A very active Atlantic hurricane season is underway, and with morestorms projected, NOAA today increased the number of storms in its 2005hurricane season outlook. NOAA expects an additional 11 to 14 tropicalstorms from August through November, with seven to nine becominghurricanes, including three to five major hurricanes. In total, thisseason is likely to yield 18 to 21 tropical storms, with nine to 11becoming hurricanes, including five to seven major hurricanes.
"The tropics are only going to get busier as we enter the peak ofthe season," said Brig. Gen. David L. Johnson, USAF (Ret.), director ofthe NOAA National Weather Service. "This may well be one of the mostactive Atlantic hurricane seasons on record, and will be the ninthabove-normal Atlantic hurricane season in the last eleven years."
"Although we have already seen a record-setting seven tropicalstorms during June and July, much of the season's activity is still tocome," said Gerry Bell, lead meteorologist on NOAA's Atlantic HurricaneSeasonal Outlook. The predicted high levels of activity during theremainder of the season are consistent with NOAA's pre-season outlookissued last spring, and are comparable to those seen during August toOctober of the very active 2003 and 2004 seasons.
Atmospheric and oceanic conditions that favor an active hurricaneseason are now in place, as was predicted in the pre-season outlook."Warmer-than-normal sea-surface temperatures and low wind shear areamong the culprits behind these stronger and more numerous storms,"Bell added.
This confluence of optimal ocean and atmosphere conditions has beenknown to produce increased tropical storm activity in multi-decadal(approximately 20-30 year) cycles. Because of this, NOAA expects acontinuation of above-normal seasons for another decade or perhapslonger. NOAA's research shows that this reoccurring cycle is thedominant climate factor that controls Atlantic hurricane activity. Anypotentially weak signal associated with longer-term climate changeappears to be a minor factor.
The multi-decadal signal that has contributed to increased Atlanticactivity since 1995 has also produced a marked decrease in hurricanesin the eastern Pacific hurricane region. Similar conditions alsoproduced very active Atlantic hurricane seasons during the 1950s and1960s. In contrast, the opposite phase of this signal during 1970-1994resulted in only three above-normal Atlantic hurricane seasons in theentire 25-year period.
Conditions that steer hurricanes toward land are well known, but aredifficult to predict on seasonal time scales and are often related todaily weather patterns. However, historical records indicate that anaverage of two to three additional hurricanes could strike the U.S.between August and November.
"Knowing precisely where a hurricane will strike and at whatintensity cannot be determined even a few days in advance," said MaxMayfield, director of the NOAA National Hurricane Center. Mayfieldadds, "Residents and government agencies of coastal and near-coastalregions should embrace hurricane preparedness efforts and should beready well before a tropical storm or hurricane watch is posted."
An average Atlantic hurricane season, which runs from June 1 throughNovember 30, produces 10 named storms in which six become hurricanes,including two major hurricanes with winds of at least 111 mph. The mostactive hurricane season was in 1933 with 21 storms, followed by 1995with 19 storms. The most hurricanes in a season was 12 in 1969, and thehighest number of major hurricanes was eight in 1950.
The 2005 Atlantic hurricane outlook is a joint product of scientistsat NOAA's Climate Prediction Center, Hurricane Research Division andNational Hurricane Center. NOAA meteorologists use a suite ofsophisticated numerical models and high-tech tools to forecast tropicalstorms and hurricanes. Scientists rely on information gathered by NOAAand the U.S. Air Force Reserve personnel who fly directly into stormsin hurricane hunter aircraft; NOAA, NASA and the U.S. Department ofDefense satellites; NOAA data buoys, weather radars and partners amongthe international meteorological services.
NOAA, an agency of the U.S. Department of Commerce, is dedicated toenhancing economic security and national safety through the predictionand research of weather and climate-related events and providingenvironmental stewardship of the nation's coastal and marine resources.
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