Living Aboard a Boat Marine Weather

U is for Under the Weather

Monday, April 25, 2016S.V. CAMBRIA


During the month of April, we're participating in the Blogging From A to Z Challenge where every day (excluding Sundays) we'll be posting to the blog . . . alphabetically. The overall theme we've chosen to tie all the entries together is living aboard a boat and cruising – things we've learned along the way: our thoughts, reflections, and tips for those just starting out or who are interested in this lifestyle.



Note: I really want to thank David for writing this blog post, his first. While we consult and confer over the weather on a daily basis during the cruising season, forming our own forecasts upon which we make decisions, he’s the one who accesses and puts together all of the information that helps keep us safe.

The weather . . .  and weather forecasts! Probably one of the most frequently discussed and debated topics among sailors of all kinds; whether in the bar, the clubhouse, or on the VHF or SSB. In fact wherever two sailors meet in conversation the subject is more than likely to arise. And for very good reason. No matter if passage-making offshore for several weeks, sailing  near-coastal, or sailing in protected waters, having a good, accurate (not to mention favourable) weather forecast for the duration of your time on the water is or should be a significant factor in a captain’s decision-making process. The unexpected arrival of bad weather while on the water can not only spoil your day but can also create conditions ranging anywhere from uncomfortable to actually challenging your survival.

We have available a variety of good, up-to-date weather information, both from governmental agencies, public entities such as universities, and private sources of all kinds, whether by internet or e-mail, VHF radio or suitably capable SSB (or HAM) radio.

While we’re on the subject, most people don’t realize that there are less than a handful of principal weather forecasting “models/programmes” in use worldwide – GFS produced by the U.S., ECMWF produced by a private organization funded by E.U. member nations, and UKMET produced by the U.K. All legitimate forecasts are based on one, or more typically, a blended combination of the products of these models. Complex algorithm-based, and requiring super-computers for processing, the models are, disappointingly, not quite as accurate or consistent as you would imagine (or perhaps expect) and still often disagree quite fundamentally between themselves in respect of the predicted movement, track, speed or strength of any particular weather pattern, although performance of each of the respective programmes is being constantly monitored and improved. To read more about inaccuracies in and between the models go to AccuWeather.com.

If this really is the case then we’re already at a fair disadvantage at the outset in trying to develop any forecast. I know it’s the easiest thing in the world to “start throwing rocks” over an inaccurate forecast but, being realistic, we should understand that, even for the professionals, weather forecasting is as much the art of balancing between probabilities and probable outcomes as it is a precise science. And if this is the case, from my perspective it makes sense for the purposes of sailors such as ourselves to gather and compare forecast information from as many independent sources and in as many forms as possible. And there’s yet one more option: learning how to read and interpret synoptic charts and produce your own forecasts. In case it’s an unfamiliar term, a synoptic chart is a visual representation of the weather conditions being experienced across any given area. Once you can interpret the information contained in these charts you can develop a reasonable prediction of the weather conditions that are likely to develop in the near future. Learning to do so is not a hard skill to develop and one which can be extremely rewarding, let alone very useful. Some may even say essential.

So here we go . . . the following are a number of the sources we have consistently used and relied upon over the years*: 



Providing forecast synoptic charts, which show surface barometric pressure, isobars plotted at 2 millibar (hectopascal) intervals, forecast wind speed and direction, and anticipated 6-hour rainfall, at 6 hour intervals for 3, 7 and 10 days for most areas of the world, MetVUW remains one of our favourite weather sources. We’ve consistently consulted this site in developing/comparing forecasts in connection with the thousands of miles in offshore, near-shore, and coastal passages we’ve covered since 2002, when we first became aware of its existence in New Zealand, and absolutely swear by its content reliability. Managed by Jim McGregor at the Victoria University in Wellington, New Zealand (and presumably undergraduate and graduate students from its School of Meteorology) we’ve found the published forecast product to be consistently good. If I was asked to place a performance percentage on it I would have to say better than 95 - 98% in forecast accuracy, certainly for the areas of interest to us. Simply stated, thus far in nearly fifteen years of cruising, I’ve never been disappointed by its’ forecast data. I’m a fan. ‘Nuff said.

