Mariner’s Tropical Cyclone Guide

NOAA has put together an incredible free resource for mariners with everything you need to know about tropical cyclones.

If you haven’t seen it yet, you should definitely grab a copy of NOAA’s Mariner’s Tropical Cyclone Guide, a free PDF download. Inside you’ll find countless nuggets of wisdom for sailors navigating the world’s waters.

In this article I’ll briefly touch on some of the key take-aways.

  • “…some of the old recommendations, including the famous 1-2-3 rule, are no longer endorsed by the National Hurricane Center.” (page 5)
  • Includes definitions of various storm classification terms such as tropical wave, tropical disturbance, tropical cyclone, tropical depression, tropical storm, subtropical cyclone, and so on.
  • How does a tropical cyclone differ from an extratropical cyclone? (page 8)
  • “A lower category storm with a larger wind field can be more hazardous to the mariner by generating a larger area of rough seas and requiring additional evasive action.” (page 10)
  • Formation and life cycle of tropical cyclones (page 12)
  • The seven ingredients for development & intensification (page 12)
  • Size comparison between the largest and smallest tropical cyclones (page 16)
  • The additive effect of rotational and translational wind speed (page 18)
  • Tropical cyclone seasons (page 26)
  • El niño southern oscillation effect on various tropical cyclone basins (page 33)
  • Tropical cyclone motion (page 34)
  • How track forecasting has improved (page 38)
  • “Unfortunately for the mariner, the format varies significantly between centers” (page 39)
  • NWS/NHC products available (pages 41-43)
  • Cone of uncertainty (page 46) – most folks misunderstand this cone!
  • Wind speed probability (page 47)
  • Graphical tropical weather outlook (page 50)
  • Tropical surface analysis (page 52)
  • Tropical cyclone danger graphic (page 54)
  • High wind and associated seas graphic (page 55)
  • “Many mishaps involve mariners making decisions based on old forecasts.” (page 62) – brings to mind the El Faro
  • Receiving tropical cyclone products at sea (pages 62-69)
  • Buys Ballot’s Law (page 70)
  • Six steps for risk analysis (page 72)
  • The outdated 1-2-3 Rule (page 74)
  • “U.S. Navy Ship Routing Officers typically avoid the area with more than a 5% probability of tropical storm force winds, which serves as a reasonable threshold for most large ships.” (page 74)
  • Emergency actions when caught at sea (page 78)
    • See also Weathermuffin’s Small Vessel Weather Compendium (obtainable free by entering your email address at the bottom of this page) for a storm avoidance cheatsheet to maximize CPA

Weathermuffin helps you keep a close watch on tropical cyclones with these features that support NOAA’s recommendations:

  • A single, unified format of cyclone information, so you don’t have to learn and deal with each center’s unique formats.
  • Timely data: cyclone information is generally reflected in the Weathermuffin app within 10 minutes of being published by the authoritative center.
  • Easy-to-interpret graphical depiction of storm track, size, and more, shown on the map in context with your vessel’s position now and in the future.
  • Storm size is depicted graphically using the larger of the 34-knot wind radius and the 12-foot (3.5 m) seas radius.
  • Cyclone information sailors care about:
    • storm track & forecast track
    • storm classification and name
    • speed and direction of travel
    • maximum wind, gusts, and seas
    • 34-knot wind radius and 12-foot (3.5 m) seas radius
    • closest point of approach (CPA) and time to CPA
    • time track and forecast were issued by the authority
    • 48 hour and 7-day development probability
  • Fast download: all cyclone data is quickly downloadable over the Iridium GO!
  • Easy access and visualization of relevant synoptic charts such as tropical surface analysis, tropical cyclone danger graphic, significant wave height analysis, wind and wave forecasts, surface forecasts, wave period and direction, and more.
  • The Ocean Atlas app contains data for historical cyclones from 1980 onwards, as well as other up-to-date climate data useful for passage planning. Ocean Atlas gives you the latest up-to-the-year climate data, which may not be the case for pilot charts or other printed materials.

Learn how sailors can avoid hurricanes.

Leave a Reply

Your email address will not be published. Required fields are marked *