SPC AC 040116
STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK
DAY 1 CONVECTIVE OUTLOOK...REF AWIPS GRAPHIC PGWE46 KWNS.
VALID 040100Z - 041200Z

THERE IS A MDT RISK OF SVR TSTMS TONIGHT ACROSS CNTRL AND ERN NEB.
THE MDT RISK AREA IS TO THE RIGHT OF A LINE FROM 25 ESE IML 40 WNW
MHN VTN 15 NW OFK 40 NW OMA 25 NW FNB 35 WNW CNK 25 ESE IML.

THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM
30 SE BVE 20 NE LCH 25 SSW LFK 25 S BWD 20 NNE BGS PVW 10 SW EHA
AKO 40 NE 81V 60 SE GDV 55 WNW DVL 50 N GFK 25 WNW AXN 40 NE LWD
15 NE COU 45 WNW POF 25 SE JBR UOX 25 SSW CBM 45 SW SEM 20 W CEW
30 ESE PNS.

THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM SSI
50 WSW AGS 15 NNW AND AVL 35 W HKY 40 ENE HKY 15 NE FAY 20 SSE ILM.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 15 SSE P07
10 WNW MAF 45 SE CVS 15 SW CAO 20 S ALS CEZ GCN EED DAG 15 NW PMD
SMX SJC MHS RDM PDT PUW 90 WNW FCA ...CONT... 10 S INL STC
35 SE MKT 20 NW ALO 20 NNW BRL ALN 45 NE MKL 40 SSW BNA 35 NNW CSV
40 NNW JKL CMH CAK 20 SSW FKL 15 NW AOO HGR 20 W DCA 15 S NHK
10 ESE SBY ...CONT... 15 SW GLS SAT 70 W COT.

...SYNOPSIS...
ACTIVE WEATHER PATTERN WILL CONTINUE ACROSS THE CONUS TONIGHT AS
SHORTWAVE TROUGH AND ASSOCIATED MID AND UPPER-LEVEL JET TRANSLATE
FROM THE DESERT SW INTO THE CNTRL HIGH PLAINS BY 12Z SUNDAY.
DOWNSTREAM SHORTWAVE TROUGH OVER THE OH VALLEY WILL PROGRESS EWD
INTO THE DELMARVA REGION IN RESPONSE TO HEIGHT RISES OVER THE MS
VALLEY.
AT THE SURFACE...BAROCLINIC ZONE STRETCHING FROM SWRN KS ACROSS THE
RED RIVER VALLEY AND THEN EWD TO AN AREA OF LOW PRESSURE OVER THE
WRN CAROLINAS WILL CONTINUE TO SERVE AS A FOCUS FOR SEVERE WEATHER
THROUGH THE PERIOD. THE WRN END OF THIS FRONT WILL CONTINUE TO LIFT
NWD THROUGH THE PLAINS OVERNIGHT IN RESPONSE TO CYCLOGENESIS OVER
SWRN NEB WHILE DRYLINE REMAINS QUASI-STATIONARY ACROSS THE HIGH
PLAINS THROUGH A GOOD PART OF THE NIGHT. THE ERN END OF THE FRONT
WILL SLOWLY SAG SWD THROUGH THE CAROLINAS AS SECONDARY LOW MOVES
EWD OFF THE COAST.


...SOUTHERN PLAINS EWD INTO THE CNTRL GULF COAST...
LARGE SUPERCELL CONTINUES TO MOVE ESEWD THIS EVENING OVER HASKELL
COUNTY TX TO THE S OF WARM FRONT THAT CURRENTLY EXTENDS FROM SWRN
KS SEWD ACROSS SWRN OK AND THEN EWD ACROSS NRN LA INTO CNTRL MS.
ADDITIONAL TSTMS...INCLUDING LEFT-MOVING SUPERCELLS...ARE IN
PROGRESS OVER SWRN OK W OF HOBART. STEEP-MID LEVEL LAPSE RATES AND
DEWPOINTS IN THE MID 60S TO LOWER 70S ACROSS THE WARM SECTOR OVER
TX INTO FAR SRN OK IS CONTRIBUTING TO A MODERATELY TO VERY UNSTABLE
AIRMASS WITH MLCAPES OF 2000-3000 J/KG. MOREOVER...DEEP-LAYER /0-
6KM/ SHEAR ON THE ORDER OF 50-60KTS WILL CONTINUE TO SUPPORT A
SUPERCELL THREAT THROUGH THE EVENING AND OVERNIGHT HOURS.
LATEST WATER VAPOR IMAGERY SUGGESTS THAT MID-LEVEL RIDGING
CONTINUES TO SHIFT EWD FROM THE SRN PLAINS INTO THE LOWER MS VALLEY
WITH BACKING 500MB WINDS NOTED IN THE NM PROFILER DATA. PRIMARY
QUESTION IS WHETHER LARGE-SCALE FORCING FOR ASCENT WILL BE
SUFFICIENT TO INITIATE ADDITIONAL TSTMS INVOF DRYLINE/WARM FRONT.
LATEST MESOANALYSIS INDICATES THAT THE BEST LOW-LEVEL CONVERGENCE
IS OCCURRING OVER THE ERN TX PNHDL ATTM WHERE INCREASING SELY WINDS
ACROSS WRN OK ARE IMPINGING ON DRYLINE WHICH EXTENDS FROM E OF AMA
SWD INTO THE LOW ROLLING PLAINS. IF STORMS CAN INITIATE IN THIS
AREA OVER THE NEXT FEW HOURS...SUPERCELLS ARE LIKELY. LARGE HAIL
AND ISOLATED TORNADOES WILL BE THE PRIMARY THREATS.
ONGOING TSTMS OVER SRN MS/SWRN AL SHOULD CONTINUE TO PROGRESS SEWD
OFF THE COAST WITHIN THE NEXT COUPLE OF HOURS. ADDITIONAL
DEVELOPMENT IS POSSIBLE OVERNIGHT AS INCREASING LLJ ENHANCES
LIFT/CONVERGENCE ALONG WARM FRONT/STATIONARY BOUNDARY FROM NRN LA
EWD ACROSS CNTRL MS. LARGE HAIL WOULD BE THE PRIMARY SEVERE WEATHER
THREAT WITH ANY SUBSEQUENT STORM DEVELOPMENT.

