textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Light freezing drizzle & freezing rain remain possible tonight, particularly to the north of I-94. A light glaze of ice can't be ruled out on elevated and untreated surfaces.

- Gradual warming trend expected through the end of the week.

SHORT TERM

Issued 1120 PM CDT Wed Mar 18 2026

Rest Of Tonight through Saturday:

Synopsis/Mesoanalysis: A weak disturbance is in moving into northeast and east-central Wisconsin late this evening, encouraging a scattering of radar echoes from southern Lake Michigan northwest into central Wisconsin. The passing disturbance will encourage additional light precip development primarily north of I-94 through the predawn hours, with surface temperatures supportive for some freezing rain and drizzle. A light glaze of ice is possible in areas experiencing freezing rain/drizzle, particularly on elevated and untreated surfaces. Budget a few extra minutes of travel time if taking to the roads north of I-94 through sunrise. Northwesterly upper level flow will continue to influence weather conditions across the region through the conclusion of the period, with embedded disturbances encouraging areas of low pressure development & frontal passages at the surface. A disturbance & surface low will progress across northern Lake Michigan Thursday night into Friday, with a cold front crossing southern Wisconsin on Friday morning. Broad low pressure will build over the Northern Plains on Saturday, with southwesterly winds allowing for mild high temperatures.

Rest Of Tonight into Thursday Morning: Will be monitoring for additional areas of light precip through daybreak. Evidenced by 00Z mesoscale guidance & mid-late evening radar trends, it continues to appear that the best chances for precipitation will remain to the north of I-94 through the remainder of the overnight period. Forecast soundings do hint at brief periods of saturation between ~2- 7 AM further southwest/into the I-94 Corridor, however, so have maintained slight (~10-20%) precip probabilities as far south as Madison & the southeast Wisconsin metro areas. Temperatures have hovered just above freezing in many spots through this evening, but do anticipate that there will be areas of sub-freezing temperatures materializing through daybreak. Thus will be watching for freezing rain/drizzle in areas that do dip below the freezing mark, with rain/drizzle prevailing in warmer locations. Can't rule out a light glaze of ice in locations seeing freezing rain/drizzle, especially on elevated and untreated surfaces. Precip will push southeast of the area between ~4-7 AM. Some patchy fog is possible during the morning commute. Don't expect dense fog at this time, but will nevertheless be monitoring trends.

Thursday Night: The next disturbance will be passing to the northeast of the area, bringing widespread precipitation to northeast Wisconsin and the Upper Peninsula of Michigan. Currently expect conditions to remain dry in southern Wisconsin, but will need to watch precip trends over the northeastern CWA. Should the responsible disturbance trend slightly southwest of its current track, precip probs may become necessary in later forecasts. Conditions would be mild enough for all rain in the event precip snuck into the far northeast.

Saturday: Continue to expect the mildest day of the entire forecast period as south-southwest winds pull warm air in from the Central Plains. Have maintained NBM temperature forecasts in the evening update, with the understanding that values may trend cooler closer to Lake Michigan given a likely lake breeze during the afternoon hours. While it's expected to stay out of southern Wisconsin through the afternoon hours, progression trends regarding a cold front lingering just north of the region will also need to be watched. If the front's arrival were to speed up, temperatures would trend cooler from the current forecast areawide.

Quigley

LONG TERM

Issued 1120 PM CDT Wed Mar 18 2026

Saturday night through Tuesday:

West northwest flow at 500 mb Saturday night will give way to a broad trough shifting through the region later Sunday into Sunday night. The main differential CVA from this looks to remain to the north of the area. Ensembles suggest a stationary boundary ahead of a surface low should gradually shift south of the area later Saturday night into Sunday, with the surface low following the frontal boundary.

There may be some surface to 850 mb and 850 mb to 700 mb frontogenesis response that shifts south through the area during this period, which may combine with some deep moisture to bring some chances (around 20 to 30 percent, highest north and northeast parts of the area) for light rain, with some light rain and light snow mix possible in northern portions of the area.

