NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 062318
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
618 PM CDT Thu Aug 6 2026

.KEY MESSAGES...

- Areas of fog are possible tonight, mainly from Madison to
  Janesville and west.

- A decaying area of thunderstorms may make it into southern
  Wisconsin Friday night.

- Another round or two of storms may roll through southern WI
  late Saturday night and/or Sunday night into Monday.

&&

.UPDATE...
Issued 618 PM CDT Thu Aug 6 2026

The fair weather clouds this evening will slowly diminish as the
sun begins to set leading to clear skies tonight. Dewpoints are
expected to remain in the low to mid 60s overnight and
temperatures are expected to fall into the mid 60s. The clear
skies light winds and saturated low levels should lead to patchy
fog and low stratus tonight. No major changes to the forecast
this evening.

Patterson

&&

.SHORT TERM...
Issued 343 PM CDT Thu Aug 6 2026

Tonight through Friday night:

With clear skies and light winds tonight, fog is looking likely,
especially for areas from Green Lake County through Rock County
and west. The dewpoints are still in the 60s, indicative of
lingering low level moisture. For areas east of that line,
fog is possible, but stratus (low clouds) is more likely given
the weak low level warm air advection (waa).

The low clouds may hang on through much of Friday morning in
southeast WI due to the waa, but once it mixes out, expect highs
in the lower to mid 80s. With dewpoints in the upper 60s to
around 70, it will feel humid, and heat indices will be a few
degrees higher than our temps (in the upper 80s).

A cluster of thunderstorms is expected to develop in northeast
MN, central MN, or northwest Wisconsin Friday afternoon along
the leading edge of a mid level shortwave and associated surface
trough. This may end up being a disjointed system due to
stronger upper level forcing up north and stronger lower level
forcing down south. The storms may split, with one cluster of
storms rolling through northeast Iowa, southwest WI, and
northern IL and the other cluster tracking across Upper
Michigan. Either way, they will be tracking into an environment
(in southern WI) with some CAPE, minimal shear, and not a lot of
synoptic forcing, thus they will be diminishing. The severe
threat for our area is low, but if anything can hold together
from upstream, then damaging winds is our concern.

Cronce

&&

.LONG TERM...
Issued 343 PM CDT Thu Aug 6 2026

Saturday through Thursday:

We will have light northwest winds Saturday in the wake of the
weak surface frontal passage. Look for clearing skies in the
afternoon and highs around 80. Saturday night or Sunday morning,
depending on how quickly that surface high pressure can exit,
the low level jet will point into Iowa, southern WI, or central
WI, wherever the effective 850mb warm front can set up. The
factor determining this will be where the storm outflow lies
from Friday night's storm complex.

There could be some lingering clouds and precip into Sunday
morning, depending on where the storms track late Sat nt. As
long as storms do not develop late in the morning Sunday like
the GFS suggests,the afternoon and evening look pleasant.
Another storm complex could develop Sunday night into Monday
morning on the nose of the low level jet, but that location is
very uncertain (could be southern WI or northern IL) and will
depend on where storms track early Sunday.

The upper level flow may become lines up just right where weak
ripples in it could trigger storms at times along a stationary
frontal boundary over southern WI. However, this front may
actually end up in northern IL. There is a lot of uncertainty on
timing and location of storms in this unsettled weather pattern
that is setting up for next week.

Cronce

&&

.AVIATION...
Issued 618 PM CDT Thu Aug 6 2026

VFR to IFR conditions are expected through the period. The VFR
conditions this evening are expected to remain until fog and low
stratus develops tonight. Then MVFR to IFR conditions are
expected. Currently the fair weather clouds around 3-6 kft will
diminish leading to clear skies after sunset. Fog and low
stratus should start to develop across southern Wisconsin around
midnight at the earliest. Ceilings are expected to be around 800
to 2,000 feet where low stratus develops. Visibilities are
expected to be around 2-4 SM. If skies remain clear there could
be pockets of visibilities around 1 SM or less. Any fog that
develops should dissipate through the morning hours, while low
stratus is expected to remain into the late morning/early
afternoon before dissipating. Once the low stratus has cleared,
fair weather cumulus should develop again around 3-6 kft for the
rest of the afternoon and evening Friday. Heading into Friday
night low chances (10-25%) for scattered rain and storms
returns.

Light and variable winds through tonight become light
southwesterly winds by mid morning Friday. Winds will turn to
the west to northwest by Friday night.

Patterson

&&

.MARINE...
Issued 343 PM CDT Thu Aug 6 2026

Light southerly winds will develop tonight and increase by Friday
afternoon as the a low pressure trough of 29.8 inches reaches
Lake Superior. Scattered showers and storms are possible Friday
night as the crosses Lake Michigan . West to northwest winds
behind the front early Saturday will quickly return to southerly
by Saturday evening ahead of the next approaching low pressure
system. An unsettled weather pattern 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.

Cronce

&&

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

$$

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