Jul 26, 2012 2000 UTC Day 1 Convective Outlook
Updated: Thu Jul 26 20:03:35 UTC 2012
Probabilistic to Categorical Outlook Conversion Table
Public Severe Weather Outlook

The SPC is forecasting ...severe thunderstorms including widespread damaging winds expected over parts of the ohio valley to interior southern new england this afternoon into early this evening....   Please read the latest public statement about this event.  View What is a Watch? clip.

Categorical Graphic
20120726 2000 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20120726 2000 UTC Day 1 Tornado Probabilities 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
20120726 2000 UTC Day 1 Damaging Wind Probabilities 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
20120726 2000 UTC Day 1 Large Hail Probabilities 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 262000
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0300 PM CDT THU JUL 26 2012
   
   VALID 262000Z - 271200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS FOR SRN OH...NRN
   WV/MD/DE...PA...NJ...SERN NY...CT...WRN MA...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE WRN GREAT LAKES/MID-MS
   VALLEY TO THE MID-ATLANTIC/SRN NEW ENGLAND...
   
   ...WIDESPREAD DAMAGING WIND EVENT/POTENTIAL DERECHO APPEAR TO BE
   UNFOLDING ACROSS PARTS OF THE NORTHEAST...
   
   ...OH TO SRN NEW ENGLAND...
   ADJUSTED MODERATE RISK TO ALONG AND AHEAD OF INITIAL QLCS IN SWRN NY
   TO ERN OH AND UPSTREAM DEVELOPMENT OCCURRING BACK IN WRN OH.
   ALTHOUGH SEVERE WIND GUSTS HAVE YET TO BE MEASURED BY ANY ASOS/AWOS
   OBSERVATIONS...50-55 KT EWD MOVEMENT HAS BEEN NOTED WITH THIS
   INITIAL LINE AND 18Z PIT/OKX RAOBS ARE CERTAINLY SUPPORTIVE OF FAST
   ELY PROPAGATION. CONSIDERED UPGRADE TO HIGH RISK BUT RELATIVELY
   MODEST MID/HIGH-LEVEL LAPSE RATES SAMPLED IN REGIONAL 18Z RAOBS
   SUGGEST MODERATE RISK APPEARS MOST APPROPRIATE ATTM.
   NEVERTHELESS...NUMEROUS TO WIDESPREAD COVERAGE OF DAMAGING WINDS IS
   LIKELY AS THE NUMBER OF BOWING SEGMENTS INCREASE WITH AN ASSOCIATED
   THREAT OF ISOLATED INTENSE WIND DAMAGE AND BRIEF TORNADOES. 
   
   ...SRN PLAINS TO MID-MS AND TN VALLEYS...
   ADJUSTED SLIGHT RISK SEWD INTO THE TN VALLEY AND ENHANCED WIND
   PROBABILITIES AS TSTMS WILL CONTINUE TO INCREASE FROM THE OZARK
   PLATEAU TO THE LOWER OH VALLEY. ALTHOUGH ON THE FRINGE OF STRONGER
   WLYS...HOT TEMPERATURES AND LARGE BUOYANCY SHOULD RESULT IN
   STRENGTHENING COLD POOLS. THIS SHOULD LEAD TO PROBABLE MCS
   DEVELOPMENT AND PROPAGATION SHOULD TEND TOWARDS THE TN VALLEY.
   
   ...WI AREA...
   SEE PREVIOUS OUTLOOK DISCUSSION.
   
   ..GRAMS.. 07/26/2012
   
   .PREV DISCUSSION... /ISSUED 1130 AM CDT THU JUL 26 2012/
   
   ...SYNOPSIS...
   FAST ZONAL FLOW ALOFT CURRENTLY STRETCHES FROM THE MIDWEST INTO THE
   NERN STATES...WITH AN EMBEDDED LOW AMPLITUDE SHORTWAVE TROUGH
   CURRENTLY DEVELOPING FROM MI INTO IL. AT THE SURFACE...VERY UNSTABLE
   AIR RESIDES SE OF A DIFFERENTIAL HEATING ZONE LEFT OVER FROM MORNING
   CONVECTION...EXTENDING FROM SRN IL NEWD ACROSS NRN IND AND OH. TO
   THE NE...A MORE SUBSTANTIAL OUTFLOW BOUNDARY REMAINS ACROSS CNTRL PA
   INTO NJ...BUT HEATING WILL CONTINUE N OF THE BOUNDARY INTO SRN
   NY...AND JUST S OF ANOTHER DIFFERENTIAL HEATING BOUNDARY ROUGHLY
   FROM SYRACUSE TO ALBANY. WSWLY LOW LEVEL FLOW AND HEATING SHOULD
   HELP ERODE CLOUDS AND ALLOW FOR A RETURN OF WARM AND UNSTABLE AIR
   NWD ACROSS PA...SRN NY...AND EVENTUALLY SRN NEW ENGLAND LATER
   TODAY...PROVIDING A FAVORABLE ENVIRONMENT FOR SEVERE STORM
   MAINTENANCE. 
   
