textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Patchy frost & fog possible later tonight, particularly in low-lying spots away from Lake Michigan.

- Few sprinkles or light showers possible north of I-94 Saturday night, with otherwise dry weather into next week.

- Additional patchy frost possible Sunday night & Monday night.

SHORT TERM

Issued 1255 PM CDT Fri Oct 2 2026

This Afternoon through Sunday:

Synopsis/Mesoanalysis: High pressure is centered over central Minnesota this afternoon, and will continue to track east into southern Wisconsin during the overnight hours tonight. The approaching high will result in mostly to entirely clear skies, along with light/variable or entirely calm winds. The sky & wind conditions will allow for efficient radiational cooling and chilly low temperatures tonight. Patchy frost and fog are possible near daybreak, particularly in low-lying, inland areas. Move any cold- sensitive plants indoors before heading to bed this evening. High pressure will continue east on Saturday, allowing winds to trend south-southeasterly by late morning. Currently along the Washington- Oregon border, an upper disturbance will move into the Northern Plains on Saturday afternoon, progressing across Lake Superior Saturday night. A few light sprinkles or showers are possible within an attendant warm advection regime Saturday night, with most locations expected to stay dry. A cold front will cross southern Wisconsin during either the late morning or early afternoon hours on Sunday, with a dry frontal passage anticipated at this time.

Tonight: Boundary layer will be quick to decouple given clear skies and light to calm surface winds ahead of arriving high pressure. Thus anticipating that there will be patchy fog and frost around the area during the predawn hours, particularly in low-lying spots away from Lake Michigan. Development will be contingent on upper clouds currently over the Dakotas staying north of the area, with most model guidance in agreement regarding a more northerly track. Have thus leaned the forecast into one supportive of patchy fog & frost development by daybreak. Not anticipating fog to be dense enough nor frost widespread enough to warrant headlines. Slow down & use low beam headlights if encountering fog on the roads, and bring any cold- sensitive plants indoors.

Saturday night: Can't rule out a few light sprinkles or rain showers as warm advection increases ahead of a disturbance crossing Lake Superior. Best potential for precip will be north of I-94, where proximity to the disturbance will be greatest. Have introduced ~10- 15% precip probabilities over this part of the CWA in the afternoon update, and will continue to monitor for changes.

Sunday: Cold front will move across southern Wisconsin at some point during the late morning or early afternoon hours. Marginal convergence at the front & an absence of any forcing mechanisms aloft point toward a dry frontal passage at this time. Will nonetheless monitor for possible changes through tomorrow.

Quigley

LONG TERM

Issued 1255 PM CDT Fri Oct 2 2026

Sunday night through Friday:

Synopsis: Settling in behind the Sunday front, the next area of high pressure will move across the western Great Lakes during the Sunday night to Tuesday morning time frame. Presence of the high will promote light surface winds and mostly clear skies for the beginning of the work week. The combination of sky and wind conditions will be favorable for efficient radiational cooling both Sunday night and Monday night, with areas of frost possible. High pressure will vacate to the east of the area on Tuesday afternoon, with the next upper disturbance moving into the western Great Lakes Tuesday night into Wednesday. Said disturbance will pull a cold front across southern Wisconsin either late Tuesday night or early Wednesday morning. Precip appears unlikely along the front at this time. Mild, Fall-like weather will prevail through the second half of the work week behind the departing cold front.

Sunday night & Monday night: A newly-arrived Canadian air mass & settling high pressure will create favorable conditions for efficient radiational cooling and chilly overnight lows. Current forecasts from the NBM point toward low temps in the upper 30s to near 40 away from Lake Michigan, which appear reasonable for the time-being given the set up. Will be monitoring for slight downward adjustments as this portion of the period draws closer, particularly in the traditionally cooler spots toward central Wisconsin, where probabilistic guidance is indicating ~20% chances of overnight lows at or below 36. Given expected conditions, will need to watch for areas of frost during each overnight period. Whether or not any frost will be widespread enough for headlines remains uncertain at this time, with trends being monitored into early next week. Be sure to move any cold-sensitive plants indoors during each overnight period.

Tuesday night into Wednesday morning: Will be monitoring for possible light rain chances along a passing cold front. Realization of precip will be fighting a number of limiting factors, including very dry pre-frontal air & marginal frontal convergence/lift. Have thus continued a dry forecast in the mid-day update, which aligns well with NBM precip probabilities near 5%. Will continue to evaluate for possible changes as this part of the period pulls closer.

Quigley

AVIATION

Issued 1255 PM CDT Fri Oct 2 2026

VFR flight categories prevail through the period at all terminals. Widely scattered cumulus clouds based near FL050 may attempt to develop along a weak lake breeze later this afternoon in southeast Wisconsin, with any clouds clearing after sunset. Will need to monitor for scattered lake effect clouds later tonight, though confidence is too low to justify mentions in the 18Z update. Shallow ground fog is possible near daybreak Saturday, particularly in low- lying inland areas, with confidence once more too low to justify any mentions in the current forecast. Will be monitoring observational trends for possible amendments through tonight. High pressure will move overhead this evening, resulting in calm or light/variable winds. Winds will trend south-southeasterly Saturday morning as the high moves east of the region.

Quigley

MARINE

Issued 1255 PM CDT Fri Oct 2 2026

1026 mb high pressure will move across Lake Michigan this evening, bringing decreasing & eventually light/variable winds. Winds will trend south-southwesterly Saturday as 1010 mb low pressure moves toward the Hudson Bay from the Canadian Prairies. The low will pull a cold front across the waters Saturday night into Sunday, bringing a west-northwest wind shift. Showers could accompany the passing front, particularly across the northern half of the waters. Northwest winds will continue through the day Monday, tapering Monday night as 1024 mb high pressure moves in from the northern Great Plains.

A deeper area of 994 mb low pressure will build toward the Hudson Bay Tuesday through Thursday. South-southwest winds will increase in advance of the approaching low Tuesday afternoon through Wednesday, becoming gusty at times. While not currently expected to be widespread, a few gusts could approach gale-force, particularly over the northern half of the open waters. Will be monitoring for possible headlines as this portion of the period draws closer. The low will pull a cold front across the waters Wednesday night into Thursday, bringing a west-northwest wind shift and scattered rain showers. Best potential for rain is currently favored over the northern third of the open waters. Generally westerly winds will continue through Friday as 1020 mb high pressure moves near or just south of Lake Michigan.

Small Craft Advisory conditions are possible Tuesday afternoon and night ahead of the next area of low pressure. Will be monitoring for potential headlines as this portion of the period draws closer.

Quigley

MKX WATCHES/WARNINGS/ADVISORIES

WI...None. LM...Small Craft Advisory...LMZ646 until 1 PM Friday.