NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 170508
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1208 AM CDT Fri Jul 17 2026

.KEY MESSAGES...

- Very warm and humid conditions continue Saturday with heat
  indices in the 90s, but remaining below heat headlines.

- Wildfire smoke from across northern MN and northwestern
  Ontario will continue tonight into Friday contributing to very
  unhealthy/hazardous air quality. Thus WI DNR issued air
  quality alert for all southern WI through noon Friday when
  southwesterly winds help improve conditions briefly before
  returning this weekend.

- Increased shower and storm chances Friday afternoon/evening
  and Saturday and again for the start of next week.



&&

.SHORT TERM...
Issued 1208 AM CDT Fri Jul 17 2026

Tonight through Friday:

Persistent easterly low level flow tonight will keep the smoke
in place into early Friday morning. The latest HRRR near surface
smoke suggests the concentration of smoke may even increase a
bit overnight. By mid-morning tomorrow, winds will become
southwesterly, which should begin to push the near surface smoke
out of the area. By early afternoon, the HRRR shows the smoke
largely clear of southern Wisconsin, except near the lake, as a
winds may be along shore or onshore during the afternoon. There
is uncertainty with whether or not a lake breeze will move
onshore during the afternoon.

An isolated shower or two will continue early tonight, with
mainly dry weather then expected the rest of the night into
Friday morning. Dewpoints will increase tomorrow as southwest
winds prevail, with a bit more heating and instability to to the
decrease in smoke. As a weak shortwave moves through, isolated
showers and storms will be possible in the afternoon and
evening hours. It will be another warm day with high temps
around 90 and heat indices into at least the mid-90s.

DDV

&&

.LONG TERM...
Issued 1208 AM CDT Fri Jul 17 2026

Saturday through Thursday:

A cold front will drop through during the day Saturday and may
bring scattered storms to southern Wisconsin. Latest model
trends keep the higher precip chances south and east, though. It
will be warm and humid again Saturday. With cooler and drier
conditions not expected to arrive until at least the evening
hours. The 00Z HRRR is showing that smoke may return behind the
cold front later Sat into Sunday as northerly winds develop. Dry
weather and near normal temps are then expected Sunday under
high pressure.

Another low and front will bring storm chances on Monday along
with briefly warmer and more humid conditions ahead of the
front. High pressure will follow this system, with near normal
temps and dry weather likely for Tue through Thu.

DDV

&&

.AVIATION...
Issued 1208 AM CDT Fri Jul 17 2026

Isolated showers and storms will remain possible tonight north
of Madison. Otherwise, continued smoke will be the story
through the overnight hours. Outside of the far southwest
forecast area, smoke with visibilities of 1 to 3 miles is likely
to persist into Friday morning. Conditions should improve from
southwest to northeast mid morning into early afternoon under
southwest low level winds. Isolated storms will be possible
again tomorrow afternoon and evening.

DDV

&&

.MARINE...
Issued 1208 AM CDT Fri Jul 17 2026

Wildfire smoke from northern MN and northwestern Ontario
continues across all open waters of Lake Michigan and will
reduce visibility to 1 nm or less at times. Thus a Marine Dense
Smoke Advisory continues today through Friday for all open
waters.

Lighter winds continue tonight as high pressure around 30.1
inches gradually exits the region ahead of an incoming low
pressure around 29.7 inches tracking in from the Northern
Plains. This low pressure will shift winds across Lake Michigan
to the southwest on Friday and continue to push across Ontario
later Friday through Saturday dragging a cold front across the
lake through Saturday morning. Northerly winds will develop
behind this frontal passage through the day Saturday along with
high pressure around 30.0 inches. The high will then work its
way across the Upper Great through the day Sunday and departing
to the east overnight Sunday while another deepening low tracks
across Ontario for the start of next week. Expect more southerly
wind for Monday before another, stronger cold front pushes
through the region by Tuesday.

Additionally will see periodic shower and thunderstorm chances
across the lake heading into the weekend through the start of next
week.

DDV

&&

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

$$

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