Geography in the News: Nor’easters, Love or Loathe?

By Neal Lineback and Mandy Lineback Gritzner, Geography in the NewsTM

GEOGRAPHY IN THE NEWS (1118)  Neal G. Lineback and Mandy Lineback Gritzner Appalachian State University

As a prelude to winter 2014, extremely strong winter storms hit the eastern half of the United States in November. Cold interior conditions can lead to strong coastal storms throughout the winter, bringing bitter cold, high winds, rough seas and heavy snows to New England. These intense coastal storms are called nor’easters.

Skiers in New England love nor’easters, but those who make their living on the ocean would disagree.

The storms that are the sources of nor’easters are intense low-pressure cells. These particular cells track northward along the U.S. East Coast, intensifying as they reach the New England coast. The strongest and most damaging winds associated with nor’easters are the northeast winds coming from the ocean.

Winds blow inward toward low-pressure cells, spiraling counterclockwise into the cell. As the winds approach the cell, velocities increase. Drag may slow the wind over land, but wind speeds over the ocean are typically higher. Winds are named by the direction from which they blow; therefore, a wind from the northeast is called a northeast wind and in this case, a nor’easter.

Geography in the News_1074_Nor'easters (1)

Although more normal warm fronts, cold fronts and a combination of the two, called occlusions, may bring snows to New England, it is the nor’easters that New Englanders love and loathe. Two main weather phenomena must be in place for a nor’easter to occur. First, a low-pressure system associated with the Gulf Stream forms off the East Coast. The Gulf Stream is a warm ocean current of the northern Atlantic Ocean off the eastern United States. The air above the Gulf Stream warms, creating the counter-clockwise winds associated with a low-pressure cell. The low pulls warm air and moisture from the ocean, from as far as 500 to 1,000 miles (805 to 1,609 km).

Second, an Arctic high-pressure system, which has clockwise rotating winds, must be over the Midwest. As the low-pressure system moves up the East Coast, it meets the cold, arctic air blowing southward from Canada. The collision of two air masses and their associated moisture and cold air differentials produce large amounts of precipitation. Five or six feet (1.5 to 2 m) of snow are not uncommon at high elevations, such as Mt. Washington in New Hampshire’s White Mountains.

To the inland New England residents, heavy snowfalls are fairly common winter occurrences—to be expected in 6 to 20 inch (15 to 51 cm) increments three to six times each year. Skiers may love the heavy snows generated by nor’easters, but it represents one of the most dangerous and life threatening hazards to New England sailors, fishers and seamen. Prolonged high winds from the east or northeast are frightening because of extreme ocean swells. The size of ocean swells is determined by a combination of three factors: wind velocities, the length of wind duration from one direction and the size of the fetch (the distance over water that the wind passes).

Consequently, when blustery winds are from the east or northeast (the Atlantic) for a day or more, the size of ocean swells can be enormous. Many of the small-craft disasters along the New England and mid-Atlantic coasts are linked to the dangerous seas created by nor’easters.

Additional coastal hazards of nor’easters include shoreline flooding and beach erosion. As the sustained winds from the ocean create enormous swells, the winds literally push, or pile, water against the shore, creating a storm surge. Nor’easters are notorious for building storm surges, which can create major coastal damage, especially if the surges arrive onshore along with high tides.

Winter 2010 was one of the snowiest on record for many cities along the East Coast. Heavy snows began in December 2009 and continued through March 2010. Records were set in Washington, D.C. (56 in./142 cm), Baltimore (77 in./196 cm), Philadelphia (78 in./198 cm) and Atlantic City (58 in./147 cm), among others. Accompanying these heavy snows were six intense nor’easters occurring from December through March.

Winter 2014 is stacking up to be another snowy one, beginning with the bitter cold, heavy snow and blizzards that occurred across the Midwest in November. Such unseasonably cold conditions in the interior portend increased chances of major nor’easters forming over warm Atlantic waters this winter once again.

And that is Geography in the News.

Sources: GITN 1074 Nor’easters: Loved or Hated?, Maps.com, Dec. 31, 2010; GITN #244, “Nor’easters,” Mar. 19, 1993; and http://www.weather.com 

Co-authors are Neal Lineback, Appalachian State University Professor Emeritus of Geography, and Geographer Mandy Lineback Gritzner. University News Director Jane Nicholson serves as technical editor. Geography in the NewsTM is solely owned and operated by Neal Lineback for the purpose of providing geographic education to readers worldwide.

 

 

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