The COVID-19 Coronavirus has the entire world in crisis mode. The United States now has more cases than any other country, and many are calling it the epicenter of the outbreak. A graduate school colleague, Kevin Jones, sent me a direct message recently asking what I thought about the possible intersection of COVID-19 and the upcoming Atlantic hurricane season. My immediate response to him was that I hoped that there was no significant intersection. Herein, I offer some more specific thoughts based on the climatology of the hurricane season.
Hurricane Michael (2018)
I should note that experts at Colorado State University and NOAA have not issued their seasonal forecasts for the 2020 season. I consider these institutions to be very credible sources for seasonal hurricane outlooks. According to the Colorado State University Tropical Meteorology Project website, the first seasonal forecast will be issued on April 2nd. However, Dr. Phil Klotzbach, the program director and a tropical meteorology expert, tweeted the graphic below with the following statement last week:
The latest #ElNino model prediction plume has the majority of models predicting ENSO-neutral conditions for peak Atlantic #hurricane season (August-October). Very few models call for #ElNino. El Nino typically reduces Atlantic hurricane activity via increased wind shear.
March predictions for El Nino
As Dr. Klotzbach noted, El Nino tends to reduce hurricane activity because of increased wind shear (change in wind speed and/or direction in the atmosphere). If you are reading the tea leaves, this would suggest that a “neutral” year might lead to normal t0 above-average hurricane activity in the Atlantic Basin this season. According to NOAA’s website, “On average, the Atlantic hurricane season produces 12 named storms, of which six become hurricanes, including three major hurricanes.” At this point, I should remind readers that researchers at Penn State University recently confirmed something that many of us in meteorology have long understood - weather prediction models are limited beyond 10 to 14 days so there is not much guidance from them in March. Seasonal hurricane forecasting is based on a variety of factors in addition to El Nino. They include West African rainfall, wind shear, atmospheric temperature anomalies, and other factors. Seasonal hurricane forecasts can be quite useful for business and policy planning, but a devastating hurricane can happen in any season irrespective of the long-range prediction.
Ok, let's get back to Kevin’s original question. My initial response to him was tempered by a well-known attribute of the Atlantic hurricane season. The peak of the season tends to be in the early weeks of September. Mid-August to mid-October is when we can expect roughly 74% of tropical storm days, 87% of category 1-2 hurricane days, and approximately 95% of category 3-5 (major) hurricane days in the Atlantic hurricane season. Though the season actually “starts” on June 1st, water temperatures and atmospheric shear conditions are generally more favorable later in the season. Water has a larger specific heat than land. Specific heat is simply the amount of heat for some given unit mass that is required to increase temperature by 1 degree C. In other words, it takes water longer to heat up than dry soil or sand. This is why a walk on the beach in May might warm your feet even as the water is cold. The specific heat of the water and ocean mixing also explains much of the graphic below.
Peak of the Atlantic hurricane season is in September
COVID-19 Coronavirus is raging at the time of writing, but I am hopeful that it will start to wane in the coming weeks to months. If so, there would likely not be much of an overlap between the peak of this pandemic and even the start of the hurricane season (June). The pace and evolution of the pandemic are certainly unpredictable at this point so any statements that I am making are somewhat speculative. Of more immediate relevancy, Washington Post’s Capital Weather Gang recently reported on concerns about severe weather shelters and COVID-19 as much of the country transitions to severe weather season. The consensus of officials was that, if needed, citizens should go to tornado shelters even in the midst of the coronavirus crisis.
The COVID-19 pandemic is very similar to hurricane season in some ways. Hurricane warnings are often downplayed or ignored in the same way that I am observing with messaging about social distancing. Federal, state, and local resources are fully engaged with COVID-19. A Hurricane Michael or Harvey scale event would like be a debilitating event if the COVID-19 situation has not improved. Even if improvement happens, the fallout from COVID-19 in the healthcare, first responder, economic and emergency management communities will remain. From that standpoint, I am very concerned about what happens this hurricane season. Brian McNoldy is a hurricane expert at the University of Miami who has also followed COVID-19 closely. He gets the last word below.
The active part of hurricane season usually begins in August, so we have 4 months for the pandemic to slow down and be able to focus on a different natural hazard. Part of hurricane season preparation is buying supplies similar to what we're currently doing, and many people here in south Florida already have a checklist to prepare for being self-sufficient for a week or so. At least with the pandemic prep, we don't have to worry about water and gas stockpiles and losing electricity and internet access! For most of the country's population, hurricane season isn't personal. But for hurricane-prone areas along the Gulf coast, southeast and mid-Atlantic states, we will prepare just the same... we just have a little head-start now.
