The months of August through October are likely to bring little let-up from the warmer-than-normal temperatures that have settled across most of the United States, WSI forecasters said last week.

However, because of the slow start to the 2010 Atlantic hurricane season, the forecasters last Tuesday lowered their expectations to 19 named storms from 20, while keeping a prediction that there will be 11 hurricanes and five intense hurricanes, signified as Category 3 or greater. The forecast was issued before the latest tropical disturbance appeared to head for the Gulf of Mexico.

As to the warm temperatures, the Andover, MA-based forecasters said the only areas of the country to escape the warm breezes and stifling temperatures for the next three months will be parts of the Southeast and California’s coastal cities. WSI issued a similar forecast last month.

“The newly emerging La Nina event, a relatively cold north Pacific, and a record warm North Atlantic are quite bullish for a very warm late summer and early fall period,” said WSI Chief Meteorologist Todd Crawford.

High soil moisture levels across the Plains, combined with few drought conditions in the country, may “temper the overall magnitude of the heat a little,” Crawford said. However, the coming three-month period “we are forecasting 571 population-weighted cooling degree days, 15% more than both last year and the 1971-2000 mean.”

Energy Securities Analysis Inc.’s senior analyst Chris Kostas commented on WSI’s forecast and its possible effect on natural gas power demand in the next few months.

“WSI is forecasting warmer-than-normal temperatures in the Northeast, Midwest and Northwest with much warmer-than-normal temperatures” in the Central Rockies, said Kostas. Slightly cooler-than-normal temperatures are expected in Texas, the South and along the California coast.

“Gas demand from the power sector will run slightly above normal on-balance with continued firm implied market heat rates in PJM and the Northeast,” said Kostas. “Gas prices are unlikely to move significantly higher on the August heat, however, as cooler temperatures in California and the South will combine with strong production figures to keep the market well supplied.”

Warmer-than-normal temperatures are forecast for September across most of the country, with the exception of the Southeast and along the California coast.

“Although seasonal temperatures in the North begin to decline below levels that draw significant cooling demand in September, generator maintenance in PJM will begin the second week of the month,” Kostas said. “This should keep Northeast heat rates firm and gas demand above normal through the end of summer.”

The above-normal weather-related demand in September “will be needed to keep gas prices from collapsing under the weight of increasing shale gas production and rising inventory levels,” Kostas added. “Prices should be supported, but we do not expect much upside without a hurricane disruption.”

In October WSI expects warmer-than-normal temperatures “throughout nearly the entire country” except the Pacific Coast. The largest anomalies above seasonal normal temperatures are forecast for the Northeast and Midwest.

“Although Northeast power demand and heat rates should be firm on higher-than-normal cooling demand, the increase in gas demand for power will be more than offset by the reduction in heating demand in the Consuming East,” said Kostas.

“An extension of the summer cooling season in the South, however, will increase gas demand in the Producing Region On balance, gas demand is likely to begin October above normal but end the month below normal. This should pressure spot prices lower as the injection season wraps up.”

Prior to its reduction in named hurricanes last week, WSI had bumped its expectations higher no less than three times since the original January forecast, when it called for 13 named storms, including seven hurricanes, with three of them intense. WSI bumped up the storm forecast in April to include 16 named storms, including nine hurricanes, five of them intense, and in May the forecast changed to 18 named storms, including 10 hurricanes, five of them intense. Last month WSI jumped the storm forecast to 20, 11 and five, respectively (see NGI, June 28).

Although forecasters now expect fewer hurricanes this season, they warned that the new 2010 forecast numbers are still well above the long-term (1950-2009) averages of 10 named storms, six hurricanes, and two intense hurricanes and slightly above the averages from the more active recent 15-year period (1995-2009) of 14/eight/four.

WSI said its hurricane landfall forecasting model (developed in collaboration with reinsurance intermediary Guy Carpenter) continues to suggest that the coastal region from the Outer Banks of North Carolina northward to Maine is twice as likely as normal to experience a hurricane this year. The forecasting service noted that its model suggests the threat to the Northeast coast this season is on par with that in Florida and the Gulf coastal states.

“Record warm tropical Atlantic ocean temperatures and an enabling wind shear environment should result in a very active tropical season this year,” said Crawford. “The El Nino event has vanished completely, resulting in a decrease in central tropical Pacific convection and a concomitant decrease in the vertical wind shear that typically acts as a detriment to tropical Atlantic development. More importantly, however, eastern and central tropical Atlantic sea surface temperatures are currently at record warm levels for July, even warmer than the freakishly active season of 2005. Water temperatures are already at levels more typical of late August.

“While all of the primary drivers are strongly enabling for tropical activity, we have had a slow start relative to other very active seasons. Further, a pocket of very dry air in the tropical Atlantic will likely limit development in the near term. Because of these factors, we have decreased our forecast total number of named storms from 20 to 19. We still expect an extremely active August-October period.”

WSI’s next update for the 2010 tropical season is to be released on Aug. 25.

The National Oceanic and Atmospheric Association in mid-July said it still expects the 2010 Atlantic season to be “active to extremely active,” with 14-23 named storms, including eight to 14 hurricanes, and three to seven of them being intense (see NGI, July 19).

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