textproduct: Grand Rapids

KEY MESSAGES

- Deepening fall system to move through the Great Lakes

- Mainly dry this weekend and into early next week

- Cool temperatures this weekend then moderating some next week

DISCUSSION

Issued at 300 PM EDT Wed Oct 14 2026

- Deepening fall system to move through the Great Lakes

Two distinct upper shortwave troughs can be seen this afternoon in satellite imagery, one over the Central Rockies and the other moving from the Canadian Rockies into the Canadian Prairies. Both of these shortwaves will move towards the Great Lakes and phase with one another as they approach from the west. Rain will spread in towards daybreak on Thursday. The most widespread rain will move Thursday afternoon and evening as the right entrance region of and upper jet moves overhead. A low level jet will impact southern portions of the state, towards I-94 especially. 850mb moisture transport is very strong Thursday evening into Thursday night. All areas will see rain with one half to one inch of rain likely. Cannot rule out some thunder as the cold front swings through, but the better instability will remain off to our south.

Lake effect rain showers will combine with diurnal rain showers on Friday for another wet day. Delta T's will rise into the upper teens C which will result in MUCAPE values over the lake on the order of 600 j/kg. Feel waterspouts are a possibility Friday morning before the stronger winds move in during the afternoon.

We are looking at gale force winds on Lake Michigan, but on the land we may not meet advisory criteria with wind gusts expected to be in the 30-40 mph range as of now.

- Mainly dry this weekend and into early next week

Ridging will take over for the weekend and early next week. We are looking at a dry forecast from Saturday all the way into Wednesday. BUFKIT profiles show a very dry atmosphere so there is fairly high confidence we remain dry Saturday-Wednesday.

- Cool temperatures this weekend then moderating some next week

We will cool into the 50s for highs this weekend as high pressure moves through the Great Lakes. Lows in the 30s are anticipated for Saturday morning and Sunday morning. We are likely looking at frost and freeze headlines at least on Saturday.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 112 PM EDT Wed Oct 14 2026

Satellite and observational trends show MVFR cigs are lifting to VFR, however intermittent MVFR is likely through late afternoon. VFR is expected then this evening into the first part of the night, before clouds increase around 3500 ft tonight, potentially falling to 2500 ft with boundary layer cooling. Best signal for MVFR potential is LAN/JXN, with weaker low-level moisture further west so have gone with SCT 2.5kft cigs at other terminals for now. At these sites, MVFR is forecast to set in near or shortly after 18z.

MARINE

Issued at 300 PM EDT Wed Oct 14 2026

A deepening fall system will move through the Great Lakes Thursday and Friday. North winds will increase behind the low starting Friday morning. We have a Gale Watch in place beginning at 11am Friday and lasting into Friday night. Winds are expected to reach 35 to 45 knots on the lake during the peak of the event Friday afternoon and evening. The winds will be running parallel down the shoreline, but waves will still be high reaching 10+ feet on Friday. The largest waves will be at the south end of the lake.

When advisory/warning decisions are made we may need to have a Small Craft Advisory on the front end of what will likely be a Gale Warning. Waves will become hazardous to smaller craft in our area starting as early at 400am Friday. Southwest flow develops rapidly behind the departing system and we are will likely see large waves again Saturday evening into Sunday.

GRR WATCHES/WARNINGS/ADVISORIES

MI...None. MARINE...Gale Watch from Friday morning through late Friday night for LMZ844>849.