Snowflakes may fly as cold air takes over Northeast

Cold air is on the move toward the northeastern United States, and as AccuWeather meteorologists have said it would, it has helped deliver the first flakes and snowfall accumulation for some locations this week, with still more on the way.

Following what was a very warm October, a change to a colder weather pattern is unfolding this week in the Northeast. Last month, temperatures averaged 3-6 degrees Fahrenheit above normal. For example, the average temperature (cumulative highs and lows) in New York City was 62.0 F, compared to a normal of 57.9 degrees or 4.1 degrees above average.

By Tuesday night the risk of a frost or freeze extended all the way to the I-95 corridor outside of the largest urban centers, and will return again each night through most of the rest of the week.

Shorts and T-shirt weather will finally come to an end, as the pattern change will have many reaching into their closets for clothing more suitable for the fall and winter months.

People who have delayed making their winter preparations will want to expedite them sooner rather than later this week with many northeastern areas forecast to experience their lowest temperatures since April or March. The end is here for potted summer flowers and vegetable plants that have held on during the extended frost-free period.

AccuWeather meteorologists have also been tracking two potential storm systems since last week that both have an opportunity to bring some snow to the typically cold spots of the region.

The first storm already had a history of producing accumulating snow in Nebraska from Sunday night to Monday morning, according to AccuWeather Senior Storm Warning Meteorologist Brian Wimer. As much as 5 inches of snow had fallen in the North Platte, Nebraska, area by midday Monday.

That same storm drifted eastward across the Mississippi and Ohio valleys later Monday and Monday night, but rain fell in these low-elevation locations since the air was generally not cold enough for snow.

"As that storm took a northeastward turn through the Appalachians, rain mixed with and even changed over to a period of wet snow in parts of West Virginia, western Maryland and southwestern Pennsylvania early Tuesday," AccuWeather Meteorologist Brandon Buckingham said.

The same storm will be associated with a dose of cold air in its wake as a dip in the jet stream lunges for the Northeast states into Wednesday. This air will be cold enough to allow lake-effect rain and wet snow to occur from northern Michigan, northeastern Ohio, northwestern Pennsylvania and northern, central and western New York state.

Over the higher ground and away from the effects of the warm Great Lakes, a general coating to perhaps an inch or two of slushy snow can accumulate on non-paved surfaces through Wednesday. However, there could be a few pockets, where snow is more persistent, that could receive several inches of accumulation through Wednesday morning.

"There almost always seems to be some spots in the Upper Peninsula of Michigan, the highest hill tops south of Buffalo, New York, and in the Tug Hill Plateau north of Syracuse, New York that pick up 6 or 7 inches of snow in these situations," said AccuWeather Meteorologist Jake Sojda.

The major roads in the region are expected to be mainly wet in the snow areas, but some slushy and slippery conditions cannot be ruled out over the ridges and on secondary roads where there is little direct sunlight during the day.

Colder air is expected to settle over the region on Wednesday and Thursday as an area of high pressure builds eastward.

"This high-pressure area will bring temperatures more typical of late November during Wednesday and Thursday," AccuWeather Chief On-Air Meteorologist Bernie Rayno said.

High temperatures will take the biggest hit, but even nighttime lows will be a little below average. Daytime highs will be 10-15 degrees below average through Thursday. Around Washington, D.C., highs will be within a few degrees of 50, and nighttime lows will generally range from 37-40.

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This high-pressure system and the configuration of the jet stream will be key players in helping to keep a second and potentially stronger storm suppressed to the south and east at the end of the week.

If the area of high pressure moves eastward enough and the dip in the jet stream does not end up near the central Appalachians or mid-Atlantic coast, then the late-week storm should keep chugging along and avoid delivering any wintry precipitation.

"Some wet snow is likely to fall over the highest elevations of the southern Appalachians, such as Mount Mitchell and Grandfather Mountain in western North Carolina from Thursday to Thursday night," Buckingham said. These areas have already had a bit of snow in the past week, so it would not be their first snowy episode of the season.

Temperatures are forecast to trend back to near average for early November next week, forecasters say.

At the end of the first week of November, highs typically are in the low 40s in Caribou, Maine, and in the mid-50s in Boston. Farther south, they range from the mid-60s in Atlanta to the low 70s in Charleston, South Carolina.

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