Colorado State University Researchers Update 2021 Atlantic Hurricane Season Outlook
On Thursday, Colorado State University updated their 2021 Atlantic hurricane season outlook.
Earlier this year, CSU forecasted 17 named storms with 8 of them becoming hurricanes and 4 of those becoming major hurricanes (Category 3 or above). This was compared to the Atlantic hurricane season averages (based on the 1991-2020 Atlantic hurricane seasons). On average, there are 14 named storms and 7 of those become hurricanes. Then, 3 of the hurricanes have the potential to become major hurricanes. Thus, back in April, Colorado State University was forecasting an above average season.
In their updated forecast, Colorado State University is still forecasting an active season, but they have changed the number of named storms and hurricanes. They increased the number of named storms from 17 to 20 and the number of hurricanes from 8 to 9. They want it to be noted that the number of named storms does include the following tropical systems that have formed so far this season: Ana, Bill, Claudette, Danny & Elsa.
There were a couple factors that CSU researchers thought of when changing the forecast. First, researchers considered the El Niño-Southern Oscillation (ENSO), which is a recurring climate pattern involving changes in the temperature of the waters in the central and eastern tropical Pacific Ocean. This warming and cooling pattern affects rainfall distribution in the tropics and weather across the US.
Currently, we are experiencing neutral ENSO conditions, which La Niña or El Niño conditions are not present. Generally, sea surface temperatures, tropical rainfall patterns and atmospheric winds are close to average in equatorial Pacific Ocean. But, according to NOAA, there is the possibility of La Niña conditions later in the season. Plus, NOAA’s climate website states that there is a La Niña Watch in effect as experts believe there is a 55% chance that La Niña conditions return this fall/winter. These conditions typically support active hurricane seasons as SSTs in the Atlantic are warmer than average and tropical Atlantic trade winds are weak. CSU researchers explained in their updated outlook that SSTs across the tropical Atlantic are near to slightly above normal, while the subtropical North Atlantic is warmer than normal. Remember, warmer SSTs can help intensify tropical systems and give these storms the fuel to form. Plus, they noted that Elsa’s development and intensification into a hurricane in the tropical Atlantic is a sign of an active season.
Colorado State University researchers also said that they are anticipating an above normal probability for major hurricanes making landfall along the US coastline and in the Caribbean. But, whether it just be a tropical storm or a hurricane: it only takes one.
Stay weather aware with the 47 ABC Storm Team this hurricane season.