Ephraim, Wisconsin Weather Forecast Discussion

187
FXUS63 KGRB 231127
AFDGRB
Area Forecast Discussion
National Weather Service Green Bay WI
627 AM CDT Tue Sep 23 2025
Updated aviation portion for 12Z TAF issuance
.KEY MESSAGES...
- Areas of fog this morning will affect the morning commute.
  Areas of fog may develop again tonight. The fog could impact the
  Wednesday morning commute over portions of the area.
- Marine fog will be dense at times this morning. Marine fog may
  develop again tonight.
&&
.DISCUSSION...
Issued at 306 AM CDT Tue Sep 23 2025
Short Term...Today...Tonight...and Wednesday
Satellite and METAR observations indicate an area of dense fog has
settled in across far northeast Wisconsin and creeped in across
portions of central and east-central Wisconsin early this morning
with a smaller area confined to portions of north-central
Wisconsin. Will continue the Dense Fog Advisory this morning
across the areas where the densest fog has been the most
persistent. These areas of fog should dissipate throughout the
morning as the sun rises and turbulent mixing erodes the fog.
Later this afternoon light showers are possible (20% chance) as a
mid level shortwave embedded in the cyclonic upper level flow
tracks through the western Great Lakes region. Highs this
afternoon are expected to range from the middle to upper 60s
across north- central Wisconsin, to the lower 70s across central
Wisconsin.
Abundant low level moisture will likely lead to another round of
dense fog tonight, especially across north-central Wisconsin with
additional low level moisture from Lake Superior. Lows tonight are
expected to generally be in the 50s.
The upper low will sink south across the central Great Lakes on
Wednesday, as the region remains in cyclonic flow. Showers will
once again be possible as a shortwave tracks through the region
with the best chance (20% chance) across east-central Wisconsin
and the lakeshore closest to the dynamic forcing. Highs on
Wednesday are expected to range from the middle 60s across the
north to around 70 across central Wisconsin.
Long Term...Wednesday Night Through Monday
A period of low impact and quiet weather is in the forecast for
the extended period starting Wednesday night through the weekend.
Upper level flow during this time flattens out over our area, with
predominantly zonal flow across the Great Lakes. The only
potential weather maker at this time would be a low pressure
system that crosses Canada to our north Friday night into
Saturday, bringing a cold front through our region early on
Saturday. At this time we remain dry given the timing and relative
lack of moisture, but if this system shows signs of dipping
southwards over the next few days, some light pops may yet work
their way into the forecast. With no major air mass exchanges in
the works for the extended, temperatures will hold fairly steady
with highs in the upper 60s to mid 70s during the day and lows in
the upper 40s to lower 50s.
&&
.AVIATION...for 12Z TAF Issuance
Issued at 627 AM CDT Tue Sep 23 2025
Low stratus clouds and dense fog will mix out during the morning
as conditions improve to MVFR and eventually VFR by this
afternoon. Low stratus and fog are expected to develop again
tonight, with the lowest conditions across north-central
Wisconsin where IFR/LIFR conditions are possible. Isolated showers
are possible this afternoon across east-central Wisconsin with
coverage too low to include in any of the TAF sites.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 7 AM CDT this morning for WIZ005-018-
022-031-037>040-073-074.
&&
$$
DISCUSSION.....Kurimski/Uhlmann
AVIATION.......Kurimski

NWS GRB Office Area Forecast Discussion