Providing current weather forecasts for marine and coastal areas of the US through regularly updated text and graphic files.

Providing near real-time imagery from NOAA geostationary satellite network. Among a variety of other images available, the most commonly used include area imaging showing visual spectrum, infra-red spectrum, and water vapour scan.

Providing current weather forecasts and information for Canada in text form.

Insight into local weather conditions and patterns with updated forecasts written by the Pacific Northwest’s weather guru, Cliff Mass. 

Bob provides a weekly evaluation of current weather patterns in and around the South Pacific and is the cruising sailor’s go-to-guy when it comes to the weather. 

If you’d like to learn how to have NOAA forecasts sent directly to your email account, this article we wrote for Three Sheets Northwest gives you step-by-step instructions.

* We do consult other sources through apps (NOAA Hi-Def Radar, Pocket Grib, Sail Flow) but the list represents our primary weather resources.

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12 comments

  1. We'd both like to take a class in weather 'forecasting'. There is a lot to look at on a chart like that and I am easily visually over stimulated so learning to focus on the important stuff and screen out whatever I don't need in the moment will be critical. Thanks for putting the weather stuff all in one place. When we are at home, not out on the boat, we read The Weather Cafe, by Rufus. http://ovs.com/wx-cafe

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    1. Thanks for the link. The Wx Cafe looks like a good source of information for overall weather patterns. Unfortunately, he agrees with everything we've been seeing -- a likely return to cooler temperatures when we drop our lines on the first of May.

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  2. It is so funny when I think about it... People in Belgium have the tendency to always talk about the weather as small talk (because they have nothing else to talk about?). So much so, that it is becoming a joke. Yet, the outcome of the weather never really mattered that much. As sailors, who also always talk about the weather, I can see more merit to discussing this subject. So now, when I talk about the weather in Belgium, I say "At least we don't have to leave port!" :-) The weather has defined our life for eight years and I am happy to report that it is an incredibly nice side-effect of living on land now that we don't have to follow the daily reports! Or, have to get up early for it!

    Liesbet @ Roaming About – A Life Less Ordinary

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    1. I know exactly what you're saying. Those months that we spend visiting family over the holidays is such a nice break from weather gathering and organizing our lives based on the forecast.

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  3. Reminds of the schoolchild tongue twister: Whether the weather be fine, or whether the weather be not; we'll weather the weather, whatever the weather, whether we like it or not!
    All the internet resources we have currently are amazing; we used to have to call the FAA's Flight Service line for aviation weather; now there's an app for that! -Lucy

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    1. In the 70s, my dad worked with Doppler radar in Norman, OK. I went down to visit him one summer and he took me to work. The computers took up a couple of large trailers and were reel to reel. Today, all we have to do is open an app. It's great!

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  4. Although I'm not a sailor, I found this fascinating! My son, now 14, was spellbound during weather forecasts when he was a toddler. Whatever he was doing at the time those weather maps came up, he would drop and just stand there and stare.

    Boldly Going Through the Alphabet!
    @shanjeniah
    Part-Time Minion for Holton's Heroes
    shanjeniah's Lovely Chaos

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    1. "Bodly Going Through the Alphabet!" -- I love it! That's so interesting about you son . . . I wonder what it was that caught his attention (the colours on radar?). Thanks for stopping by the blog and commenting. We really appreciate it!

      Cheers.

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  5. I am always surprised to meet other sailors or liveaboards who *can't* quote you the forecast for at least the next 24 hours off the top of their heads, or read it from the pattern of the clouds. It's become so utterly second nature for me.

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    1. I know. There's a family that's cruising down in the Caribbean for the first time and they were complaining on Facebook about NOAA's forecast being way off because they had no idea that you need to allow for a 50% differential either way in forecasted wind speeds. It was really disappointing.

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  6. Well done David! We'll expect to see you posting around here more often :-) Great info and advice. I hadn't known that there were only a few weather forecasting models/programs until I spend last hurricane season in Florida and started paying a lot more attention to the weather forecasts and their sources, especially when they differed so much.

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    1. Lol. He said not to hold your breath (which is a real shame because the guy's a walking encyclopedia).

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