A busy severe weather season ahead?

By Jared Shelton News-Press NOW meteorologist

The last severe thunderstorm to impact Northwest Missouri and Northeast Kansas took place last September, and as spring 2024 progresses, it’s only a matter of time before the next bout of severe weather strikes.

Ahead of the pending spring and summer storm season, local branches of the National Weather Service across Missouri and Kansas are observing “Severe Weather Preparedness Week.” A time for the public to brush up on knowledge and preparedness of thunderstorm-related hazards, including tornadoes, flash floods, damaging winds, hail and lightning.

Of these four phenomena, tornadoes are the least common and most elusive. The small scale and short time frame over which twisters take place make predicting exactly where they will form nearly impossible until minutes before they spiral down from a vigorous thunderstorm. With that being said, the ingredients necessary for tornadoes can be predicted more readily, providing a general idea of where tornadoes could form several hours or days in advance.

A tornado threat is not in the forecast for at least the next 7-10 days across Northwest Missouri and Northeast Kansas, but it’s not too early to speculate how busy the approaching tornado season could be for our area. A growing record of tornado climatology and better understanding of large-scale ocean atmospheric teleconnections can even be enough to make a loosely bound regional prediction, targeting when and where tornadoes are most likely to ramp up in frequency over the coming months.

Climatologically, tornado frequency peaks from mid-March to early April across the southern tier, ramping up across the Midwest and Great Plains through late April, May and early June. The shift is driven by the northward migration of Gulf of Mexico air and upper-level dynamics, which provide moisture, lift and wind shear necessary for tornado outbreaks to occur.

This year’s tornado season is not expected to significantly deviate from typical tornado climatology. However, the latter half of the season could be busier than past years across the Midwest and Great Plains, mainly due to a phase shift of the El Nino Southern Oscillation or ENSO — a cyclical pattern of ocean temperatures in the Equatorial Pacific that’s known to impact large scale weather patterns across North America.

After nearly a year in the warm phase, called El Nino, a shift to La Nina (cold phase) is now underway, a trend likely to continue as the warm season progresses. A transition toward La Nina through mid to late spring typically amplifies the upper-level jet stream across central portions of the continental U.S., creating more opportunities for regions of lift and wind shear to develop. Gulf of Mexico waters are also forecast to run warmer than normal, promoting more evaporation and ultimately better moisture availability to aid in thunderstorm development across inland regions.

Whether or not the approaching tornado season is busier than normal, it only takes one to change lives and landscapes for years to come, which is all the more reason to always have a tornado safety plan in place before storms start ramping up.