Coastal
Currents
Produced by the University of Delaware Sea Grant College Program & the Center for Applied Coastal Research
Northeasters
Northeaster Facts
Nearby weather systems can cause
northeasters to stall off the coast.
by Dr. Wendy Carey and Dr. Robert Dalrymple
The risk of living along the coast has changed over the
past century. Since the 1940s, and especially since the
1980s, development activity along the U.S. coastline has
exploded. As the population along the Atlantic coast
continues to increase, damage induced by coastal storms —
hurricanes and northeasters — will probably increase as well.
While hurricane season runs from June 1–November 30,
coastal storms called northeasters (or nor’easters) are a
year-round threat to coastal Delaware. Named for the direction from which their winds blow, these intense storms move
along the coast with winds blowing directly from the northeast, right off the Atlantic Ocean onto the shoreline. These
strong winds can create large waves that may exceed 20 feet
in height. The size and strength of these waves can demolish
beaches and dunes, buildings, boardwalks, and roads.
While hurricanes are unquestionably the more powerful
of the coastal storms, northeasters are more frequent in
Delaware, last longer, and impact larger areas. Although
they may threaten the Delaware shoreline at any time of
the year, northeasters usually occur during the winter.
They form around regions of low pressure and derive
their energy from the strong temperature gradients that
commonly occur when cold fronts and warm fronts collide.
A BOUT T HIS S ERIES
Coastal Currents is designed
to share timely information about
coastal hazards and the natural
processes that occur along Delaware’s shoreline. The series is
produced by the University of Delaware Sea Grant College Program
(www.ocean.udel.edu) in partnership
with UD’s Center for Applied Coastal
Research (www.coastal.udel.edu).
For more information, contact
Wendy Carey, Sea Grant Marine
Advisory Service, at
(302) 645-4258 or
[email protected].
Northeasters typically produce winds
ranging from 30 to 40
miles per hour, with
gusts that can exceed
74 miles per hour
(hurricane strength).
These storms typically
generate waves ranging
from 5 to 15 feet high,
with wave size controlled by the storm’s
duration and the storm
center’s location relative to the shoreline.
Northeasters are most
damaging when they
stall off the coast.
Typical
Northeaster
Path
H
Northeasters rotate
in a counterclockwise direction.
Northeasters
occur more often
than hurricanes
along the Delaware
coast. These lowpressure systems
typically have winds of 30 – 40 miles
per hour. While they may occur at any time
along the Delaware coast, northeasters are
most frequent from September to April.
L
Northeasters are named for the direction from which
their winds blow. As these intense storms move along
the Atlantic coast, the strongest winds blow directly from
the northeast, right off the ocean onto the shoreline. The
destructive power of a northeaster can equal or exceed
that of a hurricane along the Mid-Atlantic coast.
Flooding is a serious hazard associated with northeasters.
Tidal flooding or storm surge associated with a northeaster
can actually exceed the levels associated with a tropical
storm or hurricane in Delaware. Storm surge is the result of
water being dragged onto the shoreline by a storm’s strong
winds coupled with very low atmospheric pressure at the
storm’s center. Storm surge heights of 3 to 10 feet above
normal are especially damaging when they bracket several
tidal cycles. The torrential rainfall from northeasters also can
cause extensive flooding in both coastal and inland areas.
Historic Northeasters
Delaware’s most damaging coastal storm on record
occurred over a three-day period and five extremely high
tidal cycles on March 6–8, 1962. Winds reached speeds of
70 miles per hour. Offshore waves were recorded at higher
than 40 feet, while waves in the surf zone were reportedly
20 – 30 feet high. The storm surge associated with the
storm was 9.5 feet — the highest tide ever recorded in
Breakwater Harbor, at the mouth of Delaware Bay.
Delaware DNREC
The March 1962 northeaster is the most destructive coastal storm
on record in Delaware. It killed seven people and caused millions
of dollars in damages along the state’s coastline.
