Monthly Archives: March 2017

Storm pullling away; mountain precipitation Sunday

6:20 AM, Friday, March 24, 2017

If you are just getting started this Friday morning, the worst of the storm for the Front Range is over. For many areas north of Denver the precipitation came to an end before the changeover to snow. There are some major impacts south and east of Denver. A stretch of I-25 is closed between Denver and Colorado Springs, and a portion of I-70 is closed well east of Denver, and wintry conditions will continue out east through the morning.

 

Active storm track

We are in a more active storm track for Colorado now. The next period with precipitation likely in Colorado/Wyoming is Sunday, but that will likely be very minor along the Front Range. Another chance comes in around Tuesday, and probably another storm toward the end of next week.

Highly variable impacts from tonight’s storm

6:00 AM, Thursday, March 23, 2017

Over just short distances the strong storm system tonight and Friday morning is likely to produce minor impacts in some areas (most likely the northwest Denver suburbs, Broomfield, Boulder, and Fort Collins) and major effects in other nearby locations (best chances for heavy snow and blowing snow in the Palmer Divide region and maybe across the south and southeast suburbs of Denver).  Colorado Springs will probably be south of the major impacts.

 

The storm appears to be evolving in a way that will produce strong northerly wind along the foothills beginning tonight, but not much easterly or northeasterly wind needed to concentrate precipitation development along the foothills. As you go south of Denver the north winds support upslope toward the Palmer divide and may aid in generating locally heavy precipitation there. Just east of Denver northeasterly winds nearer to the storm center may support a period of heavy precipitation and that may impact the eastern suburbs.

 

Most likely outcome:

Mountains: 6-12 inches of snow likely near and continental divide

Plains and lower foothills of northern Jefferson, Broomfield, western Adams, Boulder, and Larimer counties: rain showers this evening then snow toward Friday morning with accumulations ranging from 0 to 3 inches. Gusty north winds may develop.

Denver and DIA: rain showers this evening then snow and blowing snow toward morning with 1-4 inches

Plains and lower foothills of southern Jefferson, Douglas, and western Arapahoe counties: rain showers this evening then possibly some locally heavy snow and blowing snow by Friday morning with accumulations varying from 3-10 inches. Road closures may occur.

If you are traveling east on I-70 or on I-25 from Denver to Colorado Springs tomorrow expect winter driving conditions from wind and snow and possible closure.

 

What is the chance that the more intense precipitation will shift west?

It cannot be ruled out that an unexpected shift in the storm can bring heavier snow to Denver and Boulder, but that appears unlikely at this point.

 

 

 

Cooler Tuesday, Potential Storm Thursday Night

11:15 AM, Monday, March 20, 2017

The equinox ushered in Spring at 4:29 AM MDT today, but temperatures of the last two days are more consistent with the average for June 1st. On Saturday and Sunday Boulder set record highs of 80 and 78. Denver was even warmer with 81 and 80, but both fell 1 degree short of the record. Today the record in both locations is 80 which is within reach, but it is likely that we will fall just a little short of those records.

Cooler Tuesday

A cold front is slowly oozing down the northern plains today and should move through the Front Range early Tuesday. This is the type of front that will be felt more in eastern Colorado than in western Colorado. There is a small chance it will be strong enough to trigger some low stratus clouds and localized drizzle in eastern Colorado. But it is more likely that it will just cool us down a bit but remain dry across most of the area.

 

Storm late Thursday and early Friday?

There has been good consistency for days regarding a significant storm moving through Colorado Thursday and intensifying as it moves to the east of the Front Range by Friday. Most indications are that it may only have minor impacts along the immediate Front Range foothills and adjacent plains. But recent guidance suggests the chance that the storm may slow down and track a little farther south which would put the Front Range region in a more favorable location for significant rain and wet snow Thursday night and/or Friday morning. More updates will come in the next few days.

Record warm; changes later next week

11:50 AM, Friday, March 17, 2017

Warmth

The unusually warm weather will continue into early next week, with Saturday and Sunday likely to be the warmest days. Boulder tied a record high of 78 this past Wednesday, but Denver didn’t quite reach theirs. For Saturday and Sunday the records in Denver are 82 and 81, both set in 1907. In Boulder the records for Saturday and Sunday are both 77 (set in 2004 on the 18th and 1907 on the 19th).

 

Denver should get close to the record each day with a small chance of setting a new record. If it reaches 82 that would be the earliest that temperature has been recorded. The earliest 80-degree in Denver was set this year on February 10th, a remarkably early occurrence.

 

Boulder has a better chance of setting a new record on at least one day this weekend. The earliest 80-degree day in Boulder is 80 on March 16, 2015.

 

March snowfall

March is on average the snowiest month in Boulder and Denver (and most locations along the Front Range urban corridor). So far there has been no measurable snow in either location this month. The unusual warmth of February and the first half of March have coaxed some trees and shrubs out of dormancy making them more prone to damage from freezes or wet snow that are likely yet to occur.

 

Medium and long range forecasts suggest a more active storm track across the Rockies may develop later next week. Although there is more uncertainty in longer-range prediction, there has been agreement between models on this potential change. So I wouldn’t bet on a snowless March yet.

Wind, cooler Monday

11:55 AM, Sunday, March 5, 2017

A Pacific cold front will bring wind and snow to the mountains tonight and Monday, and mainly just wind and cooler temperatures to the eastern foothills and plains. Accumulating snow may extend east of the continental divide enough to impact Nederland. Some flurries or snow showers may even make it to the urban corridor.

 

But the main impact for the lower foothills and plains on Monday will be temperatures 15-20 degrees cooler with a strong wind possible. There may even be some gusts over 60 mph in some areas.

 

By Wednesday mild spring weather is likely to be back in force.