Flat Rock, Michigan Weather Forecast Discussion

886
FXUS63 KDTX 180735
AFDDTX
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
335 AM EDT Thu Sep 18 2025
.KEY MESSAGES...
- Highs well into the 80s today outside of the Thumb.
- A weak cold front brings chances for scattered showers and storms
focused north of I-69 this afternoon-evening.
- A little cooler Friday into Saturday. Warmer with increasing rain
chances by the end of the weekend.
&&
.DISCUSSION...
Visible and water vapor satellite highlight the next shortwave set
to cross the Great Lakes today. Trailing backdoor cold front sinks
through southern lower MI starting this afternoon through the
evening as the wave reaches southern Ontario. Lower level flow in
advance turns more westerly allowing a piece of the richer theta-a
airmass over the upper Mississippi to be drawn over SE MI pushing
surface Td`s into the lower 60s. CAM solutions have trended more
bullish on MLCAPE relative to prior night runs with most now
favoring several hundred J/kg by late afternoon focused north of I-
69. While the backdoor front itself isn`t particularly strong, given
its nature, afternoon timing during typical lake breeze development
offers enhancement of frontal forcing particularly near the Saginaw
Bay as the boundary turns into a hybrid cold front-lake breeze. As a
result, confidence is increasing for scattered showers and
thunderstorms (due to the higher available instability) to develop
over the Tri-Cities and western Thumb around/after 18Z this
afternoon. Exactly how far south this convection survives late
afternoon-evening still carries uncertainty though have extended
chance PoPs (25%) to the I-69 corridor and slight chances (15%) to
the M-59 corridor.
Modestly cooler Friday as the front settles near the state border
setting up northeasterly flow into SE MI. Given the winds off Lake
Huron, the Thumb will be the coolest area with highs ranging from
near 60 on the lakeshore to upper 60s-near 70 inland. Areas south of
M-59 stand the see the warmest temps with highs still in the mid-
upper 70s to lower 80s towards the Ohio border. Mid-upper ridging
then is briefly re-established Friday night-Saturday maintaining the
dry pattern and above normal temps in the 70s and low 80s.
Ridging pushes east of the region by late Saturday as a warm front
tied to low pressure over the upper Midwest lifts through the Great
Lakes. Fropa brings the next shot to see a few scattered showers
though lingering dry airmass from prior high keeps these chances on
the lower side (

NWS DTX Office Area Forecast Discussion