The infamous 1962 storm drowned seven people in
Delaware and caused millions of dollars in damages to
homes and businesses, highways, and beaches. Most of
the oceanfront dune system from Cape Henlopen to the
Maryland border was flattened, giving way to widespread
tidal flooding. The boardwalks in Rehoboth Beach and
Bethany Beach were destroyed, and over 1,900 homes
sustained damage from Dewey Beach to Fenwick Island.
The ocean rolled into the Inland Bays in Dewey Beach,
South Bethany Beach, and Fenwick Island.
Among the staggering recovery costs were public and private property losses estimated at $70 million ($400 million
in 2001 dollars) and beach repair costs estimated at $20 million ($114 million in 2001 dollars). Beaches, dunes, highways, homes, and utilities including power, gas, water, and
sewage treatment needed to be repaired or rebuilt.
More recently, in January and February 1998, powerful
northeasters again pounded the Delaware coast. During
these storms, sustained winds reached speeds of 40 miles
per hour, with gusts up to 60 miles per hour; wave heights
reached approximately 25 feet; and storm tide levels were
5 feet above normal. These storms caused severe beach
erosion and extensive public and private property damage
in many Delaware coastal communities.
1 for the weakest, through 5 for the most destructive.
Other factors taken into consideration include the size of
the waves, the height of the storm surge, the occurrence of
the storms with respect to the tidal cycle, and the number
of tidal cycles (duration) that the storms bracket.
With funding from Delaware Sea Grant, Professor
Robert Dalrymple, a coastal engineer affiliated with the
UD Center for Applied Coastal Research, worked with
Professor David Kriebel at the U.S. Naval Academy
and colleagues at the Delaware Emergency Management
Agency to develop a Web-based calculator to determine a
northeaster’s damage potential for the Delaware shoreline.
The Delaware Northeaster Risk Index provides an assessment of beach/dune erosion potential based on several storm
parameters. To use the calculator, visit this Web site —
www.coastal.udel.edu/faculty/rad/risk.html — and fill in
the required data, including the wave height of the storm,
the predicted (or measured) storm surge at the beach, and
the duration of the storm.
Northeasters with ratings of 1 to 2 create significant
beach erosion but are not hazardous to structures at the
beach. Class 3 or higher are dangerous storms. Class-5
storms are very dangerous and are similar to the March
1962 northeaster, which killed seven, obliterated Delaware’s sand dunes, and caused millions in damages.
The model, while generic enough in principle to apply
to other beaches, is calibrated for the Delaware shoreline.
Therefore, it is not applicable to other regions.
Preparing for a Coastal Storm
What should you do if a major storm is heading your way?
◆ Stay alert to storm advisories.
◆ Assemble a disaster preparedness kit containing
flashlights and batteries, bottled water, non-perishable
food, and prescription medicines.
◆ Be prepared to secure your home, boat, and any loose
outdoor items.
◆ Monitor weather/evacuation information on the radio or TV.
◆ Follow instructions from local officials.
Calculating a Northeaster’s Damage Potential
While many people are aware that hurricanes are
classified from Category 1 through Category 5 according
to their wind speeds and associated storm surge and damage potential, few individuals know that there is a similar
classification system for northeasters.
Coastal scientists rank northeasters into five classes
based primarily on a damage potential index ranging from
Web Sites for More Information
www.state.de.us/dema (Delaware Emergency Mgmt. Agency)
www.fema.gov (Federal Emergency Mgmt. Agency)
www.ibhs.org (Institute for Business and Home Safety)
www.redcross.org (American Red Cross)
The University of Delaware Sea Grant College Program is a member of a national network of universities
committed to research, education, and technology transfer designed to meet the changing needs of U.S. ocean,
coastal, and Great Lakes regions. The program is financially supported by the National Oceanic and Atmospheric
Administration (NOAA) in the U.S. Department of Commerce; the State of Delaware; and the University of
Delaware. For more information, please contact the UD Marine Public Education Office, Newark, DE 197163530. Phone: (302) 831-8083. E-mail: [email protected]. For other Sea Grant publications, visit our on-line
catalog at www.ocean.udel.edu/seagrant.
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