ection 5
Cyclonic weather disturbances are the most common mid-latitude weather pattern. This
type of disturbance occurs in all seasons, although they are more vigorous in the late fall
to early spring. Examples of the mid-latitude cyclone cloud shield were given in figures 2
(page 12), 4a (page 15), 14a (page 26), 27d (page 41), and 36a (page 52). The devel-
opment of these systems can be explained by the interaction of low-level temperature
gradients with disturbances in upper level winds and accelerations in the jet stre a m.
Other weather-making systems that can be observed by satellite in the mid-latitudes are
of an entirely diff e rent scale and form. These non-standard events have geographic and
season patterns that make them useful for study during the school year.
In the fall and winter months, strong cyclonic storms develop rapidly off the East Coast
of the United States. These coastal storms, often called northeasters, are a peculiar type
of cyclonic disturbance. They occur most often in the winter months and are associat-
ed with heavy snowfall events along the East Coast. These storms initially develop as a
small wave in the eastern Gulf of Mexico or along the southeastern coast of the United
States. Like other cyclonic disturbances, these coastal storms are associated with low
level temperature gradients as well as disturbances in upper level winds and accelera-
tions in the jet stream. What is peculiar about these storms is the speed with which
they develop. In figures 37–39 (pages 55 and 56), the development of a strong coastal
storm is shown over a 24 hour period. Note that the circulation around the center of
the storm is very intense. Note also the presence of a mature extratropical cyclone off
the northwest coast of the United States.
f i g u re 37. Time series of coastal storm development.
GOES image, March 1, 1994, 0300 CST
image courtesy of M. Ramamurt h y, University of Illinois, Urbana/Champaign
AD D I T I O N A L CO M M O N
WE AT H E R PAT T E R N S
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