031 FXUS63 KGRB 060241 AFDGRB

Area Forecast Discussion National Weather Service Green Bay WI 941 PM CDT Fri Sep 5 2025

New Information added to update section

.UPDATE... Issued at 936 PM CDT Fri Sep 5 2025

No major changes to forecast late this evening. Latest models, especially the HRRR and RAP, still point to expansion of light showers and/or sprinkles over northeast WI late tonight (3am-6am) as forcing increases with shortwave approaching from the west. Already incorporated these trends into earlier update this evening. At the high-end, only looking at 0.05-0.10 inch of rain, but for most probably only will be a trace to a few hundredths. Winds are diminishing, with main exception over northern Door County/Washington Island with flow off Bay of Green Bay.

Temps still on track from earlier, with clouds and some wind limiting risk of any frost over the north even if temps can manage to drop into the mid to upper 30s. Readings of 38-40f are most likely though.

.KEY MESSAGES...

- Scattered to isolated showers through Saturday, with the greatest chances in north-central Wisconsin.

- Near-record cold maximum temperatures are possible through this weekend. Frost potential Sunday and Monday morning. Moderating temperatures early next week, but remaining below normal.

.DISCUSSION... Issued at 222 PM CDT Fri Sep 5 2025

Cyclonic flow, gusty westerly winds, along with light showers and sprinkles will continue this evening as a shortwave, seen on water vapor imagery over South Dakota, tracks east through Wisconsin. Winds will ease a bit later tonight behind the departing shortwave as showers and sprinkles become less numerous. The best chance for showers will be across north-central Wisconsin tonight with added moisture from Lake Superior.

Additional shortwaves will provide more opportunities for light rain showers and sprinkles Saturday into Saturday evening. An upstream high pressure system will build in from the west, which will bring a drying trend to the region late Saturday night into Sunday.

The high will track east Sunday night, allowing for return flow on Monday. An approaching cold front will bring the next chance for showers and thunderstorms to the region from Monday night through Tuesday evening as it slowly tracks through the area. High pressure should then keep the rest of the week dry.

Temperatures/Frost Potential...An abnormally cold airmass will continue to reside over the area through the weekend, resulting in well below normal temperatures. Several sites are expected to set new record low maxes for today, with additional records potentially in jeopardy on Saturday. See the climate section for more details about records. The addition of the surface high pressure system moving into the region Sunday into Monday, may allow for a couple periods of frost development in portions of the region Sunday morning and Monday morning with low temperatures forecast in the mid 30s to low 40s. The return flow early next week will allow temperatures to rise into the 60s and low 70s, but remain below normal.

.AVIATION...for 00Z TAF Issuance Issued at 625 PM CDT Fri Sep 5 2025

All the TAF sites could see a light shower or sprinkle this evening, but the coverage is too isolated and brief to include. However, there is a decent signal that expansion of light rain, sprinkles occurs 08z-11z over northeast WI, mainly impacting GRB/ATW so have added mention to latest TAFs. No reduction to vsby is expected. CIGS will mainly be VFR through the period at all TAF sites, though RHI will see occasional MVFR cigs (020-030) tonight.

Gusty westerly winds with gusts over 20 kts will gradually diminish late this evening, then increase again Saturday morning with gusts to around 15 knots.

.MARINE... Issued at 939 PM CDT Fri Sep 5 2025

Westerly winds are still gusting to 25 kts over the bay and near Death`s Door. Winds have diminished elsewhere. A Small Craft Advisory remains in effect for the bay and nearshore waters north of Sturgeon Bay through midnight. Small Craft Advisory has been cancelled early over the rest of the Lake Michigan nearshore waters. Beyond midnight, expect winds and waves to remain below headline criteria for the rest of the weekend.

.CLIMATE... Issued at 222 PM CDT Fri Sep 5 2025

The unseasonably cold airmass will bring additional chances of setting record low maximum temperatures on Saturday (9/6). Here is a look the current records and forecast values for Green Bay, Rhinelander, and Wausau.

Green Bay

Date Record Low Max Forecast High ---- -------------- -------------

9/6 58F(1965) 60F

Rhinelander

Date Record Low Max Forecast High ---- -------------- -------------

9/6 55F(1956) 56F

Wausau

Date Record Low Max Forecast High ---- -------------- -------------

9/6 56F(1965) 58F.

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

UPDATE.........JLA DISCUSSION.....Kurimski AVIATION.......JLA MARINE.........JLA CLIMATE........Kurimski

NWS GRB Office Area Forecast Discussion