SPC AC 101254
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0754 AM CDT WED SEP 10 2003
   
   VALID 101300Z - 111200Z
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 25 NE
   BGS 35 NNE MAF 55 WSW LBB 20 NW LBF 45 NNE VTN 50 ESE BIS 30 NNW JMS
   30 S GFK 35 SW BJI 40 WNW BRD 30 SW SPW 30 ESE BIE 35 NW PNC 30 NE
   LTS 25 NE BGS.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 55 SSW TUS 50 SE PHX
   15 NW PRC 55 SSE PGA 15 W 4HV 30 E U24 30 W MLD 50 NW LND 35 NNW CPR
   45 NNE 81V 50 NNW MOT ...CONT... 50 E INL 15 ESE MKT 40 N STJ 25 SW
   TUL 15 NW DAL 30 NE TYR 50 ESE HRO 50 NNW LAF 10 N DAY 15 S ANB 15 W
   PFN ...CONT... 65 SSE FMY 25 S PBI.
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE PLAINS
   STATES...
   
   ...SYNOPSIS...
   THE COMBINATION OF A STRONG UPPER RIDGE OVER THE ERN U.S./ERN CANADA
   AND STRONG WLY UPPER LEVEL PACIFIC FLOW NOSING INTO THE PACIFIC NW
   TODAY WILL SHARPEN THE TROUGH OVER THE WRN STATES...AS IT MOVES EWD
   TO OVER THE ROCKIES/HIGH PLAINS BY 12Z THURSDAY.  A STRONG SHORT
   WAVE TROUGH LIFTING NNEWD ACROSS THE NRN PLAINS AND A SECOND SHORT
   WAVE TROUGH MOVING INTO THE BASE OF THE MEAN TROUGH WILL BOTH
   SUPPORT CONVECTION ACROSS THE PLAINS STATES THIS PERIOD.
   
   ...PLAINS STATES...
   ONGOING CONVECTIVE COMPLEX ACROSS CENTRAL KS WILL CONTINUE TO MOVE
   NEWD ACROSS NERN KS/SRN NEB THIS MORNING AND DECREASE IN INTENSITY
   AS THE SLY 45-50 KT LLJ OVER THIS AREA WEAKENS.
   
   ELEVATED STORMS ACROSS NRN SD/SRN ND WILL CONTINUE TO LIFT NWD TODAY
   AS THE INITIAL SHORT WAVE TROUGH AND ASSOCIATED SURFACE LOW MOVE NWD
   OVER ND INTO SRN CANADA.  THIS SURFACE LOW IS PROGGED TO BE OVER
   CENTRAL/ERN ND BY 00Z WITH A TROUGH TRAILING SWWD THROUGH CENTRAL
   NEB TO AN AREA OF SURFACE CYCLOGENESIS OVER SERN CO.
   
   DESPITE CONVECTIVE DEBRIS ACROSS SD SWD TO KS...ENOUGH DECREASE IN
   CLOUDINESS THROUGH THE DAY WILL ALLOW FOR SUFFICIENT HEATING AIDING
   IN DESTABILIZATION WITHIN A MOIST AIR MASS.  AFTERNOON MLCAPE VALUES
   SHOULD RANGE FROM 1000 J/KG OVER ERN SD TO 2500 J/KG ACROSS SRN
   KS/NWRN OK.  AS THE WRN MEAN TROUGH MOVES EWD TODAY...SSWLY 50-60 KT
   MID-LEVEL FLOW WILL PERSIST FROM THE SRN ROCKIES TO THE CENTRAL/NRN
   PLAINS...SUPPORTING DEEP LAYER SHEAR FOR MULTICELL STORMS. 
   SUPERCELLS WILL BE MORE LIKELY FROM KS TO SD WHERE DEEP LAYER SHEAR
   WILL BE STRONGER.  CONVECTION IS EXPECTED TO DEVELOP ALONG THE
   SURFACE TROUGH BY LATE THIS AFTERNOON /22-00Z/ AS LOW-LEVEL
   CONVERGENCE INCREASES ALONG THIS BOUNDARY AND UPPER LEVEL DIFLUENCE
   OVER THE CENTRAL PLAINS AIDS IN SUSTAINING DEEP MOIST CONVECTION. 
   STRENGTHENING SLY LLJ OVER THE SRN/CENTRAL PLAINS LATER TODAY INTO
   THE EVENING WILL SUPPORT FAVORABLE LOW-LEVEL SHEAR FOR A TORNADO
   THREAT FROM MAINLY KS TO SD WHERE DISCRETE SUPERCELLS WILL BE
   POSSIBLE WITH INITIAL STORMS.  LARGE HAIL AND DAMAGING WINDS WILL
   ALSO BE A THREAT WITH THESE STORMS.  FORECAST SOUNDINGS SHOW DEEP
   LAYER SHEAR BECOMING ORIENTED PARALLEL TO THE SURFACE TROUGH THIS
   EVENING... SUGGESTING THE CONVECTIVE MODE WILL EVOLVE INTO A SQUALL
   LINE WITH DAMAGING WINDS BEING THE PRIMARY THREAT INTO THE OVERNIGHT
   PERIOD WITH LINE SEGMENTS/BOWS.
   
   ..PETERS/CROSBIE.. 09/10/2003
   
   ...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 1630Z