FXUS63 KGRB 201114 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 614 AM CDT Fri Mar 20 2026 Updated aviation portion for 12Z TAF issuance .KEY MESSAGES... - Areas of dense fog possible this morning across central to north- central Wisconsin. - Next chance of a wintry mix and snow (20-40%) Saturday night into Sunday, especially over northern Wisconsin. - Temperatures surging above normal today and Saturday, with the warmth peaking Saturday (mid to upper 50s). - Snowmelt and increased flows and rising levels on rivers and streams are expected. Several rivers may reach bankfull or even minor flood stage beginning this weekend. && .DISCUSSION... Issued at 122 AM CDT Fri Mar 20 2026 A clipper system will bring some light rain to far northeast Wisconsin early this morning, with snow and freezing rain possible near the Michigan border. In addition, some patchy fog will be possible later this morning with abundant low level moisture over a cold snowpack. The worst visibility restrictions are expected across central and north-central Wisconsin, where locally dense fog is possible. Dry weather is then expected the rest of today as temperatures continue their climb across the western Great Lakes region. Highs today are expected to range from the lower to middle 40s across the Fox Valley with around 50 degrees north and west of the Fox Valley where NBM probabilities of exceeding 50 degrees are 50-80%. Saturday will likely be the warmest day of the week as an approaching low pressure system from the Plains brings a surge of warm air over the western Great Lakes region. NBM probabilities of exceeding 60 degrees have increased to 40-80% southwest of a line from Mosinee to Oshkosh. The rest of the area will likely see temperatures in the 40s across far northeast Wisconsin, with 50s in between these areas. Precipitation on Saturday will mainly be limited to far northern Wisconsin near the Michigan border associated with isentropic lift near the warm front. The cold side of this low pressure system will track through the area Saturday night, bringing colder temperatures and a rain/snow mix as a cold front sinks south through Sunday. The chance of precipitation is 20-40%, with most of the precipitation occurring on Saturday night. NBM 24 hour probabilities for accumulating snow have trended down precipitously and are currently de minimis, clocking in at 10% or less across far north-central and northeast Wisconsin ending Sunday evening. High pressure will then provide dry weather to the area early next week. Temperatures will start off at or slightly below normal, but quickly rebound to slightly above normal by the middle of next week. A clipper system will also be moving through the middle of next week. This system has a lot of uncertainty surrounding it, as evidenced by the large spread in probabilistic data. Current 24 hour NBM probabilities for an inch or more of snow during the middle part of next week are 20-30% across north- central Wisconsin. && .AVIATION...for 12Z TAF Issuance Issued at 613 AM CDT Fri Mar 20 2026 Main concern this morning is MVFR and possible IFR fog across central and north-central Wisconsin TAF sites. Any fog should clear up by 14/15Z with VFR conditions expected the rest of today. Winds will generally be west to northwest below 10 knots, with a lake breeze boundary turning winds southeast across east-central Wisconsin and affecting KGRB/KATW/KMTW this afternoon. Areas of fog are expected again tonight into Saturday morning, dropping conditions to MVFR/IFR. && .HYDROLOGY... Issued at 122 AM CDT Fri Mar 20 2026 As temperatures warm across the region, the snowmelt will result in increasing fast flows and rising river levels. Some rivers could reach bankfull or even minor flood stage. The lack of a rapid, significant warmup points to a more gradual rise in area rivers as opposed to widespread rapid rise flooding. That being said, the flooding situation will be monitored closely given how much water is locked up in the current snowpack across the region. Latest Snow Water Equivalent (SWE) here at our office is now 2.88 inches with a snow depth of 14 inches. This matches the current NOHRSC snow depth and SWE analysis pretty well. Modeled snowpack temperature from the NOHRSC site points to ripening of snowpack (really starting the melting/runoff process) over central WI as early as today, with more widespread ripening of snowpack up over the area on Saturday. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....Kurimski AVIATION.......Kurimski HYDROLOGY......Kurimski