FXUS63 KGRB 200346 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 1046 PM CDT Thu Mar 19 2026 Updated aviation portion for 06Z TAF issuance .KEY MESSAGES... - Wintry mix tonight near the Michigan border. Minimal snow and ice accumulation expected. - Areas of fog tonight into Friday morning central to north- central WI. - Next chance of a wintry mix and snow (30-50%) Saturday night into Sunday, especially over northern WI. - Temperatures surging above normal into 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 201 PM CDT Thu Mar 19 2026 NW flow will bring a couple of clipper systems to the region. The first occurs tonight into Friday morning with a smattering of light rain, snow and possible freezing rain near the immediate border with Upper Michigan. Ice and snow accumulations look minimal and sfc temps will be at or above freezing. Thus, impacts look to be on the lower side. Late tonight into Friday, the ongoing melting snow and warmer temps/dewpoints will support areas of fog developing over central and north-central WI. Fog could be locally dense. Given low temps remaining above freezing, roads that are now clear of recent snow cover should just stay wet. Friday will feature warmer temperatures as highs reach the 40s across the Fox Valley and lakeshore, with around 50 across central and north-central Wisconsin. A low pressure system developing over the Plains will bring a surge of warm air to the region on Saturday along with some small chances for rain across far north- central Wisconsin. This will likely be the warmest day in the next week as temperatures top out in the 50s across central Wisconsin with a 30-60% chance of hitting 60 degrees south of Highway 10. 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. Chance of precipitation is 30-50% with most of the precipitation occurring on Saturday night. Probability of >2" of snow for the 24 hr period ending Sunday evening is now around 20%, trending up slightly over last few NBM runs. High pressure will then provide dry weather to the area early next week. Temps 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 could bring a round of rain/snow later Wednesday into Thursday. Higher-end precip with this system would be 0.5 inch of QPF. Top end snowfall (90th percentile) is around 2-3", mainly near the Upper Michigan border. At this point, this clipper represents the most notable system next week. && .AVIATION...for 06Z TAF Issuance Issued at 1040 PM CDT Thu Mar 19 2026 A light wintry mix is possible from KIMT to KMNM to K2P2 through 08z. Otherwise, main concern for tonight will be the potential for confidence. Confidence is high that there will be areas of fog around, but confidence is low if the fog would become dense at times. Any lingering fog should burn off by 15-16z. Southerly winds are expected to veer to the west and then northwest overnight into Friday morning. A lake breeze boundary is anticipated at KGRB/KATW/KMTW late Friday afternoon. Areas of fog are expected again Friday night into Saturday morning, and could be dense at times. && .HYDROLOGY... Issued at 201 PM CDT Thu Mar 19 2026 As temperatures warm later into the weekend, 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 Friday, with more widespread ripening of snowpack up over the area on Saturday. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....JLA AVIATION.......Eckberg HYDROLOGY......JLA