Hurricanes and the Middle Atlantic States

The East Coast is in an active hurricane cycle, which began in 1995. Active cycles
typically last 25 to 30 years. In such periods during the past, the Mid-Atlantic region had
one, two or three active years followed by two or three consecutive, and rarely four or
five, quiet years. (Going into 2009, the region has had four consecutive quiet years.)

The Middle Atlantic states have well-defined cycles of increased hurricane activity. It is
as if someone turns on and off a faucet. Previous active cycles in the region occurred
from 1876 until 1904 and from 1933 until 1961.The period from 1969 until 1979 brought
the Mid-Atlantic several notable hurricane-related floods.

The region's climate is highly cyclical. Extremes are often followed by extremes. A
drought, for example, may be followed by a hurricane-related flood. A period of years with
little generalized severe storm activity is many times followed by two or three years with
several severe storms affecting a significant part of the Mid-Atlantic. These may include
hurricanes and winter nor'easters.

Hurricanes that occur within a month or two of each other, in the same general
geographic region, often take roughly parallel tracks.

Coastal sections are due for a major hurricane. Hurricane Gloria in 1985 was the last
to cause modest to significant losses to all Mid-Atlantic shore areas. The Great Atlantic
Hurricane of 1944 was the last to cause severe damage along the shoreline from Virginia
to New Jersey. The Mid-Atlantic coast has had a dearth of major coastal hurricanes since
the early 1960s. Similar quiet periods occurred from the late 1820s until the late 1870s,
and for about three decades during the early 20th century. These less active periods
were followed by many violent hurricanes, six or more within 25 years, affecting the Mid-
Atlantic barrier islands.

On rare occasions, intense hurricanes (Category 3 at landfall in North Carolina or
while off the Mid-Atlantic coast) have produced a massive wave or series of waves
described as appearing like "tidal waves." These caused immense damage to buildings
and other structures along the shoreline. Generally, the storm waves quickly lost
momentum and losses were limited to sections within a block or two of the beach. During
the past 200 years, such events have occurred along sections of the Mid-Atlantic coast in
1821, 1878, 1938, 1944 and, perhaps, at other times. The huge waves struck as the
center of the storm made its closest passage, as easterly winds turned westerly. The
relationship of distance and position from the center varied.

Interior sections are due for a highly destructive hurricane-related windstorm.
Hurricane Hazel in 1954 was the last tropical cyclone to carry actual hurricane-force winds
through a large section of the Mid-Atlantic interior, from Virginia to Pennsylvania. The
region's climatological history suggests that inland hurricanes such as Hazel occur about
twice each century. Similar events occurred in 1667, 1724, 1769, 1775, 1821, 1878 and
1896. Highly destructive winds generally ranged in a 50 to 100 mile band in the storm's
northeast sector, although a brief period of higher winds sometimes occurred after the
center's passage, when winds turned westerly.

The popular Saffir-Simpson hurricane intensity scale understates the potential for
wind damage in the Mid-Atlantic region. A Category 1 hurricane (sustained one-minute
winds of 74-95 mph) can be expected to do widespread Category 2 and 3-type damage.
Isolated areas may see Category 4-type losses. Leafy trees and other vegetation, less
wind-resistant structures and infrastructure, as well as, perhaps, other yet to be identified
factors are responsible for the region's wind susceptibility. Also, Saffir-Simpson estimates
of tidal surge, particular in the Chesapeake Bay region, seem understated based on
observations during Hurricane Isabel.

Rapidly advancing hurricanes, those with forward speeds greater than 30 mph, seem
to have a greater ability to deflect higher winds aloft down to the surface, mainly in the
northeastern sector (when the storm is tracking in a northerly direction). The strongest
winds are location specific. As described by an observer in Washington, DC., after the
great windstorm of September 1896, "In hundreds of instances a well constructed roof,
rafters and all, was blown off, while close by very frail structures at the same height were
uninjured." Any Category 3 or stronger hurricane making landfall from the Carolinas on
north and accelerating above 30 mph is a significant threat to bring destructive winds well
inland, particularly near the center.

