SPC AC 160555
 
   STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK 
   DAY 1 CONVECTIVE OUTLOOK...REF AWIPS GRAPHIC PGWE46 KWNS. 

   VALID 161200Z - 171200Z 

   THERE IS A HIGH RISK OF SVR TSTMS THIS EVENING AND TONIGHT ACROSS 
   MOST OF MINNESOTA...WESTERN WISCONSIN...NORTHWESTERN IOWA... 
   SOUTHEASTERN SOUTH DAKOTA...AND A SMALL PART OF NORTHEAST NEBRASKA. 
   THE HIGH RISK AREA IS TO THE RIGHT OF A LINE FROM 35 NE ELO 55 WSW 
   IWD 30 NNW LSE 40 NNW DSM 25 WSW OMA 15 E BUB 35 NNE ATY 80 N GFK.
 
   SURROUNDING THE HIGH RISK AREA...THERE IS A SLGT RISK OF SVR TSTMS 
   TO THE RIGHT OF A LINE FROM 35 NW ANJ 15 SE MBL 15 E CGX 25 NNW UIN 
   35 SSE TOP 35 SE RSL 20 WSW HLC 35 NNE LBF 45 NE ANW 15 NE ABR 65 
   NW DVL. 

   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 35 WNW CTY 25 NE CSG 
   HSV 20 NE UOX 20 S GLH 30 SE SHV 10 ESE SAT 50 SSE DRT ...CONT... 
   25 SSW P07 65 WSW SPS 15 ESE GAG 40 NNE EHA 20 NE RTN 25 NW ABQ 60 
   NW GUP 30 SSE 4HV 35 SW VEL 25 SE RWL 15 SE AIA 40 NW VTN 35 NE MBG 
   50 N MOT. 

   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 60 ENE 63S 55 SSW 
   S80 65 SSE BNO 10 WNW LMT 45 NNW 4BK.
 
   PARAMETERS APPEAR TO BE COMING TOGETHER FOR A SIGNIFICANT SEVERE 
   WIND EVENT ACROSS PORTIONS OF THE UPPER MISSISSIPPI VALLEY ON 
   TUESDAY. STRONG UPPER LEVEL TROUGH...NOW OVER THE GREAT BASIN... 
   WILL SHIFT EASTWARD INTO THE PLAINS. THE ACCOMPANYING INTENSE 
   SURFACE LOW WILL CROSS INTO THE NORTHERN PLAINS AND INTO SOUTHERN 
   PORTIONS OF ONTARIO BY THE END OF THE PERIOD. 

   ...NORTHERN PLAINS/UPPER MISSISSIPPI VALLEY... 
   LATEST ETA GUIDANCE IS A BIT FASTER THAN THE PREVIOUS TWO RUNS IN 
   BRINGING THE UPPER LEVEL TROUGH OUT OF THE ROCKIES AND INTO THE 
   PLAINS THIS PERIOD. LATEST SURFACE OBSERVATIONS SHOW PLENTY OF LOW 
   LEVEL MOISTURE IN PLACE THROUGHOUT THE PLAINS INTO THE UPPER 
   MISSISSIPPI VALLEY. CURRENT DEWPOINTS REMAIN WELL INTO THE 50S AND 
   LOW 60S ACROSS THE NORTH CENTRAL PARTS OF THE NATION. AS THE 
   SURFACE SYSTEM CONTINUES TO DEVELOP/STRENGTHEN...SOUTHERLY LOW 
   LEVEL FLOW SHOULD REMAIN IN THE 15 TO 25 KNOT RANGE...AND THIS WILL 
   HELP KEEP THE INFLUX OF MOISTURE UNINTERRUPTED AHEAD OF THE COLD 
   FRONT. STRONG WARMING SHOULD ALLOW SURFACE TEMPERATURES TO CLIMB 
   INTO THE LOW TO MID 80S. AS THE UPPER TROUGH NEARS THE REGION... 
   MID LEVEL TEMPERATURES WILL COOL SEVERAL DEGREES. THE COMBINATION 
   OF THE LOW LEVEL WARMING AND MID LEVEL COOLING SHOULD ALLOW THE AIR 
   MASS TO BECOME VERY UNSTABLE DURING THE AFTERNOON HOURS.
 
