'Antennas are up': Forecasters monitoring East Coast Valentine's Day snowstorm potential

AccuWeather meteorologists are keeping a close eye on a new blast of Arctic air and a potential winter storm along the East Coast that may spawn from later this weekend into early next week - just in time to impact some areas on Valentine's Day.

Prior to the next wave of cold, conditions will be quite mild across the region with highs forecast to climb into the 50s F along the Atlantic Seaboard and reach the 30s and 40s over the Appalachians in the Northeast from Friday to Saturday, which will be 10-20 degrees above average. Even though the anticipated cold is expected to fall short of recent Arctic blasts, the dramatic change in temperatures could add to the shock value of the burst of wintry weather.

The transition to colder weather also could set the stage for a storm to develop, strengthen and then attempt a northward turn over the western Atlantic from later this weekend to Monday, Valentine's Day.

"The antennas are still up for an East Coast storm on Sunday and Monday," AccuWeather Chief On-Air Meteorologist Bernie Rayno said, adding that it is not yet certain how far to the north wintry precipitation, including snow, will spread. The storm's precise track will determine where snow falls, and AccuWeather forecasters are still analyzing different potential outcomes.

A dip in the northern jet stream will allow Arctic air to advance from the northern tier of the Midwest and Plains on Friday to the western Gulf of Mexico and coastal New England on Sunday morning. The forward progress of the cold air is likely to slow and perhaps stall along the southern Atlantic coast on Sunday in response to the formation of a storm nearby.

A disturbance in the southern jet stream, which will remain separate from the northern branch behind the cold, will be the feature to watch for the development of the storm.

"With enough separation in the two features, there is room for the southern feature to strengthen and allow a storm to track farther north than would occur in a typical progressive pattern," AccuWeather Lead Long-Range Meteorologist Paul Pastelok said. In a progressive pattern, storms and air masses generally move along at a steady clip across the United States, as witnessed by the parade of Alberta clippers spreading snow along the northern tier of the country this week. However, as the pattern evolves, snow or a wintry mix could spread northward along the Interstate 95 corridor of the mid-Atlantic and New England from Sunday to Monday.

If the trailing southern feature ends up following too close behind the northern dip of the jet stream, the storm that will develop will be more likely swept out to sea before moving very far to the north along the Atlantic coast. In this case, dry air would sweep in, and the zone from Washington, D.C., to Philadelphia, New York City and Boston would be spared from travel-disrupting snow or a wintry mix.

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Even if the storm does not sneak up the East Coast, a period of snow or a wintry mix may occur across portions of the Carolinas and southeastern Virginia from Sunday into early Monday. Cities such as Charlotte, North Carolina, Greenville, South Carolina, and Norfolk, Virginia, have all had a significant amount of snowfall so far this winter with 180-250% of the average seasonal snow to date.

"The pattern has the look that a banana-shaped area of high pressure may form with the cold air from northern New England to the western Gulf Coast, which is a classic setup for wintry precipitation to occur somewhere in the East even if snow potential is limited to a small area," Pastelok said.

"If it does manage to snow and accumulate from Sunday to Monday along part of the Atlantic Seaboard, warm conditions from recent days may cause some or much of the snow that falls to melt on streets and highways, especially where that occurs during the daylight hours," AccuWeather Senior Meteorologist John Feerick said.

The Arctic air is forecast to arrive regardless of how the storm behaves and will serve as another reminder that winter is not yet over. In fact, the halfway point of the season recently occurred. Average highs in mid-February range from the low to mid-20s in the northern tier of the Midwest and New England to the upper 50s in Atlanta and the mid-60s in Houston. As this next batch of cold air sweeps in this weekend, highs will dip into the single digits and teens in the northern tier to the 40s in Atlanta and the mid-50s in Houston.

"Despite the reality check, this air mass will not be as cold as those that have already invaded so far this winter, and it is only likely to last a day or two instead of several days or weeks on end," AccuWeather Senior Meteorologist Brett Anderson said.

"This could be the last significant dose of Arctic air for Texas and the southern Plains of the winter season," Pastelok said.

Additional waves of cold air will continue to sweep from the North Central states to the Northeast, but the temperature pattern will feature ups and downs, rather than many days in a row of frigid air.

AccuWeather's long-range team of meteorologists is expecting cold air to ease up across the eastern two-thirds of the nation in late February with the potential for significant warming during March.

The risk of significant winter storms, however, will not be over as pockets of cold air can still meet up with storms and produce snow.

"We still expect a regression or reversal of that moderating temperature trend toward April in the Northeast that can bring unseasonably cold conditions and perhaps a corresponding increase in the risk of wintry precipitation once again," Pastelok said.

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