Severe Thunderstorm Warning 64, NWS Green Bay, WI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
845 PM CDT THU AUG 26 2004

.UPDATE...ISOLD SVR HAD DIMINISHED EARLIER THIS EVENING DUE TO LOSS OF
HEATING.  MAIN CONVECTION OVER IA NEAR REGION OF HIGHER CAPES AND OVER
FAR WRN MN INTO THE DKTS NEAR THE FRONT.  NEAR 02Z CONVECTION OVER CLARK
APPEARING TO HAVE A BOW STRUCTURE...SO FAR NO REPORTS BUT THIS LINE MAY
HAVE THE POTENTIAL OF SOME GUSTY WINDS.  WILL ADJUST ZONES FOR THIS
EVENING FOR TSRA TRENDS AND COVERAGE.

TH

DISCUSSION BELOW ISSUED THIS AFTERNOON.

.SHORT TERM...TNGT AND FRI. CONVECTIVE POTENTIAL STARTING TO BECOME A
BIT CLEARER. 18Z GRB RAOB CONFIRMED THAT VERY WARM TEMPS ARND 900 MB HAD
SPREAD EWD ACRS THE FCST AREA DURING THE MORNING. THAT WAS PROVIDING A
STG CAP AND INHIBITING CONVECTION. THAT CAPPING WAS LIKELY WEAKEST ACRS
THE FAR NW PART OF THE FCST AREA...SO EXPECT THAT AREA WL BE AT GREATEST
RISK OF TSTMS LATE THIS AFTN...WITH THE RISK SPREADING SEWD DURING THE
EVENING.

SOME FORCING TO BREAK THE CAP WAS OCCURRING OVER ERN MN/WRN WI WHERE WK
SFC BOUNDARY WAS PROVIDING SOME CONVERGENCE. CU ALSO STARTING TO DEVELOP
ACRS NE IA...BUT 18Z DVN SOUNDING ALSO HAD A STG CAP AND SUGGESTED THAT
WE WL NEED ADDITIONAL LARGE-SCALE FORCING TO HELP GET THINGS GOING. THE
18Z RUC SUGGESTED THAT IT WOULD TAKE UNTIL WELL INTO THE EVENING WHEN
THE NOSE OF UPR LEVEL JET PROPOGATES INTO THE RGN FOR CONVECTION TO
REALLY BLOSSOM ACRS THE AREA. THAT LOOKED QUESTIONABLE...HOWEVER...GIVEN
THE LOOK OF THE STLT IMAGERY BACK TO THE WEST. STILL THINK BEST BET WAS
THAT STORMS WL DEVELOP BTWEN 21Z-23Z W OF THE AREA AND THEN MOVE EWD.
THAT WOULD BRING THE GREATEST RISK ACRS THE AREA DURING THE EVENING
HOURS.

NOT SURE WHAT THE COVERAGE OF THE STORMS WOULD BE LIKE...SO BACKED THE
POPS ACRS THE SE PART OF THE FCST AREA DOWN TO CHC CATEGORY. STUCK WITH
LIKELY POPS ACRS THE REST OF THE AREA.

SINCE THE FRONT WL BE SLOWER TO EXIT THE AREA FRI...ADDED CHC POPS ACRS
THE SE 1/2 OF THE AREA. WARM START TO THE DAY COULD ALLOW TEMPS TO WARM
ABV GUID...BUT THINK THERE WL BE QUITE A FEW CLOUDS ARND WITH THE
BAROCLINIC ZONE ACRS THE AREA...SO STUCK CLOSE TO PREV FCST.

.LONG TERM...FRI NGT THRU NEXT THU. MAIN FCST CHALLENGE WL BE ON TEMPS
AS NE WI TO GO MAINLY INTO A DRY PATN STARTING FROM SAT ONWARD.

