textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Widespread rain expected tonight. Some rain-snow mix is possible at times, mainly north of I-94, with any accumulation remaining light (1 inch or less) if applicable. Snow showers along the cold front are possible late tonight into Friday morning, and may cause a brief drop in visibility and slick spots on the Friday AM commute.

- A High Wind Warning is in effect 4 AM to 4 PM CDT Friday. West to northwest winds with gusts up to 60 MPH are expected behind a cold front.

- A Storm Force Wind Warning is in effect for the southern half of Lake Michigan tonight through Friday due to gusty winds ahead of and behind the cold front. Gales are expected for the rest of the lake.

- Confidence is increasing for significant accumulating snow, blowing snow, and wintry mix Saturday night through Monday afternoon. A Winter Storm Watch has been issued. There does remain some uncertainty with the exact track of the low along with resultant precipitation types and totals. Pay close attention to the forecast if planning travel during this time frame.

SHORT TERM

Issued 305 PM CDT Thu Mar 12 2026

Tonight through Friday night:

A clipper system will track eastward across northern WI overnight, with both the WAA this evening into tonight and CAA late tonight into Friday morning leading to precip chances (80-95% and 20-40% respectively). As the associated clouds push in from the west this afternoon, we may see some virga as low level dry air evaporates the initial precip. Forecast soundings indicate we should begin to see surface precip sometime after 7 PM this evening (starting with Lone Rock / WI Dells / Montello) and spreading southeastward to reach the MKE metro no later than 1 AM Friday. Though the LLJ's warm nose (as seen on forecast soundings) does not exceed the freezing mark and we're fairly confident in the presence of cloud ice through the WAA phase, the lowest ~2,000 ft of the atmosphere should remain above freezing (particularly for the southern half of the CWA), same with the surface temperatures. As such, this is predominantly a rain event, with some wet snow mixing in (mainly further north towards central / east-central WI). For the CAA phase of the event (late tonight into Friday morning), we're expecting to lose most (if not all) of that shallow above-freezing layer, though cloud ice is a bit less certain. With strong FGEN and small (but noticeable) positive buoyancy energy along the front, we can't rule out convective snow showers or weak snow squalls along it. We're only affording it 20-40% precip chances given that the coverage would be scattered at best, but the main window for this activity would be 4 AM to 9 AM Friday (for nearly all of the CWA except far southwestern WI), though east-central WI could observe a second round of showery activity as late as mid-day Friday. When all is said and done, we're looking at slushy accumulations of only a fraction of an inch possible, with locally higher totals around 1 inch possible towards east-central WI. Any localized convective snow showers / squalls would be capable of dropping this ~1 inch of snow in a quick ~1 hour window. A few slick spots will be possible for the Friday AM commute, especially further north.

The west to northwest winds behind the cold front are expected to be gusty, and a High Wind Warning has been issued for the entire CWA from 4 AM to 4 PM CDT Friday. Though the worst of the gusts may only last for a fraction of this entire window, the ingredients for gusts up to 60 MPH will be present. Highest confidence in criteria-level gusts is the southwestern two thirds of the region, with the lowest confidence (slightly slower gust potential) towards east-central WI. Downed tree branches and power outages could easily occur.

High temperatures in the upper 30s to low 40s Friday afternoon. As high pressure sags southeastward into the region into Friday evening, wind gusts will rapidly decrease. Clouds might briefly scatter apart Friday afternoon / evening for all or part of the region, but then rebuild into Friday night ahead of the next system.

