The final six weeks of the 2009 Atlantic Hurricane Season are now upon us. This means the chances for hurricane development are fading rapidly. Not helping matters is El Nino, along with other seasonal weather conditions in the tropics, which are reducing hurricane chances for the remainder of the season.

In a typical hurricane season, the last six weeks running from now until the season`s November 30 conclusion are one of the least active periods of the season. The main culprits are the cooling ocean temperatures across the Tropical Atlantic, Caribbean and Gulf of Mexico and increasing upper-level westerly winds diving south with the autumn season.

The longer nights and subsequent shorter days, along with cooler air diving south across the North American continent cause water temperatures throughout the tropics to begin to lose the stored energy it gained throughout the summer months. Water temperatures begin to decrease, generally from north to south, below the critical 80-degree temperature threshold tropical systems need to grow into tropical storms and hurricanes.

The changing seasons also bring increasing upper-level winds throughout the tropics. These winds produce vertical wind shear which tears apart the delicate horizontal development tropical systems need for development.

This year, El Nino, or the warming of the tropical Pacific Ocean off of South America, is adding to the decreased hurricane risk. El Nino helps increase westerly winds over the tropics, increasing the shear further and making it even harder for storms to develop.

Even so, there is still a slim chance that a tropical system could develop before the season concludes. The most likely spots are in the extreme southwest Caribbean and the Bay of Campeche. These areas, historical locations for October and November development, continue to have water temperatures above 80 degrees and are far enough south to see weaker shear.

Be sure to keep WeatherBug active to receive the latest on the waning weeks of the 2009 hurricane season and get the latest updates anywhere on Twitter at WeatherBug WeatherBuzz.

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