A strong warm front allowed temperatures to rise into the 90s to low 100s with dew points in the middle 70s to lower 80s across much of central and east-central Wisconsin on Wednesday (8/23). The combination of hot temperatures and high dew points allowed heat index values to soar from 100 to 117.
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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 strong warm front allowed temperatures to rise into the 90s to low 100s with dew points in the middle 70s to lower 80s across much of central and east-central Wisconsin on Wednesday (8/23). The combination of hot temperatures and high dew points allowed heat index values to soar from 100 to 117.
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 23, 5:35 AM CST, 4 hours 25 minutes earlier.
Area Forecast Discussion National Weather Service Green Bay WI 635 AM CDT Wed Aug 23 2023 Updated aviation portion for 12Z TAF issuance .SHORT TERM...Today...Tonight...and Thursday Issued at 401 AM CDT Wed Aug 23 2023 Showers and a few thunderstorms moved across northern Door County near Washington Island earlier this morning. The activity has moved east of the area. Looking at the surface map, a warm front extended from south of Hayward to northeast of Eau Claire into central Wisconsin to near Fond Du Lac and then southeast to the lakeshore. Temperatures north of the warm front were in the 60s with low clouds. South of the warm front, temperatures were well into the 70s with dewpoint readings in the middle to upper 70s across southwest of Wisconsin. For today, the warm front is expected to lift north of Wausau and Green Bay, but not as far north as the models indicated yesterday. This will lead to a fairly large range in high temperatures since the north may stay mostly cloudy much of the day. High temperatures will range from the upper 70s to lower 80s across far north- central Wisconsin to near 100 across portions of central Wisconsin. Since the front is not expected to go as far north, this will lead to a quicker shift in the winds and cooler air advecting into the area, especially near Green Bay where winds may shift to the northeast and would experience a fairly rapid cool down with the winds off the bay. There are still some model differences in the wind shift south of Highway 29, but the heat index values should be below 100F by 7 pm. For the four counties in the Excessive Heat Warning, continued the 9 pm end time until the heat index values drop below 100F. There is a small chance of a thunderstorm across east-central Wisconsin this afternoon. If any storm did develop it would produce gusty winds, brief heavy rain and small hail. For tonight, it will turn cooler along with some patchy fog. There is a small chance of a shower or thunderstorm after midnight. Low temperatures will be in the 60s. There is a continued small chance of a shower or thunderstorm across northeast Wisconsin on Thursday. Under partly cloudy skies, highs will range from the upper 70s to lower 80s north to near 90 across central Wisconsin. .LONG TERM...Thursday Night Through Tuesday Issued at 401 AM CDT Wed Aug 23 2023 The main highlights from this forecast period revolve around the potential for showers and thunderstorms Friday afternoon/evening, cooler and drier conditions for the weekend, and possibly another chance for showers and storms early next week. Thursday night through Friday night...Quiet conditions will start this period with high pressure overhead. By midday Friday, a mid- level shortwave, in concert with a surface cold front, will move over northern MN/western Lake Superior. Ahead of this front, low- level WAA will increase across the forecast area. As the front moves southeast across the forecast area late Friday afternoon into Friday evening, it will coincide with MUCAPE of 600 to 900 J/kg and 0-6km shear of 50 to 60 kts. These severe parameters will bring a marginal risk for a few strong storms capable of producing hail and gusty winds, especially in north-central WI. The severe threat would decrease with time as instability wanes into the evening. Rest of the extended...Before high pressure drops into the region for the weekend, models indicate a tighter pressure gradient developing following the frontal passage Friday evening into Saturday. As a result, gusty northeast winds in far eastern WI may pose a threat to small craft on the bay and lake on Saturday. Winds will gradually decrease as the high pressure center moves closer/over the region Saturday evening/night. Otherwise, cooler and drier conditions are expected for Saturday and Sunday with highs in the low to middle 70s. Models indicate the next chance for showers and storms arrives on Monday with a digging shortwave/trough and cold frontal passage. The precip may linger into Tuesday as the trough slowly exits. && .AVIATION...for 12Z TAF Issuance Issued at 622 AM CDT Wed Aug 23 2023 MVFR and IFR or lower CIGS developed north of a warm front draped across central Wisconsin into the southern Fox Valley early this morning. The warm front is expected to move north of KAUW to KGRB this morning and then stall. Low clouds will probably linger through the day north of the stalled warm front. The low CIGS should clear of most location along and south of Highway 29 this morning. South of the warm front, VFR conditions are expected through much of the afternoon until the front pushes south as a cold front later this afternoon into early this evening. As front drops south, have trended pretty hard on low clouds and fog through much of the night into early Thursday morning based on upstream observations. For the KGRB TAF site, models are indicating an abrup wind shift later this afternoon between 21z and 00z tonight. Southwest winds of 10 to 20 knots could veer to the northeast during this time frame. Conditions should gradually improve on Thursday. && .GRB WATCHES/WARNINGS/ADVISORIES... Heat Advisory from 10 AM this morning to 7 PM CDT this evening for WIZ020-030-031-037>040-049-050-074. Beach Hazards Statement until 3 PM CDT this afternoon for WIZ022- 040-050. Excessive Heat Warning from 10 AM this morning to 9 PM CDT this evening for WIZ035-036-045-048. && SHORT TERM.....Eckberg LONG TERM......Kruk AVIATION.......Eckberg
