121
FXUS63 KGRR 051723
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
123 PM EDT Fri Sep 5 2025

.KEY MESSAGES...

- Strong winds with cold frontal passage today

- Cooler period through the weekend due to successive fronts

- Return to normal temps next week

&&

.DISCUSSION...
Issued at 350 AM EDT Fri Sep 5 2025

- Strong winds with cold frontal passage today

 Gusty winds are expected across Michigan today. The strongest
gusts will be along the lakeshore, especially north of the I 96
corridor. A swath of winds from a low level jet will make its way
across the state along the cold front. While there remains a 50
kt LLJ at 850mb the question is whether that will mix to the
surface.

DCAPE remains strongest further north but only 300 J/kg.
So not the best forcing. However 0-3KM shear is upwards of 40kts.
so given rain loading with frontal passage a brief period of wind
gusts upwards of 40 to 45 mph is possible. As the the frontal
rain band moves to the east the winds will shift from the
southwest to a more westerly component with strong winds moving
across the area. The strongest gradient remains along the
lakeshore. Latest wind reports upwards of 40 mph on lakeshore but
remain below that inland. A secondary front is passing through
Wisconsin and will move across the Lake mid morning. This will
bring another round of gusty winds.


- Cooler period through the weekend due to successive fronts

While gusty winds will continue through the morning the regions
weather will be dominated by a large upper level low over southern
Canada. As that low moves eastward, successive troughs will
filter through bringing chances for showers Saturday and Sunday.
The limiting condition to any precipitation will be drier air
just south of the trough which will limit QPF. Temps will be 10 to
15 degrees below normal with highs in the 60s. That trough will
have weaker low level winds, so while gusty winds tomorrow will be
possible, not expecting them to be as strong as today.

- Return to normal temps next week

 As the upper level low moves eastward and flattens,temperatures
will increase into next week with temperatures returning closer to
normal with another chance for precipitation Tuesday into
Wednesday.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 122 PM EDT Fri Sep 5 2025

Gusty winds remain the primary concern for all TAF sites over the
next 24 hours. SCT to BKN clouds around 5kft are expected today
and again Saturday. As for winds, west winds of 15-20 knots with
gusts as high as 30 knots will persist through this evening before
subsiding near sunset. Winds generally hold in the 5-10 knot range
overnight before increasing to 10-15 knots gusting to 20 knots
late Saturday morning.

&&

.MARINE...
Issued at 322 AM EDT Fri Sep 5 2025

Dangerous winds and waves will continue today into Saturday
Gales of 40kts or higher are expected for all marine zones
are expected this morning with waves of more than 10 feet
expected at times. Muskegon GLERL has reached 38 kts with Big
Sable Ob at 40 kts.  Some improvement in conditions late Friday
but hazardous winds and waves to small craft and swimmers should
persist into Saturday.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement through Sunday afternoon for MIZ037-043-
     050-056-064-071.
MARINE...Small Craft Advisory until 5 PM EDT Sunday for LMZ844>849.

&&

$$

DISCUSSION...Ceru
AVIATION...Thomas
MARINE...Ceru