NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 261225
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
725 AM CDT Sun Jul 26 2026

.KEY MESSAGES...

- Patchy fog quickly burns off by mid-morning.

- Hot and humid conditions Sunday and Monday are likely. A Heat
  Advisory is in effect from noon to 9 PM CDT Sunday. Additional
  Heat Advisories may be needed Monday.

- Isolated to scattered storms may develop Sunday afternoon and
  evening. Large hail and damaging winds would be possible with
  this activity. Sunday night, a line of storms with damaging
  winds and hail is expected to develop and progress
  southeastward.

- Monday, a cold front will bring final chances for storms to
  southern Wisconsin. All hazards are possible with this
  activity, but confidence in exact timing and placement remains
  dependent on Sunday night storms.

&&

.UPDATE...
Issued 730 AM CDT Sun Jul 26 2026

Concerns regarding early morning storm potential west of I-39
have waned, as overnight activity in the Plains outran the low
level jet on approach to the Mississippi River during the
predawn hours. Lack of precip, light winds, and a very muggy
boundary layer have resulted in pockets of fog development over
the last couple hours. Visibility reductions have remained
manageable on a broad basis, though localized pockets of 1/2 to
1 mile visibilities have periodically been reported. Isolated &
brief nature of these obs, in addition to quick improvements
coming with the rising sun, should preclude the need for any
Special Weather Statements or advisories. Trends will
nevertheless continue to be monitored. Slow down, use low beam
headlights, and allow for extra following distance if
encountering fog on the roads early today.

Heat and humidity remain on track for this afternoon with
sunshine building in from the northwest. Heat Advisory thus
remains on track between noon and 9 PM across the majority of
the area. Still seeing a decent signal for a lake breeze across
east-central Wisconsin, so have continued to hold Sheboygan and
Ozaukee Counties out of the Heat Advisory through the overnight
hours. If the lake breeze were to trend weaker than currently
forecast, consideration would be given to including all of the
county warning area in the Heat Advisory. Will be monitoring
trends. Regardless of whether/not a heat headline is in effect
in your location, be sure to practice proper heat safety if
planning to be outside today. Drink plenty of water, wear
light-colored and loose-fitting clothing, and take cooling
breaks in the shade or air conditioning.

Still anticipating areas of severe storm development regionally
later today. Apparent in current satellite imagery, wake
subsidence affiliated with overnight storms in the Plains is
allowing for clearing skies across most of Minnesota and
Wisconsin. Resultant surface heating & a stout elevated mixed
layer will thus allow instability to build without the
impediments of cloud cover or precipitation through most of
today from southern Wisconsin northwest into the Minnesota
Arrowhead. Storm development then becomes favored by late this
afternoon/this evening, with the main question being the number
of initiation corridors that can be realized regionally.
Majority of the meso guidance suite has settled to a bimodal set
of solutions regarding initiation zones, with one camp favoring
a single area of storm development in the Minnesota Arrowhead &
the other showing dual initiation in the Minnesota Arrowhead
& the Upper Peninsula/northern Wisconsin. Northwest to
southeast alignment of the building instability gradient, in
addition to northwesterly steering flow, would pull any/all of
this development toward southern Wisconsin from the second half
of the evening into the overnight. Thus, which initiation
solution is realized will drive whether southern Wisconsin will
be in play for one or multiple clusters of convection through
the overnight period. If the single corridor solution verifies,
a single cluster of storms would be favored near & after
midnight. If the double corridor solution verifies, multiple
clusters of storms would be favored from the second half of the
evening into the predawn hours. Anticipating further clarity on
this part of the forecast in the upcoming 12Z CAM suite, as well
as in observations from this morning into this afternoon.

Regardless of the number of storm clusters, prevailing
environment will be favorable for severe weather this evening &
tonight. Anticipating that damaging winds will be of greatest
concern, with some potential for a few gusts reaching/exceeding
70 MPH. Will need to monitor for some hail and isolated tornado
potential as well. Stay weather aware into tonight, and have a
way to be woken up if warnings are issued after you head to bed.

