Incredibly, it’s been much colder in Chicago than in Anchorage, Alaska. On Thursday, Chicago saw a high of 10 degrees and a low of minus 2. Anchorage reported 48 for a high and 35 for a low. It’s not often in the dead of winter that the low in Anchorage, 2,847 miles to the northwest, runs 25 degrees warmer than Chicago’s high.
What’s causing this anomalous weather? It’s being driven, in part, by widespread above-normal water temperatures across the North Pacific Ocean. That huge area of relatively mild water has generated a dome of warm air in the overlying atmosphere sufficient to buckle the polar jet stream to the north of Alaska. From there, the jet stream plunges southeast into the United States, directing repeated surges of frigid air into the country.
The white-out conditions that frequently accompany lake-effect snow can be deadly. An especially intense burst of lake-effect snow that swept into northwest Indiana on Thursday afternoon contributed to a deadly accident on I-94 involving at least 16 semi-trailer trucks and possibly 7 deaths.
SOME SNOW AMOUNTS:
4.1” fell in La Porte, IN,
4.8” at Benton Harbor, MI,
4.0” in South Bend
… and the most impressive total was 6.8” near Roseland, IN in St. Joseph county, but 4.6” of that fell in just over an hour.
Those snows were in addition to 1-2 1/2 FEET of lake-effect snow that fell in those areas on Tuesday and Wednesday.
A turbulent North Pacific Ocean generated 50-foot waves, the highest in a decade, on the northern exposures of some of the Hawaiian Islands.
By Tuesday, a massive, sprawling polar air mass will have covered approximately three-quarters of the “Lower 48″, from the Rockies eastward to the Atlantic Coast and from the Canadian border south to the Gulf of Mexico.