Forecasting company, Tropical Storm Risk (TSR), has released its prediction for the upcoming Atlantic storm season. The company predicts Atlantic hurricane activity in 2020 will be 25% above the long-term norm. However, this outlook has large uncertainties.
Based on current and projected climate signals, Atlantic basin tropical cyclone activity is forecast to be 25% above the 1950-2019 long-term norm and 5-10% above the recent 2010-2019 10-year norm. The forecast spans the period from 1st June to 30th November 2020 and employs data through to the end of March 2020.
TSR raises its extended range forecast issued in mid-December 2019 due to updated climate signals pointing towards environmental fields in August-September 2020 that are more favourable for Atlantic hurricane activity than thought previously. These anticipated fields are warmer than normal tropical North Atlantic water temperatures and neutral-to-weak La Niña ENSO (El Niño Southern Oscillation) conditions.
TSR use what the ACE Index, which is a calculation of the sum of the squares of 6-hourly maximum sustained wind speeds in knots for all systems while they are at least tropical storm strength. It predicts 130 storms during the season whereas the 70 year average is 104. The last ten years has seen that average sit at 122, showing a continued increase of storm activity over the recent decades.
The modelling shows three intense hurricanes in Category 3 to 5, which is the average for the past 70 years; plus eight Category 1 to 3 hurricanes, which is two above average and 16 tropical storms, which is four above.