How is the 2019 tornado season shaping up so far? Both March and April saw higher than average tornado report totals, so what does that mean for May and June? It doesn’t necessarily mean that the high number of reports will continue. Read on to learn more…
According to the National Oceanic and Atmospheric Administration (NOAA), there were 145 tornadoes reported in March and 277 reported in April. The National Weather Service is still working to confirm the actual number of tornadoes that occurred. The combined total of reported tornadoes in March and April is 422, which is above both the three-year average of 272 and the 20-year average of 273. If there were in fact 277 tornadoes in April, it would mark the highest tornado count since April 2011, when a staggering 758 tornadoes touched down. The average number of tornadoes for April alone is 192 (spanning the years 1998 to 2017).
The weather pattern so far has been ideal for tornado formation, contributing to the higher numbers of reports in March and April. Prime tornado conditions occur when warm, moist air, such as that from the Gulf of Mexico, collides with cold, dry air. This causes thunderstorms, which generate tornadoes when the warm air rises through cold air cold air to create updrafts, which can begin to rotate if winds vary sharply. As the updraft draws in more air, it becomes stronger. Eventually, water droplets in the warm, moist air form a funnel cloud. Once the funnel cloud touches the ground, it is considered a tornado.
Tornadoes can vary in strength, but the most violent are generated from supercell thunderstorms. Less than one percent of all thunderstorms become supercells, and not every supercell generates a tornado. Although they can occur at any time, the most common time of day for tornadoes to form is late afternoon. Generally by this time the sun has heated the ground and atmosphere sufficiently for thunderstorms to form.
Peak tornado activity generally occurs in May, when the conditions for tornadoes are ideal. The geographic area at the highest risk is the Plains, including large swaths of Oklahoma, Kansas, Nebraska, and Iowa. There is also a significant risk for Texas and Southern states such as Alabama and Mississippi. However, just because high numbers of tornadoes were reported in March and April does not equate to high numbers for the rest of the season. In fact, there is no correlation between an active early spring and an active May or June.
