Categorical Graphic
Probabilistic Tornado Graphic
Probabilistic Damaging Wind Graphic
Probabilistic Large Hail Graphic

   SPC AC 220552
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1252 AM CDT THU MAY 22 2008
   
   VALID 221200Z - 231200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS PORTIONS SWRN NEB...WRN
   KS...EXTREME NWRN OK...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ELSEWHERE FROM WRN NEB AND
   EXTREME SERN WY TO PORTIONS NW TX/SW OK...
   
   ...SYNOPSIS...
   PRIMARY UPPER AIR FEATURE FOR THIS OUTLOOK WILL BE DEEP/LARGE
   CYCLONE -- NOW DEVELOPING ACROSS GREAT BASIN FROM HIGH-AMPLITUDE
   SYNOPTIC TROUGH.  LATEST 00Z 250 MB ANALYSIS SHOWED 150 KT JET MAX
   DIGGING SSEWD ALONG W SIDE OF THIS SYSTEM...ACROSS ORE...NERN CA AND
   WRN NV.  AS SEVERAL RELATIVELY LOW-AMPLITUDE VORTICITY LOBES REVOLVE
   AROUND THIS GYRE...MEAN CIRCULATION CENTER SHOULD RETROGRADE ACROSS
   SRN GREAT BASIN DURING THIS PERIOD.
   
   AS THIS OCCURS...ELONGATED LOW PRESSURE ZONE -- PERHAPS WITH TWO OR
   THREE LOCALIZED ISOBARIC MINIMA -- SHOULD DEVELOP ALONG SFC
   BAROCLINIC ZONE FROM S-CENTRAL/SERN WY SEWD ACROSS NERN CO TO NWRN
   KS.  AFTERNOON DRYLINE WILL INTERSECT FRONT/LOW INVOF WRN PORTIONS
   KS/NEB BORDER...AND EXTEND SWD ACROSS WRN KS...CENTRAL/ERN PORTIONS
   TX/OK PANHANDLES...AND W-CENTRAL TX...WITH SLGT EWD MIXING EARLY-MID
   AFTERNOON AND RETREAT BEGINNING BEFORE SUNSET.  SHORT/BENT-BACK
   DRYLINE SEGMENT MAY ARC NWWD ACROSS PORTIONS NWRN KS/SERN NEB/NERN
   CO...PERMITTING NARROW CORRIDOR OF FAVORABLE MOISTURE ALONG WARM
   FRONTAL ZONE OVER THOSE AREAS.  FRONT IS FCST TO EXTEND FROM LOW
   ESEWD ACROSS NERN KS AND W-CENTRAL/SWRN MO...WITH NET NWD DRIFT
   THROUGHOUT PERIOD.
   
   ...CENTRAL/SRN HIGH PLAINS...
   ANOTHER AMONG SEVERAL CONSECUTIVE DAYS OF SVR POTENTIAL IS EXPECTED
   ACROSS HIGH PLAINS...WITH REGIONAL OUTBREAK OF LARGE HAIL AND
   TORNADOES BEING MOST PROBABLE ACROSS CATEGORICAL MDT RISK AREA. 
   CLIMATOLOGICALLY FAVORABLE REGIME WILL FEATURE DIURNALLY SLOSHING
   DRYLINE...LOCATED BENEATH FAVORABLE SHEAR AND MOISTURE PROFILES...E
   OF LARGE UPPER LEVEL LOW.  SVR CONVECTION TODAY IS FCST TO BE MUCH
   BETTER ORGANIZED AND POTENTIALLY MORE DANGEROUS THAN ON WEDNESDAY
   THANKS TO GREATER MOISTURE...STRONGER DEEP-LAYER SHEAR AND MORE
   INTENSE LOW LEVEL FOCI FOR ASCENT.
   
   THERMODYNAMIC PROFILES WILL BE FAVORABLE WITH STG SFC HEATING IN
   RICHLY MOIST AIR MASS...BETWEEN DRYLINE AND WARM FRONT.  PRECURSORY
   MOIST ADVECTION -- NOW WELL UNDERWAY -- SHOULD RESULT IN SFC DEW
   POINTS UPPER 50S TO LOW 60S IN IMMEDIATE VICINITY
   DRYLINE...INCREASING QUICKLY TO MID 60S EWD OVER MUCH OF CENTRAL/NRN
   KS...AND UPPER 60S/LOW 70S OVER TX/OK MOIST SECTOR.  BY MID
   AFTERNOON...EXPECT POTENTIAL FOR SFC-BASED TSTMS TO DEVELOP INVOF
   ELONGATED SFC LOW AND NEARBY DRYLINE AND WARM FRONTAL SEGMENTS. 
   THIS ACTIVITY SHOULD MOVE NNEWD TO NNWWD ACROSS WARM FRONTAL ZONE. 
   BECAUSE OF RELATIVELY BACKED FLOW INVOF WARM FRONT...EFFECTIVE BULK
   SHEAR...LOW LEVEL SRH AND BOUNDARY LAYER VORTICITY EACH WILL BE
   MAXIMIZED THERE...AND ANY MATURE STORMS INTERACTING WITH FRONTAL
   ZONE MAY PRODUCE TORNADOES BUT THEN MOVE QUICKLY INTO UNFAVORABLE
   SFC AIR MASS.
   
