158 FXUS63 KMKX 110224 AFDMKXArea Forecast Discussion National Weather Service Milwaukee/Sullivan WI 924 PM CDT Wed Sep 10 2025
.KEY MESSAGES...
- Areas of fog forecast tonight, with some locally dense fog possible west of I-39.
- Chances (~20-35%) for scattered showers and thunderstorms late Friday evening through Saturday morning.
- High temperatures climbing above normal late this week through the weekend, with humidity increasing as well.
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.UPDATE... Issued 924 PM CDT Wed Sep 10 2025
Cloud cover is started to slowly move south and dissipate over time this evening. While cloud cover is decreasing across southern Wisconsin you can see clouds building across Lake Michigan on satellite. This mid level clouds are preventing fog from developing across portions of Wisconsin and as cloud clear out patchy fog should expand. The best chances for fog will be low lying areas specifically river valleys, marsh lands etc. Not anticipating there to be much if any dense fog, but if clouds erode quickly, low lying areas west of Madison could get some patchy dense. Overnight lows are expected to fall into the low 50s in the west, which will make the dewpoint depressions lower. Versus the east which will have lows in the upper 50s to low 60s along Lake Michigan.
Patterson
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.SHORT TERM... Issued 256 PM CDT Wed Sep 10 2025
Tonight through Thursday night:
Synopsis/Mesoanalysis: Water vapor imagery places a broad upper trough over Lake Michigan this afternoon. Lift from the feature was responsible for light rain showers & sprinkles this morning, with regional radars continuing to depict light echoes over east-central and southeastern Wisconsin at the current hour. The majority of said echoes are struggling to reach the surface as they encounter a dry low level air mass, though occasional reports of light sprinkles have been noted. Any isolated sprinkles will push east of the region by late afternoon with the departing upper trough. Currently situated over the Northern Plains, an upper ridge will move into the upper Mississippi Valley tonight through Thursday, allowing high pressure currently centered over the Hudson Bay to drift southeast along the Ontario-Quebec border. This progression will allow for fair conditions and generally light surface winds through the duration of the short term period. The combination of mostly clear skies and light winds will be conducive for areas of fog development tonight, with the best potential likely to focus along and west of Interstate 39.
Tonight: With light winds and clearing skies, areas of fog development are possible after midnight. Tend to think that the best fog potential will focus along & west of I-39 (where skies will clear out the fastest), but can`t rule out some development as far east as the Kettle Moraine. Mesoscale model guidance is hinting at the possibility for locally dense fog along/west of I-39, though coverage & favored locations for development remain uncertain. Will thus be monitoring visibility trends through the overnight hours. Slow down, use low beam headlights, and allow for extra following distance if encountering fog while driving late tonight/early Thursday morning.
Quigley
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.LONG TERM... Issued 256 PM CDT Wed Sep 10 2025
Friday through Wednesday:
Synopsis: Rounding the upper ridge over the Mississippi Valley, a shortwave trough will cross the state Friday night into early Saturday morning, bringing chances for showers and thunderstorms to the region. Activity is forecast to shift south and east of the region after daybreak Saturday. The aforementioned upper ridge will slowly migrate into the western Great Lakes Saturday night into early next week, allowing for a prolonged stretch of largely dry conditions from Saturday afternoon through Monday. The ridge`s proximity will also translate to abundant sunshine, allowing for high temperatures to climb above normal from the second half of the weekend into early next week. Global forecast guidance indicates that upper ridging will begin to break down by mid-week, with some signal for trailing disturbances & returning precip chances during the Tuesday-Wednesday time frame.
Friday Night through Saturday: Expect showers and thunderstorms across the region from late evening into the predawn hours. Likely a testament to overnight timing, machine learning guidance is pointing toward low severe weather potential in this activity. Will nevertheless be monitoring trends as more CAM data becomes available over the next 12-24 hours. Precipitable waters will be increasing into the 1.3-1.5"+ range, which could translate to some brief heavy downpour potential in this activity.
Quigley
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.AVIATION... Issued 924 PM CDT Wed Sep 10 2025
Mid to upper level clouds across southern Wisconsin will slowly move south and dissipate tonight into early morning Wednesday. Overnight as clouds diminish, winds remain light and temperature drop there will be a potential for fog to develop. Low lying areas will have the best potential for patchy fog around 2-4 SM. Any dense fog that develop is likely to be in low lying areas west of Madison like LNR, but confidence is low on seeing visibilites of 1SM or less. Not every terminal will see the patchy fog, especially eastern airports. Winds will be light and variable through mid morning Wednesday.
VFR conditions will return to all airports shortly after sunrise when the fog burns off. Mostly clear skies in the morning will give way to some fair weather cumulus clouds around 4-6 kft in the afternoon and evening hours. Light easterly winds in the afternoon will become light and variable again Wednesday night.
Patterson
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.MARINE... Issued 256 PM CDT Wed Sep 10 2025
Weak low pressure of 1019 mb is centered over the Upper Peninsula of Michigan this afternoon, which is combining with 1025 mb high pressure near the Hudson Bay to support generally south to southeast winds across the open waters of Lake Michigan. The aforementioned high will settle near the Ontario-Quebec border on Thursday, allowing winds to shift out of the northeast tonight through Thursday afternoon. Light rain showers are possible through this afternoon. An isolated rumble of thunder can`t be ruled out, though hazards are not anticipated. Patchy fog is possible this evening through tonight, particularly across the northern half of Lake Michigan. Widespread dense fog is not anticipated, though trends will be monitored. High pressure will continue to move east into Quebec on Friday as 1006 mb low pressure moves into the northern Great Plains, allowing winds to turn southerly across the waters. Showers and embedded thunderstorms are expected Friday night into Saturday. Hazards aren`t currently anticipated in this activity, though trends will continue to be monitored in coming forecasts. Winds will turn back out of the northeast Saturday night through Sunday as 1026 mb high pressure settles along the Ontario-Quebec border.
Light south to southeast winds continue in nearshore zones through this afternoon, ultimately turning northeasterly tonight. Scattered showers are possible through this afternoon as an upper disturbance crosses the western Great Lakes. An isolated rumble of thunder is possible in this activity, though severe weather is not anticipated. Patchy fog is possible this evening and tonight. Widespread dense fog is not expected, though trends will be monitored. Low pressure will settle into the Northern Plains on Friday, allowing winds to shift back southerly. Scattered showers and thunderstorms are expected ahead of the low Friday night into Saturday. Small Craft Advisory conditions aren`t currently anticipated through the duration of the period.
Quigley
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.MKX WATCHES/WARNINGS/ADVISORIES... WI...None. LM...None. &&
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NWS MKX Office Area Forecast Discussion