Mild & Windy Saturday, Cold & Snowy Sunday

3 PM MST, Friday, November 9, 2018

After a mild a windy Saturday, a strong cold front will move north to south through the Front Range region late Saturday afternoon and evening. Expect a cloudy and cold day Sunday with temperatures staying below freezing all day. Light accumulations of snow are likely, especially late Saturday night and Sunday morning.

 

Likely Accumulation:

3-5″ – Nederland, Eisenhower Tunnel, Estes Park, Palmer Divide region

1-3 inches – Denver-Boulder Metro, highest on west side.

Dusting – 2 inches – Cheyenne, Fort Collins, Weld County, Colorado Springs

 

 

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Mountain snow this weekend, dry Front Range foothills and plains

3:30 PM MDT, Friday, November 2, 2018

A couple rounds of snow are likely this weekend in the high elevations near and west of the continental divide, with dry and seasonably mild weather for the Front Range foothills and plains. Saturday will likely be a little cooler than Sunday, but neither day will be cold compared to the seasonal average.

Mountain snow

Snow is expected to cause some winter driving conditions at and near the high passes tonight. Then after a relative lull late Saturday into early Sunday there will probably be more high elevation snow develop on Sunday afternoon into Monday. The accumulations will be mainly near and west of the high peaks, but some accumulation will probably occur within a few miles to the east side of the continental divide. I expect very little in Nederland and Estes Park.

 

Next chance for the plains

After tonight the next fast moving Pacific storm system may bring some sprinkles or flurries to the lower elevations Monday. But the next real chance for snow in the lower foothills and plains appears to be Wednesday or Wednesday night. That will be updated as we get closer.

Snowy mountains; rain then some snow lower foothills and plains

6:00 AM MDT, Tuesday, October 30, 2018

 

Intermittent precipitation during the day should be mainly snow above 7000 feet and mainly rain below 6000 feet, with rain changing to snow between 6000 and 7000 feet. During the late afternoon and evening northeasterly flow through a deep layer of the lower atmosphere will probably result in a period of steady precipitation changing over to snow at all elevations. Snow should end from Denver north late tonight, but may linger into morning for the Palmer Divide region and south.

 

Forecast accumulation

Big variation can be expected from mountains to plains with this storm. Even on the plains you may not have to go very for to the east in northeastern Colorado to get little or no snow.

Above 7000 feet: 5-10 inches (locally 12″ in some areas south of I-70)

6000-7000 feet: 3-6 inches

Boulder, Broomfield, Denver (south & west suburbs), Colorado Springs: 2-4 inches

Fort Collins, Longmont, east Denver & DIA: 0-2 inches

 

Does it really almost always snow on Halloween?

Snow on Halloween is a reputation around here. The Boulder climate record shows that the phrase “almost always” is a bit of an exaggeration, but it’s easy to see where the snowy reputation comes from. In the last 30 years there has been measurable snow (at least 0.1 inch) five times on Halloween. But if we look at the week centered on Halloween (Oct 28-Nov 3) there has been measurable snow 16 out of the last 30 years, or 53% of the time. By comparison the 1-week periods that include Thanksgiving, Christmas, Presidents Day, and St Patrick’s Day all have about a 60% chance for measurable snow. So Halloween week does signal the ramp-up to winter season snow probability.

 

Will Halloween be white?

4:00 PMĀ  MDT, Monday, October 29, 2018

I’ll give a real update early tomorrow morning. This is a quick note to say that my snow forecast this morning might be a little too timid. If the current trend continues people in and along the Colorado foothills should be ready for some sloppy conditions tomorrow in the higher terrain, and late Tuesday into the overnight in the lower elevations near the foothills.

 

 

Autumn returns Tuesday

5:50 AM MDT, Monday, October 29, 2018

After another unseasonably warm day on Monday, cooler weather will return to Colorado and southeastern Wyoming Tuesday and Wednesday. There is even a good chance for a minor snowfall from the south Denver suburbs and southward late Tuesday, and a smaller chance north of Denver.

 

The cold front should slide through the area by Tuesday morning making it about 30 degrees colder than Monday. Intermittent precipitation on Tuesday will likely be rain in low elevation areas at first and snow later in the day. But snow accumulations from Denver north will likely be minor, if any. The best chance of accumulation is in the foothills and mountains. South of Denver, including the south suburbs, the chance for 1-4 inches is greater. Local areas of over six inches will probably be observed in the Palmer Divide region and mountain/foothills areas south of Denver.

 

Halloween evening is likely to by chilly, but drier.

Cold and snow returns this evening

9:15 AM MDT, Saturday, October 13, 2018

A cold front is just now (at 9 AM) pushing southward into northeastern Wyoming and will likely reach Cheyenne later in the afternoon and move south through the Front Range and high plains of Colorado this evening. Clouds and precipitation are expected to develop within a few hours of the front. There may be a small amount of rain at first, and then periods of snow this evening into Sunday. The snow will probably become showery and light during the day Sunday.

 

Snow accumulation

*the high end of the ranges given below are likely in a subset of the region where narrow southwest-to-northeast bands of heavier snow develop

High plains and Fort Collins, Longmont, Denver/DIA, Colorado Springs: 1-4″

Palmer Divide, foothills, south and west Denver suburbs, Broomfield, Boulder: 3-6″

Cheyenne, Nederland, Rocky Mountain Park: 4-7″

 

Record Cold

Low elevation temperatures will plunge quickly to the 20s after the cold front, stay in the 20s on Sunday, and fall to the teens by Monday morning with some of the normally colder spots along the Front Range getting into the single digits. Record lows on Monday morning are likely throughout the Front Range urban corridor. The current records that are likely to be broken on Monday morning are:

Denver 20

Boulder 20

Fort Collins 19

Cheyenne 17

 

Trees and vegetation

There could be some tree limb damage tonight. The snowfall is not expected to be very deep or exceptionally dense, so widespread severe tree damage is not expected. Still, I’d advise not to park under trees and have your electronics charged up just in case.

 

Equally damaging to trees and shrubs could be the extreme early-season cold. That damage might not be obvious until much later.

 

Roads

Although there is still a reservoir of warmth in the ground, the cold temperatures and the fact that the heaviest snow may come during the night means that you should expect icy and snow-covered roads tonight and early Sunday. Road conditions should improve Sunday.

Brief warm-up, then cold & snow returns Saturday evening

6:30 AM MDT, Friday, October 12, 2018

Enjoy the sunny and warmer weather today through at least Saturday morning. The next cold snap beginning late Saturday will be colder than the previous one, but it won’t be as prolonged. A widespread light-moderate snowfall is likely Saturday night into Sunday.

 

Timing

The strong polar front will probably move south through eastern Wyoming Saturday morning (Cheyenne in the midday hours ), and southward through eastern Colorado from mid afternoon to early evening (probably late afternoon in Denver-Boulder). Clouds and periods of precipitation are likely to begin a few hours after the front and continue through Sunday morning. There may be some rain at first, but this one should be mainly snow.

 

Snow Accumulation

1-3″ high plains including east side of Denver, and around Colorado Springs

2-5″ inches in and near the lower foothills, including west side of Denver, Boulder, and around Cheyenne

4-7″ inches higher elevations, including Nederland

 

Record Cold?

Temperatures should plunge quickly to the 20s Saturday evening, stay near or below freezing Sunday, and really fall under clearing skies by Monday morning. The record low Monday morning for both Denver and Boulder is 20 (both set in 1970). It looks likely that those will be broken with temperatures in the teens.

 

Warmer pattern coming

It looks like we will see a pattern shift to drier and warmer autumn weather next week after a very cold start on Monday.