[filler to mark edit to above post]

And now to finish it off and hope that same letter is in the other word as well...

T?

I've got a suspicion you've nailed the first word... 

_ H E / _ E _ O _ _ _ A _ _ O _

Correct: E, A, O, H

I've been binge-reading/watching stuff about tornadoes lately.  During the upcoming holidays I'm thinking of doing a full list of tornadoes that I personally consider to be the scariest for one reason or another.  Anyway, here's a brief list of some of the tornadoes I would be covering on that list.

The Hackleburg, Alabama EF-5
The single deadliest tornado from the April 27, 2011 tornado outbreak.  It was so powerful that it ripped the roof off of an underground storm shelter, tore asphalt from roads, and stripped tiles from the floors of homes it destroyed.  It is one of the most violent tornadoes ever recorded.  The green sky and sheer ugliness of the tornado just make it scarier.  This video was filmed at the Limestone County Correctional Facility.  Fortunately for the people filming, the tornado just narrowly missed their position. 

https://www.youtube.com/watch?v=yOSG-P1EjfU

1991 Andover, Kansas F-5
The video shone here depicts the tornado as it strikes McConnell Air Force Base as an F-3.  The tornado narrowly missed a squadron of B-1 bombers that were parked on the tarmac.  Two of the bombers were reportedly loaded with live nuclear weapons at the time.  The tornado would ultimately intensify into an F-5 and devastate Andover, Kansas. 

https://www.youtube.com/watch?v=5QK0VA_P83A

2022 Andover, Kansas EF-3
Andover is once again struck by a tornado, though this one was far less devastating.  Regardless, it's an intimidating sight just the same.    It was a very photogenic tornado.  Fortunately there were no fatalities associated with this particular tornado. 

https://www.youtube.com/watch?v=hBB_yOXU4QA

The 2007 Greensburg, Kansas EF-5
The first tornado to receive an EF-5 rating.  This massive nocturnal tornado was 1.7 miles wide with windspeeds of just of around 205 mph. The supercell responsible for this tornado would go on to spawn three additional violent tornadoes, including an EF-3 that was 2.2 miles wide.

https://www.youtube.com/watch?v=XoYyeXybTnw

Speaking of nocturnal tornadoes...

The 2021 Mayfield, Kentucky EF-4
This tornado was arguably an EF-5 but that's a discussion for another time.  The Mayfield tornado was an incredibly powerful and violent tornado.  The video shows the tornado around the time it struck Bremen, where it was at near EF-5 intensity, 1.5 miles wide with wind speeds of almost 200 mph!

https://www.youtube.com/watch?v=yTQEg_UEiKk

The 2015 Rochelle-Fairdale EF-4
Another possible EF-5 contender, this tornado has peak windspeeds estimated at 200 mph, just one mph shy of the EF-5 rating!  This terrifying video, filmed oy Clem Schultz, shows the tornado barreling down on his home in Fairdale, Illinois.  The tornado was at EF-3 intensity at the time of filming.  Miraculously, Schults survived the tornado.  Sadly, his wife and a family friend were not so fortunate, being the tornado's only two fatalities. 

https://www.youtube.com/watch?v=s0c27Twu__o

The 2011 Joplin EF-5
This tornado was an absolute monster.  It was the single deadliest tornado since the 1950s and remains the costliest in US history.  This video is particularly harrowing as the tornado goes from a few wisps beneath a rotating wall cloud to a full wedge in a matter of seconds.  The speed at which the tornado developed and intensified is just insane.  It was heavily rainwrapped as it hit Joplin, making it almost invisible.  This led to many people in the storm's path not taking it seriously, which likely contributed to the catastrophic loss of life from this tornado.

https://www.youtube.com/watch?v=ka8z6xYIQY0