Geoscience Reference
In-Depth Information
Figure 8.28 Hurricane forecasting.
As tropical systems evolve, atmospheric scientists at the National
Hurricane Center run statistical models based on known conditions to project the strength and path of
a storm forward through time. This forecast cone illustrates the projected path of Tropical Storm Gustav
several days forward from August 29, 2008. Note that the estimated location of the storms center widens
with time, reflecting increased statistical uncertainty. Gustav ultimately made landfall as a Category 2
storm in western Louisiana. Given this forecast, approximately 3 million people successfully evacuated
before the storm arrived.
accurate hurricane forecasting and monitoring. The death toll
was so high in the 1900 Galveston hurricane in large part be-
cause no one knew it was coming. People living on the Atlantic
and Gulf coasts today depend on hurricane forecasts to gauge
the strength of hurricanes, where landfall will likely occur, and
the potential height of storm surge. Fortunately, in this day of
real-time satellite imagery, it is possible to monitor the develop-
ment of any individual storm as it migrates across the Atlantic
or Caribbean. As a result, forecasters at the National Hurricane
Center can predict the general path a storm will take several
days in advance and provide warning of the storm's approach to
residents in its path (Figure 8.28).
2.
Thunderstorms evolve in predictable stages, including
the cumulus stage, mature stage, and dissipating stage.
These stages are related to the upward and downward
flow of air.
3.
Strong winds, lightning, and thunder typically accom-
pany severe storms. Lightning occurs when opposing
electronic charges develop between the base of clouds
and the ground. Thunder is created by the shockwave
produced when lightning superheats the atmosphere
locally.
4.
The strongest storms associated with midlatitude
weather are tornadoes, which are localized centers of
intense low pressure that develop in association with
supercell thunderstorms.
KEY CONCEPTS TO REMEMBER ABOUT
SEVERE MIDLATITUDE AND TROPICAL
STORMS
5.
The strongest tropical storms are hurricanes, which
develop when easterly waves strengthen beyond the
depression and tropical storm phases to produce sus-
tained winds greater than 63 knots (73 mph).
1.
In general, the most severe midlatitude storms form
along strong cold fronts when warm, moist (mT) air
ahead of the front is rapidly forced aloft.
