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May- 4-2003 1300 UTC Day 1 Convective Outlook
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   STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK 
   DAY 1 CONVECTIVE OUTLOOK...REF AWIPS GRAPHIC PGWE46 KWNS.
   
   VALID 041300Z - 051200Z
   
   THERE IS A HIGH RISK OF SVR TSTMS THIS AFTERNOON AND EARLY EVENING
   OVER PORTIONS ERN KS...ERN OK...WRN MO...AND WNR AR...TO THE RIGHT
   OF A LINE FROM MLC 35 WSW JLN 30 WNW FLV STJ P35 IRK JEF TBN HOT 
   30 NW PRX MLC.
   
   THERE IS A MDT RISK OF SVR TSTMS ELSEWHERE ACROSS ERN KS...ERN
   OK...AR...MO...SERN NEB...SRN IA...EXTREME WRN IL...AND NERN TX...
   TO THE RIGHT OF A LINE FROM 40 S DAL DAL DUA TUL 20 E EMP 25 NE MHK
   BIE OMA 45 WSW DSM OTM 30 ESE BRL SPI 25 SE BLV 25 ESE POF PBF GGG
   45 SW TYR 40 S DAL.
   
   THERE IS A SLGT RISK OF SVR TSTMS ELSEWHERE TO THE RIGHT OF A LINE
   FROM 20 N MWL 35 NW ADM 40 NNW BVO CNK 25 SSW MHN AIA 35 N CDR PHP
   30 W BKX RST JVL 45 NE LAF 40 WSW LUK LOZ RMG CBM MLU 50 SW LFK
   HDO 55 NNE DRT 15 WNW BWD 20 N MWL.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 10 WSW GLS COT
   45 NW DRT 40 S OKC PNC ICT 35 NW HUT 25 N DDC 45 ESE GLD IML
   35 NNW AKO 25 SE FCL 45 W COS DRO PGA P38 75 SSW ELY 4LW 20 E PDX
   25 ENE BLI 35 NNW 63S 55 NNW FCA 55 ENE CTB 55 N GGW 65 NE MOT
   45 SW DVL 15 E JMS BRD 40 S DLH IMT 40 SE OSC 40 SE DTW DOV
   25 S EWN ...CONT... 25 E CHS 15 S AUO 45 NNW MOB 35 WNW LFT
   30 ESE BPT.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 20 SSE SRQ
   10 NNW VRB.
   
   --- SYNOPSIS ---
   PROGRESSIVE MID-UPPER LEVEL PATTERN CONTINUES TODAY...MAIN LARGE-
   SCALE FEATURE BEING WRN CONUS TROUGH.  ASSOCIATED CYCLONE -- NOW
   EVIDENT ON MOISTURE CHANNEL IMAGERY OVER ERN WY/ERN MT...IS
   EXPECTED TO DRIFT EWD ACROSS WRN DAKOTAS...WHILE STRONG SPEED MAX
   AND SHORTWAVE TROUGH NOW EVIDENT OVER WRN CO MOVE EWD ACROSS
   KS/NEB.  UPSTREAM....STRONG SHORTWAVE TROUGH NOW MOVING ASHORE
   WA/ORE SHOULD SHIFT ESEWD THROUGH AFTERNOON.  
   
   AT SURFACE...LARGE OUTFLOW POOL FROM NEB MCS HAS EFFECTIVELY
   BIFURCATED SURFACE CYCLONE...BUT LOW SHOULD CONSOLIDATE AGAIN OVER
   SRN NEB/NRN KS DURING DAY AND MOVE EWD THEN NEWD INTO WRN IA BY
   00Z.  DRYLINE -- NOW ANALYZED FROM W-CENTRAL KS SWD ACROSS ERN
   PORTIONS OK/TX PANHANDLES THEN SWWD TO PERMIAN BASIN REGION...
   SHOULD ADVECT AND MIX EWD THROUGHOUT REMAINDER MORNING/
   AFTERNOON...REACHING ERN PORTIONS KS/OK BY LATE AFTERNOON WHEN
   INITIATION OF MOST INTENSE CONVECTION IS FORECAST.  WARM FRONT --
   NOW ANALYZED FROM CENTRAL KS/NEB BORDER REGION SEWD ACROSS S-
   CENTRAL AR TO WRN FL PANHANDLE -- SHOULD LIFT NWD RAPIDLY ACROSS
   NERN KS...REMAINDER AR AND MO TODAY AND ACROSS PORTIONS WRN IL
   TONIGHT.  
   
   --- LOWER MO/MID MS VALLEY REGIONS TO ARKLATEX ---
   SIGNIFICANT SEVERE TSTM EVENT LIKELY...WITH OUTBREAK OF
   TORNADOES...LARGE HAIL AND DAMAGING WIND ANTICIPATED TODAY FROM
   MUCH OF ERN KS/ERN OK AND MO SWWD AT LEAST AS FAR AS SE OK/NE
   TX...SHIFTING EWD WITH TIME ACROSS MO/AR/WRN IL.  POTENTIAL EXISTS
   FOR LONG-TRACK AND VIOLENT TORNADOES WITH A FEW SUPERCELLS IN HIGH
   RISK AREA...AND SEVERAL CYCLIC/MULTIPLE TORNADO PRODUCING STORMS
   SHOULD OCCUR.  NUMEROUS EVENTS OF DAMAGING GUSTS/HAIL ARE POSSIBLE
   WITH THESE STORMS...AS WELL AS WIND DAMAGE FROM LATER BOWS/LEWPS
   THAT MAY EVOLVE FROM EARLY SUPERCELLS.
   
