Jun 4, 2005 1300 UTC Day 1 Convective Outlook
Updated: Sat Jun 4 11:16:08 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
20050604 1300 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20050604 1300 UTC Day 1 Tornado Probabilities Graphic
Probabilistic Damaging Wind Graphic
20050604 1300 UTC Day 1 Damaging Wind Probabilities Graphic
Probabilistic Large Hail Graphic
20050604 1300 UTC Day 1 Large Hail Probabilities Graphic
   SPC AC 041108
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0608 AM CDT SAT JUN 04 2005
   
   VALID 041300Z - 051200Z
   
   THERE IS A HIGH RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM BIE 30
   SSE SUX 25 S FOD P35 20 WNW SZL 60 SSE OJC CNU 40 SW EMP BIE.
   
   THERE IS A MDT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM MKT 25
   WSW RST ALO IRK 25 W COU UMN MKO ADM FSI SLN OFK 25 WSW OTG MKT.
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 35 ESE
   P07 45 N SJT LTS P28 RSL MCK LBF ANW 35 SSE FAR 50 N BRD 40 E DLH 40
   NE RHI 35 ENE GRB CGX DEC HRO PRX TPL 50 SSE DRT.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 25 SE P07 20 SSW CDS
   15 SW GAG 30 SSW DDC 35 SW GCK 40 NNW EHA 35 NE CAO 35 WSW DHT 45 NW
   TCC 20 NE SAF 35 SSW FMN 35 S U17 35 N BCE 15 S DPG 50 ENE SUN 45 W
   BTM 30 NW CTB ...CONT... 60 NNE GGW 15 W MLS 10 E SHR 45 SE WRL 45 N
   RWL 25 ESE FCL 20 WSW AKO 40 SE SNY 15 NNW MHN 15 NE MBG 60 NE MOT
   ...CONT... 35 ENE CLE 25 SW PKB 20 ESE PSK 25 E DAN 20 ENE ECG
   ...CONT... 40 SSW HUM 45 N LFT 35 WSW MLU 20 ENE SHV 35 SSW GGG 20
   SSE SAT 30 NW LRD.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 35 SW BHB 20 SSE BTV
   15 W MSS.
   
   ...THERE IS A HIGH RISK OF SVR TSTMS THIS AFTERNOON AND TONIGHT OVER
   PARTS OF SOUTHEAST NEB...SOUTHWEST IA...EASTERN KS...AND WESTERN
   MO...
   
   ...THERE IS A MDT RISK OF SVR TSTMS FROM SOUTHERN OK NORTHWARD INTO
   FAR SOUTHERN MN...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF TX INTO MN/WI...
   
   ...OUTBREAK OF SEVERE THUNDERSTORMS AND TORNADOES IS FORECAST TODAY
   OVER PARTS OF THE CENTRAL PLAINS...
   
   MORNING WATER VAPOR IMAGERY SHOWS LARGE UPPER TROUGH AXIS OVER THE
   NORTHERN/CENTRAL HIGH PLAINS.  TWO WELL-DEFINED SHORTWAVE TROUGHS
   ARE ROTATING THROUGH THIS REGION.  THE FIRST TROUGH IS NOW OVER
   NORTHWEST MO AND WILL LIFT INTO THE UPPER MS VALLEY TODAY.  THE
   SECOND TROUGH WILL ROTATE INTO THE CENTRAL PLAINS BY LATE
   AFTERNOON...SETTING THE STAGE FOR A SIGNIFICANT SEVERE WEATHER
   EPISODE THIS EVENING.
   
   ...ERN NEB/IA/ERN KS/MO...
   LATEST SURFACE ANALYSIS SHOWS A VERY MOIST LOW LEVEL AIRMASS IN
   PLACE THIS MORNING ACROSS MUCH OF OK/TX AND WESTERN AR...WITH
   DEWPOINTS IN THE UPPER 60S TO LOWER 70S.  SCATTERED THUNDERSTORMS
   ARE ONGOING OVER PARTS OF KS/MO...BUT THIS ACTIVITY SHOULD LIFT
   STEADILY NORTHWARD THROUGH THE DAY AS LEAD SHORTWAVE TROUGH DEPARTS
   REGION.  STRONG SOUTHERLY LOW LEVEL WINDS AT AND ABOVE THE SURFACE
   WILL HELP TRANSPORT MARITIME AIR MASS NORTHWARD TODAY...WITH HIGH
   THETA-E AIR EXPECTED INTO MUCH OF EASTERN NEB AND IA BY MID
   AFTERNOON.  VERY STRONG DIURNAL HEATING IS ALSO EXPECTED THROUGHOUT
   THIS REGION AFTER MORNING CLOUDS ERODE...RESULTING IN AN EXTREMELY
   UNSTABLE AIRMASS /MLCAPE VALUES OF 3000-4000 J/KG POSSIBLE/. 
   SHORTWAVE RIDGING IN WAKE OF LEAD SHORTWAVE TROUGH WILL PROVIDE A
   RATHER STRONG CAPPING INVERSION ACROSS THE WARM SECTOR THROUGH MID
   AFTERNOON...SUPPRESSING DEEP CONVECTION.
   
   AS PRIMARY SHORTWAVE TROUGH APPROACHES THE WARM SECTOR BY LATE
   AFTERNOON...CAP IS EXPECTED TO ERODE ALONG SURFACE DRYLINE EXTENDING
   FROM SOUTHERN NEB INTO EAST-CENTRAL KS.  EXPLOSIVE THUNDERSTORM
   DEVELOPMENT IS FORECAST IN THIS AREA.  STRENGTHENING WIND FIELDS AT
   ALL LEVELS DURING THE LATE AFTERNOON...COUPLED WITH EXTREME
   INSTABILITY...WILL PROMOTE THE HIGH PROBABILITY OF SUPERCELL
   THUNDERSTORMS CAPABLE OF VERY LARGE HAIL AND TORNADOES.  STORMS ARE
   EXPECTED TO TRACK EAST-NORTHEASTWARD INTO PARTS OF WESTERN IA AND
   WESTERN MO DURING THE EVENING WITH A CONTINUED THREAT OF SIGNIFICANT
   SEVERE.  FORECAST SOUNDINGS ACROSS THE HIGH RISK AREA SHOW EFFECTIVE
   DEEP LAYER SHEAR VALUES OF 40-50 KNOTS...AND EFFECTIVE HELICITY
   VALUES OF 200-300 M2/S2 DURING THE EVENING AS LOW LEVEL WINDS BACK
   AND STRENGTHEN IN RESPONSE TO APPROACHING UPPER TROUGH.  COMBINATION
   OF VERY FAVORABLE VERTICAL SHEAR PARAMETERS...LOW LCL HEIGHTS...RICH
   LOW LEVEL MOISTURE...AND EXTREME INSTABILITY INDICATE THE THREAT OF
   STRONG TORNADOES THIS EVENING.
   
   ...OK/TX...
   SURFACE DRYLINE IS FORECAST TO EXTEND FROM NORTH CENTRAL OK INTO
   CENTRAL TX BY LATE AFTERNOON.  FULL SUNSHINE...AMPLE MOISTURE...AND
   STEEP MID LEVEL LAPSE RATES WILL YIELD A VERY UNSTABLE AIRMASS ALONG
   AND EAST OF DRYLINE THIS AFTERNOON WITH MLCAPE VALUES OVER 3000
   J/KG.  PRIMARY DYNAMIC FORCING ASSOCIATED WITH CENTRAL PLAINS TROUGH
   WILL BE FROM SOUTHERN KS NORTHWARD.  HOWEVER...MODEL FORECAST
   SOUNDINGS SUGGEST THAT CONVECTIVE TEMPERATURES WILL LIKELY BE
   REACHED ALONG THE DRYLINE ACROSS PARTS OF TX/OK...WITH THE
   DEVELOPMENT OF WIDELY SCATTERED THUNDERSTORMS. VERTICAL SHEAR
   PROFILES IN THIS REGION WILL SUPPORT SUPERCELLS CAPABLE OF VERY
   LARGE HAIL AND DAMAGING WINDS. TORNADOES ALSO APPEAR
   POSSIBLE...MAINLY ALONG OK PORTION OF DRYLINE...WHERE STRONG WIND
   FIELDS WILL BE PRESENT.  STORMS IN THIS REGION MAY DIMINISH BY LATE
   EVENING DUE TO LACK OF DYNAMIC FORCING FOR ASCENT.
   
   ...CENTRAL NEB/EASTERN SD/MN...
   MAIN SURFACE LOW WILL LIKELY BE OVER WESTERN NEB THROUGH LATE
   AFTERNOON...WITH BACKED LOW LEVEL WINDS PROGD ACROSS MUCH OF CENTRAL
   NEB INTO SOUTHEAST SD. PRESENT INDICATIONS ARE THAT SCATTERED
   THUNDERSTORMS WILL FORM THIS AFTERNOON IN THIS REGION. SUFFICIENT
   INSTABILITY AND ENHANCED DEEP LAYER VERTICAL SHEAR WILL PROMOTE A
   RISK OF LARGE HAIL AND DAMAGING WINDS IN STRONGER CELLS.  ACTIVITY
   MAY ALSO SPREAD INTO PARTS OF MN THIS EVENING.
   
   ..HART/BANACOS.. 06/04/2005
   
   ...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 1630Z