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 171947
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0247 PM CDT TUE MAY 17 2011
   
   VALID 172000Z - 181200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS IN THE VA AREA...
   
   ...MID ATLANTIC...
   AT MID AFTERNOON...STRONG VORTICITY MAX HAD SHIFTED NWWD INTO SRN VA
   TO NEAR LYH...WITH STRONGER FORCING LOCATED IN WRN/NRN VA. AS VORT
   MAX TURNS MORE WWD TOWARD WV...STRONGER FORCING WILL SPREAD INTO
   VA...THOUGH DENSER CLOUDS AND STABLE BOUNDARY LAYER WILL LIMIT WWD
   EXTENT OF SEVERE STORMS. WHILE STORMS THUS FAR HAVE BEEN MOSTLY SUB
   SEVERE...WITH A FEW DEGREES HEATING...A FEW SEVERE STORMS ARE STILL
   POSSIBLE ACROSS NRN AND WRN VA. THE COLD AIR MASS ALOFT SUGGEST HAIL
   IS THE MAIN THREAT.
   
   SINCE STRONGER FORCING HAS MOVED NWWD OUT OF NC AND DRIER AIR IS
   SLOWLY FILTERING IN AT THE LOWER LEVELS...ONLY LOW SEVERE
   PROBABILITIES REMAIN IN NRN NC. ALSO SEVERE PROBABILITIES WERE
   LOWERED IN PA AS THE MAIN FORCING SHOULD REMAIN SOUTH OF STATE.
   
   ...CENTRAL HIGH PLAINS...
   AS UPPER SHORTWAVE TROUGH LIFTS NEWD FROM SWRN CO/NERN NM...STORMS
   ARE LIKELY TO DEVELOP NEAR THE CO/KS BORDER BETWEEN 21-00Z...WITH
   SHEAR AND INSTABILITY SUPPORTIVE OF ISOLATED SEVERE WEATHER.
   HOWEVER...THE BOUNDARY LAYER AIR MASS IMMEDIATELY EAST OF THIS AREA
   IS STABLE...SO ANY SEVERE STORMS THAT FORM ARE NOT EXPECTED TO STAY
   SEVERE VERY LONG.  WILL MAINTAIN LOW SEVERE PROBABILITIES WITH ONLY
   MINOR ADJUSTMENTS TO GRAPHICAL LINES.
   
   ..IMY.. 05/17/2011
   
   .PREV DISCUSSION... /ISSUED 1125 AM CDT TUE MAY 17 2011/
   
   ...MID ATLANTIC...
   
   STRONG VORTICITY MAXIMUM OVER CNTRL/ERN NC AS OF LATE MORNING WILL
   PIVOT NWWD TODAY IN RESPONSE TO UPSTREAM IMPULSE TRANSLATING SEWD
   THROUGH THE SRN APPALACHIANS.  IN THE LOW LEVELS...AN ASSOCIATED
   SURFACE LOW OVER CNTRL NC WILL CONCURRENTLY DEVELOP NWWD INTO WRN VA
   BY TONIGHT.  DCVA IN ADVANCE OF VORTICITY MAXIMUM COUPLED WITH WEAK
   LOW-LEVEL WAA WILL SUPPORT A GRADUAL INCREASE IN TSTM COVERAGE THIS
   AFTERNOON ACROSS THE REGION.  
   
   WHILE THE BOUNDARY LAYER IS NOT OVERLY MOIST...THE PRESENCE OF 500
   MB TEMPERATURES AROUND -18 C WILL CONTRIBUTE TO AIR MASS
   DESTABILIZATION WITH MLCAPE APPROACHING 1000 J/KG IN AREAS WHERE THE
   STRONGEST DIABATIC WARMING OCCURS.  WHEN COUPLED WITH 40-45 KT
   MIDLEVEL JET STREAK AND RESULTANT 35-40 KT OF DEEP SELY
   SHEAR...SETUP WILL FAVOR THE DEVELOPMENT OF ORGANIZED
   STORMS...INCLUDING SUPERCELLS...CAPABLE OF LOCALLY DAMAGING WINDS
   AND PERHAPS SOME HAIL.  AN ISOLATED TORNADO IS POSSIBLE WITH ANY
   STORMS THAT CAN FAVORABLY INTERACT WITH THE SYNOPTIC WARM FRONT
   AND/OR DIFFERENTIAL HEATING/OUTFLOW BOUNDARIES PRESENT WITHIN WARM
   SECTOR.
   
   FOR ADDITIONAL NEAR TERM GUIDANCE ON THIS AREA...SEE MCD 796.
   
   ...CNTRL HIGH PLAINS...
   
   VORTICITY MAXIMUM AND ATTENDANT 50-55 KT MIDLEVEL JET STREAK OVER
   WRN CO INTO NWRN NM AS OF MID MORNING WILL TRANSLATE NEWD
   TODAY...WITH HEIGHT FALLS/DYNAMIC FORCING FOR ASCENT PROGRESSIVELY
   OVERSPREADING LEE CYCLONE AND DEVELOPING DRYLINE SITUATED ACROSS ERN
   CO INTO THE WRN OK/TX PNHDLS.  DESPITE THE FAVORABLY TIMED ARRIVAL
   OF THIS IMPULSE...THE PRESENCE OF CONSIDERABLE LEE MOUNTAIN CIRRUS
   /AND ITS POTENTIAL NEGATIVE IMPACT ON DAYTIME HEATING/ COMBINED WITH
   MARGINAL BOUNDARY LAYER MOISTURE CONTENT WILL TEND TO LIMIT MLCAPE
   TO LESS THAN 1000 J/KG THIS AFTERNOON E OF DRYLINE.  
   
   THE PRESENCE OF THE STEEP LAPSE RATES AND VERTICALLY VEERING WIND
   PROFILES WITH 40-50 KT OF DEEP-LAYER SHEAR WILL BE SUPPORTIVE OF
   ISOLATED OCCURRENCES OF DAMAGING WINDS AND/OR SEVERE HAIL WITH ANY
   STORMS THAT DEVELOP LATE THIS AFTERNOON INTO EVENING.  BUT...THE
   POTENTIAL FOR A MORE ORGANIZED SEVERE WEATHER EPISODE WILL LIKELY BE
   TEMPERED BY THE MARGINAL BOUNDARY LAYER MOISTURE CONTENT.
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z