May 10, 2013 1300 UTC Day 1 Convective Outlook
Updated: Fri May 10 12:50:36 UTC 2013
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20130510 1300 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20130510 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
20130510 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
20130510 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.
Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 184,447 29,448,396 Houston, TX...San Antonio, TX...Austin, TX...Columbus, OH...New Orleans, LA...
   SPC AC 101247
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0747 AM CDT FRI MAY 10 2013
   
   VALID 101300Z - 111200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF CNTRL AND SRN TX
   TO THE CNTRL GULF COAST...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE UPPER OH VALLEY INTO
   MID ATLANTIC STATES...
   
   ...SYNOPSIS...
   
   A SPLIT FLOW REGIME WILL PERSIST THROUGH THE D1 PERIOD...FEATURING
   AN EVOLVING LARGE-SCALE TROUGH OVER THE CNTRL AND ERN CONUS INTO NRN
   MEXICO...AND AN AMPLIFIED RIDGE FROM THE FAR ERN PACIFIC THROUGH THE
   PACIFIC NW INTO WRN CANADA.  WITHIN THIS BROAD-SCALE PATTERN...MID
   AND UPPER-LEVEL JET STREAKS DEVELOPING EQUATORWARD FROM THE CANADIAN
   PRAIRIE PROVINCES INTO THE NRN PLAINS AND UPPER MS VALLEY WILL
   CONTRIBUTE TO SIGNIFICANT INTENSIFICATION OF A POLAR-BRANCH TROUGH
   OVER ONTARIO INTO THE UPPER GREAT LAKES.  THIS SYSTEM WILL BE
   PRECEDED BY A WEAKER SHORT-WAVE TROUGH WHICH WILL PROGRESS EWD
   ACROSS THE GREAT LAKES AND OH VALLEY.  MEANWHILE...A SUBTROPICAL JET
   STREAK WILL BE MAINTAINED FROM THE DOWNSTREAM SIDE OF A POSITIVELY
   TILTED TROUGH OVER THE SRN ROCKIES INTO NWRN MEXICO EWD ACROSS THE
   S-CNTRL AND SERN CONUS.  A SERIES OF VORTICITY MAXIMA ARE FORECAST
   TO EMERGE FROM THIS TROUGH AND TRANSLATE EWD WITHIN THIS
   HIGH-MOMENTUM AIR STREAM...AFFECTING TX AND THE GULF COAST STATES.
   
   IN THE LOW LEVELS...A COLD FRONT ASSOCIATED WITH THE
   LEAD...POLAR-BRANCH SHORT-WAVE TROUGH WILL ADVANCE EWD THROUGH THE
   OH VALLEY AND LOWER GREAT LAKES REGION...TRAILING A DEEPENING
   SURFACE LOW WHICH WILL TRACK FROM SRN LOWER MI NEWD INTO SRN QUEBEC
   BY 11/12Z.  THE SWRN EXTENSION OF THE COLD FRONT WILL PROGRESS SEWD
   THROUGH THE OZARK PLATEAU...AND ACROSS MUCH OF THE SRN PLAINS...AND
   INTO THE LOWER MS VALLEY.  THIS COLD FRONT AND PRE-EXISTING OUTFLOW
   BOUNDARIES WILL SERVE AS THE PRIMARY FOCI FOR STRONG TO SEVERE
   STORMS TODAY INTO TONIGHT.
   
   ...TX TODAY INTO TONIGHT...
   
   A SMALL CLUSTER OF STORMS WHICH EVOLVED EARLY THIS MORNING WAS
   LOCATED JUST W/SW OF SAT AS OF 12Z.  BASED ON 12Z OBSERVED
   SOUNDINGS...THIS ACTIVITY IS LIKELY SLIGHTLY ELEVATED AND ROOTED
   WITHIN A STEEP LAPSE RATE ENVIRONMENT ABOVE THE CAP.  DAYTIME
   HEATING COUPLED WITH A MOISTENING PBL ALONG AND SOUTH OF A
   RETREATING OUTFLOW BOUNDARY WILL RESULT IN THESE STORMS BECOMING
   PROGRESSIVELY SURFACE-BASED BY MID TO LATE MORNING AS THEY APPROACH
   THE MIDDLE AND UPPER TX COAST.  HERE...THE 12Z OBSERVED SOUNDING
   DATA INDICATE THE POTENTIAL FOR MODERATE AFTERNOON INSTABILITY WITH
   MLCAPE VALUES APPROACHING 1500-2500 J/KG.  GIVEN AROUND 50 KT OF
   DEEP-LAYER SHEAR...THE POTENTIAL WILL EXIST FOR SUPERCELLS AND
   BOWING STRUCTURES CAPABLE OF LARGE HAIL AND DAMAGING WINDS.
   
