Weather - Ocean Navigator

01 Sep

Cooking up a cyclone

Ocean NavigatorWeatherENSO, hurricanes, marine weather, tropical cyclone development, tropical cyclones, wind shear

As the June to November hurricane season evolves, attention will gradually focus on certain conditions of both atmosphere and ocean — six specific factors, or “ingredients.” Not only are these factors necessary, but their timing needs to be synchronized to cook up a cyclone. A number of those “ingredients” can be affected by the status of ENSO, a known, periodic, irregular (two to seven year cycle), tropical climactic seesaw of atmospheric pressure, sea surface temperature and winds. Finally, an unanticipated factor may appear that warps model predictions of a potential storm’s genesis, intensity and track – an effect sometimes dubbed…

01 Sep

Crossing the Doldrums

Ocean NavigatorOcean Voyaging, WeatherAscension Island, Barbados, Galapagos, GRIB files, Hawaii, ITCZ, Marquesas, ocean sailing, offshore sailing, The Doldrums, trade winds, Tuamotus

For centuries sailors dreaded the aptly named Doldrums. This band of windless, hot, and humid weather near the equator could stall sailing ships for weeks, driving the crew to distraction with the monotony and sometimes even leading to the onset of scurvy as fresh supplies ran out. While sailors today needn’t fear scurvy, most of us still dislike this part of the ocean. Most voyagers try to minimize time spent in the Doldrums. This strategy starts with obtaining accurate weather forecasts, whether over single-sideband radio or satellite phone connection. Even in the last 15 years that I’ve been voyaging, the…

19 Aug

Ken McKinleyNewsletter, Weather

We are now well into the 2021 hurricane season and are watching the evolution of tropical cyclones in the Atlantic and the Pacific. In the past I have used these newsletters to present some information about particularly memorable hurricanes, but this time let’s take a look at a system that, while impactful for some, has not been a historic system by any measure. This system was very slow to develop despite traveling over some rather warm ocean waters at times during the first part of its history. I will examine this system through a series of satellite images with comments…

30 Jun

Tim QueeneyWeather

On March 22, 2021, NOAA announced that the National Weather Service (NWS) would use a new global computer model for weather forecasts. This is an “under the hood” type of improvement that most voyagers won’t see directly. If the new system works as advertised, however, voyagers should see better weather forecasts on their vessels. NOAA says the new Global Forecast System (GFS) “will increase forecast capabilities across the U.S. These advancements will improve hurricane genesis forecasting, modeling for snowfall location, heavy rainfall forecasts, and overall model performance.” The GFS is a numerical weather prediction model that uses a mathematical model…

11 Jun

Capt. Wayne CanningNewsletter, Weather

From the Ocean Navigator School of Seamanship weather course A comma cloud system is really nothing more than a more descriptive name for a cyclone or low-pressure system. Learning to recognize the elements of the comma cloud will help voyagers when they’re studying satellite images and weather charts. In general, a comma cloud is a deep mass of multilayered clouds that is often shaped 1ike a comma. It reflects a region of positive vorticity advection (PVA) and can vary in size from a few hundred miles (a clump of thunderstorms whose anvils combine in the shape of a comma) to…

14 Apr

Ken McKinleyNewsletter, Weather

In the last newsletter I speculated on the possible retirement of hurricane names over the past two Atlantic hurricane seasons. Recall that it is the World Meteorological Organization (WMO) that generates the lists of names that are used for tropical cyclones around the world, and because of the Covid-19 pandemic, they had been unable to meet after the 2019 hurricane season to decide which names should be retired from the list because the storms were particularly impactful in terms of property damage and/or loss of life. The WMO committee in charge of this task finally met (virtually) in March of…

09 Feb

Ken McKinleyNewsletter, Weather

The 2020 hurricane season was one for the history books. For just the second time in modern times, the list of Atlantic storm names was exhausted, requiring the use of the Greek alphabet. The last time this happened was in 2005, which was the year of Katrina. In that year, storm names extended six deep into the Greek alphabet, with the final storm that year having the name “Zeta”. For the 2020 season, the names went all the way to Iota (the ninth letter of the Greek alphabet). The final storm advisory for the 2020 season was issued on November…

25 Aug

Planning, communication and flexibility

Ocean NavigatorWeather

Weather routers provide services to ocean voyagers for passages all around the globe. These professionals are usually degreed meteorologists who also have expertise in ocean currents, the dynamics of sea state, and local weather phenomena that occur in different areas of the world. Routers also have an understanding of the issues faced by voyagers in many different types of vessels, from large commercial ships like tankers and containerships to much smaller recreational boats. Clients can include oceangoing tugs and barges, commercial fishing vessels, megayachts, cruising and racing sailboats, trawler yachts and even human-powered craft. While the weather router will contribute…

18 May

Wave energy charts as voyage planning tools

Ocean NavigatorWeather

Pilot charts are key tools for anyone planning an offshore voyage. These charts have been developed through the analysis of weather data gathered over hundreds of years. They graphically present historical climatological data in a sensible and understandable fashion. For each of the world’s ocean basins, a series of 12 monthly charts displays information about winds, currents, wave heights, atmospheric pressure, ice sightings and more. The prudent mariner uses all means to plan a safe voyage and pilot charts provide one of these fundamental means. Recent work by a scientist in Canada has produced a thoroughly modern look at one…

01 Jan

By the numbers

Ocean NavigatorGood Reads, Weather

Long before the advent of electronics and high tech wind measuring devices, a qualitative wind estimating method called the Beaufort Scale of Wind Forces was used. It was invented by an early English navigator by the name of Francis Beaufort (1774 to 1857) who wanted to correlate ships' log reports of wind speed with the ensuing action taken by the ships' skippers to set the proper amount of sail on the square riggers. Too little sail and the ship was not combat ready; too much sail and the ship risked having its sticks blown out. His scale ranged from 1…