By Alex Sosnowski, AccuWeather senior meteorologist
May 9,2017, 1:16:35PM,EDT
The weather pattern responsible for unseasonably chilly conditions, and in some cases frost, will continue over the northeastern United States into part of next week.People with outdoor plans will have to deal with conditions more typical of early April or March for an extended period. Jackets, long sleeves and blankets will continue to be put to use.
"In the Northeast, one vortex of chilly air in the jet stream will be replaced by another through early next week," according to AccuWeather Lead Long-Range Meteorologist Paul Pastelok.
The jet stream is a fast river of air at the altitude in the atmosphere where jets cruise. When the jet stream breaks off and forms a circle (vortex), cloudy, chilly, windy and showery weather can linger for days. Sometimes the pattern can produce wet snow, like what occurred over part of the Northeast this past weekend.
On the immediate back side of each vortex, where skies become clear and winds diminish, a frost or freeze can occur if the air is cold enough.
Low temperatures will range from the upper 20s F in the cold spots to the upper 40s to near 50 in the large Interstate 95 cities through midweek.
As the first chilly vortex continues to spin away and dry air invades this week, the risk of frost will continue over parts of the Northeast.
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People in the normally cold spots will need to continue to take precautions by covering tender plants or moving them indoors where possible.
Areas at risk for a frost or freeze will extend from part of the Great Lakes region to the central Appalachians and western New England early Wednesday morning.
During early Thursday morning, the overall area at risk for frost will shrink around the Great Lakes and central Appalachians but is likely to extend eastward into new territory across New England.
By Friday morning, only a few spots in upstate New York and central and northern New England will run the risk of a light frost.
A rainstorm will interrupt the frosty pattern this weekend.
The storm will cause another chilly vortex to form this weekend and perhaps linger into early next week.
"Depending on how strong the storm becomes this weekend, there is a chance it manufactures enough cold air to bring wet snow to the mountains of eastern New York state and western New England," according to AccuWeather Senior Meteorologist Henry Margusity.
The start time of the rain and possibility of snow may change as the storm responsible has not formed yet.
How quickly dry air invades the second vortex will determine the departure of showers and the extent and duration of frosty episodes next week over the interior Northeast.
The frost potential could exceed the average last date of frost in May for some locations as a result.
The weather pattern looks warmer during the latter third of May, Pastelok said, adding that how much warmer it will get is questionable this far in advance.