Area Forecast Discussion
Issued by NWS Green Bay, WI
Issued by NWS Green Bay, WI
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967 FXUS63 KGRB 172325 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 625 PM CDT Tue Sep 17 2024 Updated aviation portion for 00Z TAF issuance .KEY MESSAGES... - Near-record high temperatures expected to continue for Wednesday and Thursday. - Showers and non-severe thunderstorms are expected (60 to 80% chance) in central WI on Thursday night/Friday morning. - A pattern shift is expected Friday into this weekend, with highs dropping down into the 70s, and increased rain chances every few days. && .DISCUSSION... Issued at 251 PM CDT Tue Sep 17 2024 Confidence is high that the weather for tonight, tomorrow, and Thursday will remain very similar to the past few days. Above-normal temperatures are expected, with highs in the 80s and lows in the 60s. Dewpoint temperatures are forecast to be in the 50s, so no hazardous heat index values are expected... though worth noting that our forecast area remains in the "yellow" category for the HeatRisk... which indicates a "Minor" level of heat-induced impacts. A "Minor" HeatRisk level can especially impact those outdoors without effective cooling and/or adequate hydration. Heading into Thursday night and beyond, a change in our overall weather pattern will occur... For Thursday PM, we will be keeping an eye on a trough axis that extends north-south from Canada through Minnesota and is expected to help generate strong to potentially severe thunderstorms over Minnesota during the peak heating hours on Thursday. This boundary is expected to move eastward into Wisconsin, arriving near central Wisconsin around the midnight hour. The key thing for our area is that as the sun goes down, the intensity of this precipitation will also diminish. At this time, severe weather is not forecast in our area for Thursday/Thursday night, and lightning will be the primary hazard. At this time, rainfall chances in central WI are around 80% for Thursday night, and around 50% across the Fox Valley. With the weakening system, forecast rainfall is in the 0.10" to 0.25" range. For Friday PM, this system will generally be centered around the Fox Valley region into Lake Michigan. As with this system on Thursday, peak daytime heating hours are when this system will be its most intense. Still time for the location/timing to change, but as of now, it appears the key ingredients for strong/severe weather will be located more over Lake Michigan. Aloft, the forecast wind profile is not very strong, with 850mb winds slated to weaken to the 15kt range. So along with a slight change of thunder (25%), we could see a brief wind gust of around 20 to 25 mph mix down to the surface. The passing of this boundary helps unveil the curtain for the overall weather pattern change heading into next week. Long-range forecast models are hinting at us transitioning into an overall weather pattern of a quick-moving system to bring showers and a few rumbles of thunder every few days. There is not yet any notable "arctic" air embedded in this pattern, so am expecting above normal temperatures to continue... however, with the clouds and showers, am expecting the magnitude of the above normal temperatures to be much lower than they have been the past few days. Instead of near-record high in the mid to upper 80s, would expect temperatures to be closer to the mid to upper 70s range... still above-normal, but 5 to 10 degrees above normal as opposed to 15 to 20 degrees above normal. && .AVIATION...for 00Z TAF Issuance Issued at 624 PM CDT Tue Sep 17 2024 Good flying weather is expected tonight through at least Thursday morning, with the possible exception of ground fog for around ten miles inland from Lake Michigan and the bay (MTW, OCQ, and possibly SUE and MNM)b etween 08z and 13z each morning. There will be periods of high clouds, but otherwise skies will be generally clear. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....Kotenberg AVIATION.......RDM