May 29, 2012 1300 UTC Day 1 Convective Outlook
Updated: Tue May 29 12:55:28 UTC 2012
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20120529 1300 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20120529 1300 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
20120529 1300 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
20120529 1300 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 291252
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0752 AM CDT TUE MAY 29 2012
   
   VALID 291300Z - 301200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO TONIGHT
   FROM THE UPPER OH VALLEY EWD INTO NEW ENGLAND AND THE MID-ATLANTIC
   COAST...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON AND TONIGHT FOR
   PARTS OF THE CNTRL/SRN PLAINS...
   
   ...SYNOPSIS...
   
   AN UPPER-LEVEL LOW ALONG THE MN/ONTARIO BORDER WILL GRADUALLY EVOLVE
   INTO AN OPEN WAVE DURING THE D1 PERIOD AS IT PROGRESSES ENEWD INTO
   WRN QUEBEC.  THIS SYSTEM WILL BE ATTENDED BY A BELT OF 50-60 KT
   MIDLEVEL FLOW AND 500-MB HEIGHT FALLS OF 60-120 M/12-HR WHICH WILL
   OVERSPREAD THE ST. LAWRENCE VALLEY...LOWER GREAT LAKES...AND NEW
   ENGLAND.  ELSEWHERE...MIDLEVEL HEIGHTS WILL REBOUND SLIGHTLY ACROSS
   THE GREAT PLAINS IN THE WAKE OF THE GREAT LAKES SYSTEM...AND AHEAD
   OF AN UPSTREAM UPPER SHORT-WAVE TROUGH TRANSLATING SEWD FROM SRN
   BRITISH COLUMBIA THROUGH THE NRN ROCKIES.
   
   AT THE SURFACE...A COLD FRONT INITIALLY FROM LOW PRESSURE OVER WRN
   QUEBEC SWWD THROUGH SWRN ONTARIO INTO THE MID-MS VALLEY WILL ADVANCE
   EWD INTO NEW ENGLAND AND THE MID-ATLANTIC STATES BY 30/12Z.  THE WRN
   EXTENSION OF THIS BOUNDARY WILL REMAIN QUASI-STATIONARY...STRETCHING
   FROM THE OZARKS WWD TO AN AREA OF LOW PRESSURE OVER WRN OK AT
   30/00Z.  A DRYLINE IS FORECAST TO EXTEND SWD FROM THE LOW PRESSURE
   INTO W-CNTRL TX AND WRN PARTS OF THE EDWARDS PLATEAU REGION AT THIS
   TIME.  MEANWHILE...TROPICAL DEPRESSION BERYL WILL BEGIN TO
   ACCELERATE NEWD FROM S-CNTRL GA THROUGH THE LOWER SAVANNAH RIVER
   VALLEY.
   
   ...NEW ENGLAND INTO THE LOWER GREAT LAKES AND MID-ATLANTIC
   STATES...
   
   AN EXPANSIVE PRE-FRONTAL BAND OF TSTMS IS ONGOING AS OF 12Z FROM
   SWRN ONTARIO/LAKE ERIE SWWD INTO NRN KY...LIKELY FORCED BY THE
   LEADING EDGE OF STRONGER HEIGHT FALLS ASSOCIATED WITH UPPER SYSTEM
   MOVING THROUGH THE GREAT LAKES.  BASED ON SATELLITE
   IMAGERY...DOWNSTREAM AIR MASS ACROSS NY/PA SHOULD EXPERIENCE STRONG
   DAYTIME HEATING.  WHEN COUPLED WITH DEWPOINTS IN THE 60S AND
   MIDLEVEL LAPSE RATES OF AROUND 7 C/KM...ENVIRONMENT WILL BECOME
   MODERATE-STRONGLY UNSTABLE WITH MLCAPE VALUES INCREASING TO
   2000-3000 J/KG.  THIS DESTABILIZATION ALONG WITH THE EWD PROGRESSION
   OF UPPER TROUGH WILL SUPPORT A MARKED INCREASE IN STORM VIGOR AND
   COVERAGE BY EARLY AFTERNOON ALONG COLD FRONT AND/OR LEADING EDGE OF
   COLD POOL ASSOCIATED WITH THE ONGOING STORMS.
   
