12:15 PM, Tuesday, December 30, 2014
This morning was probably the coldest morning for foothills locations, and tonight will likely be the coldest night for the lower elevations, especially river valleys. Occasional snow and ice crystals into this evening won’t amount to much more accumulation. The sun should continue to be dimly visible at times and won’t be enough to warm temperatures much more than the +1 to +7 range (maybe staying below zero in some foothills locations). There should be more sun on Wednesday as temperatures climb to the 20s.
The middle and upper atmosphere will begin to warm tonight, but because of clearing skies and radiational cooling, low spots like river valleys will probably drop into the minus teens. Other areas will probably drop into the -5 to -10 range in the early to middle part of the night. Toward morning the temperature may start to rise slowly, especially in and near the foothills.
Thursday and Friday will be warmer, but not really all that mild, and there is a good chance that many areas won’t quite make it to freezing on New Years Day. A cold upper level storm system over the desert southwest should move east across New Mexico on Thursday and Friday, likely bringing some light snow to southern Colorado, especially the mountains. There is a slight chance for some clouds and light snow in the Denver-Boulder area late on New Years Day, but it will probably stay dry.
12:00 noon, Monday, December 29, 2014
The frigid arctic cold will continue into Wednesday, and the snow is expected to continue into Tuesday evening, although it is likely to be lighter and intermittent on Tuesday.
I’m still expecting two-day storm total accumulations through Tuesday to be in the 3-6 inch range for the Front Range urban corridor and eastern plains. But 5-9 inches is a more likely range in the foothills and in some areas immediately along the foothills like Boulder, Golden, and the far south and southwest suburbs of Denver. The clouds might thin enough at times on Tuesday to make the sun dimly visible, but don’t expect that to add much to the maximum temperature!
Temperatures will continue to drop Monday and be near zero around nightfall. Minimum temperatures on Tuesday and Wednesday mornings are likely to be mainly in the -5 to -15 range. Wednesday morning may be slightly less cold than Tuesday in the foothills, but in the lower elevations, Wednesday may be the coldest morning, especially in river valleys. On Tuesday the maximum temperature will probably be within a few degrees of zero. Expect to get above 20 on Wednesday.
The record low for Denver and Boulder on Tuesday morning is -11, and there is a chance we will reach that. The record low for Denver Wednesday morning is -19 and for Boulder it’s -18, and there is less chance for reaching that.
One record that is likely to get shattered is the record low maximum temperature for Tuesday, which is 8 for Denver and a balmy 16 for Boulder.
New Year’s Day:
A large piece of this cold storm system will break off and move into the desert southwest bringing cold weather there too. It is expected to move eastward Thursday and there is a slight chance that it will be close enough to bring a little bit of clouds and light snow to the Front Range on New Years Day. There is a better chance across southern Colorado.
12:15 PM, Sunday, December 28, 2014
The final three days of 2014 will be very cold, mainly cloudy, and with snow (at least Mon-Tue). This is due to a storm system from the west and a strong arctic cold front from the north.
The cold front should move south through Wyoming overnight and southward through Colorado’s Front Range Monday morning, probably before daybreak in Denver and points north. Early morning temperatures on Monday are likely to be in the teens in the Denver to Fort Collins corridor and on the way down through the single digits in the afternoon and to around zero by nightfall. It may take a few hours longer from Colorado Springs and points south, but the day will turn very cold there too. On Tuesday, temperatures are likely to start in the -1 to -10 range and barely climb above zero during the day before falling to the -1 to -10 range Tuesday night (maybe around -15 in some valley areas and DIA). Wednesday is likely to see temperatures rise to the low 20s. We may even break the freezing mark on New Years Day.
Clouds and Snow:
Low stratus is likely to develop behind the cold front Monday morning and then it is expected to be mainly cloudy into Tuesday night. The clouds might thin a little at times in the high elevations on Tuesday. Periods of snow and ice crystals are likely Monday morning through Tuesday evening. During the period we are likely to see 3-6 inches, with 6-9 inches possible in the foothills and Palmer Divide area. The best chance for a period of moderate or heavy intensity snow along the Front Range is Monday afternoon and/or night, but most of the snowfall should be light. Mountain areas in western Colorado are likely to see 6-12 inches beginning today. The final remnant of the storm is probably going to pass south of Colorado on Thu-Fri and may bring more clouds and snow to the San Juans and/or Sangre deCristo ranges.
