The Weather Notebook

Watching the weather is among the most important things we did during our cruising years. In the beginning we muddled our way through trying to learn about weather by reading books, and making notes from information we got over the radio or the Internet. Sometimes Pat spent 4-5 hours a day on weather issues. As it came time to create this part of the website, however, she was forced to sit back and think about how she did this which was a helpful exercise. Access to sources for weather information is found on the Weather page of our website.



Table of Contents for this Article
1. Weather Nets 2. Identifying Weather Windows 3. Daily Observations

         Note that important non-weather items that come up on various radio nets were recorded, for convenience, in the Weather Notebook. And, weather observations while underway were recorded in the Deck Log rather than the Weather Notebook.

         Our Weather Notebook was a spiral notebook. A 100-sheet notebook lasted us about 6 months. On the outside front cover of the notebook we pasted the schedule of weather transmissions, including weather fax schedules, and Nets, noting the times (UCT and local), SSB channels, and transmission frequencies. Inside the front cover we kept a list of shorthand used in transcribing the NWS forecasts heard over the radio (following the method recommended by Bruce Van Sant in his book A Gentleman's Guide to Passages South.

         The front pages of the notebook were used for daily notes, and the back pages were formatted as tables for identifying weather windows and making weather observations. Below is a description of how we recorded and tracked weather data in our Weather Notebook.

 

1. Weather Nets

         Notes from listening to daily weather radio broadcasts and nets were made in the front pages of the notebook. The margins were used for flagging the date, and reference topics so that they stood out easily, and quickly yielded sought-after information when we looked for it later. The day and date were put in a rectangular box in the margin. Other items that we flagged in the margins were capital letters in a circle: "I" for safety and security incidents that were reported; "N" for navigation hints; "R" for radio frequency information; and "P" for emergency and priority items from the various nets (usually the boat names for which there was a watch underway).

         The notes in the body of the pages were formatted as follows: next to the day and date, we listed the weather source (Net name or broadcaster) which was underlined so it was easy to see. Following the name, on the same line, was the SSB channel and frequency, and the quality of the transmission (Readability on a scale of 1-5, with 5 being excellent, and Strength on the same scale.) Underneath this heading the notes were made. If listening to a NWS voice report, shorthand was used as described above. If a weather fax was received, a note of the time and title of the weatherfax chart(s) was recorded. If a text or Navtext forecast was received and stored on the computer, that was also noted. At the end of the last set of notes for the day, a line was drawn across the page.

 

2. Identifying Weather Windows

         A "weather window" for a coastal or offshore passage is an acceptable range of wind and sea conditions lasting for a long enough period to complete a passage (or remain safely in an anchorage) and which can reasonably be expected to occur with some regularity in the area to be transited, taking into account the modifying effects of nearby land masses.

Acceptable conditions depend on the course to be taken relative to the wind and swell directions. Bruce Van Sant in his book The Gentleman's Guide to Passages South offers a useful rule of thumb for comfortable passage-making in a small boat in the Caribbean. "For progressing directly into the wind, look for Beaufort Force 1. Add one Beaufort Force for each compass point working aft from the bow until reaching Force 6 when the wind is astern." In other words, if wind and course direction are similar, stronger winds are acceptable--in fact desirable, for a faster passage. Conversely, if wind and course direction are opposing, then lighter winds are necessary to make way in reasonable comfort. As an example, we defined a weather window for travel against the trade winds from Luperon in the Dominican Republic to Boqueron in Puerto Rico as "a 4-day forecast of winds east to southeast less than 15 knots, seas 3-5 feet, no northerly swells." We thought it was a good idea to put in writing a description of the required weather window, because then it became internalized and it became more obvious when one was coming as we tracked the weather forecasts.

         Tracking forecasts requires the use of some kind of form. The one we used is made up according to the sample given by Bruce Van Sant in the above-referenced book. While this form was formatted for Caribbean weather tracking, it should fit most other situations. The form was made by dividing a page of the weather notebook into 3 sections of columns as follows:

         The first (left hand) section had 5 columns for:

         The second and third sections were identical, and both were divided vertically into 4 columns for:

         The second and third sections allowed the tracking of forecasts as we moved from one forecast area to another. In the second section of the form we initially tracked an 80-20 mix of the NWS Offshore Forecast for the Southwest North Atlantic (SWNA) and the Eastern Caribbean. In the third section we tracked the forecast for a 20-80 mix of the two forecasts. As we moved south through the Caribbean instead of the SWNA we tracked the Tropical North Atlantic and the Eastern Caribbean forecasts.

         We used one line of the form for each day's forecast. For the current day, we filled out the forecast line in ink. For the subsequent days of the forecast we wrote the lines out in pencil, so they could be erased and changed as/if subsequent forecasts change. In the first section we wrote data for the first forecast area in the upper part of the line, and for the second forecast area in the lower part of the line.

         When we saw a weather window coming up, we highlighted the date it began in yellow and began departure preparations. If the window held up, we kept on highlighting the next date of the window as the days unfolded, and made decisions as to the timing of departure.

         While underway, weather forecasts continued to be collected to see if the length of the window was shortening or lengthening.

         Recording the forecast information in this way made it easy to see a weather window approaching. If departure is delayed until a window is forecast, even if the forecast is wrong conditions are extremely unlikely to deteriorate so badly that the passage is truly miserable. Of course, if a passage takes longer than the weather forecasts reach out, then other considerations must be taken into account. Wuch as is the case for ocean crossings.

 

3. Daily Weather Observations.

         When at anchor or docked, we made daily weather observations in another table at the back of the Weather Notebook. This table ran across a single page, which we divided into vertical columns for recording each of the following elements:

         A line of this table was filled out at the same time each day. If we were closely tracking a weather system, as in anticipation of the arrival of a storm, then a line was filled out more frequently, such as every 4-8 hours.

         Even when we were in harbor for an extended period, we kept track of the daily weather observations, and the NWS Offshore Report (which we get every morning along with our e-mail from Winlink) and filled out both tables at the back of the notebook. We also usually listened to at least one Net each day so we could hear about unusual happenings and see what was heading our way. [We got caught off guard one night in the Bahamas when a storm came up in the night - we nearly lost our dinghy and some others in Marsh Harbour lost their boat.]

         Recording the weather each day does take some discipline, but there is no better way to begin to understand weather patterns in your area, and weather systems in general, than to really observe weather changes before your eyes over an extended period. When these observations are considered in light of the current forecast, even more insight is gained.

 

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Bill Dillon (KG4QFM)
and
Pat Watt (KG4QFQ)
This page was last modified on August 9, 2009

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