Area Forecast Discussion
Issued by NWS Green Bay, WI
Issued by NWS Green Bay, WI
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826 FXUS63 KGRB 291742 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 1242 PM CDT Thu Oct 29 2026 Forecast discussion for routine morning forecast issuance .KEY MESSAGES... - Spotty light rain (20-50% chances) for Halloween. Rainfall amounts less than 0.05 inch. Despite the rain, high temperatures will remain slightly above normal in the 50s. - Low pressure brings widespread showers (60-80%) and gusty winds early next week, peaking on Election Day. At least 0.50 inch rain for most. Chances for rain lingers much of next week as the low slowly exits east. - Above normal temperatures continue until late next week. && .DISCUSSION... Issued at 1241 PM CDT Thu Oct 29 2026 High pressure brings cooler temperatures through Friday. Fog risk tonight looks low as some wind will keep low-levels mixed enough. Could have a bit more patchy ground fog Saturday morning, though increasing clouds from the south may restrict radiational cooling needed for that. Spotty light rain for Halloween...Deep trough set up over the eastern Pacific sends a southern stream trough toward the western Great Lakes on Saturday. Not much surface reflection as the departing high holds. However, looking at soundings there is a moist profile below 10kft with weak lift forecast, suggesting that though chances of measurable rain (0.01") will be under 50%, drizzle or very light trace amounts of rain may occur beneath a mostly cloudy sky. Ensembles support this idea showing 30-60% chance of seeing at least a trace of rain, greatest over central Wisconsin. But, not looking at any kind of washout for outdoor activities. Even with the clouds and some rain, high temperatures will still reach the mid to upper 50s which even though cooler than lately, will be above average. Stronger system with widespread rain early next week...After some dry weather returning Sunday into start of Monday, larger scale troughing shifts across the plains and moves into the Great Lakes-Ohio Valley. Surface low is well agreed upon from ensembles from ECMWF, GFS, and Canadian to track across northern Ohio Valley, placing Wisconsin in regime that will bring periods of rain from late Monday through Wednesday as the system slowly crosses. Peak of rain and gusty winds will be Tuesday, Election Day, but unsettled weather will be slow to unwind the rest of the week behind the departing low. Chances for exceeding 0.50 inch rain Monday Night through Tuesday are up to 70%, while chances for exceeding 1.00 inch are up to 40-60%. Higher end projections take rainfall to 1.5 to 2.0 inches. Certainly looks like a soaking rain at times. Dynamics may be strong enough for some embedded thunder as the initial warm air advection rain arrives on Monday night. Temperatures will remain above normal the next week, though a bit of a cooldown (temperatures returning to around normal) occurs late next week after the low pressure system passes by. Available long range guidance points to above normal temperatures through most of November. Official forecast for meteorological winter (Dec through Feb) also favors above normal temperatures which is right in line with the ongoing very strong El Nino. && .AVIATION...for 18Z TAF Issuance Issued at 1241 PM CDT Thu Oct 29 2026 Skies will be mostly clear into tonight, except at RHI where SCT- BKN MVFR stratocu will linger on edge of more widespread cloud field. Late tonight through midday Friday, the stratocu will diminish at RHI, but as this occurs a swath of SCT-BKN mid-level altocu (100-120) will spread across all the TAF sites, along with some cirrus. WNW-NW winds will remain gusty (up to 23 kts) through 22z-24z. Tonight into Friday will feature NW winds around 5 kts as high pressure builds in from the northwest. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....JLA AVIATION.......JLA