   FORECAST SOUNDINGS THROUGHOUT THE NORTHERN PLAINS/UPPER MISSISSIPPI 
   VALLEY INDICATE LOW TO MID LEVEL FLOW WILL BECOME NEARLY 
   UNIDIRECTIONAL...AND MERIDIONAL. MID LEVEL SPEEDS ARE FORECAST TO 
   BE IN THE 50 TO 60 KNOT RANGE...AND THIS WOULD BE MORE THAN ENOUGH 
   FLOW TO SUPPORT THE POTENTIAL FOR NUMEROUS SEVERE THUNDERSTORMS 
   WHICH WILL HAVE THE ABILITY TO GENERATE VERY STRONG...WIDESPREAD 
   DAMAGING WIND GUSTS.
 
   STORMS SHOULD BEGIN TO DEVELOP AHEAD OF THE ADVANCING UPPER TROUGH 
   AND ACCOMPANYING COLD FRONT DURING THE LATE AFTERNOON AND EVENING 
   HOURS /LIKELY IN THE 21Z TO 00Z TIME FRAME/. GIVEN THE 
   UNIDIRECTIONAL NATURE OF THE WIND FIELDS AND THE STRONG INSTABILITY
   ...THE ACTIVITY SHOULD QUICKLY EVOLVE INTO LINES AND BOWS AS THEY 
   MOVE RAPIDLY NORTHWARD ACROSS PORTIONS OF NORTHEASTERN NEBRASKA AND 
   IOWA INTO MINNESOTA AND WESTERN WISCONSIN OVERNIGHT.
 
   A PUBLIC SEVERE WEATHER OUTLOOK WILL BE ISSUED BY 10Z. 

   ...CENTRAL/SOUTHERN PLAINS... 
   ISOLATED TO WIDELY SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP 
   ALONG AND AHEAD OF A DRYLINE WHICH IS FORECAST TO MOVE EASTWARD 
   THROUGH THE CENTRAL AND SOUTHERN PLAINS. LOW LEVEL CONVERGENCE IN 
   THE VICINITY OF THE BOUNDARY SHOULD INCREASE SUFFICIENTLY TO HELP 
   BREAK THROUGH THE CAP...BUT WITH THE UPPER LEVEL TROUGH EXPECTED TO 
   LIFT NORTHEAST OF THE AREA...THE STRONGEST FORCING IS EXPECTED TO 
   REMAIN FROM KANSAS NORTHWARD TO THE CANADIAN BORDER.
 
   RAINFALL FROM LATE LAST WEEK COMBINED WITH THE INCREASING SOUTHERLY 
   LOW LEVEL FLOW HAS MAINTAINED ABUNDANT LOW LEVEL MOISTURE 
   THROUGHOUT THE PLAINS REGION. AFTERNOON TEMPERATURES WILL LIKELY 
   CLIMB WELL INTO THE 70S AND 80S...WITH A FEW AREAS POSSIBLY NEARING 
   90. FORECAST SOUNDINGS SHOW MOST UNSTABLE CAPE VALUES IN EXCESS OF 
   2500 J/KG. FLOW IN THIS ARE WILL LIKELY EXHIBIT MORE OF A VEERING 
   PROFILES IN THE LOW TO MID LEVELS...SUGGESTING AN INCREASED 
   POTENTIAL FOR SUPERCELLS. HOWEVER...THE STRENGTH OF THE CAP SHOULD 
   LIMIT THE COVERAGE OF THUNDERSTORMS TO ISOLATED TO PERHAPS WIDELY 
   SCATTERED. THE LATEST MODEL GUIDANCE /ETA WITH KAIN-FRITSCH 
   CONVECTION/ INDICATES STORMS WILL LIKELY BE RATHER SHORT LIVED 
   FARTHER SOUTH ALONG THE DRYLINE. LARGE HAIL AND PERHAPS AN 
   ISOLATED TORNADO OR TWO IS POSSIBLE...ESPECIALLY FROM SOUTHEASTERN 
   NEBRASKA SOUTHWARD INTO NORTHERN AND PERHAPS CENTRAL KANSAS. 
   STORMS SHOULD DECREASE IN INTENSITY AFTER 00Z WITH THE LOSS OF 
   HEATING. 

   ..REHBEIN.. 04/16/02
   
   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED FOR 1300Z