Lappe Nordic Centre Snow Report

809 FXUS63 KGRB 290630 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 130 AM CDT Tue Sep 29 2026 Forecast discussion for routine morning forecast issuance .KEY MESSAGES... - Patchy dense ground fog will be possible this morning, with localized reductions in visibilities to less than one half mile. - Widespread soaking rainfall is expected over most of the area from this evening through Thursday afternoon. Rainfall amounts between 1 and 1.5" are forecast across portions of central and east-central Wisconsin. - Patchy frost will be possible at times across northern Wisconsin later this week as a cooler and drier airmass settles in. && .DISCUSSION... Issued at 100 AM CDT Tue Sep 29 2026 Fog potential... Latest surface obs show patchy ground fog developing over portions of central and far northeast Wisconsin late tonight as winds decouple and boundary layer saturation occurs. However, CAMs still not showing a clear signal for dense fog development into the early morning hours, with equal chances of manifesting as low stratus as gradient winds increase. Will continue to monitor trends over the next several hours to see if a Dense Fog Advisory may be needed. Heavy rain... Widespread stratiform rain is still on track for much of northeast Wisconsin tonight through Thursday as upper low interacts with the remnants of Hurricane Polo to create a moisture-rich environment from the central Plains into the Midwest. As such, PWATs increase to around 1.75 to 2" (99th percentile relative to climo) Wednesday into Thursday as forcing is maximized along a frontal boundary. Probabilistic guidance holds steady at a 30 to 60% chance for receiving 2 inches of QPF during the 48-hour period from Tuesday afternoon through Thursday afternoon, though this is more of a glancing blow to our southern tier of counties where better moisture return is. WPC highlights areas along/south of Hwy 10 in a slight risk for excessive rainfall on Wednesday, though current thinking is that prolonged rainfall duration and current drought status would mitigate flooding concerns in our neck of the woods. Some rumbles of thunder will be possible at times on Wednesday as MUCAPEs reach 100 to 200 J/kg, though any organized convection is not expected. If anything, meager instability would aid in higher rainfall rates during this time. Extended... Subsidence behind the front will usher in surface high pressure late on Thursday, which should stick around for the better part of the extended. As such, expect a pattern shift to cooler and drier weather, with the exception of 20 to 30% chance of rain on Saturday. With surface high sitting overhead and falling temperatures, conditions should be favorable for effective radiational cooling and frost development at times during the early morning periods throughout the week. Will continue to monitor trends for headline potential as we approach the end of the growing season. && .AVIATION...for 06Z TAF Issuance Issued at 1057 PM CDT Mon Sep 28 2026 Clear skies, light winds, and some high clouds are expected through Tuesday morning. Patchy dense ground fog/stratus is expected to develop overnight, with impacts of MVFR to LIFR vsbys occurring between 09z-13z Tue. Confidence remains highest for the lowest vsbys occurring at RHI/GRB. Confidence is lowest at ATW/MTW. Any fog will burn off by mid-morning Tuesday as high and mid clouds spread over the area ahead of the next rain producing system. Southerly winds will increase Tuesday afternoon with gusts of 15-20 kts, highest at RHI. The rain will spread into the area from the west during the late afternoon, reaching the east- central WI TAF sites after 00z Wed. Cigs will quickly drop from MVFR to LIFR at the central and north-central WI TAF sites after 01z Wed with the rain. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....Goodin AVIATION.......Kruk