The record lows for Tue and Wed morning in Denver are -11 and -19, and in Boulder they are -11 and -18. There is a small chance we will reach the Tue record, but very little chance for the Wed record. The record lowest maximum temperature on Tue is +8 for Denver and +16 for Boulder. Both are likely to fall, and Boulder’s may get clobbered.
1:00 PM, Friday, December 26, 2014
Showery snow should linger through this evening and result in some light additional accumulation in some areas. Then the Front Range region should be drier Saturday and through the day on Sunday.
The next cold front, probably Sunday night, will bring very cold air from the arctic regions of Canada. It will get colder statewide, but most notably for the Front Range, eastern Colorado & Wyoming. Even in the lower elevations daytime temperatures are likely to remain below 20 Monday through Wednesday, and maybe below 10 on Tuesday. Morning low temperatures will probably dip below zero on the coldest morning (Tue and/or Wed).
It does not look like a heavy snow situation for the Front Range, but that can’t be ruled out yet. What does look likely is a long period with clouds and mainly light snow from Sunday night through Tuesday night that will probably add up to something in the 3-6 inch range.
The west slope is likely to see some mountain snow move back in on Sunday after a mainly dry day on Saturday, and then periods of snow during the early to midweek period.
7:00 AM, Christmas Day, 2014
I have not changed my forecast on snow amounts, but the arrival of the cold front and snow is a little faster than originally predicted. At 7AM the cold front has reached Cheyenne and should move south through the Colorado Front Range this morning. Snow is developing in the Cheyenne area and will probably spread into the northern Front Range this morning and the Denver-Boulder area in the early afternoon. Snow may be moderate or heavy at times late this afternoon and this evening so expect winter road conditions in the area.
This forecast amounts from my post last night:
7-12 inches: Nederland, Georgetown, Evergreen, Monument
5-8 inches: Cheyenne, Boulder, Broomfield, Denver (and the west and south suburbs)
3-6 inches: Fort Collins, Longmont, DIA, Colorado Springs
4:45 PM, Wednesday, December 24, 2014
It is still looking like a late-day white Christmas for the Front Range. Snow is likely to develop north-to-south from Cheyenne to Colorado Springs during the afternoon and early evening. Boulder and Denver will probably see snowfall begin mid to late afternoon. Accumulations should range from about 3 inches on the plains east and northeast of Denver, to 10 inches in some foothills locations west and southwest of Denver. Expect 6-10 inches in the mountains and high passes of western Colorado. Most of the Front Range snow will probably fall before noon on Friday, but intermittent light snow is likely to persist into Friday night.
Most likely amounts at given locations:
7-12 inches: Nederland, Georgetown, Evergreen, Monument.
5-8 inches: Cheyenne, Boulder, Broomfield, Denver (and its south and west suburbs).
3-6 inches: Fort Collins, Longmont, DIA, Colorado Springs
5:30 AM, Wednesday, December 24, 2014
I won’t be able to update during the day today, but here is what the latest is…
A storm system late on Christmas Day will likely organize as a four-conrers low, a term that some weather enthusiasts are familiar with as it relates to Front Range snow. After a mild start to Christmas Day a cold front should sweep down the Front Range during the afternoon. Snow is likely to develop in the mid afternoon to early evening period. With falling temperatures and the possibility of some brief moderate to heavy snowfall rates, road conditions may deteriorate rapidly near or after nightfall on Christmas (could be during the afternoon in Cheyenne).
Expect 3-6 inches through much of the area by midday Friday, and probably 5-8 inches in some places in and very close to the foothills and Palmer Divide. Light snow and clouds may linger into Saturday morning. Accumulation should be lighter out on the high plains, but blowing snow will likely be a hazard there. To the west, winter travel conditions are likely to develop on Christmas Day, especially at the passes.
It still looks like a multi-day cold wave next week, possibly beginning Sunday night or early Monday. We could see some days with high temperatures below 20 and lows below zero.