With the 2005 Atlantic hurricane season less than halfway over, the National Oceanic and Atmospheric Administration (NOAA) said last raised its activity prediction, warning that up to 14 more tropical storms and five more major hurricanes could still be out there.
After studying recent weather patterns, the agency said it now expects a seasonal total of 18-21 tropical storms (mean is 10), with nine to 11 becoming hurricanes (mean is six), and five to seven of these becoming major hurricanes (mean is two to three).
The upward revision is significant when compared to NOAA's earlier prediction. In May, the agency predicted the 2005 season would be above normal, with up to 15 tropical storms and nine hurricanes (see NGI, May 23).
The Atlantic hurricane season typically peaks in August and ends on Nov. 30. The new activity projection could threaten the previous record of tropical storms, which was 19 storms, set in 1995.
NOAA puts the chances of an above-normal 2005 Atlantic hurricane season at 95% to 100%, according to a consensus of scientists, the Climate Prediction Center, the Hurricane Research Division and the National Hurricane Center (NHC). This forecast reflects NOAA's highest confidence of an above-normal hurricane season since its outlooks began in August 1998.
With seven tropical storms and two major hurricanes already passed this year, NOAA said the remainder of the season should see an additional 11-14 tropical storms, with seven to nine becoming hurricanes and three to five of these becoming major hurricanes.
"These very high levels of activity are comparable to those seen during August-November 2003 and 2004," NOAA said in its update. "Given the forecast that the remainder of the season will be very active, it is imperative that residents and government officials in hurricane-vulnerable communities have a hurricane preparedness plan in place."
The agency pointed out that the near 100% chance of an above-normal season is higher than the 70% likelihood indicated in NOAA's pre-season outlook issued May 16. "This increased certainty reflects the fact that the atmospheric and oceanic conditions favoring hurricane formation that were predicted in May are now in place," NOAA said. "These conditions, combined with the high levels of activity already seen, make an above-normal season nearly certain."
Hurricane seasons during 1995-2004 have averaged 13.6 tropical storms and 7.8 hurricanes, with 3.8 being major hurricanes. NOAA classifies all but two of these 10 seasons (El Nino years of 1997 and 2002) as above normal, and six of these years as hyperactive. If the 2005 season is as predicted, it will be the seventh hyperactive season in the last 11 years.
In contrast, NOAA said that during the preceding 1970-1994 period, hurricane seasons averaged nine tropical storms, five hurricanes and 1.5 major hurricanes. NOAA classifies 12 of these 25 seasons as being below normal, only three as being above normal and none as being hyperactive.
While 2005 has been predicted as a hyperactive season, NOAA admits that the main uncertainty in this outlook is the number of landfalling tropical storms and hurricanes in the United States and the region around the Caribbean Sea.
"Although the conditions that produce hurricane landfalls are well known, they are very difficult to predict at these extended ranges because they are often related to the daily weather patterns rather than the seasonal climate patterns," NOAA said. "It is currently not possible to confidently predict the number or intensity of landfalling hurricanes at these extended ranges, or whether a given locality will be impacted by a hurricane this season."
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