620 FXUS63 KGRR 150702 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 301 AM EDT Thu Oct 15 2026 .KEY MESSAGES... - Becoming wet, windy, and colder through Friday - Extended dry period with moderating temperatures next week && .DISCUSSION... Issued at 301 AM EDT Thu Oct 15 2026 - Becoming wet, windy, and colder through Friday Everything remains on track for the evolution of our weather from today through Friday evening, with no major changes noted at this time. Plenty of clouds remain from the stratocumulus clouds that moved overhead on Wednesday. There are some breaks in this, but high clouds are widespread, and the holes in the lower clouds are filling in. We will see deep moisture advect over the area this afternoon as the strengthening low level jet associated ahead of the upper wave and developing sfc low will approach late this afternoon. It is with this feature that we will see the most widespread rain with this entire system. The sliver of instability (elevated in nature based between 850 and 700 mb) that may affect the I-94 corridor would also be maximized at that time. All of this would be through just before 06z when the low level jet peels away and the occluded front moves through. The next wave of showers will then come right ahead of the secondary cold front/cold conveyor belt that will surge in from the NW. This comes through centered around 12z Friday give or take a couple of hours depending on the northern or southern portion of the forecast area. This is associated at the leading edge of the upper trough and cyclonic flow arriving. The passage of these features will ultimately shift the mean low level flow to become from the NNE. Lake effect rain showers will be likely initially from the NW, and will shift offshore by late afternoon. It is from mid morning until the wind shifts offshore when the best chance of lake induced thunder will be possible with just short of 1,000 J/kg of CAPE available. Wind will be another aspect of this system. Right now, it looks like most places will see gusts to around 40 mph Friday. May just be short of advisory criteria inland, where instability will be a bit less than over the warmer waters. A few showers will remain possible inland through the daylight hours, and a few may linger into mid-evening. It will be shortly after 00z Saturday the the upper trough moves out, and the flow becomes anti-cyclonic. - Extended dry period with moderating temperatures next week Strong subsidence will build in quickly behind the departure of the upper trough by Saturday morning. The upper air pattern over the CONUS then transitions to a much more amplified trough/ridge/trough pattern from the West Coast to East Coast in almost an Omega block. The strong upper trough on Friday will close off along the East Coast, and strong energy moves toward the West Coast from the Pacific. This will place Michigan in between under the influence of the strong ridge. This means plenty of dry weather, with sunny days and cool nights. There will be attempts of short waves trying to flatten the ridge. It seems that the ridge should remain intact through at least mid-week. Later in the week, there have been indications that there may be a trough that tries to close off overhead next Thursday. Way too much uncertainty seven days out to try to pin down the details. Generally speaking, we will see above average temperatures, and below average precipitation. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 156 AM EDT Thu Oct 15 2026 We are seeing a variety of conditions at the terminals this morning, ranging from some small areas of clear skies to lower clouds in the MVFR category. The trend for the night will be for the lower clouds to become more widespread as they expand. The clouds should end up mainly MVFR. There may be some breaks at times, but will side on the pessimistic side. The clouds will then hold on into the afternoon. We will see widespread showers move in over the area from West to East after about 18z. Conditions will then deteriorate late afternoon and this evening as we go down into the LIFR category with visibilities and ceilings. Showers will continue the majority of the time, but may scatter out a bit right at the end of the period. Low level wind shear is expected at all but the KMKG terminal after 00z as the wind core aloft moves overhead. The winds at the sfc will be from the SE at less than 10 knots, while 45 knots or so from the SW at 2k ft agl. && .MARINE... Issued at 301 AM EDT Thu Oct 15 2026 We will be issuing a Gale Warning for the core of the upcoming wind/wave event, with a Small Craft Advisory on the front end of it from this evening through the beginning of the Gale Friday morning. Winds will increase quickly with the first surge of colder air late this evening, and overnight. The strongest of the winds will come with the deep colder air that arrives Friday morning. Very unstable conditions over the lake will allow all of the wind aloft to reach the sfc. Waves will build quickly also. After a break on Saturday with high pressure overhead, winds will increase once again Saturday night through Sunday night under a tight gradient from the high to our south, to a strong low across Canada. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...Small Craft Advisory from 11 PM this evening to 11 AM EDT Friday for LMZ844>849. Gale Warning from 11 AM Friday to 2 AM EDT Saturday for LMZ844>849. && $$ DISCUSSION...NJJ AVIATION...NJJ MARINE...NJJ

NWS GRR Office Area Forecast Discussion