NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 151950
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
250 PM CDT Wed Jul 15 2026

.KEY MESSAGES...

- Heat Advisory continues this afternoon, but temps will not be
  as hot for the end of the week.

- Isolated to scattered shower and thunderstorm chances along
 and west of I-90 corridor Thursday afternoon.

- WI DNR issued air quality alert for all southern WI through
  Thursday for unhealthy to very unhealthy conditions.

- Wildfire smoke from across northern MN and northwestern
  Ontario is pushing southward into east central WI this evening
  and continue through Thursday contributing to unhealthy air
  quality as well as limiting temps by a few degrees, especially
  toward the lakeshore.

- Shower and storm chances gradually increase for the end of
  the week into the weekend along with closer to normal temps.

&&

.SHORT TERM...
Issued 245 PM CDT Wed Jul 15 2026

Tonight through Thursday night:

As the Heat Advisory is lifted from the CWA tonight,
temperatures are expected to begin to trend slightly cooler.
Overnight, low temperatures are expected to drop to the low 70s
and potentially the high 60s near the lakeshore as a backdoor
cold front stalls across the CWA. Dewpoint temperatures will be
in the low 60s near the lakeshore and high 60s inland, extending
the humid conditions. Upper- level northwesterly flow along the
jet stream creates a high potential for wildfire smoke from
Canada and northern Minnesota to advect into Wisconsin, mainly
impacting areas along and east of I-90 corridor bringing a
reduction in visibility at times tonight through Thursday.

The persistent hot and humid airmass, especially for
southwestern WI Thursday will keep temperatures in the upper 80s
to around 90F across the region, but the stalling of a backdoor
cold front and the presence of wildfire smoke may decrease the
predicted high temperatures. This front also invites the
potential for isolated to scattered showers and storms across
the CWA, but the upper-level ridging and smoke may inhibit
convection and lower precipitation chances (currently 20-30%).
If any thunderstorms do develop, expect them to be brief and
pulsey in nature given the lack of shear. Nevertheless still
will be capable of producing gusty winds as they collapse.
Otherwise expect poor air quality and decreased visibility to
continue on Thursday, and potentially into Friday morning due to
smoke at the surface.

Zawlocki/Wagner

&&

.LONG TERM...
Issued 245 PM CDT Wed Jul 15 2026

Friday through Wednesday:

Main story of the extended will be the gradually cooler temps
into next week along with periodic shower and thunderstorm
chances.

Expect temps to gradually cool through the weekend. Friday and
Saturday are still looking at above normal temps with highs in
the upper 80s to lower 90s along with dewpoints in the upper 60s
to lower 70s. However, not looking as hot as the start of the
week as the upper-level ridge begins to flatten with a series of
mid-level shortwave troughs traversing the region, which will
bring along with it increased daily shower and storm chances.
Friday will be the first of these waves as mid-level vorticity
treks through as the stalled boundary lifts northward as warm
front ahead of a developing surface low in the Plains. This will
place southern WI in the warm sector, but not much in the way
of forcing to concentrate development. Nevertheless with the
increasing PWATs and building instability still could see
scattered shower and thunderstorm development. More likely
pulse type convection if anything develops on Friday. Better
forcing arrives Saturday as the surface low pushes over the
Upper Great Lakes dragging a cold front through the area.
However, the latest guidance has the boundary sliding south
through the morning and departing by the early afternoon. While
forcing and moisture better align with a second mid-level
shortwave trough arrival, the timing may not be conducive to
build up enough instability for stronger storm development
unless this system slows down in the next few model runs and/or
remnant upstream convection/ remnant MCS moves into the area
focusing redevelopment. Nevertheless, will see additional round
of shower and thunderstorm chances for Saturday.

Once the cold front swings through the area on Saturday, it
looks to usher in a cooler Canadian airmass with surface high
pressure for Sunday. Looking at cooler temps with daytime highs
in the low to mid 80s. Southerly flow along with a brief warm up
and higher dewpoints return for the start of next week. Then
expecting another mid-level trough to develop and traverse the
Upper Great Lakes region later Monday into Tuesday. GFS and
ECMWF both prog a deepening surface low across Ontario and
dragging a cold front down across our neck of the woods. Again
this will be the focus for another window for increase PoP
chances. Given the better upper-level jet placement along with
increased deep layer shear and instability, could not rule out
seeing a some scattered stronger storm activity later Monday
into Tuesday. Still plenty of time, for things to shift, but
worth keeping an eye on given the more favorable upper-level
setup at this time.

Otherwise, behind the early week system expect a stronger push
of Canadian air to advect in toward the middle of next week and
given the 6-10 day trends, there is even a potential to see near
to below normal temps.

Wagner

&&

.AVIATION...
Issued 245 PM CDT Wed Jul 15 2026

Seeing a boundary/backdoor cold front off of Lake Michigan
pushing inland this afternoon and expecting it to stall either
along or just east of I-90 corridor tonight. Terminals to the
east will see lighter easterly winds with wildfire smoke pushing
in from the northern MN/western Ontario. SBM is expected to see
drops in visibility from this later this afternoon into the
evening evening dropping in MVFR levels. MKE, UES, and ENW may
also experience the surface smoke this evening and overnight,
but tough to tell exactly how low visibilities will drop with it
further south, but nonetheless could see reductions into
Thursday. Meanwhile depending on where this backdoor cold front
boundary stalls, it may limit the surface smoke from pushing to
far west into MSN and JVL area, but cannot completely rule it
out. On the west side of this stalled boundary will still be the
higher humidity and light winds, so potential for fog
development again tonight will be possible with MSN and JVL into
early Thursday morning with visibilities reaching into MVFR to
IFR possible. Otherwise, smoke and visibility restrictions are
expected to continue for the eastern terminals as the boundary
remains stalled across southern WI for Thursday dissecting the
warm and moisture air tot he west and the not as warm and smoky
air to the east. May see isolated to scattered shower and storm
develop along and west of the stall boundary for thursday
afternoon, which could bring pulse type thunderstorms and gusty
winds through the evening, especially for MSN and JVL.

Wagner

&&

.MARINE...
Issued 245 PM CDT Wed Jul 15 2026

High pressure gradually breaks down this evening as a weak area
of low pressure works its way across Lake Superior and down
Lake Michigan. This has brought a northeasterly wind shift
across the Lake and will continue Thursday. Additional seeing
wildfire smoke from northern MN and northwestern Ontario
reducing visibility across the northern third of the open waters
to 1 nm or less at times this afternoon and likely to continue
into Thursday. Thus a Marine Dense Smoke Advisory has been
issued. Smoke is expected to continue to spread southward, but
uncertain on how low visibilities will fall for the southern
portions of Lake Michigan. Will continue to monitor if an
expansion of the advisory will be needed.

Otherwise, lighter winds expected again on Thursday as another
high pressure briefly builds back into the region before
influence from a low pressure developing over the northern
Plains pushes eastward through the weekend bringing more
southwesterly flow for Friday into Saturday. Then as the low
tracking northeastward, it will drag a cold front across the
Lake resulting in northerly wind shift through the day Saturday
with another high pressure building over the region for Sunday.
Additionally will see periodic shower and thunderstorm chances
across the lake for the end of the week through the weekend.

Wagner

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Heat Advisory...WIZ046-WIZ047-WIZ051-WIZ052-WIZ056-WIZ057-
     WIZ058-WIZ059-WIZ060-WIZ062-WIZ063-WIZ064-WIZ065-WIZ066-
     WIZ067-WIZ068-WIZ069-WIZ070-WIZ071-WIZ072 until 8 PM
     Wednesday.

LM...None.
&&

$$

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