434
FXUS63 KGRR 221854
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
254 PM EDT Thu Oct 22 2026

.KEY MESSAGES...

- Mild and dry weather with morning fog through the weekend

- Cooler temperatures and modest rain chances return next week

&&

.DISCUSSION...
Issued at 209 PM EDT Thu Oct 22 2026

- Mild and dry weather with morning fog through the weekend

Our extended stretch of pleasant fall weather continues for a few
more days, thanks to a building ridge of high pressure and the
return of southerly low level flow. Before we get to the next few
days though, there is yet another potential for overnight and
early morning fog in several areas tonight, with perhaps a slight
increase in coverage as well. Light northeasterly winds are
expected to carry increased low level moisture into the area this
evening, and this should boost the potential for fog as radiative
cooling commences under clear nighttime skies. High resolution
model guidance (RRFS to be specific) continues to produce a
convincing signal for fog locally, and when combined with the
pattern and repeated fog development over the past few days,
another round is expected tonight, likely with an increase in
coverage.

From tomorrow through Sunday, the aforementioned upper ridge will
continue to steadily build overhead, while a deep low pressure
system across the Canadian Prairie drives southerly low level
winds. This will produce consecutive days of well above average
temperatures across lower Michigan (roughly 8-12 degrees above
seasonal averages), equating to highs in the mid 60s to near 70s.
Meanwhile, precipitation chances remain near zero throughout the
weekend.

- Cooler temperatures and modest rain chances return next week

Between Sunday night and Monday afternoon, a weak back-door cold
front will sink into lower Michigan as a shortwave passes well to
our north. This will drive a steady cooling trend that will
persist through mid-week, bringing temperatures back to near
seasonal averages (highs in the upper 50s to low 60s / lows in the
mod 30s to low 40s). Confidence in the temperature forecast is a
bit lower overall on Monday, owing to ensemble member variation in
the timing of the cold front and trailing cold air advection. This
uncertainty is highlighted by increasing temperature forecast
spreads on Monday in particular, with decreasing spreads Tuesday
onward as a low-variance high pressure pattern becomes
established.

Meanwhile, in spite of the presence of the cold front,
precipitation chances remain rather low early next week, likely
due to meager moisture return and weak forcing mechanisms. While
there remains considerable variability among ensemble members,
latest trends have shifted meaningful precipitation chances toward
to mid-week period, and overall probabilities have reduced.
Still, we do see the return of at least mentionable probabilities
of light rain by Wednesday (20-30%), so there is at least a
reasonable potential for some light rain toward the end of the
forecast period.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 100 PM EDT Thu Oct 22 2026

Clear and quiet through the rest of the day. Expecting fog to
develop across the middle of the Lower Peninsula in the predawn
hours. Given the position of the surface high overnight, there
will be an increased chance of LIFR fog - with tempos down to a
1/4SM and JXN/LAN/GRR around sunrise and a couple hours
thereafter. Fog should lift and thin during the mid-morning hours.

&&

.MARINE...
Issued at 209 PM EDT Thu Oct 22 2026

Light winds and very low wave heights of 1 foot or less persist
through tonight. Sustained south-southeast winds increase to near
10 kt tomorrow, and to 15 to 20 kt tomorrow, causing wave heights
to increase to between 2 to 3 feet by Saturday afternoon, mainly
north of Whitehall. These conditions largely continue through
Sunday, but a cold front will bring a quick transition to
northerly winds with similar speeds by Monday.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.

&&

$$

DISCUSSION...BRC
AVIATION...Mann
MARINE...BRC

NWS GRR Office Area Forecast Discussion