Temperatures across most of the eastern and southern United States will average above normal over the next three months, while the northwest and North Central regions can expect cooler-than-normal temperatures, according to Andover, MA-based WSI Corp.

The current La Nina — a cooling of ocean surface temperatures off the western coast of South America — is diminishing but continues to be the primary driver of weather patterns in the northern hemisphere, according to WSI Chief Meteorologist Todd Crawford.

“In general, this means colder-than-normal temperatures across Canada and the northern U.S., with above-normal temperatures across much of the southern and eastern U.S.,” Crawford said. “The big wild card as we head towards summer is the [North Atlantic Oscillation] and whether the recent multi-year stretch of an ‘activated’ North Atlantic pattern will continue. If it does, a summer similar to 2008 is a likely outcome, with cool central U.S. temperatures surrounded by warm temperatures in much of the southern and eastern U.S. If the recent stretch of quiet North Atlantic conditions persists into summer, a much warmer summer in the northern U.S. is likely, with below-normal temperatures across the Southeast.”

The National Oceanic and Atmospheric Administration recently predicted that La Nina conditions could persist but should be weaker, if not neutral, by May or June (see Daily GPI, Feb. 23).

WSI’s forecast for April calls for temperatures to average warmer than normal in the East and South Central areas, with colder-than-normal temperatures spread across the rest of the country.

“Weather-related demand in April typically has minimal effect on gas demand, but the warmer-than-normal temperatures in the Mid-Atlantic region and Northeast will help to minimize any lingering heating demand in the Consuming East,” Energy Securities Analysis Inc. Senior Analyst Chris Kostas said in a statement issued in conjunction with WSI’s outlook. “PJM is expecting an above-normal nuclear maintenance season, however, and this should increase demand for natural gas as gas-fired generators are called upon to replace the missing baseload generation. Implied market heat rates in PJM may be firmer than normal despite the lower-than-normal weather-related demand.

“Cooler-than-normal temperatures in [the Midwest Independent Transmission System Operator area] and the West in April should only have a marginal effect on aggregate U.S. heating demand but should combine with the slightly increased nuclear maintenance season in the East to provide slightly above-normal gas demand for the month.”

WSI’s forecast map does an about-face for May, with cooler-than-normal temperatures expected in the East (except Florida) and North Central areas, and warmer-than-normal temperatures forecast in the West and South Central areas. Power prices may be soft in the Northeast, Mid-Atlantic and Great Lakes regions in May, but heat rates could be normal — or even above normal — in PJM due to soft gas prices and delayed returns from maintenance by some coal-fired generators, Kostas said.

“Slightly warmer-than-normal temperatures in the ERCOT [Electric Reliability Council of Texas] and South will increase power prices and heat rates in that region in response to the slightly above-normal cooling demand. An above-normal hydro season in the Northwest and California should provide enough generation to offset the increased cooling demand in the West in general, and in California specifically,” he said.

By June WSI sees warmer-than-normal temperatures returning to the East, with cooler-than-normal temperatures confined to the North Central and Northwest areas. That should provide upside pressure on power prices and implied market heat rates in New York, New England and Eastern PJM, according to Kostas.

“The cooler-than-normal temperatures in Western PJM, however, will likely keep prices there subdued and could provide for added west-to-east price separation between Northern Illinois and PJM Western Hub.” At the same time, ERCOT should get weather-related support for power prices and heat rates, he said.

WSI’s forecast was generally in line with recent predictions from AccuWeather.com chief long-range forecaster Paul Pastelok, who has said he expects colder-than-normal conditions to remain in place through April in areas from the Pacific Northwest through much of the Plains, with “more back and forth” between cold and warm temperatures for the East Coast and much of the Southeast.

WSI is scheduled to issue its next seasonal outlook, which will include its first summer forecast, on April 26.

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