The final week of 2014 will be a very chilly one across the middle of the country.
Arctic cold air of the magnitude we saw in November
took a long December vacation, but a significant pattern change has
once again opened the Arctic freezer door as 2014 comes to a close.
morning put an exclamation point on the cold snap, as the tiny
unincorporated village of Daniel, Wyoming, plummeted to 48 degrees below
zero. That wasn't the wind chill -- that was the actual temperature.
It's the coldest temperature recorded anywhere in the contiguous United
States in all of 2014.
The cold is already suspected to be the
cause of a man's death in Omaha, Nebraska, where temperatures fell below
zero Monday night.
(MORE:Snow, Cold Turn Deadly)
take a look at what we've seen, as well as the forecast. If you're a
weather geek, we'll then explore why this is happening and go into some
perspective on how warm December has been.
Tuesday Morning Lows
coldest temperatures for selected states on Tuesday morning, Dec. 30,
2014. Montana's state low was -34ºF at West Yellowstone, too close to
Wyoming's state low to plot. The next-coldest towns are plotted instead.
Current Feels-Like Temperatures
Also known as the wind chill, this is an estimate of how cold exposed skin feels due to the combination of temperature and wind.
Early Taste of Chill Arrives
The second Christmas week storm system, Winter Storm Eris, opened the Arctic gates into the U.S. for the rest of 2014 into the first few days of the new year.
morning temperatures dipped into the teens below zero in parts of
northern North Dakota, northern Minnesota and northwest Wisconsin. Wind
chills dipped as low as 38 degrees below zero at Rugby, North Dakota
early Monday. Ironically, one of the hottest locations in the U.S. in
the summer months, Thermal, California, tied a daily record low of 25
(MAPS:Actual highs and lows)
reached the double digits below zero Tuesday morning in at least 12
states from Idaho to Wisconsin (13 if one counts Mount Washington in New
Hampshire). The coldest spots were near the Wyoming-Montana border,
with 36 below zero reported at Lamar Ranger Station in Yellowstone
National Park and 34 below zero at West Yellowstone Gate in Montana.
cold stretched as far south as the Sangre de Cristo mountains of
northern New Mexico, including Taos (low of minus 6) Tuesday morning.
Wind chills from 35 to 40 degrees below zero were observed in Casper,
Laramie, and Jackson, Wyoming.
Overnight Tuesday into early
Wednesday morning, Denver plummeted to minus 19 degrees, which smashed a
116 year old record low that was set on December 30, 1898.
Incidentally, Denver only "warmed" to 1 degree on Tuesday afternoon,
which was also a new record low maximum temperature that obliterated the
previous record set in 1915.
Alliance, Nebraska also set a new record low for December 30 when the thermometer dropped to 28 degrees below zero.
Laramie, Wyoming, hit 34 below zero; at one point the city's wind chill was 55 below zero thanks to a 13-mph wind.
Wednesday morning approximately 80 percent of the U.S. land area and 68
percent of the U.S. population was at or below freezing.
The cold will ease up a bit in some areas, but linger in others this holiday week. Let's break down the forecast details.
(MORE:Expert Analysis | Winter Storm Central)
Highs vs. Average Thursday
Blue (yellow) shaded areas indicate colder (warmer) than average high temperatures for Thursday, Jan. 1.
Forecast: Bitter Cold Wind Chills
blast will persist in the Rockies, Great Basin, Plains and Upper Midwest
before easing off a bit later this week. Some of that cold air will
eventually ooze its way into at least parts of the Deep South and
Northeast in time for the New Year's holiday.
(FORECAST:10-Day Forecast Maps)
the frigid air invades, biting north winds will make it feel even
worse. The most dangerous wind chills were found in southeast Wyoming,
the Nebraska Panhandle, and northeast Colorado. These areas saw wind
chills between 40 and 55 below zero at times through Wednesday morning. (WATCH: How to Avoid Frostbite)
Here are a few other "cold highlights" in the first half of the week:
Highs in the teens or colder: Parts of the interior Northwest, northern and central Rockies, High Plains, mid-Missouri Valley, Upper Midwest
Record cold highs and lows: High Plains on Tuesday including Denver, Pueblo, Colorado, and Cheyenne, Wyoming
Subfreezing highs: As far south as West Texas, southern Oklahoma, the Ozarks, Ohio Valley, and New Jersey (Wednesday)
Subzero lows: Northern Plains, central High Plains, Upper Midwest, northern and central Rockies and Great Basin (Wednesday)
With the exception of the Rockies and southern Plains, the cold will ease in all other areas later this week.
another reinforcing arctic cold front will plunge into the northern
Plains, Upper Midwest, Great Lakes and interior Northeast this weekend,
possibly accompanied by accumulating snow in some locations.
