With a very active Atlantic hurricane season underway, the government’s hurricane experts are warning that the bulk of this season’s storms are still to come.
The National Oceanic & Atmospheric Administration said it expects an additional 11 to 14 tropical storms from August through November, with seven to nine becoming hurricanes, including three to five major hurricanes. In total, this season is likely to yield 18 to 21 tropical storms, with nine to 11 becoming hurricanes, including five to seven major hurricanes.
“The tropics are only going to get busier as we enter the peak of the season,” said Brig. Gen. David L. Johnson, USAF (Ret.), director of the NOAA National Weather Service. “This may well be one of the most active Atlantic hurricane seasons on record, and will be the ninth above-normal Atlantic hurricane season in the last eleven years.”
“Although we have already seen a record-setting seven tropical storms during June and July, much of the season’s activity is still to come,” said Gerry Bell, lead meteorologist on NOAA’s Atlantic Hurricane Seasonal Outlook. The predicted high levels of activity during the remainder of the season are consistent with NOAA’s pre-season outlook issued last spring, and are comparable to those seen during August to October of the very active 2003 and 2004 seasons.
Atmospheric and oceanic conditions that favor an active hurricane season are now in place, as was predicted in the pre-season outlook. “Warmer-than-normal sea-surface temperatures and low wind shear are among the culprits behind these stronger and more numerous storms,” Bell added.
This confluence of optimal ocean and atmosphere conditions has been known to produce increased tropical storm activity in multi-decadal (approximately 20-30 year) cycles. Because of this, NOAA expects a continuation of above-normal seasons for another decade or perhaps longer. NOAA’s research shows that this reoccurring cycle is the dominant climate factor that controls Atlantic hurricane activity. Any potentially weak signal associated with longer-term climate change appears to be a minor factor.
The multi-decadal signal that has contributed to increased Atlantic activity since 1995 has also produced a marked decrease in hurricanes in the eastern Pacific hurricane region. Similar conditions also produced very active Atlantic hurricane seasons during the 1950s and 1960s. In contrast, the opposite phase of this signal during 1970-1994 resulted in only three above-normal Atlantic hurricane seasons in the entire 25-year period.
Conditions that steer hurricanes toward land are well known, but are difficult to predict on seasonal time scales and are often related to daily weather patterns. However, historical records indicate that an average of two to three additional hurricanes could strike the U.S. between August and November.
“Knowing precisely where a hurricane will strike and at what intensity cannot be determined even a few days in advance,” said Max Mayfield, director of the NOAA National Hurricane Center. Mayfield adds, “Residents and government agencies of coastal and near-coastal regions should embrace hurricane preparedness efforts and should be ready well before a tropical storm or hurricane watch is posted.”
An average Atlantic hurricane season, which runs from June 1 through November 30, produces 10 named storms in which six become hurricanes, including two major hurricanes with winds of at least 111 mph. The most active hurricane season was in 1933 with 21 storms, followed by 1995 with 19 storms. The most hurricanes in a season was 12 in 1969, and the highest number of major hurricanes was eight in 1950.
The 2005 Atlantic hurricane outlook is a joint product of scientists at NOAA’s Climate Prediction Center, Hurricane Research Division and National Hurricane Center. NOAA meteorologists use a suite of sophisticated numerical models and high-tech tools to forecast tropical storms and hurricanes. Scientists rely on information gathered by NOAA and the U.S. Air Force Reserve personnel who fly directly into storms in hurricane hunter aircraft; NOAA, NASA and the U.S. Department of Defense satellites; NOAA data buoys, weather radars and partners among the international meteorological services. (Click NOAA image for larger view of the vertical wind shear associated with above normal hurricane season. Please credit “NOAA.”)
NOAA, is an agency of the U.S. Department of Commerce.
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