Blog Archives

World Record Fattest Hummingbird

Despite our late snows and cold weather…


[Aside: For the record, April 2013, was Denver’s fifth coldest April since observations began in 1873. The average temperature was 5.7°F (3.2°C) below normal. 20.4 inches (52 cm) of snow fell during the month making it the eleventh snowiest April on record. Boulder, a city about 30 mi (48 km) to the northwest of Denver and closer to the foothills of the Rockies, had its snowiest April ever with more than 4 ft (122 cm) of snow measured during the month.]

…and, with the last, late-season snowstorm coming on May 1, the hummingbirds still managed to return to the mountains about on schedule this year, arriving during the last week of April. They were hungry after their long migratory flight, so the hummingbird feeder was deployed outside as soon as the first trill of hummingbird wings was heard near the house. Surprisingly, especially for so early in the season, I noticed the level in the feeder dropped very quickly in the first few days after I put it outside. I surmised that we had very hungry birds this year or, maybe, there were many more hummingbirds in the area using our feeder than I had seen.

Then, last weekend, the real explanation for the rapid consumption of hummingbird nectar appeared at the feeder:


That’s a Bullock’s Oriole, and I’m no ornithologist (IANAO 🙂 ), but it, apparently, likes sweetened water and it has a beak small enough to fit into a hummingbird feeder. It had a “field day” taking long gulps out of the feeder, despite the cackling and diving of the hummingbirds as they tried to scare it away from their food source. Needless to say, until the wildflowers start blooming, there will probably be an ongoing confrontation between the oriole (or orioles) and the hummingbirds.


A Snow Shower in May

Often in May, with the air still retaining some winter chill, and the land warming rapidly from near-summer sunshine, convective showers of snow and hail form over the Rockies and adorn the sky-scape.  This happened over the weekend and I caught this image showing a beautifully picturesque shower as it was passing by to the east.  The fibrous texture of the cloud’s top results from ice crystals formed as the shower cell bubbles skyward due to the heating below.  Grayish snow and soft-hail can be seen falling out of the cloud obscuring the land surface underneath it.  Surface temperatures were in the low 50s°F (12°C) in the sunshine, dropping to about 40°F (4°C) when one of these showers passed overhead.  The snow and soft hail would whiten the ground, briefly providing a wintertime look to the May landscape and angering the nesting robins chilled by the sudden squall.

A Springtime Snow Shower over the Rockies

A Springtime Snow Shower over the Rockies

May Snow Scene

With the early May sun providing about 5 times the energy as the mid-winter sun (in the Northern Hemisphere at 40ºN latitude assuming a clear sky), it doesn’t take long to melt the 6-15 inches (15-38 cm) of snow that fell along the Colorado Front Range yesterday. Before it all melted, I took this beautifully white picture looking west from the southern Denver suburbs towards the mountains. The higher peaks along the Continental Divide which would typically be visible behind the mountains shown are obscured by the cumulus clouds in the picture.
Picture of Colorado front Range mountains after a snowfall

May it snow?

Central Colorado had a very snowy April—for instance, Boulder, CO set a record for April snowfall measuring more than four feet (122 cm) of snow during the month…and most of that fell during a two-week span in the middle of the month. May has continued the pattern with an all-day snowfall today along the Front Range of the central Rockies. What does a mid-spring snow day look like? Much like a mid-winter snow day except for the perturbed robin and the confused buds…

A collage of 4 pictures showing snowy scenes from May Day 2013, in central Colorado

Snowy scenes from May Day 2013

The I-70 Snowstorm

This has been a snowy March along the Front Range of Colorado and the most recent storm which blew in Friday night and lasted through much of yesterday (Saturday) was unusual in a number of ways.  First, it was quite a cold storm for late March.  For instance, yesterday’s clouds, snow, and strong north winds held Denver’s high temperature to only 23°F (-10°C), a whopping 34°F (19°C) below normal.  The storm also broke several records for single-day snowfall for March 23, almost 11 inches (28 cm) in Boulder, more than a foot and a half (46 cm) east of Denver over the wheat fields that spread to Kansas.

One other weirdly interesting aspect of this storm is that it is following a track just about due eastward from the snow field it left in Colorado yesterday to the areas it will affect tomorrow as it moves off the east coast of the U.S. in the afternoon.  In fact, it seems to be using I-70, one of the essential east-west routes of the Interstate Highway system, as its guide.  Just look at this map of I-70’s route overlaid with the area of snow already deposited by the storm and forecasted to fall in the next 24 hours:


There’s not a bad correlation at all between the path of I-70 and the path of the storm’s snowfall.

It is not uncommon for a storm to move more-or-less due eastward across the U.S., following the winds in the upper atmosphere which usually blow from west to east at mid-latitudes. However, it is unusual in late March for a storm to take this track and and leave such a continuous layer of snow this far south across the central U.S.  The biggest downside from the storm is probably the chaos it has had and will have on I-70 traffic, the biggest upside: the farmers in the grain belt will be happy.  Now, I’m looking forward to spring!

