Area Forecast Discussion
Issued by NWS Green Bay, WI
Issued by NWS Green Bay, WI
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734 FXUS63 KGRB 252310 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 610 PM CDT Wed Sep 25 2024 Updated aviation portion for 00Z TAF issuance .KEY MESSAGES... - Widespread patchy fog, some locally dense, may impact the Thursday morning commute. - Warm temperatures to prevail through the end of the work week, with highs running between 10 to 15 degrees above average. - Expect a mostly dry weekend as residual moisture from Helene is shunted to our south and east. Next chances for precip then arrive Monday afternoon. && .DISCUSSION... Issued at 245 PM CDT Wed Sep 25 2024 Short Term...Tonight and Thursday Relatively quiet conditions are expected for the rest of the afternoon and evening, as mid-level clouds associated with a passing upper trough axis depart the region. Fog will be the main weather concern overnight, as conditions for fog formation appear more favorable than last night. Therefore, would expect areas of fog and some patchy dense fog, especially in areas of central to north-central Wisconsin, west of the Fox Valley. Low temperatures will be a couple degrees warmer than last night, but still generally range from the middle 40s to the middle 50s. Thursday will bring back sunny conditions, which will help mix out the fog fairly quickly in the morning. The rest of the day is expected to be fairly quiet and mild, with high temperatures getting back into upper 70s to lower 80s. Long Term...Thursday Night Through Wednesday Model guidance has been trending toward a drier forecast for the extended as remnant moisture from Hurricane Helene gets locked up in the Ohio River Valley over the weekend. Additionally, cold frontal passage Sunday into Monday looks to be mostly dry as models show any moisture out ahead of the front being trapped to our north. Precip chances... Expect warm and dry conditions to prevail through the weekend as a rex blocking pattern maintains ridging over the upper Midwest. As upper-level flow flattens out toward the end of the week, ensembles show Helene becoming a post-tropical cyclone as it makes landfall over Florida and travels north along the Eastern Seaboard. Not currently expecting much, if anything, in terms of precip as dry continental air shunts any remaining moisture from Helene off to our south and east. Next chances for rain/storms then arrive Monday afternoon as robust troughing spins up Canadian low pressure over Alberta. Not too impressed with precip chances during this time as well given an abundance of dry air and limited instability. This being said, a rumble of thunder cannot be ruled out from central to north-central Wisconsin Monday afternoon given sufficient mid-level lapse rates (~6.5 to 7 C/km). Well below average precip over the past month paired with a strong signal for more dry weather to come has resulted in moderate drought conditions being introduced across northeast Wisconsin. If the current pattern continues, drought conditions are predicted to expand across the forecast area. Temperatures... Anomalously warm 850 mb temperatures (~14 to 16C) and subsidence from high pressure will result in the brief return of summer-like temperatures through the end of the week. Saturday looks to be the warmest day, with highs ranging from the mid to upper 70s. Some locations across central Wisconsin may even see 80 before the week is over. Only caveat will be whether or not the cirrus shield from Helene causes temperatures to underperform. Post-frontal temperatures will then drop down into the mid 50s to mid 60s on Tuesday, reading near to slightly below average for late September. && .AVIATION...for 00Z TAF Issuance Issued at 610 PM CDT Wed Sep 25 2024 Scattered cloud cover around 5000 feet will dissipate this evening with the loss of daytime heating. Ground fog will be the main concern for tonight, as cooler temperatures and clear skies allow fairly widespread fog. The best chance for fog will be across north-central Wisconsin and near the Lake Michigan shoreline, so the lowest visibility forecast was included for these areas. The fog should mix out a few hours after sunrise, with good visibility and flying conditions expected the rest of the day on Thursday. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....Uhlmann/Goodin AVIATION.......Kurimski