Salomon Smith Barney meteorologist Jon Davis released his 2002 hurricane forecast last week calling for normal to below normal hurricane activity this year based mainly on the growing likelihood of an El Nino weather pattern in the equatorial Pacific. It is well known that in El Nino years Atlantic hurricane activity is hindered by a strong southern jet stream, Davis said. Pacific sea surface temperatures currently are warmer than normal but not quite enough yet to call an El Nino.

Davis said in El Nino years, the southern jet stream typically “shears off” or breaks apart Atlantic tropical systems before they can get organized. “If the warming that has been occurring since late January continues, we should be in a weak El Nino event by the end of the summer or early fall — August or September,” said Davis. “We continue to feel that the upcoming El Nino event will be a weak to moderate event with no indication of a strong event such as the ultra-intense 97-98 episode. The fact that much of the 2002 hurricane season will be close to or in El Nino conditions put odds in favor of an inactive season.”

Davis also noted that Atlantic sea surface temperatures are unusually cool this year, providing less fuel (heat) for tropical systems to develop. However, Atlantic sea surface temperatures can change faster than Pacific temperatures so by the peak of the hurricane season, the situation could be different, he said. At least for the early part of the season, the cool Atlantic should provide a negative influence on tropical activity.

Davis predicts that tropical storm and hurricane numbers this year will fall below the 50-year average of 11 and six, respectively. Although this means there is less of a chance that gas production will be impacted by tropical activity this year, there is one strange peculiarity about hurricanes making landfall during inactive seasons, or seasons with below normal tropical storm and hurricane formation. In fact, in inactive hurricane years, there’s actually a slightly greater chance of a hurricane making landfall on the U.S. coast, including the Gulf of Mexico.

Only two-thirds of all Atlantic storms ever reach the Gulf, but during inactive hurricane years 37% of storms make landfall compared to 30% during active years. About 14% of all storms in inactive years reach the Gulf compared to only 11% in active years.

“During inactive years, there is a slightly higher bias of an individual storm hitting the United States as well as impacting energy operations in the northern Gulf,” said Davis. “In active years, odds are slightly lower… Obviously from a seasonal basis, the threat is greater during active seasons since there are simply more storms than in inactive years. This overrides the percentage difference between 11 to 14%.”

“Thus there are less storms to monitor during inactive years, but they have to be watched a bit closer since the odds are slightly higher of an impact to the United States and energy operations in the northern Gulf of Mexico.”

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