Storm forecasts call for near normal activity

Hurricane Irma Damage
Hurricane Irma ripped the roof of this Pines Trailer Park home in September 2017. - Joe Hendricks | Sun

The 2019 hurricane season should be an average year, with nine to 15 named storms occurring, according to the National Oceanic and Atmospheric Administration (NOAA).

The prediction is in line with the one released last month by Colorado State University, which said there should be 13 named storms this season. The average is 12.1. NOAA forecasts four to eight hurricanes, with two to four of those being major storms.

The Saffir-Simpson Hurricane Wind Scale is a 1 to 5 rating based on a hurricane’s sustained wind speed. Hurricanes reaching Category 3 and higher are considered major hurricanes because of their potential for significant loss of life and damage.

CSU predicts five hurricanes total, with two reaching the major hurricane designation. The average number of major hurricanes in one season is 2.7.

Both forecasts point out that the development of El Nino winds plays a vital role in the number and intensity of storms that occur.

According to a NOAA website, El Nino and La Nina are opposite phases of a natural climate pattern across the tropical Pacific Ocean that swings back and forth every three to seven years on average. Together, they are called El Nino-Southern Oscillation (ENSO.) The ENSO pattern in the tropical Pacific can be in one of three states: El Nino, Neutral, or La Niña. El Nino (the warm phase) and La Nina (the cool phase) lead to significant differences from the average ocean temperatures, winds, surface pressure and rainfall across parts of the tropical Pacific. Neutral indicates that conditions are near their long-term average.

During El Nino, the surface winds across the entire tropical Pacific are weaker than usual. Ocean temperatures in the central and eastern tropical Pacific Ocean are warmer than average during El Nino, and rainfall is below average over Indonesia and above average over the central or eastern Pacific.

What this means during El Nino is more hurricanes in the southern Pacific American coast due to less vertical wind shear and fewer hurricanes in the Gulf of Mexico, Caribbean and tropical Atlantic due to stronger vertical wind shear and trade winds and greater atmospheric stability.