Dry & Windy Cold Front on Saturday

2:05 PM MDT, Friday, October 13, 2017

A cold front will sweep from west to east across the Front Range region on Saturday keeping temperatures in the 50s in the lower elevation. There is little moisture with it so there should only be a few clouds and probably no precipitation. Wind may be the most noticeable feature, especially in the higher mountains where it may feel quite chilly. Along the east slopes and high plains of the Front Range there may be a periods of cool gusty winds Saturday and Saturday evening.

 

After a frosty start on Sunday it should be milder and less windy, with above-average temperatures returning Monday and Tuesday.

 

 

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Season’s first snowfall across all elevations begins tonight

10:15 AM MDT, Sunday, October 8, 2017

A strong cold front this evening will be followed by snow (possibly beginning briefly as rain) through at least Monday morning. Accumulations are expected across all elevations.

 

Timing

Cold front: The main cold front should move north to south through the Front Range region this evening.

Precipitation: Snow higher elevations and rain lower elevations should begin in most areas before midnight.

Snow: Rain should change to snow in the lower elevations around midnight (a bit earlier north of metro Denver, later down in Colorado Springs). The best chance for heavy snow should be late tonight and Monday morning.

Clearing: Snow will taper off and end from north to south Monday afternoon and evening. Clear of partially clear skies are probable by Tuesday morning.

Accumulations

Mountains and foothills: generally 6-10 inches, some local areas around a foot

Near the foothills and Palmer Divide (Cheyenne, Fort Collins, Boulder, Broomfield, west & south sides of metro Denver, Castle Rock): 4-8 inches mainly by noon Monday

Other areas of the plains (east side of Fort Collins, Longmont, DIA, Colorado Springs): 2-4 inches.

 

Impact:

Tree damage/power outages: because the trees are still leafed out, there may be broken branches and damaged power lines in some places.

Roads: likely to becomes snow packed in the higher mountains and passes. In the lower elevations in may get snow packed and icy during intervals of heavier snow late tonight and Monday morning, but it should be mainly slushy or wet otherwise.

Freeze: Under clear (or partially clear) skies we should see temperatures in the 20s Tuesday morning across the Front Range urban corridor, and maybe a few local cold spots in the upper teens.

 

Wet snow Monday, all elevations

5:50 AM, Saturday, October 7, 2017

This is just a quick update from yesterday’s blog to say there is high confidence that the lower elevations of the Front Range (including the urban corridor) will see the first measurable snow Monday. The chances of more than 4 inches have increased too for the lower elevations, with more than 10 in some foothills localities. Given that the trees are still fully leafed out, you should prepare for the possibility of leaf damage and power outages, just in case. A hard freeze is likely on Tuesday morning,

First low elevation snow Monday?

5:45 AM, Friday, October 6, 2017

A weak disturbance and cool front moving through today may create a few cloudy intervals and an isolated shower or two. Then after a mild weekend a strong cold front on Sunday evening will bring cold weather and probably hard freezes and some snow early next week.

 

The air mass moving in Sunday night should be cold enough for snow at all elevations, but the questions are whether there will be substantial precipitation and whether that precipitation will last long enough to change to snow. Right now it appears likely that there will be at least measurable snow Monday or Monday evening along the Front Range and adjacent plains. But it appears less likely (but not yet ruled out) that there will be more than 4 inches in the lower elevations. Get ready for widespread frosts and freezes early next week too.

 

 

Cold front coming late Sunday

11:30 AM, Sunday, October 1, 2017

At 11:30 AM Sunday a cold front was moving south through central Wyoming and will likely move down the Front Range during the late afternoon and evening. Some areas of showers and thundershowers are already cooling things down in the mountains and may cool things off along the Front Range this afternoon  before the actual cold front gets here.

 

For tonight through Tuesday expect mainly cloudy and cool weather with intervals of rain or drizzle. Measurable snow may work it way down into the higher foothills including Nederland and Estes Park. Heavier snows (6-12″) are likely near and above treeline, especially in northern Colorado and southern Wyoming. In fact some snow might mix with the rain in in Cheyenne, but snow is very unlikely in the lower foothills and plains of the Colorado Front Range.

Finally warmer, but don’t get too used to it

10:20 AM, Saturday, September 30, 2017

After a week-long stretch of cool and occasionally wet weather, today is finally sunny and drier. Temperatures should reach to near the average for this time of year (low 70s in Denver-Boulder-Fort Collins). There is still likely to be a few showers or thundershowers around late in the day, so a few of us may get wet.

 

The weather pattern hasn’t changed all that much and we are likely in for another multi-day period of unseasonably cool and occasionally damp weather late Sunday through Wednesday. If we are lucky part or most of Sunday will be mild and dry. During the Monday-Tuesday time period daytime temperatures may struggle to reach the 50s in the lower elevations and there may be some periods of light rain or drizzle (light snow higher up), but it’s not looking quite as wet as last week.

 

Nighttime temperatures are not going to be as far below average as the daytime temperatures, but if skies clear by Wednesday morning there could be some frosts in some of the normally colder locations on the plains. That really wouldn’t be all that unusual for the this time of year. Today is the final day of the water year and I’ll be tallying the totals for Boulder and Denver tomorrow.

Warm Autumn equinox today, then cool autumn weekend

11 AM, Friday, September 22, 2017

Autumn begins at 2:02 PM MDT today and will be accompanied by warm weather. But the first autumn weekend will turn much cooler and may also be wet at times.

 

A cold front will sweep from north to south through the Front Range region late tonight and Saturday. In fact there may be an initial front Saturday morning and then a stronger push of cool air Saturday evening. Temperatures Saturday should hover in the 60s  in the lower elevations of the Front Range and possibly start falling later in the day. Sunday and Monday will probably get no warmer than the 50s in lower elevations.

 

Although it’s not a great setup for a soaking rain and mountain snow, it is the best chance we have had in a while for widespread measurable rain. Showery rain (and maybe a few thundershowers) are likely to affect some areas Saturday. By Saturday evening the chance for a multi-hour period of low clouds, drizzle, or rain increases. That possibility stays with us through early Monday, but I think there will also be some dry stretches and breaks in the overcast on Sunday. And yes, there will probably be some wet snow above treeline and maybe some flakes down into the upper foothills.