A messy forecast is order for the next 24-to-48 hours as a storm system sets it’s eyes on affecting the area. Already impacts can be seen by looking at the radar loop with a mix between ice, sleet, snow, rain, and even thunderstorms in southeast Iowa. This activity will continue to overspread the area over the next couple of hours with the precipitation type changing as the atmosphere battles with dry northeasterly air and moist southerly air. This will fluctuate the freezing line at all levels across the state and continue to change the precipitation type.
By later tonight, precipitation should push northward with a gradual transition to all snow by morning. The end result of the mixed precipitation overnight will be a glaze of ice across much of the state… nearing over a quarter inch in some areas, primarily stretching from west central and southwestern Iowa to north central Iowa. While the highest amounts on the map below is 0.1 to 0.25 inches, locally higher amounts above that will be possible. This will create treacherous travel overnight across the state, and this is before the bulk of the snow has even began.
As mentioned above, light snow should be overspreading much of the area. This snow will be a wet, moist snow – not a dry one. While this helps keep the blowing snow potential to a minimum for a while, this does not help the travel situation. A continual light snow on top of glazed roads will make travel Monday morning hazardous across the state. This will only get worse as the day goes on as the snow intensifies and gets heavier as the afternoon rolls around and only makes the travel situation worse. Patchy blowing snow will also be possible with wind gusts to 15-20 MPH. Light snow will continue into the overnight hours on Monday and likely into the Tuesday morning commute. I would not be surprised to see several delays on Tuesday morning for this reason. Blowing snow will also be a heightened hazard as the wind picks up late Monday night.
The end result of this will cause a variety of snowfall totals across the area. It’s important to note that gradients are not perfect and they never turn out to be as smooth as they appear. Totals will locally higher in some spots and will vary from point-to-point. The highest totals will be in northwest Iowa where the bulk of the snow is expected to be and where the transition will happen the quickest. Eight-to-ten inches of snow is expected here, including Sheldon, Spencer, Estherville, and Sioux City, with locally higher amounts possible. Outside of this, the cut off line for snow will be very sharp, potentially more than what we have depicted on the map. Six-to-eight inches will be possible on the outside of this, including Garner, Fort Dodge, Carroll, Denison, and Algona. Four-to-six inches will be sharply cut-off beyond this with 2-4″ behind that, including the Des Moines metro. The trace-to-two inch area is up in the air overall, as this could be farther west or east than originally predicted. Much of eastern Iowa will likely end up with a glazing of ice or snow nonetheless.
A Winter Storm Warning has been issued for the heavy snow and freezing rain threat and an Winter Weather Advisory outside of this for the lesser threat. The vast majority of these will go in effect late tonight and last into late Tuesday or Wednesday (except for the southern end where it’s shorter). For the exact specifics on these alerts, please visit your local forecast page on the NWS website.
