WEATHER LESSONS - Fujita Tornado Scale
Biography of Dr. Tetsuya "Theodore" Fujita
Dr. Tetsuya "Theodore" Fujita (1920-1998)
Dr. Fujita began studying meteorology in 1947 in Japan after he heard approaching thunder. He began to record the direction of the cloud to ground lightening and the time between the lightening and the thunder. From this, he deduced that there were three separate sub centers of storm activity. He then began mapping fronts, showing extreme detail using exact times, dates, and distances. Dr. Fujita began inventing some new ideas about how thunderstorms work and began a correspondence with the American meteorologist Horace Byers. Dr. Fujita, Dr. Byers, and Roscoe Braham Jr. started the Thunderstorm Project to find the structure of storms. They discovered that each thunderstorm cell had a strong updraft and a rain-flushed downdraft. During this time he also invented the idea of mesoscale systems
In Dr. Fujita's research of tornadoes, he came up with the concept of tornado families. It was previously thought that tornado damage to an area was caused by a single tornado. He also introduced the terms "wall cloud" and "tail cloud" which are used commonly today in tornado discussions.
In the 1970's, Dr. Fujita invented the Fujita Scale to measure the link between tornado damage and wind speed. The highlight of Dr. Fujita's outbreak analysis occurred with the tornado outbreak of 1974. By now, Dr. Fujita was an avid weather analyzer. He would study tornadoes and their destruction, such as the 1965 Palm Sunday outbreak, to analyze their formation, paths, and destruction. After the 1974 outbreak, he mapped most of the April 3 and 4 tornadoes using Fujita Scale-intensity contours (see below). From his analysis, he determined that tornadoes occur primarily in the warm sector of a surface cyclone. Associated with the study of this outbreak, he discovered the concepts of microbursts and downbursts. This was a key element in distinguishing between tornado and non-tornado damage.
Fujita-Pearson Tornado Scale (FPP scale)
|F1||Tornado, Fujita Scale 1|
|Winds: 73-112 mph||Effects: Roofs damaged; barns torn apart; weak trailers flipped and torn apart; cars thrown from roads; sheet metal buildings destroyed.|
|Categories of Fujita Scale 1|
|S1||Category I Hurricane, Minimal|
|Winds: 74-95 mph Barometer: >= 980 mb (hPa), 28.94 inches Storm surge: 4-5 ft|
|Effects: Damage primarily to shrubbery, trees, foliage, unanchored mobile homes, and small unsecured coverings (i.e. carports). No significant damage to well anchored structures. Some damage to poorly constructed signs. Low lying coastal roads inundated. Minor pier and marina damage. Small craft exposed to open moorings may be torn free.|
|S2||Category II Hurricane, Moderate|
|Winds: 96-110 mph Barometer: 979-965 mb (hPa), 28.91-28.50 inches Storm surge: 6-8 ft|
Considerable damage to foliage and shrubbery, smaller trees uprooted. Major damage to exposed mobile homes. Extensive damage to poorly constructed
signs. Possible damage to roofing, windows and doors. No major damage to secure buildings. Coastal roads and low-lying escape routes cut by rising waters
2 to 4 hours prior to storm arrival. Considerable damage to piers. Marinas flooded by storm surge. Small craft in open moorings ripped free from mooring.
Evacuation of low-lying areas and shoreline residences required.
Alma: 06/08/66, 110 mph, 970 mb.
|S3||Category III Hurricane, Extensive|
|Winds: 111-130 mph Barometer: 964-945 mb (hPa), 28.47-27.91 inches Storm surge: 9-12 ft|
Foliage torn from trees; large trees blown down. Practically all poorly constructed signs destroyed. Some damage to roofing and windows that are
unbraced. Mobile homes unsecured destroyed. Serious flooding of coastal areas and smaller buildings destroyed along shoreline; larger structures near
coast damaged by battering waves and debris. Low-lying escape routes cut by rising water inland 3 to 5 hours before hurricane center arrival. Terrain
continuously lower than 5 ft above mean sea level may flood as much as 8 miles or more inland. Evacuation of shoreline and low-lying surrounding area
where hurricane is estimated to come ashore may be required to be evacuated.
Bob: 08/19/91, 115 mph, 953 mb.
|F2||Tornado, Fujita Scale 2|
|Winds: 113-157 mph||Effects: Strongly built schools, homes, and businesses unroofed; concrete block buildings, weak homes, and schools destroyed; trailers disintegrated.|
|Categories of Fujita Scale 2|
|S4||Category IV Hurricane, Extreme|
|Winds: 131-155 mph Barometer: 944-920 mb (hPa), 27.88-27.17 inches Storm surge: 13-18 ft|
Shrubs and trees uprooted; all signs blown down or destroyed. Extensive damage to roofing, windows, and doors. Complete failure of roofs on
smaller structures. Complete destruction of mobile homes whether secured or not. Terrain continuously lower than 10 feet above mean sea level may
flood requiring massive evacuation of residences as far as 6 miles or more inland. Major damage to lower floors of large structures near shore line
due to flooding and debris. Low-lying escape routes will be cut off 3 to 5 hours prior to hurricane center arrival due to flooding from storm surge.
Major erosion of beachheads and coastal formations.
David: 06/08/66, 08/30/79, 150 mph, 924 mb.
Hugo: 09/15/89, 140 mph, 918 mb.
Andrew: 08/23/92, 150 mph, 922 mb.
|S5||Category V Hurricane, Catastrophic|
|Winds: >155 mph Barometer: barometer < 920 mb (hPa), 27.17 inches Storm surge: >18 ft|
Shrubs and trees blown down and uprooted; considerable damage to roofs of all buildings; all signs down. Very severe and extensive damage to
windows and doors. Complete failure of roofs on several residences and industrial buildings. Extensive shattering of glass from pressure variation
and blown debris. Some complete building failures. Smaller buildings are overturned or destroyed. Complete destruction of mobile homes. Major damage
to lower floors of large structures less than 15 ft above sea level within 750 yards of shore. Low-lying escape routes cut off due to flooding 6 to 8
hours prior to hurricane center arrival. Massive evacuation of residential areas on low-lying ground within 5 to 10 miles of shore may be required with
possible extension up to 15 miles inland.
Camille: 08/18/69, 165 mph, 909 mb.
Gilbert: 09/14/88, 160 mph, 888 mb.
|F3||Tornado, Fujita Scale 3|
|Winds: 158-206 mph||Effects: Strongly built schools, homes, and businesses have outside walls blown away; weaker homes completely swept away.|
|F4||Tornado, Fujita Scale 4|
|Winds: 207-260 mph||Effects: Strongly built homes have all interior and exterior walls blown apart; cars thrown 300 yards or more in the air.|
|F5||Tornado, Fujita Scale 5 ("the finger of God")|
|Winds: 261-318 mph||Effects: Strongly built homes are completely blown away.|
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