993 FXUS63 KDTX 091014 AFDDTXArea Forecast Discussion National Weather Service Detroit/Pontiac MI 614 AM EDT Thu Oct 9 2025
.KEY MESSAGES...
- Frost Advisory remains in effect through 9am 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...
The center of high pressure just north of Lake Huron will drift to eastern Ontario today, sustaining a light easterly wind across Se Mi. While strong subsidence will continue to foster mainly clear skies, there have been some intervals of clouds tracking across the area due to the moisture flux off the lakes. Considering the degree of dry air, any strato cu off Lakes Huron/Erie should remain FEW to SCT. Bases will be VFR although lowering of the inversion through subsidence may lead to a few MVFR based clouds tonight.
For DTW/D21 Convection...No convection will occur through the TAF period.
DTW THRESHOLD PROBABILITIES...
* None
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.PREV DISCUSSION... Issued at 352 AM EDT Thu Oct 9 2025
DISCUSSION...
A chilly start to the day across southern Lower Michigan, with most locations reporting temperatures in the mid 30s under clear skies and light northeast winds. A Frost Advisory remains in effect through 9am as a result. Localized warmer temperatures are observed downwind of Saginaw Bay where stratus has moved inland and disrupted the radiative cooling process.
Remainder of the day will feel very similar to yesterday with high temperatures just barely reaching 60 degrees under plenty of early October sunshine and thermal troughing. The 00z KDTX RAOB sampled 850mb temperatures right at 0 C, marking a ~15 C drop in h8 temperature over the past 48 hours. Main difference between today and yesterday is the departure of the surface high, which contributes to veering wind profiles toward the east-southeast. Not expecting lake cloud to push as far inland today given the shifting winds/shorter fetch, but there is potential for Lake Erie moisture to get drawn into the Detroit Metro region tonight. Any cloud cover will again inhibit radiative cooling, but cloud-free areas see lows in the mid 30s making Friday morning another candidate for frost headlines.
Low amplitude ridging holds in place for the majority of today, but quickly breaks down overnight as a northern stream PV anomaly cuts off and dives equatorward toward the Great Lakes Friday. Mid-level heights fall in response with a shift to southwest flow in the low levels to kickstart warm advection. This brings daytime highs into the mid-upper 60s and increasing clouds ahead of a cold front that dives across the area Friday evening. The fropa will struggle to generate much QPF given shallow moisture depths, modest forcing, and a very dry sub-cloud layer.
A much stronger synoptic response arrives overnight Friday as the compact vort max moves into the Great Lakes. Models still exhibit large variance in the track of the upper low, ranging anywhere from Lake Michigan to Ontario. Most solutions support measurable QPF across SE Michigan, but rainfall amounts will be closely tied to our position wrt the low. The less likely scenario is one that favors a western track (i.e. 00z NAM) where SE Michigan is upstream of the circulation in a region of strengthening moist isentropic ascent as the low occludes. This is represented in a handful of models/ensemble members, and would be the most impactful as it generates a QPF bullseye over SE Michigan. The more likely solution brings the low track either over Lower MI or Lake Huron, pushing the QPF bullseye into Ontario and supporting more of a convective/showery rain event than a broad stratiform rain. Lean moisture depth initially will be supplemented as moisture gets drawn in from a coastal Atlantic low. Wherever the low ends up, this moisture wraps along the isentropic slope which contributes to the aforementioned higher QPF potential. Otherwise, expecting a standard influence of clouds/precipitation on temperature prospects for this weekend, with the outgoing NBM forecast in line with ensemble means.
MARINE...
The central Great Lakes remain under the influence of high pressure now centered over southern Ontario maintaining light easterly turning southerly winds. Winds continue to veer to the southwest by tonight as the high departs for the Northeast ahead of low pressure dropping out northern Canada. Once the shift to SW flow occurs, winds undergo steady strengthening into Friday with gusts over northern Lake Huron peaking between 20-25kts (10-20kt gusts over the rest of the region). Aforementioned low is expected to become a closed low as it crosses the Great Lakes resulting in slow progression across the area through the weekend however this should also winds under 30kts, instead generally peaking between 15-25kts. Periodic showers accompany this low as will waterspout chances as the cooler airmass is reinforced.
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.DTX WATCHES/WARNINGS/ADVISORIES... MI...Frost Advisory until 9 AM EDT this morning 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.....SC DISCUSSION...MV MARINE.......KDK
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NWS DTX Office Area Forecast Discussion