textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Freezing rain and sleet continue in southeast Wisconsin into tonight, with a transition to snow expected within the next few hours. Conditions are quickly becoming slippery. Avoid travel if possible.

- The wintry mix of precipitation will transition to moderate to heavy snowfall from northwest to southeast tonight. Blizzard conditions are forecast late tonight into Monday morning as a band of heavy snow at rates to 1"/hr combined with northerly wind gusts of 40 to 45 MPH lead to visibilities less than 1/4 mile. These conditions are expected to affect the Monday morning commute. - A Storm Warning, a Gale Warning, and a Heavy Freezing Spray Warning are in effect through late Monday night and Tuesday morning across Lake Michigan.

- Light accumulating snowfall may impact the Wednesday morning commute.

UPDATE

Issued 808 PM CDT Sun Mar 15 2026

A band of heavy snowfall rates has developed across the Mississippi Valley this evening, with visibilities between 1/4 mile and whiteout conditions reported as a combination of the heavy snowfall and northerly winds gusting to 40 MPH. As low pressure deepens, occludes, and stalls over Lower Michigan, gusts will increase across southern Wisconsin to 45 MPH and even locally up to 50 MPH as this heavy band progresses into southern Wisconsin. Due to these concerns, expecting blizzard conditions to develop across all of southern Wisconsin late tonight through the Monday morning commute. Still expecting the highest accumulations of 5 to 10 inches along and northwest of a line from Sheboygan to Janesville due to the longer duration of these high rates, but concern for the highest rates and highest gusts during the Monday morning commute across areas southeast of this line has led to the Blizzard Warning being issued for all of southern Wisconsin.

MH

SHORT TERM

Issued 132 PM CDT Sun Mar 15 2026

Tonight through Monday night:

Widespread precipitation will continue this afternoon, as deepening low pressure heads east across northern Illinois. The low has trended a bit farther south and temps at the surface and aloft have wound up colder than anticipated today. This has resulted in higher icing impacts from freezing rain north of I-94, which will continue through the afternoon, lingering into early evening in the northeast. Precip type may hang on as all snow in the far northwest forecast area the rest of today, with mainly rain south of I-94 this afternoon.

Low pressure will continue to deepen as it lifts northeast over southern Lake Michigan this evening. The slowing/lifting of the low will result in a gradual transition from rain and mixed precip to all snow northwest to southeast later this afternoon through early this evening. Increased ice totals a bit south of I-94 for late afternoon and early evening as the freezing rain potential may linger a bit longer than anticipated earlier. The transition line between mixed precip and all snow should clear the far southeast by midnight, with snow then persisting overnight into Monday morning.

Another noteworthy change with this system is that models have trended back upward with with the deformation precip on the backside of the surface low mid evening into Monday morning. There will be plenty of forcing from top to bottom, given upper level divergence, a strong vortmax at 500 mb, and ample mid level frontogenesis. There is a dry slot upstream, but looks likely this could fill in fairly quickly based on the bulk of 12Z mesoscale models. Bumped up forecast precip totals during this period, winding up close to the HREF values, while still a little under some of the higher models such as the 12Z HRRR and GFS runs.

Still expecting strong winds on the back side of the deepening low this evening into Monday, which will cause increasing blowing and drifting snow concerns from northwest to southeast as the snow begins to pile up. Model soundings continue to show gusts to 40-50 mph in the mixed layer overnight into Monday morning, with gradually decreasing winds Monday afternoon into the evening. Kept snow to liquid ratios in the 10-13 to 1 range due to the fact that the strong winds will greatly reduce ratios, despite the falling temps and solid forcing within the dendrite growth zone.

The snow should wind down tomorrow from southwest to northeast late morning into late afternoon. Even with decreasing snowfall rates, the lingering strong winds during the day tomorrow will likely result in continued impacts from blowing and drifting across the forecast area into late afternoon. Will maintain the winter weather headline expiration times of 4 pm CDT tomorrow for now, though could see this get pushed a couple hours later across the northeast forecast area as models have slowed a tad with the exiting of the accumulating snow and lingering blowing/drifting snow concerns. Given the potential light icing farther southeast as well as snow totals inching upward and lingering blowing snow concerns tomorrow, leaning towards expanding the Winter Storm Warning a bit farther eastward.

DDV

LONG TERM

Issued 132 PM CDT Sun Mar 15 2026

Tuesday through Sunday:

A surface ridge is expected to build into the area Tuesday morning as the center of a high pressure system sinks south into the middle Mississippi River Valley. Morning temperatures will be in the low single digits and rise to the teens by noon. With some modestly breezy conditions hanging on in the morning, wind chills will hang out around zero until midday. High temperatures for the day are expected to be in the low 20s, which will be about 20 degrees below normal for this time of the year.

