NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 050952 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
452 AM CDT Sun Jul 5 2026

.KEY MESSAGES...

- Patchy fog is expected until the middle morning hours, with
  patchy dense fog in low lying areas.

- There are small chances (around 15 to 20 percent) for showers
  and a few thunderstorms in far southeast Wisconsin this
  morning, as well as this afternoon along and west of
  Interstate 90. Isolated cloud-to-ground lightning would be the
  main impact with any activity.

- Otherwise quiet weather and less humid through the beginning
  portions of the week.

- Next opportunity for widespread showers and thunderstorms
  arrives Wednesday into Thursday.

&&

.UPDATE...
Issued 452 AM CDT Sun Jul 5 2026

There remains a good amount of middle to high clouds across the
area early this morning, which may be limiting fog formation to
mainly low lying areas. Will keep patchy fog in the forecast
until the middle morning hours, when northeast winds begin to
pick up. May see patchy dense fog in low lying areas, mainly
toward south central Wisconsin. Not sure the fog will become
more widespread with the clouds in the area, so will watch web
cameras into this morning.

In addition, scattered showers over southern Lake Michigan,
associated with the 500 mb shortwave trough slowly shifting
through the region, may continue to rotate into far southeast
Wisconsin this morning. There may be an isolated thunderstorm
as well in this area. Will adjust precipitation chances upward
accordingly in this area if the showers continue to rotate
toward that area.

Kept 20 percent chances for a shower or thunderstorm this
afternoon mainly along and west of Interstate 90, where mean
layer CAPE may rise above 1000 J/kg with weak deep layer bulk
shear and little to no capping. There are little in the way of
low level boundaries and upward vertical motion, so felt 20
percent chances were enough for now. An isolated cloud-to-
ground lightning strike would be the main hazard with any
storms.

Wood

&&

.SHORT TERM...
Issued 1100 PM CDT Sat Jul 4 2026

Rest of Overnight through Sunday night:

Synopsis/Mesoanalysis: Thundershowers have diminished late this
evening thanks to the loss of daytime heating & easterly
surface flow pulling stable air inland from Lake Michigan. A
diffuse surface pressure gradient is resulting in calm to
light/variable surface winds across the area, with observations
suggesting that decoupling of the boundary layer is in-progress
across southern Wisconsin. With near-surface moisture still
elevated regionally, said decoupling could result in fog
development through the remainder of the overnight hours. Some
dense fog can't be ruled out, with trends being monitored for
possible headlines through tonight. Slow down, use low beam
headlights, and allow for extra following distance if
encountering fog on the roads. To the northwest of the area, a
complex of thunderstorms continues from Eau Claire southwest
toward the Albert Lea, MN vicinity. These storms will continue
to drift south toward the Iowa-Minnesota border near-term,
though stable air will impede any eastward progress into
southern Wisconsin. A few showers are possible west of Madison
Sunday afternoon. Apart from an isolated flash of lightning &
clap of thunder, hazards aren't expected in any showers that
develop Sunday afternoon.

Rest of Overnight: Will be monitoring visibility trends as
areas of fog attempt to fill in across southern Wisconsin. Can't
rule out some areas of locally dense fog given light winds in
place regionally & an inversion above the boundary layer. If
necessary, will address any such areas of dense fog with
appropriate headlines. Can't entirely rule out an isolated
shower in far southeast Wisconsin through daybreak as a remnant
shortwave/MCV from afternoon storms lingers over southern Lake
Michigan. Apart from the HRRR, most high-res guidance points
toward dry conditions in the vicinity of this feature. Have thus
capped precip probabilities below 15%/mentionable thresholds in
the evening forecast, but will be monitoring for possible
adjustments in the event that the HRRR solution verifies.

Quigley

&&

.LONG TERM...
Issued 1100 PM CDT Sat Jul 4 2026

Sunday night through Friday:

A quieter weather pattern will settle over the region early in
the week as a western CONUS ridge builds, with an eastern CONUS
trough. Nestled between these two features, we will experience
northwest flow aloft. Will need to monitor for occasional
passing waves embedded in this northwest flow, but there will be
more dry time than active time next week.

Overall expect dewpoints to lower a bit, trending a bit more
comfortable than the past week. Lows will be in the 60s and
highs in the low/mid 80s. A signal is starting to hone in on
better rain chances later Wednesday into Thursday.

Looking a bit longer term, the GEFS supports keeping this
western ridge/eastern trough pattern into next weekend and
beyond.

Gagan

&&

.AVIATION...
Issued 452 AM CDT Sun Jul 5 2026

There remains a good amount of middle to high clouds across the
area early this morning, which may be limiting fog formation to
mainly low lying areas. Will keep 3 to 5 mile fog prevailing or
a TEMPO group in TAFs for area terminals until the middle
morning hours, when northeast winds begin to pick up. May see
patchy dense fog in low lying areas, mainly toward Madison and
Janesville terminals. Not sure the fog will become more
widespread with the clouds in the area.

In addition, scattered showers over southern Lake Michigan may
continue to rotate into Milwaukee and Kenosha terminals this
morning. There may be an isolated thunderstorm as well in this
area. Otherwise, the middle to high clouds should linger into
the morning and early afternoon, before becoming more scattered
later in the day.

There is a small chance for a shower or thunderstorm this
afternoon mainly along and west of Interstate 90. Left mention
out of Madison and Janesville terminals for now. Modest
northeast winds are anticipated today across the area, with some
gusts to 15 to 20 knots for terminals near the lake.

Winds will become light tonight and remain northeasterly, with
clouds clearing out. There may be patchy fog again later
tonight in low lying areas and in the Wisconsin River Valley.

Wood

&&

.MARINE...
Issued 452 AM CDT Sun Jul 5 2026

High pressure around 30.2 inches northeast of the region will
remain in place through Monday. Weak low pressure around 29.9
inches will slowly move east across Indiana into Ohio during
this time. Scattered showers and a few thunderstorms are
expected over mainly the far southern portions of Lake Michigan
today into early this evening. Increasing north to northeast
winds are expected as well today, lingering tonight into Monday.

Areas of dense fog should linger into the middle morning hours
across central and southern portions of the lake, where a Dense
Fog Advisory is in effect. There is an expectation that the fog
will diminish by the middle morning hours, with increasing north
to northeast winds.

High pressure around 30.0 inches will then shift southeast
across the region Monday night and Tuesday, with lighter winds.
Southwest winds should increase Wednesday, ahead of a cold front
moving toward the region.

Wood

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Dense Fog Advisory...LMZ080-LMZ366-LMZ565-LMZ567-LMZ643-LMZ644-
     LMZ645-LMZ646-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 until 10 AM
     Sunday.

&&

$$

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