Okemos, Michigan Weather Forecast Discussion

016
FXUS63 KGRR 252256
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
656 PM EDT Thu Sep 25 2025
.KEY MESSAGES...
- Lingering showers this afternoon and fog tonight
- Mainly dry through next week with average to above average temps
&&
.DISCUSSION...
Issued at 230 PM EDT Thu Sep 25 2025
- Lingering showers this afternoon and fog tonight
Main part of the upper low is over the heart of the forecast area as
of 18z this afternoon. A few showers remain ahead of it as it swings
to the east. There have also been a few showers along the lakeshore
with the appearance of some lake breeze convergence. In reality,
there is not much directional convergence present, but maybe some
moisture convergence with dew points a little higher near the lake,
and somewhat of an unstable atmosphere with the upper low/cold pool
aloft still overhead. Anti-cyclonic flow aloft building in through
this evening, along with the loss of diurnal heating should allow
any showers to dissipate by sunset.
Contrary to conditions last night with stratus, we are looking at
more of a potential fog issue tonight. The gradient will be
weakening, but not going completely calm. A weak WSW flow ahead of a
front poised to try and move through tomorrow will allow for just a
little bit of mixing. The longer nights and residual moisture in
place should bring some fog.
- Mainly dry through next week with average to above average temps
We will see a weak upper trough and weak sfc low pass through the
area on Friday. This front should be of little to no impact to our
area. We will be drying out considerably with a flow from the NW
tomorrow pushing the moisture out of the area. Aloft, we will be
much warmer in the mid levels with large scale upper ridging
dominating much more than the weak trough. The lack of moisture in
the lower levels and warmer mid levels will keep most of the area
dry. The exception to this remains across Central Lower where the
higher terrain may help to compensate for the limited moisture and
subsidence. We will not be going any higher than 20 pct for Central
Lower.
Once the trough moves out Friday, we will only see the effects of
the upper ridge that will be centered to our west. For the first few
days through next Monday, the ridge will remain somewhat flat. This
will keep heights from building too high, and keep temperatures from
warming too quick. Plenty of subsidence will keep conditions dry,
and clouds limited.
The upper ridge will build and become more amplified for Tuesday and
beyond as we will have a large upper low over the Western U.S. and
another upper low over the SE U.S.. This will initially warm us up a
few degrees early next week. We could be once again flirting with
80F max temperatures early next week.
The ridge holds, but we end up with a fairly strong flow from the NE
mid week next week. This is a combination of the strong sfc ridge to
our north, and a strengthening gradient over the region with the
potential tropical systems near the eastern seaboard tightening the
gradient. The resulting stronger flow will tap a bit of cooler air
from Eastern Canada and bring it over our region. This does not look
like anything too drastic, but it does look to drop max and min
temps a few degrees.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 656 PM EDT Thu Sep 25 2025
All TAF sites are VFR this evening with skies expected to clear
out in the coming hours. Clear skies and light winds may be
favorable for fog formation, but confidence is lower at this time
due to the presence of 10-15 knot winds just off the surface that
may be keep some mixing going. Have gone with MVFR for AZO/LAN/JXN
where chances are better for fog development. Intermittent IFR
cannot be ruled out but marginal conditions favor keeping IFR out
of the TAFs except for JXN where terrain favors lower
visibilities. Kept MKG, GRR, and LAN prevailing VFR, with
intermittent MVFR possible ar GRR/LAN. So have included temporary
restrictions for those two sites. Any fog that does develop will
dissipate shortly after sunrise with a few VFR clouds and winds of
5-10 knots through the rest of the day.
&&
.MARINE...
Issued at 230 PM EDT Thu Sep 25 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. Northwest winds today and Friday will flip
to southwesterly Saturday. Winds will peak each afternoon at around
10-15 knots as some lake breeze enhancement occurs along the
shoreline. Expect dry conditions across the waters.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.
&&
$$
DISCUSSION...NJJ
AVIATION...Thomas
MARINE...Thomas

NWS GRR Office Area Forecast Discussion