2015 Hurricane Season Outlook

One decade after Hurricane Katrina's record-breaking season, what should we expect of the 2015 hurricane season?

The official start to the Atlantic Hurricane Season started earlier this month on June 1st. However, the Atlantic Basin's season was off to an early start with Tropical Storm Ana making landfall along the South Carolina coast on May 10^th –three weeks before the start of the 2015 hurricane season. Also, the Pacific Basin has already seen the development of two category 4 hurricanes, Andres and Blanca. So at this juncture we need to ask if these strong storms are early indicators of a busy hurricane season?

Sea Surface Temperatures (SSTs) over the Atlantic
Ocean measured in Kelvins.
http://www.esrl.noaa.gov

One important variable to analyze while forecasting tropical weather is the impact of an El Nino or La Nina event. You may ask why a natural phenomenon occurring over 3,000 miles away from the United States is important in forecasting? It's important because the effects of the El Nino and La Nina events are felt globally. In respect to the United State's tropical weather, El Nino brings cooler waters and stronger wind shear (subsidence) to the Atlantic Ocean—which suppresses hurricane development. El Nino’s role in this year’s hurricane season still remains undefined; however, we are already seeing El Nino’s effects on our wind and pressure patterns locally and within the mid-Atlantic region. The National Oceanic and Atmospheric Administration’s (NOAA) Climate Prediction Center estimates there is an 80 percent chance of El Nino persisting throughout the rest of the year and the event will be stronger than last year. El Nino is forecasted to strengthen during the peak months of the Atlantic Hurricane season.

Another essential variable to hurricane development is warm sea surface temperatures (SSTs). As of March 2015, warm SSTs were found in the western Atlantic and throughout the Caribbean Sea. Meanwhile, in the eastern Atlantic, SSTs were below average. The cooler than average water and SSTs tend to suppress hurricane development and intensification. It’s significant to bring attention to the location of the warmer SSTs because many damaging hurricanes do form in the western Atlantic Ocean.

NOAA's 2015 Atlantic Hurricane Season Outlook
NOAA.gov

Overall, NOAA is predicting a below average hurricane season with a 70 percent likelihood of 6-11 named storms, 3-6 hurricanes, and 0-2 major hurricanes (category 3 and higher). According to Colorado State University, there is approximately 28 percent chance of at least one major hurricane making landfall along the entire U.S. coastline, 15 percent chance of a major hurricane making landfall on the east coast including Florida, and a 15 percent chance that the area from the Gulf Coast to Brownsville, Texas will see the landfall of a major hurricane. These predictions come from statistical predictors and dynamic models combining SSTs, sea level pressure, and upper and lower atmospheric conditions, such as wind shear and wind patterns. A low number of tropical storms does not necessarily mean that the storms which do develop won’t be strong or have destructive capacity. NOAA Administrator Kathryn Sullivan, Ph.D. warns, “A below-normal season doesn’t mean we’re off the hook. As we’ve seen before, below-normal seasons can still produce catastrophic impacts to communities.”


For safety and preparation tips during hurricane season, please review my article from last year's season, Summer Travel and Weather Advisories. No matter where your travels take you this summer, be aware of the always changing weather!

-Katie Thomas