(FORECAST:Winter Storm Frona | Daily Temperature Maps)
Western States Not Spared This Time
Southern California Freeze Alerts
Because arctic air is so cold, and therefore so
dense, it tends to move in a shallow layer close to the ground. Often
that layer of frigid air is too shallow to overcome the high elevations
of the Rocky Mountains, so the air instead plunges south and stays east
of the Rockies.
In this case, however, unusually strong high pressure is coming south with the cold air -- and at the same time, Winter Storm Frona is spinning up low pressure over the lower Colorado River Valley.
pressure difference is forcing cold winds to circulate from the high
pressure toward the low pressure, helping shove arctic air through the
This has resulted in some locally very strong
winds in the West. Winds gusted up to 78 mph Tuesday in Farmington,
Utah, and several tractor-trailers were knocked over on Interstate 15.
have gusted over 50 mph Tuesday in parts of the San Francisco Bay Area,
knocking down trees and causing power outages. A 119-mph gust was
clocked atop Mount Lincoln (elevation 8,300 feet) between Sacramento,
California, and Reno, Nevada.
This setup will also bring chilly temperatures deep into the Southwest. Even normally mild places like Los Angeles
may dip into the 30s during the first few hours of 2015 on Thursday,
flirting with daily record lows just in time for the Tournament of Roses
Parade in Pasadena. Freeze watches and warnings have been posted for a
number of areas.
Pattern Change Ahead
Why the Change?
The reason behind this pattern change should sound familiar if you remember last winter.
week, a bulge of high pressure aloft has diverted the polar jet stream
north of the Arctic Circle in Alaska and Canada's Yukon and Northwest
Territories, then southward deep into the western Lower 48 states.
is a classic arctic outbreak pattern, tapping cold air from Alaska's
interior and northwest Canada and sending it deep into the U.S. In the
colder months, when it's relatively warm in Alaska, it is probably quite
cold somewhere (if not most locations) in the Lower 48 states.
Temperature departures from average for the period of Dec. 1-20, 2014 over the Lower 48 states.
A Warm December
This expected colder end to the month will be quite a change for many, especially those in the West.
you can see in the map at left, the first roughly three weeks of
December were much warmer than average in the Rockies and Great Basin. The first two weeks of the month were the second warmest on record in Salt Lake City, topped only by December 1889, over 6 years before Utah became the 45th state admitted to the Union.
Montana set a new December record high (64 on Dec. 12). According to
the National Weather Service in Billings, Montana, it was warmer on the morning of Dec. 12 in Livingston than Atlanta, Tucson, Las Vegas and Tampa.
West Coast has been unusually mild as well. Seattle averaged 6.8
degrees warmer than average for the first three weeks of December and
recorded its 19th consecutive warmer-than-average day Monday. The cooler
weather ahead may be just enough for Seattle to avoid setting a new
record for the warmest December on record, but it will be a close call.
U.S. tallied 4,960 daily warm records (record daily highs or record
warm daily lows) from December 1 to December 28, compared to just 312
daily cold records. That's a ratio of almost 16 record highs for every
Boston's all-time record low was -18 degrees set on
Feb. 9, 1934. Once every 1-2 years the city shivers in subzero cold.
Subfreezing temperatures occur 94 days a year, there. (Photo: Darren
People living in Southern California saw some snow just
before the new year. But they may have got more than they bargained for
as some locations, like San Bernardino, snow became dangerous.
It might "never rain in Southern California," as the old Albert Hammond song goes, but it sure can snow.
snowfall even came down in areas that don't usually see wintry weather
at the lower elevations. At 1,400 feet, Lake Elsinore reported six
inches of snow to the National Weather Service, and residents were quite
surprised to wake up Wednesday to see front yards and palm trees
covered in snow. (MORE: The Latest News on Winter Storm Frona)
Winter Storm Frona's snow fell on the highways east of Los Angeles,
roads became dangerous and some drivers got stranded. Instead of passing
the time sitting inside their cars, those folks responded how people
typically do when they rarely see snow.