Fourth snowstorm in three weeks predicted to hit East Coast

• Long-duration storm to bring heavy, wet snow in part of Northeast.

• Risk of downed trees, sporadic power outages.

• Moderate coastal flooding, beach erosion likely.

• Expect low travel secondary roads and flight delays.

A double-barreled storm will spread wet snow and travel disruptions from parts of Tennessee and Kentucky to coastal New Hampshire and Maine as winter winds down and spring begins.

Spring officially arrives at 12:15 p.m. EDT on Tuesday, March 20. The storm with wintry precipitation will straddle two seasons in the Northeast.

Long-duration snow, wintry mix for some areas

The slow forward speed of the entire storm system will bring an extended period of wet snow and/or a wintry mix from the eastern part of the Ohio Valley to the upper part of Delmarva and New Jersey from later Monday night to Wednesday.

For part of this area, the storm has the potential to bring the greatest snowfall of the winter and early spring. However, the amount of snow that accumulates on grassy areas and on vehicles will be much greater than what accumulates on roads and sidewalks.

Washington, D.C., has only received 3.7 inches of snow this season, compared to an average of 14.7 inches to this date. Baltimore has received about 54 percent of its seasonal average of 19.3 inches.

In the area from central Ohio to northern Pennsylvania, the Hudson Valley of New York state and central New England, snow may struggle to accumulate despite lower temperatures. The rate of snow in this area will tend to be much lighter than in parts of West Virginia, northern Maryland and southern Pennsylvania for example.

It is the second part of the double-barreled storm, or the coastal component, that will spread snow farther to the north in Pennsylvania, New Jersey, southeastern New York state and New England from later Tuesday night to Wednesday. This is when a slushy accumulation is most likely to occur around Philadelphia and New York City and for the snow to finally reach Boston.

RELATED: Storm brings destructive winds to US

Snow from the two storms will overlap near the Mason-Dixon Line. It is in part of this area where perhaps a foot of snow may accumulate in a narrow swath from the entire event.

Roads to stay mainly wet, while flight delays will be likely

Except where the snow falls at a furious rate, or snows at a moderate pace at night, much of the snow is likely to melt as it falls on paved surfaces like roads in urban areas.

Motorists and pedestrians should expect slippery and slushy conditions on elevated surfaces, such as bridges, overpasses and decks, and in rural areas or locations that do not receive much direct sunlight during the day.

Airline delays are likely due to deicing operations, poor visibility and a low cloud ceiling.

Prolonged winds to threaten minor damage; Moderate coastal flooding possible

In terms of wind, this will not be a powerhouse storm like the nor'easters that struck earlier this month.

However, moderately strong winds are in store for a longer duration in some cases when compared to each of the three earlier storms.

Peak gusts along the coast are projected to bet between 40 and 50 mph. A few gusts may approach this level in parts of the central and southern Appalachians by midweek.

Sporadic power outages may occur where a breeze sways trees weighed down by heavy, wet snow over the central Appalachians. Sporadic power outages are also possible near the coast where trees have been weakened by prior storms.

Motorists and pedestrians should watch for falling tree limbs in wooded areas.

Because of the 24- to 36-hour period of moderate onshore winds, moderate beach erosion and coastal flooding are likely, especially at times of high tide.

Fortunately, since the new moon occurred a couple of days ago, this storm will not be synchronized with the new or full moon, when astronomical tides are highest.

At peak, tides are likely to run 2-3 feet above average from northern Delaware to southern Maine.

Some minor back bay flooding may occur from North Carolina to New Jersey as the storm begins to move away at midweek.