Following the trend of the last few years, people in the northern and eastern United States might need to don their winter jackets a little earlier than normal if Weather Services International’s (WSI) fall forecast comes to fruition. The Andover, MA-based weather forecaster also said it expects six more named storms to form in the Atlantic Ocean this year.

WSI said it expects the October-December period to average — referencing a standard 30-year norm (1981-2010) — cooler than normal in all of the northern and eastern United States, with above-normal temperatures confined to the Southwest.

“The primary ocean signals suggest the late fall and early winter period will resemble those of the last three years, with an early start to winter in the eastern U.S.,” said Todd Crawford, chief meteorologist at WSI. “While October should be relatively mild across much of the U.S., below-normal temperatures will become more common in the eastern U.S. in November and across all of the northern U.S. by December. The combination of the newly emerging La Nina event and the continued trend toward North Atlantic atmospheric blocking…both support this hypothesis.”

For October, WSI expects the Northeast, North Central, South Central and the Southwest — except coastal California — to experience warmer-than-normal temperatures, while the Southeast and Northwest see cooler-than-normal conditions. With October looking warmer than normal in some key energy demand regions, natural gas demand for power generation could remain stout.

Commenting on the October forecast, Paul Flemming, director of power and gas services at Energy Security Analysis Inc. (ESAI), said that while October is historically a shoulder month for electricity demand, generator maintenance during October results in a lower availability of coal and nuclear plant capacity. “This gap is filled by gas-fired generators and tends to increase the relative gas demand for power, despite lower overall demand for power,” he explained. “With warmer-than-normal temperatures expected in ERCOT, MISO, PJM, New York and New England during October, above-normal seasonal power demand early in the month and the continuation of the generation maintenance period should keep gas demand firm and gas prices from collapsing as the injection season nears its end.”

Due to slightly higher demand in October, Flemming said he expect gas inventory levels “to have trouble challenging last year’s record of 3,840 Bcf by the end of the injection season.” ESAI’s end-of-season storage forecast currently stands at 3,650 Bcf.

The arrival of November is expected to plunge the Southeast and Northeast — except Maine — into colder-than-normal conditions, with the rest of the country experiencing warmer-than-normal readings.

Flemming said the lower early-season gas demand, due to warmer-than-normal temperatures in the North Central and Northwest regions, will be offset by colder-than-normal temperatures in the Northeast and heating demand for gas will likely run slightly below normal in November. “Henry Hub natural gas prices can be expected to pick up slightly from October shoulder season levels as early-winter heating demand begins,” he said. “Gas inventory levels at the start of the withdrawal season should be slightly lower than last year.”

During the last month of the current forecast is when the real cold should begin, according to WSI. The entire country is expected to be colder than normal during December except for the Southwest, Florida and Texas, the forecasting service said.

“In December, much-colder-than-normal temperatures across the northern tier of the U.S. will result in much higher heating demand for gas,” Flemming said. “Typically, early-season cold weather indications are bullish for gas prices, as a long-term cold stretch starting in December could significantly reduce gas inventories. Power prices in the Northeast markets will be supported by colder weather, but warmer-than-normal temperatures in Texas and Florida will moderate power prices in those markets.”

In its final hurricane update of the year, WSI increased its forecast to a total of 21 named storms, including seven hurricanes, four of them intense (Category Three or greater). In its previous forecast, WSI said it expected 18 named storms, including eight hurricanes, four of them intense, to form this year (see NGI, Aug. 29). The long-term (1950-2010) average for the Atlantic Basin is 12 named storms, including seven hurricanes, three of them intense.

The fact that only three of the season’s 15 named storms to date have reached hurricane status “is quite unusual and is likely a reflection of the reduced instability over the Atlantic sector so far this season,” Crawford said.

In previous forecasts WSI had said the Gulf of Mexico (GOM) would be under the greatest threat of hurricane landfall this season, but changing conditions have the forecaster rethinking that prediction.

“Irene was the first landfalling hurricane in the U.S. since Ike in 2008, and all three hurricanes (Irene, Katia, and Maria) so far have recurved before threatening the Gulf States,” Crawford said. “This reflects the continued dominance of the eastern U.S. and western Atlantic troughing that has generally been in place since 2009. The tropical storms (Don, Lee, Nate) that have threatened the Gulf so far have generally underperformed. This is due, in part, to the unseasonably dry air associated with the southern Plains drought. While the near-term pattern may favor more southern tracks and a higher Gulf threat, the expected return of eastern U.S. troughing in late September suggests that our original forecast for enhanced Gulf landfall chances may be in doubt.”

On Friday the National Hurricane Center (NHC) said Tropical Storm Ophelia, the 15th named storm of the year, was becoming weaker in the central Atlantic Ocean about 635 miles east-southeast of the Leeward Islands. Ophelia was moving west at about 16 mph and was expected to turn toward the northwest on Saturday, according to NHC. The storm’s maximum sustained winds had decreased to 40 mph on Friday and were expected to further weaken through the weekend, NHC said.

While the number of tropical storms this year has been relatively high, they have presented only sporadic danger to GOM energy interests. Most have followed trajectories similar to that of Hurricane Maria, which swirled harmlessly well offshore the East Coast before dissipating in the North Atlantic earelier this month.

But four oil workers died after they and six others were forced to abandon a liftboat in the southern GOM during Tropical Storm Nate earlier this month. Tropical Storm Lee forced temporary shut-ins and the evacuation of production platforms and mobile drilling rigs in the GOM (see NGI, Sept. 12a), as did Hurricane Don, though to a lesser extent, earlier in the summer.

Hurricane Irene steered clear of the GOM but turned out the lights on millions of East Coast residents and in doing so cut demand for natural gas by about 2.8 Bcf (see NGI, Sept. 5).

A La Nina weather phenomenon, which contributed to extreme weather around the globe in the first six months of this year, has reemerged in the tropical Pacific Ocean and is forecast to gradually strengthen and continue into winter, according to the National Oceanic Atmospheric Administration (NOAA) (see NGI, Sept. 12b). Seasonal hurricane forecasters factored the potential return of La Nina into NOAA’s updated 2011 Atlantic hurricane season outlook, issued in August, which called for an active hurricane season (see NGI, Aug. 8). forecasters last month predicted a ramping up of tropical activity (see NGI, Aug. 15) and WeatherBELL Analytics chief meteorologist Joe Bastardi in August said he expected tropical storm activity in the Atlantic Basin to increase through this month. A series of tropical forecasters, including Colorado State University (see NGI, June 6) and MDA EarthSat (see NGI, May 23) have predicted above-average tropical storm activity in the Atlantic Basin.

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