…the last forecast

The spring hurricane forecasts wrapped up last week when the U.S. National Oceanic and Atmospheric Administration (NOAA) issued its outlook for the 2010 season.  Like their colleagues at Colorado State University (CSU), the NOAA team expects an “above normal” storm lineup this year.  Lead forecaster Gerry Bell noted “The main uncertainty in this outlook is how much above normal the season will be”.

Both teams noted that we are just past the halfway point in a long cycle of high storm activity that started in 1995.  North Atlantic sea surface temperatures are still significantly warmer than those in the South Atlantic.  Also, sea surface air pressures in several critical areas are lower than normal, producing weaker trade winds and less cooling.  Both conditions result from the long-term (several decades) cycle of Atlantic ocean currents.  This circulation is now moving warmer, saltier water past tropical storm nurseries like North Africa and the Azores.

Last year, a chilly winter and a steady flow of Sahara dust kept sea surface temperatures in our area cooler than usual.  This delayed early-season storm formation.  In fact, it was the second week of August before the first named storm (Ana) appeared.  Meanwhile, an El Niño (warm current) was developing in the eastern Pacific.  The rising warm air from this current either broke up or blew away some of the late-season storms.

Neither of these limiting factors will be around in 2010.  NOAA is already reporting record sea surface temperatures in the tropical Atlantic and Caribbean, mainly because of weaker than normal northeasterly trade winds early this year.

The El Niño was weakening in the early months of this year, and the CSU team, in their April forecast, expected it to be “no more than a neutral factor” in the 2010 outlook.  NOAA, with a few more months of data to rely on, suggests that eastern Pacific conditions could actually reverse.  Formation of a La Niña (cold current) would support normal-to-strong trade winds, carrying storms into the Caribbean basin, and create less vertical wind shear, allowing the storms to continue developing.  The result would be storm activity near the higher end of NOAA’s forecast range.

The NOAA forecasters don’t comment on where hurricanes might land, but they note that “the historical probability for … multiple hurricane strikes in the region around the Caribbean sea increases sharply for exceptionally active seasons”.  In other words, when there’s a lot going on, everybody gets some.
Finally, NOAA warned that “It only takes one hurricane (or tropical storm) to cause a disaster. Residents, businesses, and government agencies of coastal and near-coastal regions are urged to prepare for every hurricane season regardless of this, or any other, seasonal outlook.”

Jamaica’s Office of Disaster Preparedness and Emergency Management (ODPEM) has good material on getting ready for hurricanes, including checklists for households and for farmers.  This material is available either on the website (www.odpem.org.jm) or from parish offices in Falmouth, Montego Bay, Lucea and Savanna La Mar.