FXUS63 KGRB 151726 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 1226 PM CDT Thu Oct 15 2026 Updated aviation portion for 18Z TAF issuance .UPDATE... Issued at 225 AM CDT Thu Oct 15 2026 Upgraded the Gale Watch to a Gale Warning for the bay and our nearshore waters of Lake Michigan from 8 am to 9 pm Friday. The Gale Warning was started a few hours early to cover the ramp up of hazardous small craft due to increasing winds and waves until gale force gust arrive late Friday morning and continue through the afternoon. && .KEY MESSAGES... - Widespread rain arrives Thursday afternoon, and will continue at times through Friday. Expect most areas to see between 0.5 and 1" of total rainfall. - Northwest winds increase on Friday, with gusts between 35 and 45 mph possible. Gale force gusts expected across marine zones. - A widespread frost/freeze event is expected Friday night into early Saturday morning. - A warming trend and breezy southwest winds will bring daytime high temperatures back into the 60s late this weekend, with minimal rain chances through mid-week. && .DISCUSSION... Issued at 1000 PM CDT Wed Oct 14 2026 Rain chances Thursday/Friday... Biggest change from previous forecast cycles centers around a noticeable jump in QPF amounts Thursday through Friday as models hone in on timing/evolution of the upper pattern. Signs still point toward phasing of northern and southern stream lows over the western Great Lakes Thursday night as a deepening surface low ejects from the central Plains. Jet energy ramps up during this time as moisture plume (near 99th percentile PWATs) interacts with mid-level FGEN in proximity to low pressure over southern Wisconsin. As such, probabilities for receiving one inch of QPF now stand at a widespread 30 to 60%. Thus expecting a soaking rainfall across most of northeast Wisconsin, which will be beneficial to areas across the north that have been in an extended period of drought. Stratiform rain then becomes more scattered in coverage on Friday, though wrap around moisture should keep at least light rain around for most of the day. Temperatures... Following a decent stretch of seasonable weather, cold FROPA and intrusion of arctic high will bring a brief spell of well below normal temperatures from the Plains to the Midwest on Friday. 850 mb temperatures plunge to around 2 to 5C below zero, which will translate to high temperatures reading in the mid 40s across the north to the mid 50s in the Fox Valley. Overnight lows will then fall into the mid 20s to low 30s inland of Lake Michigan, pointing toward a high confidence setup for frost/freeze under clearing skies and light winds. If trends hold, expect most areas to see a hard freeze that would effectively put an end to the growing season. Expect headlines to be forthcoming in the next day or so. Return flow then quickly sets up over the weekend, resulting in high temperatures rebounding into the 60s. Extended... High pressure looks to be the main driver of the synoptic pattern through at least the middle of next week, with no organized systems on the horizon. More active pattern looks to set up beyond then as upper flow re-amplifies, though details are few this far out. && .AVIATION...for 18Z TAF Issuance Issued at 1226 PM CDT Thu Oct 15 2026 Flying conditions will continue deteriorating to primarily IFR for the rest of today and tonight, with some improvement to MVFR late in the TAF period on Friday morning. Ongoing widespread rain will move northeast into the rest of northeast WI over the next 1-2 hours; and then persist for the afternoon and evening, leading to low cigs and vsbys. Temporary dips to LIFR over the next 12 hours with cigs right around the 500 ft threshold. Rain transitionsto scattered to isolated coverage after 06Z/Fri, but low cigs and vsby remain. Improvements to MVFR occur around or after 09Z/Fri as ceilings rise and patchy fog clears out, but as this occurs NW winds increase, with gusts up to 30 kts. LLWS is also present at 2kft for central and north-central WI on Friday morning. && .MARINE... Issued at 1000 PM CDT Wed Oct 14 2026 Upgraded the Gale Watch to a Gale Warning for the bay and our nearshore waters of Lake Michigan from 8 am to 9 pm Friday. The Gale Warning was started a few hours early to cover the ramp up of hazardous small craft due to increasing winds and waves until gale force gust arrive late Friday morning and continue through the afternoon. From the previous discussion: Gradient winds on the back edge of the departing surface low ramp up Thursday night into Friday morning, putting us solidly within northwest flow and CAA regime. Deep daytime mixing will tap into 45 to 50 knot winds at 850 mb Friday afternoon, which will result in a brief window for gale force gusts over all marine zones through Friday evening. NBM probabilistic guidance continues to show a healthy signal (60 to 90%) for gusts exceeding 38 mph, highest along the Lake Michigan nearshore waters south of Kewaunee. Waves build 6 to 9 ft on the Lake and 3 to 6 ft on the Bay during this time, subsiding Friday night as winds shift to more westerly and the pressure gradient eases up. Gale Watches remain in effect. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE.........Eckberg DISCUSSION.....Goodin AVIATION.......KLJ MARINE.........Goodin/Eckberg