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Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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998 FXUS63 KDTX 141736 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 136 PM EDT Sat Sep 14 2024 .KEY MESSAGES... - Very warm and dry conditions prevail today through at least the middle of next week. - Fog development will be possible early each morning. && .AVIATION... High amplitude, long wavelength ridging will remain centered over the Great Lakes region throughout the period. Dry boundary layer conditions and a strong capping inversion centered at 5.5 kft agl will preclude low cloud today. Shallow ground fog will again be possible at daybreak Sunday due to favorable radiative cooling conditions. For DTW/D21 Convection... Thunderstorms are not in the forecast for the foreseeable future. DTW THRESHOLD PROBABILITIES... * None. && .PREV DISCUSSION... Issued at 333 AM EDT Sat Sep 14 2024 DISCUSSION... 500mb analysis shows the resident ridge centered over northern Lake Huron is steady at 591 dam this morning. The remnants of Francine have stalled over the lower Mississippi Valley and local impacts will be limited to just intervals of cirrus at times today. The ridge maintains a subsident and stable profile with sfc high pressure continuing to dominate local conditions. Little change to the thermal profile compared to yesterday offers a similar forecast today with highs in the lower to mid 80s with mostly sunny skies after patchy morning fog mixes out. Lofted wildfire smoke continues to gyre over the region within the anticyclone - this will remain well above the surface and pose little threat to air quality at the surface. Lows will settle back into the upper 50s to lower 60s overnight into Sunday morning with another round of patchy fog possible prior to daybreak. Nearly identical conditions on Sunday as the upper ridge eases southeast into the eastern Great Lakes. Slightly deeper mixing may boost temps by a degree or two. By Monday the ridge will flatten substantially but still hold on overhead as the remnants of Francine merge with a coastal low off the Carolinas. The composite upper low will attempt to progress north into the Ohio Valley through the midweek but will be working against a very weak flow pattern and an anomalously high geopotential height field over the eastern CONUS and Canada. A small sample of ensemble members within the GEFS and GEPS families continues to show some of the Atlantic moisture making it into the local area as showers by Wednesday and Thursday, but the majority of members continue to hold dry conditions. Even those that do precipitate generally only produce a few hundredths of an inch. Deep troughing becomes established over the western CONUS next week which maintains a longwave ridge over the eastern CONUS and Great Lakes even after the current rex block breaks down. This favors continued above normal warmth and dry conditions through the end of the 7 day forecast. Highs in the 80s and lows in the 50s/60s will continue to be the norm in this pattern. Beyond this period, CPC highlights SE MI within a 80-90% chance for above normal temps and 33-50% chance for below normal precip for the 6-10 day outlook. The week 2 (8-14 day) outlook also leans toward above normal temps and below normal precip. MARINE... Central Great Lakes holds under the influence of high pressure through the first half of next week. This maintains dry conditions and generally light flow across the region though some gusts near 20kts will be possible over Lake Erie as the remnants of Francine tighten the gradient over the Ohio Valley and far southern Great Lakes. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ AVIATION.....CB DISCUSSION...TF MARINE.......KDK You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.