Fishing

The purpose of this lesson is to provide students with a basic understanding of how

to survive severe weather. This presentation will explain the impact of severe

weather on our nation and what students can do to protect themselves from

weather disasters. The lesson describes the Emergency Alert System (EAS) - our

nations delivery system for weather and civil emergencies as well as homeland

security.

severe weather including; tornadoes, winter storms, hurricanes, droughts and heat

waves.

has a tremendous impact. The transportation, agricultural, and construction

industries are significantly affected by weather.

world. Most of this severe weather occurs in the Southeast United States.

because of it’s geographic proximity to the Gulf of Mexico, the Rocky Mountains

and the strong mid-latitude jet stream. The Gulf of Mexico supplies an abundance

of low-altitude moisture, meanwhile, dry mid-altitude air travels east from the

Rocky Mountains. When these two air masses are accompanied by a strong jet

stream, or river of fast flowing air from the west, the result can be severe

thunderstorms which producing large hail, damaging winds, flooding rains, and

tornadoes.

property. United States citizens fund (through Congress) a vast infrastructure of

weather forecasting technology. This technology is administered by the National

Weather Service (NWS).

The NWS Has 115 Doppler Radars across the country at each office. In addition

the agency jointly utilizes Doppler Radars run by the Department of Defense.

The NWS has several satellites in orbit that are able to provide various pictures of

the atmosphere. This includes Visible, Infrared, and Water Vapor to name a few.

THE NWS has an Upper Air network across the country that takes sample of the

atmosphere twice a day. An instrument called a radiosonde is released via a balloon

twice a day. Measurements including temperature, dewpoint, wind speed and

direction, and pressure are taken at various heights from the surface to over

50,000 feet. This information is sent to NCEP (National Center for Environmental

Predictions) and entered into numerical weather models that are run on super

computers.

The Automated Surface Observing System (ASOS) is part of a nationwide network

that takes real time weather measurements. This includes temperature, dewpoint,

wind speed and direction, pressure, cloud cover and height, and present weather

such as rain, snow, etc.

Each NWS office has a computer system called AWIPS that handles information

coming into and going out of the office. The system also computes local applications

for local weather occurrences. The system at each office is part of a nationwide

network.

NOAA Weather Radio (NWR) is nationwide network of radio stations that

continuously broadcasts weather information from the National Weather Service.

NWR is the backbone of the Emergency Alert System.

tornadoes.

3

knowing how to protect yourself is very important.

building.

the Mid-South is in March and April. A secondary maximum is in November.

resulting in fatalities and considerable property damage.

This slide shows the number of tornadoes that occurred in January 1999.

Fortunately, this tornado remained over rural areas. This tornado was part of a

tornado outbreak during the week of January 17, 1999.

Chicago, developed the widely used tornado classification scheme.

F4 or greater, even though F4 or greater tornadoes comprise the lowest number of

total tornadoes.

tornadoes each year.

Slide 19. A Tornado or Severe Thunderstorm watch means that conditions are

favorable for tornadoes or severe thunderstorms. It does not mean that these

weather events are occurring.

severe thunderstorm has been detected on Doppler radar or has been spotted by

an observer. Take action now.

4

tornadoes.

that sheltering in an overpass is safe led to some people losing their lives during

the May 3, 1999 tornado outbreak in Oklahoma City.

shelter from a severe storm.

hall away from glass.

school swimming pool.

supply adequate shelter.

as well as loss of life in the United States. The answer is flooding.

and how complacent people take their occurrence.

5

a typical killer flash flood. We have had similar situations in the Mid-South, most

recently in November 2001.

thunderstorm. It is based on hail size and wind speed. The amount and intensity of

lightning is not included in this definition.

Downbursts cause more damage each year than tornadoes. Downbursts are caused

by cold air, descending quickly to the ground. Downbursts can produce winds that

are equivalent to those produced by a moderate sized tornado.

thunderstorm complex.

community. Note the sharp reflectivity gradient from the strong red color to no

radar echo. The “bowing” of the radar echo indicates a strong potential for

damaging wind.

devastating and are often mistaken for tornado damage.

6

Weather Radio, commercial television and radio, as well as the internet are

excellent resources.

severe weather, civil emergencies and enemy attack. NOAA Weather Radio

provides the backbone for EAS with its tone alert capability.