Monthly Archives: December 2019

New Year’s Day: snow mountains, dry eastern foothills and plains

12:15 PM MST, Tuesday, December 31, 2019

A moist Pacific storm will move west-to-east across the central Rockies on New Years Day, and maybe another at the start of next week. That’s good news for those who like snow in the mountains. Winter travel should be expected Wednesday and Wednesday night at the high passes and west-facing slopes, especially north of I-70 where over a foot of snow is likely.

 

For the eastern foothills and plains the weather should be a bit milder on New Years Day, with maybe some areas of gusty winds near the foothills. January is the peak month for chinook windstorms. Tomorrow does not look like a classic setup, but I am watching for possible windy conditions this coming weekend.

Saturday snow potential increasing

7:45 PM MST, Friday, December 27, 2019

Here’s a quick update to what I wrote earlier today. Satellite imagery and the evening runs of the mesoscale models have increased the chances for a 6-inch snowfall in the Denver metro area (including DIA and Boulder) for late tonight and Saturday (there is a smaller chance for that much in Longmont, Lyons and Fort Collins). Be prepared for a snowy, cold Saturday.

Some snow this afternoon/evening; some more Saturday

12:00 Noon MST, Friday, December 27, 2019

A cold upper level trof is moving through the region today and Saturday. The surface storm is likely to move from the Southwest to Nebraska as it intensifies between now and Saturday night. For eastern Colorado there will probably be snow (will lull periods) from mid afternoon through Saturday. The action on Saturday will likely shift to northeastern Colorado (mainly north of Colorado Springs).

 

This afternoon and early evening:

Areas of heavy snow have been impacting the mountains of southern Colorado and northern New Mexico, and there is even some lightning and thunder reported not too far from Santa Fe. An area of snow is probably going to move from south-to-north through the Front Range urban corridor from mid afternoon to mid evening. It’s not a solid area, so accumulation is likely to range from nothing to around a half-inch for Denver-Boulder-Fort Collins-Cheyenne. Out toward the Nebraska and Kansas border there may be several inches in a short time, and some freezing rain near the Kansas border.

  • through 9PM
    • Denver-Boulder-Fort Collins, Cheyenne: 0-0.5 inch
    • Colorado Springs: 1-3 inches
    • far northeastern plains 1-4 inches (some freezing rain along I-70 near the Kansas border)

Tonight and Saturday

The action will likely shift to the Front Range and high plains from Jefferson & Douglas counties northward by Saturday morning. There may be some long lull periods, but 0.5 to 4 inches seems to be the most likely snowfall for Denver-Boulder-Fort Collins late tonight and Saturday.

  • after 9PM Friday through Saturday
    • Castle Rock-Denver-Boulder-Longmont-Fort Collins: 0.5-4″
    • Cheyenne: 3-5″
    • Colorado Springs: less than 1″
  • In and near the foothills won’t necessarily have the most snow
  • Areas of heavy snow (more than 6″) and blowing snow are possible in far northeastern Colorado, western Nebraska, and in Wyoming east of Cheyenne.

Colder, some snow uncertainty Saturday

3:00 PM MST, Thursday, December 26, 2019

The next storm system for Colorado is likely to be in 2 pieces Friday and Saturday as it moves from Arizona to Nebraska. Most of the reliable model guidance suggests heavy snow will occur tomorrow in the San Juan mountains of southwestern Colorado (more than 12″). More modest amounts (4-8 inches) are likely across the southern Colorado foothills (mainly south of Colorado Springs) Friday night, and then spread to the northeastern plains (mainly east of Denver) on Saturday. Minor amounts are most likely in the Denver-Boulder-Fort Collins region.

Uncertainty for Denver-Boulder-Fort Collins

Although the scenario above is what most of our weather model guidance suggests, there is one notable exception. The GFS model forecasts that the more significant snowfall on Saturday will be a little farther west into the Denver-Boulder area. Since the GFS is the odd one out, that possibility is low, but it is possible. I will update tomorrow.

