NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 180500
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1200 AM CDT Wed Mar 18 2026

.KEY MESSAGES...

- Light accumulating snowfall will occur this 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.

&&

.SHORT TERM...
Issued 12:00 AM CDT Tue Mar 17 2026

Today through Wednesday:

The snow is finally starting to eat away at the dry air this
evening. Snow has started across western and west central
Wisconsin. Virga may still be the winning out in the east but
now that switch has flipped to a saturated low level that too
should progress nice across the entire area. If you haven't seen
snow by now then it should arrive around Midnight or shortly
thereafter. This will be a dry and powdery snow. Rates will be
low and overall accumulations of snow are around 1 inch. Far
southwestern portions of the area could see up to 2 inches and
areas in our northeast could see around a half an inch.

Looking later into the morning, mid level WAA continues to
slowly cause temperatures to rise above zero. Some sounding
models are still trending with this layer losing saturation in
the mid levels but the result is still the same. Whether we lose
saturation aloft or warm above zero, the low levels are still
saturated below freezing and that will result in a loss of cloud
ice. This will give us a small window for freezing drizzle. This
further tracks with whats up stream in on the western edge of
this system in Iowa and Minnesota. The earliest we could see in
this in our west is around 2 AM and that would slowly pull east
until it exits around 8 AM. This will be a very fine
drizzle/mist so not anticipating more than a glaze of ice
possible.

Skies will remain mostly to partly cloudy through the rest of
the day once the snow and freezing drizzle has ended. Clouds
from this system will pull out as those from the next incoming
system for tonight move in. The set up will be very similar with
this next system however, temperatures will be warmer under the
persistent south to southwest winds and WAA. Therefore the
predominate precipitation type will be rain. Light rain showers
should move in late this evening into tonight and persist into
late Thursday morning. Meso models do have two distinct areas of
precipitation which shows the spread well here. One has rain
mostly along and east of Marquette to Dodge to Kenosha Counties
while the other option is more along a line from Sauk to Dane,
to Rock. Everyone should see rain at some point, but there will
be a narrow area that gets 0.1 to 0.2 inches of rain. Kept POPs
broad across the area as this could fluctuate yet on who sees
it, but this will largely be unimpactful. Whats more impactful
is the concern that we get fog as well during this time.
Temperatures will be slightly warmer, snow will be melting and
light and variable. If fog does develop it will likely remain
into Thursday morning or beyond high pressure builds in keeping
winds light and melting snow keeps the low level saturated.

Patterson

&&

.LONG TERM...
Issued 12:00 AM CDT Tue Mar 17 2026

Thursday through Monday:

An upper level ridge will begin to slowly shift east out of the
western CONUS Thursday. As this ridging builds in there are signs
for a shortwave trough to move through the larger flow late Thursday
night into Friday, but guidance is slowly lifting that shortwave
further north. This is keeping the better PVA across northern WI,
Michigan and Canada. Thus chances for precipitation are very low
to near zero across southern Wisconsin. Sheboygan CO is the only
area to get around 10% Friday late morning/afternoon as this
shortwave pulls out to the east. South to southwest winds and
warming temperatures will favor rain should this system pull
slightly south in subsequent runs.

As the shortwave clears the ridge will remain until late Saturday
and Sunday. Guidance is suggesting a stronger trough descending
across the Pacific Northwest and advecting east. This would
flatten out the ridge across the entire Northern Plains and into
the Great Lakes Region for the weekend. While the overall
consciouses of flatting the ridge is flavored, the time that
this occurs and the strength of the trough differs greatly. This
is most easily seen the deterministic guidance, but shows up in
the ensembles and cluster analysis as well. The cluster
analysis is highlight the ridge with a monopole structure
showing the spread in the strength and amplitude over the
trough, but the signal remains on how much this breaks down.
From deterministic guidance, the Euro is the fastest with the
trough favoring a more northern track. While the GFS and CAN are
slower and slightly further south with the 500 mb PVA. This
translates with the low POPs around 10-20% Saturday night
through Sunday. That should be refined as we get closer to the
weekend.

One more exciting feature if your looking forward to warm weather
this spring is that the upper level ridging and low pressure
systems passing to our north will bring WI some WAA. South to
southwest winds will set up Friday and remain largely in place
through Sunday morning. This will bring in some slightly above
normal temperatures. Saturday looks to be the warmest by far, but
there could be further adjustments in how warm it gets. Guidance
tends to struggle with temperatures in the spring and fall.
Wouldn't be surprised to see some slightly colder temperatures if
the snowpack is still lingering around (still warm but maybe not
in the mid to upper 60s like some of the ensemble guidance is
suggesting). Only time will tell. Beyond this weekend, weather is
largely uneventful with high pressure moving through the Great
Lakes Region and a return to normal temperatures.

Patterson

&&

.AVIATION...
Issued 12:00 AM CDT Tue Mar 17 2026

VFR to IFR conditions are expected through the period. snow is
slowly beginning to fall and move east with time now that the
low level dry air is being eroded. Virga may still be falling in
the east and northeast for another hour or so yet, but snow
will be falling across the area by midnight. Visibilities could
fall to around 1-2 SM with the stronger banding. 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
this 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. Should freezing drizzle occur only a glaze of
ice is expected. As snow and freezing drizzle move out shortly
after sunrise, the MVFR ceilings will persist through the rest
of the morning. The cloud deck will rise to VFR and become
scattered later this afternoon. A few areas may see clear skies
for an hour or two before more high level clouds return this
evening ahead of the next approaching system. With warmer
temperatures setting up ahead of this system, rain will start to
move in late this evening into the overnight hours. There is a
chance that some fog could develop as winds weaken and rain
falls on the snow pack.

Southwest winds this evening will become due southerly early
this morning and may be breezy at times. Light southwest to
south winds are expected this afternoon through tonight. There
is a chance that winds become light and variable a few hours
late tonight into early Thursday morning.

Patterson

&&

.MARINE...
Issued 12:00 AM CDT Tue Mar 17 2026

Light to moderate southwest to south winds are expected across
the lake as high pressure around 30.2 inches moves east north east from
southern Illinois toward the southern New England States. a
Modest to breezy southwest winds will prevail into tonight 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.

A Small Craft Advisory is in effect for the nearshore waters
this morning into early this evening due to the breezy south-southwest
winds and building waves.

Patterson

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646...6 AM
     Wednesday to 5 PM Wednesday.

&&

$$

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