Whitewater, Wisconsin Weather Forecast Discussion

915
FXUS63 KMKX 180245
AFDMKX
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
945 PM CDT Wed Sep 17 2025
.KEY MESSAGES...
- Low chances (15% or less) for a stray shower of thunderstorm
  west of a Monroe / Madison / Fond du Lac line thru Thursday.
- Shower and thunderstorm chances edge eastward into Friday,
  with more widespread 20-50% chances arriving this weekend.
&&
.UPDATE...
Issued 946 PM CDT Wed Sep 17 2025
No major updates to the going forecast. A few areas of patchy
fog are possible in central Wisconsin and the Wisconsin River
Valley areas, but confidence remains low as cloud cover
increases and prevents temperatures from falling to the
dewpoints in those areas. Main concern will be low-lying
regions.
MH
&&
.SHORT TERM...
Issued 300 PM CDT Wed Sep 17 2025
Tonight through Thursday night:
The upper level ridge maintains its foothold in the region
through thursday, hanging on to much of it`s amplitude as well.
With weak surface pressure developing over South Dakota through
Thursday, the majority of the associated showers and
thunderstorms are expected to remain well west of our region,
with very low (generally < 15%) chances for these to push in
west of Monroe / Madison / Fond du Lac.
Expecting dry weather and occasional scattered mid to high
altitude cloud cover through the short term period. A weak (dry)
backdoor cold front sliding down Lake Michigan Thursday may
briefly amplify the lake breeze circulation, producing a 10 to
15 MPH northeast breeze along the shoreline and bordering
counties. Other than that, winds are nearly calm.
Temperatures on Thursday similar to today, with mid 80s inland
and cooler temps by the shoreline thanks to the aforementioned
lake breeze.
Sheppard
&&
.LONG TERM...
Issued 300 PM CDT Wed Sep 17 2025
Friday through Wednesday:
The ridge finally begins to break down into Friday, allowing
shower and storm chances (15-30%) to push into the western half
of the CWA Friday (along and west of a Janesville to Fond du
Lac line). The surface low pressure to our west decays, yet the
upper level low and remnant surface pressure trough / confluence
axis will drift eastward through our region into this weekend,
leading to higher and higher (20-50%) chances for showers and
thunderstorms. The lack of dynamics with this setup would
suggest sub-severe storms, though lightning is certainly still
on the table. Synoptic easterly winds off the lake Friday help
keep temperatures in check (70s east to around 80 inland), and
though winds veer south into the weekend, the cloud cover helps
to hold temperatures around 80 (all areas).
Low predictability in the forecast for the early half of next
week (Mon thru Wed). Some models / ensemble members hint at the
potential for a cutoff low pressure system to extend the shower
/ thunderstorm chances through this period, while others allow
for a more progressive pattern, with subsidence and dry wx.
Sheppard
&&
.AVIATION...
Issued 946 PM CDT Wed Sep 17 2025
Expecting calm winds and VFR cloud cover tonight. A few pockets
of patchy fog reducing visibility to 4-5 SM are possible late
tonight into early Thursday morning, primarily from MSN westward
and in central Wisconsin. Any fog will dissipate shortly after
sunrise. VFR conditions then continue through the remainder of
Thursday, although a very isolated shower or thunderstorm cannot
be ruled out. Expect light southeasterly winds becoming easterly
into Thursday evening.
MH
&&
.MARINE...
Issued 300 PM CDT Wed Sep 17 2025
Low pressure around 29.4 inches will continue eastward across
northern Quebec Canada today, with high pressure around 30.3
inches moving into Ontario through Friday.
Winds remain nearly calm through tonight, with a light northeast
wind developing over the northern half of the lake in response to
a weak backdoor cold front. This front sags southward across the
rest of the lake Thursday, bringing roughly 15 kt north to
northeast winds behind it. Light northeast winds continue into
Friday, becoming breezy and veering southeast Friday night through
Saturday morning as the aforementioned high pressure system
strengthens to around 30.4 inches and approaches southern
Ontario/Quebec and low pressure around 29.9 inches moves into the
Dakotas / Minnesota. There will be chances for thunderstorms
at times this weekend.
Sheppard
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...None.
&&
$$
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NWS MKX Office Area Forecast Discussion