Monthly Archives: March 2019

Snow tonight

11:45 AM MDT, Friday, March 29, 2019

The trend has been in the direction of a widespread snowfall across the Front Range region and adjacent plains tonight. Although a major storm isn’t expected, winter travel condition are likely in some areas after dark and into the late night.

There will probably be some rain around into the late afternoon, mixing or changing to snow in some of the heavier showers. The best chance for steady snow will probably develop between 7-10 pm this evening and then taper off from north to south before sunrise. The snow may come down hard for a brief period after dark, especially in and near the foothills. Some light snow may linger into early Saturday, especially for the south and east sides of metro Denver.

 

Most likely accumulations through early Saturday:

Above 7000 feet: 3-8 inches

Cheyenne, Boulder, Broomfield, west side of Denver, Castle Rock: 2-4 inches

Fort Collins, Longmont, DIA, east side of Denver, Colorado Springs, 0.5-2 inches

 

Saturday afternoon and Sunday

Mainly dry, but cool. Cold air aloft on Sunday will probably cause a few showers (rain or snow) to develop in the late afternoon and evening. These will probably be most numerous in the central and southern mountains of Colorado. Milder weather sets in on Monday.

Colder, damper weather this weekend

12:35 PM MDT, Thursday, March 28, 2019

At noon a cold front was sweeping southwest across the northeastern Colorado plains. As a result the temperatures along the Front Range may start to level or cool off a little as we go through the afternoon.

 

The colder air mass and an upper level storm with Pacific moisture are likely to result in a colder, occasionally damp weather Friday and Saturday. There could be some sprinkles around this evening, and a chance of showers (rain plains, snow mountains) Friday afternoon. But the best chance for precipitation is Friday evening through early Saturday and that would be mainly snow at all elevations. The most likely accumulations are 2-6 inches above 7000 feet, and a trace to 2 inches below 7000 feet. There are some mesoscale models suggesting a little more than that in the lower elevations, but that chance appears small and I’ll update tomorrow if necessary.

 

Sunday should be the better of the weekend days, but still a little cool. Mild spring weather is likely to be back on Monday.

Precip this evening, then mainly dry this weekend

Noon MDT, Friday, March 22, 2019

A fast moving disturbance is likely to spin up as it moves through eastern Colorado and into Kansas this evening. Showery precipitation, maybe a thundershower, will probably move into the area this evening. Precipitation will be mainly snow in the mountains (1-3 inches in Nederland and Estes), and mainly rain in the lower elevations (below 7000 feet). Where the precipitation lasts a little longer in the lower elevations the chance for it to change to snow is greater. There is about a 50-50 chance for some light accumulation of wet snow in the southeastern suburbs of Denver and at DIA where the precip will probably last longer than on the west side. For most of Denver-Boulder and Fort Collins, the chance for any measurable snow is less than 20%.

 

The weekend should be mainly dry with near seasonable temperatures. Then by Tuesday and Wednesday we are likely to get a few days of afternoon temperatures at least 10 degree above average (mid to upper 60s in Denver-Boulder).

Vernal Equinox; will Spring really get here?

11:50 AM MDT, Thursday, March 20, 2019

Spring arrives at 3:58 PM MDT today and the weather will be right about what climatology suggests. The average this time of year for Denver-Boulder is for a high in the mid 50s and a low in the upper 20s, and we may stay close to that through the weekend. A weak disturbance will probably bring some brief showers to some parts of the Front Range region Friday or Friday night (rain in the lower elevations and snow or mixed above 7000 feet).

 

Is Spring slow this year?

For those of you wondering if the crocus & daffodils seems a bit slow this year, they are. March has been much colder than average so far, and that followed a colder than average February (December and January were a bit warmer than average).

The real notable feature this winter hasn’t been remarkable cold waves, but rather, the absence of warm spells. There was one cold snap that sent us into record low territory on March 2-3rd, and a couple of notable (but not record) brief cold snaps around New Years Day and on February 6-8th. But what we haven’t seen is warm waves that feature a stretch of days reaching 60 or more. For the period since the current Boulder climate station was established in 1990, the average number of days reaching or exceeding 60 during Dec-Jan-Feb is twelve. This season (Dec-Jan-Feb) there were only 4. Only three winter seasons had fewer 60-degree days in Dec-Jan-Feb: 2000-2001 had 3, 1992-1993 had 2, and 2009-2010 has 1. The month of March reaches at least 60 an average of 13-14 times, and this year we have not reached 60 yet. There is a tiny chance of reaching 60 today or tomorrow and a better chance for a couple of 60-degree days  in the middle of next week, but this month won’t get near the average.