...NRN/CNTRL PLAINS...
CLUSTERS OF STRONG TO SEVERE TSTMS ARE ONGOING THIS EVENING ACROSS
THE DAKOTAS SWD INTO WRN NEB WHERE SUPERCELLS ARE IN PROGRESS OVER
GARDEN/MORRILL COUNTIES. ALTHOUGH SURFACE DEWPOINTS ARE ONLY IN THE
LOWER TO MID 50S...COOL MID-LEVEL TEMPERATURES /-16 TO -18C/ ARE
HELPING CONTRIBUTE TO A MODERATELY UNSTABLE AIRMASS E OF
DRYLINE/LEE TROUGH WITH MLCAPES OF 500-1500 J/KG. WHILE THE THREAT
OF AN ISOLATED TORNADO WILL CONTINUE FOR THE NEXT COUPLE OF HOURS
WITH SUPERCELLS OVER WRN NEB...IT APPEARS THAT THE PRIMARY SEVERE
WEATHER THREAT OVERNIGHT WILL BE LARGE HAIL. CURRENT PROFILER/VWP
PLAN VIEW DATA INDICATE LLJ STRENGTHENING FROM WRN/CNTRL KS NWD
INTO THE DAKOTAS. LATEST MODEL GUIDANCE SUGGESTS THIS TREND WILL
CONTINUE OVERNIGHT WITH 50-60KT LLJ AXIS SLOWLY SHIFTING EWD ACROSS
THE NRN/CNTRL PLAINS IN RESPONSE TO STRONG HEIGHT FALLS THAT WILL
BE OCCURRING OVER THE HIGH PLAINS.
ONGOING TSTMS WILL LIKELY CONGEAL INTO ONE OR TWO MCS/S OVERNIGHT
WHICH WILL PROPAGATE EWD INTO MN/IA AND POSSIBLY WRN MO. CURRENT
INDICATIONS ARE THAT THE MOST WIDESPREAD AND SIGNIFICANT SEVERE
WEATHER POTENTIAL WILL EXIST AFTER 03-05Z ACROSS CNTRL/ERN NEB
WHERE THE STRONGEST FORCING FOR LARGE-SCALE ASCENT WILL CO-EXIST
WITH MODERATE AMOUNTS OF ELEVATED INSTABILITY /1500-2500 J/KG OF
MUCAPE/ AND 40-50KTS OF SHEAR THROUGH THE CLOUD-BEARING LAYER. HERE
SUPERCELLS WILL LIKELY DEVELOP AMONG A BROADER AREA OF TSTMS WITH
THE POTENTIAL FOR LARGE HAIL AND SOME DAMAGING WINDS.

...CAROLINAS...
AIRMASS ACROSS MUCH OF SC AND SERN NC REMAINS MODERATELY UNSTABLE
THIS EVENING WITH MLCAPES OF 1000-1500 J/KG. COMBINATION OF FORCING
FOR ASCENT WITH SHORTWAVE TROUGH MOVING THROUGH THE AREA AND LOW-
LEVEL CONVERGENCE INVOF SURFACE LOW AND ATTENDANT FRONTAL
BOUNDARIES WILL SUSTAIN STRONG/SEVERE TSTMS THROUGH THE EVENING
HOURS. DEEP-LAYER SHEAR OF 30-40KTS WILL SUPPORT ORGANIZED
TSTMS...INCLUDING A FEW SUPERCELLS EMBEDDED IN ONGOING CONVECTIVE
CLUSTERS. LARGE HAIL AND DAMAGING WINDS WILL BE THE PRIMARY SEVERE
WEATHER THREATS. HOWEVER...AN ISOLATED TORNADO REMAINS POSSIBLE
INVOF BACKDOOR FRONTAL BOUNDARY CURRENTLY EXTENDING FROM SERN NC WW
TO SURFACE LOW WHERE BACKED LOW-LEVEL WINDS WILL ENHANCE SHEAR
PROFILES.

..MEAD.. 05/03/03