NZUS93 KMPX 011951 LLLMPX Preliminary Local Storm Report National Weather Service Twin Cities/Chanhassen MN 251 PM CDT Tue Apr 1 2025 ...AFD... Today through Wednesday…It may be April 1st but this is a legitimate winter storm system. A potent late season winter storm system will bring widespread precipitation to the Upper Midwest today, with periods of rain and snow expected. The heaviest snow is anticipated in central Minnesota this afternoon and evening, transitioning to rain by Wednesday morning as the system departs east into the Great Lakes. This system will bring two rounds of precipitation with a lull in between. The first comes in the form of an impressive warm air advection driven band that’ll form along the MN/IA border and lift northward through the evening hours. Latest trends suggest a few hours of moderate to heavy snowfall associated with this feature. This impressive FGEN band has been getting picked up within guidance for the last several runs, even in global models, so confidence is high that we’ll see it form and lift northward. What’s less confident is how much falls as snow AND what accumulates. April isn’t the best time of year for snowfall events to hit the high-end marks and overachieve but that doesn’t mean we can’t get a good thump! The latest hi-res guidance matches more closely with the latest observations that would support more snow for locations like the Twin Cities metro, though the forecast soundings reveal temperature profiles are as razor thin as physics will allow. This means we’ll likely see a very wet snow that’ll struggle to accumulate until the heavier rates arrive this evening - which could make matters worse as the sun sets and we lose our diurnal heating. This scenario means we could see travel impacts as far south as the Twin Cities metro if we’re able to maintain heavier snowfall rates later today. On Wednesday, we’ll see the low track just south of the Minnesota/Iowa line. This does keep us on the northern/cold side of the system, but strong low level WAA will mean rain will be the dominant p-type in some areas, particularly southern/eastern Minnesota and western Wisconsin. The areas with the best chance to see 4 to 6+ inches of snow will be along the 700mb low track over west-central Minnesota. Our Western/central Minnesota counties where snow is more likely throughout the entirety of this system. Our temperature profile will continue to add complexity, as slight variations could shift precipitation from snow to rain, especially in marginal areas in our Winter Weather Advisory. Potential snowfall accumulations remain a key concern as referred to above. Guidance spread is still frustratingly significant given the event is currently unfolding across the region. For the Twin Cities, the latest guidance would bring 1-2 inches of wet snow that falls in a span of a couple of hours this evening with accumulations mainly on grassy surfaces. On the high-end we could see 2-4 inches on grassy areas, but that would mean a lot would have to come together for that to be a reality. Regardless, some travel impacts may unfold, especially over central Minnesota, where snow & temperatures remain more favorable. Travel impacts will increase through the evening hours with strong support for snowfall rates exceeding 0.5 inch per hour, which will overwhelm the warm ground/pavement temperatures and could lead to slippery conditions. In central Minnesota, where warnings are in effect, heavier accumulations are likely, potentially reaching 4-6+ inches by Wednesday afternoon, but there is still some uncertainty with where the deformation band sets up on Wednesday. Latest guidance would place that band over west-central Minnesota and that means we could see snowfall totals trend higher in these locations. What impacts shake out will be difficult to predict given the several uncertain variables, but we’ve seen impactful snow events deeper into April and even early May. Snow to liquid ratios will be quite low, on the 7 to 9:1 range given the marginal snow profiles observed in forecast soundings. Our headlines highlight a Winter Storm Warning for our central Minnesota counties of Douglas county to Kanabec county. These counties have the highest probability of receiving 6+ inches of snowfall by Wednesday evening. Elsewhere, a Winter Weather Advisory is in effect for portions of western Minnesota, central Minnesota, and western Wisconsin. These locations will likely see a few inches of snow this evening through Wednesday morning. These locations also have the highest uncertainty where subtle shifts in track or slightly colder or warmer air temperatures could break the current forecast. Additional headline changes cannot be ruled out as this event begins to unfold across the region. Thursday through Tuesday, quiet weather with near-normal temperatures, with highs in the mid 40s to low 50s and lows in the low 20s and 30s for the first week of April, compared to normal highs in the 50s. The active weather pattern finally begins quiet down as an impressive rex block forms over the western CONUS, allowing dry conditions through early next week. Overall, a much less active pattern will take over and more typical Spring weather will be on tap && $$