textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Patchy fog lingers into the overnight hours, with some dense fog possible in low lying areas.

- Warmer temperatures are expected by Saturday.

- Next chances for precipitation mainly Saturday night into Sunday.

UPDATE

Issued 333 AM CDT Fri Mar 20 2026

Southwest winds have increased during the early morning hours which has diminished some of the fog. Patchy fog is still visible on the Night time fog channels and through the scattered mid to upper level cloud deck. Can't rule out some patchy dense fog, but this would be in sheltered low lying areas.

There are some very light radar returns across the northeastern corner of the forecast areas as the sfc low moves through the northern mitten (northern Lower Michigan). Looks like there just enough lift to try to squeeze out some drizzle. Temperatures are well above freezing in the upper 30s to low 40s so there's no major impacts expected. Drizzle that actually makes it to the ground will be sporadic with lakeshore areas have the best chances. This is do to low level dry air that remains in place for inland areas. Dew point depressions around 5 to 10 degrees in Fond du Lac, Plymouth, and Kewaskum (both from ASOS and Wisconet) while the Sheboygan ASOS's dewpoint depression is 3 degrees. Overall a quiet Wisconsin morning.

Patterson

SHORT TERM

Issued 1210 AM CDT Fri Mar 20 2026

Overnight through Monday:

Middle to high clouds should continue to push southeastward through the area overnight into Friday morning. Patchy fog continues for eastern portions of the area as well, and may develop across areas north of Madison. There may be some dense fog in localized or low lying areas into the overnight hours.

The fog should linger into the overnight hours, until south to southwest winds develop around 09Z Friday and combine with the clouds to help gradually dissipate the fog. There is some uncertainty with the fog completely dissipating, so trends will need to be monitored overnight.

An area of low stratus clouds should push southward into the area Friday afternoon. This is despite high pressure over the region keeping winds fairly light. This low cloud deck may linger into Friday night, though confidence is low at this time with how long this low cloud deck may linger.

Temperatures Friday will depend on how soon the low clouds move in, and should vary quite a bit from west to northeast parts of the area. For now, have highs in the lower to middle 60s toward Dodgeville and Darlington, and middle 40s toward Fond du Lac and Sheboygan, and 50s elsewhere. Confidence in the temperature forecast is low at this time.

For now, kept the forecast mostly cloudy for Friday night with the low clouds lingering, and finally push them northeast of the area Saturday. Warm air advection on increasing south to southwest winds Saturday should bring warmer temperatures into the area. Highs may reach into the 60s over most of the area, perhaps reaching 70 degrees or more west of Madison. Temperatures may be in the 40s to around 50 toward Sheboygan and Port Washington, where winds may remain onshore.

Models and ensembles are trending southward somewhat with the surface low track for Sunday, taking it across central Illinois into Indiana. As the warm front develops south of the area, winds should shift to the north and northeast Saturday night into Sunday, with cold air advection brining cooler temperatures. There may be some low clouds that move into the area as well from the north. There is some surface to 850 mb and 850 mb to 700 mb frontogenesis response that shifts southward through the area Saturday night into Sunday.

Forecast soundings are rather mixed with the amount of deep moisture available during this time, with generally light QPF values shown in ensemble members. The probability of measurable precipitation during that time varies as well, with northeast areas generally having the higher probabilities. Temperatures should be warm enough for rain during this time.

For now, will leave the NBM PoPs of 20 to 30 percent going for later Saturday night into Sunday morning, and wait and see how the moisture profiles evolve with later model/ensemble runs.

High pressure moving into the region should bring quiet weather back to the area for Sunday night and Monday. Temperatures should be near normal values.

Wood

LONG TERM

Issued 1210 AM CDT Fri Mar 20 2026

Monday night through Thursday:

Synopsis: Low pressure will move from the Canadian Prairies into Ontario Monday night through Tuesday, dragging a cold front across southern Wisconsin at some point Tuesday morning or afternoon. With dry antecedent air in place ahead of the front, and marginal at best moisture return to the encroaching front, current expectations are for a dry frontal passage. With a quick return of south-southeast winds Wednesday, no major cool down is expected in the wake of the Tuesday frontal passage.

A more expansive area of low pressure will develop over the Northern Plains Wednesday afternoon and evening, ultimately moving into eastern portions of the continent Thursday into Thursday night. The low progression will allow another cold front to cross the region at some point during the day on Thursday, with spread regarding the precise timing of the frontal passage still apparent in global ensemble guidance. With better moisture return ahead of this second surface front, anticipate that precip will return to the forecast over at least parts of southern Wisconsin on Thursday.

Tuesday: While currently expected to be a dry frontal passage, will be monitoring the evolution of precip forecasts in coming forecast updates. Precip-free forecast is being driven by a loose consensus of solutions amongst Canadian and ECMWF guidance, which suggest that conditions will remain too dry for precip as the front is passing through. There has been run to run consistency, however, for better moisture return and some light precip potential in forecasts from the GEFS. In the event precip probabilities increase in later updates, it would be due to the scenario depicted in the GEFS becoming favored across the entire guidance suite.

Thursday: Looking at better precip potential over at least parts of southern Wisconsin as a second cold front moves through. Current temperature forecasts suggest that precip would fall as all rain, though trends will need to be monitored over coming updates.

Quigley

AVIATION

Issued 1210 AM CDT Fri Mar 20 2026

Middle to high clouds should continue to push southeastward through the area overnight into Friday morning. Patchy fog continues for eastern portions of the area as well, with generally 2 to 5 mile visibility values. Patchy fog may develop across areas north of Madison as well. There may be some dense fog in localized or low lying areas into the overnight hours.

The fog should linger into the overnight hours, until south to southwest winds develop around 09Z Friday and combine with the clouds to help gradually dissipate the fog. There is some uncertainty with the fog completely dissipating, so trends will need to be monitored overnight.

Low level wind shear conditions are also expected overnight into early Friday morning across the area, with southwest to west southwest winds around 40 knots at 2000 feet AGL.

An area of low stratus clouds around 1000 to 1500 feet AGL should push southward into the area Friday afternoon. This is despite high pressure over the region keeping winds fairly light. This low cloud deck may linger into Friday night, though confidence is low at this time with how long this low cloud deck may linger.

Wood

MARINE

Issued 1210 AM CDT Fri Mar 20 2026

South to southwest winds are expected to develop overnight, as low pressure around 29.7 inches progresses southeast into northern Lower Michigan. Winds will shift to northwest to north Friday morning, as a cold front shifts southeast across the lake. Winds become light Friday night, as high pressure around 30.3 inches builds into Ontario.

Low pressure around 29.5 inches develops in the lee of the Wyoming Rockies Saturday morning, shifting winds south. The low should move southeastward Saturday night, allowing winds to increase and shift to the north and northeast across the northern half of the lake.

The low should move across central Illinois into Indiana Sunday, as it deepens to around 29.4 inches. This should lead to northerly winds backing to northwesterly Sunday into Sunday night across the lake. A few gales are possible during this timeframe, mainly over southern portions of the lake. A Small Craft Advisory may be needed Sunday into Monday for the nearshore waters, for gusty winds and building waves.

High pressure around 30.5 inches should then bring decreasing winds for Monday.

Wood

MKX WATCHES/WARNINGS/ADVISORIES

WI...None. LM...None.