Fond Lac, Wisconsin 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

017
FXUS63 KMKX 201325
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
825 AM CDT Fri Jun 20 2025

.KEY MESSAGES...

- Hot and humid conditions are expected Saturday through Monday.
  Maximum heat indices of 100 to 105 degrees are forecast each
  day. Highest confidence in reaching 105 degree heat index in
  southeast WI. An Extreme Heat Warning is in effect for
  Milwaukee, Racine, and Kenosha Counties.

- Cold front arrives next Monday into Tuesday, but then lingers
  as a boundary through much of next week.

&&

.UPDATE...
Issued 8 AM CDT Fri Jun 20 2025

Remnant MCV from an overnight system is currently working
through southern Wisconsin which is bringing a 1-2 hour period
of light to moderate rain to this region. Not seeing much
lightning activity with this, but did see some earlier with the
batch going through east central WI which is more tied to some
700mb forcing. Current expectations are that when this area of
rain moves through that things should clear out and the rest of
the day should be storm-free.

Halbach

&&

.SHORT TERM...
Issued 337 AM CDT Fri Jun 20 2025

Today through Tonight:

Clusters of convection are currently ongoing over north central
Wisconsin and portions of the Upper Mississippi River Valley in
association with 850mb warm advection and an elevated
instability gradient over the Western Corn Belt. The activity
over northern Wisconsin, following the 850mb warm advection, has
largely struggled to move into our CWA, generally dying as it
moves across the Winnebago/Fond du Lac County border. Models
depict this activity largely moving east and dying through the
morning, although the modeled movement is not quite
representative of reality. This likely due to the activity
following the Corfidi Vectors, rather than the 500mb flow. Thus,
there is the potential for this 850mb driven activity to clip
east central WI this morning. Most of the activity has mellowed
with time this morning but, while severe weather is not
expected, pea-sized hail can`t be ruled out given colder air
aloft.

Further west, a stronger MCS is ongoing over Iowa, more closely
following the Corfidi vectors. This will likely bring the MCS
into southwest Wisconsin, with the strongest convective elements
staying west of our CWA. Still, a few rumbles of thunder may
occur and stratiform rain will move over most of southern WI
from this activity through most of the hours between dawn and
noon.

This afternoon, we`ll likely dry out as any surface boundaries
wash out/lift north and trigger storms far to our north over the
U.P. Highs will peak in the low to mid 80s, with increasing
humidity tonight as a moist air mass lifts northeast into the
area beneath a strong ridge axis.

CMiller

&&

.LONG TERM...
Issued 319 AM CDT Fri Jun 20 2025

Saturday through Thursday:

Overall the trend for hot and muggy weekend continues with the
upper- level ridge axis overhead. The 00z HREF is now within range
for at least Saturday and supports the trend of daytime temps in
the 90s along with seeing high potential (>70%) of heat indices
approaching and even exceeding the triple digit. Expecting to see
similar conditions, if not a few degrees hotter for Sunday.
Overall, the highest confidence for triple digit heat indices
remains in southeast WI due to the strong southwesterly winds
contributing to a localized downslope effect off the kettle
Moraine warming temps a few degrees more than other areas. Thus
will maintain the Extreme Heat Watch in southeast WI. However, a
Heat Advisories for other surrounding areas will likely accompany
any upgrades. In addition to the hot daytime temps, overnight lows
are forecast to remain warmer than normal in the mid to upper 70s
both Saturday and Sunday nights.

It will be possible that record high and/or record warm low
temperature records are set over the weekend. Record high temps
are more likely at MKE than MSN, but warm low temp records are
possible at both locations.

Heat is increasingly likely to linger into Monday as the ridge
axis slides further east. May not see quite as warm of temps and
heat indices, but it still looking at hot and muggy day with low
to mid 90 temps and upper 90 heat indices and even a few spots
around the 100F mark. Meanwhile an upper-level trough will begin
to dig across the northern Plains and will move into the the Upper
Midwest later Monday/overnight. It will be accompanied by a
weakening surface low lifting northeast dragging a cold front
across WI during this time frame as well. With the elevated
moisture, heat and forcing along the front will bring increased
shower and thunderstorm chances as well. Long range models
continue to hint at this front stalling somewhere across the
Midwest, but continued run to run variability makes it hard to
pinpoint. So will need to keep an eye on how and where it sets up
next week as additional shower/storm chances will be possible
along it.


&&

.AVIATION...
Issued 825 AM CDT Fri Jun 20 2025

VFR conditions in place across southern Wisconsin and are
expected through Saturday as low level winds increase out of the
south as a ridge of high pressure builds in. The main focus will
be on winds as they increase out of the south today into
tomorrow.

Halbach

&&

.MARINE...
Issued 320 AM CDT Fri Jun 20 2025

A stationary front will slowly lift north today, and southerly
winds will be prevalent over most of the lake, with modest breezes
to 20 knots.

Tonight, a secondary warm front will lift north, and a strong low
level jet will bring gusty southerly winds over the lake into
Saturday night. Right now, it appears that a strong inversion over
the lake will impede wind speeds from reaching gale force, but the
large amount of momentum a few hundred feet above the lake surface
will likely cause wind gusts to at least 30 knots.

Gusty south to southwest winds will then linger into Sunday as low
pressure of 29.3 inches slowly approaches Lake Superior from the
Central Plains by Monday morning.

CMiller

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Heat Advisory...WIZ046-WIZ047-WIZ051-WIZ052-WIZ056-WIZ057-
     WIZ058-WIZ059-WIZ060-WIZ062-WIZ063-WIZ064-WIZ065-WIZ067-
     WIZ068-WIZ069-WIZ070...noon Saturday to 7 PM Monday.

LM...None.
&&

$$

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