According to the National Hurricane Center, more than 50 million people are at risk for being caught in the path of a tropical storm or hurricane this year. On average seven hurricanes every four years strike the United States while two major (category 3 or greater) cross the United States coast every three years. A hurricane is a warm-core low pressure system without any fronts attached. They develop over warm (80˚F+) tropical or subtropical waters. A weak tropical cyclone is termed tropical storm, while a strong tropical cyclone is termed hurricane.
The Atlantic hurricane season runs from June 1st to November 30th. The Eastern Pacific season runs from May 15th to November 30th. On average, the most tropical cyclones occur in September, but the peak season is mid-August to late October.
This season, we have already had a number of tropical cyclones develop – seven in the Eastern Pacific and four in the Atlantic Basin. We are currently keeping an eye on Tropical Storm Christobal which is off the coast of Virginia, and Tropical Storm Dolly in the Gulf of Mexico.
Tropical Storm Dolly is the biggest threat right now as it strengthens and moves towards the coast of Mexico and Texas. Dolly is moving into an area of very warm ocean waters and weak upper level winds. These conditions are good for development, and the storm is expected to strengthen into a hurricane Tuesday afternoon. Sustained winds are currently at 50 kt. It is taking a while for the eye or inner core circulation of the storm to develop. Once it does winds will increase to near 70 kt and precipitation will become more intense. Dolly is expected to make landfall this Wednesday on Northeastern Mexico and Southern Texas.
A large ball of convection still remains with Tropical Storm Cristobal. Sustained winds are at 55 kt and are not expected to increase. A deepening trough over the Northeastern United States will steer the storm away from the Coastline. As it continues to move to the East into cooler waters, the system will weaken within the next few days.
To meet the criteria for hurricanes, tropical cyclone winds must reach 64 kt.
For more information on the Saffir-Simpson Hurricane Scale and these tropical cyclones, head to the NWS National Hurricane Center website at:
http://www.nhc.noaa.gov/index.shtml
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