Sheppard

LONG TERM

Issued 305 PM CDT Thu Mar 12 2026

Saturday through Thursday:

Confidence remains high that a significant winter storm will impact the region this weekend, with a swath of heavy snow likely along with strong winds. As is common with deepening/phasing systems like this, big questions remain with the track of the low and timing of the phasing, which will impact where the swath of heaviest snow sets up. Additionally, models have trended toward taking the 850 mb low farther north into the southern forecast area, bringing an area of warmer air aloft into areas along/south of I-94. This could result in a period of freezing rain, sleet, and rain mixing in for these southern areas. Models are remaining south with the surface low though, with deterministic and ensemble mean tracks roughly through or to the south of Chicago. Given these variables, there remains a fair amount of uncertainty in terms of local wintry precip impacts. That said, this storm has a high impact potential for areas that take the brunt of this system. This is due the potential for prolonged heavy precip rates, period of wintry mix, and strong winds. With the high impact potential and start of the system a little over 48 hours out, opted to go with a Winter Storm Watch for the entire forecast area. Highest confidence in impacts from snow and blowing snow is currently north of I-94, with the higher confidence in wintry mix along/south of I-94. Strong winds will be a concern across southern Wisconsin.

Here are a few things to keep an eye on over the next couple days. The first thing to watch are the surface and 850 mb low tracks. Given the expected transition from rain to mixed precip to very heavy snow over a fairly short distance with this deepening low, any wobble north/south with the low tracks would have a significant impact on local precip types/amounts. As mentioned already, while the surface low track has remained fairly steady, the 850 mb low has been trending northward. Another trend to watch is that models have been slower with the exit of this system, lingering into at least Monday morning with the moderate to heavy snow and blowing snow. This would bring the higher impacts into the Monday morning commute. Lastly, models are often on the high side with storm total liquid equivalent 2-4 days out. Given the current anomalously high storm totals for a winter storm, it will be worth watching if models start coming down with totals in the next 24-48 hours. Give the strength of this system though, liquid equivalent totals of 1-2 inches seem reasonable, maybe not upwards of 3" per 12Z deterministic models.

Colder and drier conditions are expected to settle into the region behind the departing strong low early next week, as high pressure moves in from the northwest. Below normal temps are likely Monday and Tuesday, with temps moderating towards normal by mid-week. Dry weather is expected Mon/Tue, with a chance for rain/snow Tue night into Wed as a shortwave drops through the area.

DDV

AVIATION

Issued 305 PM CDT Thu Mar 12 2026

Sig Weather: As a clipper system passes north of our region tonight we expect light stratiform rainfall this evening (with light snow mixing in, mainly further north), followed by showery (off an on) precip at scattered coverage (20-40% chances) continuing late tonight into Friday morning, gradually retreating northeastward by midday. This 'showery' precipitation window may be characterized by a rain/snow mix (especially further north), with some potential for embedded convective snow showers or even weak snow squalls. Slushy accumulations of 1 inch or less expected, with little to no accumulation further south in our region. Timing will be reflected in the TAFs, with convective showery snowfall included as just a PROB30 group for now, omitted from terminals further south.

Winds: The main story with this system will be the gusty winds. The existing light westerly winds this afternoon will turn south and rapidly accelerate this evening, with gusts up to 30 to 40 knots possible later this evening through Midnight. From 3 to 6 AM CDT Friday, a cold front will sweep west to east across the region, with gusty west winds arriving behind it. A High Wind Warning is in effect for the entire region from 4 AM to 4 PM Friday due to gusty west to northwest winds behind the cold front, with gusts up to 50 kt. Northwest winds will gradually subside Friday evening, becoming light and variable by late Friday night.

Cloud Ceilings: VFR expected to continue through the rest of the afternoon and much of the evening. As observed in METARs to our west, the approaching cloud ceilings ahead of the precip tonight appear to be at or above the 6,000 ft level. As precip moves in (7 PM today thru 1 AM CDT Fri), ceilings should gradually decrease in altitude, with the north half or two thirds of our CWA likely dropping to 1,000 to 3,000 ft Fuel Alt / MVFR ceilings. These ceilings could easily linger through much of the day Friday, but should lift or scatter back to VFR by late Friday afternoon.

