227 FXUS63 KDTX 161945 AFDDTXArea Forecast Discussion National Weather Service Detroit/Pontiac MI 345 PM EDT Tue Sep 16 2025
.KEY MESSAGES...
- Above normal high temperatures continue into the weekend.
- Dry weather through the first half of the weekend.
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.DISCUSSION...
Pseudo omega block pattern maintains stagnant conditions as a 590 dam (+1.5 sigma) 500mb ridge remains parked over the Great Lakes between a coastal low in the Mid-Atlantic and a cutoff upper low over Wyoming. Surface high pressure centered across the Great Lakes into the Canadian Maritimes dominates local conditions tonight into Wednesday before the coastal low weakens and releases up the coast. Dry and warm weather this evening gives way to another night of strong radiational cooling with lows dipping into the 50s. Prevailing east to northeast flow off the lakes will send the marine layer inland this evening, setting the stage for another round of fog development overnight. Some locations may see a period of dense fog early Wednesday with any fog then mixing out through mid morning.
Persistence forecast on Wednesday with the ridge maintaining highly stable conditions across the area. Another day of full sun sends highs back into the lower to mid 80s. The ridge then begins to break down Wednesday night as a northern stream waves tracks across Ontario. This wave will send a backdoor cold front across the area on Thursday. Low-level flow, albeit weak, shifts southwest Wednesday night ahead of the front which should lower fog prospects Thursday morning. A ridge of theta-e pools in ahead of the front resulting in a corridor of destabilization Thursday afternoon - this may be sufficient for a few showers. Support for ascent will be weak as the upper wave passes off to the east with displaced upper jet forcing. Any showers would be light and do nothing to alleviate the developing drought conditions. Temperatures in the far south may make a run at the upper 80s while areas to the north hold in the lower to mid 80s as the front brings in more clouds during peak heating.
The front settles south of the area on Friday as high pressure spreads across northern Ontario. Slightly cooler air arrives but highs are still progged to hold on the warm side of normal in the 70s and lower 80s. The next mid-level ridge crests over the area late in the week as troughing slowly meanders across the northern Plains. After the axis passes overhead around Friday, a higher degree of warmth spreads back into the area with high temps back into the 80s likely this weekend. The trough migrates into the region Monday into Tuesday providing the next opportunity for rain showers.
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.MARINE...
A ridge of high pressure continues to bring an extended period of dry weather and lighter winds to the Great Lakes through most of the week. Winds continue to favor a light easterly component, with some gradual backing to the south and then north late tomorrow into Wednesday. A secondary high pressure system is expected to drop from the central Canadian provinces into Ontario and Quebec late this week, which will strengthen the pressure gradient over the Great Lakes region. This will again reinforce northeasterly to east flow and will bring some elevated wind speeds for Lake Huron where sustained winds nearing 20 knots and gust potential to 25 knots will be possible.
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.PREV DISCUSSION... Issued at 135 PM EDT Tue Sep 16 2025
AVIATION...
Standard high pressure configuration today promotes ENE winds and limited clouds. VFR conditions prevail through the rest of today and most of tonight with winds trending toward calm. Expect pockets of renewed fog development late tonight into Wednesday morning which could produce periods of MVFR to IFR visibility reductions. Might also see some low status duct in off the central Lakes which may lead to IFR (or LIFR) restrictions. Otherwise, the dry pattern persists on Wednesday with slightly more cohesive flow organizing out of the north and FEW-SCT high-based cumulus.
For DTW/D21 Convection...No thunderstorms expected through the TAF period.
THRESHOLD PROBABILITIES...
* Low for ceilings at or below 200 feet between 09Z and 13Z Wednesday.
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.DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. &&
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DISCUSSION...TF MARINE.......AM AVIATION.....KGK
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NWS DTX Office Area Forecast Discussion