015 FXUS63 KGRR 111906 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 206 PM EST Wed Nov 11 2026 .KEY MESSAGES... - Light rain possible today - Cooler Thursday, lake shore rain/snow showers through Saturday && .DISCUSSION... Issued at 206 PM EST Wed Nov 11 2026 - Light rain possible today/tonight Water vapor imagery shows a short wave in western IL being nudged eastward by another short wave dropping south across northwest IA within a deepening upper trough. The IL short wave is producing light rain across the northern half of the cwa, with much more sparsely populated echos south of I-96. A wider radar view shows more showers/storms moving across northern IL. Model trends point toward the IL thunder remaining south of the cwa. All of the precipitation tonight will be light rain. - Cooler Thursday, lake shore rain/snow showers through Saturday The IA short wave will drag down colder air tomorrow as it pivots through the upper trough. H8 temperatures near +2c today will fall to -7c Thursday. The north flow that will be generated by the short wave will coupled with the cold advection will produce lake effect rain showers mostly over the lake, but clipping the lake shore too. While boundary layer air will be too warm for snow Thursday, that could change Thursday night as the temperature drops. If any snow does develop Thursday night, the lake shore north of Whitehall has the highest chance of seeing it. That area could potentially see a few tenths of an inch of snow. The bulk of the precipitation will be just west of the lake shore falling over the lake. The upper trough will remain over the state through Saturday before beginning to lift northeastward. The colder air will remain too with h8 temps in the -6c to -8c range through the weekend. That will produce surface temperatures in the mid 40s for highs through Monday before the trough moves east and then ridging noses into the region. At that point highs will climb into the 50s early/mid week. && .AVIATION /18Z TAFS THROUGH 18Z THURSDAY/... Issued at 1248 PM EST Wed Nov 11 2026 Low level clouds and fog have finally dissipated and we are now seeing a west-east band of light rain roughly along a Whitehall to White Cloud line. Cloud bases around there are in the 4000-5000 foot AGL range and surface observations indicate weak convergence along this axis. The band has been tightening somewhat, suggesting that some lower tropospheric deformation/fgen forcing is coupled with the surface convergence. Even with all of this favorable forcing for ascent, only light rain is being reported thus far; this is not surprising given the very dry sub-cloud layer observed in the local 12Z raobs. This precipitation feature will be the thing to watch between now and 00Z because some guidance such as the HRRR keeps the band organized and drifting south towards the MKG and GRR terminals later today. Even if this occurs, there is a good chance that VFR conditions will hold at those locations. The worst expected scenario at this point would be ceilings approaching 3000 ft AGL. MVFR ceilings do look more likely areawide after 03Z and particularly after 06Z as the atmosphere moistens from the top down. Fuel alternate ceilings are also possible after 06Z, estimated at around 70 percent chance. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...Small Craft Advisory from 7 PM this evening to 7 PM EST Friday for LMZ844>849. && $$ DISCUSSION...04 AVIATION...TJT

NWS GRR Office Area Forecast Discussion