CDFNT EXPECTED TO BE DEPARTING THE SE CORNER OF THE FCST AREA FRI
EVENING (CLOSER TO ETA/NGM TIMING). PREFER TO LEAVE EVENING CHC POP
WORDING ACROSS CNTRL/E-CNTRL WI DUE TO THE FACT THAT THIS FNT MAY BE
SLOW TO CLR AND WE ARE STILL IN FAVORABLE RIGHT ENTRANCE RGN OF THE UPR
JET. WL USE THE MET GUID FOR MIN TEMPS WHICH IS A COMPROMISE SOLN. A
MUCH COOLER AND DRIER DAY ON TAP FOR SAT AS CANADIAN HI PRES BUILDS INTO
THE RGN. 8H TEMPS ONLY AROUND +6C...THUS EXPECT A GOOD DEAL OF DIURNAL
CU TO DVLP. THIS SHOULD TRANSLATE TO KEEPING TEMPS ONLY IN THE 60S. WEAK
HI PRES SITUATED OVR NE WI SAT NGT LEADING TO DIMINISHING WNDS. A COOL
NGT IN STORE WITH TEMPS DEPENDENT ON HOW MUCH CLD CVR REMAINS. PLAN ON
LOWERING EXPECTED MIN TEMPS A GOOD 5 DEGS BASED ON SOME BREAKS IN THE
CLDS. HI PRES THEN SHIFTS EWD ON SUNDAY ALLOWING RETURN FLOW TO
GRADUALLY DVLP. WL BE WATCHING A FNTL BNDRY DROP INTO THE UPR MIDWEST
SUNDAY AFTERNOON BUT NO AFFECT ON OUR WEATHER DURING THE DAY. TEMPS
SHOULD BE ABLE TO WARM A FEW DEGS BUT STILL BE BLO NORMAL.

HEADED INTO THE EXTENDED...ZNL FLOW AT THE START OF NXT WEEK TO AMPLIFY
AS STG UPR TROF DIGS INTO THE WEST COAST. MEAN FLOW TO THEN BE MORE SW
ACROSS MOST OF THE COUNTRY WITH THE JET REMAINING TO OUR NORTH AND WEST.
THIS PATN SHOULD KEEP THE MAJORITY OF WEATHER MAKERS ACROSS THE PLAINS
NEWD INTO CANADA LEAVING A RELATIVELY DRY WEEK AHD. TEMPS EXPECTED TO BE
AT OR ABV NORMAL.

IF THERE IS AN EXCEPTION TO THE DRY EXTENDED...IT WOULD BE SUN NGT INTO
MON AS A FNTL BNDRY ATTEMPTS TO DROP SOUTH THRU THE STATE. BETTER
DYNAMICS REMAIN TO OUR NORTH AND NOT MUCH MSTR FOR THE BNDRY TO USE.
NEVERTHELESS...WL INCLUDE A SLGT CHC POP FOR NRN WI. WL LEAVE THE REST
OF THE FCST AREA DRY WITH HI PRES IN PLACE TO OUR SOUTH. THE BNDRY
PROGGED TO WEAKEN/DISSIPATE MON NGT LEAVING HI PRES IN CONTROL FOR TUE.
AS THE UPR TROF HITS THE WEST COAST NXT WED ALLOWING HGTS TO BUILD OVR
THE ERN U.S.  NOT SURE WHERE GFS GETS ITS MINOR QPF AS ATM TO BECOME
INCREASINGLY CAPPED. WL LEAVE FCST DRY WITH TEMPS RISING ABV NORMAL. NE
WI FIRMLY LOCKED IN SW FLOW BY NXT THU. CONTINUED PUSH OF WARM AIR
SHOULD KEEP ATM CAPPED WITH NO FOCUS FOR ANY PCPN. TEMPS TO BE ABV
NORMAL WITH 80S PSBL OVR CNTRL WI.

.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

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

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREEN BAY WI
330 PM CDT THU AUG 26 2004

WIZ005-010>013-018>022-030-031-035>040-045-048>050-073-074-271100-
VILAS-ONEIDA-FOREST-FLORENCE-NORTHERN MARINETTE-SOUTHERN MARINETTE-
LINCOLN-LANGLADE-MENOMINEE-NORTHERN OCONTO-SOUTHERN OCONTO-DOOR-
MARATHON-SHAWANO-WOOD-PORTAGE-WAUPACA-OUTAGAMIE-BROWN-KEWAUNEE-WAUSHARA-
WINNEBAGO-CALUMET-MANITOWOC-
330 PM CDT THU AUG 26 2004

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

.DAY ONE...TONIGHT AND FRIDAY

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE AREA
TONIGHT. THE RISK IS OF LARGE HAIL AND DAMAGING WINDS. IT WILL
BEGIN IN NORTH-CENTRAL WISCONSIN DURING THE EARLY EVENING HOURS...
AND THEN SPREAD EAST AND SOUTHEAST AND REACH THE LAKESHORE BY LATE
EVENING.

SEVERE STORMS ARE EXPECTED TO DEVELOP OVER MINNESOTA AND IOWA DURING THE
LATE AFTERNOON AS A COLD FRONT AND STRONG UPPER LEVEL JET STREAM NEAR
THE REGION. THE STORMS ARE EXPECTED TRACK EAST ACROSS THE AREA TONIGHT.

.DAYS TWO THROUGH SEVEN...FRIDAY NIGHT THROUGH NEXT THURSDAY

THE PROBABILITY OF WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS EVENING.

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