Posted: 4:48 pm Saturday, March 15th, 2014
By John Nelander
What is the key to improving Atlantic hurricane forecasts? Perhaps more of an emphasis on a phenomenon known as the Madden-Julian Oscillation (MJO), a cyclical pattern that travels around the world’s tropical oceans from west to east and helps kick-start low pressure areas and rainfall.
Meteorologists have been studying the phenomenon since the 1970s. But on the eve of the release of the upcoming 2014 pre-season hurricane forecast, Colorado State University researcher Philip Klotzbach takes a closer look at the MJO in a paper published today by the Journal of Climate.
Tropical storm and hurricane production is based on a wide range of factors, including sea surface temperatures, sinking air that causes high pressure in the Atlantic, and the presence of Saharan dust that moves off the West Coast of Africa. But the MJO influences more than just air pressure, Klotzbach says. It also has an impact on wind shear and available moisture.
“The Atlantic basin typically shows the smallest modulations in most large-scale fields of any tropical cyclone basins,” he said in the paper, “The Madden-Julian Oscillation’s Impacts on Worldwide Tropical Cyclone Activity.” However, he said, its impact is still significant.
“The number of rapid intensification periods are also shown to increase when the convectively enhanced phase of the MJO is impacting a particular tropical cyclone basin,” he said.
MJO cycles run from 30 to 60 days, and start in the Indian Ocean and move into the Western Pacific. By the time the pattern reaches the Atlantic Basin it’s harder to follow. But it still may be an important clue to shorter-term hurricane forecasting, since MJO patterns can be forecast two weeks in advance.
MJO information has been available since 1979, but now researchers are developing a new set base going back to as early as 1905. That could supply even more clues to the role this phenomenon has played during some of the most active Atlantic hurricane seasons.
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RAINFALL FORECAST UNCERTAIN: It looks like Monday’s Gulf of Mexico system may have more of an impact on Central and North Florida, although the Palm Beach area is not entirely off the hook. The latest computer model runs show the low slowing up as it approaches the peninsula, which could keep a lid on atmospheric instability to the south, forecasters said today.
Nevertheless, rain chances increase to 60 percent on Monday with winds gust up as high as 36 mph. It’s unclear what kind of squall line might develop as the storm moves across the state, so check local forecasts later in the weekend.
The National Weather Service’s Weather Prediction Center shows the heaviest rain occurring in Northwest Florida, with light amounts south of Lake Okeechobee. Parts of the Florida panhandle could get ore than 2 inches.
About the Author
John Nelander is a freelance writer, book editor and publisher in West Palm Beach. Weather Matters features news and observations about the weather with a focus on what's happening in South Florida. The blog also looks at the latest studies on climate change as well as what's happening in the weather forecasting biz. His website is www.pbeditorialservices.com.