Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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119 FXUS63 KDTX 170347 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 1147 PM EDT Mon Sep 16 2024 .KEY MESSAGES... - Seasonably warm and mainly dry conditions prevail through the workweek and most of the weekend. - Patchy morning fog develops Tuesday morning followed by increasing cloud cover Tuesday night and Wednesday. && .AVIATION... Expansive area of high pressure maintains influence this period. This ensures dry and stable conditions, precluding lower cloud development. Shallow ground fog will again be possible at daybreak Tuesday due to favorable radiative cooling conditions. Light winds generally from the southeast persist. For DTW/D21 Convection... Thunderstorms are not in the forecast for the foreseeable future. DTW THRESHOLD PROBABILITIES... * None. && .PREV DISCUSSION... Issued at 300 PM EDT Mon Sep 16 2024 DISCUSSION... Extended stretch of mild and dry weather continues for at least the next 48 hours as the longwave pattern remains blocked by a protruding 590 dam ridge encompassing the Great Lakes/Northeast while upper lows over the Lower Mississippi Valley and The Carolinas interact over the south. Thermodynamic profiles have been largely unchanged from day to day marked by H8 temps in the low-mid teens and surface dewpoints in the upper 50s to around 60s. Deep-layer subsidence continues to offer mainly clear skies while the lowest dewpoint depression through the column is found near the top of the boundary-layer. With the exception of perhaps a few shallow diurnal cumulus clouds today/tomorrow and lingering/trapped wildfire smoke well above the surface, low aerosol optical depths support largely unencumbered insolation lending highs of 5-10F above normal today and Tuesday. More typical nocturnal readings arise both nights with broad radiational cooling window. See no reason to veer from previously included patchy fog mention around sunrise Tuesday. Primary forecast consideration for this week maintains focus on a (sub-)tropical cyclone that is now tracking west across The Carolinas with improving vertical continuity through the troposphere. This system fully closes off tonight and remains positioned downstream of more meaningful steering dynamics which are revolving around western CONUS. Underwhelming split-flow configuration aloft allows the aforementioned low to drift northwest across southern Appalachia and toward the Ohio Valley with little resistance. Latest guidance shows reduced variance in the northwest extent of the system as a more rapid collapse unfolds Tuesday night and Wednesday morning lending higher confidence in locally dry conditions through the end of the work week, and potentially through the weekend. For context, the official Detroit Area rainfall total for this month stands at 0.06 inches, all of which fell on September 6th. If the dry forecast holds, it would mark the driest recorded September (through the 22nd) since 1908. MARINE... Sprawling high pressure continues to govern conditions for the central Great Lakes through the forecast period offering mainly dry weather and light southeast winds (AOB 15 knots). A (sub-)tropical cyclone that is now tracking west across The Carolinas fully closes off tonight but remains positioned downstream of the more meaningful steering dynamics over western CONUS. Latest guidance shows a rapid collapse unfolding Tuesday night and Wednesday morning over the Ohio Valley keeping the resident ridge of high pressure in control through the workweek. This ensures persistent light easterly composed flow yielding favorable marine conditions into the weekend. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ AVIATION.....MR DISCUSSION...KGK MARINE.......KGK You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.