SPC AC 171641
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1141 AM CDT SAT APR 17 2004
   
   VALID 171630Z - 181200Z
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 30 N
   JHW 30 ENE PIT 25 S ZZV 10 SSW LAF 30 NE DSM 15 ENE OFK 55 SSE 9V9
   35 NNE HON 10 NNW STC 30 SW IMT APN.
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 25 NNE
   GCK 45 E DDC 15 E GAG 45 SE CDS 50 ENE BGS 20 WSW BGS 45 WSW LBB 40
   W AMA 10 N EHA 25 NNE GCK.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 55 NNE ISN 30 WNW P24
   55 NE BIS 25 SSE GFK 50 WNW HIB 20 N ELO ...CONT... 20 E PWM 10 SW
   BAF 20 NNW EWR 25 SSE MGW 15 SSE LUK 15 SW BMG 25 SSW HUF 10 NNE SPI
   35 NE IRK 25 SSW LWD 10 SSW EMP 25 ESE CSM 55 NNE ABI 30 ENE SJT 15
   NNW DRT ...CONT... 25 SE FHU 80 NW TCS 15 E GUP 75 NW GUP 30 NE GCN
   50 ESE EED 20 E TRM 35 S RAL 15 WNW PRB 35 E UKI 10 SSE MFR 55 SE
   EUG 15 SSE DLS 30 W LWS 45 W GTF 65 NW GGW.
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE MID MO RIVER VALLEY
   INTO THE SRN/WRN GREAT LAKES....
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER THE SRN HIGH PLAINS...
   
   ...SYNOPSIS...
   MID/UPPER LEVEL TROUGH NOW OVER CA WILL CONTINUE EJECTING NEWD INTO
   THE CENTRAL ROCKIES THROUGH THE PERIOD...WITH ASSOCIATED MID LEVEL
   JET NOSING ACROSS THE CENTRAL HIGH PLAINS BY LATE TONIGHT.  IN
   RESPONSE...SLY LLJ WILL INCREASE ACROSS THE CENTRAL PLAINS LATER
   TODAY AND TONIGHT AND SUSTAIN GRADUALLY MOISTENING WARM SECTOR OVER
   THE SRN AND CENTRAL PLAINS STATES.  AT THE SURFACE...OUTFLOW FROM
   OVERNIGHT MCS CURRENTLY EXTENDS FROM SRN IA ACROSS NRN IL AND INTO
   NRN IND/SERN LOWER MI THIS MORNING...WITH MORE PRONOUNCED COLD FRONT
   RUNNING FROM NRN LOWER MI INTO CENTRAL WI/SRN MN.  OUTFLOW BOUNDARY
   MAY ERODE DURING THE DAY...THOUGH EACH OF THESE SURFACE FEATURES MAY
   AID IN CONVECTIVE DEVELOPMENT DURING THE PERIOD.  FARTHER SOUTH AND
   WEST...SURFACE LOW IS EXPECTED TO DEVELOP OVER THE CENTRAL HIGH
   PLAINS AND BEGIN DEEPENING AS IT MOVES NEWD INTO SD LATER TONIGHT. 
   DRY LINE IS EXPECTED TO BECOME BETTER DEFINED THIS AFTERNOON SOUTH
   OF THIS LOW IN NERN CO ACROSS THE OK PANHANDLE AND INTO WRN TX.
   
   ...GREAT LAKES REGION...
   AFOREMENTIONED SURFACE BOUNDARIES WILL LIKELY REMAIN STALLED OR LIFT
   SLOWLY NWD BEFORE CONSOLIDATING INTO A WELL DEFINED WARM FRONT
   TONIGHT FROM SERN SD INTO CENTRAL/SRN WI AND LOWER MI. OUTFLOW
   BOUNDARY WILL DELINEATE NERN EXTENT OF MODEST BOUNDARY LAYER
   MOISTURE...WITH SURFACE DEW POINTS IN THE MID 50S TO LOWER 60S.  AS
   AFTERNOON HEATING DESTABILIZES THE AIRMASS...THIS SHOULD BE
   SUFFICIENT FOR MODERATE INSTABILITY ALONG SRN EXTENT OF MODEST WNWLY
   MID LEVEL FLOW.  SHEAR AND INSTABILITY WILL SUPPORT A THREAT OF
   STRONG TO SEVERE THUNDERSTORMS IN THE FORM OF MULTICELL CLUSTERS AND
   SUPERCELLS...ONCE CONVECTION DEVELOPS THIS AFTERNOON AND CONTINUE
   INTO THE EVENING.
   
