851 FXUS63 KGRR 182250 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 650 PM EDT Sun Oct 18 2026 .KEY MESSAGES... - Tranquil and Relatively Warm This Week && .DISCUSSION... Issued at 205 PM EDT Sun Oct 18 2026 - Tranquil and Relatively Warm This Week Minimal weather concerns this week as there will be a tendency for high pressure over the Great Lakes region and beyond much of the time. A very El-Nino-looking split upper level jet is over North America this week, and Michigan will be under weak flow through Wednesday. High temperatures will generally reside in the mid to upper 60s while the 30-year normal highs slip into the upper 50s. With the mostly clear skies and light winds, nightly lows will be closer to normal, between the mid 30s and mid 40s. Areas of fog Tuesday morning and Wednesday morning are possible. After today, all ensemble members are very light on winds, until there is just a minor uptick Thursday and and into the weekend when a couple of weak troughs ripple through the pattern. The lack of moisture and lift wouldn`t favor much more than a chance of sprinkles. && .AVIATION /00Z TAFS THROUGH 00Z TUESDAY/... Issued at 650 PM EDT Sun Oct 18 2026 Little in the way of aviation impacts is expected over the next 24 hours. Clear skies are expected until into the early afternoon Monday when cirrus approach from the west. LLWS climbs to 25-30 knots tonight as a low-level jet sets up around 2kft but surface winds look just elevated enough to keep below inclusion thresholds. Look for predominantly southwest flow, becoming west- southwest in the afternoon. After sunset, all sites except MKG see winds fall to aob 10 knots, with MKG seeing gusts to around 20 knots through the night before tapering off in the morning. This will be in response to a weakening of gradient winds due to an approaching high. && .MARINE... Issued at 205 PM EDT Sun Oct 18 2026 Wind and wave observations in the nearshore have been firmly in small craft advisory territory with gusts 25 to 30 knots, waves 3-5 feet around South Haven, and greater than 6 feet north of Holland. Gale force gusts have so far only been in northern Lake Michigan and should remain that way. Winds weaken gradually tonight and conditions will improve south of South Haven, but waves may take until later Monday morning to come down between Holland and Manistee. After that, no concerns for the next several days. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...Small Craft Advisory until 11 PM EDT this evening for LMZ844. Small Craft Advisory until 11 AM EDT Monday for LMZ845>849. && $$ DISCUSSION...CAS AVIATION...Thomas MARINE...CAS

NWS GRR Office Area Forecast Discussion