Winter in Colorado, 2012-2013 (Pueblo, Grand Junction: camp, stats, castle)

[JukieF]

Brrrrr!!!!!

I moved to New Hampshire three and a half years ago, so snow doesn't bother me. The second winter we were there it started snowing at the end of November and then snowed at least once a week (sometimes twice a week) from then until into March. By the end of winter, we had about five feet of snow piled up in our yard. It just piled up, one storm after another, and never melted until spring.

But it has never gotten as cold in NH, other than for a few days here and there, as it's been in Colorado for the past several weeks. I came back out here in March to take care of my parents, and I can never remember having lows like this for such a long time, especially in Pueblo, of all places. I hadn't lived in Pueblo since 1985 (but spent 17 years in Fort Collins). I was expecting it to be fairly warm in Pueblo, especially compared to the rest of the state--and to New Hampshire. Instead, it's been absolutely brutal. Lows in the single digits and teens day after day after day.

Someone please tell me. Is this unusual? Or have I just forgotten how cold Colorado can be?

Makes me almost want to go back to balmy New England. :-)

[CosmicWizard]

Delta.....The temps have been colder down low in the valleys than they've been in the high country.

Jukie...the cold is not in the least unusual. It's been cold like this 6 out of the 7 winters I've been in Grand Junction. The warm winter a year ago was an abberation compared to the other 6.

[jazzlover]

The Front Range and the Western Slope of Colorado have two very different cold regimes. The Front Range gets its coldest weather when a strong push of Arctic air slides down the Eastern Slope from Canada. Those temperatures can be quite cold, but usually don't last for more than a few days. Why? The prevailing wind is generally from the west. When a high pressure system sets up in the west, it will create strong Chinook winds on the Eastern Slope. Those winds compress and warm the air as it descends the Eastern Slope, and they can give winter temperatures on the Front Range up to the low 60's, albeit with a lot of wind.

That same high pressure regime will cause the cold air to stagnate in the western valleys that, depending on the length and strength of the high-pressure system can "embed" cold, smoggy stagnant air in the western valleys for days or weeks at a time in winter. If the valleys get snowcover, that will intensify the cold air inversion and the cold air can become more entrenched and that snow may stay on the ground all winter.

An example of how those high pressure systems influence the Western Slope and Front Range differently can be illustrated by the frequent example of Denver reaching the 60's on January day, while Gunnison, 200 miles southwest of Denver on the Western Slope may not reach 0° F. for a high on the same day--60 degrees different at the same time.

[jim9251]

And we get that inversion layer on the western slope too. Ridgway isn't an official NWS reporting station but it's one of the coldest places in Colorado during winter.

[jazzlover]

One other note: Both the San Luis Valley in southern Colorado and North Park in northern Colorado are on the east side of the Continental Divide, but their winter cold regime is more akin to the Western Slope than that of the Front Range. Both North Park and the San Luis Valley are prone to the same air stagnation and inversions that can plague the western valleys--Gunnison, Uncompahgre, Grand (Colorado River), and Yampa valleys.

[CarsonCityKid]

A question about inversions... At what elevation do they tend to not occur? Every mountain town on the Western Slope lies in some sort of valley... So do inversions happen in every town sometimes? Ridgway at 7000ft? Silverton at 9300ft? do they ever occur here or are they just less likely to occur here?
Thanks.

[jazzlover]

Originally Posted by CarsonCityKid

A question about inversions... At what elevation do they tend to not occur? Every mountain town on the Western Slope lies in some sort of valley... So do inversions happen in every town sometimes? Ridgway at 7000ft? Silverton at 9300ft? do they ever occur here or are they just less likely to occur here?
Thanks.

Yes, they can pretty much occur at any elevation where the air can stagnate in a valley. Of course, they may be less obvious where there are not pollution sources whose emissions will be trapped by the inversion. As an example, today's Crested Butte usually has pretty clear air in the winter, even though the place can get inversions. But, look at historical photos of Crested Butte in the days when a lot of coke ovens were running and the photos would often show a nearly black pall of smog trapped by the inversion hanging all across the town.

Some of the worst places that I've seen for winter inversions containing tons of pollutants are the Salt Lake Valley and the Cache Valley in Utah. In both places, like some western Colorado valleys, inversions can last for weeks under the right conditions. In Salt Lake City, the winter inversion layer generally runs up to about 5,000 feet elevation--reliable enough that there actually is a significant difference in real estate prices for homes above or below that elevation around SLC.

[Idunn]

I can vouch for air quality in Salt Lake City, UT being dreadful sometimes. In driving west on I-80 it was blue sky until past Park City, and lovely there. But shortly after, in beginning to drop down the canyon towards SLC, it soon began to become strangely overcast. And by SLC the "air" was more a dark and noisome pea soup in complexion, and that early afternoon more like dusk. Nor my imagination, as large digital highways signs along the interstate advised all to remain indoors who could, for health reasons.

This was in December, and although the worst of it seemed to be centered over SLC, this pall stretched unbroken west as far as Wendover, UT, on the Nevada state line. Left at last only in climbing in elevation once past West Wendover. One could then look back east over the top of what appeared a vast, dark fog bank.

[Idunn]

Beyond week 2, the CPC monthly and seasonal outlooks both maintain enhanced odds of below median precipitation for the Southwest. Based on these factors, drought persistence or intensification is expected for most of the Southwest. [1]


This unfortunately is the likely outcome for the winter of 2012/2013 in Colorado: continuing and worsening drought.

Colorado is not mentioned by name, although apparently considered part of the Southwest by the NWS, so the forecast quoted applicable. States in the northern Rockies, Wyoming, Idaho and Montana, are mentioned elsewhere; Wyoming largely with the same drought conditions as Colorado; only northern Idaho and Montana with improving or no drought conditions. This forecast is through March 31, so basically the winter and best last chance for any appreciable snow.

From the provided link one can access a map of the current and forecasted drought by choosing "Drought" (upper left hand corner of page).

1) 'Discussion for the Seasonal Drought Outlook,' National Weather Service
Climate Prediction Center - Expert Assessments: United States Seasonal Drought Outlook Discussion

[jazzlover]

^ If the CPC prediction is correct, this winter may be a carbon copy of last winter--some snow in December and January, and little thereafter. The rub is that Colorado went into the summer season in 2012 with reservoir levels near normal. This winter, just about all of the state reservoirs are very low--with some completely dry. Even a normal winter snow season would not refill many of them; a dry winter will mean disastrously low water levels and streamflows next summer, not to mention potential wildfire danger that will make 2012's fires look mild. As I've posted before, the only people not extremely concerned about Colorado's water situation for 2013 are the people too ignorant to understand the peril. The people whose job it is to be concerned about the state's water supplies ARE extremely concerned.