A mesoscale convective system tracked across central Wisconsin during the morning hours, producing isolated wind damage.
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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 mesoscale convective system tracked across central Wisconsin during the morning hours, producing isolated wind damage.
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 10, 5:17 AM CST, 2 hours 3 minutes earlier.
Area Forecast Discussion National Weather Service Green Bay WI 617 AM CDT Mon Aug 10 2020 Updated aviation portion for 12Z TAF issuance .SHORT TERM...Today...Tonight...and Tuesday Issued at 359 AM CDT Mon Aug 10 2020 MSAS analysis/surface observations show the cold front stretching from the Arrowhead of MN south-southwest to north-central IA around 09Z. Satellite imagery shows a cluster of storms developing along the cold front over northwest WI/eastern MN this morning. Additionally, low clouds have developed across much of central WI into northeast WI with bases around 600ft. Radar trends continue to show the aforementioned cluster of thunderstorms developing and shifting eastward at or around 35 mph early this morning. A few of the storms have produced marginally severe hail across east- central MN this morning. Today: The cold front will continue to shift southeastward through the area through the day, moving from central WI around 12Z this morning to the Fox Valley/Door Peninsula by or around 18Z. Along and ahead of the cold front, enough forcing and moisture will be in place to give at least a broken line of showers and thunderstorms. This is probably the best feature, to line the precip chances along, that has been seen over the past couple of days. MUCAPE is progged to be around 1500-2500 J/kg ahead of the front, which will again be plenty to see thunderstorm potential. The elevated instability is expected to increase across the Fox Valley into far northeast Wisconsin by 18Z as the front passes through the area. These values may be overdone to some extent as much of the area will likely remain under increased cloud cover through much of the day. Shear values over these locations are also expected to increase to around 25kts, which will lead to a risk of isolated strong to possibly severe thunderstorms by late morning and early afternoon. Heavy rain, hail and gusty winds would be the most likely threats (in that order), with the fairly steep mid-level lapse rates (7-8 C/km) and some dry air in the mid levels. Areas to the west and northwest of the front will see a bit cooler and drier day, with more comfortable humidity levels and some sunshine during the afternoon hours. High temperatures are forecast to be in upper 70s and low 80s ahead of the front and mid to upper 70s behind the front. Tonight: Much quieter weather expected. Dry high pressure will build in behind the front, allowing skies to clear across all of the CWA during the evening. Winds are expected to become light out of the west overnight and PWATs are are progged to be about 50% of normal, which should allow temperatures too quickly cool into the 50s across much of the area. It wouldn't be completely out of the question to see some upper 40s in the typical cold spots. The increased soil moisture, light winds and cool temperatures may also result in some patchy ground fog development overnight. Tuesday: The aforementioned surface ridge is expected to remain in place through this time period, allowing for mostly clear skies and more comfortable humidity values across the area. Deeper mixing during the afternoon, will likely allow lower dewpoints to mix down across the area; therefore, dropped them down a few degrees, especially across the sandy soil locations. High temperatures are forecast to be in the upper 70s to low 80s, coolest along the lakeshore. .LONG TERM...Tuesday Night Through Sunday Issued at 359 AM CDT Mon Aug 10 2020 Fairly zonal flow noted at 500mb into next weekend as temperatures expected to remain above normal during the period. The new ECMWF indicated a possible shift in the pattern late next weekend into the following work week as 500mb ridge builds across the western United States and trough deepens across the Great Lakes region. For Tuesday night and Wednesday, dry conditions are expected with fairly seasonal humidity readings for August. Like the last few nights, significant differences in when the chances of rain return to the forecast area. Canadian model has something moving into the area Wednesday evening while the GFS has something across the north for the same time frame. Meanwhile, the NAM/ECMWF keep Wednesday night dry. In matter of fact, the ECMWF would keep things dry through at least Friday, if not into early next weekend. Have low chance pops from time to time Thursday into Saturday, but confidence is low if any rain would occur. Prefer the ECMWF solution for now. No changes made