Napoleon, Michigan Weather Forecast Discussion

568
FXUS63 KGRR 270615
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
215 AM EDT Sat Sep 27 2025
.KEY MESSAGES...
- Dry and mild conditions to persist through next week
&&
.DISCUSSION...
Issued at 205 PM EDT Fri Sep 26 2025
- Dry and mild conditions to persist through next week
No need for any changes to the dry and mild forecast through next
week.
A weak front is currently dropping south through the area this
afternoon. It is located near a line from Pentwater to Northern
Saginaw Bay as of 2 pm EDT/18z. A few sprinkles were trying to
generate along M-55 just after noon, but they have not grown to
anything more than that. The best chance for anything this afternoon
with be closer to Lake Huron/Saginaw Bay were some lake breeze
convergence may help to boost the updrafts just enough.
We will likely see some patchy fog tonight, although it will
probably not be as extensive as last night/this morning. We have had
a chance to mix out some of the boundary layer moisture that
remained yesterday. In addition, there is a little more wind just
off of the sfc. This will lead to a little bit more mixing to
mitigate a perfect radiational fog setup.
Looking more longer term, we continue to expect upper ridging to
dominate the weather over the region through next Friday. The ridge
still looks to be fairly broad and flat in nature into Monday. It is
being flattened by a stronger upper low across Western Ontario. We
will hold on to mainly clear skies, another weak front will drop
through the area on Sunday. There will not be much change in the air
mass. It will just act to suppress the really warm air to our SW
under the heart of the ridge.
The ridge does amplify early next week, helping to reinforce the
strong subsidence over the area and very mild to warm temperatures.
This strengthening of the upper ridge comes as it gets squeezed by a
strong upper low coming into the Western U.S. and the tropical
system that could come into the East Coast. It looks to hold steady
over us.
The 500 mb heights increase to almost 590 dam. This normally would
bring highs well into the 80s and approach 90F. However, the way the
sfc ridge orients itself, we will develop a low level NE flow that
will funnel in a more shallow cooler air mass from Eastern Canada.
This will bring temperatures down a little into the mid 70s, versus
the 80 degree temps expected early in the week.
&&
.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 210 AM EDT Sat Sep 27 2025
VFR conditions continue with a few non TAF sites dropping down to
VLIFR. This is indication of the potential for another round of
patchy dense fog. Winds are calm across most areas. The surface is
slightly drier with dew point depressions in the 1 to 2 Degree
range. This differs from last night when dewpoint depressions
were zero.
 While there does remain the potential for fog, it is mostly north
of the I 96 corridor. The only TAF site of concern is MKG. So have
included some IFR vsbys early this morning.
 Any fog/mist and reducing conditions will improve shortly after
sunrise. Winds will mix out with southwest winds this afternoon,
though they should be around 10 kts or lower.
&&
.MARINE...
Issued at 205 PM EDT Fri Sep 26 2025
Conditions are expected to remain below Small Craft Advisory/Beach
Hazards Statement levels the next several days as a weak gradient is
in place across the area. North winds today will flip to
southwesterly Saturday. Winds will peak each afternoon at around 10-
15 knots as some lake breeze enhancement occurs along the shoreline.
There is also a signal for a wind enhancement early Sunday morning
of around 10-15 knots near Big and Little Sable points as a wind
maxima moves south across the lake. Expect dry conditions across the
waters.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.
&&
$$
DISCUSSION...NJJ
AVIATION...Ceru
MARINE...Thomas

NWS GRR Office Area Forecast Discussion