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 300100
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0800 PM CDT FRI JUN 29 2012
   
   VALID 300100Z - 301200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS PORTIONS EXTREME ERN
   WV...VA...MD...DC..EXTREME SRN PA...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ELSEWHERE FROM ERN WV TO
   COASTAL SRN MID-ATLC AND VA/MD/DE TIDEWATER....
   
   ...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS SWRN MN AND IA TO NWRN
   INDIANA...
   
   ...SYNOPSIS...
   UPPER-AIR PATTERN WILL REMAIN DOMINATED BY MEAN RIDGING ACROSS MOST
   OF SRN 1/2 OF CONUS.  RIDGING EXTENDS FROM AZ-SC AND BEYOND...BUT IS
   BREACHED SOMEWHAT BY COL/TROUGH OVER OK EXTENDING NWD FROM
   BROAD/WEAK/QUASISTATIONARY/UPPER LOW OVER S TX.  GEN RIDGING ALOFT
   ALSO EXTENDS FROM 4-CORNERS REGION NNWWD OVER NRN ROCKIES TO AB AND
   WILL MOVE SLOWLY EWD OUT OF NRN ROCKIES BY 12Z.  SYNOPTIC-SCALE
   TROUGHING IS EVIDENT OVER HUDSON BAY REGION...AND OFFSHORE PAC
   COAST.  SHORTWAVES EMBEDDED IN INTERVENING FLOW WILL INFLUENCE THIS
   FCST...INCLUDING NEARLY-PHASED TROUGHS NOW OVER SWRN MN/NWRN IA AND
   S-CENTRAL/SERN IA.  LATTER PERTURBATION WAS CONVECTIVELY ENHANCED
   LAST NIGHT OVER CENTRAL PLAINS...AND MAY EXPERIENCE FURTHER
   CONVECTIVE VORTICITY GENERATION WITH ONGOING IA ACTIVITY.  COMBINED
   TROUGHS SHOULD MOVE ESEWD ACROSS UPPER MS VALLEY AND IL TO INDIANA
   BY END OF PERIOD.  UPSTREAM...MOISTURE CHANNEL IMAGERY INDICATES
   SHORTWAVE TROUGH PENETRATING MEAN RIDGE POSITION OVER AB...WHICH
   WILL PIVOT EWD/ESEWD ACROSS SK/MB OVERNIGHT...INFLUENCING ELEVATED
   TSTM POTENTIAL LATE IN PERIOD OVER ND.
   
   AT SFC...23Z ANALYSIS SHOWED COLD FRONT FROM SRN QUE ACROSS WRN
   MAINE THEN SWWD OVER CENTRAL/SRN PA...BEING OVERTAKEN BY NRN PORTION
   OF DERECHO-PRODUCING MCS OVER SWRN PA.  OUTFLOW BOUNDARY FROM THAT
   MCS EXTENDS FROM ERN KY NWWD ACROSS SWRN INDIANA TO ERN
   IL...BECOMING QUASISTATIONARY ALONG ERN IL/INDIANA SEGMENT. 
   BOUNDARY BECOMES DIFFUSE NWWD ACROSS CENTRAL IL TO LOW OVER SERN
   IA...INTERSECTING OUTFLOW FROM ONGOING IA CONVECTION.  THAT
   BOUNDARY...IN TURN EXTENDED FROM LOW SWWD NEAR IA/MO BORDER THEN
   WNWWD ACROSS EXTREME SRN IA AND ERN NEB.  QUASISTATIONARY
   FRONT/TROUGH EXTENDED FROM HEAT LOW OVER KS/CO BORDER REGION ENEWD
   ACROSS KS/NEB BORDER TO NWRN MO.
   
   ...WV TO DELMARVA COAST...
   SVR MCS...CONTAINING LARGE BOW ECHO...SHOULD CONTINUE ONGOING
   DERECHO EVENT ESEWD ACROSS APPALACHIANS/PIEDMONT TOWARD VA/MD
   TIDEWATER REGION.  SOME UNCERTAINTY EXISTS WITH RECOVERY AFTER
   CURRENT/SLGT WEAKENING TREND DURING ITS PASSAGE ACROSS RELATIVELY
   DRY AIR IN HIGHEST TERRAIN...HOWEVER
   1. SUBSTANTIAL COLD POOL HAS BEEN BUILT WITH INTENSE ISALLOBARIC
   TENDENCIES TO DRIVE STG LOW-LEVEL FORCING ONTO LOWER TERRAIN...AND
   2. FOREGOING BOUNDARY-LAYER AIR MASS WILL REMAIN SUITABLY
   MOIST/UNSTABLE PER IAD RAOB THAT CONTAINED 2 INCH PW AND OVER 5500
   J/KG MLCAPE.
   
   EXPECT CONTINUED/REJUVENATED DAMAGING WIND POTENTIAL...INCLUDING
   OCNL SIGNIFICANT/65+ KT GUSTS...AT LEAST AS FAR E AS I-95 CORRIDOR. 
   E OF THERE...ACROSS CHESAPEAKE BAY AND DELMARVA...AIR MASS WILL BE
   MORE STABLE...BOTH WITH EWD EXTENT AND WITH TIME.  HOWEVER...FORCED
   ASCENT ALONG COLD-POOL SLAB MAY OVERCOME RELATED CINH AND MAINTAIN
   DAMAGING-WIND THREAT TO COAST.  GIVEN THOSE
   UNCERTAINTIES...PROBABILITIES RAMP DOWN SOMEWHAT FROM BAY EWD...BUT
   REMAIN ABOVE THRESHOLDS FOR CATEGORICAL SVR-WIND OUTLOOK.  REF SPC
   WW 438 AND RELATED MESOSCALE DISCUSSIONS FOR NEAR-TERM FCST INFO ON
   THIS EVENT.
   
   ...UPPER MS VALLEY TO PORTIONS IL/INDIANA...
   SVR POTENTIAL IS CONTINUING ACROSS MS RIVER INTO IL WITH TSTMS  OVER
   ERN IA...WITH ADDITIONAL RISK FOR LARGE HAIL FROM TRAILING
   CONVECTION BEHIND INITIAL OUTFLOW BOUNDARY.  ORGANIZATION WILL BE
   AIDED BY LARGE-SCALE ASCENT ACCOMPANYING MCV...LOW-LEVEL INFLOW AIR
   MASS CONTAINING TEMPS 80S/90S F AND DEW POINTS UPPER 60S/LOW 70S N
   OF BOUNDARY...AND 40-50 KT EFFECTIVE SHEAR MAGNITUDES ALSO AIDED BY
   PERTURBATION ALOFT.  FOR MORE NEAR-TERM DETAILS...REF SPC WW 437 AND
   RELATED MESOSCALE DISCUSSIONS.  UNCERTAINTIES INCREASE WITH EWD
   EXTENT REGARDING DURATION/STRENGTH/COVERAGE OF THIS ACTIVITY PAST
   NRN IL...GIVEN GROWING STATIC STABILITY RELATED TO EARLIER MCS
   PASSAGE...AND EXTENT OF NEARLY SFC-BASED AIR MASS RECOVERY ALONG AND
   N OF BOUNDARY.  AS SUCH...UNCONDITIONAL PROBABILITIES DIMINISH EWD
   TOWARD INDIANA...BUT CONDITIONAL SVR THREAT MAY PERSIST TO END OF
   PERIOD.
   
   ...MAINE...
   SCATTERED TSTMS ALONG PREFRONTAL CONVERGENCE LINE ARE MOVING OVER
   NEW BRUNSWICK AND DOWNEAST MAINE ATTM...AND THEIR SVR POTENTIAL WILL
   DIMINISH THROUGH REMAINDER EVENING WITH STABILIZATION OF
   PRECONVECTIVE BOUNDARY LAYER.  MEANWHILE...ISOLATED SVR HAIL/GUSTS
   STILL MAY OCCUR WITH CONVECTION CLOSER TO SFC COLD FRONT OVER NRN
   MAINE.  THREAT HAS DIMINISHED ENOUGH THAT SUB-CONDITIONAL SVR
   PROBABILITIES CAN BE PULLED BELOW CATEGORICAL OUTLOOK LEVELS...WHILE
   KEPT FOR MRGL POTENTIAL REMAINING.
   
   ...CENTRAL/NRN PLAINS...
   ALTHOUGH ISOLATED/MRGL SVR POTENTIAL EXISTS ACROSS BROAD SWATH OF
   CENTRAL/NRN PLAINS AS OUTLINED BY 5% AREA...MAIN CONCERN FOR
   EVENING/OVERNIGHT ACTIVITY IS FROM NERN SD/SWRN MN SEWD ACROSS IA. 
   SFC ANALYSIS SHOWED WELL-DEFINED MOIST PLUMES/AXES FROM CENTRAL IA
   SWWD ACROSS SRN NEB...AND NWWD OVER SWRN MN TO ERN SD.  SRN MOIST
   PLUME MAY SUPPORT SOME SVR POTENTIAL...BUT MLCINH DERIVED FROM
   MODIFIED OAX/TOP/LBF RAOBS SHOULD STRENGTHEN WITH ONSET OF
   APPRECIABLE SFC COOLING THIS EVENING...ALONG AND N OF
   QUASISTATIONARY FRONT.  FARTHER NW...HOWEVER...UPPER-LEVEL
   SUPPORT/DESTABILIZATION AHEAD OF NRN-STREAM PERTURBATION WILL BECOME
   JUXTAPOSED WITH LOW-LEVEL MOISTURE PLUME...CONDITIONALLY SUPPORTING
   CLUSTERED TSTM DEVELOPMENT AND FORWARD PROPAGATION.  THERE COULD BE
   SOME SPATIAL SEPARATION BETWEEN ERN EDGE OF THIS REGIME AND CURRENT
   LOCATION OF ERN IA COMPLEX...HOWEVER WILL AVOID INTRODUCING NARROW
   GAP BETWEEN 15%/SLGT AREAS GIVEN THAT UNCERTAINTY.
   
   ..EDWARDS.. 06/30/2012
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

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