After the devastating EF-5 Oklahoman tornado tore through the town of Moore, many are wondering what exactly allowed for a storm of this nature to develop. Just a day before, the Oklahoma City area was targeted with numerous tornado touch downs.
The peak estimated wind speeds were 200-210 mph. The width of the twister was 1.3 miles and for this reason, it was referred to as a “wedge tornado.” The path of destruction is approximated to be a long & deadly 17 miles.
It is important to understand that tornadoes of this sort, EF-4 & EF-5, are very rare. Their occurrence in the Northwest is nearly non-existent. Twisters can form anywhere, any time of year. However, the mountainous terrain of Southwest Oregon are not favorable conditions for tornado development.
There are many factors that came into play this past Monday across the Central Plains. First, the primary ingredients for any type of thunderstorm growth is a lifting mechanism, moisture, and instability. All three were in full force and not only one but two lifting mechanisms were present- a cold front and dry line.
The clashing of warm and cold air along the cold front, acts as a lift to rise surface air. The dry line separates a gradient of very dry vs. moist air. The moisture coming up from the Gulf of Mexico is one of the main drivers of severe weather across the Central Plains. Because there land is so flat, the moisture is not blocked by any terrain and freely moves north when the winds are out of the south, southeast.
In addition to this, the strong daytime heating of the sun, allowed for lots of rising air. This is known as instability. The placement of the jet stream was an important factor as well. There was a jet streak present, an area of winds in excess of 100mph, very high in the atmosphere. These enhanced high level winds also enhanced the wind shear. Wind shear refers to the changing of wind speed & direction with height. Not only did we have winds from the Southeast, but also the South, the Northwest, and the West from the jet stream.
It is not often that all of these factors will come together at the same time. It was a matter of bad luck, and coincidence that Moore, Ok. has experienced now two times, the horrifying and terrible reality of nature’s deadliest force.