The precipitation chances will depend on the low track and available moisture to work with. Ensemble mean probability of 0.01 inches of precipitation are highest toward northern and northeastern parts of the area, lower to the southwest. North winds on the backside of the low bring cold air advection into the area Sunday and Sunday night, with drier conditions returning.

Ensembles then bring high pressure across the region Monday into Monday night, with dry conditions and seasonable temperatures. More uncertainty exists with the next frontal boundary that may shift south through the area Tuesday, as moisture may be lacking. May keep forecast dry for now.

Wood

AVIATION

Issued 1120 PM CDT Wed Mar 18 2026

VFR flight categories prevail across southern Wisconsin late this evening. Developing in advance of an approaching disturbance, -RADZ and -FZRADZ remain a possibility mainly north of I-94 through the remainder of the overnight hours, with precip type ultimately depending on local air temperatures in the vicinity of aerodromes. Have withdrawn any mentions of precipitation in the coming 06Z update at KENW and KMSN given model guidance and radar trends through this evening. Have maintained PROB30 groups at UES and MKE. Expect the majority of precip to pass north of the two aforementioned terminals, but can't entirely rule out some light activity during the predawn hours. Should activity continue to remain north, mentions will be removed in coming amendments. A combination of near-term TEMPO and prevailing groups have been inserted at SBM in the coming 06Z forecast, where confidence in measurable precipitation is highest.

Can't rule out some patchy FG early Thursday morning following the conclusion of precipitation, particularly at western terminals. Have thus continued BR groups at MSN and JVL in the 06Z update. Any VIS reductions should improve by late morning Thursday. VFR flight categories will prevail through Thursday afternoon, with possible reductions returning later Thursday night. Could also see some LLWS in advance of an approaching surface front Thursday night, with mentions being inserted near the end of the 30 hour period at MKE in the coming 06Z forecast.

Quigley

MARINE

Issued 1120 PM CDT Wed Mar 18 2026

1010 mb low pressure is positioned over Ontario late this evening, resulting in generally southwest winds across the open waters of Lake Michigan. Said low will advance toward the southern Hudson Bay through daybreak as 1018 mb high pressure builds into Wisconsin from the northern Great Plains. Thus anticipate that the current southwest winds will trend light and variable by daybreak, with variable winds continuing through Thursday morning. Some light rain is possible over the southern half of the open waters through sunrise. A new area of 1006 mb low pressure is forecast to develop in the Canadian Great Plains Thursday afternoon, allowing winds to turn east-southeasterly across Lake Michigan. Winds will veer south to southwesterly across the waters Thursday night as the surface low progresses over or just north of the northern half of Lake Michigan. Some rain or snow is possible over northern Lake Michigan during the low's passage, with wind gusts expected to remain below gale thresholds. Winds will turn west-northwesterly on Friday as a cold front moves across the waters.

Winds will become light Friday night through Saturday morning as 1016 mb high pressure moves across Lake Michigan. Increasing southerly winds are expected Saturday afternoon as a cold front approaches from the north. The front is expected to cross Lake Michigan Saturday night into Sunday morning, bringing gusty northerly winds into Monday morning. Rain and snow showers will accompany the passing cold front. Widespread gales are not anticipated at this time, though trends will be monitored over coming forecasts. Winds will decrease Monday night, ultimately turning southerly and increasing once again during the day on Tuesday.

Winds and waves will approach Small Craft Advisory levels in nearshore zones Saturday night through Monday morning as a cold front works across Lake Michigan. While not currently expected to be widespread, a few gusts approaching gale force are possible during the day Sunday. Expect that headlines will become necessary as this portion of the period draws closer. Following a brief lull in wind gusts Monday evening & night, readings will increase and potentially approach advisory levels during the day Tuesday, particularly in northern nearshore zones.

Quigley

MKX WATCHES/WARNINGS/ADVISORIES

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