May 23, 2007 1300 UTC Day 1 Convective Outlook
Updated: Wed May 23 12:50:41 UTC 2007
Probabilistic to Categorical Outlook Conversion Table (Effective Feb 14, 2006).
Categorical Graphic
20070523 1300 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20070523 1300 UTC Day 1 Tornado Probabilities Graphic
Probabilistic Damaging Wind Graphic
20070523 1300 UTC Day 1 Damaging Wind Probabilities Graphic
Probabilistic Large Hail Graphic
20070523 1300 UTC Day 1 Large Hail Probabilities Graphic
   SPC AC 231247
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0747 AM CDT WED MAY 23 2007
   
   VALID 231300Z - 241200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON INTO TONIGHT FOR
   THE NE TX PANHANDLE...NW OK...AND SRN KS...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK...FROM
   THE SRN HIGH PLAINS TO THE MID MO VALLEY...
   
   ...SYNOPSIS...
   AN INITIAL SHORTWAVE TROUGH OVER THE WRN DAKOTAS WILL LIFT NEWD OVER
   MANITOBA AS AN UPSTREAM TROUGH OVER SRN UT/NRN AZ MOVES EWD TO NRN
   NM/SRN CO THIS EVENING AND THEN WRN KS LATE TONIGHT.  AT THE
   SURFACE...A COLD FRONT WILL SLOW ITS SEWD MOVEMENT ACROSS SRN KS/NW
   OK/TX PANHANDLE THIS MORNING...AND STALL BY EARLY AFTERNOON.  THE
   FRONT WILL THEN BEGIN A SLOW RETREAT TO THE N THIS AFTERNOON/EVENING
   IN RESPONSE TO CYCLOGENESIS OVER THE HIGH PLAINS IN ADVANCE OF THE
   GREAT BASIN SHORTWAVE TROUGH.  THIS SURFACE LOW WILL THEN DEVELOP
   NEWD INTO NRN KS ALONG THE BAROCLINIC ZONE DURING THE OVERNIGHT
   HOURS.  THE PRIMARY SEVERE STORM THREAT AREAS SHOULD BE ENE OF THE
   DEVELOPING SURFACE LOW ALONG THE RETREATING SURFACE FRONT LATE THIS
   AFTERNOON...AND TO THE W ACROSS THE HIGH PLAINS WITH THE EJECTING
   MID LEVEL WAVE BY EARLY TONIGHT.
   
   ...NRN TX PANHANDLE/NW OK/SRN KS THIS AFTERNOON INTO TONIGHT...
   THE PRIMARY UNCERTAINTIES THIS AREA WILL BE THE EVENTUAL LOCATION OF
   THE SURFACE FRONT BY THIS AFTERNOON...AND THE COVERAGE OF CONVECTION
   ALONG THE BOUNDARY BY THIS EVENING.  SURFACE OBSERVATIONS SHOW THAT
   THE COLD FRONT IS A LITTLE FARTHER SE THAN THE MOST AGGRESSIVE MODEL
   FORECASTS...THOUGH OBSERVATIONAL TRENDS OVER THE PAST 2-3 HOURS
   SUGGEST THAT MOTION OF THE FRONT HAS SLOWED SUBSTANTIALLY.  THERE
   ARE ALSO SOME DISCREPANCIES IN HOW QUICKLY THE BOUNDARY RETREATS
   LATER TODAY INTO EARLY TONIGHT...WHILE ALMOST ALL MODELS BUT THE 4
   KM WRF NMM GENERATE CONVECTION ALONG THE RETREATING FRONT LATE THIS
   AFTERNOON.
   
   REGIONAL SOUNDINGS AND SURFACE OBSERVATIONS IN THE WARM SECTOR SHOW
   BOUNDARY LAYER DEWPOINTS OF 64-67 F NEAR AND JUST UPSTREAM FROM THE
   MDT RISK AREA.  WITH THIS MOISTURE COMES THE POSSIBILITY OF STRATUS
   LINGERING INTO THE AFTERNOON ACROSS MUCH OF THE WARM SECTOR...WHICH
   MAY DELAY SURFACE HEATING.  STILL...AFTERNOON TEMPERATURES IN THE
   MID-UPPER 70S WITH MID 60S DEWPOINTS...BENEATH MODEST MID LEVEL
   LAPSE RATES...SHOULD RESULT IN MLCAPE VALUES OF 2000-2500 J/KG ALONG
   THE SURFACE BOUNDARY BY MID-LATE AFTERNOON.  MODEL FORECAST
   SOUNDINGS...AS WELL AS MODIFIED 12Z SOUNDINGS... SUGGEST THAT SOME
   CONVECTIVE INHIBITION WILL PERSIST OVER MUCH OF THE WARM SECTOR. 
   GIVEN THAT THE STRONGER LARGE SCALE FORCING FOR ASCENT WILL REMAIN
   FARTHER W/NW ACROSS NRN NM AND SRN CO...LOW-LEVEL ASCENT ALONG THE
   RETREATING FRONT WILL BE NECESSARY FOR STORM INITIATION LATER THIS
   AFTERNOON.  THE MOST PROBABLE AREA FOR STORM DEVELOPMENT WILL BE
   IMMEDIATELY ENE OF THE SURFACE TRIPLE POINT IN THE TX PANHANDLE
   AFTER 21Z...WITH CONVECTION EXPECTED TO DEVELOP ENEWD ALONG THE
   FRONT INTO NW OK AND SW KS.
   
   A GRADUAL INCREASE IN MID-UPPER LEVEL SWLY FLOW AND BACKING/
   STRENGTHENING LOW-LEVEL FLOW DURING THE EVENING WILL CONTRIBUTE TO
   AN INCREASINGLY FAVORABLE ENVIRONMENT FOR SUPERCELLS FROM ABOUT
   21-03Z.  EXPECT STORMS TO MOVE ALONG THE BOUNDARY DURING THE
   EVENING...WITH THE POTENTIAL TO PRODUCE TORNADOES...VERY LARGE
   HAIL...AND DAMAGING WINDS.  A COUPLE OF STRONG TORNADOES MAY OCCUR
   THIS EVENING GIVEN THE EXPECTED MAGNITUDE OF THE LOW-LEVEL SHEAR
   WITH AT LEAST MID 60S BOUNDARY LAYER DEWPOINTS.
   
   ...NE NM/SE CO INTO WRN KS THIS EVENING INTO TONIGHT...
   IN ASSOCIATION WITH THE EJECTING MID LEVEL WAVE AND DEVELOPING
   SURFACE CYCLONE...FORCING FOR ASCENT WILL INCREASE OVER THE HIGH
   PLAINS THIS EVENING INTO TONIGHT.  AT THE SAME TIME...MOISTURE WILL
   ATTEMPT TO SPREAD BACK TO THE W/NW.  INSTABILITY WILL LIKELY REMAIN
   FAIRLY LIMITED OVER THE HIGH PLAINS...BUT STRONG ASCENT AND VERTICAL
   SHEAR WILL BOTH HELP COMPENSATE AND SUPPORT A LARGE CONVECTIVE
   CLUSTER BEGINNING LATE THIS AFTERNOON IN NM/CO...AND CONTINUING INTO
   WRN KS TONIGHT.  A MIXTURE OF BOWING SEGMENTS AND EMBEDDED
   SUPERCELLS CAN BE EXPECTED WITHIN THE LARGER MCS...AND THE STRONGER
   STORMS COULD PRODUCE LARGE HAIL..DAMAGING WINDS...AND PERHAPS A
   TORNADO OR TWO.
   
   ..THOMPSON/GRAMS.. 05/23/2007
   
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