   VERTICAL SHEAR INCREASINGLY WILL FAVOR SUPERCELLS/TORNADOES FARTHER
   S IN WRN PORTION OF MOIST SECTOR WITH TIME AS WELL...AS CAPPING
   WEAKENS ALONG DRYLINE.  THIS ESPECIALLY IS A CONCERN LATE AFTERNOON
   INTO EARLY EVENING WHEN LIFTED PARCELS STILL ARE SFC-BASED AND
   STRENGTHENING LLJ GREATLY ENLARGES HODOGRAPHS IN ENVIRONMENT OF ANY
   EXISTING SUPERCELLS.  POTENTIAL WILL BUILD SWD ALONG KS SEGMENT OF
   DRYLINE THROUGH AFTERNOON.
   
   STRONG MERIDIONAL COMPONENT OF MEAN FLOW AND POTENTIAL FOR
   SCATTERED-NUMEROUS TSTM COVERAGE PROVIDES SOME STORM-SCALE
   UNCERTAINTIES PRECLUDING GREATER SIGNIFICANT HAIL/TORNADO
   PROBABILITIES ATTM.  HOWEVER...THERE SHOULD BE SUFFICIENT SBCINH --
   E.G. 2000-2500 J/KG OVER MUCH OF WRN KS AND PERHAPS SMALL PART OF
   SWRN NEB -- TO SUPPORT POTENTIAL FOR SEVERAL
   DISCRETE/CYCLIC/TORNADIC SUPERCELLS DURING AFTERNOON AND EARLY
   EVENING HOURS...ALSO PRODUCING DESTRUCTIVE HAIL.  THOUGH
   SUPERCELLS/TORNADO POTENTIAL MAY PERSIST WELL INTO NIGHTTIME
   HOURS...OVERALL MODE SHOULD BECOME MORE LINEAR WITH TIME AFTER DARK.
    INCREASING/ELEVATED TSTM COVERAGE WELL N OF WARM FRONT -- ACROSS
   N-CENTRAL PLAINS...WILL RESULT IN POTENTIAL FOR SVR HAIL AS FAR N AS
   PORTIONS SD.
   
   ...SRN HIGH PLAINS...
   STRONGER BUOYANCY -- E.G. 3000-4000 J/KG MLCAPE -- AND GREATER
   MLCINH EACH ARE FCST SWD OVER ERN PANHANDLES AND WRN OK...COMPARED
   TO FARTHER N...LIMITING POTENTIAL COVERAGE.  THREAT THEREFORE
   BECOMES MORE ISOLATED AND CONDITIONAL WITH SWD EXTENT ACROSS SRN
   HIGH PLAINS...HENCE SWD REDUCTION IN SVR PROBABILITIES. 
   HOWEVER...VERY LARGE HAIL AND PERHAPS A FEW TORNADOES WILL BE
   POSSIBLE WITH ANY STORMS THAT CAN FORM OVER THIS AREA.  SOME FCST
   SOUNDINGS REASONABLY INDICATE SLGT INCREASE IN BULK SHEAR -- E.G.
   55-60 KT OVER WRN OK OR ABOUT 5-10 KT MORE THAN S OF WARM FRONT IN
   KS -- THANKS TO MORE WLY COMPONENT OF FLOW ALOFT.
   
   ...ARKLATEX AREA...ERN OK...
   SCATTERED TSTMS ARE EXPECTED TO DEVELOP THIS AFTERNOON IN ZONE OF
   WEAK LARGE SCALE ASCENT/DESTABILIZATION ALOFT...JUXTAPOSED WITH STG
   DIURNAL HEATING...RICH BOUNDARY LAYER MOISTURE...AND RELATIVELY WEAK
   SBCINH.  MAIN LIMITING FACTOR WILL BE LACK OF SUBSTANTIAL LOW LEVEL
   FOCI...ESPECIALLY PRIOR TO DEVELOPMENT OF ANY OUTFLOW BOUNDARIES. 
   FCST SOUNDINGS INDICATE ENLARGED LOW LEVEL HODOGRAPHS...ESPECIALLY
   IN NARROW ZONE OF SELY SFC WINDS IMMEDIATELY AHEAD OF UPPER LOW AND
   S OF WARM FRONTAL ZONE.  ALTHOUGH MID-UPPER LEVEL FLOW SHOULD BE
   RELATIVELY WEAK...MESSY/TEMPORARY SUPERCELL ORGANIZATION IS POSSIBLE
   AMONG MORE PREDOMINANT MULTICELLULAR MODES.  THEREFORE WILL INCLUDE
   MRGL PROBABILITIES FOR HAIL AND DAMAGING CONVECTIVE GUSTS.
   
   ..EDWARDS/SMITH.. 05/22/2008
   
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