Atmosphere And Weather

Assessing the Accuracy of Severe Weather Warning Systems



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Do you have a weather radio? Does it wake you at night with warnings or watches for counties far away from you? Do weekly tests of the Emergency Broadcast System interrupt your favorite TV show? Of course this is annoying, but it is important for the first warning against dangerous conditions.

There are eight weather warnings categories for natural occurances:

-Tornado

-Flash Flood

-Flood

-Winter Storm

-Special Marine

-Non Precipitation

-Tsunami

-Space Weather

Along with these warnings, there are different stages of warnings:

-Watch. A watch means the area is highly likely to produce the specified weather, but has not of yet. Keep a watchful eye on the weather reports and the sky.

-Warning. A warning means the weather in question has been spotted in the area, either by trained weather spotters or RADAR equipment.

Currently the National Weather Association issues warnings countywide due to storms in the area. However that trend is changing because a storm is not likely to follow, or obey county lines. Further advances in the technology area have allowed for faster reading of the storms trajectory and thus have all but eliminated the countwide warning system.

The tool that the weather association has at their disposal is RADAR which is the acronym for RAdio Detection And Ranging. This is able to detect precipitation as well as the strength of a thunderstorm since 1940. Enhancements over the years have allowed the equipment to grow in viability.

The specific RADAR used by the National Weather Service is the Weather Surveillance Radar-1988 Doppler, or the WSR-88D. The prototype was built in 1988, not the one in use. A Doppler RADAR can detect motions toward or away from the direction of the RADAR along with locating the precipitation.

Being able to detect motion has allowed forecasters a look inside thunderstorms to determine rotation or lack thereof in clouds. Rotation is the precursor to tornadoes.

The RADAR is used by emitting short burst of radio waves or pulses through a rotating antenna. Each pulse is 0.0000016 seconds in length and allows a 0.00019 second "listening period." Radio waves move at the speed of light.

However, the direction of the antenna is also recorded to further provide the distance and direction of the storm. Because the "listening period" is so quick, this can be repeated up to 1,300 times per second, further calculating the speed of the storm.

The Doppler is only transmitting for about 7 minutes each hour. The remaining time is spent in listening mode.

Weather is now on the Internet, with several stations providing a link to their RADAR information. This RADAR is color coded to the severity of the storm. Commonly there are six colors:

-Black. This is the severest of storms with an extremely high potential for tornadoes, large sized hail and high speed winds.

-Purple. A very severe storm with possibility to produce a tornado, large sized hail and high speed wind.

-Red. Severe storm with a likely hood to produce a tornado, hail with wind.

-Yellow. A thunderstorm with small hail and possibly wind.

-Green. Mainly precipitation.

-Blue. Light precipitation.

Local stations usually break into broadcasting for severe storms. Many areas have a local weather station as well. Radio stations also provide weather forecasts on a more frequent basis.

As with severe land weather, take immediate action and move to the interior of the house. If possible seek shelter in a basement or other underground structure. If not available, find a room with few to no windows and cover yourself with blankets for protection.

If a tornado is eminent, do not open windows. This is a myth and does not relieve pressure in your house.

Be informed and never take any warning lightly. Often times a tornado or other such weather is at the end of the storm after all has seemed to be quiet and still. Meteorology has made great advances in the past 50 years. Before the 1900's, predictions were often based on wives tales and the changes in behavior of animals. Although storms often spring up and give little advance warning, the technology has given us a warning on the strength of the storm. While it may not be perfect, it's the only defense against the ferocity of the forces of nature.

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