FXUS63 KGRB 221136 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 636 AM CDT Sat Aug 22 2026 Updated aviation portion for 12Z TAF issuance .KEY MESSAGES... - Isolated to scattered showers and storms (30-50% chance) expected over north-central to eastern WI, mainly in the afternoon. A strong storm with gusty winds and hail is possible. - Dry weather returns Sunday and Monday, with a period of unsettled weather arriving for the middle of next week. - Slightly below normal temps this weekend, then a return to near normal readings for most of next week. && .DISCUSSION... Issued at 126 AM CDT Sat Aug 22 2026 This Weekend...Recent rainfall, mostly clear skies and light winds has led to some patchy ground fog development, especially across northern WI. Some clouds moving in should help keep the fog in check, but at least some patchy fog will continue early this morning, then burn off after sunrise. Northwest, cyclonic flow will prevail across the Great Lakes through the weekend with a couple shortwaves moving with this flow bringing chances for a few showers and storms. The first weak shortwave arrives this morning, bringing a stray shower or sprinkle across far northern WI. A second shortwave will dive across northeast WI this afternoon, bringing isolated to scattered showers and storms (20-50% chance) mainly to far northern and eastern WI. While weak deep layer shear (under ~25 kts) will limit overall organization of the storms and the severe threat, SBCAPE of up to ~1200 J/kg, inverted-V soundings and very steep low-level lapse rates will promote some gustier winds and small hail in the stronger showers/storms. Northwest winds will increase to 15 to 25 mph this morning and afternoon. Surface high pressure and drier air will keep the area dry tonight into Sunday. Northwest winds will be a little lighter on Sunday, but still gust to 20 mph. Next Week...Dry weather continues on Monday, then another shortwave trough is forecast to move across the region late Tuesday into Wednesday, bringing the next chance (40-65%) for showers and thunderstorms. Instability appears modest with this mid-week feature, keeping severe probabilities low. Temperatures...Temps this weekend will dip a little below normal as northwest flow prevails, with highs mainly in the 70s to near 80 (with a few upper 60s over far northern WI on Sunday). A couple chilly nights are in store this weekend, especially across northern WI where lows will dip into the upper 30s to low 40s. Temps nudge back to near or slightly above normal for much of next week with highs mainly in the mid 70s to low 80s. && .AVIATION...for 12Z TAF Issuance Issued at 636 AM CDT Sat Aug 22 2026 Patchy ground fog will burn off shortly after sunrise, with some other mid clouds moving across eastern WI. While a few lower clouds could move into far north-central WI this morning, expect low end VFR clouds to build with daytime heating in the 15-16Z timeframe. Isolated showers should develop over far northeast WI in the 20-00Z timeframe, but coverage will be limited, so have kept the PROB30 going at GRB/MTW/ATW. A stray storm is also possible, but chances are too low to include. Only a few lingering clouds are expected after dark and into tonight. Northwest winds will increase this morning and become a bit breezy, with gusts to 20 kts in the late morning and afternoon, then easing to under 10 kts after sunset. && .MARINE... Issued at 126 AM CDT Sat Aug 22 2026 Northwest winds of 10-20 kts are expected this weekend. Gusts to 25 kts will be possible, mainly near Death's Door. HREF 10m gust ensemble mean and max bring 25 kt winds right to Washington Island, but keep the stronger winds towards northern Lake Michigan. Due to the very smallarea and marginal winds, will hold off on issuing a Small Craft Advisory. Offshore winds will limit waves to 1 to 3 ft for most spots on the bay and nearshore waters, with any 3-4 foot waves staying in the open waters. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....Bersch AVIATION.......Bersch MARINE.........Bersch