024
FXUS63 KGRB 270140
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
840 PM CDT Wed Aug 26 2026

New Information added to update section

.UPDATE...
Issued at 838 PM CDT Wed Aug 26 2026

Right on schedule, the last of the showers have exited southeast
CWA. Even though skies will not completely clear out and winds
will not go calm tonight, CAM and MOS visibility guidance
suggests at least patchy fog forms late tonight north-central WI.
Expanded the coverage some, even though this looks more like
shallow ground fog.

Backdoor front dropping in for Thursday afternoon did generate a
few showers today north of Lake Superior. Though moisture layer
is thin in forecast soundings, there was enough support to add
some sprinkles in the afternoon, especially far northeast WI.

Better signal for fog shows up for Thursday night as high pressure
is overhead. Added mention of fog to the forecast. Could see this
being areas, but kept it patchy fog now.

&&

.KEY MESSAGES...

- Patchy ground fog late tonight over north-central WI, with areas
  of fog possible in the same areas late Thursday night.

- Next chance of showers and storms arrive Friday night and
  Saturday, and then continue into early next week. Details are
  still murky when the best chances of rain would occur and if
  there would be the potential for stronger storms.

&&

.DISCUSSION...
Issued at 138 PM CDT Wed Aug 26 2026

Scattered showers and a few thunderstorms were occurring across
northern WI and Upper Michigan this afternoon. The scattered
showers and storms will continue for much of the rest of the
afternoon, with a gradual southward progression of the rain
during the latter half of the afternoon. Based on model
soundings, inverted V structure in the low levels of the sounding
would suggest gusty winds to 40-45 mph are still possible with
the stronger showers and storms along with brief heavy rain.
Any lingering rain should end early this evening with clearing
skies during the night with lows mainly in the 50s with 60s along
the bay and Lake Michigan.

Dry conditions should prevail on Thursday. The only concern is a
backdoor front will move across northeast Wisconsin during the
afternoon where that may be the focus for an isolated shower or
storm. Dr conditions prevail on Friday. The forecast becomes
muddled late Friday night through the weekend. There appears there
will be a few rounds of showers and thunderstorms over the weekend
into early next week. This would be good news to help alleviate
the drought across our area. Latest model runs suggest the first
round of showers and would arrive late Friday night into Saturday.
There is a lot of questions in where convection would set up as
the ECMWF/Canadian model support convection mainly across the
north through Saturday afternoon. The GFS/NAM were further south.
The uncertainties then persist through the rest of the weekend
into the middle of next week. It is hard to quantify the severe
weather risk due to the differences in the model output this far
out. Potential for heavy rain is there with the few rounds of
storms.

For temperatures, a cool night is in store across the north
Thursday morning with lows in the 40s. Otherwise, temperatures
should rise to above normal levels over the weekend into the first
half of next week.

&&

.AVIATION...for 00Z TAF Issuance
Issued at 628 PM CDT Wed Aug 26 2026

Isolated showers could occur through 01z-02z, then intervals of
scattered mid clouds (050-070) will linger through the night. Fog
may develop at RHI late. Based on cooling/saturation expected,
went with IFR vsby, though this has the looks of thin patchy
ground fog (MIFG). On Thursday, reinforcing cold front nearby may
pop a few sprinkles during peak heating. Main result though will
be enhancing a VFR cu field late morning into the afternoon.

Gusty NW winds diminish to 5-10 kts late evening through the
overnight. NW winds less than 10 kts expected on Thursday, though
a few gusts to 15 kts will occur central to north-central WI.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

UPDATE.........JLA
DISCUSSION.....Eckberg
AVIATION.......JLA

NWS GRB Office Area Forecast Discussion