Changes Arrive with New Hurricane Season

by Melanie Devine, North Central Texas Council of Governments

Hurricane season, June 1 - November 30, is almost upon us again. Most tropical storms occur during hurricane season, with the most activity concentrated in the months of August through October, but tropical storms can occur at any time. It is therefore best to get a jump start on the changes coming for the 2009 hurricane season.

 PREDICTIONS: Predictions made in December 2008 about 2009 Atlantic tropical storm activity indicated that we would experience another “above average” year for tropical storm and hurricane activity. Average activity is approximately 11 tropical storms and six hurricanes. As cited from “a group of prominent US-based researchers,” including William Gray’s and Phil Klotzbach’s renowned Colorado State University research team, tropical storms were predicted to number 14, with seven developing into hurricanes. Of those seven, three were expected to be major storms with winds exceeding 110 mph.

However, in a revised forecast, the Colorado team predicted only 12 tropical storms in the Atlantic Basin, with six developing into hurricanes and two reaching a major storm category. Reasons given for the revised forecast include cooler Atlantic water temperatures and wind shear expected to be produced by a Pacific El Nino. Of note to Texas emergency managers, Klotzbach was quoted as saying, “despite the possibility of fewer hurricanes, there’s still a better-than-even chance that at least one major hurricane will make landfall somewhere between Texas and Maine.”

SAFFIR-SIMPSON SCALE: Another change of note is the experimental launch of the new Saffir-Simpson Wind Scale. Traditionally the Saffir-Simpson Scale has been based on the type of damage in the U.S. associated with wind intensity, storm surge, flooding, and tornado impacts. However, due to gross variances in damages associated with the scale, including low storm surge during Category 4 storms (e.g. Charley) and devastating surge from Category 2 storms (e.g. Ike), the new Saffir-Simpson Wind Scale will remove storm surge ranges, flooding impacts and central pressure observations from the scale.

Under the new system, storm surge and flooding predictions and central pressure statements will be addressed separately according to individual specifics associated with each storm. Conditions such as depth of near-shore waters, extent of hurricane-force winds, topographic forcing, and the storm’s speed and angle to the coast will all significantly impact storm surge and will be considered outside of the new Saffir-Simpson Wind Scale.

OTHER CHANGES: The National Hurricane Center has released a list of product and service changes to expand and enhance service for the 2009 hurricane season:

• Storm surge will now be expressed in height above ground level,or inundation
• High/medium/low risk of tropical cyclone development thresholds will now be: Low risk: Less than 30 percent; Medium risk: 30-50 percent; High risk: Greater than 50 percent.
• The size of the tropical cyclone forecast cone will be adjusted.
• To obtain information about these and several other changes for hurricane season 2009, go to http://www.nhc.noaa.gov/pdf/nhc_new_2009.pdf

Other sites of interest

2009-2014 Northern Hemisphere Tropical Cyclone Names: http://www.aoml.noaa.gov/hrd/tcfaq/B2.html

Hurricane FAQs: http://www.aoml.noaa.gov/hrd/tcfaq/tcfaqHED.html

Texas Department of Public Safety Hurricane Awareness: http://www.txdps.state.tx.us/dem/pages/weather_aware_hurricane.html

Resources

NOAA, National Hurricane Center: http://www.nhc.noaa.gov/aboutsshs.shtml

Brown, Tom. Reuters, Miami, December 10, 2008. http://www.reuters.com/article/topNews/idUSTRE4B93XM20081210

Dyer, Willie. National Geographic News, April 7, 2009. http://news.nationalgeographic.com/news/2009/04/090407-hurricane-forecast.html

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