   OTHERWISE...INCREASING LLJ LATER TONIGHT WILL LIKELY SUPPORT ONE OR
   MORE SEVERE MCSS MOVING ENEWD NORTH OF THE WARM FRONT EARLY SUNDAY
   MORNING.  STORMS WILL BE ELEVATED...HOWEVER FORECAST SOUNDINGS
   INDICATE SUFFICIENT LAPSE RATES AND MODERATE ELEVATED INSTABILITY
   FOR LARGE HAIL.
   
   ...CENTRAL PLAINS INTO THE NRN MS RIVER VALLEY...
   THOUGH STEEP LAPSE RATES WILL SUPPORT MODERATE TO STRONG INSTABILITY
   ACROSS THE WARM SECTOR TODAY...THEY WILL ALSO MAINTAIN A CAPPING
   INVERSION.  APPEARS BEST POTENTIAL FOR ISOLATED SEVERE THUNDERSTORMS
   THIS AFTERNOON WILL OCCUR NEAR THE SURFACE/OUTFLOW BOUNDARIES ACROSS
   CENTRAL/NRN IA INTO NERN NEB/SERN SD LATE IN THE DAY...LIKELY AROUND
   00Z.  FORECAST OF STRONG DEEP LAYER SHEAR AND INSTABILITY ACROSS
   THIS REGION SUGGEST ANY STORMS WHICH CAN BREAK THE CAP WILL BECOME
   QUITE STRONG AND ORGANIZE INTO SUPERCELLS RATHER QUICKLY.  THIS
   ACTIVITY MAY EVOLVE INTO A SEVERE MCS ALONG NOSE OF STRONG LLJ INTO
   NRN IA/SRN AND CENTRAL MN DURING THE EVENING WHICH WILL TRACK ENEWD
   TOWARDS THE WRN GREAT LAKES OVERNIGHT. ADDITIONAL MCS MAY FORM LATE
   TONIGHT AS NOSE OF MID LEVEL JET AND RIGHT ENTRANCE REGION OF UPPER
   LEVEL JET DEVELOP OVER SERN SD/SWRN MN AS INDICATED BY 12Z
   ETA...WHICH WOULD OCCUR ALONG AXIS OF STRONG ELEVATED INSTABILITY
   AND DEEP LAYER SHEAR.  THOUGH LARGE HAIL...SOME OF WHICH COULD BE
   QUITE LARGE...WILL ACCOMPANY STORMS THROUGH THE PERIOD...DAMAGING
   WINDS AND A FEW TORNADOES COULD OCCUR WITH ANY DIURNAL/WARM SECTOR
   STORMS INTO THE MID EVENING.
   
   ...SRN HIGH PLAINS...
   MODELS HAVE BEEN CONSISTENT IN BRINGING ILL-DEFINED SRN STREAM
   SHORTWAVE TROUGH ACROSS THE SRN HIGH PLAINS LATER TODAY AND THIS
   EVENING...AND IN DEVELOPING QPF ALONG THE DRY LINE IN ASSOCIATION
   WITH THIS FEATURE.  LATEST VISIBLE SUGGESTS CLOUDS OVER WRN TX MAY
   NOT BE AS DENSE AS EARLIER THOUGHT...SUGGESTING CAP MAY WEAKEN AS AN
   AXIS OF MODERATE INSTABILITY FORMS ALONG AND EAST OF THE DRY LINE. 
   THOUGH STORMS DEVELOPING LATER TODAY AND THIS EVENING WILL LIKELY BE
   HIGH-BASED DUE TO MARGINAL BOUNDARY LAYER MOISTURE AND STRONG
   HEATING...LARGE LAPSE RATES AND STRENGTH OF SHEAR SUGGEST A THREAT
   OF SUPERCELLS/MULTICELL CLUSTERS PRODUCING LARGE HAIL AND DAMAGING
   WINDS.
   
   ..EVANS.. 04/17/2004
   
   ...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 2000Z