The 2015 Hurricane Season is nearly two-thirds over, and judging by the number of storms alone, it's on track to be a normal year. Nine named storms have formed, and the 30-year average for an entire season is twelve. However, a different measuring tool - accumulated cyclone energy (or ACE) - reveals that the year has been only 25% as active compared to normal. ACE takes into consideration the number, strength, and duration of all the tropical storms over the course of a season. As of Wednesday, that number was 27 and the average for an entire year is 110.
Despite accurate predictions (so far) that the season would be relatively quiet, the United States has seen two tropical storms come ashore. First came Ana, breaking a record for the earliest landfall in U.S history on May 10 near Myrtle Beach, South Carolina. In June, Tropical Storm Bill soaked Texas and caused $17.9 million in flood damage. Claudette followed Bill in early July forming near the coast of North Carolina, but moving out to sea. All three storms developed early in the season and relatively close to the United States.
Since then, there have been seven more tropical systems, two of which became hurricanes. However, none have been able to make it through the semi-permanent hostile conditions over the Caribbean and western Atlantic. This tropical graveyard of sorts has been a product of the strong El Niño that developed in the eastern Pacific Ocean over the summer. The warmer waters produce higher winds aloft that tend to disrupt tropical cyclone development in the Atlantic Basin. With two months of the hurricane season remaining, there is no sign these unfavorable conditions will relax, making it highly unlikely that a tropical cyclone can approach the United States from this direction.
That's not to say a storm still couldn't develop on the other side of this hostile environment and impact the U.S., similar to what happened early in the season. In fact, climatology suggests that tropical cyclone activity does tend to develop in the closer waters of the Gulf of Mexico, western Caribbean or western Atlantic in October and November. It should be noted that the unfavorable conditions caused by the current El Niño are not as prevalent in these regions, and there is less known correlation between this weather pattern and Gulf of Mexico tropical cyclones.
The Atlantic Hurricane Season officially ends on November 30.
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