NEW YORK Sep 1, 2006 (Dow Jones Newswires)
Declaring their month-earlier report "a bust," widely watched forecasters at Colorado State University on Friday said they expect the overall 2006 Atlantic hurricane season to be "slightly below" average, instead of more active than normal.
Projections were upended by unexpected high concentrations of dry West African dust which sapped moisture from the atmosphere, eliminating a critical component of storm formation, forecasters said.
Instead of four named storms, three hurricanes and one intense hurricane, August featured just a fairly meek Hurricane Ernesto.
While forecasters lowered their expectations for the remainder of the season, which runs through Nov. 30, activity in September - when about half of all severe storm activity occurs - will be "slightly above average," they said.
Overall, for the season, 13 named storms are expected, down from 15 earlier, of which five will become hurricanes, down from seven in a month-earlier forecast. Two intense hurricanes, packing winds of 111 miles per hour or greater (category 3-4-5) are now expected, down from three in the month-ago forecast.
The long-term average is 9.6 named storms, 5.9 hurricanes and 2.3 intense hurricanes.
Citing "changing climate signals and below-average activity in the first third of the season," forecasters now expect the full season - from June 1 to Nov 30 - to be "slightly below average...with far less activity than was experienced in each of the last two years."
September May Be More Active
Pre-season, the forecasters called for a more active than normal season, but below the record-breaking 2005 year, which featured deadly Hurricanes Katrina and Rita, which battered the U.S. Gulf Coast and did substantial damage to oil and gas production facilities and refineries, pushing gasoline prices to record highs a year ago. Storm disruption sent crude oil prices soaring to $70 a barrel a year ago for the first time and pushed retail gasoline prices to record-highs topping $3 a gallon.
At one point, about 28% of U.S. refining capacity was shut down as result of the storms. Total regional crude oil output of 1.5 million barrels a day under federal leases was shut in, along with 80%, or 8 billion cubic feet per day, of the area's natural gas production.
The outlook for September calls for "slightly above-average" activity, with five named storms, three hurricanes and two major hurricanes. There is a greater than normal chance of storms making landfall in the month, too.
The probability of a named storm making landfall in the U.S. in September is 74%, compared with 67% over the past 52 years. The chance of a hurricane hitting in September is 59%, compared with the average of 48%, while the possibility of an intense hurricane making landfall in the month is 35%, up from 27%.
For October, the forecasters see "below average" activity, with two named storms, three hurricanes and no major hurricanes. Landfall probabilities in October are below average.
In October, the forecasters see a 22% of a tropical storm making landfall, compared with 29% historically. The change of hurricane landfall is 14%, compared with 15% on average, and the potential for landfall by an intense hurricane is 4%, down from 6%.
In a statement, forecasters Philip Klotzbach and William Gray said the changing conditions behind the revised forecast include "drier tropical Atlantic mid-level moisture fields, high levels of West African dust over the Atlantic, and a warmer eastern equatorial Pacific indicating a potential El Nino event this fall."
El Nino refers to the occurrence of unusually warm water in the Pacific Ocean that can have important global consequences, including sometimes increased rainfall in the southern tier of the U.S. and Peru, which has caused destructive flooding and droughts in the western Pacific, according to the National Oceanic and Atmospheric Administration (NOAA).
An Eye On El Nino
In early August, NOAA forecasters said there was a 50% chance of weak El Nino conditions developing in late 2006 through early 2007.
The Colorado forecasters said storm activity was "average" in June and July, while Hurricane Ernesto lasted just one day in August, compared with an average of six hurricane days in the month. Oil and gas producers in the U.S. Gulf evacuated some staff from offshore facilities as a precaution and energy markets were on edge before the storm died out quickly.
The 2005 season was the busiest ever, with 28 named storms, 15 hurricanes and seven intense hurricanes. Last month NOAA cut its 2006 seasonal forecast, expecting a still above-normal season, with 12-15 named storms, seven to nine hurricanes and three to four intense hurricanes.
In the past two years, 13 major hurricanes formed in the Atlantic basin, with seven striking the U.S. coast. In the prior eight years, just three of 32 major hurricanes crossed the coast.
"We recommend that there not be too much read into the last two hurricane seasons of 2004-2005," Gray said. "The activity of these two years was unusual, but well within natural bounds of hurricane variation. This is how nature sometimes works."
Klotzbach, noting that the forecasters had accurately predicted the August activity trend in the previous five years, noted that just a single storm making landfall can be devastating, regardless of how busy the season is. "In 1992, the season wasn't very active, but we had Hurricane Andrew come into South Florida as a category five," he said.
Copyright (c) 2006 Dow Jones & Company, Inc.
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