Sheppard

MARINE

Issued 305 PM CDT Thu Mar 12 2026

Very active conditions are anticipated across the open waters from tonight through the beginning of next week. Currently in the northern Great Plains, 990 mb low pressure will approach and cross the northern half of Lake Michigan tonight through Friday morning. Southerly winds will quickly increase as the low approaches tonight, ultimately veering westerly to northwesterly as it moves into Ontario Friday evening. Widespread gale force gusts remain forecast across the northern half of the open waters, where a Gale Warning remains in effect between 10 PM CDT tonight and 10 PM CDT Friday evening. Even stronger gusts are expected across the southern half of the open waters, where confidence has increased in widespread storm force gusts in this forecast. A Storm Warning has thus been issued for southern Lake Michigan between 10 PM CDT tonight and 10 PM CDT Friday evening. It's possible that winds could decrease below storm thresholds prior to the current 10 PM CDT Friday expiration of the Storm Warning. If necessary, any early cancellations will be handled as winds decrease Friday evening. Areas of rain and snow will accompany passing low pressure tonight. Areas of light to occasionally moderate freezing spray are possible over northern Lake Michigan Friday afternoon.

Winds will taper away from headline thresholds later Friday night through Saturday as 1024 mb high pressure builds into the northern Great Plains & ultimately crosses the open waters. East-northeast winds will steadily increase Saturday night through Sunday as a second area of 994 mb low pressure forms in the central Great Plains. The low will progress over or just south of the southern Lake Michigan Sunday night as it deepens toward 986 mb, resulting in a northerly wind shift. Winds will shift out of the northwest Monday as the low continues into Ontario. Expect another prolonged period of gale, if not storm force gusts across all of the open waters as the low approaches & shifts east of Lake Michigan early Sunday morning through Monday, with headlines becoming necessary within the next 12-24 hours. Prolonged snow is expected Saturday night through Monday, some of which could be heavy. Sleet or freezing rain could mix in with snow over southern Lake Michigan Saturday night into Sunday. Freezing spray potential will increase Monday behind the departing low, with areas of moderate to heavy freezing spray possible. Trends will be monitored in coming forecasts for potential headlines.

Storm force gusts are expected in nearshore zones tonight through Friday. A Storm Warning has thus replaced the previous Gale Warning in all nearshore zones between 10 PM this evening and 10 PM Friday evening. Gusts may decrease below storm thresholds prior to the current 10 PM CDT Friday Storm Warning expiration, with any early cancellations being handled as winds decrease Friday evening. Another prolonged period of gale or storm-force gusts is expected Sunday morning through Monday as a second area of low pressure moves through the western Great Lakes. Expect that headlines will become necessary over the next 12-24 hours. Areas of moderate to potentially heavy freezing spray are possible Monday afternoon.

Quigley

MKX WATCHES/WARNINGS/ADVISORIES

WI...High Wind Warning...WIZ046-WIZ047-WIZ051-WIZ052-WIZ056-WIZ057- WIZ058-WIZ059-WIZ060-WIZ062-WIZ063-WIZ064-WIZ065-WIZ066- WIZ067-WIZ068-WIZ069-WIZ070-WIZ071-WIZ072...4 AM Friday to 4 PM Friday.

Winter Storm Watch...WIZ046-WIZ047-WIZ051-WIZ052-WIZ056-WIZ057- WIZ058-WIZ059-WIZ060-WIZ062-WIZ063-WIZ064-WIZ065-WIZ066- WIZ067-WIZ068-WIZ069-WIZ070-WIZ071-WIZ072...7 PM Saturday to 4 PM Monday.

LM...Storm Warning...LMZ080-LMZ643-LMZ644-LMZ645-LMZ646-LMZ669- LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ870-LMZ872-LMZ874- LMZ876-LMZ878...10 PM Thursday to 10 PM Friday.

Gale Warning...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ868...10 PM Thursday to 10 PM Friday.