   THE STRONGEST MID- AND HIGH-LEVEL WIND FIELD ASSOCIATED WITH THE
   TROUGH IS FORECAST TO LAG THE WARM SECTOR TO THE W...LIMITING
   DEEP-LAYER SHEAR MAGNITUDES TO GENERALLY 30-40 KT.  EXPECT THE
   STRONG INSTABILITY TO COMPENSATE WITH ENVIRONMENT BECOMING
   SUPPORTIVE OF MULTIPLE ORGANIZED STORM MODES...INCLUDING BOWING LINE
   SEGMENTS AND SUPERCELLS WITH THE POTENTIAL FOR CORRIDORS OF WIND
   DAMAGE AND SWATHS OF LARGE HAIL.  THE GREATEST RISK FOR A TORNADO OR
   TWO WILL EXIST ALONG WARM FRONT OVER NEW ENGLAND WHERE LOW-LEVEL
   SHEAR WILL BE ENHANCED.
   
   THE SEVERE WEATHER THREAT WILL SPREAD EWD TOWARD THE MID-ATLANTIC
   COAST AND WRN NEW ENGLAND BY LATE AFTERNOON INTO THIS EVENING BEFORE
   GRADUALLY DIMINISHING LATER TONIGHT WITH THE STABILIZATION OF THE
   BOUNDARY LAYER.
   
   ...CNTRL/SRN PLAINS...
   
   AS MENTIONED ABOVE...MIDLEVEL HEIGHTS WILL REBOUND SLIGHTLY TODAY
   WITH PASSAGE OF SYNOPTIC SYSTEM TO THE NE.  AS SUCH...DAYTIME
   HEATING AND LOW-LEVEL CONVERGENCE ALONG STATIONARY FRONT AND DRYLINE
   WILL BE THE PRIMARY MECHANISMS FORCING TSTM DEVELOPMENT THIS
   AFTERNOON.  LATEST CONVECTION-ALLOWING AND MESOSCALE MODEL GUIDANCE
   INDICATE THAT THE HIGHEST PROBABILITY OF STORM INITIATION WILL BE
   ALONG FRONT OVER SRN KS/NRN OK BETWEEN 29/21Z-30/00Z.  OTHER
   ISOLATED STORMS WILL BE POSSIBLE AT THIS TIME SWWD ALONG THE DRYLINE
   INTO W-CNTRL TX.
   
   THE COMBINATION OF STRONG DAYTIME HEATING...BOUNDARY LAYER DEWPOINTS
   IN THE 60S...AND STEEP MIDLEVEL LAPSE RATES ARE EXPECTED TO YIELD A
   MODERATE-STRONGLY UNSTABLE AIR MASS BY MID-LATE AFTERNOON WITH
   MLCAPE VALUES OF 2000-3500 J/KG.  WHEN COUPLED WITH A VERTICALLY
   VEERING WIND PROFILE AND 40-50 KT OF EFFECTIVE BULK SHEAR...SETUP
   WILL BE QUITE FAVORABLE FOR SUPERCELLS CAPABLE OF VERY LARGE HAIL
   AND PERHAPS A COUPLE TORNADOES WITHIN THE FIRST FEW HOURS AFTER
   STORM INITIATION.  WITH TIME...CONVECTION-ALLOWING MODEL GUIDANCE IS
   SUGGESTIVE OF UPSCALE GROWTH INTO A SEWD-MOVING BOW ECHO SYSTEM
   WHICH WOULD SIGNAL A TRANSITION TO A MORE WIDESPREAD DAMAGING WIND
   THREAT ACROSS PORTIONS OF OK...PERHAPS INTO NRN TX TONIGHT.
   
   ...FL/ERN GA/SRN SC...
   
   THE COMBINATION OF A MOIST BOUNDARY LAYER AND BREAKS IN CLOUD COVER
   WILL YIELD POCKETS OF MODEST DESTABILIZATION TODAY INVOF BERYL. 
   GIVEN A STILL MODESTLY STRONG WIND FIELD...A LOW PROBABILITY RISK
   FOR DAMAGING WINDS AND A TORNADO WILL CONTINUE THROUGH THIS
   AFTERNOON.
   
   ..MEAD/ROGERS.. 05/29/2012
   
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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z