The Atlantic storm season has intensified sharply, according to updates released on September 6, 2020, with forecasters tracking multiple active tropical systems simultaneously, coastal communities preparing for potential landfalls, and emergency management agencies at national and regional levels activating the operational arrangements that the weeks ahead are likely to demand. Updated seasonal outlooks issued by the world's principal tropical meteorology centres describe a season that has already exceeded expectations and that shows every indication of continuing to produce above-average activity through the peak months of the Atlantic cyclone season.

The specific figures in the updates underscore the scale of what is being observed and projected. The number of named storms so far this season is running well above the climatological average for the date, and the rate at which new systems have been forming in recent weeks has been particularly striking. Several systems have undergone rapid intensification — a process in which a storm's maximum sustained winds increase by at least 55 kilometres per hour within 24 hours — and the frequency of rapid intensification events is running above long-term averages. Together, these indicators describe a season whose character has been established and whose principal implications for communities along the Atlantic basin are becoming increasingly clear.

What the Updated Outlooks Say

Updated seasonal outlooks from major international and national meteorological centres converge on a picture of a season likely to produce substantially more activity than the long-term average. Total named storms are projected to run significantly above climatological norms, with the number of hurricanes, major hurricanes, and cumulative measures of storm activity such as accumulated cyclone energy all projected at elevated levels. The precise numerical projections vary modestly across different forecasting organisations, reflecting the different methodologies and data inputs used, but the overall direction and magnitude of the projections are consistent.

Several factors have contributed to the conditions favourable for elevated storm activity this season. Sea surface temperatures across the main development region — the band of tropical Atlantic where a significant share of the basin's most intense storms form and develop — have been running well above average throughout the season. Atmospheric conditions have generally been conducive to storm development, with relatively weak vertical wind shear and specific large-scale patterns that have supported the formation and maintenance of tropical systems. And the broader climate context — including the current phase of the El Niño–Southern Oscillation and specific multi-decadal patterns in Atlantic sea surface temperatures — has also been aligned with elevated activity.

These factors are not independent, and specific interactions among them produce a more conducive overall environment than any single factor would suggest. Forecasters have been explicit that while individual storms remain difficult to predict far in advance, the aggregate behaviour of the season is characterised well by the combined picture that the various indicators provide.

Coastal Communities Prepare

For coastal communities along the Atlantic and Gulf coasts, the updated outlooks reinforce messages that emergency management authorities have been communicating throughout the season. Preparedness — at the household, community, business, and institutional levels — is the single most important factor determining how a given community will fare when a significant storm approaches. Specific recommendations have been consistent and have been repeated with renewed emphasis as the peak of the season approaches.

Households are encouraged to complete the specific preparations that experience has shown to make the difference between a manageable storm experience and a more difficult one. These include ensuring that emergency supplies are assembled and current, that family communication and evacuation plans are in place, that important documents are secured in ways that will survive flooding and wind damage, that home-hardening measures where feasible have been completed, and that specific preparations — such as the fuelling of vehicles, the clearing of yards, and the identification of specific evacuation destinations — are made in advance rather than during the rush of an approaching storm.

Businesses in storm-exposed regions are completing their own preparations, including continuity planning, staff communication arrangements, the securing of physical property, and specific arrangements with customers and suppliers to manage the disruptions that storms can produce. Insurance coverage reviews have been specifically recommended, with particular attention to the distinction between wind coverage, flood coverage, and specific exclusions that can produce difficult surprises after an event. Commercial property owners and operators of critical facilities have been conducting pre-season exercises and, in specific cases, investing in additional preparedness measures.

Public institutions — schools, hospitals, utilities, transport operators, and specific emergency services — have been reviewing and exercising their own preparedness arrangements. The cumulative effect of these preparations is significant, and the difference between communities that have invested consistently in preparedness and those that have not has historically been a major determinant of storm outcomes.

The Climate Context

The elevated activity being observed and projected for the current season is consistent with the broader trends in Atlantic tropical cyclone behaviour that climate scientists have been documenting for years. A warmer Atlantic produces more energy available for storms. A moister atmosphere carries more potential for heavy rainfall associated with tropical systems. Rising sea levels, while a slow process in absolute terms, amplify the impact of storm surge by allowing it to reach further inland than previously. And specific atmospheric circulation patterns, influenced in complex ways by the broader warming trend, shape the specific tracks and behaviours of individual storms.

Researchers have been careful to distinguish between statements that can be made with high confidence — that warmer sea surface temperatures tend to produce more intense storms, for example, and that a warmer atmosphere produces heavier rainfall — and statements whose supporting evidence is less definitive, such as specific claims about trends in the overall frequency of Atlantic tropical cyclones. The scientific literature on tropical cyclone climatology continues to develop, and specific aspects of the relationship between climate change and Atlantic storm behaviour remain active areas of research.

