


Area Forecast Discussion
Issued by NWS Green Bay, WI
Issued by NWS Green Bay, WI
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059 FXUS63 KGRB 171844 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 144 PM CDT Fri Oct 17 2025 Forecast discussion for routine afternoon forecast issuance .KEY MESSAGES... - Warm through Saturday, with highs in the upper 60s to middle 70s. Temperatures return back to normal beginning Sunday. - Periodic showers and a few thunderstorms late this afternoon and tonight, then again Saturday night into Sunday morning. - Breezy this afternoon with southerly gusts to 25 mph, and again on Sunday as northwest winds gust to 25 to 35 mph. && .DISCUSSION... Issued at 138 PM CDT Fri Oct 17 2025 Strong 990-995mb low pressure tied to negative tilted mid-level trough lifting across Manitoba is pushing a weak cold front (more so a wind shift) into western WI. A broken line of light showers were along the front earlier, though they have pretty much dissipated now. It is breezy and warm over northeast WI ahead of the front. Under partly sunny skies, early afternoon temperatures have already reached the low to mid 70s. Normal highs are in the mid to upper 50s. As instability (SBCAPE) increases into early this evening to 200-400J/kg, showers as close as central IA will expand as they push into central and north-central WI. Even with the projected meager instability, given stronger 500mb and 850mb jets over the area, effective shear and helicity increase enough that an isolated strong storm or two cannot be ruled out late this afternoon into early this evening over central WI. 12z HREF 40+ dbz paintballs hint at this as well. Later tonight, showers will diminish in coverage as they reach eastern WI. Rainfall amounts by daybreak Saturday will mainly be less than one-quarter inch at any location, though locations that see any storms will have a better chance to exceed that. Rain exits to our east early on Saturday. Most areas stay dry on Saturday and still relatively mild as readings over eastern WI could reach the lower, maybe even mid 70s. Stronger cold front arrives Saturday afternoon through Saturday night as a potent negatively tilted trough crosses the upper Mississippi river valley and Great Lakes. Further, as southern stream shortwave trough over the desert southwest today, phases with the primary trough, cyclogenesis will occur with closed off sfc low Saturday night over Ill and shifting to vcnty of northern Ill/southwest MI by Sunday morning. Trend of the sfc low is still farther east than what was shown a couple days ago, though most recent model runs have not went any farther east. Moderate to heavy rain will occur along and just west of the low, which at this point continues to set up over Lake Michigan and into western Michigan. Light to moderate rain will still impact eastern WI late Saturday night through Sunday morning. Even so, chances of seeing more than 0.50 inch in eastern WI remain less than 20%. With the farther east trend of the low, probability of gale force gusts over 35kt/40 mph are more focused farther into the lake away from the shore. It will still be breezy though as gusts over the land areas should still reach 25 to 30 mph on Sunday. Rain still on track to taper off by Sunday afternoon, with dry weather lasting through Monday morning. The break in rain is brief though as another strong shortwave trough and sfc low dig across the northern Great Lakes on Monday night into Tuesday. Warm air advection will help develop showers on Monday afternoon, with more showers possible in the stronger cold moist advection regime behind the system on Tuesday. Tuesday will be blustery with highs barely reaching 50 over eastern WI and staying stuck in the 40s elsewhere. Rest of the week features small chances for showers, before pattern becomes less active late in the week. Temperatures will remain around normal for highs, with low temperatures around freezing farther inland and into the mid to upper 30s over eastern WI. Depending on whether winds can go calm, there will be a potential for frost. && .AVIATION...for 18Z TAF Issuance Issued at 1220 PM CDT Fri Oct 17 2025 A weak cold front, with a slight wind shift from S to SW winds, results in scattered showers this afternoon into tonight as it moves through. Enough instability for embedded thunder. Greatest coverage of showers and best chance for any thunderstorms will be over central to north-central WI late this afternoon through this evening, where a mention for TSRA was retained. Greatest chances for showers in eastern WI holds off until overnight. These showers will end around daybreak on Saturday. Winds will be from the south and gusty through late afternoon. Weakening sfc winds with low-level jet overhead will result in another round of LLWS this evening into the early overnight hours. Even with the showers, conditions will be mainly VFR as the front moves through through. Partial clearing behind the front may result in low clouds and patchy fog developing central to north- central WI 09z-14z. Expect VFR conditions to then prevail region- wide through Saturday afternoon with a few fair weather cu and scattered mid and high clouds. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....JLA AVIATION.......JLA