2020 Tropical Storm Season Outlook Mid-August Update

2020 Tropical Storm Season Outlook Mid-August Update


This report provides an update on the tropical storm season in the key basins — Atlantic, East Pacific, West Pacific, and Indian Ocean. The timing (mid-August) was chosen since it is approaching the peak of the tropical storm season which is September. For reference, Figure 1 depicts a map of the four basins and the tropical storm frequency during the past 40 years around the globe. 

Figure 01: Number of tropical storms by latitude/longitude, 1979-2019. Source: troPYcal, Everstream Analytics 

The theme of this update is consistent with the initial forecast in mid-May and the last update on July 1, 2020. Since May, the conclusion has been that the basins with the most risk of tropical activity and impacts to the supply chain are the Atlantic and the Indian Ocean. On the opposite end of the spectrum, risk and impacts on the supply chain in the other two basins — the East Pacific and West Pacific — have consistently been below normal.   

While the theme of the forecast remains consistent, the amplitude has increased. Hence, the zones of high risk (above normal activity) have trended even higher while the zones of low risk (below normal activity) have trended lower.   

Much of the focus of this report will be on the Atlantic Basin (Gulf of Mexico, Caribbean, and tropical Atlantic). This is the area that, by far, has the highest risk of significant impacts during the coming months. Businesses that have exposure within this area either directly or indirectly (ports, cargo airports, major cities, shipping lanes, and transportation hubs), need to prioritize resources and develop contingency plans in advance. What makes this situation most unique is that COVID-19 continues to be at extremely high levels in many of the vulnerable tropical areas — the southern U.S., portions of Central America, and the Caribbean. The potential for overlapping disasters is not only a possibility, but there is a high likelihood for this to occur in portions of the Atlantic Basin during the next few months.  

The intent of this report is to supplement the original report which was issued in the middle of May 2020. Many of the basic concepts that were introduced in that report, such as the climatology of the seasons, accumulated cyclone energy (ACE), historical risk to global ports, cities, and airports, are not covered but can be found in the earlier report. Part 1 of this report outlines the season thus far and highlights a few of the most impactful storms as well as their impact on supply chains. Part 2 examines the changes, if any, of the drivers of tropical activity, both oceanic and atmospheric. Finally, Part 3 will provide an update to the forecast as the peak of the season looms in September. 

The Season So Far  

The vast majority of the tropical season is still ahead. In the Atlantic Basin by August 15, 12 percent of the season is traditionally complete which means 88 percent of the season remains. Figure 2 depicts the climatology of hurricane and tropical storms in the Atlantic Basin. The peak of the season, the time frame that statistically is the likeliest for tropical storm formation, is September 10. The other basins have a similar story with between 10 and 15 percent of the season having been completed so far.   

Figure 02: Number of tropical storms and hurricanes per 100 years from 
May 1 – December 31. Source: NOAA 

The following sections will examine the start of the season in each of the four key basins. First, the Atlantic basin, which comprises the Gulf of Mexico, Caribbean, and Atlantic, is analyzed.   

The Atlantic 

Figure 03: Accumulated Cyclone Energy through August 15 in the Atlantic basin, 1979-2020. Source: Everstream Analytics, HURDAT 

The graph below depicts the amount of tropical activity in terms of ACE (Accumulated Cyclone Energy) in the Atlantic Basin through August 15 for each year from 1979 to 2020. As a refresher, ACE is a metric used to quantify tropical activity and brings into account not only the number of storms, but the duration and intensity of storms. The normal amount of ACE for the period until August 15 is 13. This year, ACE is approximately double the normal at 24. As a matter of fact, this season has recorded the 6th fastest start since 1979 with the top 5 years being 2005, 1980, 2008, 1995, and 2004. Later in this report, the obvious question will be addressed – does a fast start to the season correlate to the rest of the season being active?    

Figure 4 shows the storm tracks in the Atlantic as of August 15. There have been 11 named storms, 2 of which became hurricanes — Hanna and Isaias. The most impactful storm was Isaias which tracked up the East Coast of the U.S.      