   SPORADIC AND MAINLY MARGINAL SEVERE HAIL IS POSSIBLE THIS MORNING
   FROM BAND OF TSTMS -- IN STRONG WAA/ISENTROPIC ASCENT REGIME NOW
   MAXIMIZED FROM SERN MO TO SWRN SD AND FCST TO WEAKEN AS IT MOVES
   EWD/NEWD.  SUBSEQUENTLY...MAIN SEVERE THREAT WILL BE FROM THIS
   AFTERNOON THROUGH AT LEAST 6Z OVER E-CENTRAL PLAINS/LOWER MO VALLEY
   AND INTO ARKLATEX AREA.  CAP SHOULD BREAK ALONG DRYLINE FRONT
   THROUGHOUT AFTERNOON IN DISCRETE CELLS...RESULTING IN RAPID
   DEVELOPMENT OF TSTMS IN A SWEEPING ARC OVER WRN PORTIONS SLGT/MDT
   CATEGORICAL RISK AREAS.  UNUSUALLY INTENSE UPDRAFT ACCELERATIONS
   AND RAPID EVOLUTION TO SUPERCELLS IS ANTICIPATED GIVEN STRENGTH OF
   BOTH INSTABILITY AND ENVIRONMENTAL KINEMATIC FIELDS.
    
   BY EARLY AFTERNOON...AIR MASS OVER THAT PORTION OF THIS REGION N OF
   MO RIVER WILL HAVE HAD SUFFICIENT TIME TO HEAT/DESTABILIZE AFTER
   MORNING CONVECTION...THROUGH BOTH WAA AND SURFACE INSOLATION. 
   FARTHER S ACROSS ERN OK...WRN AR...AND NE TX...LOW LEVEL AIR MASS
   IS UNCONTAMINATED BY PRIOR CONVECTIVE STABILIZATION AND SHOULD
   BECOME VERY UNSTABLE THROUGH THIS AFTERNOON BEHIND WARM FROPA. 
   MODIFIED RAOBS AND RUC SOUNDINGS SUGGEST MLCAPE RANGING FROM ALMOST
   4000 J/KG OVER ARKLATEX TO 2000 J/KG IN MO/NEB BORDER REGION. 
   STRONG VERTICAL SHEAR FORECAST THROUGHOUT REGION...E.G. 60-80 KT 0-
   6 KM VECTOR SHEAR AND 90-120 KT BRN SHEARS.  LARGE HODOGRAPHS
   FORECAST WITH 0-1 KM SRH 200-400 J/KG...AND 0-3 KM SRH 300-600 J/KG
   ALONG AND S OF WARM FRONT OVER MDT/HIGH RISK AREAS.  SEVERE TSTMS
   MAY BACKBUILD SWWD INTO PORTIONS CENTRAL/SRN TX...OUTLOOK BEING
   MORE CONDITIONAL IN THIS REGION BECAUSE OF CAPPING.  HOWEVER...VERY
   LARGE HAIL...WIND DAMAGE AND SLGT TORNADO RISK EXIST WITH ANY TSTMS
   WHICH DEVELOP IN THAT AREA.
   
   --- NRN/CENTRAL PLAINS ---
   EXPECT LESS AIR MASS INSTABILITY AND MUCH WEAKER KINEMATIC SUPPORT
   RELATIVE TO AREAS FARTHER SE...WITH UNCERTAINTIES REGARDING EXTENT
   OF RECOVERY ACROSS NEB INTO SD RESULTING FROM OVERNIGHT MCS. 
   STILL...EXPECT SOME SEVERE TSTMS TO DEVELOP IN STRONG DPVA REGION
   IMMEDIATELY AHEAD OF MIDLEVEL CIRCULATION AS IT MOVES ACROSS REGION
   THIS AFTERNOON.  LAPSE RATES SHOULD BECOME VERY STEEP OVER PARTS OF
   NEB...8-9 DEG C/KM...YIELDING MLCAPES 800-1500 J/KG DESPITE COOL
   SURFACE TEMPS.
   
   --- SERN CONUS ---
   SCATTERED TO WIDELY SCATTERED TSTMS SHOULD DEVELOP IN CLUSTERS
   TODAY INVOF NWD-MOVING WARM FRONT OVER LOWER MS/TN VALLEY REGIONS. 
   LARGE HAIL AND WIND DAMAGE EACH SHOULD OCCUR WITH MOST
   PERSISTENT/INTENSE CELLS...AND A FEW TORNADOES ARE ALSO POSSIBLE. 
   VERTICAL SHEAR MAY SUPPORT SUPERCELL STRUCTURES ESPECIALLY WHEN
   COMBINED WITH MESO-BETA TO STORM SCALE BOUNDARY INTERACTIONS.  45-
   60 KT SHEAR IN 0-6 KM AGL LAYER IS POSSIBLE ALONG WITH 150-250 J/KG
   SRH IN 0-3 KM LAYER.  
   
   --- INLAND PACIFIC NW ---
   INSOLATION SHOULD COMBINE WITH STEEPENING MIDLEVEL LAPSE RATES JUST
   AHEAD OF LANDFALLING MID/UPPER LEVEL TROUGH TO PRODUCE 300-500 J/KG
   MLCAPE IN SOME LOCALES THIS AFTERNOON.  THIS WILL SUPPORT SURFACE-
   BASED SHALLOW TSTMS WITH POTENTIAL FOR GUSTS NEAR SEVERE
   LEVELS...BASED ON INCREASING VERTICAL SHEAR THROUGH DEEP LAYER. 
   HOWEVER...ORGANIZED SEVERE POTENTIAL APPEARS TOO LIMITED TO WARRANT
   MORE THAN MARGINAL PROBABILITIES.
   
   ..EDWARDS/NADEN.. 05/04/03
   
   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED FOR 1630Z
        
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