Hurricane season and the Mariners 1-2-3 rule

From Paul Squire a Marine Surveyor

Today is the first official day of the Atlantic Basin Hurricane Season and we have already experienced 2 named tropical storms. Any marine surveyor in Florida is getting pretty busy as people are preparing their boats for what could possibly be an intense hurricane season. This may be a good time to review the Mariners 1-2-3 Rule. There some that are saying that we should even revise this rule to reflect the improvements in storm tracking predictions. This rule was established in in the 1970′s and uses weather prediction models from the 1990′s.

1-2-3 rule

The 1-2-3 rule (mariners’ 1-2-3 rule or danger area) is a guideline commonly taught to mariners for severe storm (specifically hurricane and tropical storm) tracking and prediction. It refers to the rounded long-term NHC/TPC forecast errors of 100-200-300 nautical miles at 24-48-72 hours, respectively. However, these errors have decreased to near 50-100-150 as NHC forecasters become more accurate. The “danger area” to be avoided is constructed by expanding the forecast path by a radius equal to the respective hundreds of miles plus the forecast wind radii (size of the storm at those hours).

Courtesy of Wikipedia.

Lee Chesneau, a former Ocean Prediction Center meteorologist, suggest that we revise this rule to reflect these advances:

“The overall skills scores of the NHC for track location which the wind radii extends from, has vastly improved. The 1-2-3 Rule today should include the more accurate skill score data that adds up to about 1 degree of latitude (60nm) at 24 hours, 2 degrees (120nm) at 48 hours, and 3 degrees (180NM) at 72 hours.“

This is something that will be up for discussion and debate as the Hurricane Season continues and. Any marine surveyor should be aware of any changes to this rule to be able to adequately inform their clients during this season.

You can read more about this at the Ocean Weather Services Blog.

We will be publishing an article on what to look for when you survey your boat in preparation for any trips during the season. Captain Paul Squire is a marine surveyor in Fort Lauderdale that offers tips and information.