1:15 PM, Tuesday, December 13,2016
It looks like we may be in for a cold weekend statewide with maybe a little snow in the early part of the weekend. I will update later in the week, but right now it looks like temperatures may run about 20-25 degrees below average Saturday and Sunday.
It will be a little colder tomorrow with temperatures staying below freezing all day. Expect a light accumulation of snow in the mountains as well as up near the Colorado-Wyoming border and in the Cheyenne area. But most of the Front Range urban corridor should see little or no snow.
After a cold start Thursday we will probably see temperatures climb to around 50, and the mildness should continue into at least part of Friday. It may get a bit windy in spots along the foothills.
Much colder beginning late Friday. Some significant snow is likely in the mountains beginning Friday. For the foothills and plains of the Front Range the snow forecast is still uncertain. But at least some light snow accumulations appear likely Friday evening into Saturday morning.
3:00 PM, Friday, December 9, 2016
Foothills and Plains
The first Chinook setup of the season will be with us Friday night through Saturday night. Milder temperatures may be accompanied by occasional periods with strong gusty winds. There may be some gusts exceeding 60 mph in and near the foothills, including the west suburbs of Denver and the Boulder area. It should not be continuously windy.
On Sunday there should be less wind and a little colder with more cloudy intervals and maybe some flurries or light snow. Little or no accumulation is expected for most areas. But there may be some west-east bands of snow that result in about an inch in a subset of the region.
Expect a blustery weekend in the mountains. 6-12 inches of snow is probable at high elevations along and west of the continental divide. The snow may extend about 10 miles east of the continental divide at times causing some lighter accumulations there. So there should be fresh snow but a bitter wind chill at times at places like Brainard Lake, Eldora, and Loveland Pass.
6:05 am, Tuesday, December 6, 2016
It still looks like 2-5 inches of snow this evening through Wednesday morning, maybe 6 or a little more in the higher elevations. Very cold temperatures will be in place through Thursday. The snow should be the fluffy, low-moisture kind.
Timing & Intensity
Snow is likely to begin in the late afternoon or early evening today. Although we might get through the evening commute without much problem, you should be prepared for a snowy drive. Wednesday morning should see a snowy commute. Snow is likely to become more scattered as the clouds begin to break up during the day Wednesday.
Snow should be mainly light intensity but there may be a few moderate-intensity periods associate with narrow bands oriented southwest-northeast.
Many areas should rise above 20 today, but it may begin to turn colder with increasing clouds in the afternoon. Expect single digits tonight and only the teens Wednesday. Most areas are likely to be in the 0 to -5 range Thursday morning, with some cold spots getting down to the -5 to -10 range. Temperatures should climb above freezing on Friday.
3:55 PM, Sunday, December 4, 2016
The beginnings of a cold few days will start Monday afternoon, and then very cold with some snow likely Tuesday afternoon into Wednesday.
It may still be rather mild Monday morning, but don’t be fooled. A cold front will move down the Front Range from Cheyenne to Colorado Springs and temperatures will fall and not likely reach above freezing again until late in the week. Temperatures on Tuesday will likely not get out of the 20s even in the lower elevations, and it may start turning even colder by afternoon. Wednesday will likely stay below 20 at all elevations.
Wednesday and Thursday mornings will be very cold with single digits Wednesday and around zero on Thursday in the lower elevations. If we get clear skies over fresh snow cover Thursday morning I would expect to see many locations slip below zero. At the Boulder climate station +3 on January 1st is the coldest so far in 2016 (an atypically warm reading for an annual low), so we may get a more typical annual min yet!
Some scattered light snow may accompany the first push of cold air late Monday into Tuesday with light accumulations in the mountains and little or nothing in the lower foothills and plains. This is the kind of setup that sometimes leads to freezing drizzle along the Front Range, but with low moisture values across the high plains we may be on the edge of forming freezing drizzle and fog.
The second push of colder air will be accompanied by Pacific moisture in the mid levels and maybe deeper upslope too. So snow is likely late Tuesday into early Wednesday. At this time it looks like relatively light amounts, 2-5 inches, probably topping 6 in a few locations in the mountains. I will be watching for the small possibility that a mid level circulation will develop and increase the snow potential, but that does not appear likely right now.
9:25 AM, Friday, December 2, 2016
A weak storm system is passing mainly to the south of Colorado today, but it is managing to generate radar returns over the Front Range (moving up from the south). Some of what the radar is sensing is evaporating before reaching the ground. Even with the sub-cloud dryness, it appears that much of the Front Range region will see flurries, and maybe a few more moderate snow showers in some local spots. Accumulation through this evening should range from zero or dusting (many areas) to 1 inch in a few spots.
Expect a dry weekend with cold mornings but probably a bit milder by Sunday with low elevations temperatures approaching 50. Don’t get used to it.
What may be the coldest air mass so far this season is likely to start moving into the Front Range region late Monday and keep temperatures below freezing all day Tuesday and Wednesday. Snow? Two reliable models, the American GFS and the European ECMWF suggest different scenarios. The GFS does not create a strong polar trough in the west and therefore never develops much low-level easterly (upslope) flow into the Front Range. Result, colder Tue-Wed, but with very limited moisture. The European Center model has been consistent with a polar trough in the West thus raising the odds of a significant snow into Colorado (mainly Tuesday). At this time I don’t feel that one solution is more reliable than the other, but I will note that the drier solution of the GFS would be more consistent with the pattern of the last 3-4 months. I will be updating this weekend.