Apr 25, 2011 0600 UTC Day 1 Convective Outlook
Updated: Mon Apr 25 06:02:07 UTC 2011
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20110425 1200 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20110425 1200 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
20110425 1200 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
20110425 1200 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 250558
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1258 AM CDT MON APR 25 2011
   
   VALID 251200Z - 261200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS FROM THE ARKLATEX NEWD INTO SRN
   MO...WRN TN AND NWRN MS...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS MUCH OF ERN OK AND TX
   NEWD ACROSS THE LOWER MS INTO THE LOWER OH VALLEYS...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM ERN OH ACROSS MUCH OF PA
   AND NRN SECTIONS OF WV/MD...
   
   ...SYNOPSIS...
   AN ACTIVE SEVERE WEATHER DAY IS LIKELY FROM THE SRN PLAINS INTO THE
   LOWER MS VALLEY AS A POTENT UPPER SHORTWAVE TROUGH DIGS SEWD ACROSS
   THE REGION. ON MON MORNING...LOW PRESSURE IS FORECAST TO BE CENTERED
   ACROSS SRN OK...WITH AN ELONGATED SURFACE TROUGH DEEPENING FROM
   CNTRL TX NEWD INTO MO BY 00Z. STRONG SLY FLOW ACROSS THE WARM SECTOR
   WILL BRING MID TO UPPER 60S F BOUNDARY LAYER DEWPOINTS INTO THE
   ARKLATEX REGION BY 00Z...THEN SPREADING NEWD TOWARDS THE MS RIVER
   DURING THE EVENING. DESPITE MUCH UNCERTAINTY IN REGARD TO EVOLUTION
   OF MULTIPLE AREAS OF CONVECTION THROUGHOUT THE PERIOD...A LARGE AREA
   OF STRONG SHEAR AND INSTABILITY FAVORABLE FOR SUPERCELLS AND
   TORNADOES WILL EXIST ACROSS THE REGION.
   
   ...ERN OK...NERN TX EWD INTO SRN MO...AR...NWRN MS...WRN TN...
   SUBSTANTIAL MORNING CONVECTION...AND ITS EVOLUTION THROUGHOUT THE
   DAY...WILL PLAY A CRUCIAL ROLE IN DEFINING WHERE THE BEST TORNADO
   THREAT WILL BE EXIST. MODELS SUGGEST THAT NUMEROUS THUNDERSTORMS
   WILL BE ONGOING OVER ERN OK INTO AR AND SRN MO...WHERE THEY ARE
   CURRENTLY ONGOING THIS EVENING. THIS SHOULD HELP TO REINFORCE A COLD
   POOL OVER SRN MO/NRN AR. WITH VERY STEEP LAPSE RATES ALOFT AND AMPLE
   EFFECTIVE SHEAR...SOME ELEVATED SEVERE HAIL IS LIKELY WITH THIS
   ACTIVITY.
   
   MEANWHILE...A DRYLINE WILL TAKE SHAPE DURING THE DAY AND WILL MIX
   EWD TO JUST E OF I-35 BY 00Z WHERE IT IS EXPECTED TO STALL. AS MID
   TO UPPER 60S DEWPOINTS STREAM NWD ACROSS TX...THE AIR MASS WILL
   DESTABILIZE QUICKLY...AND SOME STORMS MAY FORM RELATIVELY EARLY OVER
   ERN TX...NRN LA AND MUCH OF AR. ALTHOUGH NOT OPTIMALLY TIMED IN A
   DIURNAL SENSE...SHEAR PROFILES WOULD STILL FAVOR SUPERCELLS WITH THE
   THREAT OF A FEW TORNADOES ALONG WITH HAIL AND WIND.
   
   THE GREATEST SEVERE THREAT IS EXPECTED TO MATERIALIZE BETWEEN 21-00Z
   OVER NERN TX...SPREADING NEWD ACROSS MUCH OF AR AND FAR SRN MO AS
   THE UPPER JET DEVELOPS AND LIFT NEWD. WITH AMPLE MOISTURE AND A 50
   KT LOW LEVEL JET...THERE APPEARS TO BE A SIGNIFICANT THREAT OF
   TORNADOES...A FEW STRONG...AND DAMAGING WINDS. THE EXACT NRN EXTENT
   OF THE STRONG TORNADO THREAT WILL DEPEND ON WHERE THE WARM FRONT/OLD
   CONVECTIVE BOUNDARIES ARE. 
   
   OTHER SUPERCELLS WITH A TORNADO/HAIL THREAT MAY PERSIST ACROSS SRN
   AR...NRN LA...NWRN MS OVERNIGHT IN CLOSER PROXIMITY TO STRONG
   INSTABILITY AND MOISTURE...NEAR THE ENTRANCE REGION OF THE
   DEVELOPING UPPER JET.
   
   ...ERN OH...NRN WV/MD...MUCH OF PA...
   STRONG HEATING WILL OCCUR BENEATH MODERATE SWLY FLOW ALOFT...AND
   CONVERGENCE WILL EXIST NEAR A WARM FRONT/LOW PRESSURE TROUGH
   EXTENDING EWD ACROSS THE OH VALLEY INTO PA/NJ. FORECAST SOUNDINGS
   INDICATE THAT AROUND 1000-1500 J/KG MUCAPE WILL BE PRESENT BY
   AFTERNOON...WITH LITTLE IF ANY CONVECTIVE INHIBITION. A SLY 20-30 KT
   LOW LEVEL JET WILL FURTHER HELP IN THE DESTABILIZATION PROCESS.
   SCATTERED THUNDERSTORMS WILL THUS BE LIKELY.  GIVEN 40-50 KT DEEP
   LAYER SHEAR ACROSS THE AREA...A FEW CELLS WILL BE LONG
   LIVED...POSSIBLY SUPERCELLS...CAPABLE OF LARGE HAIL. DAMAGING WIND
   GUSTS MAY ALSO OCCUR AS STORM MOVE IN EXCESS OF 30 KT WITH STEEP LOW
   LEVEL LAPSE RATES DURING THE PEAK HEATING HOURS.
   
   ..JEWELL.. 04/25/2011
   
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