963
FXUS63 KGRR 131039
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
639 AM EDT Sun Sep 13 2026
.KEY MESSAGES...
- Slight chance of Rain Today
- Showers and Thunderstorms Possible Tuesday through Thursday
&&
.DISCUSSION...
Issued at 216 AM EDT Sun Sep 13 2026
- Slight chance of Rain Today
A cold front moves through today along with some mid-level
frontogenesis. Moisture is limited however and POP have trended
lower since yesterday. Best chance for rain will be across the
central forecast area this afternoon. Cooler and drier air moves
in behind the front. With the surface high building in tonight,
radiational cooling conditions will be optimized and temperatures
will fall into the 40s in most places, with even upper 30s possible
across the northern interior.
- Showers and Thunderstorms Possible Tuesday through Thursday
A shortwave trough ejects out of the northern Rockies with a
surface low tracking into Canada by Tuesday. A trailing cold
front is expected to touch off showers and thunderstorms Monday
night and Tuesday. Instability and deeper moisture is across
northern Lower Michigan pooling ahead of the cold front, which
sinks south through the forecast area on Tuesday. Precipitable
water surges close 2 inches, so heavy rain potential is there as
the front will be moving slowly and MBE vectors are less than 5
knots.
The front stalls across the southern zones on Wednesday, with a
showers and thunderstorms possible into Thursday as a surface low
tracks along the front across southern Lower Michigan.
&&
.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 640 AM EDT Sun Sep 13 2026
VFR conditions will continue through tonight. Northwest winds
will gust over 20 knots this afternoon then winds diminish to blo
10 knots this evening.
&&
.MARINE...
Issued at 216 AM EDT Sun Sep 13 2026
No changes to the marine headlines. After a brief lull, winds and
waves will increase again on Monday night and Tuesday when south
gales are expected.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement from 11 AM EDT this morning through this
evening for MIZ037-043-050-056-064-071.
MARINE...Small Craft Advisory from 11 AM this morning to 11 PM EDT this
evening for LMZ844>849.
&&
$$
DISCUSSION...Ostuno
AVIATION...Ostuno
MARINE...Ostuno
NWS GRR Office Area Forecast Discussion
