Snowed in and iced over: North America and U.S. about as frozen as ever so late in winter


NOAA/NASA Suomi-NPP satellite image from March 4, 2014, courtesy of NOAA Satellite and Information Service

Repeated blasts of frigid air since January have transformed significant parts of the U.S. into Arctic-like territory. And, even though the calendar says March, it could easily be mistaken for the dead of winter.  By multiple metrics, the amount of snow and ice over the  Great Lakes, Lower 48 states, and North America are in historic territory.

Great Lakes ice reaches second highest extent on record

By rough approximation, there have been seven arctic outbreaks (when U.S. average temperatures dipped to 6 C or more colder than normal) this winter and two since late February. Each and every one of these arctic excursions have hit the Great Lakes head on, and the ice extent has closed in on unrivaled levels.


Temperature difference from average in Lower 48 states, December 1 through early March (WeatherBell.com)

The Great Lakes nearly froze over entirely in mid-February, when ice cover grew to nearly 90 percent – the most since 1994, according to Brian Jackson, an analyst at the National Ice Center in Suitland, Md. Then, during a brief thaw, the ice extent dropped back to 61 percent coverage later in the month, NOAA data show.

But following back to back cold snaps in late February and to begin March, the ice extent rapidly rebounded to 91 percent, the most since February 19, 1979’s record-setting 95 percent coverage, Jackson said.  “Pretty much all of the lakes are frozen over besides Ontario,” he  said.


(NOAA National Ice Center)

Lake Michigan’s ice cover reached 92.45 percent Tuesday, Jackson said, comparable to previous record high levels in 1976, 1979, and 1994.


Lake Michigan maximum ice cover, 1973-2013, does not include this year (NOAA)

Could the Great Lakes, collectively, challenge the 1979 coverage record (records began in 1973)?

“They might expand slightly, but Ontario is the only Lake that has much room to grow, and it’s going to get warmer there this weekend,” Jackson said. “Today or tomorrow is about as high as they’re going to get and probably not more than about 92 percent.”

Population centers adjacent to the Lakes have endured a punishing winter. In Marquette, Michigan, the air temperature has only exceeded the freezing mark twice since December 5.  Detroit is having its coldest winter in 36 years and snowiest in 133. Chicago, meanwhile, is having its 4th snowiest winter on record.

North America snow cover: third highest so late in season

The same late winter arctic outbreaks that have iced over the Great Lakes have primed the air for snow deep into the Lower 48 states.  NOAA reported Tuesday that snow cover over North America reached its third highest level so late in the season.

 

More than half of Lower 48 covered in snow March 4 and 5 – most in 10 years

In the Lower 48 states on Tuesday, snow covered 53.9 percent of the ground according to NOAA’s National Snow Analyses Web site  – the most in 10 years of records for the date. That number dropped slightly to 50.9 percent as of today – but is still unsurpassed in the short 10-year record.


Snow cover and depth on March 5 (NOAA)

The Earth, overall, is warm – especially the Arctic

As frozen as large parts of North America are and have been, they are not reflective of the climate of the globe and Northern Hemisphere.

Both the Northern Hemisphere and global temperature as of today are warmer than the modern average (1979-2000), according to the University of Maine’s Climate Change Institute.


Temperatures around the globe difference from 1981-2000 average (University of Maine Climate Institute)

The Arctic is especially warm, about 6.5 degrees F above the 1979-2000 average. The extent of Arctic sea ice is near a record low for this time of year, and about two standard deviations below the 1981-2000 average.


Arctic sea ice extent on March 4 compared to 1981-2000 normal (National Snow and Ice Data Center)

This winter’s behavior fits into hypothesis that disproportionate greenhouse gas-induced warming in the Arctic may be displacing cold air into continental North America – the so-called “warm Arctic, cold continent” paradox. For further reading on this controversial idea, see:

Researcher defends work linking Arctic warming and extreme weather

Arctic warming, jet stream coupling may mean another winter of extreme storms and cold air outbreaks for eastern U.S.

Scientists: Don’t make “extreme cold” centerpiece of global warming argument

Confronting the exploitation of extreme weather events in global warming reporting

Jason is currently the Washington Post’s weather editor. A native Washingtonian, Jason has been a weather enthusiast since age 10.
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