Scatter plot of minimum pressure and maximum azimuthal wind forAtlantic and Eastern Pacific tropical cyclones (1989-2004 + Hurricane Isaac 2012 [red]). Figure adapted from: Knaff & Zehr, 2007, Weather Forecasting, 22, 71-88.

Global storm count: ~90 per year

Locations of tropical cyclone genesis in January

Locations of tropical cyclone genesis in February

Locations of tropical cyclone genesis in March

Locations of tropical cyclone genesis in April

Locations of tropical cyclone genesis in May

Locations of tropical cyclone genesis in June

Locations of tropical cyclone genesis in July

Locations of tropical cyclone genesis in August

Locations of tropical cyclone genesis in September

Locations of tropical cyclone genesis in October

Locations of tropical cyclone genesis in November

Locations of tropical cyclone genesis in December

Locations of tropical cyclone genesis

Seasonal cycle of tropical cyclogenesis

Northern Hemisphere solidSouthern Hemisphere dashed

Hawkins, H. F., and D. T. Rubsam, 1968: “Hurricane Hilda, 1964. Part II: Structure and budgets of the hurricane on October 1, 1964. Monthly Weather Review, 96, 617-636.

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 20150

5

10

15

20

25

30

35

40

45

50

AtlanticE. PacificW. Pacific

Number of storms (1970-2011) by basin

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 20150

10

20

30

40

50

60

70

80

90

APNH

Number of storms (1970-2011) in Northern Hemisphere (red)And Atlantic and North Pacific only (blue)

1940 1950 1960 1970 1980 1990 2000 2010 20200

100000000000

200000000000

300000000000

400000000000

500000000000

600000000000

26.8

27

27.2

27.4

27.6

27.8

28

28.2

28.4

28.6

PDISST

Atlantic Main Development Region SST (ASO mean) and power dissipation (whole season, whole basin)1-3-4-3-1 filter applied to smooth interannual variability