517 FXUS63 KDTX 111806 AFDDTXArea Forecast Discussion National Weather Service Detroit/Pontiac MI 206 PM EDT Thu Sep 11 2025
.KEY MESSAGES...
- Dry today and Friday with above normal high temperatures, but areas of fog appear likely tonight.
- Chance of showers and slight chance of thunderstorms Saturday.
- Warm and dry Sunday through Wednesday.
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.AVIATION...
High pressure over Ontario continues to dominate the region, bringing light winds at or below 6 knots and fair weather cumulus. The diurnal cumulus will dissipate this evening as we lose daytime heating. With another night of clear skies and strong radiational cooling, expect the potential for patchy fog. Did maintain the TEMPO IFR mentions of BR between 09Z-13Z Friday morning.
For DTW/D21 Convection... No thunderstorms throughout the period.
THRESHOLD PROBABILITIES...
* None.
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.PREV DISCUSSION... Issued at 312 AM EDT Thu Sep 11 2025
DISCUSSION...
The upper-level ridge axis over the Western Great Lakes will extend into the Central Great Lakes this evening, with 500 MB heights reaching 584 DAM and holding through Friday. This should ensure dry conditions with a modest warming in the low levels each day as 850 MB temperatures are expected to reach around 12 C Thursday, and then reach and slightly exceed 13 C on Friday. Thus, temperatures in the low to mid-80s seem reasonable on Friday (assuming morning fog burns off in a timely fashion).
A strong PV anomaly/upper level low is on track to move through Hudson Bay on Friday and into Quebec on Saturday. Southeastern Michigan will be on the western fringe of the large trough that will sink south through New England and eastern Great Lakes on Saturday. A tight baroclinic zone is setting up with compressional warming on the lee side of the Rockies ejecting northeast from the Central Plains. There is a chance for showers and possible thunderstorms on Saturday as a shortwave moves out of the northern Rockies and tracks through the region. However, the exact track, position, and amount of instability and steepness of mid level lapse rates remain in question. The NAM is one most aggressive solutions, with not a whole lot of support from other solutions. NBM pops is still indicating only a chance of precipitation.
The summer-like upper level ridge axis is still on track to move overhead for Sunday and Monday. 500 MB heights are projected to reach 590 DAM (supported by Euro ensembles), and center of the ridge may hold in place through mid week, leading to dry and warm conditions Sunday-Wednesday.
MARINE...
High pressure drifts from Ontario to New England today and tomorrow, ensuring dry and calm marine conditions to end the work week. Light NE winds gradually veer to the SW by Friday as the high departs. SW flow advects elevated portions of a warm front into the area Friday afternoon, introducing low end shower chances Friday night into Saturday although better rain chances stay over Lake Michigan. High pressure then builds back into Ontario early next week, complemented by ridging aloft, to continue the stretch of favorable marine weather.
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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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AVIATION.....JA DISCUSSION...SF MARINE.......MV
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NWS DTX Office Area Forecast Discussion