A tropical storm is a rotating, organized system of clouds and thunderstorms that originates over tropical or subtropical waters and has a closed low-level circulation. Tropical cyclones rotate counterclockwise in the Northern Hemisphere. They are classified as follows:
Tropical Depression: A tropical storm with maximum sustained winds of 38 mph (33 knots) or less.
Tropical Storm: A tropical cyclone with maximum sustained winds of 39 to 73 mph (34 to 63 knots).
Hurricane: A tropical cyclone with maximum sustained winds of 74 mph (64 knots) or higher. In the North Pacific, hurricanes are called typhoons; similar storms in other parts of the world are called cyclones.
Major Hurricane: A tropical cyclone with maximum sustained winds of 111mph (96 knots) or higher, corresponding to a Category 3, 4, or 5 on the Saffir-Simpson Hurricane Wind Scale.
According to NOAA, Atlantic hurricane seasons since 1995 have been significantly more active, e.g. more hurricanes and more intense hurricanes, than the previous two decades. The past decade has seen increased U.S. hurricane landfalls.
A hurricane draws its energy from warm ocean water. The warmer the water, the more powerful hurricanes will be. There are recent studies that suggest the warming of the oceans in the Atlantic due to increased greenhouse gas emissions will provide more fuel to the development and intensification of hurricanes. This warming also suggests we can expect more intense hurricanes and persistent active hurricane seasons.
The average annual number of category 4 and 5 hurricanes, which together cause nearly half of all hurricane damage, has more than doubled since the early 1970’s and is likely to continue to increase.
Hurricane History in Baltimore:
1954 Hurricane Hazel October 15
1955 Hurricanes Connie and Diane August 12 and 18
1972 Hurricane Agnes June 21-23
1979 Hurricane David September 5-6
1996 Hurricane Fran September 5
1999 Hurricane Floyd September 16-17
2003 Hurricane Isabel September 18
2004 Hurricane Frances September 8
Hurricane Ivan September 17
Hurricane Jeanne September 28
2011 Hurricane Irene August 27-28
Tropical Storm Lee September 6-9