Figure 04: Summary of Atlantic tropical cyclone tracks through August 15, 2020. Source: troPYcal, Everstream Analytics 
Hurricane Isaias 
Although Isaias received only a Category-1 rating on the five-tier Saffir-Simpson hurricane wind scale, the storm demonstrated an outsized disruptive impact to supply chains due to its direct path along the majority of the industrialized eastern United States coastline. On July 28, Isaias first developed into a storm producing gale-force winds of 40 mph (64.3 km/h) with gusts of 52 mph (83.7 km/h). Tropical storm warnings were issued for Puerto Rico, the U.S. Virgin Islands, Antigua, Barbuda, the British Virgin Islands, Montserrat, St. Kitts and Nevis, Guadeloupe, Martinique, Saint Martin, Saba, and Sint Eustatius. Within the Caribbean, disruptions to supply chains were most pronounced in Puerto Rico, a key manufacturing hub for pharmaceuticals. Power outages were experienced by 432,000 customers in Puerto Rico, leading to the resignation of the CEO of the Electric Power Authority (PREPA), the operator of the outdated power grid.
By late on July 30, the tropical storm developed into a Category-1 hurricane with maximum sustained winds of 80 mph (129 km/h) as it proceeded towards the central and southeastern Bahamas. As the forecasted storm path shifted away from coastal Florida but closer to a large portion of the Atlantic coastline, the United States Coast Guard began to order a larger number of ports to take precautionary measures. Ultimately, measures that disrupted or halted operations were recorded at commercial ports in Puerto Rico, the Florida Atlantic coast, Georgia, South Carolina, North Carolina, Virginia, Delaware, Maryland, Pennsylvania, and New Jersey. In addition to damages from sustained gale-force winds and heavy rain, Isaias generated significant tornado activity, most notably in North Carolina on August 3, where 14 tornados were recorded. Overall, private insurers estimate wind and storm surge losses (therefore excluding flood damage covered under the National Flood Insurance Program) of USD 4 billion (EUR 3.4 billion) in the United States and USD 200 million (EUR 170 million) in insured losses in the Caribbean as a result of the storm.
The most heavily-impacted region was the tristate area of New York, New Jersey, and Connecticut, where Hurricane Isaias brought the highest sustained wind speeds since the devastating Hurricane Sandy in 2012. Although the New York City area in particular has invested USD 3.5 billion (EUR 2.96 billion) in storm surge protection following Hurricane Sandy, its power remains vulnerable to outages from high-wind events and was slow to recover. In total, an estimated 6.4 million customers from South Carolina to Maine experienced power outages; approximately 3.7 million of those customers were in the tristate area, where widespread outages exceeding 48 hours were recorded. 

The East Pacific 

Tropical activity in the eastern Pacific is running below normal so far this season. Figure 5 portrays the ACE values in this area as of August 15. During the past 41 years, this year’s value is the 6th lowest.   

The most impactful storm so far was Tropical Storm Amanda which made landfall in Guatemala in late May. This was a short-lived but devastating storm for portions of Central America as widespread flooding occurred once the storm moved inland. After moving across Central America, the storm reformed and became Tropical Storm Cristobal in the Gulf of Mexico. 

