605 FXUS63 KGRB 282302 AFDGRBArea Forecast Discussion National Weather Service Green Bay WI 602 PM CDT Sun Sep 28 2025
Updated aviation portion for 00Z TAF issuance
.KEY MESSAGES...
- An extended period of dry and low-impact weather is forecast through the next week. Above to much above average temperatures are expected during this time frame.
&&
.DISCUSSION... Issued at 239 PM CDT Sun Sep 28 2025
High pressure and a very dry air mass (PWAT of 0.42 inch on the 12z GRB RAOB) have resulted in sunny skies across the forecast area this afternoon. The sunshine, combined with light south winds, allowed temperatures to warm into the lower to middle 70s at most locations.
With the very dry air mass in place, only expecting patchy ground fog development late tonight into early Monday morning. Have continued to side with the cooler guidance for low temperatures, with readings ranging from the upper 30s/lower 40s in the cool spots of north central WI, and 40s to lower 50s elsewhere. Another mostly sunny day is anticipated on Monday, with southwest winds boosting highs into the upper 70s to middle 80s. A weak cold front drops south across the region Monday night, with greater potential for patchy/areas of fog as a shallow cooler air mass arrives and winds become light from the east to northeast.
Canadian high pressure will ridge across the Great Lakes region through the rest of the week, and will be slow to shift east due to the blocking influence of a couple tropical systems in the western Atlantic. The frontal passage will bring a minor cooling trend mid-week, followed by much above normal temperatures into the early part of the weekend. Dry conditions persist through at least Saturday or Saturday night, followed by a chance of showers as a slow-moving cold front arrives for the late weekend and early part of next week.
Winds will pick up a bit out of the southeast Wednesday night into Thursday, leading to possible marine concerns (Small Craft Advisories) on Lake Michigan, especially south of Two Rivers.
&&
.AVIATION...for 00Z TAF Issuance Issued at 602 PM CDT Sun Sep 28 2025
High confidence in VFR conditions for all terminals (KGRB, KATW, KMTW, KAUW, KCWA, KRHI) through the period. A dry airmass and high pressure will result in clear skies and light winds.
The only potential for sub-VFR conditions is some patchy ground fog toward sunrise Monday. The risk is very low for most sites, but KRHI and perhaps KMTW have a slightly higher chance for a brief period of IFR or MVFR visibilities between 08Z and 12Z. Otherwise, expect clear skies and calm winds overnight, becoming E/NE at 5-10 KT on Monday afternoon.
OUTLOOK... MVFR/IFR conditions possible Monday night into Tuesday morning due to ground fog/low stratus.
&&
.GRB WATCHES/WARNINGS/ADVISORIES... None.
&&
$$
DISCUSSION.....Kieckbusch AVIATION.......MPC
NWS GRB Office Area Forecast Discussion