What Does the 2019 Atlantic Hurricane Season Have in Store?
The slightly above-average 2018 Atlantic hurricane season officially ended on November 30, but initial outlooks have already been issued for the 2019 Atlantic hurricane season. The season officially starts on June 1. The Tropical Meteorology Project (TMP) at Colorado State University will release its first full forecast on Thursday, April 4. They recently produced a preliminary discussion where they evaluated the likelihood of several hurricane activity scenarios. The TMP is currently giving an approximately 35% chance of an above-normal hurricane season, a 50% chance of a near-normal hurricane season and a 15% chance of a below-normal hurricane season for the Atlantic basin in 2019. For reference the average Atlantic hurricane season has about 12 named storms (maximum winds >= 39 mph), 6 hurricanes (maximum winds >= 74 mph) and 3 major hurricanes (maximum winds >= 111 mph).
This forecast was based on the premise that North Atlantic sea surface temperatures are currently slightly below-normal across the far North Atlantic and the tropical Atlantic (Figure 1). In general, the tropical Atlantic has been slightly cooler than normal over the past several months, providing a slight inhibiting factor for Atlantic hurricane formation. Warmer-than-normal sea surface temperatures provide more fuel for developing Atlantic storms.
The development of El Niño (warmer than normal water temperatures in the eastern and central tropical Pacific) is likely during the next couple of months, but there is considerably uncertainty as to whether the El Niño would persist through next year’s hurricane season. El Niño typically produces stronger vertical wind shear (the change wind direction with height in the atmosphere) in the Atlantic basin, tearing apart hurricanes as they are trying to develop.
The U.K.-based Tropical Storm Risk produced their first forecast for the 2019 season on Tuesday, December 11. Their initial forecast calls for a total of 12 named storms, 5 hurricanes and 2 major hurricanes, or a slightly below-normal season. Their outlook was based on the premise that tropical Atlantic low-level winds are predicted to be slightly greater than the long-term average, because of a weak El Niño event and slightly cooler than normal tropical Atlantic sea surface temperatures.
Seasonal hurricane outlooks issued in December historically have low levels of skill, since there is a lot that can change in the atmosphere-ocean system between December and the start of the hurricane season in June. Consequently, it is advisable to treat these initial forecasts with caution. Historically, the skill of these outlooks increases as the Atlantic hurricane season approaches. It is also important to note that regardless of the levels of overall hurricane activity experienced in any season, it takes only one significant landfalling hurricane to make it an active season. During the offseason is a great time to make sure that you have reviewed your disaster recovery plan.
Figure 1: Early December 2018 sea surface temperature anomalies across the North Atlantic.
Want to prepare early? Read Interstate's Hurricane Preparedness: Top Tips for Hurricane Season blog article for some great resources and early planning suggestions.
About the Author:
Dr. Phil Klotzbach has received national and international attention for his work in researching weather patterns and forecasting hurricanes. He currently is lead author on Colorado State University's Atlantic basin hurricane forecasts which he releases every year with his colleague Dr. Michael Bell.