On the heels of El Nino, its opposite La Nina may soon arrive, which could increase hurricane activity in the Atlantic Ocean, according to the National Oceanic and Atmospheric Administration (NOAA). After getting a free pass last year with less activity than expected, Gulf of Mexico oil and natural gas producers in 2007 could be looking at a storm season more on par with the devastating one seen in 2005. In addition, electricity consumers could feel the price pinch if the western drought associated with La Nina episodes reduces hydropower capacity.

In a weekly update, scientists at the NOAA Climate Prediction Center noted that as the 2006-2007 El Nino faded, surface and subsurface ocean temperatures have rapidly decreased. Recently, cooler-than-normal water temperatures have developed at the surface in the east-central equatorial Pacific, indicating a possible transition to La Nina conditions.

The 2006 Atlantic hurricane season produced near-normal activity with a total of nine named storms, including five hurricanes, two of which became major hurricanes of Category 3 strength or higher (see Daily GPI, Dec. 1, 2006). An average Atlantic hurricane season has 11 named storms, with six becoming hurricanes and two becoming major hurricanes. Unlike the three prior seasons, the stronger hurricanes stayed well out at sea during 2006, sparing the Americas and the Caribbean islands from major hurricane damage.

In 2005 there were 27 named storms, 15 hurricanes and seven major hurricanes in the Atlantic. Of the seven major hurricanes, a record four hit the United States. The havoc caused by Hurricanes Katrina, Rita and Wilma sent front-month natural gas futures to a new all-time-high price in December 2005 of $15.780/MMBtu (see Daily GPI, Dec. 14, 2005).

NOAA explained that during the U.S. spring and summer months, La Nina conditions typically do not significantly impact overall inland temperature and precipitation patterns; however, La Nina episodes often do have an effect on Atlantic and Pacific hurricane activity.

"Although other scientific factors affect the frequency of hurricanes, there tends to be a greater-than-normal number of Atlantic hurricanes and fewer-than-normal number of eastern Pacific hurricanes during La Nina events," said Conrad C. Lautenbacher, under secretary of commerce for oceans and atmosphere and NOAA administrator. "During the winter, usual La Nina impacts include drier and warmer-than-average conditions over the southern United States.

"NOAA's ability to detect and monitor the formation, duration and strength of El Nino and La Nina events is enhanced by continuous improvements in satellite and buoy observations in the equatorial Pacific," Lautenbacher added. "These observing systems include the TAO/TRITON moored and Argo drift buoys, as well as NOAA's polar orbiting satellites."

NOAA explained that La Nina conditions occur when ocean surface temperatures in the central and east-central equatorial Pacific become cooler than normal. These changes affect tropical rainfall patterns and atmospheric winds over the Pacific Ocean, which influence the patterns of rainfall and temperatures in many areas worldwide.

"La Nina events sometimes follow on the heels of El Nino conditions," said Vernon Kousky, research meteorologist at the NOAA Climate Prediction Center. "It is a naturally occurring phenomenon that can last up to three years. La Nina episodes tend to develop during March-June, reach peak intensity during December-February, and then weaken during the following March-May."

Another concern associated with La Nina episodes is the potential for serious droughts in the western U.S., which could diminish hydropower capacity and put upward pressure on power prices.

"The last lengthy La Nina event was 1998-2001, which contributed to serious drought conditions in many sections of the western United States," said Douglas Lecomte, a drought specialist at the NOAA Climate Prediction Center.

As for whether or not La Nina will show for sure, the energy industry will have to wait for NOAA's U.S. Spring Outlook on March 15 and its Atlantic Hurricane Season Outlook in May. Both outlooks will reflect the most current La Nina forecast, the government forecasting firm said.

"While the status of El Nino/La Nina is of vital importance to our seasonal forecasts, it is but one measure we use when making actual temperature and precipitation forecasts," said Kousky.

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