SPC AC 211248
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0748 AM CDT SAT MAY 21 2005
   
   VALID 211300Z - 221200Z
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM CMX 35
   E AUW DBQ 25 SW BRL 15 NNE TBN 10 SSE SGF 30 WNW JLN HUT 45 NNE DDC
   15 NW HLC 25 NNW GRI 30 SW YKN ATY FAR DVL 80 NNW DVL.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 25 SE ORF 30 WSW ORF
   LYH 25 ENE SSU 30 W MGW YNG 25 NNE ERI.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM EFK LEB ORH 10 WSW
   BID.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 65 NE APN 15 N FNT 50
   N SDF 25 NNW DYR 50 SW ARG 45 NNW HOT 40 SSW TUL 35 NW PNC 30 N LBL
   30 ESE RTN 45 SW PUB 40 NW COS 15 NW FCL 15 ESE CYS SNY 40 SSW ANW
   30 SW 9V9 35 NW MBG 30 SSE DIK 25 ENE GDV 50 N GGW.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 30 SE MOB CEW 30 SW
   ABY 30 NNE AYS 30 SSW CRE.
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF THE UPR MS VLY
   SWD INTO THE MID/LWR MO VLY...
   
   ...SYNOPSIS...
   DOMINANT SWRN STATES RIDGE WILL UNDERGO A TEMPORARY SUPPRESSION THIS
   PERIOD AS POTENT SHORTWAVE IMPULSE NOW ENTERING THE NRN HI PLNS
   CONTINUES E ACROSS ND. THE SYSTEM WILL BE FORCED TO TURN SOMEWHAT 
   S OF E LATER IN THE PERIOD AS BLOCK HOLDS FIRM OVER NRN QUEBEC.
   
   AT THE SFC...LOW NOW DEVELOPING OVER CNTRL ND SHOULD SUBSTANTIALLY
   DEEPEN AND OCCLUDE AS IT MOVES TOWARD LK WINNIPEG LATER TODAY/EARLY
   SUNDAY.  NRN PART OF ASSOCIATED COLD FRONT WILL ACCELERATE E INTO
   WRN MN BY THIS EVENING...AND INTO WI/NW IL BY SUNDAY MORNING.  THE
   MORE SRN PORTION OF THE FRONT SHOULD MOVE MORE SLOWLY SE ACROSS THE
   MID AND LWR MO VLYS.  BLOCKING PATTERN WILL LIKELY KEEP N/S WARM
   FRONT NEARLY STATIONARY OVER THE UPR MS VLY...ALTHOUGH THERE SHOULD
   BE SOME NEWD ADVANCE OF THE BOUNDARY ACROSS MO.
   
   ...CNTRL PLNS TO UPR MS VLY...
   MCS WITH EMBEDDED MCV NOW OVER NERN ND HAS MOVED BEYOND LOW LEVEL
   INSTABILITY AXIS.  THE SYSTEM SHOULD WEAKEN AS IT HEADS ENE TO THE
   INL AREA LATER THIS MORNING.  BAND OF WARM ADVECTION STORMS
   EXTENDING S FROM THE MCV INTO IA SHOULD SPREAD SLOWLY E WILL LITTLE
   CHANGE IN INTENSITY.
   
   SATELLITE LOOPS SUGGEST THAT SHORTWAVE DISTURBANCE OFF THE WA/ORE
   CST HAS UNDERGONE STRONG DEEPENING OVERNIGHT.  THIS...IN TURN...
   SHOULD LEAD TO CONTINUED AMPLIFICATION OF DOWNSTREAM NRN PLNS
   IMPULSE.  AS A RESULT...STOUT CAP WILL LIKELY PERSIST...AND MAY EVEN
   STRENGTHEN...OVER THE CNTRL PLNS/UPR MS VLY REGION S OF ASSOCIATED
   JET MAX CROSSING THE NRN PLNS.
   
