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Winter is about to announce itself to the eastern United States. A developing storm system — potentially the season's first nor'easter — is forecast to sweep across the Northeast late this week, bringing the first snowfall of the season to millions of Americans and a blast of cold air that will be felt by more than 160 million people. The big cities will mostly get cold rain. But inland, from the Appalachians to New England, the first snowflakes are coming.
The setup begins on Wednesday, when a wave of low pressure organises over the Ohio Valley and tracks toward the Mid-Atlantic and Northeast. By Thursday night, the first chances of snow arrive across the interior Northeast, according to forecasters at weather.com, with the heaviest impacts expected between Thursday and Saturday. Places that could see their first snowflakes of the season include Pittsburgh, Syracuse and Binghamton. The most significant snowfall is projected across northern New York, Vermont, New Hampshire and Maine, with measurable snow also possible along the Appalachian Mountains into central Pennsylvania and West Virginia.
What the big cities will get instead
If you live in Washington, New York, Philadelphia or Boston, do not expect a snow day. The Atlantic Ocean keeps the immediate coast too warm, and forecasters expect the I-95 corridor to see widespread cold rain and gusty winds rather than snow. There may be a brief transition from rain to snow as the storm departs, but accumulation along the coast is highly unlikely. What the cities will get is the cold: highs will plummet about 20 degrees from Wednesday to Friday, from Chicago all the way to Atlanta, and by the weekend overnight lows will drop into the 30s as far south as the Florida Panhandle.
The numbers behind the cold snap are striking. On Tuesday, only about 4 million Americans will be below average temperatures. By Saturday, that figure exceeds 160 million. More than 110 million people across the Northeast and surrounding areas will see afternoon temperatures stuck in the 30s and 40s, with overnight lows in the 20s in places. A deep dip in the jet stream — a trough — is dragging Canadian air south, and behind the storm, lake-effect snow bands could form as that cold air moves across the relatively warm waters of the Great Lakes.
Why forecasters are still hedging
This is a forecast, not a certainty, and the models still disagree. The American GFS model has the storm slowing to a crawl, bringing rounds of lake-effect snow to the interior Northeast and rain to the coast through the weekend and possibly into early next week. The European model moves the storm offshore faster, with rain, wind and snow inland on Friday and Saturday before it moves on. NOAA's Weather Prediction Center says there is still uncertainty in the track and expected impacts, and the exact snowfall totals and coastal winds will only come into focus as the models converge later this week.
One thing the models agree on: the cold will not last. As USA Today reported, temperatures are forecast to return to above-average levels by next week, and the nation as a whole is still on track for one of its top 10 warmest Novembers on record. Winter storm warnings are already in effect in parts of Minnesota, Idaho, Maine, Connecticut and West Virginia, and Alaska is expecting 8 to 12 inches of snow with gusts to 60 mph near the Canadian border. The season's first nor'easter is a preview, not the main event — but for millions of Americans, Thursday night will be the first time this winter they wake up to snow on the ground.
Sources: USA Today; weather.com. Snowfall totals and the storm track remain forecast-dependent and may change.