textproduct: Grand Rapids

KEY MESSAGES

- Low clouds and light rain from remnants of Isaias today

- Warm air continues through Monday; Rain chances Tue and Wed

- Chance for showers and storms late this week

DISCUSSION

Issued at 230 AM EDT Sun Oct 11 2026

- Low clouds and light rain from remnants of Isaias today

Post tropical cyclone Isaias will bring heavy rainfall through the southern Appalachians and move through the Mid Atlantic today. Southeast Michigan remains on the edge of the tropical moisture and will bring some low clouds to regions south of I 96 and west of the US 131 today. Best chance for rain will be through the east of I 69. Overall rainfall will be fairly light.

- Warm air continues through Tuesday; Rain chances Tue and Wed

The warm air conveyor belt will continue through Tuesday. Max temperatures through this time frame will be 10 to 20 degrees above normal. Monday's Max temps are expected to be in the upper 70s to low 80s across lower Michigan. These temps are associated with a positively tilted upper level ridge, which should keep any showers north of the lower peninsula through Monday. That ridge will break down Monday night into Tuesday. so expect a weak upper level trough to swing a mid level system through the area into Tuesday. QPF is around 0.25 at this time.

The pattern flattens out Tuesday into Wednesday with a more zonal trend which could keep the best rainfall on Tuesday north of US 50. However,the EC ensemble PWATS for that band through northern lower MI is around 1.5 inches. If that pool of moisture shifts to the south then locally higher amounts of rainfall could be possible. Lows will be in the mid 60s by Tuesday morning, peaking into the upper 70s Tuesday afternoon. So a warm, rain for the most part.

Depending where the moisture band sets up on Wednesday, the southern half of lower Michigan could see some decent rainfall Wednesday, though currently the best PWATS are south of the I 94 corridor. - Chance for showers and storms late this week

A pattern shift is ahead, though latest mid range guidance pushes the pattern change to the end of the work week. Any rain and clouds will temper temperatures through Midweek. Max temps should remain above normal through Thursday. A cold front late this week will drop temperatures below normal, bringing more Autumn-esque temperatures.

The guidance continues to become out of phase beyond Thursday. The GFS brings a deepening synoptic system through the area Friday. The EC has a much shallower solution, with any moisture bands bifurcating the area. The NAEFS and EC ensembles are similar, which gives more credence that the northern portion of the system remains through the Upper Great Lakes, and a vort max associated with the southern portion of the system skirting through IN and Ohio. That should mean any rain chances Friday should be south of the I 96 corridor, and heaviest rain south of Michigan.

AVIATION /12Z TAFS THROUGH 12Z MONDAY/

Issued at 708 AM EDT Sun Oct 11 2026

The remnants of Isaias will move through the Mid Atlantic and moist flow from it should drop cigs to IFR at JXN, LAN, AZO and BTL. JXn has already dropped to IFR with AZO and BTL at MVFR. The TAF sites that will see the worst conditions will be JXN and potentially LAN. AZO should see IFR this morning, before improving early afternoon. Low cigs will continue through most of the day at JXN and LAN. Expect improving conditions after 22Z. GRR should see MVFR cigs but is far north enough to be outside the thickest low clouds. LLWS is expected through the first few hours of this TAF cycle but the LLJ will move to the east after 07Z.

The only TAF site that should see rain is JXN, however there is a low probability chance for VCSH at BTL and LAN.

GRR WATCHES/WARNINGS/ADVISORIES

MI...None. MARINE...Small Craft Advisory until 5 AM EDT early this morning for LMZ846>849.

GRR WATCHES/WARNINGS/ADVISORIES

MI...None. MARINE...None.