The 2020 Atlantic hurricane season has been off to a historic start. Nine named storms have formed so far, including two hurricanes (Hanna and Isaias). Nine named storms is the most on record through this date, surpassing the 2005 season, which had the most named storms on record (28). However, Accumulated Cyclone Energy is much lower than 2005, since most of the storms have been weak and short-lived and only two have reached hurricane strength. It should be stressed, though, that the Atlantic’s average first hurricane doesn’t form until around August 10 on average, and one hurricane has already formed. Despite the fact that most storms have been weak thus far, Accumulated Cyclone Energy is about twice the long-term average through this date.

The record-breaking start, as well as a combination of well above-normal sea surface temperatures across the tropical Atlantic, below-normal wind shear in the deep tropics, a wet African Sahel region, and a favorable base state are likely to make the 2020 Atlantic hurricane season one of the most active seasons on record. This is by far the highest forecast Cyclonic Fury has ever released, and it is a distinct possibility the naming list could be exhausted this season. If that happens, the Greek Alphabet names will be used.

Atlantic Sea Surface Temperatures

Over the past month, sea surface temperatures (SSTs) in the Atlantic Main Development Region (MDR) and Caribbean have been significantly above average. According to meteorologist Michael Lowry, from July 1-24, SSTs in the Atlantic MDR were the third-warmest on record, trailing only 2005 and 2010 – both hyperactive hurricane seasons. Warmer than normal sea surface temperatures in this region during July-August are well correlated with active Atlantic hurricane seasons. Thus far, in the MDR, we have already seen Tropical Storm Gonzalo develop. Pre-August development in this region is also typically a sign of an active Atlantic hurricane season. The subtropical Atlantic is also generally warmer than normal. Although there is a slight negative correlation with warmer than normal SSTs and Atlantic hurricane activity in May, this correlation disappears later in the season. It appears the Atlantic sea surface temperature anomaly pattern is highly favorable for hurricane activity, potentially in both the deep tropics and subtropics.

El Niño Southern Oscillation/ENSO

A major challenge of forecasting Atlantic hurricane activity prior to the start of the season is the ENSO Spring Predictability Barrier. However, this barrier has now passed, and there is now high confidence about the state of ENSO during the peak of the Atlantic hurricane season. ENSO is currently cool-neutral at the moment, as weekly Niño 3.4 SSTs have been consistently below normal since mid-May, aside from a brief warm-up in late June. Climate models suggest that the anomalous cooling over the Niño 3.4 region is likely to continue, and a weak La Niña could develop at some point this fall. The latest forecast from the Climate Prediction Center estimates a 50% chance of La Niña conditions, a 47% chance of ENSO-neutral, and only a 3% chance of El Niño conditions for the August-September-October trimonthly period. La Niña events typically result in reduced vertical wind shear over the deep tropical Atlantic, making the Atlantic more favorable for hurricane activity. There is now high confidence that El Niño conditions will not be present during the peak of the season, which suggests that ENSO will be a significant enhancing factor for Atlantic hurricane activity this year.

July Atlantic basin conditions

The atmosphere already appears to be responding to the transition to cool ENSO. Anomalous sinking motion has become established over the central Pacific over the last 2-3 months, while anomalous rising motion has persisted over Africa and the Indian Ocean over the same time frame. Zonal flow at 200mb has been more easterly than normal over the Atlantic MDR and Caribbean thus far in July, while zonal flow at 850mb has been more westerly than normal. This means that vertical wind shear over the Atlantic MDR and Caribbean has been significantly weaker than normal during July – another highly favorable signal for Atlantic hurricane activity.

One, likely minor potential inhibiting factor is dry mid-level air over the Atlantic basin. During July, aside from the eastern tropical Atlantic and Gulf of Mexico, most of the tropical and subtropical Atlantic were drier than normal at 600 mb. Dry mid-level air can limit development, especially of weaker tropical cyclones battling wind shear. Regardless, with sea surface temperatures warmer than normal and wind shear weaker than normal, tropical cyclones may be more likely to overcome this potential inhibiting factor if it persists into the peak of the season. It should also be noted, though, that mid-level moisture typically reaches a minimum in the Atlantic during July.

West African Monsoon

In recent years, the West African Monsoon has been stronger than normal, leading to enhanced rainfall over the African Sahel region and stronger tropical waves. That pattern appears to have continued this year, with nearly all of the Sahel region receiving more precipitation than normal since the start of June. This has been reinforced by a strong rising motion standing wave over Africa and the Indian Ocean, leading to enhanced convection and thunderstorm activity. This is a highly favorable base state for Atlantic hurricanes. I think it is likely that the strong West African Monsoon and wet Sahel region will lead to an active “Cabo Verde” season with the potential for multiple hurricanes to form in the deep tropics east of 40°W.

Cyclonic Fury’s July 2020 Atlantic hurricane season forecast:

• 18-22 named storms (1981-2010 average: 12.07)
• 8-11 hurricanes (1981-2010 average: 6.12)
• 4-6 major (Category 3+) hurricanes (1981-2010 average: 2.63)
• Accumulated Cyclone Energy 180 (+/- 40) (1981-2010 average: 105.5)

Cyclonic Fury also gives the following probabilities of activity. Right now, our forecast gives a 85% chance activity will be above the 1981-2010 30-year average, and a 60% chance of being “hyperactive”.

• Hyperactive season: 60% (Accumulated Cyclone Energy (ACE) of 153 or greater, given the parameters of an above-normal season are also met. This is the most likely scenario, considering all of the above factors and very high activity so far during the season.)
• Above normal season: 30% (Accumulated Cyclone Energy (ACE) of 112-152, with at least two of the following three parameters met or exceeded: 13 named storms, 7 hurricanes and 3 major hurricanes. This is somewhat possible if the anomalously dry mid-levels in the tropical Atlantic damper activity slightly.)
• Near normal season: 10% (Does not fall into the Below Normal, Above Normal or Hyperactive criteria. This scenario is unlikely, and will likely only occur if the dry mid-level air significantly suppresses activity.)
• Below normal season: Near 0% (This scenario is extremely unlikely, but I prefer not to put “no chance” because saying a 0% chance in meteorology is never a good idea.)

It remains too soon to specifically say what areas are at greatest risk for the 2020 Atlantic hurricane season – but the southeastern United States needs to keep an eye on the current threat (Tropical Storm Isaias). Regardless, there have already been four tropical cyclones to make landfall in the United States in 2020, including one hurricane (Hanna). This is our final forecast for the 2020 Atlantic hurricane season.

Cyclonic Fury also considers the following four years to be the best possible analogs for the 2020 Atlantic hurricane season. It should be stressed, however, that every hurricane season is different and nobody should expect a “repeat” of any season. 

• 1995 – 19 named storms, 11 hurricanes, 5 major hurricanes
• 2005 – 28 named storms, 15 hurricanes, 7 major hurricanes
• 2010 – 19 named storms, 12 hurricanes, 5 major hurricanes
• 2017 – 17 named storms, 10 hurricanes, 6 major hurricanes
• Analog average – 20.75 named storms, 12 hurricanes, 5.75 major hurricanes

Cyclonic Fury July forecast verification

Cyclonic Fury has issued late July Atlantic hurricane season outlooks in 2018 and 2019. Our 2018 outlook significantly underestimated the activity of the season (though the major hurricane total was within the range), as we predicted 10-13 named storms, 5-7 hurricanes and 1-3 major hurricanes with an ACE of 80 +/- 20 units. Actual activity was: 15 named storms, 8 hurricanes and 2 major hurricanes, with an ACE of 129 units. Our July 2019 outlook verified somewhat better, as we predicted 12-16 named storms, 6-9 hurricanes and 2-4 major hurricanes with an ACE of 120 +/- 40 units. The hurricane, major hurricane, and ACE totals were all within our forecast ranges, though 18 named storms formed, two more than our maximum estimate of 16.