Severe Thunderstorm Warning 20, NWS Green Bay, WI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
330 PM CDT SAT MAY 10 2003

SPLIT FLOW WL CONT ACROSS NOAM DURING THE FCST CYCLE...BUT THE SWRN U.S.
TROF AND STG SRN STREAM JET WL WEAKEN. INTENSE CYCLONE WL TRACK ACRS THE
RGN DURING THE FIRST 36 HRS OF THE FCST...THEN QUIETER WX WL RETURN FOR
THE REST OF THE FCST CYCLE.

AT 20Z...SFC LOW HAD MOVED INTO NW MO AND WAS BEGINNING TO DEEPEN.
TORNADIC STORMS WERE DEVELOPING SWD FM THE LOW. MEANWHILE...ELEVATED
CONVECTION N OF THE SFC WARM FRONT WAS STARTING TO INCR IN COVERAGE...
BUT NONE OF THE STORMS IN THE ISENT LIFT ZONE WERE VERY IMPRESSIVE YET.
THE SE PART OF THE FCST AREA WAS STILL IN THE SLGT RISK OF SVR WX. THE
RISK OF SVR WL COME DURING THE EVENING IF ANY ELEVATED STORMS BECOME STG
ENOUGH TO PRODUCE LARGE HAIL. IF SFC WARM FRONT CAN WORK INTO OR CLOSE
ENOUGH TO THE RGN...THERE COULD BE A RISK OF DAMAGING WINDS LATE TNGT.
TIME OF DAY WL BE EXACTLY OPPOSITE OF IDEAL FOR A WIND EVENT...BUT
DYNAMICS OF INCOMING SYSTEM COULD OVERRIDE ALL OTHER FACTORS.

EXPECT PCPN TO INCR AND OVERSPREAD THE RGN THIS EVENING AND CONT
OVERNIGHT. 12Z MODELS AS WELL AS LATEST STLT IMAGERY SUGGEST THAT COMMA
HEAD IN UPR DEFORMATION ZONE WL SET UP ACRS N-C WI. THAT COULD LEAD TO
VERY HEAVY RAINFALLS THERE. SOMEWHAT LOWER TOTALS EXPECTED IN C-NE WI...
BUT RIVERS IN C WI REACT MORE QUICKLY AND WERE ALREADY HIGH. SO...WENT
WITH FLOOD WATCH FOR LATE TNGT THROUGH SUN NGT. THE SECOND HALF OF THE
WATCH PRIMARILY FOR THE EXPECTED RIVER FLOODING WHICH WL LAG THE PCPN.

STG WINDS ALSO A CONCERN. MAIN NEGATIVE IS THE FACT THAT THE SFC LOW WL
TRACK RIGHT ACRS THE FCST AREA. THE NW PART OF THE AREA WL BE ON THE SE
EDGE OF THE STG N/NE WINDS...AND THE SE PART OF THE AREA WL BE ON THE NW
EDGE OF THE STG WLY WINDS BEHIND THE COLD FRONT/OCCLUSION. GRADIENT IS
THE TIGHTEST AND WINDS COULD BE THE STRONGEST LATER SUN AS SYSTEM
DEPARTS...THOUGH IT SEEMS WINDS NEVER GET AS QUITE AS STG IN AREAS
DIRECTLY ALONG THE STORM TRACK. WENT WITH WINDY WORDING IN THE FCST...
BUT HELD OFF ON WIND ADVISORY.

STILL NEED TO WATCH TO MAKE SURE THAT PCPN STAYS ALL LIQUID AS RAPIDLY
DEEPENING UPR SYSTEM CROSSES THE AREA LATE TNGT/EARLY SUN. THIS IS THE
TYPE OF RAPIDLY DEEPENING SYSTEM THAT COULD GENERATE ENOUGH DYNAMIC
COOLING TO GET PCPN TO AT LEAST MIX WITH WET SNOW. HOWEVER...ALL
INDICATIONS ARE THAT BOUNDARY LAYER TEMPS WL REMAIN WARM ENOUGH TO KEEP
PCPN ALL LIQUID EVEN IF TEMPS ALOFT CRASH WITH THE ARRIVAL OF THE
INTENSE LIFT/DEEPENING UPR SYSTEM.