Figure 05: Accumulated Cyclone Energy through August 15 in the East Pacific basin, 1979-2020. Source: Everstream Analytics, IBTrACS 
Tropical Storm Amanda
Tropical Storm Amanda was the first named storm of the 2020 East Pacific season. It formulated off the coast of Guatemala, moving inland from the southeast corner of the country. Once inland, it weakened over the mountainous terrain, approximately 100 miles (161 km) northeast of Guatemala City. The remnants of the storm generated heavy rainfall over Central America, with the most damage being concentrated in El Salvador. Official estimates put the total damage inflicted by Tropical Storm Amanda at USD 200 million (EUR 168.04 million) with roughly 150,000 people directly impacted. 
The government of El Salvador declared a 15-day state of emergency. The official post-storm damage report confirmed that there were 57 major floods; 1,114 landslides; 28 damaged bridges; and four collapsed bridges across the country. El Salvador’s average annual rainfall is about 72 inches. 25 percent of that fell within the 70-hour duration of Tropical Storm Amanda. Most reports estimated between 500 to 800 millimeters of rainfall in El Salvador, with similar reports in Guatemala. 10 of El Salvador’s 14 regional departments declared severe flood emergencies. The Acelhuate River in San Salvador, the Comapa River in San Luis La Herradura, and El Piro stream in in La Cuchilla had become swollen, overflowing into surrounding communities.
Both countries have mountainous topographies, high soil humidity, and adjacency to the volcanic strip. This combination of factors leads to slope vulnerabilities, which in this case resulted in frequent mudslides, rockslides, and landslides following the storm’s flooding. This considerably disrupted the ease of ground transportation in El Salvador for the two weeks following the tropical storm. In addition to displaced terrain, including fallen trees, there was widespread structural collapse due to the country’s poor-quality infrastructure. Building debris blocked the roadways and prevented the connectivity of different municipalities. This was reported and confirmed in the Aguilares municipality, an agriculture center of production which relies on ground transportation for the export of high-value cash crops of coffee and sugarcane. Access roadways to the municipalities of Bolivar and Cantón Las Tunas were reported as blocked by fallen trees. Six bridges located in the municipality La Libertad were either damaged or destroyed. 23 vehicles were swallowed by sink holes in the capital of San Salvador. These conditions rendered ground travel, including that of freight transportation, impossible in many areas of the country.
Tropical Storm Amanda had reverberating impacts that went beyond domestic disruptions. The Salvadoran Customs Directorate temporarily closed the La Hachadura border with Guatemala, the main customs point for merchandise passing between the two countries. On May 30, an orange alert was issued at the El Salvador International Airport (SAL), the Port of Acajutla (SV AQJ), and the Port of San Salvador (SV SAL). On May 31, the warning was escalated to a red alert and was established nationwide, exacerbating the existing congestion and delays due to COVID-19 closures and regulations. The Port of Acajutla, for example, was already backlogged after three months of part-time operations and personnel limitations imposed by biosecurity regulations. There are cargo disruptions from the storm that still remain. Enhanced inspection protocols for crop pest detection were implemented at ports that experienced heavy flooding during the tropical storm. The flooding created a breeding ground for a flying locust outbreak, which has been confirmed in the grasslands and cornfields of Tecoluca, El Salvador, as recent as July. Beside causing further port congestion, the onset of this pest has disabled the production of important cash crops such as corn, sugarcane, and bananas, most of which had already suffered significant damage during the storm itself.
Damage to grain crops is estimated at USD 5.5 million (EUR 4.6 million) and damage to the industrial agricultural sector at USD 21.9 million (EUR 18.4 million). A total of 56,000 hectares of crops have been damaged or destroyed by the storm. The World Food Programme (WFP) estimates more than 138,000 acres of maize, rice, and beans were flooded, with additional losses in vegetable production. 

The West Pacific 

In stark contrast to the Atlantic, the start of this season in the western Pacific has been very quiet. Figure 6 depicts the ACE values for every year since 1979 for the period until August 15. This year is the second lowest on record and only slightly higher than the lowest year — 1998.  Normally by this time in August, the West Pacific ACE value is 91 though this year, it is 13. Hence, it is one of the most inactive starts to the typhoon season ever recorded in the western Pacific.   

Figure 06: Accumulated Cyclone Energy through August 15 in the West Pacific basin, 1979-2020. Source: Everstream Analytics, IBTrACS 

The Indian Ocean 

Unlike the Pacific, which has had a quiet, early tropical season, the start of the season in the Indian Ocean has been active with above normal activity. Figure 7 depicts the ACE values in the Indian Ocean through August 15. This year has registered in the top 10 most active years and well over twice the normal. The bulk of the high ACE values came from 2 storms — Amphan in mid-May and Nisarga in early June. Impacts from Super Cyclone Amphan, which was one of the strongest cyclones to ever develop in the Indian Ocean, are outlined below.

