833
FXUS63 KGRR 240037
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
837 PM EDT Fri Oct 23 2026
.KEY MESSAGES...
- Dense Fog Saturday Morning; Patchy Fog on Sunday
- Pattern Change ahead with chances for rain beyond midweek
&&
.UPDATE...
Issued at 836 PM EDT Fri Oct 23 2026
Main concern this evening continues to be fog potential into the
overnight hours. Southeast flow is forecast to enhance low-level
moisture off of Lake Erie with light winds which is favorable for
fog formation like last night. One caveat is there will be some
high clouds in play, though with hybrid advection fog scenarios
like this that`s not always a deterrent. Forecast soundings are
favorable with moisture trapped under a strong low-level
inversion. Dense fog is possible areawide, with two areas in
particular worth monitoring. The first is from JXN northeast into
LAN and GRR where the best trajectory of moisture off of Lake Erie
is. The other is the lakeshore north of MKG where southwest winds
have led to some localized fog enhancement the last few nights
and LDM`s observation suggests may be underway again tonight. Any
fog that develops is likely to be slow to mix out given lower sun
angles this time of year, potentially lingering into mid morning.
&&
.DISCUSSION...
Issued at 157 PM EDT Fri Oct 23 2026
- Dense Fog Saturday Morning; Patchy Fog on Sunday
High pressure will continue dominate the weather pattern with
light winds and warmer air through the weekend. The light winds,
high pressure, clearing skies is a great recipe for morning fog.
There is some question if it forms later. However, the flow from
the east should allow for moisture to converge overnight and fog
to form across the region. Models remain consistent with highs 10
to 15 degrees above normal with Max temps in the upper 60s to low
70s across the lower Peninsula.
The flow will shift Saturday night into Sunday and this will
lessen the chance for fog development. However, given radiational
cooling, clearing skies and light winds overall, patchy fog will
be again possible Sunday morning, though it should be less dense
than Friday and Saturday.
- Pattern Change ahead with chances for rain beyond midweek
The upper level pattern has the high shifting southward and
flattening next week. However, sfc high pressure should remain
stout enough to keep any moisture bands to only effect the
northern half of the lower Peninsula Monday and Tuesday. The
ensembles diverge on timing but the cold front associated with a
low pressure system tracking from the Canadian Rockies to Hudson
Bay will likely bring cooler air into Michigan dropping highs
closer to normal, in the upper 50s to mid 60s.
Warm air advection midweek will correspond with a deepening
trough that will swing through the region and is the next chance
showers. Pwats are potent so about a quarter inch of rainfall is
possible.
Models continue to diverge after in the movement, timing and
postilion of the upper level pattern. So a continued low
confidence in the forecast for the end of next week.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 723 PM EDT Fri Oct 23 2026
VFR conditions are expected at the beginning of the period, but
another round of fog is expected overnight through tomorrow
morning across much of lower Michigan. Highest probabilities of
LIFR ceilings and visibilities are at LAN and JXN, followed
closely by GRR and MKG. Confidence is low that fog will develop at
BTL and AZO, as fog did not develop there the previous night, and
model probabilities are much lower west of US-131. Fog should
linger through mid morning, with VFR conditions thereafter.
BRC
&&
.MARINE...
Issued at 157 PM EDT Fri Oct 23 2026
Fair winds and waves will dominate the pattern today. Another
round of fog will be possible Saturday and Sunday morning and may
affect the harbors and portions of the nearshore, mainly north of
Grand Haven. Southerly winds will increase tomorrow, upwards of 10
to 20 kts and will build waves to 2 to 4 feet north of Whitehall,
persisting into Sunday morning.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.
&&
$$
UPDATE...Thomas
DISCUSSION...Ceru
AVIATION...BRC
MARINE...Ceru
NWS GRR Office Area Forecast Discussion
