• Weekend's record cold retreats as storm pumps warmth north
  • The worst of winter may be behind the U.S. East Coast

Sometimes it’s good to be on the right side of a storm system.

When that happens, winter’s sting can be replaced by a preview of spring. Just ask folks in New York City, where a record for the date of minus 1 Fahrenheit (minus 18 Celsius) gripped their world Sunday, followed by a snowstorm Monday that melted away as temperatures hit the 50s by Tuesday.

The arctic high-pressure system that dominated this past weekend moved offshore while a storm went through the Ohio Valley, said Andrew Orrison, a forecaster with the U.S. Weather Prediction Center in College Park, Maryland. These systems spin counter-clockwise in the Northern Hemisphere, so winds from the south have roared up the East Coast.

“There has been a strong return to a southerly flow transporting much warmer air to areas around New York up to Boston, ” Orrison said.

Washington had a blast of warmth as well. The temperature at Reagan National Airport went from 32 degrees at 5 a.m. Tuesday to 51 degrees at 7 a.m., according to the National Weather Service.

Wrong Side

For those on the wrong side of the storm, it’s a different story. Snow and cold spread across western Pennsylvania and New York, said Rob Carolan, a meteorologist at Hometown Forecast Services Inc in Nashua, New Hampshire. The chill and snow squalls reached up into Ontario and Quebec as well, Environment Canada said.

In addition to the storm track that helped push Boston from a daily record of minus 9 on Sunday to the mid-50s Tuesday, other influences have affected weather patterns.

The Arctic Oscillation, or fluctuating periods of high and low pressure over the pole, was in its negative phase, which pushed cold air down into the central and eastern U.S. at the end of last week and over the weekend, Carolan said. This has begun to ease back into its positive phase, which gathers the frigid air back up above the Arctic Circles, so “the cold air can’t hang around,” Carolan said.

Farewell, Cold

On top of that is El Nino, which typically means mean milder winters across the northern U.S. and has affected patterns all season. Temperatures in New York and Chicago were well above normal in December and just a bit warmer in January.

“Thanks to this super El Nino, we can’t seem to lock down a cold pattern, so every time we try -- like last week or middle January -- we’ve been able to flip back warmer fairly quickly,” Matt Rogers, president of the Commodity Weather Group LLC in Bethesda, Maryland, said in an e-mail interview. “This one is faster, thanks to a helpful inland storm track.”

While temperatures may drop to normal levels for this time of year, Rogers said there probably won’t be any severe cold for the rest of the month.

Quick cold hits are possible, “but nothing durable,” he wrote in Tuesday’s forecast. “The big picture over the next two weeks is one of seasonal to above-normal temperature ranges nationally with some fairly big transient warmings at times for the Midwest, East and South. ”

Stronger Sun

And of course, cold also has another, larger adversary: the sun. Once mid-February passes, it “gets stronger and the days lengthen three to four minutes a day,” Carolan said.

Even if things do turn a bit chilly -- and the forecast is for Central Park to have a low in the 20s Thursday -- there’s probably a good chance that the worst of the U.S. Winter of 2015-16 is behind us.

The deep freeze over the weekend “is probably going to be the coldest air mass of the season,” Carolan said. “Before you know it, you will be weeding the garden.”

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