When the 2011 Atlantic hurricane season officially begins Wednesday (June 1), it will usher in five months of active tropical storm production, including a “significant threat for hurricane landfall” in the Gulf of Mexico (GOM), forecasters at Andover, MA-based WSI Corp. said last week.

“Most of the important drivers for tropical activity continue to indicate that an active-normal season lies ahead of us,” said WSI Chief Meteorologist Todd Crawford.

And some of the same meteorological conditions that will help to form those hurricanes will also drive temperatures higher than normal across much of the country this summer, the forecasters said.

WSI reaffirmed the forecast of 15 named storms, including eight hurricanes, four of them Category Three or greater — the same as the 1995-2010 average — which it first released in April (see NGI, May 2). Atlantic sea surface temperatures are near 1995-2010 mean values and WSI doesn’t expect either an El Nino or La Nina event to develop this summer, Crawford said.

“We do expect another active season in 2011, although not to the level of 2005 or 2010. However, while we expect less overall activity this year than last, we do expect a much more impactful season along the U.S. coastline. The U.S. has been spared from any landfalling hurricanes since 2008 and the hurricane drought in 2009 and 2010 is relatively rare in the historical record. In fact, the U.S. has not had a three-year stretch without a hurricane landfall since the 1860s.”

The Gulf Coast is under a significant threat for hurricane landfall in the upcoming season, according to WSI, which said it expects two or three landfalling hurricanes this year.

“The lack of U.S. landfalls in 2010 was primarily due to a persistent western Atlantic trough that essentially protected the U.S. East Coast from any direct hits,” Crawford said. “We do not expect this feature to be in place this year during late summer and fall when most tropical storms occur. Further, the Gulf and Caribbean sea surface temperatures are particularly warm this year, and we expect more development in these regions and less in the eastern tropical Atlantic. Storms developing in the Gulf and Caribbean are a much greater threat to make landfall along the U.S. coast than those that develop off the coast of Africa.”

The WSI forecast numbers remain above the longer-term 1950-2010 average of 12 named storms, including seven hurricanes, three of them intense. A total of 19 named storms formed in 2010, with 12 of them becoming hurricanes, including five intense hurricanes (see NGI, Dec. 6, 2010).

Forecasters at the National Oceanic and Atmospheric Association (NOAA) have said they expect the 2011 Atlantic hurricane season will produce above-normal numbers of tropical storms and is likely to be more damaging to the United States than the 2010 season (see NGI, May 23), and MDA EarthSat Weather has said it expects an active hurricane season, with warming sea surface temperatures in the Pacific helping to form 14 named storms, including seven hurricanes, five of them intense. AccuWeather.com forecasters, who have also predicted a higher-than-normal number of tropical systems with more direct impacts on the United States than last year, have said any effects of hurricanes on the energy industry — including spiking prices for gasoline — aren’t likely to last long.

The Ohio Valley and Great Lakes areas can expect temperatures to average cooler than normal over the next three months, while the rest of the country will have a warmer-than-normal summer, according to WSI Corp.

“May has been a rather chilly month across most of the U.S. so far as the atmospheric pattern has changed to allow cooler weather to temporarily return to the southern U.S. This change in the pattern towards increased high-latitude blocking, or a more amplified jet stream, will likely persist and evolve into June,” Crawford said. “Because of this, we expect the coolest part of summer (relative to normal) to be early, especially across the north-central and Great Lakes states. During the last half of summer, we think that the pattern will reverse with the potential for some significant heat to return to the northern U.S. by August.”

The Northeast (except western New York, Pennsylvania and Vermont), Southeast, South Central and Southwest areas will see warmer-than-normal temperatures in June, while the North Central and Northwest will average cooler than normal, WSI said in a forecast issued Monday. The warmer-than-normal temperatures in New England and the Atlantic and Gulf Coast regions “will provide a bullish underpinning for power prices,” Paul Flemming, Energy Security Analysis Inc. (ESAI) director of power and gas, said in a statement issued in conjunction with WSI’s outlook.

“However, cooler-than-normal temperatures will prevail in most areas of New York and PJM moderating prices overall in those pools. The cooler-than-normal temperatures in California and the Northwest, as well as ample hydro, will be bearish for power prices in those markets. Given the expected weather patterns and the return of most generation from maintenance, gas demand should be near normal for June,” Flemming said.

By July WSI sees cooler-than-normal temperatures moving into the East and South Central (except western Texas) United States, while temperatures are expected to average warmer than normal in the North Central area and in the inland portion of the Northwest. The relatively lower temperatures in key demand centers should result in lower-than-normal natural gas demand, Flemming said.

“The cooler-than-normal temperatures in the eastern regions will also result in lower power prices and less price volatility in the PJM, New York and New England control areas during July. Cooler temperatures will also translate into lower probabilities of heat events during July,” he said.

As WSI forecasters had hinted in their previous outlook, August promises to be warmer than normal nationwide (with the exception of the Mississippi and Ohio river valleys).

“Much warmer-than-normal temperatures in the key eastern and western markets will result in greater natural gas demand to meet power sector demand for cooling,” Flemming said. “The warmer outlook increases the chances of heat events in August that could result in price spikes in the Northeast and California markets.”

WSI is scheduled to issue its next seasonal outlook on June 21.

©Copyright 2011Intelligence Press Inc. All rights reserved. The preceding news reportmay not be republished or redistributed, in whole or in part, in anyform, without prior written consent of Intelligence Press, Inc.