410 FXUS63 KGRR 142317 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 717 PM EDT Wed Oct 14 2026 .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 /00Z TAFS THROUGH 00Z FRIDAY/... Issued at 717 PM EDT Wed Oct 14 2026 Chaotic ceilings are expected to start the forecast. Latest satellite and observational trends suggest a breakout to VFR for AZO/BTL/JXN near 00z, occuring a few hours later for the other terminals. Even with this, ceilings are expected to remain borderline VFR/MVFR, especially overnight once boundary layer cooling develops with cigs from 2.5-3.5 kft. Beginning late morning Thursday conditions then become solidly MVFR. Conditions deteriorate further Thursday afternoon and evening as a low pressure system brings showers/fog and low clouds to the area. Conditions are likely to deteriorate to IFR between 18z-21z and periods of LIFR are possible, though confidence is to low to include LIFR conditions at this time range (20-30 percent). Once conditions fall they will remain poor through the rest of the TAF period. && .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. && $$ DISCUSSION...Duke AVIATION...Thomas MARINE...Duke

NWS GRR Office Area Forecast Discussion