Weather routing for passages

Jamie will be the first to tell you he’s not a weather router. But weather advice has crept into the work we do with coaching clients, as we seek to help them cruise happily. Getting caught in bad weather due to misjudging a forecast or failing to read conditions – common errors for new cruisers – can kill the dream. Here, he writes about what it’s like offering weather guidance, and offers a hint at the visceral experience of fending off dragons.

Totem hopping anchorages off the coast of Baja California Sur

Unicorns and Dragons: confessions of an amateur weather router

On this June day, I have two boats galloping north at 10 knots. The sailing is nice, boosted by 3 knots of Gulf Stream current along Florida’s east coast. This has elements of a unicorn passage. After dark, it’ll be all dragons. I’m anxious for both families. I didn’t exactly send them out into this night. But I didn’t stop them either. Realtime weather radar shows heavier rain approaching. Florida now has tornado and flood warnings. Damn. Lightning hotspots continue to increase along the coastline. The dragons are coming. 1,700 miles west, Totem bobs in softening afternoon wind waves in the Sea of Cortez. We haven’t had a drop of rain in 6 months. No dragons either. We’ll have a gorgeous full moon rising over Isla Carmen in a few hours. Nothing like my Gulf Stream boats speeding through darkness and dragon fire. I am the chess master, sliding pieces past danger. I am the fool, thinking I control the board.

I’ve only recently come to accept that through extended support to our coaching clients, I provide a weather routing service. I’m not a meteorologist, not even a pretend one. I’m never the assertive voice when a group of sailors debate a weather window for the next passage. Information sharing is helpful. Selling an interpretation only masks a hidden agenda. I thought I understood weather forecasting pretty well when I was a racing sailor. Weather had tactical value and I was competitive. Then came the first big and very unexpected squall while delivering a J/35 to Newport, RI. Didn’t see that coming, but could have if I’d known where to look.

Family cruising in Puget Sound and beyond shifted desired weather traits from tactical to comfortable. The unicorn passage: fully at ease with surroundings in the magic and enchantment of glorious sailing. Unicorns are rare, elusive. Waiting is tedious; not getting you to that next beautiful anchorage you’ve dreamt of, frustrating. Instead, interpret the forecast and go. Rarely expecting unicorns, always hoping not to see dragons. Sometimes getting it right. Sometimes not, always comparing and contrasting forecast and reality after the anchor dropped. After hundreds of passages and assessments, my technical weather knowledge is hopelessly mediocre. My particular weather superpower is translating meteorological data into “this is what it’s going to be like.”

My Gulf Stream boats aren’t off to the next dreamy anchorage. They’re retreating to neutral territory. Like many, they’d been COVID-19 restricted in the Caribbean. Uncertainty of a global pandemic and hurricane season looming like a nightmare monster set them on a path to Maine. It’s a return to home for one family. A gorgeous new cruising region for the other. A big step closer to predictability for both. The path is about 2,500 NM long. Beginning in turquoise water of the US Virgin Islands, where warming temperatures bring increasingly volatile weather. Going north in May and June quickly bumps into colder weather and frequent gales springing from the east coast out into the cold Atlantic.

Sailbot underway, headsail up, as the sun rises from the ocean horizon into cottony clouds
Serendipity, northbound. Photo: Stephanie Ferrie

A few weeks before picking a good enough window to depart paradise, we began the conversation of which route home. We sailed Totem from the Caribbean to New England in 2016, on a direct route via Bermuda. This shaved 1,000 NM from a path along the US coast. Bermuda was closed and the likelihood of gales was high, so, no go. A less offshore route meant skirting the Bahamas, but they were also closed – even for vessels in transit. This longer path without bailout options suddenly got riskier. Fortunately, Salty Dawg Rally organizers stepped in to help. They worked with Bahamian officials to create an innocent passage status list of boats for cruisers repatriating the US and Canada. Once on this list, crews could stop in Bahamas to wait out weather, or procure food and fuel.

With a bailout in Bahamas possible, most of the dozen boats that sought out professional weather guidance from this amateur router preferred to skirt east of Bahamas and make landfall in Chesapeake Bay. This unlikely outcome wasn’t realized by any of them. Through the weather window, I could point out dragons lurking. Boats began peeling off to take innocent passage through the Bahamas. Better to make some progress than wait and wait for the unicorn passage. These boats leap frogged through the Bahamas, unable to step ashore but grateful for the respite. Each made landfall in Florida.

