Categorical Graphic
Probabilistic Graphic
Probability of severe weather within 25 miles of a point. Hatched Area: 10% or greater probability of significant severe within 25 miles of a point.

   SPC AC 271729
   
   DAY 2 CONVECTIVE OUTLOOK CORR 1
   NWS STORM PREDICTION CENTER NORMAN OK
   1229 PM CDT WED APR 27 2011
   
   VALID 281200Z - 291200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS THURSDAY ALONG MUCH OF THE
   ATLANTIC SEABOARD...
   
   CORRECTED OUTLOOK AND PROBABILITY LINES
   
   ...SYNOPSIS...
   AS UPPER RIDGING REMAINS STRONG OVER THE WESTERN ATLANTIC...AND
   ANOTHER SIGNIFICANT UPPER TROUGH DIGS INTO THE WESTERN U.S...THE
   BROAD CLOSED LOW STILL EVOLVING OVER THE UPPER MIDWEST APPEARS
   LIKELY TO ELONGATE AND LIFT INTO EASTERN CANADA DURING THIS FORECAST
   PERIOD.  AS THIS OCCURS...MODELS INDICATE THAT THE TRAILING UPPER
   TROUGH AXIS...EXTENDING SOUTHWARD IN POSITIVELY TILTED FASHION
   THROUGH MUCH OF THE EASTERN U.S...WILL GRADUALLY SHIFT TOWARD THE
   ATLANTIC COAST.  AN ASSOCIATED COLD FRONT MAY SURGE MORE RAPIDLY
   EASTWARD ACROSS THE NORTHEAST STATES...AS A DEEP SURFACE CYCLONE
   MIGRATES NORTHWARD THROUGH QUEBEC...BUT IT APPEARS THAT THE FRONT
   WILL BE A BIT SLOWER TO THE CLEAR MID AND SOUTHERN ATLANTIC COASTAL
   AREAS.
   
   ...ATLANTIC SEABOARD...
   MODEST PRE-FRONTAL MID-LEVEL LAPSE RATES WILL PROBABLY LIMIT THE
   MAGNITUDE OF DESTABILIZATION THURSDAY...PARTICULARLY ACROSS NORTHERN
   MID ATLANTIC COASTAL AREAS INTO EASTERN NEW YORK AND THE
   HUDSON/CHAMPLAIN VALLEY.  HOWEVER...HIGHER BOUNDARY LAYER MOISTURE
   CONTENT MAY STILL CONTRIBUTE TO MODERATE CAPE ON THE ORDER OF 1000+
   J/KG...FROM THE MID ATLANTIC STATES SOUTHWARD INTO FLORIDA. 
   REGARDLESS...STRONG SOUTHERLY DEEP LAYER FLOW AND SHEAR /30-70 KT AT
   850 MB...50-90 KT AT 500 MB/ ARE EXPECTED TO COMPENSATE FOR ANY
   THERMODYNAMIC DEFICIENCIES...SUPPORTING THE RISK FOR ORGANIZED
   CONVECTIVE DEVELOPMENT CAPABLE OF PRODUCING DAMAGING WINDS...PERHAPS
   ISOLATED TORNADOES.  AN EXCEPTION MAY EXIST TO THE LEE OF THE HIGHER
   TERRAIN ACROSS SOUTHERN INTO NORTHERN NEW ENGLAND...WHERE FLOW OFF
   THE COOL WATERS OF THE NORTHERN ATLANTIC MAY MAINTAIN A STABLE
   BOUNDARY LAYER.  ACROSS THE CENTRAL FLORIDA PENINSULA...WIND
   FIELDS/SHEAR WILL BE MUCH WEAKER...BUT A REMNANT PRE-FRONTAL OUTFLOW
   BOUNDARY MAY ENHANCE LOW-LEVEL CONVERGENCE ALONG THE ATLANTIC COAST
   SEA BREEZE...IN THE PRESENCE OF LARGE CAPE DURING THE PEAK AFTERNOON
   HEATING.
   
   ...LOWER OHIO VALLEY...
   MODELS INDICATE THAT A FAIRLY SIGNIFICANT SHORT WAVE
   IMPULSE/MID-LEVEL LOBE OF CYCLONIC VORTICITY WILL PIVOT
   EAST/SOUTHEASTWARD ACROSS THE REGION DURING THE DAY THURSDAY...TO
   THE SOUTH OF THE ELONGATING CLOSED LOW.  DURING PEAK AFTERNOON
   HEATING...ASSOCIATED LARGE-SCALE FORCING FOR UPWARD VERTICAL MOTION
   IS EXPECTED TO CONTRIBUTE TO CONVECTIVE DEVELOPMENT BENEATH THE
   MID-LEVEL COLD CORE OF THE UPPER TROUGH /500 MB TEMPS OF -22 TO
   -24C/.  RESIDUAL BOUNDARY LAYER MOISTURE COUPLED WITH
   INSOLATION...AND ASSOCIATED STEEPENING OF LOW-LEVEL LAPSE
   RATES...APPEAR LIKELY TO CONTRIBUTE TO SUFFICIENT INSTABILITY FOR
   SCATTERED LOW-TOPPED THUNDERSTORM ACTIVITY.  IN THE PRESENCE OF
   MODERATELY STRONG WESTERLY MEAN LOWER/MID TROPOSPHERIC FLOW...ON THE
   ORDER OF 40 KTS...THERMODYNAMIC PROFILES APPEAR FAVORABLE FOR THE
   DOWNWARD TRANSFER OF HIGHER MOMENTUM TO THE SURFACE.  A FEW
   CONVECTIVELY ENHANCED GUSTS COULD LOCALLY APPROACH OR BRIEFLY EXCEED
   SEVERE LIMITS.
   
   ..KERR.. 04/27/2011
   
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   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z