Heading into Tuesday night, a clipper system is expected to move southeast toward the state, primarily driven by a weak 500mb shortwave as well as some 850 to 700mb fgen and WAA. At this time the GFS and ECMWF ensembles favor areas southwest of Madison for at least an inch of snow assuming a 10:1 ratio. The GFS has 1 inch at 50 to 70% probs, while the ECMWF is lower at 30 to 50%. Both hold negligible probs for over 3 inches. Current timing has the snow coming in just after the evening rush southwest of Madison, reducing Tuesday evening travel impacts.

Snow ends Wednesday morning and warm advection will push temperatures to highs near 40 with weak high pressure moving across the state. Wednesday night into Thursday, solutions diverge a bit regarding precipitation potential, as the GFS favors dry conditions into the weekend, while the ECMWF brings a trough and light mixed precip through Wednesday night into Thursday. At this time, the NBM only favors 15% to 20% PoPs given the model disagreement.

Heading into the upcoming weekend, a ridge is expected to build over the plains. We'll begin to warm back to above normal temperatures as warm advection kicks in over the upper Midwest and a baroclinic zone sets up from the central Dakotas to the eastern Corn Belt.

CMiller

AVIATION

Issued 808 PM CDT Sun Mar 15 2026

Ceilings between 1000 and 2000 ft continue through the majority of tonight into Monday, with the main impacts to flight categories from a band of heavy snow expected to spread west to east through southern Wisconsin late tonight through early Monday morning. Visibilities between 1/2 and 1/4 mile are expected within this band, and ceilings may fall to IFR during this time frame as well. Gusty northerly winds are expected throughout tonight into Monday morning, with gusts to 40 kt expected within the snow band as well. Precipitation will gradually taper off from south to north midday to early Monday afternoon, with northwesterly gusts to 35 kt continuing throughout the day Monday and leading to continued blowing snow even after precipitation ends. Ceilings and visibilities are expected to improve to MVFR early Monday afternoon, remaining at MVFR into Monday night before skies clear.

MH

MARINE

Issued 132 PM CDT Sun Mar 15 2026

Low pressure of 29.3 inches will approach the southern end of Lake Michigan this afternoon, and pass over the southern end of the lake by midnight CDT tonight. Currently, northwest gales are ongoing over the northern third of the Lake, while a warm front bisects the lake and causes weaker winds from midlake, southward. A Gale Warning continues over all of the lake at this time.

As the surface low lifts north- northeast into Lower Michigan state, gales are expected to shift southward down the lake as winds become northwesterly over the more of the lake and fetch improves. The strong pressure gradient over the lake will allow for very strong winds gusts over roughly the northern half of the lake and storm force winds are anticipated from this evening into Monday afternoon. A Storm Warning is in effect over the northern half of the lake. Along with the high winds, colder air moving over the lake will support heavy freezing spray over the whole lake Monday Morning into Tuesday, and a Heavy Freezing Spray Warning has been issued for this time frame.

Monday, northwest winds will turn northerly and northwesterly, continuing to support storm force gusts into the afternoon. Winds should drop below storm force criteria late Monday afternoon and remain high end gales into Monday evening. While the Gale Warning drops off of the northern half of the lake Monday night, this segment may need to be extended, as models suggest gales may continue over the northern half of the lake until the pre-dawn hours of Tuesday.

Northwest winds then ease Tuesday morning as the surface low pulls way and surface high pressure of 30.3 inches approaches the lake.

Additionally, visibility will be heavily restricted over the lake as heavy snow moves over northern portions of Lake Michigan today, and then all of the lake tonight into tomorrow morning.

CMiller

MKX WATCHES/WARNINGS/ADVISORIES

WI...Blizzard Warning...WIZ046-WIZ047-WIZ051-WIZ052-WIZ056-WIZ057- WIZ058-WIZ059-WIZ060-WIZ062-WIZ063-WIZ064-WIZ065-WIZ066- WIZ067-WIZ068-WIZ069-WIZ070-WIZ071-WIZ072 until 4 PM Monday.

LM...Gale Warning...LMZ080-LMZ673-LMZ675-LMZ777-LMZ779-LMZ874- LMZ876-LMZ878 until 7 AM Tuesday.

Heavy Freezing Spray Warning...LMZ080-LMZ261-LMZ362-LMZ364- LMZ366-LMZ563-LMZ565-LMZ567-LMZ643-LMZ644-LMZ645-LMZ646- LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-LMZ870- LMZ872-LMZ874-LMZ876-LMZ878...4 AM Monday to 11 AM Tuesday.

Storm Warning...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ868-LMZ870-LMZ872 until 10 PM Monday.

Gale Warning...LMZ643-LMZ644-LMZ645-LMZ646 until 1 AM Tuesday.