Thunderstorms that formed ahead of a cold front pushed through much of Wisconsin during the early hours of August 3rd. One of the storms produced a microburst that caused tree damage on Rib Mountain.
Every event with a place to put it. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS GRB wrote it up.
Thunderstorms that formed ahead of a cold front pushed through much of Wisconsin during the early hours of August 3rd. One of the storms produced a microburst that caused tree damage on Rib Mountain.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Green Bay, WI wrote its last area forecast discussion before the first event at Aug 2, 7:22 PM CST, 4 hours 46 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREEN BAY WI 822 PM CDT SUN AUG 2 2009 .UPDATE...WILL UPDATE ZONES TO INCREASE TO LIKELY POPS ACROSS THE ENTIRE AREA TONIGHT. AT 01Z PRECIPITATION WAS MOVING ACROSS WISCONSIN AHEAD OF A MID LEVEL SHORT WAVE. THE NEAREST LIGHTNING SHOWING UP ON THE LIGHTNING DETECTION CHART WAS IN WESTERN MINNESOTA. BUT MODELS HAD A STRONG SOUTHWEST 850MB JET DEVELOPING OVER WISCONSIN THIS EVENING...VEERING OVERNIGHT. LAPSE RATES IN THE FORECAST AREA WERE RATHER STEEP DURING THE LATE AFTERNOON...BUT EXPECT EVENING RAINFALL TO MODIFY THE AIRMASS OVER THE NORTHWOODS. HPC EXPANDED SLIGHT RISK AREA TO INCLUDE ABOUT THE SOUTHWEST HALF OF THE CWA. MG && .PREV DISCUSSION...ISSUED AT 248 PM CDT SUN AUG 2 2009... SYNOPSIS...UPR PATTERN WITH STG RIDGE ALONG THE WEST COAST AND FAIRLY DEEP TROF OVER THE GREAT LAKES RGN WL PERSIST FOR THE FIRST PART OF THE FCST PERIOD. BUT IT/S LOOKING INCREASINGLY LIKELY THAT SIG CHGS WL OCCUR LATER IN THE FCST PERIOD. CONSENSUS OF THE MODELS IS THAT REMNANTS OF THE UPR TROF CURRENTLY UDERCUTTING THE WRN RIDGE WL SLOWLY WORK EWD...AND RESULT IN UPR RIDGE POSN REFORMING OVER THE SERN STATES BY LATE IN THE UPCOMING WEEKEND. THAT WOULD LEAD TO A WARMER...AND POTENTIALLY MUCH WETTER PATTERN DEVELOPING ACRS THE FCST AREA BY THE UPCOMING WEEKEND. UNTIL THEN...EXPECT MORE AOB NORMAL TEMPS...WITH SCT LGT-MODERATE PCPN AMNTS AS SHRTWVS MV THROUGH CURRENT LNGWV TROF POSN NR THE AREA. SHORT TERM...TNGT/MON. DRY AIR HOLDING OFF PCPN PRETTY WELL THIS AFTN. LEADING EDGE OF PCPN STUCK OUT NR THE MN BORDER...WITH LEADING ELEMENTS EVAPORATING AS THEY MV E. SFC DWPTS INCRG ACRS MN...AND THAT COMBINED WITH CONTD ISENT LIFT SHOULD EVENTUALLY LEAD TO PCPN DEVELOPING SEWD ACRS THE FCST AREA. STRONGEST LIFT WL BE OVER THE N...SO TOOK POPS UP TO LIKELY THERE. STUCK WITH CHC ELSEWHERE. RAISED MINS A BIT AS THERE WL BE SOME CLDS...INCRG MOISTURE...AND SOME WIND ACRS THE AREA TGNT. MAIN BAND OF PCPN...PROBABLY JUST IN THE FORM OF SHRA BY LATE TNGT...SHOULD EXIT THE E EARLY