CHC OF LINGERING SHOWERS WITH SLOWLY DIMINISHING WINDS EXPECTED MON NGT-
TUE. NEXT CHC OF PCPN WL BE WED. MED RANGE MODELS NOT IN GOOD AGREEMENT.
NCEP MED RANGE FCSTRS GOING WITH THE ECMWF...WHICH SHOWED A MUCH WEAKER
SHRTWV CROSSING THE AREA. THE 12Z GFS TRENDED IN THAT DIRECTION. WENT
WITH A CHC OF SHOWERS WED.

NRN STREAM EXPECTED TO STRENGTHEN AND BECOME DOMINANT LATE THIS WK AND
INTO THE UPCOMING WEEKEND. WLY UPR FLOW WITH THE NRN STREAM WELL N OF
THE AREA SHOULD ALLOW FOR WARMER WX FOR THE END OF THE WEEK AND INTO THE
START OF NEXT WEEKEND.

COORD W MKE AND MQT.

.GRB...FLOOD WATCH LATE TONIGHT THROUGH SUNDAY NIGHT
       WIZ005-010>013-018>021-030-031-035>037-073-074-

SKOWRONSKI/KURIMSKI
WWW.CRH.NOAA.GOV/GRB

WIZ005-010>013-018>022-030-031-035>040-045-048>050-073-074-111645-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREEN BAY WI
1145 AM CDT SAT MAY 10 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH-CENTRAL AND NORTHEAST
WISCONSIN.

.DAY ONE...THIS AFTERNOON AND TONIGHT

AS A DEEPENING LOW PRESSURE SYSTEM APPROACHES WISCONSIN...SHOWERS AND
THUNDERSTORMS WILL BE ON THE INCREASE AND WILL BECOME MORE NUMEROUS
TONIGHT. TONIGHT THERE IS A SLIGHT RISK FOR SEVERE THUNDERSTORMS...A FEW
OF THE STORMS COULD PRODUCE LARGE HAIL AND DAMAGING WINDS. LOCATIONS
SOUTH OF A LINE FORM STEVENS POINT TO GREEN BAY WILL BE MOST AT RISK FOR
SEVERE WEATHER.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

RAIN WITH ISOLATED THUNDERSTORMS WILL CONTINUE OVER THE REGION SUNDAY
AS THE INTENSE LOW PRESSURE SYSTEM TRACKS OVER THE REGION.  WHILE SEVERE
STORMS ARE NOT EXPECTED...THEIR IS THE POTENTIAL FOR HEAVY RAINFALL DUE
TO THE SLOW MOVEMENT OF THE STORM SYSTEM.  DURING THE PERIOD FROM
SATURDAY NIGHT TO SUNDAY EVENING...TOTAL RAINFALL AMOUNTS COULD RANGE
FROM 2 TO 3 INCHES FOR PARTS OF NORTH-CENTRAL AND CENTRAL WISCONSIN...
WITH 1 TO 2 INCHES POSSIBLE OVER NORTHEAST WISCONSIN.

IN ADDITION...AS THE LOW DEPARTS LATER SUNDAY INTO SUNDAY NIGHT...
NORTHWEST WINDS WILL INCREASE TO 20 TO 30 MPH WITH GUSTS TO 40 MPH
SUNDAY AFTERNOON AND EVENING.  THE WINDY CONDITIONS WILL CONTINUE
INTO MONDAY MORNING.  FOR MARINE INTERESTS...HIGH WAVES WILL DEVELOP
SUNDAY BEFORE SUBSIDING LATER MONDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED LATER THIS AFTERNOON AND TONIGHT.
RAINFALL REPORTS WILL BE APPRECIATED AND ANY RIVER OR URBAN FLOODING
SHOULD BE REPORTED.

KURIMSKI
WWW.CRH.NOAA.GOV/GRB