If it moves, tie it down.
That’s one takeaway from an early-season forecast that predicts an above-average 2013 Atlantic Basin hurricane season. The hurricane watchers base their forecast on warming of the tropical Atlantic and an expected lack of an El Niño event.
The forecast calls for 18 named storms during the hurricane season, which falls between June 1 and Nov. 30. Nine of those are expected to become hurricanes and four will be major hurricanes (Saffir/Simpson category 3-4-5) with sustained winds of 111 mph or greater.
“The tropical Atlantic has anomalously warmed over the past several months, and it appears that the chances of an El Niño event this summer and fall are unlikely,” says Phil Klotzbach, who authors the forecast with William Gray of the Colorado State University Tropical Meteorology Project. “Typically, El Niño is associated with stronger vertical shear across the tropical Atlantic, creating conditions less conducive for storm formation.”
The team’s annual predictions are intended to provide a best estimate of activity to be experienced during the upcoming season, not an exact measure.
The forecasts are based on the premise that global oceanic and atmospheric conditions – such as El Niño, Atlantic Basin sea-surface temperatures and sea-level pressures – that preceded active or inactive hurricane seasons in the past provide meaningful information about similar conditions that will likely occur in the current year.
“All vulnerable coastal residents should make the same hurricane preparations every year, regardless of how active or inactive the seasonal forecast is,” Klotzbach says. “It takes only one landfall event near you to make this an active season.”
Five hurricane seasons since 1900 exhibited oceanic and atmospheric characteristics most similar to those observed in February-March 2013: 1915, 1952, 1966, 1996 and 2004. Four of the five years had above-average hurricane activity.
The team predicts that tropical cyclone activity in 2013 will be about 175% of the average season. By comparison, 2012 witnessed tropical cyclone activity that was 131% of the average season.
The hurricane forecast team's probabilities for a major hurricane making landfall on U.S. soil in 2013 are:
- Entire U.S. coastline – 72% (average for last century is 52%)
- U.S. East Coast including Florida peninsula – 48% (average for last century is 31%)
- Gulf Coast from the Florida Panhandle westward to Brownsville, TX – 47% (average for last century is 30%)
- Caribbean – 61% (average for last century is 42%)
Probabilities of tropical storm-force, hurricane-force and major hurricane-force winds occurring at specific locations along the U.S. East and Gulf Coasts are listed on the forecast team's landfall probability website at www.e-transit.org/hurricane. The site provides U.S. landfall probabilities for all coastal states as well as 11 regions and 205 individual counties along the U.S. coastline from Brownsville, TX, to Eastport, ME.
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