The global hurricane season of 2007: was it unusual?
The year 2007 was a fairly normal year for world-wide tropical cyclone activity. The total number of storms world-wide was 84, two less than the average of 86 (Figure 1). The total number of hurricanes was 43, which is six less than the average of 49. Major hurricanes (Category 3 and higher) and extreme hurricanes (Category 4 and higher) were both slightly below average. No records were broken in any ocean basin for number of storms of any particular category, although the South Indian Ocean did tie its record for number of major hurricanes (seven) and the North Indian Ocean tied its record for number of Category 4 and higher storms (two). One of the North Indian storms (Category 5 Cyclone Gonu) was tied for the strongest tropical cyclone ever observed in the North Indian Ocean. Reliable tropical cyclone records for the globe extend back to 1970, the beginning of the satellite era.
Figure 1. Statistics for the global tropical cyclone season of 2007. The three numbers in each box represent the actual number observed in 2007, followed by the averages from the period 1970-2005 (in parentheses), followed by the record (in red).
Only four Category 5 hurricanes were reported globally in 2007: Tropical Cyclone Gonu (160 mph winds), which hit Oman on June 6 as a Category 1 storm; Super Typhoon Sepat (160 mph winds), which hit Taiwan as a Category 4 storm on August 18; Hurricane Felix (165 mph winds), which hit Nicaragua as a Category 5 hurricane on September 4; and Hurricane Dean (175 mph winds, pressure 905 mb), which hit Mexico's Yucatan Peninsula on August 21 at peak intensity. It is remarkable that half of the globe's Category 5 storms in 2007 occurred in the Atlantic basin, which normally has only about 11% of the globe's tropical cyclones. The globe's strongest tropical cyclone was an Atlantic storm (Dean, 175 mph winds), which is also unusual. I'll have a detailed blog summarizing 2007's notable tropical cyclones next week.
Figure 2. Satellite image of 2007's strongest tropical cyclone at maximum intensity: Hurricane Dean. Post analysis of Dean determined that the storm hit the Yucatan with top sustained winds of 150 knots (175 mph), and a central pressure of 905 mb, the third lowest pressure ever recorded in the Atlantic basin for a landfalling storm. Only the 1935 Labor Day Florida Keys storm (892 mb) and Hurricane Gilbert (900 mb) had lower pressures at landfall.