEAR THE NEW ENGLAND COAST
   LATER THIS AFTERNOON AND EVENING...BEFORE MIGRATING INLAND ACROSS
   PARTS OF MAINE AND THE CANADIAN MARITIMES LATE TONIGHT INTO
   THURSDAY.  AS THIS OCCURS...THE TRAILING SURFACE FRONT WILL ADVANCE
   EAST OF MUCH OF THE ATLANTIC COAST...AND SOUTHWARD THROUGH MUCH OF
   THE REMAINDER OF THE FLORIDA PENINSULA.
   
   ...ATLANTIC SEABOARD...
   SCATTERED THUNDERSTORMS ARE ONGOING NEAR OR JUST ABOVE/WEST OF THE
   SURFACE FRONT ALONG MID ATLANTIC COASTAL AREAS.  THIS ACTIVITY IS
   EXPECTED TO DIMINISH/SHIFT INTO THE WESTERN ATLANTIC BY
   18-21Z...HOWEVER NEW DEVELOPMENT APPEARS POSSIBLE IN ASSOCIATION
   WITH FAVORABLE LARGE SCALE FORCING FOR UPWARD VERTICAL MOTION NEAR
   NEW ENGLAND COASTAL AREAS LATE THIS AFTERNOON INTO TONIGHT.  THESE
   STORMS ARE LIKELY TO REMAIN BASED ABOVE A STABLE SURFACE BASED
   LAYER...WITH WEAK CAPE FURTHER LIMITING ANY SEVERE POTENTIAL TO
   NEGLIGIBLE LEVELS.  
   
   OTHER THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON WITH BOUNDARY LAYER
   DESTABILIZATION ALONG AND SOUTH OF THE FRONT ACROSS THE FLORIDA
   PENINSULA.  HIGHEST PROBABILITIES APPEAR TO EXIST ACROSS THE
   INTERIOR CENTRAL PENINSULA INTO COASTAL AREAS SOUTH OF TAMPA. 
   MODEST INSTABILITY IS EXPECTED TO LIMIT STORM STRENGTH.
   
   ...PLAINS...
   MOISTURE LEVELS ARE GENERALLY LOW ACROSS MUCH OF THE CENTRAL
   U.S...WHICH IS EXPECTED TO LIMIT CONVECTIVE POTENTIAL  BUT...A COLD
   MID-LEVEL TROUGH CHARACTERIZED BY 500 MB TEMPERATURES AT OR BELOW
   -20C MAY CONTRIBUTE TO STEEP LAPSE RATES WITH DAYTIME
   HEATING...ACROSS THE HIGHER TERRAIN NEAR AND JUST EAST OF THE
   NORTHERN ROCKIES...AND JUST AHEAD OF A DEVELOPING SURFACE FRONT
   LIKELY TO ADVANCE SOUTHEASTWARD INTO THE MID MISSOURI VALLEY AND
   CENTRAL PLAINS BY LATE AFTERNOON.  HIGHEST THUNDERSTORM
   PROBABILITIES APPEAR TO EXIST IN A ZONE OF ENHANCED LOWER/MID
   TROPOSPHERIC WARM ADVECTION...JUST AHEAD OF A CYCLONIC VORTICITY
   MAXIMA EMBEDDED WITHIN THE UPPER TROUGH...ACROSS EASTERN NEBRASKA
   INTO PARTS OF SOUTHEASTERN SOUTH DAKOTA AND WESTERN IOWA DURING THE
   LATE AFTERNOON/EARLY EVENING HOURS.  IN GENERAL THOUGH... COVERAGE
   OF STORMS ACROSS THE REGION IS EXPECTED TO BE SPARSE... WITH LOW TO
   NEGLIGIBLE SEVERE POTENTIAL.
   
   ..KERR.. 05/04/2011
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

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