Allegan County Michigan Weather Forecast Discussion

017
FXUS63 KGRR 121121
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
721 AM EDT Sun Oct 12 2025
.KEY MESSAGES...
- Patchy Fog This Morning
- Mostly Dry through Next Week
&&
.DISCUSSION...
Issued at 336 AM EDT Sun Oct 12 2025
- Patchy Fog This Morning
Clear skies and light winds have resulted in radiational cooling
and dew point depressions are around 0 to 1 degree. Seeing
visibilities dropping along the I-94 and 127 corridors and expect
this to continue to expand westward across the area. Winds aloft
may keep fog from becoming more widespread and dense. Visibilities
have been bouncing a bit over the past hour which matches with
patchy fog. Will continue to monitor if fog is able to become
dense and widespread enough for an advisory. Otherwise, any fog
this morning should dissipate within an hour or two after sunrise.
- Mostly Dry through Next Week
High pressure will be present through most of the upcoming week.
A weakening front approaches the area Monday, while precipitable
water values increase, lift decreases. Therefore not expecting
any rain, especially with the drier low levels and the shallow
moisture noted within the forecast soundings. NBM probabilities
have dropped below 20 percent across the west from our previous
forecast due to the factors above. Our chances for rain have also
trended downward for Tuesday night as northerly flow and high
pressure with drier air quickly fills in. PoPs have dropped to 20
percent with some solutions trying to sneak some rain into our
southwest ahead of the high, however with recent trends these PoPs
will likely fall below 20 percent.
High pressure remains in place for Wednesday and Thursday with
the potential for some frosty nights, especially Wednesday night
as temperatures fall into the upper 20s to mid 30s. The pattern
changes with a stronger shortwave moving in Friday/Friday night.
At this time there is a better correlation of lift and moisture
hence the higher probabilities of precipitation in the 30 to 50
percent range for Friday night.
&&
.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 721 AM EDT Sun Oct 12 2025
Dense fog has developed across the area reducing visibilities down
to a quarter mile and ceilings around 100 to 200 feet.
Visibilities should gradually improve toward 14Z with ceilings
scattering out. Southeast to east winds and VFR conditions are
then expected for the remainder of the day. There is a potential
for fog to develop once more tonight into Monday morning, however
clouds could limit visibility reductions.
&&
.MARINE...
Issued at 336 AM EDT Sun Oct 12 2025
Southeast winds around 10 to 20 knots are expected today with
wave heights of a foot or less. This easterly flow will continue
until Monday when winds slowly veer to the north. Our next
potential for hazardous winds and waves is not until Friday as our
next system moves in bringing with it chances for rain.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Dense Fog Advisory until 10 AM EDT this morning for MIZ038>040-
     044>046-051-052-057>059-065>067-072>074.
MARINE...None.
&&
$$
DISCUSSION...RAH
AVIATION...RAH
MARINE...RAH

NWS GRR Office Area Forecast Discussion