839 FXUS63 KDTX 041650 AFDDTXArea Forecast Discussion National Weather Service Detroit/Pontiac MI 1250 PM EDT Sat Oct 4 2025
.KEY MESSAGES...
- Dry with near record warmth this weekend.
- The next chance of rain arrives late Monday into Tuesday.
- More seasonable temperatures the latter half of the week.
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.AVIATION...
Anti-cyclonic flow through nearly the entire column continues to support broad scale subsidence and the lack of organized cloud production. The near surface high center is anchored to the southeast of the region, which will open the door for some modest moisture advection into central Lower Michigan this afternoon. Thus far, diurnal cumulus has failed to initiate - however, expectations are for a cloud field to sprout with the near record warmth later this afternoon. An isolated shower is possible with any congestus patch that manages to gel - especially in vicinity of FNT or MBS. Otherwise, light southerly flow will persist through Sunday morning - then freshen toward midday as aggressive mixing occurs - and some diurnal cumulus develop.
For DTW/D21 Convection... Thunderstorms will not occur through the forecast period.
DTW THRESHOLD PROBABILITIES...
* None.
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.PREV DISCUSSION... Issued at 357 AM EDT Sat Oct 4 2025
DISCUSSION...
Clear skies are noted this morning stretching from Texas to the southern Great Lakes. A glancing shortwave perturbation has led to isolated convection over northern MI, but this will remain confined to the northern part of the state. Another dry and sunny start to the day thus expected for SE Michigan, although temperatures this morning are running about 10 degrees warmer than yesterday. Primary discussion point today is near daily record high temperatures, which will climb into the upper 80s this afternoon-evening. Anomalous ridging and warm column temperatures (T in the 90th-99th percentile in the sub-500mb layer) are driving this warm airmass on the larger scale, while well-mixed profiles and lean moisture influence afford little opportunity for underachievement.
Remnant mid-level stability provides enough of a capping inversion to prevent deep convection today. That said, nearly all models do generate a shallow (~5.0 kft) layer of instability at the top of the boundary layer that is leading to weak simulated reflectivity returns in the hi-res guidance. A stray, low impact shower cannot be ruled out this afternoon.
Meanwhile, a deep Pacific wave traverses from the Four Corners region toward the Plains Sunday. The wave takes on a negative tilt and at this point induces a surface low that is driven poleward by the parent wave. The Great Lakes reside between this low and the departing high pressure, which holds steadfast over the mid- Atlantic. The constricted pressure gradient leads to gusty southwest flow, especially toward the Saginaw Valley/Thumb where afternoon gusts approach 25-30 mph Sunday and Monday. The lead wave lifts well north of the Great Lakes, with its cold front gradually dragging eastward into the Great Lakes region. An active precipitation response is expected within the frontal zone, especially considering the deep layer of return flow that will be established at the this time. Rain begins Monday afternoon across the north and gradually expands south as the front slowly approaches the cwa.
The front will eventually be accelerated into SE Michigan Tuesday morning as a potent shortwave breaks away from the polar low. This initiates a more rapid height fall response, which will be coupled with right entrance region jet dynamics to support strong synoptic forcing with the fropa. Widespread rain is expected as a result, with ensemble 24-hour QPF statistics still calculating an interquartile range of 0.25-0.50" with upper 25th percentile values upwards of 1". Timing of the front seems to favor a morning to mid-day passage, ultimately limiting the amount of instability that can build into the warm sector. So for now, the setup looks to favor mostly showers with embedded thunder. Passage of the front signifies a significant cool down with H8 temperatures dropping toward 0 C and daytime highs settling into the low 60s. Overnight lows will also have a shot at dropping below 40 degrees Wednesday and Thursday.
MARINE...
A series of low pressure systems will travel from the northern Plains into the James Bay this weekend. While this will not result in any significant changes across the Great Lakes, this will strengthen the pressure gradient slightly, reinforcing southerly flow across Great Lakes with gust potential ranging between 15 to 20 knots, favored across Lake Huron.
Much bigger changes arrive Monday as a strong cold front sweeps across the Great Lakes. Prior the passage of the front, south flow wind speeds will increase tomorrow night, bringing gust potential up to 25 knots over Lake Huron. Intrusion of cooler air Tuesday will bring continuation of breezy conditions, but the exact magnitude of gust potential remains uncertain. Gusts up to 30 knots look possible at this time.
CLIMATE...
The record highs for Today (Saturday, October 4th).
Detroit: 89 Degrees (Set in 1951) Flint: 88 Degrees (Set in 1951) Saginaw: 87 Degrees (Set in 1967)
The record highs for Sunday, October 5th.
Detroit: 88 Degrees (Set in 1951) Flint: 88 Degrees (Set in 1922) Saginaw: 86 Degrees (Set in 2007)
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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.....Mann DISCUSSION...MV MARINE.......AM CLIMATE......MV
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NWS DTX Office Area Forecast Discussion