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).
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.
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.
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.
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:
- 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.
- 4-8″ central Denver, and Denver’s south suburbs.
- 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.
- <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.
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)
12:45 PM MST, Friday, March 8, 2019
A Pacific cold front will blow through this evening (probably between 4 and 8 PM for the Front Range region) accompanied by some brief showers of rain, snow, and or graupel. Precipitation probably won’t fall in all areas, but some local spots may get briefly moderate precipitation with strong west or northwest wind. The Storm Prediction Center has the area outlined for possible thunderstorms. There are a few lightning strikes showing up in western Colorado now, but it isn’t a lot, so I think there is a chance for thunder, but it is small.
After the precipitation is over the risk of gusty west or northwest winds may continue into early Saturday, with some localized gusts around 60 mph. The chances for precipitation for the remainder of the weekend are very low, and temperatures are likely to be near or a little below average.
For the mountains and high passes, more heavy snow today will likely taper to localized areas of lighter snowfall on Saturday. The avalanche risk might continue into the weekend, so check local travel routes and advisories if you are heading west.
7:30 AM MST, March 2, 2019
For those who followed this blog the last two days, there are two adjustments to the forecast snow.
- The potential for some heavy snowfall rates has shifted south a little. This means the south part of Denver and Colorado Springs are a little more at risk, while Fort Collins and Cheyenne are a bit less at risk for the higher amounts. The risk for Boulder and the north part of metro Denver has not changed.
- It had looked like the storm would be over on Sunday morning, but now it appears that additional light accumulation may occur into Sunday night.
As of 7am, 2-5 inches has fallen in Fort Collins and Cheyenne, less to the south. An east was band of snow is current affecting the northern part of metro Denver.
There may be a lull during the late morning or midday hours, but we still expect the main snowfall this afternoon and overnight. After a possible lull in action Sunday, some more light snow and flurries are likely to develop (mainly from Boulder-Denver southward) late Sunday and Sunday night.
Additional Accumulations (7AM Saturday to 7AM Sunday)
5-9″- in and along the foothills from Boulder County southward (Denver west of I-25, Nederland, Boulder, Broomfield, Castle Rock, Colorado Springs)
3-6″- east side of Denver, Longmont, Fort Collins
2-4″- Cheyenne, Greeley
Additional accumulations late Sunday
dusting – 2″ mostly likely from Boulder-Denver southward