NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 040902
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
302 AM CST Sun Jan 4 2026

.KEY MESSAGES...

- A wintry mix of snow, sleet, and freezing rain/drizzle will
  impact southern and central Wisconsin this afternoon and
  evening, with increasing chances for freezing drizzle tonight.
  Patchy freezing fog possible Monday morning. Impacts to
  travel Sunday night and Monday morning are looking
  increasingly possible.

- Temperatures moderating Monday through mid to late week.

&&

.SHORT TERM...
Issued 145 AM CST Sun Jan 4 2026

Today through Monday:

High pressure over the region to start the day with largely
clearing skies this morning. However, the high pressure will
quickly get ushered out with low pressure pushing in from the
west associated with an UL shortwave and strong WAA with a
fairly strong LLJ aloft. While forcing looks a plenty the
moisture will be the primary driver of where precip occurs. Most
of the northern half of the CWA will have enough moisture to
bring some precip this afternoon into the evening but we will
gradually lose some of that moisture higher aloft later into the
evening and overnight. Northeast parts of the CWA may maintain
enough low level forcing and moisture to bring lighter precip
through the evening and into the overnight period.

The question then becomes what for of precip will we see and the
answer to that is a bit complicated. Early in this event as it
pushes in it looks like areas north where precip will be most
likely will largely be snow as temps should remain low enough in
the column to keep everything snow. However, further south and
west where chances are lower overall given more dry air
concerns, there will be increased risk for freezing rain/drizzle
and sleet as surface temperatures will be cold but the
significant warming with height will bring temps aloft to above
freezing and that should cause concerns for a true mixed precip
event. Later into the evening on the backside of this event we
will lose moisture in the DGZ and with temps remaining below
freezing this will become a predominantly freezing drizzle
concern overnight where any precip remains. There is some
uncertainty with this as soundings suggest it may be dry enough
to prevent much precip at all overnight but the soundings are
moist enough, with plenty of WAA still in place, that will
cause some concern that models are not quite grasping the true
moisture profile. Thus there will be concern for some freezing
drizzle overnight, lingering longest toward east central WI.
However, it is worth mentioning that our best forcing is with
the LLJ and WAA but that LLJ/WAA isn't ushering in moist air its
ushering in dry air and thus dry air entrainment may
significantly impact the areas of highest forcing. The forcing
is the very thing pushing out the more moist air.

In addition, as things push out overnight the lowest levels will
moisten up according to model soundings and given the moist
advection layer beginning at the surface at the very least a
very low cloud deck is expected early Monday morning. However,
this could very well be a surface cloud deck/fog with concerns
for freezing fog. There is uncertainty with exactly what to
expect from these moisture profiles but there is at least some
elevated concerns for freezing fog playing a role in adding to
slickness on roads from freezing drizzle/rain/sleet/snow from
Sunday night.

Into Monday freezing fog will remain a slight concern through
most of the morning before temperatures warm up enough to
relieve some of the concerns and are able to release some of
that moisture off the surface. Low level clouds are likely to
stick around through Monday, however.

Kuroski

&&

.LONG TERM...
Issued 230 AM CST Sun Jan 4 2026

Monday night through Friday:

A low-amplitude mid level shortwave trough will cross central MN
and WI Monday night and Tuesday morning. The associated weak
surface low will also cross this area, and light precipitation is
looking more likely with this system. However, the majority of
the precip will be on the north side of that surface low and 850mb
front, more toward central WI, thanks to the location of the left
exit region of the upper jet.

With a solid moist layer from the surface up to 10 kft and
surface temps at or above freezing, this will primarily be a rain
event. However, temps may hover between 30 and 32 degrees for an
hour or two over central WI as the rain moves in, so we have a
chance of freezing rain in the forecast for now. We will be able
to resolve the hourly temps better as we get closer in order to
determine the precip type. The GFS is the only model showing the
925 temps below freezing at this time, with other models a degree
or two warmer. Synoptically, this is a warm advection precip
event, but there are several areas of precip painted in by the
models due to the disjointed shortwave trough. Rain chances will
taper off Tuesday afternoon, but there is a chance that the
surface low could strengthen as it gets into Michigan Tue
afternoon/evening. If that happens, then precip chances could
linger over southeast WI into Tue evening.

Ridging and low level warm air advection will allow for above
normal temperatures on Wednesday. If clouds can clear, highs near
the IL border could be in the mid 40s. Upper 30s are expected
toward central WI.

The extended forecast from Thursday onward continues to be very
uncertain. Models are flip flopping all over and producing surface
lows in varying locations across the U.S. with each run. Overall,
an upper trough will develop over the west half of the country,
with a northern-stream and southern-stream. As usual with the
models, the varying solutions come down to the phasing or not-
phasing of these two upper troughs. This will determine if the
precip associated with the resultant low hits southern WI or
misses it.

Cronce

&&

.AVIATION...
Issued 300 AM CST Sun Jan 4 2026

Lingering MVFR/VFR CIGS over far southern WI this morning that
are gradually clearing from the north that should fully clear
over the next few hours leaving clear skies through the
morning. Some patchy freezing fog possible early this morning in
areas with cleared skies tonight.

Into the late afternoon, another system pushes in bringing
concerns for a freezing rain/drizzle, sleet, and snow mix across
southern WI. Further north snow is more likely with mixiness
further south and west. As the main swath of precip pushes
through the chances for freezing drizzle on the backside of this
system will increase later into the evening and overnight with
lingering freezing drizzle chances through much of the night.
Freezing fog late tonight into Monday morning will be possible
but uncertainty in the density of any fog, however patchy fog
at least with some temporary reduced VSBYS. CIGS may remain VFR
through earlier parts of this event but right now we do not
believe models are capturing the full extent of moisture and
thus MVFR/IFR CIGS are expected overnight for much of the
southern WI with chances for LIFR/VLIFR CIGS into early Monday
morning with high moisture near the surface/fog. Low CIGS may
continue through the day Monday, but there remains uncertainty
in exactly how this situation will unfold with CIGS and VSBYS
tonight into Monday as some models suggest little to no impacts
from VSBYS or CIGS the entire period.

Kuroski

&&

.MARINE...
Issued 300 AM CST Sun Jan 4 2026

West winds will remain variable early this morning as a broad
area of high pressure moves across the western Great Lakes.
Southerly winds will develop by this afternoon as that high
becomes centered over central Ohio, and low pressure moves
across southern Minnesota. Gales are not expected, but winds
over the open waters could approach 30 knots before weakening
Monday morning. Small Craft Advisory has been issued for winds
and waves this evening through tonight.

A few other systems may impact the Lake Michigan area through
mid to late week with winds varying between westerly and
southerly, but the probability of gales is low at this time.
Small Craft may again be needed toward next weekend.

Kuroski

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646...8 PM
     Sunday to 6 AM Monday.

&&

$$

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