FXUS63 KDTX 192227 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 627 PM EDT Tue Aug 19 2025 .KEY MESSAGES... - Seasonable temperatures and dry weather move in and hold Wednesday through Friday. && .AVIATION... Residual shallow convection/showers will continue to exit east of metro Detroit, with the risk of additional showers ending by TAF issuance. A cold frontal passage now advancing across Detroit will support shallow cool air advection during the night. Ample post frontal low level moisture will sustain a low stratus deck through the night. Available guidance along with observational trends suggest prevailing low end MVFR and IFR ceilings. The post frontal northerly gradient will sustain winds around 10 knots through the night and will hinder fog development. While it is possible that some patches of drizzle may develop, which would support some reductions in visibility, confidence is not high enough to include in the terminals. Continued dry air advection and diurnal heating/mixing will result in a steady improving trend in ceiling heights during the day Wednesday. For DTW/D21 Convection...Shallow convection (mainly showers) will exit the far southeastern portion of the D21 airspace around/shortly after TAF issuance. No convection will occur through the remainder of the TAF forecast period. THRESHOLD PROBABILITIES... * High for ceilings aob 5000 feet tonight and Wednesday. && .PREV DISCUSSION... Issued at 314 PM EDT Tue Aug 19 2025 DISCUSSION... Strong upper level anticyclonic wave break over the Canadian Prairie provinces combined with weak entrance region dynamics over Ontario/Quebec is resulting in the amplification and digging of a trough over the Great Lakes region today. The greatest area of the height falls and synoptic scale ascent has now been squeezed immediately south and east of the cwa. Will still have to work through an axis of showers and convergence that is now pushing into northern Metro Detroit. Radar data supports warm cloud/small droplet distribution in the showers. No thunderstorms are expected, but rainfall rates could prove to be surprisingly efficient the couple of hours. Model data the past 24 hours or so has steadily converged on a solution that is much drier for the evening hours. Will continue chance PoPs. The midlevel trough is forecasted to be progressive, opening the doors to differential geopotential height rises tonight. While the large scale upper level pattern supports blocking over the Southwest United States, tilting of the upper level ridge into the Great Lakes is anticipated. The net result will be a uniform expansion of surface high pressure into Southeast Michigan with the anticyclone then persisting through the early portion of Saturday. More comfortable weather is expected with highs generally in the lower 80s (around normal) with surface dewpoints in the 50/60s. The next chance of rainfall is expected to be late Saturday and Sunday. There has been a strong consensus amongst the global models in amplifying a large wavelength upper level low pressure system as it pushes east of he Rocky Mountains. Current forecast suggests daytime high temperatures in the low 70s Next Monday and Tuesday, approximately 8 to 10 degrees below normal. MARINE... Low pressure reaches western Lake Erie late this afternoon and continues to track east toward Lake Ontario tonight. Showers with embedded thunderstorms will wane in coverage through the evening while wind over Lake Huron backs from east to northeast, increasing to around 15 to 20 knots with gusts to 25 knots on Wednesday. Small Craft Advisories are in effect for all southern Lake Huron nearshore zones through Wednesday evening. High pressure builds in from the northern Great Lakes through Thursday causing northeast wind to become light. Wind then shifts to southwest on Friday ahead of the next cold front set to arrive on Saturday. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...Beach Hazards Statement from Wednesday morning through Wednesday evening for MIZ049-055-063. Lake Huron...Small Craft Advisory from 8 AM to 10 PM EDT Wednesday for LHZ421- 422-441>443. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ AVIATION.....SC DISCUSSION...CB MARINE.......TF You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.