Warmer than normal temperatures will mostly be seen across all but the northwestern quarter of the United States during October, November and December, according to forecaster WSI Corp. of Andover, MA.

"The La Nina event continues to slowly strengthen and play a dominant role in temperature patterns, primarily via modulation of tropical convection patterns and their subsequent downstream impacts in the U.S.," said WSI seasonal forecaster Todd Crawford. "Typically, in the eastern U.S., La Nina means a warm October and a cold December, with the transition occurring in November. While we feel that December will indeed be cold in the East, the current ocean temperature patterns in the northern Pacific suggest that the early fall warmth may not be as certain as the La Nina signal suggests."

In its most recent Energycast Outlook for October, WSI forecasts warmer than normal temperatures across most of the United States, with colder than normal temperatures prevailing across the Northeast and north central regions. Heating demand for gas may be slightly above average from the colder regions, but not enough to offset continued gas injections to storage, according to WSI. Shoulder season power demand will be moderate, but prices may be volatile in areas with high levels of scheduled generator maintenance. In the Northeast, fall generator maintenance programs are low and there are no scheduled nuclear outages in New York or New England. The forecaster said gas demand from the power sector in the northeast will be moderate thanks to moderate temperatures and low nuclear outages.

WSI looks for colder-than-normal temperatures across the central and Northwest regions in November but predicted that early heating demand for gas from those regions should be offset by warmer temperatures elsewhere in the country, particularly the Northeast. Power demand will be moderate due to shoulder-season temperatures. Early cold weather in November could ease pressure on growing natural gas inventories, WSI said.

The WSI forecast for December indicates colder-than-normal temperatures across the northern and eastern regions of the country. Cold weather across all of the key heating demand areas should be bullish for gas prices in December, but supply concerns are likely to be moderated by high natural gas inventories at the start of the heating season in mid-November. Power prices are likely to be influenced more by gas price increases than through increased load induced by cold weather, WSI said.

The WSI seasonal outlooks reference a standard 30-year norm (1971-2000). The next forecast package, for November-January, is scheduled to be issued Oct. 16.

In a separate announcement, WSI said it expects a total of 14 named storms, six hurricanes and four intense hurricanes (Category 3 or greater) during the 2007 Atlantic hurricane season, only a slight change from previous WSI tropical forecasts.

WSI forecasters increased by one the number of intense hurricanes they had previously predicted. The number of storms forecast is larger than the long-term averages of 9.6 named storms, 5.9 hurricanes and 2.3 intense hurricanes, and also larger than the numbers from 2006, WSI said. The main weather drivers for the rest of the season are a continuation of warmer-than-normal temperatures in the western tropical Atlantic basin and a relatively benign vertical wind shear environment associated with the emerging La Nina event.

So far this year tropical storm activity has been slightly above average, with 11 named storms, three hurricanes and two intense hurricanes developing in the Atlantic. Dean, a long-lived Category 5 hurricane, slammed into Mexico's Yucatan Peninsula Aug. 21. Another Category 5 hurricane, Felix, struck portions of Central America Sept. 4, the same day that Henriette, a Category 1 Pacific hurricane, hit Baja California, Mexico. Humberto, a Category 1 hurricane, made landfall Sept. 13 on the Texas coast southeast of Houston.

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