Update: Friday, April 27
April 26 has come and gone without any tornado activity in the Sooner state this calendar year. It is now officially the longest Oklahoma has gone without an observed tornado in recorded history to start the year.
Severe thunderstorms are unlikely in the region for the rest of the month so the state should remain tornado-free into May for the first time. There is some suggestion some severe storms could erupt in the Southern Plains next Wednesday into Thursday (May 2-3), which appears to be the first opportunity to end the tornado drought.
Original post from Wednesday
Across much of the Lower 48, winter just won’t quit. It’s about to be May, but temperatures are running as much as 20 degrees below normal, snow is still falling and plants are slow to come out of their wintertime slumber. The continued onslaught of wintry weather has kept spring things at bay — things like tornadoes.
It has been so quiet, Oklahoma is about to set a record for the latest first tornado of the year.
On average, about 12 tornadoes form in Oklahoma during April. It’s typically the state with the third most tornadoes annually, as well as home to some of the highest tornado odds per square mile. The longest Oklahoma has gone without a tornado was until April 26 in 1962. Since we’re not expecting severe thunderstorms in the Central United States anytime soon, this streak is all but certain to set a record.
To form, tornadoes need warm, humid weather and deep troughs in the jet stream, and that has been lacking across the Plains so far in 2018. This year, we’ve seen cold front after front after front punt moisture deep into the tropics. These cold fronts have been driven south by unseasonably chilly air that generally dominates our part of the Northern Hemisphere throughout late winter and into early spring. You can see this by looking at the maps below.
As we close April, it remains oddly quiet across the Central United States.
Oklahoma City based meteorologist Quincy Vagell recently pointed out that though other recent years started quiet as well, they tended to ramp up by now. A difference here, he wrote, “is that the final week of the month very often ends up with a noteworthy outbreak, or at least an extended period of busy tornado activity.”
Across the United States, about 225 tornadoes have formed so far this year, which is about 100 less than an average year.
The tornado drought in the Southern Plains is mostly to blame for the low tally. Only Texas has had tornadoes this year within that zone, and there have been 14. With an average closer to four dozen to this point, things are not bigger in Texas right now.
Going north, the lack of tornadoes is even more pronounced with Oklahoma’s impending record. Kansas still has awhile to go until it hits the record-latest — May 28 — and that has occurred only three times since 1950, according to the National Weather Service.
In places where moisture is generally plentiful, a different story has emerged.
Look at Louisiana. About four dozen tornadoes have touched down there on 11 days this year. This has already surpassed its annual average of about three dozen. Mention a tornado drought to residents of the Bayou State, and you may get a funny look or two. The story is similar in the surrounding region of the mid-South, in particular. Arkansas, Louisiana, Mississippi and Alabama are all running at least a little above-average season to date. But even here, giant tornadoes thankfully been at a minimum.
Elsewhere, the story is generally a somewhat below-average one in the Southeast and a well-below-average one in places to the north overall, although there are a few spots of higher activity.
Tornadoes are notoriously fickle when it comes to trends. History is full of examples where people let their guards down only to be bombarded later in the season.
A season like 2004 is a prime example of tornado season going from zero to 60 overnight. Through April 25 that year, there were even fewer tornadoes than 2018 — only about 180. The season went on to finish in the top spot with 1,817 tornadoes. While it was heavily aided by an active Gulf hurricane season, it also had an active back half of spring after a quiet beginning.
More recently in 2013, tornado numbers were almost exactly on par with 2018. The season overall was quieter than average, but it also featured a couple of historic storms — including the EF-5 in Moore, Okla., that killed 24, and the El Reno, Okla., EF-3 tornado, which killed eight people, including three notable storm chasers.