SPC AC 182356
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0656 PM CDT SUN APR 18 2004
   
   VALID 190100Z - 191200Z
   
   THERE IS A MDT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 30 SW
   FOD 20 S OMA 15 SSE LNK 25 S OLU 15 E YKN 25 E BKX 40 S AXN 20 SE
   BRD 45 WSW DLH 25 ESE DLH 15 ESE IWD 30 N RHI 10 WSW RHI 20 SSW EAU
   10 WSW MCW 30 SW FOD.
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM APN
   MSN 45 NNW OTM 30 SW LWD 15 WSW EMP ICT 25 WSW HUT 10 SSW RSL 25 ESE
   LBF 20 ESE MHN VTN 25 ESE ABR 35 E FAR 10 ENE BJI 35 ESE INL.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 40 NE HVR 45 NNE LWT
   50 SE LWT 30 E BIL 30 NW 4BQ 35 SE SDY 25 WNW MOT 65 NNW DVL
   ...CONT... 75 WNW MRF 40 NW HOB 45 ENE DHT 35 SW HLC 35 SSW MCK 45
   NW GLD 25 NNW LIC 30 SSE DEN 55 W COS 35 S GUC 15 ESE CEZ 25 SE U17
   60 WNW 4HV 50 S ENV 30 NNW BAM 40 SE BNO 50 ENE EUG 25 ESE SLE 45
   SSE SEA 65 ENE BLI.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 55 NNE BML 15 SE LCI
   15 ESE EWB.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 20 ENE ISP 15 N MFD
   BLV 40 WNW FYV 55 SE DRT.
   
   ...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF NRN WI...SE
   MN...NW IA...ERN NEB...FAR SE SD...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF
   KS...NEB...SD...MN...WI...IA...FAR NW MO...
   
   ***THIS OUTLOOK IS BEING AMENDED BECAUSE THE SQUALL-LINE IS
   DEVELOPING FARTHER SOUTH THAN PREVIOUSLY EXPECTED. IN ADDITION...THE
   SLIGHT RISK IS BEING EXTENDED SWD ACROSS KS.
   
   
   ...POTENTIAL EXISTS FOR A FEW SIGNIFICANT SEVERE REPORTS ACROSS THE
   UPPER MS VLY LATER THIS AFTERNOON AND EVENING...
   
   ...CNTRL/NRN MN-CNTRL GREAT LAKES REGION...
   VAPOR IMAGERY SHOWS VIGOROUS MIDLEVEL IMPULSE MOVING NEWD INTO THE
   NEB PNHDL...EN ROUTE TO THE UPPER MS VLY LATER TONIGHT.  18Z SURFACE
   CHART INDICATES A SURFACE LOW IS BEGINNING TO DEEPEN...WITH 994 MB
   CENTER LOCATED VCNTY KATY.  WARM FRONT HAS JUMPED NORTH...SITUATED
   FROM THE LOW EWD THROUGH CNTRL MN TO NRN WI.  WARM SECTOR HAS
   RAPIDLY DESTABILIZED OWING TO UNABATED HEATING...BOUNDARY LAYER DEW
   POINTS NEAR 60F AND STEEP MID TROPOSPHERIC LAPSE RATES...ALL
   CONTRIBUTING TO MLCAPES OF 1500-2000 J/KG.
   
   STRONGEST PRESSURE FALLS EXIST JUST NORTH OF KMSP...AND THE LOW
   SHOULD TRACK ALONG THE WARM FRONT THROUGH CNTRL MN TO NWRN WI BY
   LATE EVENING.  PRIND THAT SURFACE BASED INITIATION WILL OCCUR IN
   WCNTRL MN BY 22Z AND EXPAND EWD ALONG/NORTH OF THE WARM FRONT INTO
   ECNTRL/NERN MN AND NWRN WI BY LATE EVENING.
   