MON. STRUGGLED TO FIGURE OUT WHETHER TO KEEP CHC IN THE FCST FOR POSSIBLE REDEVELOPMENT DURING THE AFTN. ON ONE HAND...THERE SHOULD BE LINGERING SHALLOW MOISTURE AND SOME LOW-LEVEL CONVERGENCE NEAR SFC TROF PROGGED TO BE ACRS THE AREA. ON THE OTHER HAND...DEEPER MOISTURE WL GET STRIPPED OFF TO THE EAST...AND 850 MB FLOW GOING WLY WITH WEAK CAA DEVELOPING NORMALLY VERY UNFAVORABLE FOR GETTING CONVECTION TO FIRE. DECIDED TO KEEP CHC IN THE E FOR THE AFTN...THOUGH WOULD THINK COVERAGE WOULD BE QUITE LIMITED AND POSSIBLY TIED TO ANY AREAS OF SMALLER SCALE CONVERGENCE AS ADDITIONAL LIFT MAY BE NEEDED TO BREAK A WK CAP. MET TEMPS LOOKED TOO WARM...SO WENT WITH BLEND OF SREF AND GFS-BASED STATISTICAL GUID NUMBERS. LONG TERM...MON NGT THRU NXT SUNDAY. MDLS ARE GETTING BETTER IN SYNC WITH THE PROJECTED OVERALL CHG IN THE MEAN FLOW ACROSS THE CONUS LTR THIS WEEK. THE PERSISTENT WRN CONUS UPR RDG/NE CONUS UPR TROF PATN OF THE PAST MONTH WL TRANSITION TO A WRN CONUS UPR TROF/ SE CONUS UPR RDG. FOR NE WI...THIS SIGNIFICANT CHG SHOULD BRING WARMER...MORE MOIST AIR BACK TO THE RGN. PCPN CHCS MAY EVENTUALLY BE LINKED TO PSBL MCS DEVELOPMENT TO OUR WEST LTR IN THE WEEK. MDLS INDICATE A SECONDARY CDFNT WL DROP THRU WI MON NGT. THIS RAISES THE QSTN FOR ADDL PCPN ESP WITH A TRAILING SHRTWV HEADED TOWARD LK SUPERIOR. THE PBLM FOR ADDING PCPN TO THE FCST IS THAT A GOOD DEAL OF THE MSTR WL HAVE BEEN SCOURED OUT BY THE FIRST CDFNT AND THE BETTER FORCING ASSOCIATED WITH THE ADVANCING SHRTWV SHOULD STAY TO OUR NORTH. AFTER COLLABORATION WITH DLH AND MQT...HAVE DECIDED THAT THERE IS ENUF FORCING/LIFT EVIDENT TO ADD A MINIMAL POP TO NRN WI. ENUF CLD CVR AROUND THRU THE NGT TO HELP HOLD TEMPS UP AND WITH THICKER CLDS NORTH...HAVE ADDED A FEW DEGS THERE. CDFNT DEPARTS SE AND SHRTWV SHIFTS EAST BY TUE...THEREBY ALLOWING HI PRES TO START BUILDING EAST TOWARD THE WRN GREAT LKS. THE AIRMASS WL TEND TO DRY OUT DURING THE DAY AND HARD TO FIND ANY OTHER FOCUS FOR PCPN SO HAVE REMOVED THE MENTION OF SHWRS FROM THE FCST. EXPECT TEMPS TO COOL A LITTLE BEHIND THE FROPAS...AND PREV SHIFTS FCST STILL LOOKS GOOD FOR THE MOST PART. THE HI PRES CONTS TO BUILD TOWARD WI TUE NGT...THUS QUIET CONDITIONS TO PREVAIL. LOOK FOR SKIES TO BECOME MOSTLY CLR OVRNGT AND COMBINED WITH RELATIVELY LGT WNDS...TEMPS WL BE ABLE TO DROP OFF AT A PRETTY GOOD CLIP. HAVE KNOCKED OFF SEVERAL DEGS FROM MIN TEMPS WITH MID 40S NORTH TO MID 50S NEAR LK MI. THE WEAK HI PRES TO STRETCH FROM THE CANADIAN PRAIRIE SE INTO THE GREAT LKS ON WED SO DO NOT SEE ANY CHC OF PCPN FOR NE WI. MEAN FLOW IS STILL NW ON WED...THUS TEMPS WL BE ABT 5 DEGS BLO NORMAL DESPITE A FAIR AMT OF SUNSHINE. INITIALLY...WAS WORRIED ABT A SHRTWV DROPPING SEWD INTO THE WRN