NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 210027 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
727 PM CDT Fri Mar 20 2026

.KEY MESSAGES...

- Patchy fog is expected to develop toward central Wisconsin
  tonight, and some dense fog may occur.

- Above average temperatures are expected through the middle of
  next week, with the highest temperatures expected Saturday.
  The warm temperatures may reach all the way to the lakeshore,
  depending on if the gusty southwest winds develop there.

- Next chances (around 15 to 25 percent) for precipitation are
  mainly Saturday night into Sunday. The next better chances
  (around 25 to 40 percent) are likely for next Thursday.

&&

.UPDATE...
Issued 727 PM CDT Fri Mar 20 2026

Patchy fog may develop tonight for areas toward central
Wisconsin, as a possible sharp inversion develops over these
areas that still have a solid snowpack on the ground. Given the
mild airmass over these areas tonight into early Saturday
morning, there may be some fog and low stratus clouds that
develop. Some dense fog may occur, mainly in low lying areas.
The middle to high clouds that are moving through may deter some
of the fog development, so trends will need to be monitored.

The temperature forecast for Saturday will be tough, as there is
uncertainty with how far east the gusty southwest winds develop
in the afternoon. If they make it to the lakeshore areas by
middle afternoon, then highs into the 70s may occur over most of
the area. Onshore winds from the south southeast may linger
until early to middle afternoon, so the wind shift may warm up
temperatures quite a bit in a short amount of time. Will
continue to look at the latest models and determine if highs and
winds need adjustment for Saturday closer to the lakeshore.

Wood

&&

.SHORT TERM...
Issued 200 PM CDT Fri Mar 20 2026

Tonight through Saturday night:

Late tonight there will potential for patchy fog that may become
dense toward central WI as moisture from snow may be trapped
under a fairly significant inversion layer. Fog from this may
bleed into parts of southern WI. Fog should quickly dissipate as
the sun rises.

Quiet conditions in the short term expected as large scale
ridging in the southwest US keeps our region warm and dry with
any system pushing through well to the north of the CWA. Highs
Saturday will be on the warm side with a chance for mid 70s in
parts of southwest WI. Otherwise at the surface, low pressure
swings through the central Great Lakes today with weak high
pressure developing into the region tonight while another low
pressure system swings into WI Saturday bringing southerly flow
back to southern WI, which will aid in the warm temperature
trends for Saturday. The low will swing through overnight but we
will likely remain on the dry side of the low at least through
Saturday night.

Kuroski

&&

.LONG TERM...
Issued 200 PM CDT Fri Mar 20 2026

Sunday through Friday:

Quite a bit of uncertainty with this Sunday system particularly
as it relates to low to midlevel moisture. With the low pressure
system coming through precip chances seem fairly high across
northern WI but chances further south across southern WI are more
dicey. This is primarily due to less upper level forcing in a
zonal flow regime in combination with limited 700mb moisture and
questionable low level moisture. On the other hand fairly
substantial midlevel Fgen and WAA will bring increased forcing in
the low to mid levels. This looks like the precip potential for
this event will come down in large part to midlevel moisture and
whether the 700mb band of moisture can hold on long enough before
it dries out. Best precip chances in the CWA look likely to be in
east central WI.

Early next week looks largely dry as a result of dry air and the
fact that a weak ridge will be sliding into the region along with
high pressure sliding through the region. Any precip chances
likely remain well north of the CWA until at least midweek.
Tuesday night through Thursday chances will begin to increase as
shortwave activity increases with increased moisture in the
mid-levels. Still plenty of uncertainty as some models suggest
moisture and better forcing at various times but precip chances at
least mildly increase for that period. The best chance for precip
next week looks to be Thursday related to a fairly strong surface
low and upper level shortwave swing through. Current dryness in
the models complicates precip chance for this time but the forcing
is plenty and moisture can always be a bit more questionable in
the long term. In any case things would be expected to dry out
behind the front Friday as strong high pressure pushes in. Next
weekend shows a bit more potential for activity behind the higher
pressure.

On the temperature front, the next week or so looks to be on the
warmer side as the jet remains north of the region in addition to
the impact of the large scale ridging in the the southwest US.
Best chance for a widespread return to more normal temperatures
comes after the frontal passage Thursday. Onshore lake winds may
keep northeast CWA cooler some days over the next week but the
predominant temperatures are expected to be above normal.

Kuroski

&&

.AVIATION...
Issued 727 PM CDT Fri Mar 20 2026

High pressure will move east of the region tonight, with light
winds expected. Patchy fog may develop for areas toward central
Wisconsin later this evening into early Saturday morning, over
areas that still have a solid snowpack on the ground. Given the
mild airmass over these areas, there may be some fog of 1 to 5
miles and low stratus clouds around 500 feet AGL or lower that
develop. Some dense fog down to 1/4 mile may occur, mainly in
low lying areas. The broken middle to high clouds that are
moving through may deter some of the fog development, so trends
will need to be monitored.

Light southeast to south winds are forecast for Saturday
morning, with the clouds moving out of the area. Winds should
become southwest in the afternoon over south central Wisconsin,
including Madison and Janesville.

There is uncertainty with how far east the gusty southwest
winds develop in the afternoon. If they make it to the lakeshore
terminals, warm temperatures into the 70s will develop. Onshore
winds from the south southeast may linger until early to middle
afternoon for the lakeshore terminals, so the quick wind shift
may warm up temperatures quite a bit in a short amount of time.

Winds are expected to shift to the north and northeast Saturday
night, as a cold front moves south through the area. There may
be light rain with the front (around a 20 percent chance). They
will become gusty later Saturday night into Sunday.

Wood

&&

.MARINE...
Issued 727 PM CDT Fri Mar 20 2026

Winds will become light tonight, as high pressure around 30.3
inches builds in from Ontario. Low pressure around 29.5 inches
develops in the lee of the Wyoming Rockies Saturday morning,
shifting winds south.

There is a chance (around 50 percent) that gusty southwest
winds develop all the way to the lakeshore areas by middle
afternoon Saturday, lingering into early Saturday evening. This
may bring gusts around or above 22 knots at times, so a Small
Craft Advisory may eventually be needed for the nearshore
waters.

The low should move southeastward Saturday night, allowing
winds to increase and shift to the north and northeast across
the northern half of the lake.

The low should move across central Illinois into Indiana
Sunday, as it deepens to around 29.4 inches. This should lead to
northerly winds backing to northwesterly Sunday into Sunday
night across the lake. A few gales are possible during this
timeframe, mainly over southern portions of the lake.

A Small Craft Advisory will likely be needed Sunday into Monday
morning for the nearshore waters, as a result of breezy north
to northeast winds and building waves. High pressure around 30.5
inches should then bring decreasing winds by Monday afternoon.

Wood/Kuroski

&&

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

$$

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