It’s not a holiday, but it comes every year around mid-April: Severe Weather Awareness Week. This awareness week runs beginning Monday, April 16 to Friday, April 20 this year. This post seems to be most fitting today for those of us that are located within the Midwest with the recent bout of storms sweeping our area. In fact, the picture below is a graphic provided by our local Southeastern Minnesota television station advising the moderate risk for severe weather this evening. As we head into severe weather season, it’s important to have a refresher about the terms that we’ll be living with in the future summer months. Be safe!
Severe Thunderstorm Watch: This is issued by the National Weather Service when conditions are favorable for the development of severe thunderstorms in and close to the watch area. A severe thunderstorm by definition is a thunderstorm that produces one inch hail or larger in diameter and/or winds equal or exceed 58 miles an hour.
Severe Thunderstorm Warning: This is issued when either a severe thunderstorm is indicated by the WSR-88D radar or a spotter reports a thunderstorm producing hail one inch or larger in diameter and/or winds equal or exceed 58 miles an hour; therefore, people in the affected area should seek safe shelter immediately. Severe thunderstorms can produce tornadoes with little or no advance warning. Lightning frequency is not a criteria for issuing a severe thunderstorm warning. They are usually issued for a duration of one hour.
Tornado Watch: This is issued by the National Weather Service when conditions are favorable for the development of tornadoes in and close to the watch area. Their size can vary depending on the weather situation. They are usually issued for a duration of 4 to 8 hours. They normally are issued well in advance of the actual occurrence of severe weather. During the watch, people should review tornado safety rules and be prepared to move a place of safety if threatening weather approaches.
Tornado Warning: This is issued when a tornado is indicated by the WSR-88D radar or sighted by spotters; therefore, people in the affected area should seek safe shelter immediately. They can be issued without a Tornado Watch being already in effect. They are usually issued for a duration of around 30 minutes.
*Definitions above are provided by the National Weather Service. The weather graphic below was provided by KTTC-TV.