Sea Science: by Jordanna Sheermohamed
Weather conditions are generally what determine “yachting season” in various destinations around the world. Most voyages are seeking moderately warm breezes, long days and pleasant waters. Other factors – such as cultural events, boat shows, and festivals – may play into chosen routes, but the weather is the general dictator on the scene.
Global pressure patterns determine where and how wind patterns work, which ultimately control the associated wave heights and relative positioning of ocean currents. Similar to the admonition “work smarter, not harder,” yachts would do well to “work with the elements, not against!” Riding with the currents can save on fuel and ensure a speedier ride. It’s no coincidence that many global routes follow the natural flow of the water.
Another major factor is precipitation patterns, as regional monsoon seasons can make for an extended wet ride. A seasonal wind pattern shift, such as ENSO (El Niño Southern Oscillation), is defined as a longitudinal shift in pressure patterns and winds that occurs, on average, every two to seven years.
In the warm phase of ENSO, El Niño, easterly winds weaken or reverse. This causes the warmer waters to shift from the Western/Central Pacific towards the Eastern Pacific, piling up along the South American coast. The warmer waters instigate thunderstorm development, so in turn, higher precipitation occurs. Another side effect of the excess water is that it reduces upwelling, which is the ability of the deeper, colder, more nutrient-rich water to make its way to the surface. Ocean currents are related to water temperatures, so this shift alters the local currents.
Conversely, during the cool phase of ENSO, La Niña, the exact opposite occurs: The easterly winds strengthen, which piles the warmer waters towards the West Pacific. This migration of water from the East to the West makes it easier for upwelling to occur along South America. The repositioned warmer waters over the West Pacific increase thunderstorm activity, and therefore precipitation potential.
A close look at popular global destinations reveals that prime yachting season aligns with the best weather that each location has to offer.
The earliest and latest months of peak seasons tend to be the most financially affordable, as they occur while seasons are still transitioning between undesirable winds/rain/temperatures and the preferred conditions. While the weather can still be somewhat iffy, this is generally when dock space, berths and anchorages are plentiful and tourists are minimal.
Of course, some locations are blessed with a year-round yachting season, such as Florida, the Caribbean, maritime Southeast Asia or generally any place near the equator. Approximately 12 hours of daylight bless the equatorial regions, with the hours decreasing as you head north or south of this line. While that ideally works for most of the year, there is a caveat: Excessive heat in this region produces or strengthens tropical cyclones. Rapid intensification or a change in track may force a yacht to redirect its route with minimal notice, or scurry towards an available hurricane hole.
Predicting and tracking the development and movement of tropical cyclones can be very tricky. It involves a working knowledge of a four-dimensional science: How things are changing (1) from east to west; (2) from north to south; (3) from the surface of the earth throughout the atmospheric column; and (4) with time. Recent activity surrounding Hurricane Harvey was a prime example of how a tropical system can intensify in a very short amount of time, as it went from a Category 1 [74-95 mph] to minimum Category 4 [130-156mph] in less than 24 hours.
The open ocean is a nautical playground where weather writes the rules. Heeding its patterns is crucial in making the best of your adventure and your time!
Jordanna Sheermohamed is president and lead meteorologist of Weather Forecast Solutions, a private weather-forecasting company ( www.WeatherForecastSolutions.com). Comments are welcome below.