'Major' hurricane Mid-Atlantic style: Meteorologists define a 'major' hurricane as
possessing at least Category 3 strength (sustained winds of at least 111 mph). Because
of the Middle Atlantic states' susceptibility to wind damage, a Category 1 hurricane
(sustained winds of 74-95 mph) tracking through interior sections will cause major
destruction. Furthermore, a tropical cyclone that stalls off the Mid-Atlantic coast for more
than a day may produce major shoreline damage even if it is something less than a
Category 3.

Tropical cyclones bring great differences in rainfall and winds over short distances.
Tropical Storm Hanna (Sept 2008), for example, dumped less than two inches of rain to
more than eight inches in the Washington, D.C., metropolitan area. Hurricane Isabel
(Sept. 2003) lashed Washington and its suburbs with peak gusts ranging from less than
50 mph to nearly 80 mph. Higher winds aloft reached the surface unevenly.

When evaluating the severe weather risk associated with a hurricane, it is important to
consider the possibility of violent storms in the air mass ahead of the tropical cyclone, in
adjacent weather systems, and in the air mass behind. The worst weather may occur
indirectly, outside the hurricane's circulation, sometimes days ahead or days afterward.

The total number of drownings from hurricanes that remain offshore with little or no
effect on land exceeds those from bigger, well-publicized, storms. So says Jay Mann,
managing editor of the Beachcomber, Long Beach Island, N.J., and a long-time resident of
the shore. Rip currents are to blame. They may form when a hurricane comes within
1,000 miles of the Mid-Atlantic coast. A sprawling hurricane will have the waters churning
at 500 miles. The ocean claims lives during what appears to be perfect beach conditions.
Often, a swimmer doesn't realize he is in a rip current until his strongest efforts fail to
bring him closer to shore.

The Mid-Atlantic region boasts some of the most intense short-term downpours on
earth. Some are related to tropical cyclones. Hurricane Camille, for example, dumped
more than 27 inches of rain on sections of Nelson County, Va., within about five hours in
August 1969. Thunderstorms stalled by a hurricane off the New Jersey coast bucketed
Ewan, N.J., (just 20 miles south of Philadelphia) with more than 22 inches in about 10
hours during September 1940.

On rare occasions, for unknown reasons, some remnant hurricane systems have
regenerated while the center was over land. All such incidents have been heralded by a
surge in rainfall intensity. Some examples include hurricanes Camille (1969), Agnes
(1972) and Gaston (2004).

A hurricane deluge is of particular concern in mountainous areas. Steep slopes in
mountainous sections allow rapid runoff. An extreme event, such as occurred with
Hurricane Camille, can liquefy the soil generating deadly mud flows. Meanwhile, Mid-
Atlantic urban sections, often situated on hilly terrain, are at risk of flash flooding.
Concrete, asphalt and other impervious surfaces reduce the absorption of rainwater,
increasing runoff. The monsoonal downpours of a tropical cyclone can quickly turn
destructive and deadly, as occurred with Hurricane Gaston in 2004 when it pounded the
Richmond, Va., metropolitan area with rainfall totals that topped 10 inches.

Remnant systems tracking through the Mid-Atlantic region may spawn tornadoes,
particularly in the northeastern sector (if tracking in a northerly direction). They are
generally short-lived, with intermittent tracks usually less than five miles. Pinpointing
where a tornado will touch down is beyond our present knowledge. Although most have
occurred during daylight, a considerable number have prowled at night.