Figure 07: Accumulated Cyclone Energy through August 15 in the Indian Ocean basin, 1979-2020. Source: Everstream Analytics, IBTrACS
Super Cyclone Amphan 
Super Cyclonic Storm Amphan, the equivalent of a Category 5 hurricane on the five-tier Saffir-Simpson hurricane wind scale, brought widespread damages to eastern India and southeastern Bangladesh in May 2020. The cyclone was reportedly the biggest cyclonic storm that developed over the Bay of Bengal in the last two decades after it reached a 3-minute sustained wind speed of 150 mph (240 km/h), and 1-minute sustained wind speed of 160 mph (260 km/h) on May 18. In anticipation of the landfall, authorities in West Bengal evacuated 200,000 people from low-lying areas, while officials in India evacuated around 1.2 million people from low-lying areas in 12 districts across Eastern Odisha. The storm made landfall in West Bengal on May 20, with sustained wind speeds of 100 mph (155 km/h), dissipating shortly after. In total, estimated damages amounted to over USD 13 billion (EUR 10.9 billion) in West Bengal alone.
As India and Bangladesh were still in the midst of struggling with the impacts of the COVID-19 pandemic, significant challenges and disruptions to manufacturing and logistics operations were anticipated due to the storm’s landfall. In particular in India, winds, and surges caused by Storm Amphan disrupted port and airport operations for a number of days. India’s fifth busiest airport nationwide which serves the Kolkata metropolitan area shut down its operations for 24 hours due to the storm. Likewise, ports in the path of the storm stopped the movement of incoming and outgoing container vessels for 24-36 hours to prevent damage, including the Port of Kolkata and the Port of Paradip.
In Bangladesh, port authorities at the Port of Chattogram (Chittagong) — Bangladesh’s key port that handles nearly 80 percent of the country’s total export-import activities — issued severe cyclone warnings and sent vessels anchored at the ports to outer anchorage for safe harbor. The port suspended all landside cargo activities for 36 hours, while port handling equipment was moved to safer places.
The super cyclone came at a time when the ports in India and Bangladesh were already facing congestion for several weeks due to COVID-19 related restrictions. This posed additional challenges to ocean freight dependent international supply chains in and out of the affected regions amid an economic restart following the easing of COVID-19 related lockdown measures.
On the manufacturing side, Storm Amphan impacted production activities in the Greater Kolkata area, causing power outages, flooding, and damages to plant infrastructure. Operations at businesses reliant on water supply were disrupted, such as Indian Oil Corporation refineries and 100 other industrial units with heavy machinery dependent on water for smooth running. Furthermore, flooded roads and closed ports in the cyclone-affected areas caused logistic difficulties, specifically for businesses such as Tata Steel’s plant in Jamshedpur, which usually relies on the port of Paradip for export activities.

All in all, the tropical season has started out as expected. The Atlantic and Indian Ocean have had a robust start while the Pacific (both eastern and western basins) has had an inactive or quiet start. What this tells us about the remainder of the season will be examined next. 

Active Start, Active Finish?

The start of this season in the Atlantic has been highly active. Does this tell us anything about the remainder of the season? Figure 8 portrays the ACE value as of August 15 and the final ACE for the season. The start of this year is the 6th highest since 1979. The 5 highest ACE years prior to August 15 was 2005, 1980, 2008, 1995, and 2004. Of these 5 similar years, 2 ended up with well above normal seasonal ACE values (1980 and 2008) while the other 3 were the 3 highest years of tropical activity — 2005, 1995, and 2004.  

Figure 08: Accumulated Cyclone Energy (ACE) through August 15 (blue) and ACE from August 16 – December 31 (red) in the Atlantic basin, 1979-2020. Source: Everstream Analytics, HURDAT

In the western Pacific, the opposite is true. This season has been one of the most inactive of the past 4 decades. Specifically, it is the second least active year in the historical record. Of the 4 years that had the slowest start (1998, 2010, 1995, and 1983), all of these years had below normal seasonal activity.  

So, how a season starts does in fact give an indication of how active or inactive the entire season will be. Much of this has to do with the underlying base state that is in place in a particular region during a season. If conditions are favorable for tropical activity at the onset of the season, it normally tends to remain in this general direction. 

Statistically, an active start to the season correlates to the entire season being active. The next section examines the physical characteristics that are driving tropical activity and determine what has, or has not, changed since the initial outlook.  

Have the Variables Changed?

As discussed in the initial tropical storm report published in May 2020, whether a season is inactive or active is largely determined by a combination of oceanic and atmospheric conditions. The role of the oceans is crucial as tropical systems get energy “locally” from the waters they travel over. The warmer sea surface temperatures (SSTs) are, the more energy tropical storms have to develop and strengthen.  

Equally as important are the atmospheric conditions during a season or periods within a season. Active seasons tend to feature lower vertical wind shear (lighter winds from the surface into the upper atmosphere) and this causes less disruption for storm formation and storm strengthening.  Stronger wind shear tends to “rip” storms apart and limits the ability for storms to form and gain strength. The jet stream pattern, i.e. whether a ridge of high pressure or a trough of low pressure is in place in a particular area, is also important in determining if conditions are favorable or unfavorable for storm formation and intensification.

Simply put, there have been no fundamental changes in the variables that have, and will continue, to influence tropical activity in the various basins.  

Sea Surface Temperatures (SSTs)

Global ocean temperatures remain at unusually high levels in most areas of the globe. Figure 9 shows the sea surface temperature (SST) anomalies as of August 10. Most tropical areas have well above normal SSTs. The one exception is the central and eastern sections of the equatorial Pacific where a weak La Niña event (defined as a period of cooler than normal SSTs in the central and eastern equatorial Pacific) is in place. The La Niña event impacts the atmospheric portion of the tropical equation as it provides favorable conditions for tropical formation and intensification in the Atlantic, while it suppresses activity in the Pacific — both east and west. 

Figure 09: Global sea surface temperature (SST) anomalies as of August 10. Source: Everstream Analytics, NCEP 

In the Atlantic, SSTs are mainly in the warmer than normal category in the key zones of formation —  the MDR (Main Development Region), Gulf of Mexico, and the Caribbean. Figures 10 through 12 show the daily SST anomalies in these sections of the Atlantic. Suffice it to say, the ocean warmth in the Atlantic is at levels that support enhanced tropical activity as the heart of the season approaches. 

Figure 10: Atlantic sea surface temperature (SST) anomalies May 12, 2020 – August 10, 2020. 
Source: Everstream Analytics, NCEP 
Figure 11: Gulf of Mexico sea surface temperature (SST) anomalies May 12, 2020 – August 10, 2020. 
Source: Everstream Analytics, NCEP 
Figure 12: The Caribbean sea surface temperature (SST) anomalies May 12, 2020 – August 10, 2020.
Source: Everstream Analytics, NCEP 

The Atmospheric Component

The atmospheric component this season will be dominated by the La Niña event across the central and eastern sections of the equatorial Pacific. In the initial tropical storm report published in May 2020, there was in-depth discussion of how and why conditions in the equatorial Pacific impact storm formation and intensification in the various tropical basins.  

The base-state of the tropics this season is La Niña, which enhances tropical activity in the Atlantic while it is a suppressor in the Pacific. The jet stream that forms because of the La Niña episode produces low wind shear in the Atlantic and high wind shear in the Pacific. The impact of this has already influenced the numbers with a well above normal start to the season in the Atlantic while the Pacific has been well below normal. With the La Niña event solidly in place, the trends of enhanced (Atlantic) and suppressed (Pacific) activity shows all signs of continuing into the heart of the season. 

The 2020 Forecast – An Update 

Atlantic – Increased Risk 

  • Warm SSTs
  • La Niña event = reduced wind shear

The Atlantic Basin continues to have the highest risk of any ocean basin due to the combination of favorable ocean temperatures (warm SSTs) and atmospheric conditions (lower wind shear due to La Niña event). Already, it has been one of the most active starts to the Atlantic tropical season in the past four decades. Historically, the active start has been a signal for a well above normal remainder of the season. In fact, we are now forecasting a well above normal ACE value for the season at 175-200. This is up from the 125-150 ACE in our initial report and would rank as a top 5 most active of the past 40 years. Figure 13 below shows the forecast for the upcoming season.

Figure 13: Atlantic ACE Forecast 2020. Source: Everstream Analytics 

Additionally, the period from late August through the first half of September looks to be the next window when a flurry of tropical activity is likely. In other words, we are seeing signals for frequent storm development, some of which could become intense, with multiple storms in the basin at the same time. This potential hyperactive mode corresponds to the peak of the tropical season in early September and could result in multiple supply chain threats.

While the details of the upcoming flurry of activity do not tell us anything about individual storms and how they may impact specific supply chain networks, business operations, and economic sectors, such details will be addressed by the Everstream Analytics team on a day-to-day and week-to-week basis for the remainder of this tropical storm season. 

West Pacific and East Pacific – Decreased Risk

  • Variable SSTs
  • La Niña event = increased wind shear

Both the West Pacific and East Pacific Basins continue to have decreased risk and thus below normal tropical activity and ACE. This is due to the combination of the more variable water temperatures across the Pacific Ocean and La Niña induced wind shear which reduces the odds of activity this season. This season so far in both the West Pacific and East Pacific has started on the inactive side. Moreover, an inactive or quieter season implies lower overall risk but it does not imply that an individual storm still cannot cause major disruptions for supply chains if it impacts a vulnerable area. 

Indian Ocean – Equal Risk 

  • Warm SSTs
  • La Niña event = mixed

Following the Atlantic Basin, the Indian Ocean basin is the second highest risk zone. Overall, the signals remain mixed as Indian Ocean SSTs remain abnormally warm but wind shear is variable. When analyzing the season thus far and combining this with the indicators, our forecast for the Indian Ocean continues to call for near-normal to slightly above normal tropical activity during the remainder of the season. 

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