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

   SPC AC 230559
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1259 AM CDT MON MAR 23 2009
   
   VALID 231200Z - 241200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS LATE THIS AFTERNOON INTO TONIGHT
   FROM NORTH CENTRAL-NERN OK INTO PARTS OF ERN KS...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK AREA
   FROM N TX/OK THROUGH THE CENTRAL PLAINS/WRN MO TO SRN-SERN SD AND
   SWRN MN...
   
   ...SYNOPSIS...
   A DYNAMIC LARGE-SCALE PATTERN WILL EXIST OVER THE CENTRAL CONUS ON
   DAY 1 AS AN INTENSE MID/UPPER-LEVEL LOW SHIFTS NEWD FROM THE CENTRAL
   HIGH PLAINS INTO SD/NEB.  AS THIS PROCESS OCCURS...SIGNIFICANT
   HEIGHT FALLS/DYNAMIC FORCING FOR ASCENT WILL SPREAD ENEWD THROUGH
   THE CENTRAL/SRN PLAINS...AND EVENTUALLY MORE NEWD THROUGH THE
   DAKOTAS INTO UPPER MS VALLEY.  STRONG WSWLY MID AND UPPER LEVEL FLOW
   WILL SPREAD EWD INTO KS/SRN PLAINS BY THIS AFTERNOON...WITH A LEAD
   MID LEVEL JETLET TRACKING NEWD ACROSS NRN KS/NEB WITH THE EJECTING
   UPPER LOW.
   
   IN THE LOW LEVELS...STRONG CYCLOGENESIS IS EXPECTED TO BE UNDERWAY
   ACROSS NERN CO AT 12Z TODAY.  THIS LOW SHOULD UNDERGO SOME DEEPENING
   THIS MORNING AS IT TRACKS NEWD INTO CENTRAL NEB...AND THEN BEGIN TO
   FILL FROM LATE THIS AFTERNOON INTO TONIGHT.  THE LOW IS PROGGED TO
   REACH SERN/ERN SD BY 12Z TUESDAY.  A TRAILING COLD FRONT WILL MOVE
   ENEWD ACROSS NEB/NRN KS DURING THE FIRST HALF OF THE PERIOD. 
   MEANWHILE...A DRY LINE WILL MIX EWD REACHING CENTRAL KS TO WRN OK BY
   EARLY-MID AFTERNOON.  THE AFOREMENTIONED COLD FRONT WILL MOVE ESEWD
   ACROSS KS/SRN HIGH PLAINS FROM LATE AFTERNOON THROUGH TONIGHT...AND
   SHOULD EXTEND FROM WRN IA...WRN MO SWWD THROUGH CENTRAL OK TO SW TX
   BY 12Z TUESDAY.
   
   ...NRN KS/NEB INTO MID MO VALLEY...
   FORCING FOR ASCENT WILL SPREAD NEWD ACROSS THE CENTRAL PLAINS
   ATTENDANT TO A LEAD MID LEVEL IMPULSE ACCOMPANYING THE MID/UPPER
   LEVEL LOW/TROUGH.  SURFACE HEATING IS EXPECTED AHEAD OF THE COLD
   FRONT ACROSS SWRN/SOUTH CENTRAL NEB THIS MORNING INTO THE EARLY
   AFTERNOON.  ALTHOUGH LOW LEVEL MOISTURE WILL BE MODEST /SURFACE
   DEWPOINTS IN THE LOWER 50S...THE SURFACE HEATING COMBINED WITH COLD
   MID LEVEL TEMPERATURES/STEEP LAPSE RATES ATTENDANT TO THE UPPER LOW
   WILL RESULT IN MLCAPE UP TO 500 J/KG.  MODELS SUGGEST INITIAL
   SURFACE BASED STORMS SHOULD DEVELOP BY EARLY AFTERNOON ACROSS
   CENTRAL/SRN NEB AND ADJACENT NRN KS ALONG TRACK OF THE SURFACE LOW. 
   THIS ACTIVITY SHOULD THEN SPREAD ENEWD INTO THE MID MO RIVER VALLEY
   AS DEEP LAYER ASCENT WEAKENS THE CAP OVER THIS REGION AND THE COLD
   FRONT PROGRESSES ENEWD OVERTAKING THE PRE-FRONTAL TROUGH/DRY LINE.  
   
