SPC AC 110557
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1257 AM CDT SUN SEP 11 2005
   
   VALID 111200Z - 121200Z
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 30 E
   INL 25 SE AXN 30 SW BKX 40 NNE VTN 25 SE PHP 40 WSW MBG 25 S BIS 60
   N DVL.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 20 SW FHU 20 SW SOW
   25 NW CEZ 25 E GUC 25 SSW SNY 40 SE AIA 40 SE RAP 50 ESE REJ 10 WSW
   Y22 45 S P24 50 NNE MOT ...CONT... 145 NNW BUF 20 S APN 50 SSW IMT
   15 W LSE 20 SSW MCW 15 WNW LNK 30 ESE RSL 10 WSW P28 50 NNE CSM FSI
   35 SE SPS 25 SSW FTW 20 E CLL GLS.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 10 SW HQM 30 SSW GEG
   25 NNE HLN 15 SSW SHR 35 NNE RKS 50 S SLC 30 SW P38 60 N NID 30 NNE
   FAT 45 NE SCK 45 NNW SAC 60 NW UKI.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 15 SW BHB 55 W 3B1.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 60 SSW GNV 30 NW SSI
   40 NNE SAV 35 WNW ILM HSE.
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE NRN
   PLAINS...
   
   ...NRN PLAINS...
   A LARGE UPPER-TROUGH OVER THE WRN US WILL BEGIN TO MOVE EWD TODAY
   WITH A LEAD SHORTWAVE TROUGH EJECTING NEWD ACROSS THE REGION.
   ALTHOUGH THE STRONGEST LARGE-SCALE ASCENT ASSOCIATED WITH THE
   SHORTWAVE TROUGH IS FORECAST TO REMAIN ACROSS ERN MT AND WRN
   ND...ENOUGH ASCENT SHOULD SPREAD EWD ACROSS THE ERN DAKOTAS AND WRN
   MN TO SUPPORT THE INITIATION OF SCATTERED STORMS BY THIS EVENING.
   
   AT THE SFC...A COLD FRONT WILL ORGANIZE AND MOVE SEWD REACHING ERN
   ND AND CNTRL SD BY LATE AFTERNOON. SFC DEWPOINTS AHEAD OF THE FRONT
   IN THE 60S F SHOULD RESULT IN MODERATE INSTABILITY. HOWEVER...THE
   AIRMASS SHOULD REMAIN CAPPED DUE TO WARM TEMPS ALOFT ASSOCIATED WITH
   AN ELEVATED MIXED LAYER EVIDENT ON WATER VAPOR SPREADING NEWD ACROSS
   THE REGION. AS ASCENT INCREASES FROM WEST TO EAST ACROSS THE REGION
   DURING THE LATE AFTERNOON AND EARLY EVENING HOURS...THE CAPPING
   INVERSION MAY WEAKEN ENOUGH FOR STORM INITIATION ALONG THE COLD
   FRONT. A STRONG LOW-LEVEL JET NOSING INTO THE REGION FROM THE SOUTH
   SOUTHWEST SHOULD RESULT IN EXPANDING STORM COVERAGE OVERNIGHT.
   NAM/NAMKF AND GFS MODEL FORECASTS ARE CONSISTENT IN DEVELOPING A
   CLUSTER OF STORMS ACROSS THE ERN DAKOTAS IN THE EVENING WITH A STORM
   COMPLEX SPREADING NEWD INTO CNTRL AND NRN MN OVERNIGHT.
   
   THE SHEAR ENVIRONMENT WILL LIKELY BE ENHANCED BY A MID-LEVEL JET
   ASSOCIATED WITH THE LEAD SHORTWAVE TROUGH. FORECAST SOUNDINGS ACROSS
   THE REGION EARLY SUNDAY EVENING SHOW 0-6 KM SHEAR VALUES AROUND 40
   KT WITH A SLIGHT INCREASE IN VERTICAL SHEAR FORECAST THROUGH THE
   EVENING. AS A RESULT...INSTABILITY AND SHEAR WILL LIKELY BE MORE
   THAN SUFFICIENT FOR SUPERCELL DEVELOPMENT. 850 TO 500 MB LAPSE RATES
   ARE FORECAST TO EXCEED 7.0 C/KM WITH 500 MB HEIGHTS AND TEMPS
   FALLING DURING THE OVERNIGHT HOURS. THIS SHOULD BE FAVORABLE FOR
   LARGE HAIL WITH ANY SUPERCELLS THAT DEVELOP. IN ADDITION...STRONG
   LOW TO MID-LEVEL FLOW SHOULD RESULT IN RELATIVELY FAST STORM MOTION
   AND MAY ENHANCE THE THREAT FOR WIND DAMAGE WITH THE STRONGER STORMS.
   THE ISOLATED SEVERE THREAT MAY CONTINUE THROUGH LATE IN THE PERIOD
   DUE TO THE INCREASING ASCENT AND INSTABILITY REMAINING IN PLACE.
   
   ...SRN ATLANTIC COAST...
   THE TROPICAL PREDICTION CENTER KEEPS HURRICANE OPHELIA NEARLY
   STATIONARY OFF THE COAST OF SC THROUGH TODAY WITH A SLIGHT NWWD
   MOVEMENT EXPECTED TONIGHT. THIS COULD BRING A FEW RAINBANDS CLOSE TO
   THE IMMEDIATE COASTAL AREAS LATE IN THE PERIOD. FORECAST SOUNDINGS
   SUGGEST 0-1 KM SHEAR VALUES WILL EXCEED 40 KT WITH MUCAPE VALUES
   REACHING NEAR 2000 J/KG. THIS MAY BE SUFFICIENT FOR A FEW ROTATING
   CELLS AS RAINBANDS NEAR THE COASTAL SECTIONS. ALTHOUGH UNCERTAIN
   ATTM...IF STORMS CAN MOVE INLAND ACROSS THE COAST...A MARGINAL
   TORNADO THREAT MAY DEVELOP LATE TONIGHT.
   
   ..BROYLES/TAYLOR.. 09/11/2005
   
   ...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 1300Z