NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 081149
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
649 AM CDT Sat Aug 8 2026

.KEY MESSAGES...

- Dry and pleasant today with highs in the low 80s.

- Thunderstorm chances return Sunday. There is the potential for
  a late morning to afternoon round, and then an evening round.
  Strong to severe storms will be possible. Uncertainty remains
  regarding exact timing of the rounds and positioning, however.

- Any storms on Sunday will be capable of heavy rain. Localized
  flooding will be possible, especially where storms repeatedly
  track through the day.

- Multiple rounds of rain and thunderstorms are possible
  through the work week.

&&

.UPDATE...
Issued 618 AM CDT Sat Aug 8 2026

Storm timing appears a bit more delayed Sunday with the 06z run
of the CAMs. The today and tonight period looks mostly dry.
Depending upon your choice of model, scattered showers and
storms may begin in our western CWA as early as 8am on Sunday or
as late as 1pm Sunday afternoon. Given the presence of the LLJ
over Iowa and the MS valley early Sunday, an 8am arrival for
storms makes more sense as storms initiate to our
north/northwest and then track into our CWA. Model trends will
be monitored today for better agreement.

CMiller

&&

.SHORT TERM...
Issued 114 AM CDT Fri Aug 7 2026

Tonight through Sunday night:

With the cold front passing through Wisconsin early this
morning, a few stray showers could still be possible along the
WI/IL border where a mid level moisture gradient and some mid
level FGEN remains. Otherwise largely quiet weather today. As
could clear behind the cold front, there will be a chance for
some fog to develop, mainly for low lying areas and river valley
west of Madison. Any fog that does develop will dissipate
shortly after sunrise.

Late tonight into Sunday morning, a shortwave trough will move
through the Great Lakes Region as zonal flow sets in. The timing
of the shortwave is expected to coincide with the LLJ noising
into southern Wisconsin. The LLJ and the passage of a warm front
will bring some strong WAA to the area. Any instability in the
area while the LLJ moves through the WAA kicks off could bring
some stronger storms to southern Wisconsin. Timing will be the
name of the game here on the instability front. There is a bit
of uncertainty on when the storms develop to our west and move
in which will come into move focus later today. But there could
be a few strong to severe storms (wind and hail the main
threats) if there is decent instability. Shear is expected to be
around 40 kts or slightly better during this time.

Strong to severe storm chances will linger through the day
Sunday. As the forcing shifts east with the strong WAA and
frontal boundary, will the environment remain favorable to
produce severe storms becomes the main question. Guidance
continues to favor the warm front lingering across the state
which should keep conditions favorable for at least a portion of
southern Wisconsin if not all of it. With the strong shear and
good moisture profiles (high PWATs as well), there will be a
concern for heavy rain and flooding should this pan out. Light
and variable corfidi vectors favor the back building and
training of storms which could be a problem more than the severe
potential. The one thing in our favor is the uncertainty in
location which will be dependent on the warm front location. if
the front is more progressive than models anticipate this could
be an issue for another state to the east.

Patterson

&&

.LONG TERM...
Issued 114 AM CDT Fri Aug 7 2026

Monday through Thursday:

With zonal flow aloft into late in the week, there will be
multiple shortwave troughs moving through the flow. This will
provide many opportunities for rain and thunderstorms to develop
across the Great Lakes Region. Mid level moisture will be
persistent across Wisconsin with PWAT values around 1.5 to 2
inches for the first half of the week (roughly through Tuesday).
Heavy rain will be possible and with repeated round of storms
there could be some localized issues with flooding. This lines
up with the WPC excessive rainfall outlooks for southern
Wisconsin. Mostly urban and small stream type impacts for any
areas that receive repeated rainfall and training storms is
expected. The strengths of each round of storms will depend
largely on the timing for any diurnal instability or presence
of an LLJ. Overall expecting afternoon/evening rounds of storms
to be stronger than those overnight or in the early mornings.
Now thats a bit of a generalization as persistent cloud cover or
an environment overworked to early in the morning will leave an
afternoon/evening round weak unless WAA can overcome that. The
reason for all the uncertainty is due to the zonal flow. There
are multiple difference scenarios based on the timing of
shortwave troughs. This uncertainty in the strength and timing
of the shortwaves will dictate storm timing and available lift.
While this unsettled pattern lingers through the entire
extended, its not anticipated for everyday to be a complete
washout. Its also possible that if guidance continues to have
major discrepancies that the forecast holds POPs on longer than
it should (even in the short term) just due to the amount of
uncertainties. A real moment to wait until you can see the
whites of its eyes scenario.

Patterson

&&

.AVIATION...
Issued 649 AM CDT Sat Aug 8 2026

Isolated fog and stratus over western and southwest Wisconsin
should mix out through the morning. Widespread VFR is then
expect over the area through today and into tonight. Winds will
be moderate and northwesterly today, becoming light tonight and
southerly by daybreak Sunday.

The TAF period will be mostly dry save for some thunderstorm
chances Sunday morning mainly after 12z. At this time, the
thunderstorm timing/coverage is ill-defined, so have left them
out of the TAF for this issuance.

CMiller

&&

.MARINE...
Issued 114 AM CDT Fri Aug 7 2026

Low pressure over Lake Superior tonight will move east across
the Great Lakes Region toward the New England states. An
associated cold front will move across the lake tonight with
scattered rain and storms possible. West to northwest winds are
expected to develop behind the front early this morning. Wind
then quickly return to southerly by this evening ahead of the
next approaching low pressure system. An unsettle weather patter
will set up over the Upper Great Lakes next week where weak
waves of low pressure will cross the region and produce rounds
of thunderstorms at times.

Patterson

&&

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

$$

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