The 2021 Tornado Season May Be More Destructive Due to La Niña
If you didn’t know already, we are in a La Niña year, which typically means winter temperatures are warmer than normal in the South and cooler than normal in the North. Even with these expected patterns exceptions can exist, like when the polar vortex brought arctic temperatures and snow as far as southern Texas in mid-February.
Research shows that tornadoes and hail are more frequent during springs with La Niña. Severe weather can occur during any month of the year, but the peak activity usually falls during the months of March, April and May.
This year's tornado season could be more severe than usual across the USA, in part because of La Niña. The climate pattern called La Niña is a natural cycle marked by cooler-than-average ocean water in the central Pacific Ocean – is one of the main drivers of weather around the world, especially during the late fall, winter and early spring.
AccuWeather meteorologists said that because of La Niña, severe weather and tornado activity could abruptly fire up and rival 2011, one of the most notorious severe weather seasons, when tornadoes killed more than 550 Americans.
"The temperature of the water in the central and eastern tropical Pacific during February 2021 is similar to the La Niña pattern in February 2011," AccuWeather meteorologist Paul Pastelok said.
Tornado counts climb quickly in spring. With jet stream winds still strong and ample moisture returning north periodically, the threat of tornadoes spreads farther north.
In April, surface dew points in the 60s, or even 70s, penetrate farther north as actual temperatures sometimes climb into the 80s and 90s, supplying fuel for severe thunderstorms.
The number of severe thunderstorms can drastically increase during the months of April and May, which can also lead to an increase in the number of tornadoes that develop. AccuWeather meteorologists are predicting between 275 and 350 tornadoes will occur during the month of April alone, which could make April 2021 the third April in a row with more than 300 tornadoes.
May is typically the peak in tornado activity nationally due to the best setup of warm air, jet-stream disturbances swinging out of the Rockies and plentiful moisture east of the Rockies.
Tornado/Hail Frequency Index In these maps, purple indicates higher storm event frequency, and brown indicates lower storm event frequency. Specifics vary, but in general, springtime tornadoes and hailstorms are less frequent in the southern central United States during El Niño, and more frequent during La Niña. (NOAA Climate.gov)
Historical Weather and Climate Patterns, Offer Insight to Future Events
With all taken into consideration, meteorologists are watching for an early start to severe weather season. There are questions as to whether the cooler Gulf waters could delay the severe season, but it’s believed La Niña will be the greater influence. This pattern also lends itself to a warmer and wetter than normal pattern for the state of Ohio. The same could be said for nearby states, including Indiana, Michigan, and Kentucky.
As we all know, weather doesn’t always follow predicted patterns and not all La Niña years are alike. However, by looking at past events and climate patterns and running weather models and extended forecasts we can help business owners be informed and aware of a potentially active tornado season.