Tuesday's Fresh Powder

Update 2:05pm: The batch of heaviest snow is moving through eastern Iowa right now. Expect snowfall rates to increase within the next few hours. Road conditions where snow has fallen already today are poor; KCRG-TV reports an eight-vehicle accident (including seven semis) has shut down a portion of Interstate 80 a bit east of Iowa City. Obviously, you should take it easy on your evening commute tonight!

Freeport just came in with a report of 1" of snow so far.

Update 11:20am: The lower levels of the atmosphere around the Stateline are still a little too dry for snow. Snowfall is lagging behind what's showing up on radar, but snow is now being reported in Dubuque and Moline, so it's not far off. Just about every observation site in Iowa is reporting light or moderate snow, and that will be the case for us starting in the next couple of hours and lasting into the nighttime hours. The evening commute will slow as we'll have had a few hours of snow by that time; most highways in Iowa are reported to be partially or mostly covered with snow already. Fortunately, this snow will be fluffy, so it will be easy to shovel. In addition, winds are still expected to be fairly light, so blowing snow won't be a big worry.

Original Post:
The 0z and 6z data from this morning's model runs confirm our beliefs on today's snowfall. We are still in for a widespread snow event mainly for this afternoon and the first half of this evening. The snow is about to cross the Mississippi River with the fluffy stuff reaching Winnebago County between 11am and noon. Some snow storms cause widely varying totals, but Mother Nature is all about equality with this one. Most locations will end up in the 3-6" slot.

I only expect about 1/4" of liquid to be received from today's storm, but with such a cold atmosphere snow to liquid ratio could range between 15:1 and 18:1. Using this ratio, 0.25" of liquid would yield 3.75 to 4.5" of snow.

Commuters will have a slow go later this afternoon and early this evening as snowpacked roadways take shape. Thankfully with this event our winds will remain light, meaning that visibilities should be manageable and drifting should be minimal. With our skies turning completely dry by midnight, snowplows will have several hours before sunrise on Wednesday to clear the roadways. Main arteries should be fine by Wednesday morning with a few lingering slippery spots on the less traveled paths. -ADAM