A flurry of long range forecasts last week all reached the same conclusion: the 2012 hurricane season is expected to produce fewer tropical storms than the last few years.
Forecasters at the National Oceanic and Atmospheric Administration (NOAA) said there is a 70% chance of nine-15 named storms in the Atlantic Basin, including four-eight hurricanes, with one-three major hurricanes (Category 3 or higher), compared with the 1981-2010 average of 12 named storms, six of them hurricanes, including three major hurricanes.
The continuation of conditions associated with the Atlantic high-activity era that began in 1995, in addition to near-average sea surface temperatures across much of the tropical Atlantic Ocean and Caribbean Sea, favor storm development this year, but strong wind shear and cooler sea surface temperatures in the far eastern Atlantic are likely to limit storm development, NOAA said.
“Another potentially competing climate factor would be El Nino if it develops by late summer to early fall,” said Gerry Bell, lead seasonal hurricane forecaster at NOAA’s Climate Prediction Center. “In that case, conditions could be less conducive for hurricane formation and intensification during the peak months (August-October) of the season, possibly shifting the activity toward the lower end of the predicted range.”
Forecasters at Weather Services International (WSI) said that they too expect a relatively quiet hurricane season this year. The WSI forecast team expects 11 named storms in the Atlantic Basin this year, including six hurricanes, two of them major hurricanes, as it did in its previous forecast issued last month.
Slightly cooler North Atlantic ocean temperatures, combined with a trend toward El Nino conditions, suggest a “notable reduction” in tropical storm activity this year, according to said WSI Chief Meteorologist Todd Crawford.
“For this update, the slight increase in North Atlantic sea-surface temperatures during the last month was offset by slightly higher confidence in El Nino development, resulting in no change to our numbers,” Crawford said. If the trend toward El Nino accelerates, WSI’s forecast numbers could be revised lower, he said.
“Bottom line, the big picture is we’re pretty close to normal in our forecast for the hurricane season in the Atlantic this year,” said James Aman, Senior Meteorologist at Earth Networks, the owner of WeatherBug.
The WeatherBug meteorology team is forecasting 11-13 named storms in the Atlantic Basin, including six to seven hurricanes, with two to four major hurricanes.
“The favorable La Nina conditions noted in 2011 have now ended, with neutral El Nino-La Nina Southern Oscillation conditions expected this summer,” Aman said. “A weak El Nino might develop by this autumn, which could be a slightly negative factor for the latter part of the hurricane season. This will tend to be balanced by the favorable phase of the long-term Atlantic multi-decade cycle. In addition, water temperatures in the Atlantic basin are closer to normal, and are not as warm as they were for the above-normal season in 2011.”
The potential for hurricane landfall in the United States this year “appears to be near normal,” Earth Networks said.
While the hurricane threat for the entire Atlantic basin is lower than in recent years, the United States — especially the Gulf of Mexico and energy interests located there — could be in greater danger from tropical storms, according to Telvent DTN chief science officer Jeff Johnson.
“This year one thing I am concerned about is the warmer water near the U.S. in the western part of the basin,” Johnson said. “That may tend to enhance the early season threat…and then also any storms that maybe develop a little further out could intensify with short notice as they move toward the U.S.” That could lead to shorter lead times as storms approach the Gulf coast and energy interests in that area. “Instead of watching a storm way out in the central Atlantic and knowing about it 10 days ahead, we may see storms pop up with a day notice or two days notice or three days notice in close to the Gulf and off the southeast coast.”
Telvent DTN said it is expecting 11 named storms this year, including six hurricanes, two of them major hurricanes. Other forecasters expecting a relatively quiet hurricane season this year include AccuWeather.com (12/five/two) and Colorado State University (10/four/two). The 1950-2011 average is 12/seven/three and the 1995-2011 average is 15/eight/four.
While last year’s Atlantic hurricane season didn’t bring many tropical storms to Gulf of Mexico energy interests or the North American mainland, it did produce the third-highest number of tropical storms since records began in 1851 and continued a trend of active hurricane seasons begun in 1995 (see NGI, Dec. 5, 2011).
The Atlantic hurricane season, which officially runs from June 1 to Nov. 30, got off to an early start this year with the formation of Tropical Storm Alberto off the coast of South Carolina last weekend. Alberto moved to within 130 miles of Charleston, SC, but was downgraded to a post-tropical cyclone and was moving toward the central Atlantic Ocean by Tuesday.
“I don’t know that you can really read too much into the fact that we had an early season storm,” Aman said. “It may indicate that we do have conditions that are getting close to storm formation…you can’t read too much into it, but it does mean that we’re getting close to the season and atmospherically we’re getting ready to have hurricanes.”
WSI has said it expects temperatures across much of the United States will average above normal this summer, though slightly cooler-than-normal temperatures are expected across the Southeast and Pacific Coast (see related story).
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