SPC AC 200509
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1209 AM CDT MON JUN 20 2005
   
   VALID 201200Z - 211200Z
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 50 NNW
   MOT MOT 10 NE JMS 35 ESE BRD 45 WNW EAU 25 S RST 30 N FOD 50 SSW PHP
   30 SE BIL 45 NW HVR.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM GPT 40 NE MCB 40 SE
   GLH 30 NNE GLH 15 SSW MEM 45 N MSL 55 SE BNA 40 WSW LOZ 50 N JKL 30
   NE HTS 40 WNW EKN 20 NE EKN 15 ENE ROA 15 SSW DAN FAY 20 ENE ILM.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 80 SSE GBN 40 NNW GBN
   10 ENE IGM 30 NNW SGU 40 ENE MLF CAG 10 S LAR DGW 25 SW GCC COD 30
   WNW JAC 35 ENE SUN 20 N BOI 45 ENE 4LW 15 SSE LMT 35 S MFR 15 NW 4BK
   ...CONT... 55 SE OSC 15 SSE LAN CGX BRL STJ RSL LBL 20 WSW MAF 45 SW
   MRF.
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM CNTRL/SRN MN NWWD INTO ERN
   MT...
   
   ...SYNOPSIS...
   LARGE-SCALE PATTERN THROUGH THE DAY ONE PERIOD CONTINUES TO BE
   CHARACTERIZED BY DOMINANT RIDGE FROM NRN MEXICO/SRN PLAINS INTO THE
   N-CNTRL STATES...WITH MID/UPPER-LEVEL LOWS OVER THE ERN PACIFIC AND
   E COAST. RIDGE AXIS WILL UNDERGO SLIGHT ADJUSTMENT AS AMPLIFYING
   CNTRL CANADIAN SYSTEM CONTRIBUTES TO HEIGHT FALLS OVER THE NRN GREAT
   LAKES...AND HEIGHTS GRADUALLY RISE ACROSS THE NRN ROCKIES INTO SRN
   ALBERTA/SASKATCHEWAN.
   
   IN THE LOW-LEVELS...PRIMARY BAROCLINIC ZONE WILL GRADUALLY SAG SWD
   THROUGH THE UPPER MS VALLEY AND WRN/CNTRL GREAT LAKES WHILE WRN
   EXTENSION RETREATS NWD INTO CNTRL MT IN RESPONSE TO WEAK
   CYCLOGENESIS.
   
   ...CNTRL/SRN MN WWD ACROSS THE DAKOTAS INTO ERN MT...
   LATEST MODEL GUIDANCE SUGGESTS THAT TSTMS WILL LIKELY BE ONGOING AT
   20/12Z ALONG/N FRONTAL SYSTEM OVER PORTIONS OF NRN/CNTRL MN WWD INTO
   THE DAKOTAS WITHIN RATHER WEAK...BUT BROAD LOW-LEVEL WARM ADVECTION
   PATTERN. THOUGH SOME DIURNAL WEAKENING IS EXPECTED TO
   OCCUR...AVAILABILITY OF POTENTIALLY VERY UNSTABLE AIR MASS /I.E.
   MLCAPES OF 3000-4000 J/KG/ S OF FRONTAL ZONE WILL SUPPORT STORM
   INTENSIFICATION/RENEWED DEVELOPMENT BY AFTERNOON FROM PORTIONS OF
   CNTRL/SRN MN WWD INTO SD. STRONGEST BELT OF MID-LEVEL FLOW WILL
   REMAIN TO THE N ALONG INTERNATIONAL BORDER IN ASSOCIATION WITH CNTRL
   CANADIAN SYSTEM. HOWEVER BACKED LOW-LEVEL WINDS INVOF OF FRONT AND
   ANY OUTFLOW BOUNDARIES WILL LIKELY CONTRIBUTE TO SUFFICIENT
   DEEP-LAYER SHEAR FOR ORGANIZED...SEVERE STORMS INCLUDING SUPERCELLS
   WITH POTENTIAL FOR MAINLY LARGE HAIL AND DAMAGING WINDS. AN ISOLATED
   TORNADO OR TWO IS POSSIBLE ALONG THESE BOUNDARIES WHERE LOW-LEVEL
   SHEAR WILL BE LOCALLY ENHANCED.
   
