NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 170023 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
723 PM CDT Thu Jul 16 2026

.KEY MESSAGES...

- Isolated to scattered shower and thunderstorm chances along
  and west of I-90 corridor this evening.

- Very warm and muggier 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.

&&

.UPDATE...
Issued 723 PM CDT Thu Jul 16 2026

Isolated showers and storms will remain possible this evening,
mainly southwest of a line from the Wisconsin Dells to
Burlington. Otherwise, continued smoke will be the story
through the rest of the evening and overnight. Outside of the
far southwest forecast area, smoke with visibilities of 1 to 3
miles is likely to persist into Friday morning. No significant
updates to the forecast are anticipated for the remainder of
the night.

DDV

&&

.SHORT TERM...
Issued 235 PM CDT Thu Jul 16 2026

Tonight and Friday:

Smoky conditions and very unhealthy/hazardous air quality
continues, but gradually improves from southwest to northeast
late this afternoon/evening as a warm front lifts and stalls
across southwestern portions of the CWA. This boundary will be
the focus for pulse-type shower and thunderstorm development
this afternoon and evening as hotter, more moisture air results
in higher instability across southwestern corner of the CWA.
This is proving to be enough for scattered showers and storms,
but given the lack of shear, any activity builds and collapses
quickly. Nevertheless still may see a a few storms build tall
enough to produce lightning and gusty winds if they are able to
interact with the boundary along with any outflows from nearby
decaying showers/storms. This activity will continue through
sunset, but diminish with the loss of daytime heating.

Also looking at the this boundary to stall along the I-90
corridor tonight as prevailing easterly flow slows it
progression overnight and will allow for areas to the southwest
clear out from wildfire smoke a bit more compared to areas to
the east where the lower visibility will continue through much
of the night. Expecting smoky conditions to gradually improve
through daybreak Friday as southwesterly winds pick up as the
warm front progresses northward, but will linger longer along
the lakeshore longer than inland areas.

Otherwise, will see temps and dewpoints warm through Friday
afternoon behind the warm front. Given SBCAPE building to
around 1000 J/kg with dewpoints in the upper 60s into lower 70s.
While environment remains conductive for additional
thunderstorm development as depicting by the 12-18z CAMs, tough
to tell what the forcing mechanism will be the focus for
initiation. Nevertheless, the potential remains for
afternoon/evening shower/storm development (20-40%). Again not
expecting strong activity given the lack of shear, but will
monitor.

Wagner

&&

.LONG TERM...
Issued 235 PM CDT Thu Jul 16 2026

Friday night through Thursday:

Focus then shifts to the the upper-level trough progged to dig
down across the Upper Great Lakes Saturday. The associated
surface low will develop and track across northern MN/WI
overnight Friday into Saturday dragging a cold front down
across southern half of WI Saturday morning. This will bring
some shower/storm chances along the frontal passage, but given
the morning timing not expecting strong or widespread coverage.
Chances will diminish through the morning with drier airmass.
However, accompanying the northerly winds shift will also be a
return of wildfire smoke to southern WI Saturday and lingering
into Sunday as high pressure works its way across the region.

While smoke returns for the end of the weekend temps are
looking cooler on Sunday with highs in the low to mid 80s. Then
as the high shifts southeast later Sunday, expect warmer temps
to return for the start of the week ahead of a deepening trough.
This looks to be the strongest of the systems in the extended
period with a sub-1000mb surface low trekking east across
Ontario through the day Monday with a cold front pushing across
the Upper Midwest later Monday. Will see +1000 J/kg of SBCAPE,
better deep layer shear (+50 kt), and more favorable upper-level
jet dynamics align over the region with this frontal passage.
Thus expect increased thunderstorm chances along with potential
for stronger to severe storms if these trends persist.

Behind this early week system, expect a cooler Canadian airmass
to settle into the region through the middle of next week as
high pressure builds. Given the extended trends, there remain
the a potential to see near to below normal temps.

Wagner

&&

.AVIATION...
Issued 723 PM CDT Thu Jul 16 2026

Isolated showers and storms will remain possible this evening,
mainly southwest of a line from the Wisconsin Dells to
Burlington. Otherwise, continued smoke will be the story
through the rest of the evening and overnight. 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 235 PM CDT Thu Jul 16 2026

Wildfire smoke from northern MN and northwestern Ontario has
spread 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 this evening as high pressure gradually
exits the region ahead of an incoming low pressure 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. 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.

Wagner

&&

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

$$

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