Snowstorm peaks over the next 3-8 hours

11:30 AM MDT, Wednesday, March 13, 2019

The heavy rain this morning has changed to snow across the area as we enter the peak hours of this storm. Although there are north-northwest winds at the surface, some easterly component aloft is managing to push the heavy precipitation into the foothills. Expect periods of heavy snow & wind area-wide until early afternoon, and then the heaviest snow will probably shift east a bit (roughly along and east of I-25) during the afternoon.  Snow totals will likely be 3-7 inches west of I-25 and 6-12 in the eastern part of Denver metro where winds will also cause lots of blowing snow. Snow should end tonight.

A variety of winter conditions expected for the Front Range region Wednesday

1:00 PM MDT, Tuesday, March 12, 2019

A very strong cyclonic storm will move through eastern Colorado and into Kansas Wednesday and Wednesday evening. Rain and then snow & blowing snow are likely with a range of possible accumulations. Even within the Denver metro accumulations below 6500 feet might vary from less than 3 inches in some northwestern suburbs to a foot with considerable drifting on the east side. Very strong north winds will cause some blowing snow, especially along and east of I-25.

Timing:

Scattered rain and maybe a thundershower are possible this evening or overnight. Rain will change to snow early morning Wednesday around Cheyenne and the Front Range foothills above 6500 feet. Rain should change to snow in other areas below 6500 feet during the late morning and early afternoon. Changeover is likely first where the heavier rain is. The snow should taper off before Thursday morning along the Front Range.

 

Accumulation below 6500 feet:

  1. 6-12″ with blowing snow: Heaviest accumulation and blizzard conditions are most likely around Aurora and DIA extending northeast onto the plains (especially between I-76 and I-70). Other areas with the good potential for heavy snow and blowing snow are the north facing slopes of the Palmer Divide and Cheyenne Ridge (this includes Cheyenne, and the area south of Denver but north of Colorado Springs). Expect travel disruptions along I-76 and I-70 east of Denver, parts of I-25, and at DIA.
  2. 4-8″ central Denver, and Denver’s south suburbs.
  3. 1-5″ closer to the foothills. This type of storm often has a relative minimum (due to lack of upslope flow) in a corridor in and along the lower foothills from Fort Collins to Golden, including Boulder, Broomfield, and Longmont. There is always a chance that the storm can surprise us with a wobble that shifts the heavy snow farther west into Boulder, but I’d say that is only about a 20% chance.
  4. <3″ in Colorado Springs, but watch out for strong north winds

Accumulation above 6500 feet:

4-14 inches: here the variability is mainly elevation dependent (probably 5-8 around Nederland and Estes)

What is a blizzard?

This is a good time to remind everyone that a blizzard is not just a big snowstorm. We can have blizzards with relatively small accumulations. A blizzard is when the combination of snow and wind cause dangerous blowing snow conditions that could be life threatening if caught out in the open. Blizzard warnings are issued when visibility in snow and blowing snow is expected to drop below 1/4 mile for several hours.

Strong spring cyclone in eastern Colorado on Wednesday

1:30 PM MDT, Monday, March 11, 2019

A spring storm will develop and strengthen rapidly Wednesday and Wednesday evening as it moves from eastern Colorado into western Kansas. Scattered rain and even some thunderstorms may occur Tuesday night into Wednesday, and then snow and blowing snow, especially on the northeastern plains of Colorado, late Wednesday and Wednesday night. This is the kind of storm that could close I-70 and I-76 east of Denver, and possibly sections of I-25.

 

The specific location of the storm as it intensifies is very important for potential snow in the Denver-Cheyenne corridor. Well to the north of the storm center northeasterly “upslope” winds support heavier snow once the changeover to snow occurs, and this may occur from Fort Collins to Cheyenne. Closer to Denver-Boulder the winds around the storm may be north or even northwest along the foothills reducing the potential in places like Lyons, Longmont, Boulder, and Golden. To the east this is less of an issue, so DIA and Weld County could have a worse storm than areas nearer the foothills. This can all change with slight shift in the track.

 

For now the following looks most probable:

Possible blizzard conditions and more the 6″ along and east of I-25. Probably 12″ is spots out on the high plains east and northeast of Denver. Prepare for significant disruption at DIA.

 

Probably less than 6 inches west of I-25 from around Loveland south to Golden (including Boulder). Also lesser amounts in Colorado Springs.

 

4-8″ Fort Collins, Cheyenne, and the north-facing slopes of the Palmer Divide (south suburbs of Denver)