049 FXUS63 KGRR 010744 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 244 AM EST Sun Nov 1 2026 .KEY MESSAGES... - Light rain possible early today - Dry conditions into Monday - Wetter conditions Tuesday into the weekend && .DISCUSSION... Issued at 244 AM EST Sun Nov 1 2026 - Light rain possible early today An area of precipitation has dissipated as it moved east across southwest Lower MI. However, some models, such as the HRRR, suggest that another batch of light showers could move northward into extreme southwest Lower MI later this morning, possibly affecting that area with another round of light rain. Cloud bases remain high and a dry sub-cloud layer, as noted on the 01/00Z DTX sounding, will limit precipitation accumulations. We expect predominantly dry conditions from this afternoon onward. - Dry conditions into Monday Satellite shows a sharp upper trough off the west coast with downstream ridging over the intermountain west. This ridge will move eastward and be positioned over the western Great Lakes by Monday afternoon, resulting in synoptic subsidence for our region up through this time. Based on this, it is not surprising that more recently available ensemble and deterministic NWP suggests Monday could be predominantly dry for southwest Lower MI with precipitation holding off until Monday night or Tuesday, while better chances remain west and north of the area. - Wetter conditions Tuesday into the weekend Chances for rain grow substantially starting late Tuesday. As a side note regarding Tuesday, highs are expected to reach the lower 70s, which is about 20 degrees above normal for this time of year. Even Wednesday will be making a run close to 70 degrees. Total QPF for the coming week looks a bit less impressive overall. For example, a sampling of available medium range ensemble guidance (GEFS/ECE/Canadian) shows only about a 50 percent chance of accumulating an inch or precipitation between now and Friday evening. However, there is one important caveat regarding rain potential later this coming week. There is growing consensus that a cutoff low will form in the Wednesday timeframe somewhere over the midwest. ECE mean 500 mb height forecasts show this, which indicates surprisingly good positional and temporal consistency among the ensemble members. This low develops from the aforementioned upper wave, which by this time will be poised to cross the Mississippi River. During the cutoff process, there is the possibility for mid-level deformation and attendant fgen to materialize somewhere downstream of the upper low, which could in turn produce localized amounts of much greater than an inch of rain towards the latter part of the week. It was interesting to observe in the QPF box and whisker plots the presence of significant outliers indicating this possibility. So the takeaway is that rainfall amounts for the first part of the week have relatively good predictability with low potential for overperforming. The latter half of the week, on the other hand, has much less predictability with a small chance of significant rainfall in a concentrated area. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 135 AM EDT Sun Nov 1 2026 Chance of VFR at all terminals through 12Z is 95 percent. Chance of VFR at all terminals through 18Z is 90 percent. A small area of precipitation noted on radar moving across southwest Lower MI has resulted in reports of light rain at some terminals, including GRR. However, ceilings remain very high, greater than 8000 ft AGL, with significant sub-cloud evaporation, so precipitation accumulations will remain spotty and light. Some models, such as the HRRR, suggest that another batch of light showers could move northward into extreme southwest Lower MI, possibly affecting AZO/MKG/GRR with another round of light rain later this morning. However, this is a low probability, non- impactful event not worthy of mention in the TAFs. Precipitation is not expected this afternoon into tonight. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ DISCUSSION...TJT AVIATION...TJT

NWS GRR Office Area Forecast Discussion