This week, one of our National Weather Service offices that covers portions of New Jersey is holding Severe Weather Awareness Week. As we get further into severe weather season, it is always important to know what a severe thunderstorm is and how to stay safe during one. So, let’s go through some severe weather basics and safety tips.
What is a severe thunderstorm?
A severe thunderstorm is defined as a thunderstorm that produces one or more of the following: hail of one inch in diameter or larger and/or wind gusts of 58 MPH or greater. Remember that both of these are minimums, as hail can far exceed one inch in diameter. In fact, on July 23, 2010, the largest hailstone ever recorded in the United States (in terms of diameter) fell in Vivian, South Dakota. The hailstone measured 8 inches in diameter, breaking the previous record of 7 inches in June 2003 in Aurora, Nebraska. That hailstone in Aurora also had a circumference of 18.75 inches, which is still the record today. You may hear your local meteorologist mention hail sizes during severe weather coverage, so it may be helpful to become familiar with this chart to get an idea of how large the hail may be.
What is the difference between a Severe Thunderstorm Watch and a Severe Thunderstorm Warning?
When a Severe Thunderstorm Watch is issued for your area, it simply means that the conditions are favorable for severe thunderstorms to occur. This does not always mean that your specific location will be impacted by a severe thunderstorm, but the possibility is there.
If you receive an alert indicating a Severe Thunderstorm WARNING, that is the time to act. The warning means that a storm has reached the severe criteria that we previously discussed and that the severe storm will impact your location.
These guidelines are true for all watches and warnings. A watch generally means that conditions are favorable for the event to occur, while a warning means that event is actively occurring or is imminent.
How can you prepare for severe thunderstorms?
There are some obvious answers to this question. The most obvious answer is to check your local forecast by watching your local news channel. There are also national weather stations that provide great severe weather coverage, but if you really want to get the local details, then local news is the best option. Of course, I highly recommend tuning in to the Rutgers WeatherWatcher forecasts for local weather details around the Rutgers campuses and New Jersey!
*NO PHONE APPS! While apps may be convenient to find out what the temperature might be on a storm-free day, they perform poorly when it comes to unsettled or severe weather days. Plus, they don’t give you the full details and the thoughts of a knowledgeable human being.
You should also be signed up for weather alerts on your phone and any other electronic devices (so, yes, this is a rare occasion where the weather app becomes handy). Don’t forget to have flashlights nearby as well!
What should you do during a severe thunderstorm?
While not always a possibility depending on your location, it is best to seek shelter inside a sturdy building during a severe storm, staying away from windows. Even if there is not a warning issued for your area, you should immediately go indoors when you hear thunder and especially see lightning. If you hear thunder, you may be close enough to a lightning strike, as lightning can strike at least 10 miles from a thunderstorm. If you are at an outdoor event, at the beach, at a park, fishing, or just relaxing in the backyard, it may be handy to buy a lightning detector. I have one myself, which can clip on to your pants. These detectors can not only count the number of lightning strikes it picks up, but they can also tell you how far away the strike was.
After a severe thunderstorm has passed, you may have a power outage. Remember to never go near fallen power lines, as they may still be live and could lead to electrocution.
To find out more about severe weather and tornado safety, you can always revisit our Severe Weather Preparedness segment that was published in 2022: https://www.youtube.com/watch?v=JwVXeoprRQ0
Stay safe and always be weather aware!