NWS Forecast Discussion

118
FXUS63 KDTX 041851
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
251 PM EDT Sun Oct 4 2026

.KEY MESSAGES...

- Below normal temperatures arrive Monday with highs only near 60
and lows falling into the 30s. Chance for frost is possible Monday
night particularly over the Saginaw Valley/Thumb.

- More seasonably average temperatures return for the midweek period
with little to no rain chances.

&&

.DISCUSSION...

Surface cold front finishes crossing lower MI this evening with only
a low chance for an isolated brief shower as primary moisture axis
has shifted over the eastern Great Lakes. Post-frontal cold
advection in place through the night into Monday as upper troughing
settles over the eastern half of the Great Lakes. Core of the
coolest air arrives Monday keeping tonight`s lows in the upper 30-
lower 40 range precluding a risk of frost. Local 850mb temps fall
towards 0C by midday Monday capping high temps around 60 despite
building high pressure promoting mostly sunny skies. Said high
drifts directly overhead by Monday night leading to calm or near
calm winds under clear skies allowing temperatures outside of the
urban centers to fall into the 30s. Coldest temps expected across
the Saginaw Valley and Thumb where mid 30s are likely offering
potential for areas of frost to develop by Tuesday morning.

High pressure departs for the mid-Atlantic daytime Tuesday as broad
low pressure dives southeast across northern Ontario setting up
south-southwest return flow across southern lower MI. Low pressure
looks to track far enough north that SE MI stays dry save for
perhaps a stray shower towards the tip of the Thumb Tuesday night.
With the area currently favored to reside on the southernmost fringe
of the James Bay upper low, temperatures throughout the midweek
period would hold around the seasonal average, in the mid-upper 60s,
with Wednesday making a run towards 70.

&&

.MARINE...

Surface flow will turn to northwest this evening in the wake of a
weak cold front.  Across Lake Superior, gusts have increased to
occasional low-end gales at the end of fetch.  Given the parent
storm system track is well to the north, the best forcing of lengthy
low gale potential will be across Lake Superior, with lower chances
across the north arm of Lake Huron.  As the cooler air deepens
through the Straits out onto the main body of northern Lake Huron,
wind gusts will increase and approach entry level gales - with the
greatest potential tied to the more aggressive cloud growth
formations. Current forecast package will continue with the Gale
Watch, offering some opportunity for stronger gusts to present
themselves upstream.

High pressure builds into the region on Monday into Tuesday -
flattening out the wind field for a day or so.  Southwest winds will
increase later Tuesday with the approach of the next system across
the northern lakes region.  Small craft conditions are likely across
Saginaw Bay and possible down the southern Huron shoreline.

&&

.PREV DISCUSSION...
Issued at 1248 PM EDT Sun Oct 4 2026

AVIATION...

Full sun and breezy/mild SW wind precedes a cold front on its way
through Lower Mi this afternoon and early evening. The front is too
moisture starved for shower production but is supporting borderline
MVFR/VFR ceiling along and behind a modest NW wind shift. After an
initial cloud decrease this evening, the air is cold enough to
activate the Great Lakes for additional cloud production late
tonight. Coverage tends to be areas of low end VFR with stray
patches of MVFR this far south away from the Lake Superior/Michigan
connection. NW surface to cloud layer flow persists late tonight
through Monday morning.

D21/DTW Convection... Thunderstorms are not forecast through the
period.

DTW THRESHOLD PROBABILITIES...

* Low for ceiling 5000 ft this afternoon and evening.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Gale Watch from 8 PM EDT this evening through Monday morning for
     LHZ361-362.

     Small Craft Advisory until 8 AM EDT Monday for LHZ421.

     Small Craft Advisory until 2 PM EDT Monday for LHZ441.

Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&

$$

DISCUSSION...KDK
MARINE.......Mann
AVIATION.....BT


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NWS DTX Office Area Forecast Discussion