Quigley

&&

.SHORT TERM...
Issued 128 AM CDT Sun Jul 26 2026

Today through Monday:

Currently keeping an eye on Minnesota as convection has
blossomed over the central portions of the state. Rapid refresh
CAMs suggest a dying MCS may clip the southwestern portions of
our CWA near daybreak on Sunday. If this were to occur, gusty
winds and hail would be the main hazards.

Subsidence is then expected following this morning convection
and skies should clear. Dew points are expected to rise into
the mid 70s tomorrow, amid daytime highs in the low 90s. This
will lead to heat indices in the 100 to 103 range over much of
the area tomorrow. The weak pressure gradient will promote a
lake breeze which may keep the immediate lakeshore cooler for
tomorrow. A Heat Advisory has been issued for much of southern
WI from Noon to 9PM today.

It looks increasing likely that storms will hold off until
either the evening or overnight hours tonight into Monday. One
constant among the CAMs is that an MCS will fire closer to the
500mb trough over northern WI/UP of Michigan and propagate
south-southeast into central WI. However, CAMs vary regarding
timing/positioning, as some have this complex further east over
Lake Michigan, while others have this MCS tracking south into
our CWA around midnight. In either scenario, it does look like
convection may linger through the night following the main MCS
as the low level jet triggers new storms along an outflow
boundary. With whatever MCS gets going, gusty winds and hail
will be the main threats, as DCAPE will be near 1100 J/kg, mid
level lapse rates will be near 8 C/km, and effective bulk shear
will approach 70 knots. A conditional boundary interaction with
the remnants of the lake breeze may lead to a sneaky QLCS
tornado threat on an isolated basis, provided the boundary
doesn't wash out quickly after dark.

Weak convection then may linger into Monday with some potential
for storms to reinvigorate ahead of a cold front with daytime
heating late Monday. Given the potential for convection and
cloud cover to linger during the day, have held off on hoisting
a Heat Advisory for Monday at this time until details about
Monday's convection become clearer.

CMiller

&&

.LONG TERM...
Issued 105 AM CDT Sun Jul 26 2026

Tuesday through Saturday:

Mid week looks quiet as a sfc high pressure ridge builds into
the upper Great Lakes region. Northeast sfc flow Tuesday and
Wednesday should promote more manageable dew points in the low
60s and daytime highs in the low to mid 80s. Precip chances then
return late week as a warm front lifts northward into the
region and humidity mildly increases.

CMiller

&&

.AVIATION...
Issued 730 AM CDT Sun Jul 26 2026

Mix of VFR, MVFR and IFR flight categories prevails this morning
with areas of low stratus and fog across the region. Given
sporadic spatial nature to reductions, have handled current
conditions/reductions with TEMPO groups through mid-morning at
all terminals. Anticipating returning VFR flight categories by
mid-morning. Monitoring for one or multiple clusters of
thunderstorms into tonight, some of which could be severe. Given
remaining uncertainties regarding the number and placement of
storm clusters, have addressed potential with PROB30 groups in
the 12Z forecast, and will refine with TEMPO/prevailing groups
as forecast confidence increases later today.

Quigley

&&

.MARINE...
Issued 1237 AM CDT Sun Jul 26 2026

No major changes to the going forecast

A weak low pressure trough will stall along the Wisconsin-
Upper Michigan border this evening. It will remain over
Wisconsin and Lake Michigan through most of Monday which will
result in increasing thunderstorm chances with severe storms
possible. Very warm, moist and unstable air flowing over the
relatively cool waters may cause patchy dense fog over the lake
through Monday as well.

Northerly winds will develop Monday night through Wednesday as
high pressure builds over the Upper Great Lakes and the front
pushes southward. A few gale force gusts are possible Tuesday
afternoon. Look for southerly winds and more unsettled weather
to resume Thursday into next weekend.

CMiller

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Heat Advisory...WIZ046-WIZ047-WIZ051-WIZ056-WIZ057-WIZ058-
     WIZ059-WIZ062-WIZ063-WIZ064-WIZ065-WIZ066-WIZ067-WIZ068-
     WIZ069-WIZ070-WIZ071-WIZ072...noon Sunday to 9 PM Sunday.

LM...None.
&&

$$

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