Barcelona Supercomputing Center, 2016 - Legal Notice

Post Mortem 2019

The 2019 Atlantic basin hurricane season came to an end on November 30. The season ended up slightly above normal with a total of 18 named storms, 6 hurricanes, 3 major hurricanes and an Accumulated Cyclone Energy (ACE) of 130. Final ACE values may change slightly in post-season reanalysis of tropical cyclone intensity by the National Hurricane Center. The 1981-2010 average values of these quantities are 12 named storms, 6 hurricanes, 3 major hurricanes and an ACE of 106. While the season was extremely active for the number of named storms, seven of the named storms that formed in 2019 lasted 24 hours or less – the most to last <=24 hours on record.

In general, Atlantic seasonal hurricane forecasts called for a near to slightly above-average Atlantic hurricane season at lead times from March through early August. Seasonal forecasts increased slightly from March/April outlooks to July/August outlooks, given the slightly faster dissipation of El Niño conditions and some anomalous warming of the tropical Atlantic.   Overall, the peak of the Atlantic hurricane season (August-October) was characterized by slightly above-normal sea surface temperatures and below-normal shear across the tropical Atlantic and Caribbean.

The average values predicted by all groups issuing forecasts in March/April were 13 named storms, 6 hurricanes, 3 major hurricanes and an ACE of 101. These numbers increased slightly in May/June to 13 named storms, 7 hurricanes, 3 major hurricanes and an ACE of 113. The average prediction issued in July/August called for 13 named storms, 7 hurricanes, 3 major hurricanes and an ACE of 109. It should be noted that not all forecast groups issue predictions for all four tropical cyclone intensity metrics. In terms of Accumulated Cyclone Energy, the most accurate March/April seasonal forecast came from CFAN (126 predicted vs. 130 observed), the most accurate May/June seasonal forecast came from WeatherTiger (120 predicted vs. 130 observed), and the most accurate July/August seasonal forecast came from NOAA (135 predicted vs. 130 observed).

The 2019 Atlantic hurricane season was quiet in August, very active in September and above-normal in October for named storm activity but below normal for ACE. The most notable storm of the 2019 season was Hurricane Dorian, which devastated the northwestern Bahamas, resulting in over 60 fatalities and costing billions of dollars in damage. Dorian also brought ~1 billion dollars in damage to the southeast United States while making landfall as a Category 1 hurricane near Cape Hatteras. It was also responsible for 9 fatalities in the continental US. The costliest named storm of the 2019 season for the continental US was Tropical Storm Imelda, which while only being a weak tropical storm when it made landfall, deluged southeast Texas with torrential rainfall, causing ~2 billion in damage and resulting in five fatalities.

A more in-depth discussion of the 2019 Atlantic hurricane season is available from Colorado State University.

Listen to the discussion on the 2019 hurricane season recording - with the participation of L.P. Caron (BSC), P. Klotzbach (CSU) and R. Truchelut (WeatherTiger).