Apr-11-2005 1630 UTC Day 1 Convective Outlook
Updated: Mon Apr 11 17:32:12 UTC 2005
Public Severe Weather Outlook

The SPC is forecasting an outbreak of severe thunderstorms today and tonight across portions of the United States. This is an extremely dangerous situation. Please read the latest public statement about this event.

Categorical Graphic
20050411 1630 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20050411 1630 UTC Day 1 Tornado Probabilities Graphic
Probabilistic Damaging Wind Graphic
20050411 1630 UTC Day 1 Damaging Wind Probabilities Graphic
Probabilistic Large Hail Graphic
20050411 1630 UTC Day 1 Large Hail Probabilities Graphic
   SPC AC 111627
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1127 AM CDT MON APR 11 2005
   
   VALID 111630Z - 121200Z
   
   THERE IS A HIGH RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 15 ESE
   POE 25 W ESF 35 N ESF 25 ESE MLU 30 S GLH 40 NNW JAN JAN 45 NW BTR
   40 NW LFT 35 SE POE 15 ESE POE.
   
   THERE IS A MDT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 30 NE
   UOX 20 ESE TUP 15 SSE CBM 10 NE LUL 20 SE MCB LFT 15 SSE LCH BPT 35
   N BPT 40 W POE 55 SE SHV 30 NW MLU 35 N GLH 45 SSW MEM 25 NNW UOX 30
   NE UOX.
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 10 SE
   PSX 20 W HOU 20 ENE GGG 15 N PGO BVO 20 E HUT 60 SSW HSI 20 NNW EAR
   45 WNW OFK 30 SE FSD FRM 35 S RST SPI 40 SE MVN 20 WNW BNA 45 WSW
   CHA AUO 30 WNW PFN.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 80 NW FCA 45 SW MSO
   20 SW S80 40 S PDT 70 SW PDT 40 SSW DLS ONP.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 40 NE CRP 50 SSE AUS
   60 E ACT 20 NNW PRX 15 NNW TUL 20 SW ICT 45 WSW RSL 20 S MCK 30 SE
   ANW 20 NNE 9V9 20 W ABR 25 SE DVL 35 N TVF 45 SE RRT 25 W DLH 15 S
   MKE 25 ESE DAY 30 SW EKN 55 E DAN GSB 20 ESE FAY 45 WNW FLO 20 ENE
   AVL 30 S TYS 50 WNW AHN 40 SE ATL 10 ESE AQQ.
   
   ...THERE IS A HIGH RISK OF SVR TSTMS ACROSS A SMALL PART OF ERN LA
   AND WEST CENTRAL MS...
   
   ...THERE IS A MDT RISK OF SVR TSTMS EXTREME SERN TX...LA AND MS...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS MID AND LOWER MS VALLEY
   REGION...
   
   ...SIGNFICANT SEVERE WEATHER EVENT...INCLUDING STRONG TORNADOES...
   ARE POSSIBLE THIS AFTERNOON AND EVENING FROM EXTREME SERN TX EWD
   ACROSS SRN/ERN LA...EXTREME SERN AR AND MOST OF MS.
   
   ...SERN TWX EWD ACROSS THE LOWER MS VALLEY...
   BAND OF STRONG/SEVERE THUNDERSTORMS EXTENDS FROM SERN AR SWWD INTO
   SERN TX AND IS ONLY MOVING EWD AT 15 KT DUE TO STRONG MERIDIONAL LOW
   ALOFT. DEEPER TROPICAL AIR MASS HAS LIFTED NWD ACROSS SRN LA WITH
   MID/UPPER 60 DEWPOINTS RESULTING IN MUCAPES UP TO 1500 J/KG. THIS
   DEEPER BOUNDARY LAYER MOISTURE WILL SPREAD NWD ACROSS THE SRN HALF
   OF MS THIS AFTERNOON AND WITH HEATING...MODERATE INSTABILITY WILL BE
   PREVALENT ACROSS THE REGION. AHEAD OF THE THUNDERSTORM LINE...LIFT
   WILL BE ACCENTUATED BY VERY STRONG DIFFLUENT FLOW ALOFT AND LOW
   LEVEL WARM ADVECTION...WHICH SHOULD AID IN THUNDERSTORM INITIATION
   AHEAD OF THE LINE. DEEP LAYER SHEAR WILL STRENGTHEN TO NEAR 60 KT
   LATER TODAY AS A 75 KT SPEED MAX IN SWRN TX MOVES INTO THE AREA. THE
   STRENGTH OF THE DEEP LAYER SHEAR AND INSTABILITY WILL BE FAVORABLE
   FOR SUPERCELLS.  ALSO...SELY LOW LEVEL WINDS VEERING TO SWLY IN THE
   MID LEVELS ARE RESULTING IN STRONGLY CURVED HODOGRAPHS...WITH 1KM
   SRH BETWEEN 200-250 M2/S2. THE LOW/DEEP LAYER SHEAR AND INSTABILITY
   WOULD SUPPORT TORNADOES ...SOME WHICH MAY BE STRONG AND LONG LIVED.
   THE TORNADO THREAT WILL BE THE GREATEST WHERE STRONGER INSOLATION
   OCCUR THIS AFTERNOON. AT THIS TIME...THE HIGHEST TORNADO THREAT
   APPEARS TO EXTEND FROM CENTRAL LA NEWD INTO WEST CENTRAL MS DURING
   THE MID/LATE AFTERNOON HOURS.
   
   AS A SPEED MAX IN SWRN TX LIFTS NEWD INTO THE LOWER MS VALLEY
   TONIGHT...THE CONVECTIVE LINE...CURRENTLY ACROSS LA/SERN TX...IS
   EXPECTED TO ACCELERATE EWD AS THE TROUGH ALOFT BECOMES NEGATIVELY
   TILTED. THE MAIN SEVERE WEATHER THREAT SHOULD TRANSITION TO A 
   DAMAGING WIND THREAT ACROSS THE MS AND AL OVERNIGHT.
   
   ...ERN KS/WRN MO NWD TO SE NEB/SW IA...
   LOW/MID LEVEL LOW OVER CENTRAL KS WILL SHIFT EWD INTO MO TONIGHT.
   THE COMBINATION OF COLD MID LEVEL TEMPERATURES/500 MB TEMPERATURES
   FROM -20 TO -22C/ AND SURFACE DEWPOINTS IN THE MID 50S WILL BE
   SUPPORTIVE OF MODERATE INSTABILITY THIS AFTERNOON. STEEP LAPSE RATES
   AND COLD MID LEVEL TEMPERATURES SUGGEST THAT LARGE HAIL WILL BE
   POSSIBLE EAST OF THE LOW THIS AFTERNOON...WHERE THE LARGE SCALE LIFT
   WILL BE THE STRONGEST. THE PRESENCE OF STRONG VORTICITY NEAR THE
   UPPER LOW COMBINED WITH LOW LEVEL ELY/SELY WINDS EAST OF THE SURFACE
   LOW MAY BE SUPPORT A FEW TORNADOES.
   
   ...EXTREME ERN OK/WRN AR/SW MO AREA THIS AFTERNOON/EVENING...
   DRYLINE/COLD FRONT WILL MOVE SLOWLY EWD THIS AFTERNOON. DEWPOINTS IN
   THE MID/UPPER 50S AND A FEW BREAKS IN THE CLOUDS MAY ALLOW
   SUFFICIENT DESTABILIZATION FOR THUNDERSTORM DEVELOPMENT. THE DEEP
   LAYER SHEAR REMAINS STRONG AND GIVEN WEAK INSTABILITY...ANY
   STORMS THAT FORM COULD PRODUCE MARGINALLY SEVERE HAIL AND DAMAGING
   WIND GUSTS.
   
   ..IMY.. 04/11/2005
   
   ...NOTICE...
   THE STATION RELATIVE POINTS IN THIS PRODUCT ARE NOW AVAILABLE
   SEPARATELY UNDER THE WMO HEADINGS WUUS01 PTSDY1...
   WUUS02 PTSDY2...WUUS03 PTSDY3.  THE INCLUSION OF POINTS
   IN THIS DISCUSSION WILL BE DISCONTINUED AFTER THE 2005
   CONVECTIVE SEASON.  A PUBLIC NOTIFICATION STATEMENT (PNS)
   WILL PROVIDE DETAILS ON THE TRANSITION.
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z