Janesville, Wisconsin 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

573
FXUS63 KMKX 201355
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
855 AM CDT Wed Aug 20 2025

.KEY MESSAGES...

- Overall drier and less humid through the rest of the week.

- Chance for a few isolated to scattered sprinkles area-wide
  through this afternoon.

- A Beach Hazard Statement is now in effect from 7pm today to
  4am Thursday for waves of 3 to 5 feet and dangerous currents.
  It is advised to stay away from piers and breakwalls during
  this time, and avoid swimming at Lake Michigan beaches during
  this time period.

&&

.UPDATE...
Issued 855 AM CDT Wed Aug 20 2025

We will continue to see variable clouds through today as pockets
of low and mid level moisture rotate through the region. A few
sprinkles will remain possible at times. Highs remain on track
to reach the mid to upper 70s.

Boxell

&&

.SHORT TERM...
Issued 240 AM CDT Tue Aug 19 2025

Today through Tonight:

Some surface moisture convergence and impacts from an inverted
surface trough have allowed for some light to moderate showers
across western parts of the CWA this morning. This will likely
gradually weaken and dissipate as it travels SSE, especially as
the inverted trough slides south with higher pressure pushing in
behind. In addition with another night of radiational cooling
with moisture getting trapped under the inversion expect some
fog, becoming more impactful further west. Not expected to see
widespread dense fog at this time but further west may see some
patches to areas of dense fog.

Into the daylight hours, fog should quickly dissipate across the
CWA. By the late morning, with increased northeast winds across
the lake we should see some lakeshore convergence with lighter
and more northerly inland winds. With plentiful moisture from
the surface to 850mb and some semblance of a convergence
boundary even in large scale models now it would seem likely at
least isolated sprinkles to even a few showers would be
possible. Soundings suggest the strongest convergence will be
right around 900mb with fairly strong omega present.

Further west models are also pointing to additional chances for
light showers to drizzle as another surface level inverted
trough factors in. Soundings are much less favorable with much
weaker forcing but this forcing appears focused right at the
surface. Some large scale models show this mild surface
convergence. The key is that low level moisture will be slightly
better further west thus making a few showers/pockets of drizzle
possible. Overall drier conditions will begin to take over by
the late afternoon through the night as the high pressure
begins to become more established with drying low to midlevel
air.

Beach Hazards Statement is now in effect 7pm today to 4am
Thursday for breezy onshore winds causing waves from 3-5 feet.
This will impact Milwaukee, Racine and Kenosha beaches. The
waves during the day today have come down quite a bit and thus
we are holding off on the Beach Hazard until later this evening.
Expect dangerous swimming conditions especially for north
facing beaches, areas near piers and/or breakwalls which will be
most vulnerable to these dangerous currents.

Kuroski

&&

.LONG TERM...
Issued 240 AM CDT Tue Aug 19 2025

Thursday through Tuesday:

Weather is expected to remain quiet and mostly sunny Thursday/
Thursday night as high pressure moves overhead and ridging
remains entrenched across the region. The upper level ridge and
associated sfc high pressure will pull east heading into Friday
morning as a trough moves in from the northwest. This trough
and the associated sfc low in Saskatchewan will move easterly
across the Northern Great Lakes and Ontario. The path of the sfc
low will have int moving from central Saskatchewan toward James
Bay. A cold front associated with this low will move southeast
across Wisconsin Friday bringing some scattered rain and a few
thunderstorms. The cold front is expected to move through Friday
evening, but convergence along the frontal boundary looks
fairly weak. Moisture is also expected to be low as there isnt
expected to much of a moisture return ahead of the front. Winds
will briefly return to southerly Friday morning, but winds will
be light. PWATs are therefore also low. Overall not a great
setup for rain so many people may end up in a hit or miss
scenario with light rain and a few claps of thunder. POPs are
around 10-25% as this cold front moves through.

Cool and dry conditions return behind the cold front. Winds will
remain north to northwesterly from roughly Saturday through early
next week as a ridge builds in from the west and a large occluded
extra tropical cyclone remains in the Hudson Bay area.
Temperatures are expected to fall day by day with highs in the mid
to upper 70s on Saturday becoming upper 60s to low 70s by Monday.

Patterson

&&

.AVIATION...
Issued 855 AM CDT Wed Aug 20 2025

Variable ceilings are expected through the day today. This
morning features a mix of MVFR, IFR, and VFR, but IFR should
become less common through the morning hours, with VFR
eventually prevailing by this afternoon (though some pockets of
MVFR will continue).  Winds will remain out of the northeast.

Boxell

&&

.MARINE...
Issued 240 AM CDT Tue Aug 19 2025

High pressure will remain over the Great Lakes through Friday.
A breezy period of northerly winds will persist through
today as the high moves in behind a retreating low pressure. A
few showers on the west side of the lake will be possible. Light
to moderate north winds are then expected tonight into early
Friday, before winds turn southerly Friday morning head of an
approaching cold front.

Breezy north to northeast winds will bring a period of higher
waves this evening through late tonight with waves up to 5 feet
for the southern 3 tiers of the nearshore. A Small Craft
Advisory remains in effect for this period but has been delayed
due to waves really lacking during the day today in the latest
forecast.

Kuroski

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement...WIZ066-WIZ071-WIZ072...7 PM
     Wednesday to 4 AM Thursday.

LM...Small Craft Advisory...LMZ644-LMZ645-LMZ646...7 PM Wednesday
     to 4 AM Thursday.

&&

$$

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