Winter Storm: Dec. 10-11 -- Update #2

Afternoon Update: Models from this morning went slightly warmer, or at least the WRF went warmer to become more in line with the GFS as far as snowfall production went. Looked over several of the atmospheric profiles this afternoon with several other meteorology students here at Iowa State and the consensus seems to be that this is a challenging forecast on precip type. Any slight changes in the temperatures anywhere below 700mb is likely to results in different precip types. The forecast from this morning still seems to be going fairly well, the location and timing of the system still seems to be good. One likely change will be to include the snow & sleet accumulations together; read snow/sleet accumulations of 2-6 inches combined. The center area will also likely see anywhere from a tenth of quarter of an inch of ice as well before the sleet/snow begin Tuesday morning. Of course as you reach further north/west to the line expect only 2 inches of sleet/snow with little ice accumulation. The south/eastern portion of the state still seems likely to have dramatic ice accumulations, with some forecasts indicating over an inch of ice accumulations. Therefore storyline of significant winter storm still going, areas of Oklahoma already saw some significant ice before it turned to rain this morning. Expect the remainder of the plains to get into the action by tomorrow morning...

Morning Forecast: Upgrades from the winter storm watch are continuing this morning, areas of southeastern Iowa are now in a Ice Storm Warning, other areas of southern Iowa are in a Winter Storm Warning and just to the north and east of that will likely be a Winter Weather Advisory. Cities under the Ice Storm Warning include Lamoni, Ottumwa, Davenport, Burlington and Keokuk. Those cities are expected to receive a half inch to over an inch of damaging ice accumulation, beginning tonight and lasting into Tuesday before a change to a sleet/snow mix may occur late Tuesday afternoon. The Winter Storm Warning includes Omaha, Atlantic, Des Moines, Ames, Marshalltown, Cedar Rapids & Iowa City. Areas within this stretch of the storm are expected to incur some freezing rain and/or sleet tonight before a change over to snow occurs Tuesday morning. These areas could receive up to a third of an inch of freezing rain, or one-half to an inch of sleet accumulations during the overnight. By Tuesday, the snow could accumulate from around an inch to upwards of 5 inches! The Winter Weather Advisory has been issued for portions of the state further north, more counties are expected to be included later this morning. These areas may receive some light ice/sleet accumulations before seeing all snow by Tuesday; total snow accumulations still likely into the 2-5 inch range.

For the latest map on the advisories/warnings, check out the Des Moines Winter Storm Page. A rough map of my current forecast is below: