Temperature rollercoaster may yield flood risk, one last snowstorm opportunity in northeastern US

By Alex Sosnowski, AccuWeather senior meteorologist

A powerful storm will first send a surge of warm air with rain and the risk of flooding to the northeastern United States before high winds blast cold air back into the region.

The period from late February to early March can be a quick change artist in terms of the weather, and conditions coming up in the Northeast will be a prime example.

Enough mild air will be around at the onset of the rain through Saturday night to limit any ice and snow to the ridgetops of Pennsylvania, upstate New York state and New England (north and west of the I-95 corridor from New Haven, Connecticut, to Boston).

The storm will bring a general 1-2 inches of rain to the region this weekend. While this would normally not cause any problems other than urban flooding, the combination of the rain, melting snow and soggy or frozen ground will have streams and rivers on the rise.

"In some cases, there are a few inches of water locked up in that snow and ice cover," according to AccuWeather Meteorologist Jake Sojda.

"If all of that snow were to melt quickly with the 1-2 inches of rain, it may be like a 3- to 6-inch rainstorm coming in 12-24 hours," Sojda said.

Some of that snow melted late this past week, and the rainfall this weekend will be rather brief and not heavy the entire time.

However, areas prone to flooding along unprotected areas of creeks and rivers are likely to take on water. This includes such rivers as the Potomac, Susquehanna, Delaware, Lehigh, Juniata, Raritan, Connecticut, Schuylkill and others.

During the surge of warm air from Saturday night to Sunday, temperatures are projected to climb well into the 30s in northern New England, the 40s in central New England, the 50s in the upper mid-Atlantic and the 60s in the southern mid-Atlantic.

However, people should not get used to the warmth as a dramatic change will take place from Sunday to Monday as winds howl across the region.

Gusts to hurricane force (74 mph) can occur around the eastern Great Lakes and over the ridges and through the gaps in the central Appalachians.

Gusts to 50 mph and locally higher can spread from the mountains on Sunday to the Atlantic coast later Sunday night and Monday.

Travel delays and restrictions are likely. Large limbs, trees and power lines will come down. Airline passengers may have to contend with significant turbulence.

Temperatures are forecast to plunge back to seasonable levels from Sunday night to Monday night.

The combination of wind, dry air and temperatures will send AccuWeather RealFeel® Temperatures down into the 20s, teens and single digits F over the region by Monday.

RELATED: 
AccuWeather 2019 US spring forecast 
Weekend storm to lash Midwest to Northeast with damaging winds, power outages and travel issues 
NHL Stadium Series: Rain to douse Flyers, Penguins game Saturday night in Philadelphia

Download the free AccuWeather app to view the latest forecast and advisories for your area.

What's ahead for the upcoming weeks?

Cold air will tend to grow some roots in the region from the last several days of February through the first week of March.

A quick dose of mainly light snow may pivot across northern and central areas of the Northeast during the middle of next week.

It is possible that a small lobe of the polar vortex, essentially the meteorological North Pole, may make one last lunge toward the Great Lakes region by the first weekend in March.

That polar plunge may be preceded or accompanied by one last attempt at a snowstorm along the mid-Atlantic and New England coasts between March 2 and 6, according to AccuWeather Lead Long-Range Meteorologist Paul Pastelok.

"It is not a perfect setup for a big coastal Northeast snowstorm without a blocking area of high pressure over Greenland, but it may not have to be," Pastelok said.

However, following windy and cold conditions during the first full week of March, there is a good chance the back of winter may break by the second full week of March.

"The transition to spring should be a better one this year, compared to last year, in the Northeast," Pastelok said.

While setbacks in warm weather can still occur later in March and April, especially so in the North Central states and northern New England, warm weather fans and those sick of snow and ice may be pleased over much of the Northeast with the anticipated conditions.

Spring weather may set in a little ahead of the official start on March 20 at 5:58 p.m. EDT.