Pewamo, Michigan Weather Forecast Discussion

181
FXUS63 KGRR 162323
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
723 PM EDT Tue Sep 16 2025
.KEY MESSAGES...
- Patchy Dense Fog Again Tonight
- Next Chance of Rain this Weekend
&&
.DISCUSSION...
Issued at 256 PM EDT Tue Sep 16 2025
- Patchy Dense Fog Again Tonight
Continued light east flow will allow for another area of fog to
form across the eastern zones again late tonight and persisting
for an hour or so after sunrise on Wednesday. Current dew point
and temperature forecast suggests fog will be as extensive but
perhaps not as dense as last night.
- Next Chance of Rain this Weekend
Blocking pattern finally breaks down this weekend with the upper
ridge being replaced by shortwave troughing by early next week.
Model guidance agrees on the general pattern but shows quite a
bit of ensemble spread and run to run instability in the details.
Chance POPs look good for now Sunday and Monday as two separate
waves move along a slow moving baroclinic zone. Low confidence
forecast continues for next week given divergent forecasts of the
upper and sfc pattern with the potential for another blocking
pattern to become established.
&&
.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 723 PM EDT Tue Sep 16 2025
With clear skies, light winds, and low dew point depressions
across the region, light to moderate fog development is possible
by 09z or so. Interestingly, the NBM guidance is much more
pessimistic with fog development than standalone high res models
such as the HRRR and Nam3km, or even coarser models such as the
GFS and ECWMF. However, MOS guidance is just about universally in
agreement with light fog development. Fog could briefly be dense
at LAN and JXN in the 10z-12z time frame, but not confident enough
to put 1/4sm visibilities in the TAFs there. Very light and at
times variable winds continue into Wednesday outside of a lake
breeze pushing through MKG during the afternoon.
&&
.MARINE...
Issued at 256 PM EDT Tue Sep 16 2025
Marine weather looks to be benign through the rest of the week.
Similar to today, predominantly easterly flow will become westerly
in the afternoon Wednesday as the lake breeze develops. Winds
increase to 10-15 knots later Thursday but impacts will be low with
northeasterly flow being predominantly offshore. An approaching low
pressure system increases winds to 15-20 knots Saturday morning,
however once again flow looks to be offshore. Waves will be 2 feet
or less through this period. Conditions will be quiet through Friday
with a 20 to 40 percent chance of showers through the weekend.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Ostuno
AVIATION...Hoving
MARINE...Thomas

NWS GRR Office Area Forecast Discussion