   ADDITIONAL STORM DEVELOPMENT WILL BE POSSIBLE THIS AFTERNOON INTO
   EVENING FROM THE VICINITY OF THE COLD FRONT OVER WRN PARTS OF THE
   EDWARDS PLATEAU SEWD ALONG AN OUTFLOW BOUNDARY INTO THE TX BRUSH
   COUNTRY.  HERE TOO...THE ENVIRONMENT WILL BE SUPPORTIVE OF ORGANIZED
   STORM MODES /INCLUDING SUPERCELLS/ CAPABLE OF LARGE HAIL AND
   DAMAGING WINDS.
   
   ...LOWER MS VALLEY TODAY...
   
   A LONG-LIVED QLCS WILL CONTINUE ESEWD THROUGH THE REMAINING PARTS OF
   SERN LA/MS WHERE A VERY MOIST PBL WITH DEWPOINTS OF AROUND 70 F ARE
   YIELDING MLCAPE VALUES OF 500-1000 J/KG.  GIVEN 60 KT OF EFFECTIVE
   BULK SHEAR AND EFFECTIVE SRH VALUES OF AROUND 200 M2/S2 --PER 12Z
   LIX SOUNDING...THE SETUP WILL REMAIN SUPPORTIVE OF EMBEDDED LEWP
   STRUCTURES CAPABLE OF DAMAGING WINDS...HAIL...AND PERHAPS A TORNADO.
   THIS THREAT MAY DEVELOP INTO SWRN AL /AND PERHAPS THE WRN FL PNHDL/
   LATER THIS MORNING BEFORE DIMINISHING AS THE CONVECTIVE SYSTEM
   ENCOUNTERS AN INCREASINGLY DRY AND MORE STABLE AIR MASS.
   
   FOR ADDITIONAL NEAR-TERM GUIDANCE...SEE WW 154 AND MCD 620.
   
   ...UPPER OH VALLEY INTO THE MID ATLANTIC STATES THIS AFTERNOON AND
   EVENING...
   
   LATEST MODEL GUIDANCE SUGGESTS THAT A VORTICITY MAXIMUM CURRENTLY
   OVER WRN TN WILL ACCELERATE NEWD INTO THE REGION TODAY...AHEAD OF
   THE LEAD...POLAR-BRANCH SHORT-WAVE TROUGH.  A CORRESPONDING
   ENHANCEMENT IN FORCING FOR ASCENT AND VERTICAL SHEAR WILL GIVE RISE
   TO WIDELY SCATTERED STRONG TO SEVERE TSTMS ALONG AND AHEAD OF THE
   COLD FRONT WITHIN A MODERATELY UNSTABLE ENVIRONMENT WITH MLCAPE
   APPROACHING 1000-1500 J/KG.  UPSCALE GROWTH OF STORMS INTO BOWING
   LINE SEGMENTS IS POSSIBLE WITH THE PRIMARY HAZARDS BEING DAMAGING
   WINDS AND SOME HAIL.
   
   ...FL THIS AFTERNOON...
   
   LATEST CONVECTION-ALLOWING MODEL GUIDANCE IS IN GOOD AGREEMENT IN
   SUGGESTING THE DEVELOPMENT OF TSTMS THIS AFTERNOON OVER THE CNTRL
   PENINSULA WITH STORMS SUBSEQUENTLY MOVING OFF THE E-CNTRL AND SERN
   COAST LATE THIS AFTERNOON INTO EVENING.  THE COMBINATION OF MODERATE
   INSTABILITY...RELATIVELY COOL MIDLEVEL TEMPERATURES...AND MODEST
   DEEP-LAYER SHEAR WILL BE SUPPORTIVE OF ISOLATED SEVERE STORMS
   CAPABLE OF MARGINALLY SEVERE HAIL AND LOCALLY DAMAGING WIND GUSTS.
   
   ..MEAD/DEAN.. 05/10/2013
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z