Name ______________________________________________ Date _______
Storm of the Century Hits the Eastern United States
From March 12 through March 15, 1993, a storm so powerful that it came to be known as the "Storm of the
Century" brought large amounts of snow, high winds, and low temperatures to the eastern United States.
During the height of the storm, snow fell at a rate of two to three inches per hour. Every major airport on the east
coast was closed at one point or another. Over three million customers were without electrical power due to fallen
trees and high winds. The National Weather Service estimated that the snowfall during this four day period was
equal to 40 days of flow on the lower Mississippi River.
STORM HIGHLIGHTS
Wind Gusts
144 MPH on Mount Washington, NH
89 MPH on Fire Island, NY
81 MPH at La Guardia Airport, NY
Snowfall Totals
56 inches on Mount LeConte, TN
43 inches in Syracuse, NY
19 inches in Asheville, NC
Low Temperatures
-12 degrees F in Burlington, VT
2 degrees in Asheville, NC
Record Low Air Pressures
962.8 millibars in Philadelphia, PA
965.5 millibars in Boston, MA
Mid-latitude cyclones are low-pressure storm systems that form along the polar front—the boundary between cold
polar air and warmer air from the middle latitudes. These storm systems are common during the winter months, but
this particular storm was unusually intense. By the time it was over, the storm had caused between 3 and 5 billion
dollars of property damage and 270 deaths. At the time, it was the fourth most costly storm of any kind in U.S.
history and by far the most costly mid-latitude cyclone.
Structure of a Mid-Latitude Storm System
The March 1993 "Storm of the Century" is a classic example of a mid-latitude low pressure cyclone. These systems
begin as weak disturbances along the polar front, where cold polar air meets warmer air from the middle latitudes.
As the air masses meet, the warmer air is pushed upward, creating a low pressure center at the surface. The
surrounding surface air begins to spiral in toward the center of the low—counterclockwise in the Northern
Hemisphere and clockwise in the Southern Hemisphere.
Examine the diagrams of the map view (top) and side view (bottom) of a low pressure storm system. Try to
visualize the system in three dimensions. Observe where different types of clouds and precipitation occur in
relationship to the leading edges of the fronts.
A cold front forms to the west of the low pressure center and a warm front forms to the east. The faster-moving cold
front will eventually overtake the warm front, squeezing the warm air trapped between them upward and forming an
occluded front. After a few days, the occluded front dissipates and the storm disappears.
1. On which side of the cold front are clouds and precipitation generally found?
2. On which side of the warm front are clouds and precipitation generally found?
Visualizing a Mid-Latitude Storm System
This animation shows the development of a typical mid-latitude storm system. Play it several times and observe the
movement of the air masses, fronts, and clouds. Think about how the Coriolis Effect creates the rotation for the
system.
Click the image to play the animation. Use the slider to examine different parts of the sequence.
Satellite Images of the Storm of the Century
The GOES 7 weather satellite captured the following color-enhanced infrared images of the March 1993 storm.
Increasing cloud density and cooler temperatures are indicated as the colors change from yellow, to red, to purple,
to blue, to white. Think about what is happening on the surface and how surface weather maps of the region would
change over the same time period.
Click the image to see the animation. Use the controls to step through the animation so you can observe the
development, movement, and dissipation of the storm system.
3. What additional information would be helpful in determining the center of the low-pressure system?
Surface Weather Observations at 0200Z
Another way to observe the progression of the storm is to examine data from ground-based weather stations.
These surface observations include barometric pressure, temperature, wind speed and direction, dew point
temperature, and precipitation. Meteorologists also note the type of weather that is occurring at the time the
observations are made.
Click each dot to view a table of surface weather observations for that city.
In the tables, the wind direction is reported as a compass reading in degrees clockwise from north. The compass
reading tells the direction from which the wind is blowing. Barometric pressure is reported in inches of mercury
(abbreviated Hg).
4. Describe the weather conditions in each of the four cities on March 13, 1993 at 0200Z.
5. What do the barometric pressures for Asheville and Concord tell you about the location of the storm relative to
these cities?
6. How do the surface weather observations compare to the colors indicated on this satellite image?
Surface Weather Observations at 1000Z
7. Describe the weather conditions in each of the four cities on March 13, 1993 at 1000Z.
8. Describe how surface weather conditions changed as the storm approached, passed through, and moved away
from these locations.
9. Based on the pattern of storm movement and the surface weather data, predict the satellite image colors over
each of these four cities on March 14, 1993 at 000Z.