   ADDITIONAL SEVERE STORMS WILL BECOME INCREASINGLY LIKELY LATE THIS
   AFTERNOON INTO EVENING OVER PORTIONS OF CNTRL/ERN MT OWING TO
   INCREASED UPSLOPE FLOW AND SUSTAINED CONVERGENCE NEAR DEVELOPING
   SURFACE LOW AND ATTENDANT FRONTAL ZONE. HERE...COMBINATION OF
   MODERATE INSTABILITY /MLCAPES OF 1500-2500 J/KG/ AND RELATIVELY
   STRONG DEEP-LAYER SHEAR /EFFECTIVE BULK SHEARS OF 45-60 KTS/ WILL
   SUPPORT THE DEVELOPMENT OF SUPERCELLS CAPABLE OF LARGE
   HAIL...DAMAGING WINDS AND AN ISOLATED TORNADO OR TWO. UPSCALE GROWTH
   INTO CLUSTERS OR A MCS WILL LIKELY OCCUR OVERNIGHT WITH ISOLATED
   SEVERE WIND/HAIL THREAT SPREADING EWD INTO WRN/CNTRL ND AND POSSIBLY
   NWRN SD.
   
   ...ERN TN VALLEY/SRN APPALACHIANS INTO FL...
   COMBINATION OF RATHER COOL MID-LEVEL TEMPERATURES ASSOCIATED WITH
   UPPER TROUGH AND A RELATIVELY MOIST BOUNDARY LAYER ARE EXPECTED TO
   CONTRIBUTE TO A WEAKLY CAPPED AND MODERATELY UNSTABLE AIR MASS LATER
   TODAY FROM THE TN VALLEY/SRN APPALACHIANS SWD INTO FL. CURRENT WATER
   VAPOR IMAGERY SHOWS SEVERAL WEAK VORTICITY LOBES ROTATING AROUND
   MAIN CIRCULATION...WHICH WHEN COUPLED WITH THE WEAK CAP WILL AID THE
   DEVELOPMENT OF NUMEROUS TSTM BY AFTERNOON. MID/HIGH-LEVEL WIND
   MAXIMA FROM ERN KY INTO WRN AL AND ACROSS THE NRN AND CNTRL FL
   PENINSULA MAY SUPPORT MORE ORGANIZED STORM DEVELOPMENT WITH THE
   POTENTIAL FOR ISOLATED LARGE HAIL AND DAMAGING WINDS.
   
   ...PACIFIC NW...
   RATHER COLD MID-LEVEL TEMPERATURES E OF ERN PACIFIC UPPER LOW
   COUPLED WITH DAYTIME HEATING ARE ONCE AGAIN EXPECTED TO CONTRIBUTE
   TO POCKETS OF WEAK INSTABILITY LATER TODAY FROM NWRN ORE NWD TO
   PUGET SOUND WITH MLCAPES APPROACHING 500-700 J/KG. APPEARS THE
   DYNAMIC FORCING FOR ASCENT WILL NOT BE QUITE AS STRONG ACROSS AREA
   AS WAS THE CASE SUNDAY OWING TO SLIGHT WWD RETROGRESSION OF UPPER
   LOW. NONETHELESS...DAYTIME HEATING AND OROGRAPHIC ASCENT SHOULD AID
   IN THE DEVELOPMENT OF A FEW STRONG STORMS CAPABLE OF ISOLATED LARGE
   HAIL AND GUSTY WINDS.
   
   ..MEAD/TAYLOR.. 06/20/2005
   
   ...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 1300Z