142 FXUS63 KGRR 241956 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 256 PM EST Wed Dec 24 2025 .KEY MESSAGES... - Some drizzle/light rain for SW areas tonight - Period of impactful freezing rain likely late Thu Night/Fri - Warm with rain Sat night changing to cold and snow late Sun && .DISCUSSION... Issued at 256 PM EST Wed Dec 24 2025 - Some drizzle/light rain for SW areas tonight High clouds have dominated the skies today over SW Lower. High pressure at the sfc is departing the area this afternoon. We continue to focus initially on a wave that will be coming out from the Central Plains and moving across Central Indiana tonight. The trend for this system is to be a tad further south compared to yesterday, and moisture to be even more shallow for our area here. Forecast soundings and cross-sections show moisture now only topping off up around 7k ft with quite a bit of dry air up to around 15-20k ft. With no real instability to be had, it will be tough to get much more than drizzle out of this pcpn for us tonight. The low level moisture stays above 0C, so no dgz saturation. We do expect that the vast majority of the area that has the drizzle chances tonight will stay just above freezing. There is a small chance that the northern edge of the drizzle might be just a tad below freezing, and it would be freezing drizzle. The likelihood of this is quite low. - Period of impactful freezing rain likely late Thu Night/Fri The system zipping by to our south tonight will move far enough away that we will see ridging build in for most of the daylight hours on Christmas(Thursday) The low level flow of dry and cooler air will likely bring at least some breaks in the clouds during the heart of the day. The next system poised to move into the region continues to look like a somewhat phased system with a srn stream waves, and the southern edge of a northern stream wave. Not a lot of moisture associated with these systems, but the forcing will compensate a bit. There is some warmer air trying to move up via a 30+ knot low level jet ahead of this system. This warm air advection aloft, overriding the cool and drier air toward the sfc with the flow having been from the east, continues to support a period of freezing rain very late Thursday night through mid-afternoon Friday. At this juncture, this looks like a solid advisory type of event for most of the area (less than 0.25"), with maybe a small chance (~30%) of some minimal warning criteria. There are a few reasons for the high confidence that this is going to be an advisory type of event. The speed of the system does not favor higher ice amounts. While ensemble mean qpf looks to be between a quarter and four tenths of an inch, ice accumulation is usually not a 1:1 ratio. This is due to run off with higher rainfall rates and latent heat with rain dropping from a thick layer of the atmosphere around +6C not allowing it to all freeze immediately. There are some locally higher bands, but any higher rainfall rates will not freeze efficiently on sfcs like roads. In addition to the expected ice amounts, winds are not going to be making the situation much worse during the ice period. It will be a little breezy, but this should not cause a lot of extra issues. We will see the ice gradually change to rain, and end from west to east late Friday morning through mid-afternoon. We still have some time to fine tune the forecast amounts, however this scenario has been fairly consistent run to run for the past couple of days. That leads to increased confidence of our thinking. We will obviously still watch for the potential of increased amounts, and resulting headline decisions. - Warm with rain Sat night changing to cold and snow late Sun We will see a break in the weather then from late Friday afternoon through most of the daylight hours on Saturday. A nice ridge will traverse the area during this time frame. It will take until Saturday evening now for the next system to get close enough to bring the next chance of precipitation. We will be seeing more of a deep flow from the SW as a large long wave trough comes onshore over the Pacific NW. Ahead of this long wave trough will be a short wave over the Desert SW that lifts up to the NE ahead of it. The trend has been for the long wave trough to be slower, and allow any precipitation be rain now through much of Sunday. There is a bit of uncertainty whether we see a direct hit from the leading short wave. The timing all depends on the interaction of the long and short waves. What we do know though is the long wave with the colder air will make it through the area by Monday. The cyclonic part of the jet crosses across the area Sunday evening, and moves out Monday afternoon. This does not look like a big lake effect event due to the short nature of it. We continue to watch additional strong jet energy dive southward from the Arctic around the New Years Eve/Day time frame. This looks to bring another shot of precipitation with it, and colder air behind it. Too many small details have to be worked out with that at this time. && .AVIATION /18Z TAFS THROUGH 18Z THURSDAY/... Issued at 1248 PM EST Wed Dec 24 2025 VFR conditions will continue through 00Z then MVFR can be expected overnight into Thursday morning. There is a chance for drizzle this evening and overnight across southern Lower Michigan, but the chance of icing on runway surfaces is less than 10 percent. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ DISCUSSION...NJJ AVIATION...Ostuno

NWS GRR Office Area Forecast Discussion