Thursday, August 2, 2007

TS Chantal (2007) In Historical Perspective

I decided to look at the other storms in the storm record that had a similar genesis point to tropical storm Chantal since 1930. It proves very interesting as it further reinforces the idea that serious undercounting of North Atlantic tropical storm in the pre-satellite era is endemic. I decided to look at all storms that had their genesis in the box bordered by the lines, 40 degrees north, 30 degrees north, 60 degrees west, and 70 degrees west (roughly this box brackets the island of Bermuda.) I've broken it down by decade below:


1938, Tropical Storm #6, 40kts


1942, Hurricane #3, 94kts
1942, Tropical Storm #5, 45kts
1942, Tropical Storm #6, 45kts
1943, Tropical Storm #7, 50kts


1957, Hurricane Frieda, 70kts


1964, Tropical Storm, 45kts


1971, Hurricane #2, 70kts
1972, Hurricane Betty, 90kts
1973, Hurricane Fran, 70kts
1974, Subtropical #3, 45kts
1976, Hurricane Candice, 80kts


1981, Tropical Storm Bret, 60kts
1981, Tropical Storm Condy, 50kts
1983, Hurricane Chantal, 65kts
1984, Subtropical #1, 50kts
1984 Tropical Storm Cesar, 50 kts


1997, Hurricane Bill, 65kts
1998, Hurricane Karl, 90kts


2001, Hurricane Karen, 70kts
2003, Tropical Storm Ana, 45kts
2004, Tropical Storm Nicole, 45kts
2007, Tropical Storm Chantal, 45kts

Average number of storms per year in each decade:

Pre-satellite era

1930's: 0.1
1940's: 0.4
1950's: 0.1
1960's: 0.1

Satellite era:

1970's: 0.5
1980's: 0.6
1990's: 0.2
2000's: 0.5

For entire pre-satellite era 1930-1969: 0.175
For entire satellite era 1970-2007: 0.447

It should also be noted that four of the seven total storms found in the pre-satellite era were found at a time when the U.S. military had a submarine and air presence at Bermuda engaged in active wartime patrolling during the Second World War.

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