Area Forecast Discussion
Issued by NWS Green Bay, WI
Issued by NWS Green Bay, WI
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792 FXUS63 KGRB 162317 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 617 PM CDT Mon Sep 16 2024 Updated aviation portion for 00Z TAF issuance .KEY MESSAGES... - Summer-like temperatures continue through Thursday with highs in the 80s. Temperatures to stay in the 70s near Lake Michigan. Slightly cooler temperatures are expected this weekend. - Other than a small chance (15 to 20%) of a thunderstorm over far north-central WI through this evening, the next chances for rain arrive late this week and carry into the weekend. && .DISCUSSION... Issued at 158 PM CDT Mon Sep 16 2024 Short Term...Tonight and Tuesday Isolated instability showers and storms have developed within a pocket of higher MLCAPEs values (1000-1500 J/kg) across northwest and far north-central WI this afternoon. With weak vertical wind profiles expect storms to be pulsy in nature with little to no severe weather threat. As evidenced by the lack of cumulus cloud development, a more stable air mass is in place south of a Wausau to Marinette line. This portion of the CWA should remain dry through this afternoon. Temperates across the region are once again well above normal, with readings as of 2pm ranging from the lower to upper 80s across the region. Tonight...Instability showers that developed this afternoon across north-central WI should diminish this evening with dry conditions expected overnight. Scatted cloud cover across northern WI will lead to slower cooler temperatures tonight resulting in lows in the middle to upper 50s at most locations overnight. Light onshore flow may lead to the development of patchy fog near the lakeshore early Tuesday morning. Tuesday...Dry conditions across the area are expected to remain through Tuesday as a 500mb ridge and dry mid-level air mass continue to sit over the region. Skies will be a mix of sun and clouds as middle and high clouds generated by a trough digging over the Rockies filter over the area. The combination of sun and light southerly winds will allow for another day of well above normal temperatues. Highs across most of the region are forecast to reach the low to middle 80s, while onshore flow will keep lakeshore areas about 5 degrees cooler. Long Term...Tuesday Night Through Monday An omega blocking pattern will remain across the CONUS this week, with the ridge portion of the pattern across the Great Lakes region. This will keep the weather dry through much of the week as temperatures remain well above normal for this time of year. The pattern will shift a bit east towards the end of the week into the weekend, which will allow the troughs and subsequent army of PV anomalies to make headway over the western Great Lakes region. The first one looks to arrive Thursday night into Friday, which will bring a good chance for rain (40-60 percent) to central and north-central Wisconsin and lesser chances (20-30 percent) further east closer to the influence of the high. The low pressure systems tracking through the region this upcoming weekend and into early next week are a bit more murky as the long-range models differ on the influence the ridge will have across the area. The stronger ridging in place would portend a drier solution, while a more progressive trend would make for a wetter weekend. Once a ridge is in place it can be difficult to unseat; therefore, would bet on at least some dry periods this weekend with the possibility for rain showers/thunderstorms at times if the shortwaves can make it this far east. Despite the pattern that eventually emerges, there continues to be consensus on continued well above normal temperatures into at least the weekend. In addition to the warm temperatures, some ground fog will continue to be possible at times as a moist atmosphere will be in place across the western Great Lakes region on southerly flow. && .AVIATION...for 00Z TAF Issuance Issued at 617 PM CDT Mon Sep 16 2024 An upper level disturbance will produce high clouds as it moves across Wisconsin tonight. There is a slight chance that some ground fog could form late tonight west of the bay and Lake Michigan at OCQ and MTW. Otherwise VFR conditions are likely across the area overnight. VFR conditions will continue Tuesday, with some high clouds at times and light surface winds from the south. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....GK/Kurimski AVIATION.......RDM