A deep trough across the west is providing southwesterly flow across the midwest with several shortwaves riding along the path. The first is currently moving across Iowa tonight and will impact the state through the overnight and morning hours in the form of a wintry mix with snow in the northwest with a mix in the north central and northeastern portions. The radar as of 11:30 p.m. shows a large area of snow in the northwestern quarter of the state, with the heaviest in the west central. However, much of this is not reaching the ground, as evident by airport observations. The only locations reporting precipitation at this time would be at Sioux City, Sioux Falls, and Des Moines, where light snow is being reported; Harlan and Tekamah, where unknown precipitation is falling (typically a wintry mix); and Omaha, where light rain is falling. Beyond the border, light snow is being reported at airports across southern Minnesota, southeastern South Dakota, and northern Nebraska, with heavy snow in Windom. Much of the precipitation south of the Interstate 80 corridor should remain as rain for the time being.
As the night goes on and the atmosphere saturates, precipitation should increase in intensity and we should see precipitation falling across much of the warning area. One of the big wild cards overnight is what form of precipitation things will fall as. Across the northwest, temperatures are cold far enough into the atmosphere to where things should fall as primarily shown. This is where the heavier snow accumulation will fall, along the lines of three-to-five inches in areas such as Sheldon, Rock Rapids, etc., with one-to-three inches east of that from Algona to Sac City to Onawa. Farther east, it’s a bit warmer for the precipitation to fall as a freezing rain or mixed bag. This mixed bag will primarily exist east of the Highway 169 corridor and north of Highway 30. It will have to be monitored on how far south this mixed bag goes as the temperatures have been in question all day. The end result of this should be around a 0.01 to 0.05″ of ice and potentially up to an inch of snow. Again, these totals will fluctuate, depending on the precipitation type.
Things should continue into tomorrow morning before precipitation gradually lessens during the afternoon hours. The Winter Storm (Snow) Warning for Lyon county and Winter Weather (Snow and Blowing Snow) Advisory for northwest Iowa runs until 6:00 p.m., while the Winter Weather Advisory (Freezing Rain and Light Snow) runs until 12:00 p.m. Nonetheless, expect travel impacted across much of the state into the early evening hours. It’s also worth noting that another weak shortwave may approach the area tomorrow night causing icy roads and travel difficulties across the southern end of the state.
Sunday will be much nicer with sunshine across much of the state with highs, albeit cold, in the teens northwest to 30s south. Another significant weather system is expected early next week, see an upcoming post for more information on that.
Stay tuned to the Iowa Weather Network for the latest information!