FXUS63 KGRB 152338 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 638 PM CDT Wed Apr 15 2026 Updated aviation portion for 00Z TAF issuance .KEY MESSAGES... - Another round of rain/storm arrives from the south later this afternoon and evening. One inch hail would be the main hazard with any stronger storms. - Additional rainfall will continue to exacerbate ongoing areal flooding. Flash flooding would be possible in areas that have already received multiple inches of rainfall, or over areas that see training storms. - Minor to moderate flooding is ongoing or forecast to occur on several rivers. Expect many rivers to continue rising this week, with the greatest impacts expected on the Menominee River where major flooding has been observed. - Widespread rain/storms will again be possible on Friday. Some storms could become strong or severe. && .DISCUSSION... Issued at 143 PM CDT Wed Apr 15 2026 Rain/storm chances today... Frontal boundary remains stalled out over southern Wisconsin as of early this afternoon, which will bring our next chances for rain and storms later this afternoon into this evening. Par for the course, the main concern will be how any additional rainfall will exacerbate ongoing flooding, especially in areas that are already vulnerable. Overall, we're looking at receiving an additional 0.25 to 0.5" of QPF through tonight, with probabilistic guidance showing a 30 to 50% signal for 0.5" of rain over the southern Fox Valley. Reasonable high- end scenario (90 to 95th percentile) would bring amounts in excess of one inch from the Fox Valley to the lakeshore, though this would most likely occur with a slight northward shift of the boundary and training storms. If these amounts were to be realized, flash flood thresholds would likely be met over east- central Wisconsin where soils are already saturated and areal flooding is ongoing. Severe threat for this afternoon looks less distinguished than yesterday given unfavorable placement north of the front and stable easterly boundary layer flow. Elevated instability (300 to 500 J/kg MUCAPE) and appreciable deep-layer shear (50+ knots) sneak into our southern tier of counties late this afternoon, though the threat for any surface-based storms is low. Cannot rule out the possibility for an elevated hailer or two given elongated hodographs and decent lapse rates, though suspect that severe potential would be rather limited. Strong/severe storms late week... Following a brief lull in precip Thursday into Friday, 500 mb pattern then re-amplifies toward the end of the week. Robust trough approaches from the Intermountain West on Saturday as a deepening surface low ejects from the central Plains, bringing with them yet more chances for widespread heavy rain and strong or severe storms. Southerly flow regime would support decent moisture transport from an open Gulf, with a narrow corridor of 60 dewpoints possible along the leading edge of cold FROPA. Decent instability (~1,000 J/kg CAPE) would favor linear ascent along the front, resulting in likely upscale development into a QLCS storm mode Friday evening and overnight. Main source of uncertainty at this time centers around timing of the front, which currently looks to be late Friday night into early Saturday morning. Regardless, this system looks to be much more dynamic than what we've seen this week thus far, especially with the influence of a 50+ knot LLJ and favorable deep layer shear. Given an ample supply of Gulf moisture, heavy rain once again becomes a concern Friday into Saturday. Probabilistic guidance currently shows a widespread 30 to 50% chance for receiving 1 inch of rain, with a signal (10 to 30% chance) for exceeding 1.5". Locally higher amounts would be possible within convection. As such, flash flood potential would once again come into play Friday into Saturday, where WPC currently highlights most of the state in a marginal Day 4 risk for excessive rainfall. Muc colder air wraps in from the northwest on the back end of the departing surface low on Saturday, resulting in a probable transition from rain to snow across the far north. Probabilities for half an inch of snow currently stand at 20 to 40% mainly over Vilas, so little to no impacts are expected. Temperatures then drop off steeply by Saturday afternoon, bringing highs down into the 30s and 40s for most. High pressure then settles in over the CONUS late this weekend and into early next week, affording us a much needed dry spell. && .AVIATION...for 00Z TAF Issuance Issued at 638 PM CDT Wed Apr 15 2026 Conditions have improved to VFR across north-central and portions of central Wisconsin early this evening with MVFR/IFR stratus across east-central Wisconsin and the lakeshore. An area of showers and thunderstorms still look on track to affect mainly the east-central Wisconsin TAF sites this evening, with only light rain in the next few hours across the central Wisconsin TAF sites while north-central Wisconsin remains mostly dry. Light rain will linger across the east through the overnight hours. A strong hail-producing storm or two cannot be ruled out during this time; however, severe potential should be limited. Conditions could drop to IFR/LIFR with any heavier rain. Light winds and recent rainfall may result in areas of fog/low stratus development late tonight into early Thursday morning. Locally dense fog with vsbys below 1SM will be possible, though was not confident enough to provide timing resolution as of yet. Conditions then improve to VFR on Thursday from west to east as skies clear across the region. && .HYDROLOGY... Issued at 143 PM CDT Wed Apr 15 2026 Following another bout of heavy rain and storms yesterday, widespread flooding continues across portions of central to east- central Wisconsin where an areal Flood Warning remains in effect. Several roads remain closed, especially in areas that received between 3 and 6 inches of convectively-enhanced precip over the past 48 hours. Multiple rivers, namely the Wolf, Menominee, and Wisconsin Rivers, continue to read in minor to moderate flood stage, with the Menominee River now in major flood stage due to the additional influence of snow melt from the Upper Peninsula. Home evacuations are ongoing along the Wolf River. High flows and rising water levels have also resulted in several dams being compromised or overtopped. If you live near a river or stream, continue to monitor the latest hydro forecasts and Flood Warnings from the National Weather Service in Green Bay. && .GRB WATCHES/WARNINGS/ADVISORIES... Dense Fog Advisory from 11 PM this evening to 10 AM CDT Thursday for WIZ005-010>013-018>022-030-031-035>040-045-048>050-073-074. Flood Watch through Thursday morning for WIZ031-037>040-045- 048>050-074. && $$ DISCUSSION.....Goodin AVIATION.......Kurimski HYDROLOGY......Goodin