NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 190951
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
451 AM CDT Thu Mar 19 2026

.KEY MESSAGES...

- Gradual warming trend expected through the Saturday.

&&

.UPDATE...
Issued 455 AM CDT Thu Mar 19 2026

The last of the light rain showers are diminishing early this
morning as subsidence from the incoming high becomes more
prevalent. Might see some patchy fog develop through daybreak
out west. Otherwise light and variable winds, drier conditions,
and milder temps in the 40s to low 50s are expected across
southern WI today. Will continue to see the snow pack diminish
with these milder temps as well.

Wagner

&&

.SHORT TERM...
Issued 1120 PM CDT Wed Mar 18 2026

Rest Of Tonight through Saturday:

Synopsis/Mesoanalysis: A weak disturbance is in moving into
northeast and east-central Wisconsin late this evening, encouraging
a scattering of radar echoes from southern Lake Michigan northwest
into central Wisconsin. The passing disturbance will encourage
additional light precip development primarily north of I-94 through
the predawn hours, with surface temperatures supportive for some
freezing rain and drizzle. A light glaze of ice is possible in areas
experiencing freezing rain/drizzle, particularly on elevated and
untreated surfaces. Budget a few extra minutes of travel time if
taking to the roads north of I-94 through sunrise. Northwesterly
upper level flow will continue to influence weather conditions
across the region through the conclusion of the period, with
embedded disturbances encouraging areas of low pressure development
& frontal passages at the surface. A disturbance & surface low will
progress across northern Lake Michigan Thursday night into Friday,
with a cold front crossing southern Wisconsin on Friday morning.
Broad low pressure will build over the Northern Plains on Saturday,
with southwesterly winds allowing for mild high temperatures.

Rest Of Tonight into Thursday Morning: Will be monitoring for
additional areas of light precip through daybreak. Evidenced by 00Z
mesoscale guidance & mid-late evening radar trends, it continues to
appear that the best chances for precipitation will remain to the
north of I-94 through the remainder of the overnight period.
Forecast soundings do hint at brief periods of saturation between ~2-
7 AM further southwest/into the I-94 Corridor, however, so have
maintained slight (~10-20%) precip probabilities as far south as
Madison & the southeast Wisconsin metro areas. Temperatures have
hovered just above freezing in many spots through this evening, but
do anticipate that there will be areas of sub-freezing temperatures
materializing through daybreak. Thus will be watching for freezing
rain/drizzle in areas that do dip below the freezing mark, with
rain/drizzle prevailing in warmer locations. Can't rule out a light
glaze of ice in locations seeing freezing rain/drizzle, especially
on elevated and untreated surfaces. Precip will push southeast of
the area between ~4-7 AM. Some patchy fog is possible during the
morning commute. Don't expect dense fog at this time, but will
nevertheless be monitoring trends.

Thursday Night: The next disturbance will be passing to the
northeast of the area, bringing widespread precipitation to
northeast Wisconsin and the Upper Peninsula of Michigan. Currently
expect conditions to remain dry in southern Wisconsin, but will need
to watch precip trends over the northeastern CWA. Should the
responsible disturbance trend slightly southwest of its current
track, precip probs may become necessary in later forecasts.
Conditions would be mild enough for all rain in the event precip
snuck into the far northeast.

Saturday: Continue to expect the mildest day of the entire forecast
period as south-southwest winds pull warm air in from the Central
Plains. Have maintained NBM temperature forecasts in the evening
update, with the understanding that values may trend cooler closer
to Lake Michigan given a likely lake breeze during the afternoon
hours. While it's expected to stay out of southern Wisconsin through
the afternoon hours, progression trends regarding a cold front
lingering just north of the region will also need to be watched. If
the front's arrival were to speed up, temperatures would trend
cooler from the current forecast areawide.

Quigley

&&

.LONG TERM...
Issued 1120 PM CDT Wed Mar 18 2026

Saturday night through Tuesday:

West northwest flow at 500 mb Saturday night will give way to a
broad trough shifting through the region later Sunday into Sunday
night. The main differential CVA from this looks to remain to the
north of the area. Ensembles suggest a stationary boundary ahead
of a surface low should gradually shift south of the area later
Saturday night into Sunday, with the surface low following the
frontal boundary.

There may be some surface to 850 mb and 850 mb to 700 mb
frontogenesis response that shifts south through the area during
this period, which may combine with some deep moisture to bring
some chances (around 20 to 30 percent, highest north and northeast
parts of the area) for light rain, with some light rain and light
snow mix possible in northern portions of the area.

The precipitation chances will depend on the low track and
available moisture to work with. Ensemble mean probability of 0.01
inches of precipitation are highest toward northern and
northeastern parts of the area, lower to the southwest. North
winds on the backside of the low bring cold air advection into the
area Sunday and Sunday night, with drier conditions returning.

Ensembles then bring high pressure across the region Monday into
Monday night, with dry conditions and seasonable temperatures.
More uncertainty exists with the next frontal boundary that may
shift south through the area Tuesday, as moisture may be lacking.
May keep forecast dry for now.

Wood

&&

.AVIATION...
Issued 455 AM CDT Thu Mar 19 2026

The last of the light rain showers are diminishing this morning.
May still see some patchy fog develop for MSN and JVL through
daybreak. Otherwise with high pressure working its way across
the region today will see VFR conditions prevail with light and
variable winds through this afternoon. May see some scattered
lower ceilings try to spread into southern WI tonight into
Friday morning along with more southwesterly winds as low
pressure and cold front pushes through the area.

Wagner

&&

.MARINE...
Issued 1120 PM CDT Wed Mar 18 2026

1010 mb low pressure is positioned over Ontario late this evening,
resulting in generally southwest winds across the open waters of
Lake Michigan. Said low will advance toward the southern Hudson Bay
through daybreak as 1018 mb high pressure builds into Wisconsin from
the northern Great Plains. Thus anticipate that the current
southwest winds will trend light and variable by daybreak, with
variable winds continuing through Thursday morning. Some light rain
is possible over the southern half of the open waters through
sunrise. A new area of 1006 mb low pressure is forecast to develop
in the Canadian Great Plains Thursday afternoon, allowing winds to
turn east-southeasterly across Lake Michigan. Winds will veer south
to southwesterly across the waters Thursday night as the surface low
progresses over or just north of the northern half of Lake Michigan.
Some rain or snow is possible over northern Lake Michigan during the
low's passage, with wind gusts expected to remain below gale
thresholds. Winds will turn west-northwesterly on Friday as a cold
front moves across the waters.

Winds will become light Friday night through Saturday morning as
1016 mb high pressure moves across Lake Michigan. Increasing
southerly winds are expected Saturday afternoon as a cold front
approaches from the north. The front is expected to cross Lake
Michigan Saturday night into Sunday morning, bringing gusty
northerly winds into Monday morning. Rain and snow showers will
accompany the passing cold front. Widespread gales are not
anticipated at this time, though trends will be monitored over
coming forecasts. Winds will decrease Monday night, ultimately
turning southerly and increasing once again during the day on
Tuesday.

Winds and waves will approach Small Craft Advisory levels in
nearshore zones Saturday night through Monday morning as a cold
front works across Lake Michigan. While not currently expected to be
widespread, a few gusts approaching gale force are possible during
the day Sunday. Expect that headlines will become necessary as this
portion of the period draws closer. Following a brief lull in wind
gusts Monday evening & night, readings will increase and potentially
approach advisory levels during the day Tuesday, particularly in
northern nearshore zones.

Quigley

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...None.
&&

$$

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