GREAT LKS ACCOMPANIED BY A 120 KT JET STREAK WED NGT. HOWEVER... MDLS HAVE TRENDED NORTH WITH BOTH FEATURES...THUS LEAVING LITTLE IF ANY FORCING OR LIFT TO PLAY WITH. IN THE END...HAVE GONE DRY FOR BOTH WED NGT AND THU. THE SIGNIFICANT PATN CHG BEGINS BY THU NGT AS A POTENT SHRTWV TROF HITS THE PAC NW AND THE UPR RDG GETS SHOVED EAST THRU THE ROCKIES TOWARD THE PLAINS BY FRI. SFC HI TO REMAIN IN CONTROL OVR THE GREAT LKS AND SEE NO OTHER FORCING MECHANISM TO GENERATE ANY PCPN. THUS...HAVE REMOVED THE SHWRS/TSTMS FROM FRIS FCST. TEMPS STILL A TOUCH BELOW NORMAL... BUT GETTING CLOSER TO TYPICAL EARLY AUGUST VALUES. FCST BECOMES MORE MUDDLED BY NXT WEEKEND AS THE UPR RDG EVENTUALLY REACHES THE GREAT LKS...BUT POSSIBILITY EXISTS FOR SOME SORT OF MCS TO DVLP EITHER FRI NGT OR SAT NGT. EARLY INDICATIONS ARE THAT A MCS WL DVLP OVR THE MIDWEST FRI NGT AND FOLLOW THE THICKNESS VALUES SEWD THRU IA/NRN AND CNTRL IL. THEREFORE...HAVE REMOVED THE PCPN CHCS FOR NE WI FRI NGT. BY SAT...A WRMFNT IS FCST TO START LIFTING NORTH AND BE APPROACHING WI LTR IN THE DAY. THIS FNT COULD KICK OFF SOME TSTM ACTIVITY AS INSTABILITY INCREASES AND MSTR SURGES NWD. A SHRTWV TROF RIDING NEWD ON THE BACKSIDE OF THE UPR RDG WL SEND A CDFNT ACROSS WI ON SUNDAY...THUS A CONTINUED THREAT OF STORMS. TEMPS WL TAKE A NOTICEABLE UPSWING WITH READINGS REACHING WELL INTO THE 80S BY SUNDAY. AVIATION...EXPECT FAIRLY HIGH CIGS...EVEN IN SHRA/TSRA THAT DEVELOP TNGT. STATISTICAL GUID SUGGESTED LOWER CIGS POSSIBLE FOR A SHORT TIME TOMORROW MORNING. THAT WOULD SEEM TO DEPEND ON HOW MUCH RAIN WE GET. NOT MUCH IN THE WAY OF LOWER CIGS BEHIND SYSTEM ATTM...AND AS DRY AS IT/S BEEN DECIDED TO FOREGO BRINGING IN PERIOD OF MVFR OR EVEN IFR CIGS RIGHT BEHIND THE FRONT. NEXT SHIFT CAN REASSESS. CERTAINLY SOME RISK OF THUNDER LATER THIS EVENING AND OVERNIGHT. BUT AT THIS POINT...RISK DEEMED TOO LOW FOR EXPLICIT INCLUSION IN TAFS. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. &&
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE GREEN BAY WI 904 PM CDT SUN AUG 2 2009 WIZ005-010>013-018>022-030-031-035>040-045-048>050-073-074-040215- VILAS-ONEIDA-FOREST-FLORENCE-NORTHERN MARINETTE-LINCOLN-LANGLADE- MENOMINEE-NORTHERN OCONTO-DOOR-MARATHON-SHAWANO-WOOD-PORTAGE- WAUPACA-OUTAGAMIE-BROWN-KEWAUNEE-WAUSHARA-WINNEBAGO-CALUMET- MANITOWOC-SOUTHERN MARINETTE-SOUTHERN OCONTO- 904 PM CDT SUN AUG 2 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL AND NORTHEAST WISCONSIN. .DAY ONE...TONIGHT THUNDERSTORMS ARE LIKELY OVERNIGHT...ALONG AND SOUTHWEST OF A LINE FROM TOMAHAWK TO MANITOWOC. SOME OF THE STORMS MAY BE SEVERE...WITH DAMAGING WINDS AND LARGE HAIL. THERE IS ALSO CHANCE OF THUNDERSTORMS ACROSS THE REST OF NORTHEAST WISCONSIN. