Severe Weather Warnings & Radar

When severe weather strikes, it is important to have some notice so you and your family can take cover. Thanks to advanced warning systems made possible by weather radar technology, many people have a heads up when severe weather approaches. Using radar, the National Weather Service is able to interpret weather patterns and predict weather events with some degree of accuracy. Depending on what the radar detects, one of several severe weather warnings may result.

Severe Thunderstorms

• When Doppler radar systems used for weather forecasting detect a severe thunderstorm, the area in the immediate path of the storm is sent a severe thunderstorm warning. According to the National Oceanic and Atmospheric Administration website, a severe thunderstorm warning is issued when a storm system producing wind gusts faster than 58 miles per hour or hail that is 1 inch in diameter or larger is indicated. The conditions may be detected by radar or confirmed by someone on the ground in the storm area. These warnings are generally preceded by a severe thunderstorm watch, which means conditions are favorable for this type of storm. The warning itself averages 30 to 60 minutes long and usually covers an entire county.

Flash Flooding

• When there is an event or significant heavy rainfall to warrant it, the National Weather Service will issue a flash flood warning. Flash flooding happens when there is a rapid rise in small creeks and streams that may result in flooding or mudslides. These warnings are generally two to three hours long and cover one county at a time.

Tornadoes

• Tornadoes are among nature's most violent storms. These twisting storms can pack winds faster than 300 miles per hour, toss automobiles or other large items long distances and destroy an entire building in seconds. When weather radars detect rotation in a storm, when a spotter has seen a tornado personally or even when there is a high likelihood that a storm will produce a tornado, the warning is issued so people in the path of the storm can prepare properly.

Hurricanes

• Hurricane warnings usually come far earlier than other storm warnings. This is because of their somewhat predictable patterns of movement and the time it takes them to reach land after forming many miles away. Hurricane force winds are sustained winds in excess of 74 miles per hour. When radar equipment detects these conditions in a hurricane and plots the path of the storm, the warning is generally issued at least 36 hours before the arrival of tropical storm force winds.

How Radar Works

• Doppler radar detects information from a storm by sending out light and radio waves to detect the features of the approaching storm. It can track the movement, speed, severity and level of precipitation or winds in a storm and can detect frequency of lightning and other elements such as rotation.