What the research does establish with increasing confidence is that the impacts of individual storms — in terms of the destruction produced by their winds, the extent of flooding from their rainfall, and the reach of their storm surge — have been trending upward in ways that are consistent with broader climate change. Formal attribution studies of specific recent storms have routinely found that the events would have been less intense, less destructive, or both in the absence of human-caused climate change.

Specific Systems of Concern

The active systems being tracked at the time of today's updates include several that warrant specific attention. Storms in various stages of development — from tropical depressions through tropical storms and hurricanes — are being monitored across the Atlantic basin. Specific forecasts for each system are being updated on established schedules, with more frequent updates as systems approach potential landfall or as their characteristics change rapidly.

For each system, the key uncertainties in the forecast concern specific aspects of the track, the intensity, and the timing of any potential landfall. Ensemble forecasting techniques, which run many different simulations of each system's possible future behaviour, provide the basis for probabilistic statements about the likely range of outcomes. The cone of uncertainty that accompanies official track forecasts reflects the historical accuracy of forecasts at various time horizons and should be interpreted as a probabilistic envelope rather than as a definitive prediction.

Residents in areas under watch or warning for any specific system are urged to follow official communications closely, to make preparations commensurate with the level of risk indicated, and to follow any evacuation orders that are issued by local authorities. The specific arrangements for evacuation, for sheltering in place, and for re-entry after an event have been communicated through local emergency management channels, and residents are encouraged to review those arrangements in advance.

The Role of Forecasting and Communication

Today's updates reflect the maturity of the operational tropical meteorology community, which has been refining its methodologies, tools, and communication practices over many decades. Forecast accuracy has improved substantially over that period, with the average error of five-day track forecasts today roughly equivalent to the error of three-day forecasts two decades ago. Intensity forecasting remains more challenging, though meaningful progress has been made and specific operational products now support better communication of intensity uncertainty.

The communication side of tropical cyclone forecasting has received particular attention in recent years. The specific ways in which forecasts are presented to the public — the graphics used, the terminology employed, the emphasis placed on different aspects of a storm's potential impact — can substantially affect how well warnings are understood and acted upon. Research on risk communication has informed specific improvements in the products issued by operational forecasting centres, and those improvements have been visible in the materials being distributed for the current season.

Specific issues — including the way that wind hazard, storm surge hazard, and rainfall-related flooding hazard are communicated separately; the treatment of uncertainty; and the communication of risk to specific populations who may not be fully served by mainstream channels — continue to be subjects of active work. Partnerships with media organisations, with social media platforms, and with community-based organisations have been important in extending the reach and effectiveness of official communication.

Emergency Management Under Pandemic Conditions

One distinctive feature of the current season has been the additional complexity introduced by the continuing public health context. Shelter operations, which typically bring displaced residents together in congregate settings, have had to be adapted to reduce the risk of respiratory disease transmission. Specific arrangements — including non-congregate sheltering in hotels, expanded shelter capacity to allow greater spacing, and specific public health protocols for shelter operations — have been developed and are being tested in practice as the season progresses.

Evacuations themselves pose specific complications in the current environment. The specific arrangements for safe mass transportation, for meal provision during evacuations, and for the return of evacuees to their homes after storms have all required additional planning. Emergency management agencies have been working with public health authorities to develop protocols that maintain the life-safety benefits of evacuations while managing the additional health considerations that the pandemic has introduced.

Health system preparedness for storm-related injuries and illnesses has had to account for the fact that health systems in many parts of the storm-exposed region have been operating under significant existing pressure. Specific plans for surge capacity, for maintaining care of non-storm-related patients during events, and for ensuring that critical health infrastructure is protected from storm damage have been refined.

Looking Ahead

The peak weeks of the Atlantic storm season are immediately ahead, and the updated outlooks released today reinforce the case for vigilance, preparedness, and coordination. Specific systems being tracked at the time of the updates will continue to evolve, and additional systems are likely to form in the weeks to come. Each will be monitored closely, forecast with the best available tools, and communicated to the public with the goal of supporting informed decisions about preparation and response.

For affected communities, the specific priority is to convert the information provided by forecasters into action on the ground. Preparations completed in advance of an approaching system produce better outcomes than preparations attempted in haste as a storm nears. Attention to official communications, cooperation with evacuation orders, and specific individual and community-level preparations are the elements that, cumulatively, make the difference between a difficult season and a catastrophic one.

For the broader system — meteorological, emergency management, public health, infrastructure, insurance, and political — the season is a continuing test of capabilities and of commitments. Each system produces lessons that feed into future preparedness. Each event illuminates strengths and weaknesses in the overall approach. And each season, taken as a whole, contributes to the long-term evolution of how the region plans for, responds to, and lives with the reality of Atlantic tropical cyclones.

Today's updates are an invitation to take that reality seriously, to act on the information available, and to approach the coming weeks with the combination of readiness, resilience, and sustained attention that the season requires. Storms will come. What can be controlled is not whether they arrive, but how well prepared communities are when they do.