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SUNDAY THERE IS A CHANCE OF THUNDERSTORMS MAINLY OVER EASTERN WISCONSIN MONDAY AFTERNOON. THE STORMS ARE NOT EXPECTED TO BE SEVERE. THE NEXT CHANCE OF MORE WIDESPREAD THUNDERSTORMS WILL BE DURING THE UPCOMING WEEKEND. IT IS TOO EARLY TO DETERMINE THE RISK OF SEVERE WEATHER WITH THOSE STORMS. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED TONIGHT. LMZ521-522-541>543-040215- THE BAY OF GREEN BAY SOUTH OF A LINE FROM CEDAR RIVER MI TO ROCK ISLAND PASSAGE-LAKE MICHIGAN FROM WASHINGTON ISLAND TO SHEBOYGAN- 904 PM CDT SUN AUG 2 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHWEST LAKE MICHIGAN AND THE WATERS OF GREEN BAY. .DAY ONE...TONIGHT CONDITIONS HAZARDOUS TO SMALL CRAFT WILL DEVELOP ON THE LAKE BY LATE TONIGHT. THERE IS A CHANCE OF THUNDERSTORMS TONIGHT. THE STORMS ARE NOT EXPECTED TO BE SEVERE...BUT COULD CONTAIN GUSTY WINDS AND BRIEF HEAVY RAIN. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SUNDAY CONDITIONS HAZARDOUS TO SMALL CRAFT WILL CONTINUE ON THE LAKE ON MONDAY. THERE IS A CHANCE OF THUNDERSTORMS MONDAY AFTERNOON. THE STORMS ARE NOT EXPECTED TO BE SEVERE. THE NEXT CHANCE OF MORE WIDESPREAD THUNDERSTORMS WILL BE DURING THE UPCOMING WEEKEND. IT IS TOO EARLY TO DETERMINE THE RISK OF SEVERE WEATHER WITH THOSE STORMS.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE GREEN BAY WI 928 PM CDT SUN AUG 2 2009 WIZ030-030315- MARATHON- 928 PM CDT SUN AUG 2 2009 ...STRONG THUNDERSTORM ACROSS NORTHWESTERN MARATHON COUNTY... AT 925 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM NEAR DORCHESTER...OR 8 MILES SOUTHEAST OF MEDFORD...MOVING EAST AT 35 MPH. BRIEF HEAVY RAIN...SMALL HAIL...AND WINDS TO 40 MPH ARE EXPECTED WITH THIS STORM. THIS STORM WILL AFFECT MAINLY RURAL AREAS OF NORTHWESTERN MARATHON COUNTY...INCLUDING THE TOWNS OF MILAN...ATHENS...PONIATOWSKI...RIB FALLS...LITTLE CHICAGO AND MARATHON CITY. ECKBERG
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE GREEN BAY WI 1008 PM CDT SUN AUG 2 2009 WIZ030-030345- MARATHON- 1008 PM CDT SUN AUG 2 2009 ...CLUSTERS OF THUNDERSTORMS MOVING INTO EASTERN MARATHON COUNTY... AT 1009 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A CLUSTER OF THUNDERSTORMS ALONG A LINE EXTENDING FROM 6 MILES SOUTHWEST OF MERRILL TO WAUSAU TO 15 MILES WEST OF MOSINEE...MOVING EAST AT 35 MPH. THESE STORMS ARE CAPABLE OF PRODUCING WIND GUSTS TO 40 MPH. THE STRONGER STORMS WILL ALSO PRODUCE LOCALLY HEAVY RAIN WITH RAINFALL RATES OF 1 TO 2 INCHES PER HOUR. SOME PONDING OF WATER CAN BE EXPECTED ON AREA ROADS WITH THE HEAVIER STORMS. THESE STORMS WILL BE NEAR... RIB MOUNTAIN BY 1010 PM CDT. WESTON BY 1020 PM CDT. MOSINEE BY 1025 PM CDT. BEVENT BY 1045 PM CDT. THE TOWNS OF MARATHON CITY...EDGAR...RIB FALLS...BROKAW...RIB MOUNTAIN STATE PARK...SCHOFIELD...NUTTERVILLE...SUNSET...ROTHSCHILD AND EVERGREEN ARE ALSO IN THE PATH OF THESE STORMS. ECKBERG
