FXUS63 KDTX 191914 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 314 PM EDT Tue Aug 19 2025 .KEY MESSAGES... - Seasonable temperatures and dry weather move in and hold Wednesday through Friday. && .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 suprisingly 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. && .PREV DISCUSSION... Issued at 138 PM EDT Tue Aug 19 2025 AVIATION... Low pressure now centered over SE MI will continue to progress east into southern Lake Huron and Ontario late tonight and overnight. Copious low level moisture has reinforced IFR cigs and spotty showers leading into the afternoon hours. While some minor improvements to ceiling heights into mvfr will be possible in the afternoon with daytime heating, most favorable for the Metro terminals, the expectation is that wrap around moisture from the departing low in conjunction with lake enhanced moisture will reinforce IFR cigs late tonight and overnight. Some periods of LIFR cannot be ruled out overnight, most favorable across KPTK to KFNT with the higher terrain. Additionally, some spotty showers will be possible through the afternoon. A strengthening low level inversion will maintain low lying stratus leading into the early afternoon hours tomorrow. Otherwise, passage of the low will rapidly change wind direction from southwest to northwest through the afternoon and early evening hours. For DTW/D21 Convection...There will be a 10% chance for an isolated thunderstorm through 22Z. But overall, thunderstorm chances have been trending downwards given the copious cloud cover and lack of instability. Have removed mentions of thunderstorms given the low- end probabilities. THRESHOLD PROBABILITIES... * High for ceilings aob 5000 feet through the TAF period. * Low for thunderstorms through 22Z. && .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. && $$ DISCUSSION...CB MARINE.......TF AVIATION.....AM You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.