   SEWD ADVANCE OF NRN PLNS COLD FRONT...AND PRECIPITATION INTO DRY CP
   AIR MASS ADVECTING NWWD FROM THE MID MS VLY...WILL KEEP AXIS OF
   BOUNDARY LAYER MOISTURE OVER SLIGHT RISK AREA VERY CONFINED THROUGH
   THE PERIOD.  AVERAGE DEWPOINTS SHOULD...NEVERTHELESS... RISE INTO
   THE UPPER 50S LATER TODAY OVER THE ERN DAKOTAS/WRN MN. LOWER 60S
   WILL BE POSSIBLE ALONG A NARROW AXIS EXTENDING SWD ACROSS CNTRL/ERN
   NEB INTO KS.
   
   STRONG HEATING WILL OCCUR IN WAKE OF MORNING CONVECTION FROM THE RED
   RVR VLY SWD INTO ERN NEB/WRN IA.  COUPLED WITH CONVERGENCE ALONG
   COLD FRONT AND INCREASING FORCING FOR ASCENT ASSOCIATED WITH
   APPROACHING UPPER IMPULSE...EXPECT THAT RENEWED STORM DEVELOPMENT
   WILL EVENTUALLY OCCUR FROM N TO S ALONG THE BOUNDARY LATER THIS
   AFTERNOON INTO TONIGHT.
   
   AMPLE /35-40 KT/ DEEP W TO NWLY SHEAR WILL EXIST FOR SUPERCELLS IN
   SLIGHT RISK AREA.  WHILE LINEAR FORCING OF COLD FRONT WILL BE
   STRONG...ESPECIALLY IN MN...SHEAR VECTORS WILL BE ORIENTED NEARLY
   PERPENDICULAR TO THE BOUNDARY. THUS...POTENTIAL WILL EXIST FOR A
   FEW LONGER-LIVED DISCRETE STORMS.  THIS POTENTIAL MAY BE GREATEST
   DURING THE EARLY EVENING ACROSS NE NEB/NW IA...AS CAP IS BREACHED
   IN REGION OF MAXIMUM SURFACE-BASED INSTABILITY /MUCAPE TO 3000 J
   PER KG/.  GIVEN THE DEGREE OF INSTABILITY AND SHEAR...A CONDITIONAL
   THREAT WILL EXIST FOR VERY LARGE HAIL/HIGH WIND AND POSSIBLE
   TORNADOES.
   
   ADDITIONAL STORMS SHOULD FORM IN ERN NEB/IA AND NRN MO LATER THIS
   EVENING AS SEWD TURN OF NRN PLNS IMPULSE LOWERS HEIGHTS ACROSS
   REGION.  COUPLED WITH STRENGTHENING LOW LEVEL JET AND MOISTURE
   TRANSPORT...THIS ACTIVITY SHOULD EVOLVE INTO A FORWARD PROPAGATING
   MCS THAT COULD EXTEND A RISK FOR HIGH WIND S/SW INTO CNTRL AND SRN
   PARTS OF KS/MO EARLY SUNDAY.
   
   ..NRN/ERN FL...
   SCATTERED STORMS EXPECTED TO DEVELOP INVOF RESIDUAL COLD FRONT
   OVER THE NRN PART OF THE STATE AND ALONG SEA BREEZE BOUNDARIES.  E
   COAST SEA BREEZE SHOULD STAY CLOSE TO SHORE GIVEN PREVAILING
   PREFRONTAL WLYS IN THE BOUNDARY LAYER. LOW TO MIDLEVEL SHEAR WILL
   BE WEAK....AND MORNING RAOBS SHOW RATHER LIMITED LOW LEVEL
   INSTABILITY/LAPSE RATES.  THUS...THREAT FOR ORGANIZED SEVERE STORMS
   APPEARS LOW.  HOWEVER...A FEW STRONG-SEVERE MULTICELLS WITH RISK OF
   DAMAGING DOWNBURSTS MAY DEVELOP DURING LATE MORNING INTO AFTERNOON
   INVOF BOUNDARY INTERSECTIONS AS AVERAGE MLCAPE RISES TO AROUND 1500
   J/KG.
   
   ..CORFIDI/TAYLOR.. 05/21/2005
   
   ...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

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