textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Light accumulating snowfall will occur tonight into Wednesday morning. Around 1 inch of snow is forecast, possibly up to 2 inches southwest of Madison. A few hours of freezing drizzle is possible as the snow exits.

- 50 percent chance for light rain Wednesday night but could linger into Thursday morning. A very brief period of freezing rain will be possible over east central WI late Wednesday night.

- A warming trend is expected from Wednesday into Saturday.

UPDATE

Issued 639 PM CDT Tue Mar 17 2026

WAA is slow to start up behind the exiting high pressure system and incoming shortwave this evening. Sfc dewpoint depressions are fairly large this evening around 15 to 20 degrees. Which will impact the start time of snow this evening. Thus the low reflectivities across western Wisconsin are likely not making it to the ground yet and may not for another couple hours or until we start to see some of the 30 to 40 dbz returns. Confidence remains high on getting some light snow overnight and the mid level WAA remaining through the overnight. As this warm nose of air moves in aloft early Wednesday morning, there is a concern for a couple hour window for snow to become freezing drizzle as we loose cloud ice.

Patterson

SHORT TERM

Issued 206 PM CDT Tue Mar 17 2026

Tonight through Thursday:

The sfc ridge over srn WI will shift ewd this evening with the onset of sly winds and warm advection expected. In nwly flow aloft, a vorticity maximum over MN will track across the area, while a tight 700 mb baroclinic zone moves ewd across srn WI. 850 mb warm advection will also ensue but mostly push through the area on Wed. Dry air in place will initially limit snow onset, but it will spread west to east from 02Z-06Z. 4-5 hours of light snow is expected followed by a few hours of freezing drizzle as dry air invades the mid levels. Initially a very deep dendrite zone is expected but the entire layer will quickly warm toward -10C with snow changing to areas of freezing drizzle. Overall the fcst soundings suggest only weak lift, strongest over sw WI. Around 1 inch of snow is forecast, possibly two southwest of Madison.

Air temps will then warm above freezing for Wed afternoon on swly winds, but sunshine is very uncertain with lingering stratus probable. Another shortwave trough will approach from the nw late Wed nt and pass early Thu. The models are differing with the amplification of this wave and how widespread the rain showers will be. Went 50-60 percent for rain late Wed nt, possibly lingering into Thu AM.

Gehring

LONG TERM

Issued 206 PM CDT Tue Mar 17 2026

Thursday night through Tuesday:

The extended models agree on a shortwave trough tracking across the nrn Great Lakes Thu nt-Fri, accompanied by a wave of low pressure and weak cold front. Any precipitation is expected to remain to the north.

A well develop low pressure area will then track ewd across Ontario into Quebec for Fri nt-Sat. Swly winds and warm advection will boost high temps into the 60s on Sat west of the MKE metro. A cold front of some degree is then expected to pass Sat nt-Sun, followed by an area of high pressure across the Great Lakes into Mon. Thus temps will cool back down to normal for the early portion of the week.

Gehring

AVIATION

Issued 639 PM CDT Tue Mar 17 2026

VFR to IFR conditions are expected through the period. Snow will be slow to start here across southern Wisconsin as dry air erodes away at the precipitation. Virga will be more likely to start out ahead of any sfc snow. As light snow starts to make it to the ground tonight, visibilities could fall to around 1-2 SM. Snow is expected to be a light powdery snow. Ceilings are expected to fall around 2-4 kft overnight as the snow moves through. Early Wednesday morning (roughly 2 to 8 AM) as the snow is starting to move east out of the state, there is a chance that snow turns to freezing drizzle. This window for freezing drizzle will be small around an hr maybe two for any given location. Should freezing drizzle occur only a glaze of ice is expected. Snow totals As snow and freezing drizzle move out shortly after sunrise, the MVFR ceilings will persist through the rest of the Wednesday morning. The cloud deck will rise to VFR and become scattered Wednesday afternoon. A few areas may see clear skies for an hour or two before more high level clouds return.

Southwest winds this evening will become due southerly tonight and may be breezy at times. Light southwest to south winds are expected Wednesday afternoon through Wednesday night.

Patterson

MARINE

Issued 206 PM CDT Tue Mar 17 2026

Light to modest northwest winds will shift to southwest by late today, as high pressure around 30.2 inches moves across Lake Michigan this evening. Modest to breezy southwest winds will prevail tonight into Wednesday night as low pressure of 29.7 inches progresses through the southern Canadian Prairies into Ontario. A weak cold front will then slowly pass Thursday into Thursday evening with light and variable winds.

Small Craft Advisory conditions are possible Wednesday morning north of Port Washington for persistent south to southwest winds and building waves.

Gehring

MKX WATCHES/WARNINGS/ADVISORIES

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