   HAIL/DAMAGING WINDS WILL BE THE PRIMARY SEVERE WEATHER THREATS
   ACROSS THIS REGION.  HOWEVER...THE SETUP WILL BE FAVORABLE FOR
   LOW-TOPPED SUPERCELL DEVELOPMENT ALONG TRACK OF SURFACE LOW WHERE
   ISOLATED TORNADOES ARE POSSIBLE.  RAPIDLY BACKING DEEP-LAYER SHEAR
   VECTORS WITH TIME ACROSS NEB INTO NRN KS SUGGESTS THAT STORMS MAY
   EVOLVE INTO A LINEAR SYSTEM WITH THE THREAT FOR HAIL AND DAMAGING
   WINDS CONTINUING EWD THROUGH THE MID AND LOWER MO VALLEYS MONDAY
   NIGHT.
   
   ...CENTRAL KS/WRN MO SSWWD TO OK/RED RIVER VALLEY...
   A CAP EXTENDING FROM CENTRAL/SRN KS SWD THROUGH THE RED RIVER VALLEY
   IS EXPECTED TO LIMIT TSTM DEVELOPMENT UNTIL MID-LATE AFTERNOON. 
   INITIAL ACTIVITY SHOULD OCCUR ACROSS CENTRAL/SRN KS BETWEEN 21-00Z
   AS THE COLD FRONT BEGINS TO MERGE WITH THE DRY LINE...AND FORCING
   FOR ASCENT SPREADS EWD INTO SRN KS/OK ATTENDANT TO A SECOND LOBE OF
   VORTICITY/FORCING FOR ASCENT WITHIN LEFT EXIT REGION OF MID/UPPER
   LEVEL JETS.  ADDITIONAL DEVELOPMENT WILL TAKE PLACE WITH SWD EXTENT
   INTO NRN OK BY 00Z AS THE COLD FRONT CONTINUES TO OVERTAKE THE DRY
   LINE...WITH TSTMS EXPECTED TO DEVELOP INTO WRN MO MONDAY EVENING AND
   SWD TO THE RED RIVER LATE IN THE PERIOD.  
   
   THE QUALITY OF MOISTURE RETURN...EVEN INTO THIS REGION...SHOULD
   REMAIN MODEST WITH SURFACE DEWPOINTS EXPECTED TO BE IN THE MID-UPPER
   50S.  THIS COMBINED WITH SURFACE HEATING AND STEEP MID LEVEL LAPSE
   RATES REACHING THIS AREA BY LATE AFTERNOON WILL RESULT IN MLCAPE UP
   TO 1000 J/KG FROM SRN KS INTO CENTRAL OK.  THE ORIENTATION OF DEEP
   LAYER SHEAR VECTORS MORE NORMAL TO THE SURFACE BOUNDARIES SUGGEST
   THE POTENTIAL FOR BROKEN LINE SEGMENTS OR DISCRETE STORMS FROM THIS
   AFTERNOON INTO TONIGHT.  STRONG FLOW ALOFT WILL PROMOTE FAST STORM
   MOTIONS /NEWD AT 40-50 KT/.  STRONG SLY LLJ /50+ KT/ EXTENDING NWD
   FROM OK WITH FURTHER STRENGTHENING TONIGHT WILL PROMOTE LARGE CURVED
   HODOGRAPHS AND SUPPORT A THREAT FOR TORNADOES...SOME STRONG /IN THE
   MODERATE RISK AREA/.  HAIL AND DAMAGING WINDS WILL ALSO ACCOMPANY
   THE SEVERE THREAT ACROSS THIS PORTION OF THE SLIGHT RISK AND
   MODERATE RISK AREAS.
   
   ..PETERS/GARNER.. 03/23/2009
   
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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z