Extreme Cold Wave Invades Eastern Half of U.S.

A remarkable Arctic cold blast--the most severe since 1996 or 1994 in much of the U.S.--is smashing daily low temperature records across the Midwest, Southeast, Mid-Atlantic, and Northeast today. The counter-clockwise flow of air around powerful Winter Storm Ion, a 961 mb low centered just east of Hudson Bay at 9 am EST, is pushing frigid air from northern Canada deep into the U.S., bringing freezing temperatures as far south as Central Florida. Strong winds of 15 - 25 mph are accompanying the cold blast, and have brought dangerously cold wind chills of -30°F or lower to at least nineteen states. The coldest winds chills on Tuesday morning were over Southern Michigan, Northeast Indiana, Northwest Ohio, and Southern Ontario. The temperature in Detroit bottomed out at -14° on Tuesday morning--their 16th coldest day in recorded history--and the wind chill hit a remarkable -41°. The high temperature in Detroit on Tuesday is expected to remain below zero; the city's list of days with a high temperature below zero is a short one, with only three such days in recorded history. The cold air has eased some in Chicago, which had a low temperature Tuesday morning of -11°. Chicago's high temperature hit -1° on Monday; the noontime temperature on Monday was a remarkable -14°F, the 7th coldest noontime temperature ever measured in the Windy City. From the 10 EST Tuesday NWS Storm Summary, here are the coldest wind chill readings observed so far in the cold wave:

Comertown, MT: -63
Rolla, ND: -60
Glenwood, MN: -56
Summit, SD: -56
Waupaca, WI: -56
Ironwood, MI: -54
Mount Mitchell, NC: -50
Dubuque, IA: -49
Moline, IL: -46
Toledo, OH: -45
Ingalls Field, VA: -45
Valparaiso, IN: -44
Canaan Heights, WV: -44
Brownlee, NE: -43
Clarion, PA: -42
Oakland, MD: -41
Jamestown, NY: -38
Garden City, KS: -33
St. Charles, MO: -31


Figure 1. A frigid morning in the Windy City: Chicago seen from the air on January 7, 2014, after the low temperature hit -11°F. Image credit: Hank Cain

Worst weather of the day: Buffalo, NY
My vote for worst weather of the day goes to Buffalo, New York, where heavy snow was falling at 9 am with a temperature of -6°F. West winds of 24 mph gusting to 33 mph created a dangerously cold wind chill of -32°, and a wind gust of 60 mph was recorded at 3:26 am. West-southwest winds blowing along the length of Lake Erie are creating an epic lake effect blizzard in the Buffalo region, which may see snow accumulations of up to three feet before the storm ends on Wednesday. An ice jam has also formed on the Niagara River, leading to issuance of a flash flood warning for low-lying areas along the river.


Figure 2. A cold day on Lake Ontario. Sea smoke is visible over the lake in this shot taken three miles west of Pultneyville, NY, on January 7, 2014. The outside air temp was 1°F. Image credit: wunderphotographer JACKMAY52.


Figure 3. A cold day in the Great Lakes: Arctic air flowing over the Great Lakes on January 6, 2014 creates bands of lake-effect snow snows over and in the lee of the lakes. Image credit: NASA.

Weather whiplash in New York City
New York City is enduring a classic case of weather whiplash due to this week's wild weather. Freezing rain on Sunday morning caused a Delta flight to skid off a runway at JFK airport. But on Monday morning, a surge of warm air riding northeastwards in advance of Winter Storm Ion boosted the temperature in the Big Apple to 55°. The cold front associated with Ion passed though the city Monday afternoon, allowing the low temperature on Tuesday morning to plummet to 4°, beating the record for the date of 6° set in 1896.

The culprit: cold air from Canada and the polar vortex
In the winter, the 24-hour darkness over the snow and ice-covered polar regions allows a huge dome of cold air to form. This cold air increases the difference in temperature between the pole and the Equator, and leads to an intensification of the strong upper-level winds of the jet stream. The strong jet stream winds act to isolate the polar regions from intrusions of warmer air, creating a "polar vortex" of frigid counter-clockwise swirling air over the Arctic. The chaotic flow of the air in the polar vortex sometimes allows a large dip (a sharp trough of low pressure) to form in the jet stream over North America, allowing the Arctic air that had been steadily cooling in the northern reaches of Canada in areas with 24-hour darkness to spill southwards deep into the United States. In theory, the 1.5°F increase in global surface temperatures that Earth has experienced since 1880 due to global warming should reduce the frequency of 1-in-20 year extreme cold weather events like the current one. However, it is possible that climate change could alter jet stream circulation patterns in a way that could increase the incidence of unusual jet stream "kinks" that allow cold air to spill southwards over the Eastern U.S., a topic I have blogged about extensively, and plan to say more about later this week.


Video 1. I appeared on Democracy Now this morning to discuss the cold wave, the polar vortex, and possible linkages between climate change and wild jet stream behavior.


Figure 4. From wunderground's Jet Stream page, we see the large dip in the jet stream over the U.S. responsible for this week's extreme Arctic air outbreak.

Siberians agree: North American winters are impressive!
The last time I experienced weather this cold was on January 18, 1994. I walked across the University of Michigan campus in Ann Arbor that evening in bitter cold temperatures of ten below zero, driving winds, and lake effect snow--which the road salt had absolutely no effect on. I made it to Hill Auditorium to hear a concert by the Siberian throat singers of Tuva. After performing one of their songs that was sung in their native language, the singers explained through a translator that the lyrics described the story of their epic voyage that day from Dayton, Ohio northwards on I-75 to Michigan in a blinding snow storm with visibilities near zero and intensely cold temperatures. Their vehicle spun out into the ditch, but they were able to push it out and make it to the concert on time. "Siberia is known for its brutal winters," the translator said, "but North American winters are just as impressive!" The next morning the temperature bottomed out at -20° in Detroit, the third coldest reading in city history.

Winter storm Christina (formerly Hercules) pounds the UK with huge waves
The winter storm (dubbed "Hercules") that hit the U.S. last week morphed into a massive 950 mb low pressure system to the east of the UK on Monday. The storm, called "Christina" by the Free University of Berlin, generated huge waves of up to 8 meters (27 feet) that battered the southwest coasts of the UK on Monday, causing damaging coastal flooding, according to the BBC. Huge waves from the storm also battered Portugal, injuring four and damaging about two dozen cars. The unusually contorted jet stream pattern associated with Christina pulled warm air to the north over Western Europe on Monday. According to weather records researcher Maximiliano Herrera, Amsterdam had its warmest January day on record Monday: 14°C (57°F), and the temperature hit a sizzling 26.2°C (79°F) in Murcia, Tocino Bridge Station, Spain--not bad for the core of winter!


Video 2. Impressive waves from Winter Storm Christina (formerly "Hercules") pound the UK on Monday, January 6, 2014.

Jeff Masters