Hazardous Weather Outlook National Weather Service Green Bay WI 602 AM CDT Wed Aug 23 2023 WIZ005-010>013-018>022-030-031-035>040-045-048>050-073-074-241115- 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- 602 AM CDT Wed Aug 23 2023 This Hazardous Weather Outlook is for north-central and northeast Wisconsin. .DAY ONE...Today and Tonight Hot and humid weather is expected today. Heat index values of 100 to 110 degrees are likely in central and east central Wisconsin, where Excessive Heat Warnings or Heat Advisories are in effect. High waves will bring an increased risk of rip currents to beaches on the Lake Michigan shoreline through into early afternoon. There is a chance of thunderstorms across far northeast Wisconsin this morning. Brief heavy rain and small hail are possible with the stronger storms. There is a chance of thunderstorms late this afternoon and early this evening across east-central Wisconsin. If any storms do develop, they could contain small hail, gusty winds and brief heavy rain. Fog may restrict visibilities for motorists tonight into early Thursday morning. The fog may be locally dense with visibilities below a half mile. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday There is a chance of thunderstorms on Thursday across north- central and far northeast Wisconsin. Severe storms are not anticipated at this time. There is another chance of thunderstorms on Friday. An isolated strong storm capable of producing hail and gusty winds is possible in far north-central Wisconsin. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected today or tonight. LMZ521-522-541>543-241115- The Bay of Green Bay south of a line from Cedar River MI to Rock Island Passage-Lake Michigan from Washington Island to Sheboygan- 602 AM CDT Wed Aug 23 2023 This Hazardous Weather Outlook is for portions of northwest Lake Michigan and the waters of Green Bay. .DAY ONE...Today and Tonight Gusty south winds and high waves will result in hazardous conditions for small craft on Lake Michigan through midday. Fog may restrict visibilities for mariners tonight into early Thursday morning. There is a chance for thunderstorms late tonight north of Algoma that could pose a hazard to mariners. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday There is a chance for thunderstorms on Thursday and Friday, which could pose a hazard to mariners. Eckberg/Kruk
Special Weather Statement National Weather Service Green Bay WI 651 AM CDT Wed Aug 23 2023 WIZ018>020-030-031-035>039-045-048-049-231330- Lincoln-Langlade-Menominee-Marathon-Shawano-Wood-Portage-Waupaca- Outagamie-Brown-Waushara-Winnebago-Calumet- 651 AM CDT Wed Aug 23 2023 ...FOG MAY IMPACT TRAVEL EARLY THIS MORNING... Areas of fog have developed across central into east-central Wisconsin early this morning. Visibilities were generally in the 1 to 3 mile range, however there were pockets of locally dense fog with a visibility of a quarter of a mile or less. Surface observations indicated that dense fog was occurring at Wausau, Stevens Point, Wautoma and Waupaca. The fog through linger through 8 am and then burn off by mid to late morning. If you encounter dense fog, slow down and use your low beam headlights. Allow extra space between you and the car in front of you. Eckberg
The national radar mosaic for the moment the first event began.
10 excessive heat. Local standard time, as filed.
The combination of hot temperatures and high humidity caused heat index values to rise as high as 108 degrees from the late morning through the afternoon.
The combination of hot temperatures and high humidity caused heat index values to rise as high as 117 degrees from the late morning through the early evening.
The combination of hot temperatures and high humidity caused heat index values to rise as high as 116 degrees from the late morning through the early evening.
The combination of hot temperatures and high humidity caused heat index values to rise as high as 113 degrees from the late morning through the afternoon.
The combination of hot temperatures and high humidity caused heat index values to rise as high as 110 degrees from midday through the early evening.
The combination of hot temperatures and high humidity caused heat index values to rise as high as 111 degrees from midday through the early evening.
The combination of hot temperatures and high humidity caused heat index values to rise as high as 106 degrees during the afternoon.
The combination of hot temperatures and high humidity caused heat index values to rise as high as 110 degrees from the early afternoon through the early evening.
The combination of hot temperatures and high humidity caused heat index values to rise as high as 108 degrees during the afternoon.
The combination of hot temperatures and high humidity caused heat index values to rise as high as 113 degrees from the early afternoon through the early evening.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wisconsin in 2023Every state in 2023This day in weather historyWarnings in Wisconsin, August 2023
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: 1120266, 1120267, 1120269, 1120276, 1120270, 1120272, 1120280, 1120275, 1120277, 1120273.