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE GREEN BAY WI 1246 AM CDT MON AUG 3 2009 WIZ018-030-030630- LINCOLN-MARATHON- 1246 AM CDT MON AUG 3 2009 ...STRONG THUNDERSTORMS MOVING ACROSS MARATHON AND SOUTHWESTERN LINCOLN COUNTIES... AT 1246 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING STRONG THUNDERSTORMS ALONG A LINE EXTENDING FROM 6 MILES WEST OF MERRILL TO ABBOTSFORD...MOVING SOUTHEAST AT 40 MPH. THESE STORMS WILL BE CAPABLE OF PRODUCING TORRENTIAL RAINS...WIND GUSTS UP TO 45 MPH AND HAIL UP TO A HALF INCH IN DIAMETER. THESE STORMS WILL BE NEAR... SPENCER AND STRATFORD AROUND 100 AM CDT. MARATHON CITY AROUND 105 AM CDT. WAUSAU AND RIB MOUNTAIN AROUND 115 AM CDT. WESTON AROUND 120 AM CDT. MOSINEE AROUND AROUND 125 AM CDT. BEVENT AROUND 135 AM CDT. THE TOWNS OF COLBY...ATHENS...MILAN...HAMBURG...PONIATOWSKI... LITTLE CHICAGO...ROZELLVILLE...FENWOOD AND EDGAR ARE ALSO IN THE PATH OF THESE STORMS. ECKBERG
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE GREEN BAY WI 101 AM CDT MON AUG 3 2009 WIZ035-036-030645- PORTAGE-WOOD- 101 AM CDT MON AUG 3 2009 ...STRONG THUNDERSTORMS EXPECTED IN PORTAGE AND WOOD COUNTIES... AT 1259 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING TWO CLUSTERS OF STRONG THUNDERSTORMS. THE FIRST LINE OF STRONG THUNDERSTORMS EXTENDED FROM 9 MILES SOUTHEAST OF MERRILL TO 7 MILES SOUTHWEST OF SPENCER...MOVING SOUTHEAST AT 40 MPH. ANOTHER CLUSTER OF THUNDERSTORMS WAS ACROSS CLARK AND JACKSON COUNTIES. THIS CLUSTER OF THUNDERSTORMS WAS MOVING TO THE EAST AT 45 MPH. THIS CLUSTER OF THUNDERSTORMS WILL PRODUCE WIND GUSTS UP TO 50 MPH...TORRENTIAL RAINS AND HAIL. THESE STORMS WILL BE NEAR... MARSHFIELD AROUND 110 AM CDT. PITTSVILLE BY 125 AM CDT. BABCOCK BY 135 AM CDT. WISCONSIN RAPIDS BY 140 AM CDT. STEVENS POINT AND WHITING BY 145 AM CDT. THE TOWNS OF BAKERVILLE...LINDSEY...HEWITT...AUBURNDALE...BETHEL... ARPIN...BLENKER...SHERRY...MILLADORE AND DEXTERVILLE ARE ALSO IN THE PATH OF THESE STORMS. ECKBERG
The Green Bay radar (KGRB), 129 km away, was scanning. The volume nearest the first event began at 06:09 UTC.
1 thunderstorm wind. Local standard time, as filed.
Thunderstorms snapped or uprooted two dozen trees on Rib Mountain, some as wide as 2 feet in diameter. The fallen trees caused damage to 6 homes in the area.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wisconsin in 2009Every state in 2009This day in weather historyWarnings in Wisconsin, August 2009
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 193170.