Christmas week forecast update

12:30 PM MST, Tuesday, December 24, 2019

Lots of Pacific moisture over the last few days have produced high clouds, but little or no precipitation in the central Rockies. A more impressive area of Pacific moisture late Christmas Day and overnight will increase the likelihood of snow in the mountains and west, but the chances are still small for the eastern foothills and plains. A colder air mass late Friday and Saturday will bring the next chance for snow.

 

Mountains and West Slope

Expect 4-10″ at the high mountain passes and west-facing slopes, mainly Christmas afternoon and night. Another round of snow might arrive Friday afternoon, mainly for the southern Colorado mountains.

 

Front Range foothills and plains

There is a small chance for showery precipitation (snow or rain & snow) late Christmas Day or night, but the chance for accumulation is only about 10% in any one location. Temperatures should be cooler, but still average to above-average through Thursday.

 

On Friday there is a good chance for some snow in southeastern Colorado, mainly south of Colorado Springs. A cold front on Friday evening or Saturday morning will bring a chance for more widespread light snow. It is looking like the temperatures by Saturday and Sunday are likely to be a little below average for the first time in a while.

 

 

Mild solstice weekend, colder by Christmas

11:30 AM MST, Friday, December 20, 2019

The winter solstice is at 9:19 PM MST on Saturday, December 21st, but the weather this weekend will hardly be wintry. Dry weather with above average temperatures should be around through at least Monday. The Front Range urban corridor should get into the 50s, and maybe 60 during the days. There may be some high level cirrus clouds from time to time.

 

For Tuesday-Thursday there is a lot of Pacific storm action to the west of Colorado. But winds at most levels should have a westerly component, so precipitation in the eastern foothills and plains appears unlikely, and the chances for a white Christmas are low. There may be some high cloud cover at times and cooler temperatures. But very cold weather is not expected.

 

If you are traveling west Tuesday-Thursday, the chance for snow returns mainly at the high passes and west-facing slopes. There isn’t a big storm coming in, but be prepared for some winter travel in the high country, especially the San Juan region of southwestern Colorado.

Heavy mountain snow; some clouds and light snow lower elevations this weekend

12:15 PM MST, Thursday, December 12, 2019

A fetch of Pacific moisture and some embedded storms will bring a period of snowy weather in the mountains through Sunday, especially Friday night and Saturday. Well over a foot is likely near the divide. Watch out for winter travel at the high passes. 3-6 inches is possible as far east as Nederland.

 

For the lower foothills and eastern plains, colder weather is likely Saturday and Sunday with some periods of clouds and some light accumulations of snow.  The chance for intermittent snow exists throughout the weekend but there should be long dry periods too. Right now it looks like there are two periods to watch for snow. 1) On Saturday we may see the development of some narrow east-west bands extending from the mountains onto the plains. Accumulations will probably range from little or nothing to about and inch or two where those bands occur. It looks like there may be a better chance for accumulation north of Denver. 2) After a possible lull late Saturday and/or early Sunday there may be a general areas of clouds and light snow in eastern Colorado on Sunday as the main storm center moves east to the south of Colorado. A few inches could come with that round, with the best chances south of I-70.

 

It’s looking dry next week, maybe quite mild by late in the week.

Some rain and snow today

6 AM, Thursday, December 5, 2019

A minor storm passing through the Front Range region today will keep it generally cloudy with intermittent precipitation. Precipitation is likely to be mainly snow above 6000 feet, with minor accumulations of 0.5-3 inches. Below 6000 feet we are likely to see rain or rain mixed with snow, changing to snow later in the day. Accumulations in the lower elevations should vary from nothing to about an inch.

Temperatures are likely to hover in the 30s most of the day. Therefore, the rain won’t do much to melt the existing snow and ice, but it may further saturate the snow on the ground which will freeze tonight. The good news is that daytime temperatures should climb well above freezing Friday and Saturday. The next cold front and chance for minor snowfall is late Sunday or Monday.