856 FXUS63 KDTX 090350 AFDDTXArea Forecast Discussion National Weather Service Detroit/Pontiac MI 1150 PM EDT Wed Oct 8 2025
.KEY MESSAGES...
- Frost Advisory in effect Midnight tonight until 9am Thursday for much of Southeast Michigan outside of the Detroit urban heat island.
- Potential for frost Friday morning as temperatures fall into the mid to upper 30s.
- Unsettled conditions possible this weekend as low pressure moves into the Great Lakes.
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.AVIATION...
High pressure will maintain control this period, ensuring VFR conditions within a very dry environment. Light northeast flow will draw some moisture off lake Huron into the region overnight, which may afford some brief intervals of lower VFR, particularly near MBS. Otherwise, limited cloud production through Thursday given the magnitude of the ambient dry layer. Winds remain modest from an easterly direction during the daylight period. Some degree of moisture flux off lake Erie may lead to some expansion of lower cloud Thursday night.
For DTW/D21 Convection...No convection will occur through the TAF period.
DTW THRESHOLD PROBABILITIES...
* None
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.PREV DISCUSSION... Issued at 349 PM EDT Wed Oct 8 2025
DISCUSSION...
Prototypical, cool, Autumn conditions are in place this afternoon with polar high pressure building into the Great Lakes regions from the northwest. Differential cold advection in the lower troposphere has resulted in strong midlevel static stability with nothing more than flat, low coverage diurnal cumulus. Favorable radiative cooling conditions will develop for many locations with clear skies and calm winds. The exception will be those areas immediately downwind of Lake Huron. Multiple guidance sources suggest a light easterly wind direction holding on throughout the night. This would result in a warmer wind off of the water in addition to the advection of some lake cloud. Based off of NBM-CONUS data and the probabilities for temperatures of less than 37 degrees, went ahead and decided for Frost Advisories for all counties in Southeast Michigan except Wayne County (NBM probabilities of less than 37 is at 8% for much of the county, 13% Northville to Plymouth). Off of a cold start, highs Thursday are forecasted to be around 60 degrees, some 5 degrees below average.
Consensus of operational runs, including the 08.12Z control run of the ECMWF, directs a vigorous shortwave southeastward into the Great Lakes Friday. The overwhelming consensus then predicts the closed low circulation to stall out overhead as a blocking ridge rapidly organizes off the East Coast and through Quebec. Latest European ensemble data with EC-AIFS keeps the precipitation footprint relatively progressive carrying light QPF amounts eastward into Canada by midday Saturday. The latest forecast has chance PoPs Friday evening through Saturday evening which appears reasonable. Best proxy for precipitation chances across the area will be when 500mb temperatures crash into the -20 to -23C range. However, slower timing and a very dry subcloud layer in advance of the system could limit coverage. Important to note that Control run of the ECMWF is running significantly wetter than the ensemble data. For DTW, the interquartile range for 24 hour QPF amounts at 12Z Sunday is between 0.1 and 0.4 of an inch.
Aggressive surface ridging is forecasted to build back into Southeast Michigan for the beginning of next week. Pleasant weather with temperatures some 5 degree above normal.
MARINE...
High pressure drifts directly over the central Great Lakes this evening-tonight resulting in a steady reduction in wind speeds and subsequent waves going into Thursday. Southwesterly winds then increase Thursday night as high pressure shifts towards the Northeast ahead of low pressure dropping out of northern Canada. Said low looks to slowly track over the Great Lakes this weekend bringing renewed shower and waterspout chances however winds remain more modest, generally between 15-25kts.
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.DTX WATCHES/WARNINGS/ADVISORIES... MI...Frost Advisory until 9 AM EDT Thursday for MIZ047>049-053>055- 060>063-068>070-075-082-083.
Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. &&
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AVIATION.....MR DISCUSSION...CB MARINE.......KDK
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NWS DTX Office Area Forecast Discussion