Winter Storm: Dec. 1-2 -- Final Forecast & Links

Final Forecast: Models tonight still in astounding agreement with not only total precip, but even timing. Low pressure track is still slightly variable, however the warm air and its' progress seems to be in fairly good alignment. Given this case, will still likely side towards the WRF and its' solution given it has better resolution for the shallow warm layers that will take place. The GFS has also been extremely aggressive with warm air advection; and seemingly trying to pull near 60 degree temps into southern Iowa. That is not likely to happen and thus makes me lean a little more away from that kind of solution...

Looking at model initialization, current surface plots have the low at 998mb along the WY/CO border; neither model has anything close to that. Pressure falls currently show strong tendencies of moving this low to the east or northeast; potentially this storm moving a big quicker? Or further north compared to model forecasts? This is going to be very hard to tell and will likely just need to be watched to see what takes place. Either way, need to make a forecast off of it:

Essentially for my final forecast I'm going to list some cities and make the detailed forecast for them. In the end we can see how close I came, others in the area reading this can make comments as well to let me know how close I came. Once again, areas north of highway 30 under a Winter Storm Warning while areas along and south in an Ice Storm Warning.

Sioux Falls, SD: Precipitation likely beginning ~7 AM in the morning as snow, snow should last throughout the afternoon hours with some moderate to heavy snow possible. By mid-afternoon however, some sleet and/or ice pellets may begin to fall with accumulations possible. Snow totals of 4-7 inches & up to another quarter of an inch of sleet/ice pellets and possibly freezing rain before the storm winds down Saturday night.

Sioux City, IA: Snow beginning by 7 AM as well here, however this will be changing over to freezing rain by Noon and to rain by Saturday evening; a couple hours of rain may then switch back over to freezing rain and a bit more snow by Sunday morning. Total snow accumulation of 2-5", freezing rain and IP/sleet accumulation of a quarter of an inch.

Omaha, NE: Beginning as freezing rain from the beginning on Saturday morning, however changing over to rain just before Noon. Likely to stay as rain, with maybe a final glaze of ice before the storm ends Saturday night. Total ice accumulation of a third to half an inch; liquid rain near another third to half an inch.

Spencer, IA: Snow during the morning hours, turning over to ice pellets/sleet during the early afternoon hours with the potential for freezing rain as well into the evening. A light snow may occur before the storm ends Saturday night; total snow accumulation of 3-5 inches with ice/sleet accumulations of over a half inch possible.

Carroll, IA: Ice pellets or sleet to begin in the morning, turning to freezing rain and then rain during the early afternoon hours. Rain may likely finish this storm off, a few sleet or ice pellets may accompany it however. Around a half inch of some form of frozen precip; another half inch of liquid rain possible.

Creston, IA: Freezing rain turning to rain is the story once again, up to 6 hours of freezing rain before the rain in the afternoon. Around a third of an inch of ice, followed by ~.5 inches of rain.

Mason City, IA: Snow in the morning hours turning to freezing rain before Noon; some rain seems possible although dependent on ground and ice temp as well as the rain it may just freeze on the surface as well. Total ice accumulation of a half inch to two-thirds of an inch; a tenth of an inch of other forms of precipitation (rain, ice pellts & sleet).

Ames, IA: A bit of snow before freezing rain begins in the morning, the switch to rain seems to occur around supper-time. Rain likely throughout the nighttime hours with total liquid rain totals of a quarter to third of an inch. Ice accumulation of near a half inch with some accumulation of snow and/or ice pellets as well.

Des Moines, IA: Much the same as Ames, with a bit of snow followed by several hours of freezing rain. Rain change over seems to occur in the late afternoon, total rain accumulation of a third to half inch. Total ice accumulation between a third and half inch as well.

Ottumwa, IA: Some snow, ice pellets/sleet then freezing rain by Noon, holding off the rain until mid-afternoon. Near a half an inch of frozen precipitation, a quarter to third of an inch of rain with precip ending around sunrise Sunday.

LaCrosse, WI: Snowfall likely by Noon tomorrow, turning to ice pellets/sleet by evening and some rain by the overnight. Total snow accumulation of 2-5 inches, ice accumulations up to a half inch; various other frozen precip types may total up to another quarter of an inch.

Waterloo, IA: Some snow or ice pellets during the late morning hours before freezing rain takes over for the afternoon/evening. Rain may work its' way in during the overnight, rain total near a tenth of an inch. Ice accumulations may be hefty, looking at a half inch to near three-quarters of an inch. Snowfall accumulation likely an inch or less by the time the storm ends Sunday morning.

Dubuque, IA: Saturday afternoon expect ice pellets or sleet turning to freezing rain for a majority of the time. Some rain likely to mix in during the overnight hours, totaling a quarter of an inch. Ice accumulations over a half inch seem likely, with near three-quarters of an inch possible!

Davenport, IA: Snow to freezing rain expected by Noon, holding off any precip type change until sunset when it turns over to rain. Expect light rain to occur for much of the night, finishing off Sunday afternoon with a small shot at frz rain or snow. Total ice accumulation of near or over a half an inch possible, rainfall near a quarter of an inch.

Cedar Rapids, IA: The mix of snow/ice and sleet for the late morning and early afternoon, likely staying freezing rain until later afternoon. A total of a half inch or higher of ice accumulation; approx. a quarter inch of rain as things come to an end by Noon on Sunday.

Burlington, IA: Early snow before turning to freezing rain by Noon on Saturday, likely to stay that way until later afternoon. Total ice accumulation of a quarter to third of an inch; rain totals near a quarter of an inch as well. Precipitation likely to taper off by Sunday afternoon.

Updates likely throughout the day tomorrow as I receive information and check out the current conditions around the state. Be sure to check road conditions and the latest updates on your forecast before heading out anywhere, I'm sure by the afternoon tomorrow that travel will not be advised. First potentially dangerous winter storms, with all the makings for possible widespread damage if conditions do fall into place.


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8:45 PM Update: I've updated the frame on the right of the blog posts to contain several links that may be of interest to people within this storm. The Surface Plots are simply a map that has the plots for the weather stations, information shown include winds, temperature/dewpoints and current weather with cloud cover. The Iowa Road Conditions is just that, the current road conditions for the state of Iowa as updated by the Iowa DOT. The IEM Freeze is an exceptionally good tool for freezing rain conditions, it overlays the current radar image with air temperatures (numbers) and pavement temperatures (dots). The Iowa weather round-up is a text version of the station plots in case you would like to read instead of interpret. The Iowa Watches/Warnings/Advisories link contains the texts to all of the issuances for Des Moines NWS and all surrounding, please search your county name to find ones of interest. Lastly, local storm reports will be updated by the NWS offices as they receive them during the storm; NWS office codes are within parentheses.