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    May-19-2004 1630 UTC Day 1 Convective Outlook
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   SPC AC 191637
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1137 AM CDT WED MAY 19 2004
   
   VALID 191630Z - 201200Z
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 25 E
   ECG 35 SE BWG 30 NNW SGF 10 ESE HSI 30 SE SNY 20 WNW AIA 35 N PIR 45
   N MOT ...CONT... 65 WNW ANJ 40 SSE ESC 30 SSW MSN 40 SW RFD 25 SSW
   MMO 10 WNW LAF 25 NNW DAY 30 SSE HLG 20 SE ACY.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 25 NNW MLB 20 NW FMY.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 15 SE BPT 15 NNE ESF
   35 SW GWO 15 E MEM 35 ESE JBR ARG 15 W UMN 40 SSW EMP 15 W HUT 35
   WNW GAG 50 SE LBB 30 SSE P07.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 10 NNE ERI 10 SSE ELM
   10 W MSV 25 SSW GON.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 40 S DMN 45 SE GNT 20
   E RTN 35 SSE LIC 35 WSW AKO 10 WNW FCL 15 NNE SLC 60 NW ELY 45 SSE
   NFL 30 WSW TVL 35 ESE UKI 35 ENE ACV 35 N MFR 35 N SEA 20 NE BLI.
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE NRN PLAINS INTO THE OH
   RIVER VALLEY TO VA...
   
   ...CENTRAL/NRN PLAINS INTO THE NRN MS RIVER VALLEY...
   STRONG IMPULSE NOW EJECTING INTO THE NRN PLAINS WILL CONTINUE ENEWD
   AS A POSITIVELY TILTED TROUGH THROUGH THE EVENING.  ASSOCIATED MID
   LEVEL JET WILL OVERSPREAD THE NRN PLAINS AND SUPPORT STRONG DEEP
   LAYER SHEAR FROM THE MID MO RIVER VALLEY NWD.  IN RESPONSE TO THIS
   SYSTEM...A SURFACE LOW WILL TRACK EWD ACROSS NRN ND TODAY WITH
   TRAILING COLD FRONT PUSHING SWD ACROSS THE NRN HIGH PLAINS.  LARGE
   AREA OF DENSE OVERCAST/FOG WILL HINDER DESTABILIZATION INTO THE ERN
   NEB/ERN DAKOTAS.  HOWEVER AS HEATING CONTINUES THROUGH THE EARLY
   AFTERNOON...MUCH OF THIS LOW CLOUD DECK MAY BREAK UP AND SUPPORT
   AXIS OF MODERATE TO STRONG INSTABILITY WITHIN THE WARM SECTOR BY THE
   LATE AFTERNOON.  UNCERTAINTIES REMAIN TOO GREAT THIS LATE IN THE
   FORECAST PROCESS TO JUSTIFY A MODERATE RISK /ESPECIALLY WITH THE
   EXTENSIVE LOW CLOUD DECK/.  HOWEVER...CONDITIONAL SIGNIFICANT SEVERE
   FORECASTS WILL BE CONTINUED IN THE PROBABILITIES.
   
   THE CENTRAL PLAINS WILL BE PLACED UNDER RISING HEIGHTS/ TEMPERATURES
   ALOFT. THEREFORE IT APPEARS HIGHER POTENTIAL FOR SEVERE
   THUNDERSTORM DEVELOPMENT WILL OCCUR AHEAD OF SURFACE TROUGH/COLD
   FRONT INTO ERN ND AND ERN SD/NERN NEB AROUND 21Z...PENDING ON
   DESTABILIZATION AS EXPECTED.  THIS REGION WILL REMAIN UNDER
   FAVORABLE LARGE SCALE ASCENT AND PARAMETERS WILL SUPPORT SUPERCELLS
   AND POSSIBLE TORNADOES FROM AROUND 20Z-02Z.  AFTER WHICH...ACTIVITY
   WILL RIDE EAST OF SURFACE-BASED INSTABILITY AND BECOME INCREASINGLY
   ELEVATED ALONG LLJ AXIS INTO THE NRN MS RIVER VALLEY AND WRN GREAT
   LAKES. LARGE HAIL WILL BECOME MAIN THREAT WITH THESE STORMS
   OVERNIGHT.  TAIL END OF THIS ACTIVITY MAY EVOLVE INTO A BOW ECHO
   SYSTEM AND TRACK ESEWD ALONG INSTABILITY/CAP GRADIENT ACROSS IA
   THROUGH THE EVENING.
   
   OTHER ISOLATED SEVERE THUNDERSTORMS MAY DEVELOP VERY RAPIDLY WITHIN
   EXTREME INSTABILITY SHOULD CAP BREAK ALONG OUTFLOW BOUNDARY INTO
   NERN KS/NWRN MO/SERN NEB/SWRN IA.  LOW AND DEEP LAYER SHEAR WILL
   ALSO BE FAVORABLE FOR TORNADIC SUPERCELLS.  HOWEVER...EXTENT OF LOW
   CLOUDS AND STRENGTH OF CAP SUGGEST THIS SCENARIO IS HIGHLY
   CONDITIONAL.
   
   ...HIGH PLAINS...
   DEEP MIXING WITHIN HOT BOUNDARY LAYER MAY ALLOW CAP TO ERODE AND
   SUPPORT A FEW AREAS OF THUNDERSTORMS FROM WRN NEB INTO WRN TX. 
   SEVERE THREAT WOULD BE HIGHER INTO THE CENTRAL PLAINS...SHOULD THIS
   OCCUR...DUE TO THE STRONGER SHEAR.
   
   ...VA INTO THE OH RIVER VALLEY...
   SURFACE FRONT EXTENDING FROM THE VA COAST WWD INTO THE OH RIVER
   VALLEY WILL REMAIN IN PLACE THIS AFTERNOON.  THIS BOUNDARY WILL THEN
   LIFT NWD TOWARDS THE SRN GREAT LAKES LATER IN THE PERIOD AHEAD OF
   STRONG SYSTEM LIFTING OUT OF THE NRN PLAINS.  WEAK IMPULSE EVIDENT
   ON WV IMAGERY IS FORECAST BY THE RUC/ETA TO SHIFT ACROSS VA THIS
   AFTERNOON...AND SHOULD ENHANCE THUNDERSTORM COVERAGE/INTENSITY AS
   AIR MASS BECOMES MODERATELY UNSTABLE EAST OF THE MOUNTAINS.  FARTHER
   WEST ALONG THE FRONT...A BROAD RESERVOIR OF MODERATE TO STRONG
   INSTABILITY WILL DEVELOP ACROSS THE WARM SECTOR.  GIVEN THE WEAK CAP
   AND CONVERGENCE NEAR THE FRONT...NUMEROUS THUNDERSTORMS WITH
   ATTENDANT LARGE HAIL/DAMAGING WINDS ARE EXPECTED TO DEVELOP.  DEEP
   LAYER SHEAR IS MARGINAL /20-30 KT FROM 0-6 KM/...YET WILL STILL BE
   SUPPORTIVE OF MULTICELL LINES/CLUSTERS.
   
   ..EVANS/CROSBIE.. 05/19/2004
   
   ...NOTICE...
   FOR USERS DECODING THE POINTS PARAGRAPH HEREIN...LATITUDE AND
   LONGITUDE POINTS FOR THE CATEGORICAL AND PROBABILISTIC OUTLOOK
   GRAPHICS ALSO ARE LOCATED IN A SEPARATE PRODUCT UNDER THE WMO
   HEADINGS WUUS01 PTSDY1...WUUS02 PTSDY2...AND WUUS03 PTSDY3.  THE
   INCLUSION OF POINTS IN THIS PRODUCT WILL EVENTUALLY BE DISCONTINUED.
   
   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED FOR 2000Z