   ELSEWHERE...THE SWRN PORTION OF THIS UPPER SHORTWAVE TROUGH WILL
   EXTEND SWWD ACROSS THE MID MS VALLEY WITH SEVERE STORMS POSSIBLE AS
   FAR SW AS OK. 
   
   ...INDIANA NEWD INTO SRN NEW ENGLAND...
   STRONG HEATING WILL PERSIST OVER MUCH OF THE REGION...WITH SEVERE
   THUNDERSTORM DEVELOPMENT LIKELY TO INITIATE FROM WRN PA SWWD ACROSS
   OH AND IND BY EARLY/MID AFTERNOON. INITIATION WILL FURTHER BE
   ENHANCED BY SEVERAL VORTICITY MAXIMA MOVING THROUGH THE FLOW. MUCAPE
   IN EXCESS OF 3000 J/KG...ALONG WITH 40+ KT LOW TO MIDLEVEL MEAN
   WINDS...SHOULD ALLOW FOR RAPID UPSCALE GROWTH OF AND MERGING OF
   DEVELOPING STORM CELLS INTO LINES CAPABLE OF DAMAGING WINDS AND
   HAIL. AS THESE STORMS CONTINUE EWD ACROSS THE PA/NEW ENGLAND SFC
   BOUNDARIES...THEY MAY EXHIBIT ROTATION WITH PARTICULARLY DAMAGING
   SWATHS OF WINDS ESPECIALLY WITH ANY BOWHEAD/MESO-LOW.
   
   ...ERN LOWER MI EWD ACROSS SWRN ONTARIO AND INTO NY...
   WHILE THE PRIMARY MCS DEVELOPS TO THE S...SUBSTANTIAL MOISTURE WILL
   REMAIN OVER LOWER MI EWD INTO THE LOWER GREAT LAKES...WITH PWAT IN
   EXCESS OF 1.75 INCHES. FLOW ALOFT AND SHEAR WILL REMAIN FAVORABLE
   FOR SEVERE STORMS HERE AS WELL...BUT THE MAIN QUESTION IS COVERAGE.
   IF POCKETS OF INSTABILITY CAN DEVELOP...THEN ADDITIONAL ISOLATED
   SEVERE STORMS MAY OCCUR MAINLY LATE IN THE DAY. 
   
   ...SRN PLAINS TO MID MS VALLEY TODAY...
   THE COMPOSITE OUTFLOW BOUNDARY GENERATED BY OVERNIGHT CONVECTION
   CONTINUES TO MOVE SEWD INTO CENTRAL OK/MO/IL...JUST NW OF I-44. 
   THOUGH THE SYNOPTIC COLD FRONT IS LOCATED FARTHER TO THE
   NW...LINGERING CLOUDS SUGGEST THAT THE GREATER RISK FOR ISOLATED
   SEVERE STORMS WILL BE FOCUSED ALONG THE INITIAL WIND SHIFT AND
   DIFFERENTIAL HEATING ZONE.  DEEP-LAYER UNIDIRECTIONAL WIND PROFILES
   WILL WEAKEN WITH SWWD EXTENT FROM IL TO OK...SUGGESTING THAT
   MULTICELL CLUSTERS WILL BE MORE PREVALENT TOWARD IL...AND PULSE-TYPE
   STORMS ALONG THE WIND SHIFT INTO OK.  MODEST MIDLEVEL LAPSE RATES
   AND INVERTED-V PROFILES WILL FAVOR DAMAGING OUTFLOW GUSTS AS THE
   PRIMARY SEVERE RISK THIS AFTERNOON/EVENING.
     
   ...WI AREA THIS AFTERNOON...
   RESIDUAL BOUNDARY LAYER DEWPOINTS IN THE MID-UPPER 60S AND CLEARING
   OF CONVECTIVE DEBRIS CLOUDS WILL ALLOW DESTABILIZATION ACROSS
   CENTRAL WI BY AFTERNOON.  THE DESTABILIZATION WILL COINCIDE WITH THE
   PASSAGE OF THE SOMEWHAT DIFFUSE SYNOPTIC COLD FRONT AND THE APPROACH
   OF THE BAND OF LOW-MIDLEVEL ASCENT PRECEDING THE SHORTWAVE TROUGH.
   GIVEN MLCAPE IN THE 1000-2000 J/KG RANGE AND STRAIGHT HODOGRAPHS
   WITH 30-40 KT EFFECTIVE BULK SHEAR...A FEW ORGANIZED STORMS WILL BE
   POSSIBLE WITH AN ATTENDANT RISK FOR ISOLATED LARGE HAIL AND DAMAGING
   WINDS.
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

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