to the Sunday period for now due to low confidence in the evolution of the pattern. Temperatures should remain above normal through the weekend. && .AVIATION...for 12Z TAF Issuance Issued at 617 AM CDT Mon Aug 10 2020 Main forecast concerns with the TAF issuance is the low clouds at the TAF sites this morning and the potential for showers and thunderstorms through this afternoon. The cold front over western WI has touched off a broken line of showers and thunderstorms this morning, which will likely impact RHI/CWA/AUW during the first few hours of the TAF issuance. The cold front is expected to reach GRB/ATW/MTW between 17Z and 21Z, which will be the most likely time for showers and storms to impact those sites. A couple of the storms could become strong and produce gusty winds and hail late this morning into this afternoon. After the front exits the region by 00Z, improving conditions can be expected at each TAF site for tonight into Tuesday. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && SHORT TERM.....Cooley LONG TERM......Eckberg AVIATION.......Cooley
Hazardous Weather Outlook National Weather Service Green Bay WI 451 AM CDT Mon Aug 10 2020 WIZ005-010>013-018>022-030-031-035>040-045-048>050-073-074-111000- 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- 451 AM CDT Mon Aug 10 2020 This Hazardous Weather Outlook is for north-central and northeast Wisconsin. .DAY ONE...Today and Tonight Thunderstorms may redevelop through early this afternoon, especially in east-central Wisconsin. A few of the storms could be strong or severe and produce large hail, gusty winds and heavy rainfall. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday There is a chance of thunderstorms will return late in the work week and continue into next weekend. It is too early to determine if any of the storms will become severe. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed this afternoon across northeast Wisconsin. Spotters are requested to report any wind damage, large hail, flooding or rainfall over an inch to the National Weather Service in Green Bay. LMZ521-522-541>543-111000- The Bay of Green Bay south of a line from Cedar River MI to Rock Island Passage-Lake Michigan from Washington Island to Sheboygan- 451 AM CDT Mon Aug 10 2020 This Hazardous Weather Outlook is for portions of northwest Lake Michigan and the waters of Green Bay. .DAY ONE...Today and Tonight Areas of dense fog have developed this morning and will likely linger into the early afternoon hours in the nearshore waters of Lake Michigan. A dense fog advisory has been issued. Thunderstorms may pose a hazard to boaters on the bay and lake today into early this evening. Some of the storms could produce strong winds and large hail. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Thunderstorms may pose a hazard to boaters later this week into next weekend. Cooley/Eckberg
Special Weather Statement
National Weather Service Green Bay WI
658 AM CDT Mon Aug 10 2020
WIZ035-101300-
Wood WI-
658 AM CDT Mon Aug 10 2020
...SIGNIFICANT WEATHER ADVISORY FOR WOOD COUNTY UNTIL 800 AM CDT...
At 657 AM CDT, Doppler radar was tracking a cluster of strong
thunderstorms along a line extending from near Hatfield to near Coon
Valley. Movement was east at 40 mph.
Half inch hail and winds in excess of 40 mph will be possible with
these storms.
Locations impacted include...
Wisconsin Rapids, Pittsville, Babcock, Lake Wazeecha, Nekoosa, Port
Edwards, Biron, Vesper, Rudolph and Arpin.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Torrential rainfall is also occurring with these storms, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.
&&
LAT...LON 4453 9031 4458 8985 4451 8984 4451 8973
4425 8972 4425 9032
TIME...MOT...LOC 1157Z 263DEG 35KT 4440 9083 4374 9095
CooleyPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREEN BAY WI
803 AM CDT MON AUG 10 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0755 AM TSTM WND GST WISCONSIN RAPIDS 44.40N 89.84W
08/10/2020 M43.00 MPH WOOD WI ASOS
&&
RICHMPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREEN BAY WI
818 AM CDT MON AUG 10 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0735 AM TSTM WND DMG 5 N BABCOCK 44.37N 90.11W
08/10/2020 WOOD WI PUBLIC
LARGE TREE DOWN AT THE INTERSECTION OF HIGHWAY 80 AND 54.
DELAYED REPORT FROM SOCIAL MEDIA. TIME ESTIMATED BY
RADAR.
&&
BERSCHThe national radar mosaic for the moment the first event began.
2 thunderstorm wind. Local standard time, as filed.
Thunderstorm winds downed trees in Plainfield. The time of this report is an estimate based on radar data.
Thunderstorm winds downed trees near Wild Rose. The time of this report is an estimate based on radar data.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wisconsin in 2020Every state in 2020This day in weather historyWarnings in Wisconsin, August 2020
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: 902738, 902739.