       Jay Mann of Long Beach Island, New Jersey, minces no words when discussing hurricanes and rip currents.
      “Rip currents are insidious,” said Mann, a long-time resident of the shore and rip current expert. “People caught in
strong rips like those produced by a hurricane are amazed by how quickly they find themselves in deeper water, well
away from the beach.”
       During the past half-century more people have died in the Middle Atlantic states from hurricanes whose circulation
never reached shore than from those that pummeled the coast. Sprawling hurricanes can produce groundswells that
travel out a thousand miles or more. Even during a summer when tropical cyclones give the East Coast a wide berth,
beach-goers can expect periods when venturing into the ocean is treacherous.
       “There’s almost a 100 percent chance we will be affected by hurricane swells this summer,” Mann said, “and less
than a 10 percent chance we will get hit by a hurricane.”
       Rip currents are powerful, channeled currents of water flowing away from the shore. They typically extend from the
shoreline, through the surf zone, and past the lines of breaking waves. Rips are usually caused by onshore winds and
associated surf or by the interaction of the ocean and man-made structures like jetties, but hurricane swells are the
most potent rip generators.
      Several factors make hurricane-related rip currents deceptively treacherous.
      The strength and number of hurricanes generally peak during the summer when shore areas are crowded.
Vacationers can’t wait to plunge into the inviting ocean under a warm summer sun. A hurricane hundreds of miles at
sea, perhaps no threat to strike the Middle Atlantic coast, is usually out of sight and mind. It does not get the media
attention of an oncoming storm. The public associates hurricane threats with hurricane circulation. Rip-producing swells
spread over a much greater area.
      A groundswell may be miles long as it approaches shore but not particularly high. Unless the swells encounter winds
near shore, they may not have foaming whitecaps. Nevertheless, a three-foot high hurricane-related groundswell carries
more power, energy and water than a similarly-sized normal wave.
       “Hurricane swells are the survivors of a hurricane’s strongest waves,” said Mann. “They are the most powerful
waves and important developer of rip currents out there.”
       The large volume of water crashing on shore means a large volume returning to sea. Even excellent swimmers
have drowned when caught in the return flow.
       Hurricane generated waves may arrive in groups separated by minutes of innocuous, local waves. A swimmer
venturing into the surf during a lull can quickly get into trouble once a series of groundswells arrive.
       Adding to the threat: Many people, unfamiliar with the ways of the ocean or, simply misjudging their swimming
ability, have no experience dealing with rip currents. Unable to make progress back to shore and uncertain why, they
panic and quickly tire.
      “You can’t believe how many people have drowned because they didn’t raise their hands over their heads or in
other ways signal for attention,” Mann said. “I tell people, ‘If you’re caught in a rip and have a question about whether
you can get back to shore, don’t wait until you’re exhausted. As soon as you feel yourself in a bind, forget about the
embarrassment factor and start signaling for help.”
      The National Weather Service offices that forecast for coastal sections issue rip current advisories using a scaled
likelihood of low, medium or high. There are also “enhanced risk” warnings. These typically accompany hurricane-
related swells and indicate a greater likelihood of particularly powerful rip currents.
      Jim Eberwine, the rip current specialist at the National Weather Service office in Mt. Holly, N.J., works with
information from coastal observers such as Mann, monitors buoy data and analyzes weather features to create daily rip
current outlooks for New Jersey and Delaware during the late spring and summer. Hurricanes create a special challenge.
      “We want to issue something that warns of serious conditions in the water but does not scare people away from the
beach,” said Eberwine.
      He has observed the deadly effects of obscure hurricanes that remained well offshore. Felix, for example, remained
hundreds of miles away from land as it meandered off the U.S. East Coast in 1995, but produced rip currents that
drowned more than a dozen swimmers.
       “Rip currents are a sneaky part of the storm that many people aren’t aware of until it’s too late,” said Eberwine, who
describes the rips as “a treadmill that you can’t turn off.”
       His advice to beach goers: “A rip current savvy person is one that checks with the beach patrols about the
conditions, swims on guarded beaches and never alone or at night.”
      Eberwine added, “The worst thing is a family of six coming to the beach and going home a family of five.”

      For more information on rip currents, visit www.ripcurrents.noaa.gov.

Rip Currents Are A Hurricane’s Hidden Menace

Hurricanes and the Middle Atlantic States includes the following observations: