Hurricane Maria's forecast track Source: NOAA |
There have been two
Category 5 hurricanes in the Atlantic Ocean (Irma, Maria) for only the sixth
time in recorded history and first time since 2007 (Dean, Felix). The record for most Category 5 hurricanes
during an Atlantic hurricane season (June 1 – November 30) is 4 (Emily,
Katrina, Rita, Wilma) in 2005. One
Category 5 hurricane is rare enough, but more than one is exceptionally
rare. For example, prior to 2005, the
last time at least two Category 5 hurricanes occurred during the same season
was in 1961 (Carla, Hattie).
It’s interesting to note
that before weather satellites began being used in the 1960s, it was very
difficult to determine if a tropical storm or hurricane existed if it remained
over the open ocean. There could have
been additional seasons with Category 5 hurricanes, but there was no reliable
way to know they were there. Not only
were there no weather satellites during the 1932 and 1933 hurricanes seasons
(when there were also two Category 5 hurricanes) but that was also before they
were named.
Hurricane Irma broke multiple records during its 75 hours as a Category 5 hurricane over four days (September 5 – 9). It had the highest sustained winds (185 mph) of any Atlantic hurricane outside of the Gulf of Mexico or Caribbean Sea. In fact, Irma’s peak winds of 185 mph tie it with Gilbert, Wilma and the unnamed 1935 Florida Keys hurricane as second highest on record behind only Hurricane Allen (190 mph) in 1980. Moreover, Irma’s 75 hours at Category 5 intensity also ranks as the second highest length of time at Category 5 intensity, narrowly behind the 78 hours a November 1932 hurricane in the Caribbean Sea.
At peak intensity, Maria
was slightly more intense than Irma.
Although Maria’s maximum sustained winds were 175 mph, its minimum
central air pressure was 908 millibars (mb).
Scientists consider air pressure to be a more accurate measure of
hurricane intensity than wind speed.
That’s because lag time can exist in between changes in the air pressure
and wind speed of strengthening or weakening hurricanes. On account of pressure, Hurricane Maria ranks
as the tenth strongest hurricane on record in the Atlantic Ocean. Maria’s lowest air pressure (908 mb) was not
only lower than Irma’s (914 mb), but was the lowest observed pressure of any
Atlantic hurricane since Category 5 Dean (905 mb) in 2007.
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