It's about time: winter is finally on its way out and warmer temperatures are just around the corner. We still have another week or two of cold weather to get through in the east, but that's amateur hour compared to the past three months. This winter was like a weird, climatic rap feud between east and west.
When it comes to weather data, winter ended and spring began at midnight on March 1. Meteorological seasons are different from astronomical seasons. The latter is what we're all familiar with—when the sun's direct rays are over the equator, it's the autumnal/vernal equinox, when it hits the tropic of cancer...you know the routine. Meteorological seasons make more sense, and they're broken up into even three-month periods. Using this system, winter lasts from December 1 through February 28 (or 29), spring is from March 1 until May 31, and so on.
The National Climatic Data Center (NCDC) is still compiling numbers from thousands of weather stations around the United States, and they won't release their full report on winter for at least another few weeks. The one thing we do know is that the contiguous United States will wind up warmer-than-average and drier-than-average for the season. That might come as a surprise to folks in the East (whose parkas have fused to their skin by now), but it's mostly because of that landmass west of the Rockies called the Western United States. Forget about them? Most people do.
The chart at the top of this post shows how far the average daily temperature for winter departed from average. The "average daily temperature" is the average of the day's high and low—if the high was 76°F and the low was 56°F, the average daily temperature was 66°F. The average daily temperature for winter is just the average of the averages (all 90 days averaged together), and the chart above shows how far they deviated from normal (using 1981-2010 as the baseline).
Here's the chart again so you don't have to keep scrolling up:
The numbers are striking when you organize them from warm to cold. Every city that was warmer than average lies in the western United States (except for Miami, of course), and every city that was cooler than average lies in the eastern United States. Of course, these aren't all of the cities in these areas, but they're spaced far enough apart to show the basic, sharp trend between the warm west and the cold east.
Cities in New England and around the Great Lakes were the coldest, with the season's average daily temperature falling more than four degrees Fahrenheit below the 30-year normal. Surprisingly, none of the major cities on the cold side of this list saw their coldest winters on record. Many of these reporting stations have records dating back to the early 1900s, and the closest any of them get is in the top ten. Buffalo saw its fourth coldest winter on record, Bangor its sixth, Boston its eighth, Detroit its ninth.
On the other side of the country, records went down in flames. Many cities west of the Rockies saw temperatures far above normal for most of the winter, and that resulted in most cities shattering their all-time warmest winters on record. Among the cities (just on this list) that saw their warmest winters ever recorded are Portland, Medford, Seattle, Sacramento, Reno, Las Vegas, Fresno, and San Francisco. If I had room, I'd have included Salt Lake City and Tucson as having their warmest winters on record. Phoenix came within one-tenth of one degree of tying its all-time record, and San Diego tied for second with the winter of 1980-81.
Why did this happen? Thank the jet stream. For much of the winter, the jet stream has looked something like this:
We've seen that general pattern of a huge ridge of high pressure in the western United States/Canada and a huge trough of low pressure over the eastern United States/Canada time and time again since pretty much the beginning of the year. Ridges of high pressure foster warm, dry conditions, while troughs allow storm systems to develop and drag down cold air from the Arctic.
The difference between this year and last year in the eastern half of the United States, at least, lies in the dispersion of cold air. It got cold in many spots of the country last year, sure, but the worst of the cold was focused on the Upper Midwest and the Great Lakes.
A look at the average daily temperatures' departure from normal last winter versus this winter tells the story of the cold air. It was brutal—brutal!—in the Midwest last year. Minneapolis saw its second coldest winter ever recorded, and Chicago cracked the top five with its fourth coldest. Compare that data to this year, and you'll see that the cold air stayed a little farther to the east and a little more dispersed than the intense polarvortexmageddon we went through last year.
Much of the ugly data from winter came in the last couple of weeks of February, when a ridiculously cold shot of air from Canada dipped deep into the eastern half of the country. Temperatures here in central North Carolina (where The Vane is bravely based) dipped to -7°F one morning during the coldest of the cold. It was the second-coldest temperature ever recorded in my town since records began in 1901.
I wrote a post on February 11 titled "This Winter Hasn't Been as Bad as It Sounds," which compiled data for the winter up to that point (before the last, epic cold snap). Bad is a relative term, and in hindsight, I probably should have used "cold." The warm and dry weather in the west is extremely bad.
For the east, it wasn't as cold as it could have been and has been in the past. The weather was much colder than many cities have seen in years—and some of us younger folks have ever seen, period—but people often remember things by their worse. The 1992 Atlantic hurricane season wasn't all that bad, on the whole, except for that one storm named Andrew. 2013 had one of the lowest tornado counts on record, so it wasn't so bad, aside from that EF-5 tornado that leveled much of Moore, Oklahoma. Those are extreme examples, of course, but many people will remember this winter for unimaginable amounts of snow that buried Boston and surrounding areas, or the days-long periods of temperatures at or below freezing (and even at or below zero in many spots).
Folks in the western United States will remember the winter as the warmest they can remember. Depending on their level of self-awareness, some westerners will declare this winter absolutely gorgeous, while others will acknowledge it for the slow-motion drought and impending fire disaster that it really is. The drought keeps getting worse, and drought breeds drought in the feedback cycle from hell. Warm, dry air sitting over parched ground and dead vegetation will lead to a rough fire season if the pattern doesn't change in the next month or two.
In the grand scheme of things, we may have frozen our butts off on the East Coast for a few weeks of the season, but the West Coast borrowed their "nice" weather on credit. If history is any guide, we'll remember this winter as being worse out west because of the interest they'll have to pay over the summer.
We have to get through the next week or two, but it will start to warm up in the eastern United States, and god willing, it will start to rain out west over the next few months. Let's see how well this spring treats us.