Good morning all! I’ve got another article review for ya as you look to enter your lunch break; take a quick read, and have a great rest of the day!
This article, ‘‘Bookend Vortex’’ Induced Tornadoes along the Natchez Trace by Russell L. Pfost and Alan E. Gerard looks a little closer to home and gives us a closer look at the development of tornadoes and the destructive one that moved across Mississippi on May 8th 1995
Summary:
The tornado was initiated as a “comma head echo” in Claiborne County, MS and the path of the tornado followed along the path of the Natchez Trace highway which led to mild destruction of trees along the way before fading, a second path arose and moved along the opposite side of the first route and the winds from this track led to further tree and brush destruction but very little impact on homes and cities was found as they were in the middle of a mostly forested area.
The authors included soundings taken from Jackson, MS at 1200 UTC on the day of the hurricane as well as the sounding from Lake Charles, LA at the same time and both show a large inversion as well as unstable warm pockets of air from 400mb to 850mb.
As they move through the article, they provide the synoptic conditions around this event. They state that a low-level jet was residing over south Mississippi and that there was ample difluence in the valley that when everything aligned, created a pattern resembling the bow echo that they illustrated prior in the article. They show that there was a very strong cap with a high potential energy for convective movement. Furthermore, we see radar evidence of strong reflectivity out of Lake Charles and a strong rotation as found from color reflectivity maps provided in the article.
Eyewitness accounts say that the true beginning of the tornado genesis was at approximately 1941 UTC and that from 1941 to 2002 UTC the core held 6 km width and the rear inflow at it’s strongest point was 39.5 m s^-1. When the authors address their solution for warning guideline adaption should find bow echo favoring environments as a large priority and letting each area have their own approach to tornado identification criteria. Tornado genesis in the south differs from that in the plains and thus, each should have their own parameters for tornado warnings.
3 Things for Further Study:
- Why does a tornado occurrence on the southeast side of the comma head, behind the bow line, correlate with an increased rear inflow jet? How do all of the different positions of formation relate to the inflow strengths?
- Why does the hodograph from Lake Charles, LA (while showing a prominent rotation) not give a deeper curl for a tornado of this magnitude? Wouldn’t the hodograph show a more dramatic curl to show a tornado with such a strong core and rotation?
- The comma shaped tornado formation – how does the downburst that’s in the middle creating the bow lead to the cyclonic rotation of the head and is this the formation of the tornado? I would like to look deeper into the formation of a tornado and the shape from above to pinpoint where things occur on a line that drives across an area.
Modern Meteorology:
This article while primarily looking at an event in the past addresses (like so many others) how tornadogenesis varies for each region. However, the strength of each tornado can be identified if we look more critically at the core, elevation, and rotation strength as well as other factors in the area. (trees, water, buildings, etc.) I think this gives a real account of when scientist needed to look at their independent values and make a judgement call based on their local region and how the atmosphere reacts in certain conditions as opposed to following guidelines that are expected to cover anywhere from the plains to the east coast.
If you want to read the article, you can find it here: https://journals.ametsoc.org/
Thanks for reading! Have a great evening!
