A shower associated with an upper low pressure system and moist atmosphere produced a weak tornado about a mile east-southeast of Wautoma. Only minimal tree damage occurred.
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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.
A shower associated with an upper low pressure system and moist atmosphere produced a weak tornado about a mile east-southeast of Wautoma. Only minimal tree damage occurred.
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 Jul 20, 11:22 AM CST, 33 minutes earlier.
Area Forecast Discussion National Weather Service Green Bay WI 1222 PM CDT Fri Jul 20 2018 Updated aviation portion for 18Z TAF issuance .SHORT TERM...Today...Tonight...and Saturday Issued at 305 AM CDT Fri Jul 20 2018 A surface low, analyzed near Prairie du Chien at 07Z, will continue moving east through southern Wisconsin today and this evening, then slowly drift towards northern Indiana by Saturday. Although Doppler Radar is currently not showing much in the way of showers across the western Great Lakes, that is expected to change later today as daytime heating increases instability with renewed activity across the region. The instability will also mean isolated to scattered thunderstorms will accompany the showers at times, with the best chances across the south closer to the upper level low and where the best instability will be. Despite the instability and chances for thunderstorms, severe weather is not expected as MUCAPEs will be below 1000 J/kg with a fairly weak bulk shear values. Some heavy rain is possible at times with the most vigorous activity, however significant flooding is not expected as area rivers are running well below action stage. Although the main surface low will track east on Saturday, the area will still be under the mid level trough as several PV anomalies track through the western Great Lakes region. MUCAPEs on Saturday will actually be a bit better than today, with values of 700 to 1200 J/kg, however bulk shear will still be very weak with values around 10 knots. Therefore while additional showers and thunderstorms are expected on Saturday, severe storms are not expected. Abundant cloud cover and precipitation will keep highs below normal today in the lower to middle 70s. Lows tonight will generally range from the middle to upper 50s across the north, with lower to middle 60s across the south under continued cloud cover. Similar conditions on Saturday will lead to similar temperatures as today, however some upper 70s will be possible across central Wisconsin with the area further removed from the upper low. .LONG TERM...Saturday Night Through Thursday Issued at 305 AM CDT Fri Jul 20 2018 Forecast concerns mainly revolve around precip chances late in the weekend with the departing upper low, and also midweek associated with a cold front. The ecmwf and gfs compare relatively well, so used a blend of these two models for this part of the forecast. Saturday night through Sunday night...Even though low pressure will gradually be moving south from southern Lake Michigan to the Ohio Valley on Saturday night, deep cyclonic flow will remain in place over northeast WI without much of an influx of drier air. As a result, progged soundings remain relatively saturated through the column and therefore expect periods of showers to continue through the evening, though coverage should diminish some during the overnight. Drier air finally makes inroads into northeast WI on Sunday afternoon. But until then, think there will be ample cloud cover with spotty showers on Sunday. Models show the clearing trend continues into Sunday night. But with any clearing and light winds, looks like a decent setup for fog late. Highs on Sunday should approach seasonable norms. Rest of the forecast...Models insist on pushing a decaying cold front across the area on Monday night or Tuesday. Convergence along the front looks meager by the time the front arrives, so precip chances will remain pretty low, and mainly northwest of the Fox Valley. A more potent front remains on track to impact the area on Wednesday into Wednesday night. Will have some instability ahead of the front, so scattered storms look possible. As upper troughing builds in behind the front, turning cooler and showery late in the week. && .AVIATION...for 18Z TAF Issuance Issued at 1220 AM CDT Fri Jul 20 2018 A large area of low pressure will slowly move from south-central Wisconsin this afternoon to over southern Lake Michigan by tonight and into northern Indiana Saturday morning. Scattered to numerous showers will be accompanied by isolated to scattered thunderstorms through the evening hours as this low pressure moves south of our region. The best chance for thunderstorms will be across the south closer to the low this afternoon when instability is at its greatest. These storms should not become strong, but their downpours could bring down visibility to IFR. Expect widespread MVFR ceilings this afternoon and early evening with pockets of VFR. Showers will diminish tonight, and drier air will filter in from the north. MVFR and VFR ceilings are likely overnight, but some IFR late tonight and early Saturday. Gusty north-northeast winds will develop by Saturday afternoon with more showers. .KOSH...MVFR ceilings, with pockets of VFR, will continue through this evening. Expect scattered to numerous showers and isolated to scattered thunderstorms this afternoon. The easterly winds will back and become northeasterly by late this afternoon. IFR conditions are likely late tonight and early Saturday, before returning to MVFR later Saturday morning. Gusty north-northeast winds will develop, along with showers, by Saturday afternoon. && .GRB WATCHES/WARNINGS/ADVISORIES... Beach Hazards Statement through late tonight for WIZ022-040-050. && SHORT TERM.....Kurimski LONG TERM......MPC AVIATION.......Grochocinski/Kallas
Hazardous Weather Outlook National Weather Service Green Bay WI 335 AM CDT Fri Jul 20 2018 WIZ005-010>013-018>022-030-031-035>040-045-048>050-073-074-210845- Vilas-Oneida-Forest-Florence-Northern Marinette County-Lincoln- Langlade-Menominee-Northern Oconto County-Door-Marathon-Shawano- Wood-Portage-Waupaca-Outagamie-Brown-Kewaunee-Waushara-Winnebago- Calumet-Manitowoc-Southern Marinette County- Southern Oconto County- 335 AM CDT Fri Jul 20 2018 This Hazardous Weather Outlook is for north-central and northeast Wisconsin. .DAY ONE...Today and Tonight There is a chance of thunderstorms across the area today. A few thunderstorms may also linger over central and northeast Wisconsin tonight. The storms are not expected to be severe, but they could produce locally heavy rainfall. Gusty east winds will result in an increased risk of dangerous currents and hazardous swimming conditions at Lake Michigan beaches through tonight. .DAYS TWO THROUGH SEVEN...Saturday through Thursday The chance of thunderstorms will continue on Saturday. Severe storms are not anticipated. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed today or tonight. LMZ521-522-541>543-210845- The Bay of Green Bay south of a line from Cedar River MI to Rock Island Passage-Lake Michigan from Washington Island to Sheboygan- 335 AM CDT Fri Jul 20 2018 This Hazardous Weather Outlook is for portions of northwest Lake Michigan and the waters of Green Bay. .DAY ONE...Today and Tonight Increasing southeast winds and building waves will result in hazardous conditions for small craft on Lake Michigan through early this evening. Isolated thunderstorms may also pose a hazard to mariners. .DAYS TWO THROUGH SEVEN...Saturday through Thursday Conditions hazardous to small craft will again be possible on Saturday afternoon through Saturday night due to gusty northeast winds and large waves. Kurimski/MPC
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREEN BAY WI
1200 PM CDT FRI JUL 20 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1159 AM HEAVY RAIN PLOVER 44.45N 89.53W
07/20/2018 M1.22 INCH PORTAGE WI CO-OP OBSERVER
RAINFALL SINCE MIDNIGHT
&&The Green Bay radar (KGRB), 103 km away, was scanning. The volume nearest the first event began at 17:54 UTC.
1 tornado. Local standard time, as filed.
A weak tornado briefly touched down near Highway 21 about one mile east-southeast of Wautoma. Several eyewitnesses observed the tornado on the ground for 10 to 15 seconds. A few white pine trees had branches broken (DI 28, DOD 1).
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wisconsin in 2018Every state in 2018This day in weather historyThe tornado archive for Wisconsin, 2018Warnings in Wisconsin, July 2018
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: 758170.