Snowless Winter? Not entirely snowless, but certainly snowstarved

There have been many headlines about the lack of snow over the conterminous U.S. this winter particularly because the northeastern U.S., a major source region for headlines, has experienced an unusually mild winter.  For instance:

Outdoor Enthusiasts Adapting to Snowless Winter West of Boston
Festival has Near Meltdown
Towns Save Money in Snowless Winter
Home Depot Given Warm Winter Boost

The less than normal snow extent also affects many parts of the western U.S. including where I live in Colorado.  It was visually evident during the President’s Day weekend when I noticed I could see most of my two-foot tall snow stake at our house at the 8300-ft level in the Colorado mountains:

Snow on the ground, Feb. 2012

That contrasted with the conditions of a year ago which were much different.  Just how different?  This picture from last year’s President’s Day weekend shows the same snow stake at the same location:

Snow on the ground, Feb. 2011

Ah yes!  What a difference a year makes.  Even more striking is the difference in the amount of water contained in the central Colorado snowpack this year as opposed to last.SWE in central Colorado, 21 February 2012  The graph to the right shows the snow water equivalent (SWE), the amount of water in the snowpack measured in inches, for a location not too far from the snow stake comparing Jan 1-Feb 21 of last year with the same period this year (last year=blue, this year=red).  Again, what a difference a year makes!  Last year the snowpack contained more than 3″ of water (if you were to melt all the snow in a column); this year the pack has about ¾”, just 25% of last year’s amount.

The dearth of snow in the Central Rockies is not confined to the area just around my snow stake.Colorado snowpack, 21 February 2012  This next map, from the Natural Resources Conservation Service (NRCS—a part of the U.S. Dept. of Agriculture), shows all of Colorado having a below average snow season this year. The NRCS collects data about the snowpack (snow depth, water content, etc.), both remotely and in-situ, and produces a variety of maps depicting the condition of the wintertime snow cover. Their Colorado map set can be accessed from here.

Snowpack over the western U.S., 21 February 2012
To the right is an even bigger picture view, again from the Natural Resources Conservation Service.  Most of the western U.S. except the far northern regions and a few spots in the southern Rockies have had a snowstarved winter.  If you are interested in monitoring changes in the snowpack across the western U.S., here’s where you can access daily updates to this map.

Much of this winter’s snowlessness across the U.S. is related to the location of the jet stream.250 mb average jet stream winds 24Nov11 to 21Feb12  Winter storms generally follow the path of the jet stream (Storms develop along thermal boundaries between cold air to the north and warm air to the south, in the Northern Hemisphere.  The jet stream is created by these same thermal differences.) Generally, cold air and snow will be more prevalent along and on the poleward side of the jet stream’s location.  This winter, on average, the jet stream has been farther north than normal especially over the western U.S. as this map shows (magenta arrows show average position of the jet stream).  Usually, those magenta arrows would be hundreds of miles farther south and the northward bulge over western North America would not be as pronounced.  This is a pattern which is often seen during La Niña conditions (cold water over the central Pacific Ocean) like what we have this winter—although this year the jet stream is even farther north than in typical La Niña years.

And, as with all things weather, by the time I post this missive it will be old news.  In the past few days the jet stream has shifted south and west (as shown by this satellite picture and wind speed map from today).
Jet Stream Over the U.S. 22 Feb. 2012It now enters the U.S. over the Pacific Northwest and dives down into the central Rockies.  Meanwhile over the eastern U.S., it’s farther south as well (and, not surprisingly, Richmond, VA had a few inches of snow this past weekend). For Colorado, this has meant a return to snowy conditions for our mountains with fresh powder at the ski resorts being measured in feet rather than inches.  This is good news for the western watersheds (but bad news for my snow stake).  And for the next 10 days, at least, it looks like the jet stream will remain closer to its normal position across the western U.S. leading to more normal wintertime weather.

Snowy Springtime Timelapse

During this transitional season from winter to summer, as the sun travels higher in the sky each day and hints of summer’s warmth become more frequent, the weather responds to the nature of the season as well.  Often, here in the central Rockies of Colorado, there are days when still-chilly northwesterly winds are accompanied by frequent snow showers in the unstable atmosphere of spring—unstable because the atmosphere retains its cold memory from winter, while the land rapidly warms from the relatively strong springtime sun.  The following timelapse animation shows an example of this, with daytime heating causing snow showers to form and spread southeastward pushed by strong, cold winds from the northwest:

The timelapse compresses about 3 hours of midday weather into 33 seconds of video.  It was taken yesterday (29 March), and the camera was pointed to the south-southeast.  The images used in the animation were taken once every 20 seconds.  The location was just west of the Continental Divide in the Colorado Rockies.

%d bloggers like this: