The 2020 Atlantic hurricane season officially begins on Monday, June 1, but the Atlantic has already seen one tropical storm form – Arthur. Arthur formed off the United States East Coast on May 16 and passed very close to the North Carolina Outer Banks on May 18, though overall effects were minimal. Our confidence has increased since late March that the 2020 Atlantic hurricane season will probably more active than normal, since the equatorial Pacific has cooled to below-normal levels, and there is now high confidence that El Niño will not be present this hurricane season. However, sea surface temperatures in the Atlantic’s Main Development Region are only near average, cooler than most hyperactive seasons.

Atlantic Sea Surface Temperatures

Atlantic sea surface temperature anomalies in the Atlantic, at the moment, do not strongly resemble either a positive or negative Atlantic Multidecadal Oscillation (AMO) pattern. Although the subtropical eastern Atlantic is warmer than normal, which during May is positively correlated with Atlantic hurricane activity, the Atlantic MDR has near-average sea surface temperature anomalies overall. Over the past month, the southeastern tropical Atlantic has been warmer than normal, while the central and western tropical Atlantic has been slightly cooler than normal. The far north Atlantic is cooler than normal, with is typical of a negative AMO pattern, but this feature has been persistent over the past several years and has done little to limit Atlantic hurricane activity. Over the past month, the western subtropical Atlantic has been cooler than normal, which is in contrast with most recent years. Cooler than normal sea surface temperatures in this region are actually positively correlated with Atlantic hurricane activity, since the tropics are anomalously warmer than the subtropics. Despite the Atlantic MDR only having near-average sea surface temperatures, it is still warmer overall than 2018 and 2019, both above-average Atlantic hurricane seasons. Since the Atlantic remains in a high-activity era that began in 1995, I do not expect the Atlantic sea surface temperature profile to be unfavorable enough to prevent an above-average season on its own.

El Niño Southern Oscillation (ENSO)

The equatorial Pacific has significantly cooled since our last forecast in late March. The latest weekly sea surface temperature anomaly value for the Niño 3.4 region was -0.4°C, the coldest weekly value since September 2019, and down significantly from +0.7°C in mid-April. The Niño 3.4 region exceeded the El Niño threshold for much of the winter and early spring, but a recent strengthening of the Pacific trade winds has resulted in significant cooling in both the equatorial Pacific surface and subsurface. Quite possibly the biggest challenge in early hurricane season forecasting is the Spring Predictability Barrier, when climate models struggle to predict the evolution of the El Niño-Southern Oscillation (ENSO). For August-September-October, the latest CPC/IRI ENSO forecast from Columbia University estimates a 38% chance of La Niña, a 52% chance of ENSO-neutral, and only a 10% chance of El Niño. El Niño events typically result in increased westerly vertical wind shear over the tropical Atlantic, which is unfavorable for hurricane formation. It appears likely that ENSO will be in a very favorable phase for Atlantic hurricane development during the peak of the 2020 Atlantic hurricane season. I expect ENSO to be somewhere in the cool neutral to weak La Niña range for the peak of the season, which would likely result in reduced vertical wind shear over the tropical Atlantic.

None of the models in the NMME suite predict El Niño will develop by September, and the NMME mean is very close to the La Niña threshold by September. I still am somewhat skeptical of a strong La Nina event developing, due to a recent warming of the North Pacific Meridional Mode (NPMM). This could result in a more active eastern Pacific than during a typical La Nina event, which may slightly reduce the enhancing effect of ENSO on the 2020 Atlantic hurricane season. Regardless, with ENSO likely to be in the cool neutral to weak La Niña range, I expect vertical wind shear to be reduced over the tropical Atlantic, including the Caribbean Sea. The Caribbean Sea has been quiet in recent years, with no major hurricanes developing in the region in 2018 or 2019. Considering ENSO is likely to be cooler than the last two seasons, I would say chances of a strong hurricane in the Caribbean Sea are higher than normal this year.

West African Monsoon

In recent years, the west African Monsoon has been generally stronger than normal, which has resulted in enhanced African Easterly Wave activity. In 2018 alone, despite a significantly colder than normal MDR, a very strong WAM was enough to significantly enhance hurricane activity in this region. During the past month, precipitable water has been above normal over western Africa north of 10°N. This likely foretells a strong West African Monsoon (WAM) once again this year. In addition, the Gulf of Guinea (the equatorial Atlantic south of western Africa) has anomalously cooled lately, which also favors a stronger than normal WAM.

Precipitation Forecast

The May 2020 NMME forecast for August-September-October (ASO) 2020 is currently predicting above-normal precipitation for the Atlantic MDR, Caribbean Sea, Gulf of Mexico, and the western Atlantic off the U.S. East Coast. This suggests that climate models are predicting a more favorable pattern for Atlantic hurricane activity than usual. The NMME ASO precipitation forecast looks much more favorable than it did the past two years at this time. It should be noted, however, that precipitation anomaly forecasts are not necessarily reliable predictors of hurricane tracks. This is because tropical cyclones are small-scale features that are only in a particular region over a short time scale, and the above graphic is a three-month precipitation anomaly.

Cyclonic Fury’s May 2020 Atlantic hurricane season forecast update:

• 15-19 named storms (1981-2010 average: 12.07)
• 7-10 hurricanes (1981-2010 average: 6.12)
• 3-5 major (Category 3+) hurricanes (1981-2010 average: 2.63)
• Accumulated Cyclone Energy 150 (+/- 40) (1981-2010 average: 105.5)

It is interesting to note that this is the highest Atlantic hurricane season forecast ever predicted by Cyclonic Fury, but is fairly similar – and even lower than – some expert forecasts like North Carolina State University and Penn State University.

Cyclonic Fury also gives the following probabilities of activity. Right now, our forecast gives a 70% chance activity will be above the 1981-2010 30-year average.

• Hyperactive season: 30% (Accumulated Cyclone Energy (ACE) of 153 or greater, given the parameters of an above-normal season are also met. This will likely occur if anomalous tropical Atlantic warming occurs during the next few months, and ENSO is cool neutral or weak La Nina during the peak.)
• Above normal season: 40% (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 the most likely scenario and assumes that the near-average MDR will slightly damper activity compared to the most hyperactive seasons, such as 1995, 2004, 2005 and 2017).
• Near normal season: 20% (Does not fall into the Below Normal, Above Normal or Hyperactive criteria. This scenario is somewhat less likely, but could occur if the Atlantic MDR cools further during the summer to below-normal levels.)
• Below normal season: 10% (This is an unlikely scenario, and will likely only occur if the tropical Atlantic anomalously cools significantly and stability in the tropical Atlantic or Saharan dust becomes a strong enough factor to significantly suppress activity.)

At this extended range, it is near impossible to predict which areas, if any, will have hurricane or tropical storm threats in 2020. The final Cyclonic Fury forecast for the 2020 Atlantic hurricane season will be released on July 28, 2020.

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. 

• 1996 – 13 named storms, 9 hurricanes, 6 major hurricanes
• 2003 – 16 named storms, 7 hurricanes, 3 major hurricanes
• 2007 – 15 named storms, 6 hurricanes, 2 major hurricanes
• 2010 – 19 named storms, 12 hurricanes, 5 major hurricanes
• Analog average – 15.75 named storms, 8.5 hurricanes, 4 major hurricanes

Cyclonic Fury May Forecasts Verification

This is the fourth year Cyclonic Fury has issued a May Atlantic hurricane season forecast. Our first May Atlantic hurricane season forecast was released in 2017, predicting 13 named storms, 6 hurricanes and 3 major hurricanes (excluding Tropical Storm Arlene). This forecast fell well short of the actual activity, which was 17 named storms, 10 hurricanes, and 6 major hurricanes. In May 2018, Cyclonic Fury began to use ranges as I do now, predicting 10-14 named storms, 4-7 hurricanes, 2-3 major hurricanes, and an ACE index of 90 +/- 25 units. This forecast, just like expert groups in 2018, fell well short of the actual activity of 15 named storms, 8 hurricanes, 2 major hurricanes and an ACE index of 130 units. In May 2019, Cyclonic Fury predicted 11-15 named storms, 5-8 hurricanes, and 1-3 major hurricanes, with an ACE index of 105 +/- 40 units. Once again, Atlantic hurricane activity verified higher than my forecast, as 18 named storms, 6 hurricanes, and 3 major hurricanes formed, with an ACE index of 130 units. However, I did correctly suggest that El Niño persisting was not a guarantee. While Cyclonic Fury has under-forecast the past three Atlantic hurricane seasons, the same has been true for most expert groups aside from NOAA.