The spring of 1973 was one of the wildest on record for tornadic thunderstorms across the plains states. Oklahoma and Kansas experienced a high number of tornadoes. At the time I was learning how to chase and get through classes at the same time. Probably too much time was spent in the "map room" soaking up data instead of calculus, but I still managed to accomplish both tasks. Many of the early situations that required considerable pondering would have been an easy target today, but back then there were few chase rules and little documentation of storm structure.
A brief over view of the day: We had a typical warm and humid summer day in Oklahoma with a light to moderate jet stream flow over the region of interest. At midlevels of the atmosphere there was some concern the flow was not sufficient to produce tornadoes, but back then I didn't realize if the storms "turned into the inflow" the vertical shear parameters that generate rotation would be increased. A surface low pressure system formed over west central Oklahoma and moved slowly south during the late afternoon. This movement influenced the storms to drift more southerly increasing the convergence and shear. Numerous tornadoes occurred over southwestern portions of the state near Ft. Cobb, Carnagie, Anadardo and south of Lawton. The south cell near Lawton dropped as many as 5 narrow tube tornadoes that were visible simoultaneously.
The chase crew for the day consisted of OU students Chuck Doswell, Al
Moller, Steve Tegetmeier and Gene Moore. It was quite an exceptional chase and
one to be remembered.
Images and text © copyright Gene Moore unless otherwise indicated.
The first shot depicts two storm cells to our southwest as we progressed west on highway 9. The second images shows our fist glimpse of a distant wall could. This was part of a dramatic storm structure forming to our west. A classic supercell with very pronounced inflow features was captured by Chuck Doswell using his wide angle lens.
These images show the area east of the storm. Two wall clouds were on the western horizon. The intense back lighting from the low sun angle presented photography problems while shooting under the dark cloud base. A spectacular inflow of easterly low level moisture was rapidly streaming into the storm. The second shot shows the horizontal banding feeding into the storm.
The first tornado of the day became visible as we topped a hill. It appears as a large block on the ground. We would stop on the next hill to shoot the tornado.
A large mass of dirt and dust falls away from the funnel revealing a narrower stove pipe shaped tornado. Many tornado "clouds" are made up of dust that increases the apparent size.
A huge mass of airborne dirt obscures the funnel as it move through open fields. We were shooting from an area of hills and trees, but fortunately we were able to find high ground and an unobstructed view. Portions of southwest Oklahoma are not the flat treeless prairie so often pictured as typical open plains.
The tornado has narrowed considerably in this images. Streamers of dust were falling out of the cloud base and wrapping around the funnel. Note the tilt of the precipitation core on the right of the image. It appears to be tilted toward the tornado, not vertical or away from the funnel as in most tornadic situations.
A large pall of dust remained in the circulation around the tornado. From memory, no lightning was seen or thunder was heard during the shooting of these images, although a dark cloud base persisted overhead.
As the precipitation moves closer to the tornado the tilt of the core is still sloped toward the funnel. The tornado was moving from right to left or south in these images. Actually, we discovered it was moving southwest, or away from us. This may explain the unusual slope of the rain core.
The funnel continues to narrow and becomes arched to the south as outflow from the storm bends the tornado. This is part of the process in the life cycle of a tornado. It usually indicates the tornado will end soon.
A dramatic bend to the southwest is seen in this image. Bright brake lights turn on as a car reaches the top of the hill. The occupants no doubt seeing the tornado for the first time.
As the Ft. Cobb tornado turns into a thin rope and gets lost in the dust a new area of rotation starts nearby. A funnel is forming between the two wall clouds.
While photographing the rotating wall clouds a transparent funnel becomes visible further southwest. At first it looks like a thin rain shaft, but the clear core in the center gives it away as a tornado.
The tornado collects dust and becomes more visible. I had to move forward a little to get a better photography position on the new tornado. This shot was at only 1/15 of a second due to the black cloud over head. Resting on a nearby fence post would help the next shot.
One of my favorite storm shots. The tornado, now well formed moves across the Oklahoma prairie. Two extensive rain-free-base updrafts are seen in the image. Note the slope of the precipitation core on the storm producing the tornado. It is also tilted toward the tornado. In many years of chasing these are the only images I have captured this feature.
Further to the south near Anadarko, Oklahoma another tornado was in progress. While proceeding south to the next storm we came upon damage consisting of busted power poles, downed lines and uprooted trees. Later, while inspecting the damage path we watched the large thunderstorm complex near Lawton.
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