   STRONG SLY FLOW AHEAD OF THE LOW BENEATH SWLY H5 FLOW OF 60-70 KTS
   WILL RESULT IN VERTICAL SHEAR SUPPORTIVE FOR SUPERCELLS.  GIVEN WARM
   FRONT ORIENTATION WITH RESPECT TO THE MEAN SHEAR...CELLS ARE APT TO
   REMAIN DISCRETE THE LONGEST FROM CNTRL MN EWD. LOW LEVEL STORM
   RELATIVE HELICITY ALONG THIS FRONT WILL MAINTAIN THE THREAT OF A FEW
   TORNADOES...A COUPLE OF WHICH MAY BE STRONG.  MOREOVER...MAGNITUDE
   OF VERTICAL SHEAR...INSTABILITY AND STEEP LAPSE RATES SUGGEST THAT
   VERY LARGE HAIL AND SIGNIFICANT DAMAGING WINDS ARE POSSIBLE.
   
   LATER THIS EVENING/OVERNIGHT...TSTMS ARE EXPECTED TO CONGEAL INTO
   ONE OR MORE MCS/S AND BECOME MORE LINEAR WITH TIME AS THEY MOVE
   ENEWD INTO UPPER MI AND PERHAPS EXTREME NRN LOWER MI WITH THE THREAT
   OF LARGE HAIL AND DAMAGING WINDS.  IN ADDITION TO THE FORWARD
   PROPAGATING NATURE TO THE ACTIVITY...CELLS MAY TEND TO BACKBUILD
   SWWD INTO CNTRL/SRN MN FOR A WHILE TONIGHT AS THE MEAN FLOW BECOMES
   MORE UNIDIRECTIONAL AND STRONGEST INSTABILITY POOL REMAINS UPSTREAM.
   
   
   
   ...ERN SD INTO NRN/CNTRL NEB INTO NWRN IA/SWRN MN...
   COLD FRONT CONTINUES TO SURGE SEWD INTO VERY WARM AIR MASS.  TSTMS
   HAVE DEVELOPED IN THE DRY SLOT FROM NRN NEB...AND ATOP THE DEEPENING
   COLD DOME OVER CNTRL SD.  PRIND THAT STORMS WILL DEVELOP AND BECOME
   LINEAR RATHER QUICKLY FROM CNTRL/NERN NEB AND ERN SD AND MOVE ENEWD
   INTO NWRN IA AND SRN MN LATER THIS EVENING.  THE STORMS THAT DEVELOP
   ALONG THE COLD FRONT WILL HAVE THE THREAT FOR LARGE HAIL AND
   DAMAGING WINDS...WHILE STORMS NORTH IN THE COLDER AIR WILL LIKELY
   HAVE A GREAT LIKELIHOOD OF LARGE HAIL.
   
   ...ERN NY/WRN NEW ENGLAND...
   LONG-LIVED FORWARD PROPAGATING MCS HAS REMAINED STRONG WELL INTO THE
   AFTERNOON WITH HISTORY OF LARGE HAIL AND DAMAGING WINDS.  DOWNSTREAM
   BOUNDARY LAYER/WARM SECTOR HAS WARMED INTO THE UPPER 70S WITH
   DEWPOINTS IN THE 50S. GIVEN THAT REGION RESIDES ALONG SRN PERIPHERY
   OF THE WLYS...THERE IS NO REASON THAT TSTMS WILL NOT REMAIN STRONG
   AS THEY MOVE INTO THE HUDSON RVR VLY INTO WRN NEW ENGLAND WITH
   ATTENDANT HIGH WINDS/HAIL.  ACTIVITY SHOULD BEGIN TO WEAKEN AS IT
   MOVES TOWARD THE COAST THIS EVENING.
   
   ...KS SWD INTO SRN HIGH PLAINS...
   SUBTROPICAL JETLET MOVING NEWD INTO THE SRN PLAINS ARE AIDING IN
   ELEVATED TSTMS.  IT IS NOT LIKELY THAT STORMS WILL ROOT INTO THE
   BOUNDARY LAYER...BUT WILL MAINTAIN A LOW PROBABILISTIC THREAT OF
   DAMAGING WINDS/HAIL THROUGH THIS EVENING.
   
   ..BROYLES.. 04/18/2004
   
   ...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 0100Z