The Colorado State University (CSU) team, the gold standard for hurricane forecasting, continues to predict below-average 2018 Atlantic hurricane season.
CSU hurricane researchers continue to predict a below-average Atlantic hurricane season. They cite both a cooler than normal tropical Atlantic and the potential development of a weak El Niño event as the primary reasons for the below-average prediction.
The tropical Atlantic remains much colder than normal. A colder tropical Atlantic provides less fuel for developing tropical cyclones. Vertical wind shear was much stronger than normal across the Caribbean in July. This also tends to be associated with quieter Atlantic hurricane seasons. The tropical eastern and central Pacific is currently slightly warmer than normal. There is the potential that El Niño conditions could develop over the next few months. If this occurs, it would tend to increase vertical wind shear in the tropical Atlantic, tearing apart hurricanes as they try to develop.
The CSU Tropical Meteorology Project team is predicting a total of nine additional named storms to form after Aug. 1. Of those, researchers expect three to become hurricanes and one to reach major hurricane strength (Saffir/Simpson category 3-4-5) with sustained winds of 111 miles per hour or greater. These forecast numbers do not include Tropical Cyclones Alberto, Beryl and Chris which formed prior to Aug. 1.
The team bases its forecasts on over 60 years of historical data that include Atlantic sea surface temperatures, sea level pressures, vertical wind shear levels (the change in wind direction and speed with height in the atmosphere), El Niño (warming of waters in the central and eastern tropical Pacific), and other factors.
So far, the 2018 hurricane season is exhibiting characteristics similar to 1968, 1986, 1993, 1994 and 2002.
“All of these analog seasons experienced below average Atlantic hurricane activity,” said Phil Klotzbach, research scientist in the Department of Atmospheric Science and lead author of the report.
The team predicts that 2018 hurricane activity will be about 70 percent of the average season. By comparison, 2017’s hurricane activity was about 245 percent of the average season.
This is the 35th year that the CSU hurricane research team has issued the Atlantic basin seasonal hurricane forecast. The late William Gray, professor in the Department of Atmospheric Science for over 40 years, launched the report in 1984.
Meteorologist are using the latest data and historical research to let us know what we might expect from the Hurricane Season in August this year. We're watching and listening.
"Tropics have been pretty quiet but the fastest increase in activity is this month climatologically," posted James Wieland [@SurfnWeatherman], Meteorologist/reporter/surf forecaster for NBC NewsChannel5, WPTV.
"Here's where most tropical systems develop and move in the month of August," Mr. Wieland posted (Image above).
A transition to El Niño may mean a quieter hurricane season than originally predicted.
El Niño is a part of a routine climate pattern that occurs when sea surface temperatures in the tropical Pacific Ocean rise to above-normal levels for an extended period of time.
“We’re definitely looking at a different season than last year,” said Paul Pastelok, AccuWeather Long-Range Forecaster. "Two to three U.S. impacts are predicted, and forecasters will have their eyes on the southeastern Gulf heading into September."
"Vertical wind shear over the past 30 days has been much stronger than normal over the Caribbean and near normal further east in the tropical Atlantic, said Philip Klotzbach [@philklotzbach], Colorado State meteorologist that specializes in Atlantic Basin hurricane forecasts. "Above-normal shear in the Caribbean in July typically correlates with less active Atlantic hurricane seasons."
"August continental US #hurricane landfall locations since 1851," said Mr. Klotzbach. "Florida has been hit by the most hurricanes in August (23), followed by Texas (17) and then Louisiana (11) and North Carolina (11)."