My last two boats, patient or stubborn I won’t say. As their weather router, it’s not my role to tell them when or where to go. It has to be their choice. It can be frustrating, when they don’t follow what I think they should do. Then I remember the times I choose poorly. This includes last night on Totem. I thought the afternoon swell would fade for a flat night and easy sleeping. Instead it was a restless, rolly night at anchor. There is no crystal ball. I don’t push my interpretation, only describe what I see.

A huge low off of New England, with trough extending to the Bahamas, blah, blah, blah. I picture myself with the young families. One with some offshore experience; the other, relatively minimal. Both boats added experienced crew to ease their burden. With a gift of better weather, they managed nicely. Weather got more complicated as they went, but a Florida landfall was made without drama.

Tryptych image shows GRIB rain forecast, compared with real-time weather radar, compared with real-time lightning...differences to observe.

On this night, northbound along the Florida coast, finesse is the key. I described volatile conditions before they set off. No bad wind or waves, but potential squalls to 40 knots, and lightning. Those dragons are real and can be terrifying. A quick start guide to successful family cruising would do well starting with Rule #1: Avoid Terrifying.

My guidance was for a slow start to let the band of unsettled weather pass ahead. I watched the satisfying progress on their satellite tracker positions. They were only 50 miles offshore, within real-time weather radar range. With Blitzortung, an online resource, I could track real-time lightning strikes. On another browser tab I rechecked the GRIB Rain forecast for the 20th time. Lifeless grey blobs, with smaller pink ones denoting rain intensity. Lifeless, almost meaningless until you see the dull blobs as the smoke and flames from dragon fire. That gets the heart rate up. As does this time lapse video Kevin took of the lighting, which I think might violate Rule #1 above.

The tools I used aren’t all meant for piloting, but that’s how I used them: to navigate around hazards. Crudely plotting the lightning’s advance (radar and lightning screens didn’t show lat/long lines) I went against my own rule not to tell them what to do. “Speed now please, all you can make. And change course ten degrees to starboard,” I typed into the InReach message box. The screen confirmed the message sent. Several minutes passed before the reply arrived, “Headsail out, sails trimmed, and course changed. Making out lightning in the distance.”

From Serendipity‘s PredictWind tracking page: the route from Florida to Virginia

Virtual chess and mythical creatures. I could feel their tension as lightning approached. Almost hear the voice crack, if there was a voice in the next message, “lighting is getting intense, will we miss it?” With a few more course adjustments, volatile weather passed just south of the two boats. Actual conditions reflected forecast conditions pretty well, except for being 40 miles closer to my boats then the lifeless grey blobs showed. I learned along time ago that the weather isn’t supposed to do what the forecast says. The dragons that were supposed to strike fear deeper into the night, was now gorgeous lightning safely astern. Another experience. Another assessment. Another way to express lifeless grey blobs.

Epilogue: after these safe arrivals, the crew perspectives were a relief to hear. It might have been tense at times, but the takeaway from Abeona‘s ever-positive first mate was how startlingly beautiful the skies were as the line of lightning passed behind them. Serendipity’s crew probably only missed having to prioritize routing for weather instead of fish! These vessels continued north and treated us to a stream of photos from Chesapeake up through Maine on their summer adventures. Abeona crew’s family sabbatical adventures are drawing to a close; their Catana 42 is for sale. Regular readers will remember Serendipity’s Kevin is FearKnot Fishing; he shared his tips/tricks on a recent TOTEM TALKS, after which we finally caught a dorado again.

Abeona at ease in Maine. Photo: Jeff / Jen Milum

10 Responses

  1. Although you attest to not being experts on weather, you knowledge and experience are invaluable to those if us who lack both. Kristi and I have made a number of passage, and with your help, we’ve had an understanding and a good idea what to expect each time. We can’t thank you both enough for sharing your extensive knowledge and providing guidance with us novices!

  2. We echo Kevin’s remark and are grateful. As I’ve repeatedly stated, “we don’t know what we don’t know” but want to learn. We’ve definitely learned that most of the time “misery is optional”.

  3. Hey, I’m sure I’m not saying anything new here, but have a look at QtVLM for weather routing, in particular with the advanced options for avoiding winds above X, waves above X, etc…

    1. Hey Brian -Thanks – I do know of qtVlm and plenty of others. But… there’s a lot more to weather routing than apps. These are tools like hammer and chisel, but they don’t build the boat. For example. Apps that offer a route to avoid waves above X height are completely misleading.
      1. Waves forecasts are the least accurate of all GRIB elements. Models don’t account for features that affect waves height, such as bottom contour, coastal shapes, contrary currents, etc. A broader area may have X wave height, but add an apposing current or cape and waves can grow to Y and Z heights.
      2. Waves forecasts are often interpreted incorrectly as the max wave height, but in fact are the average of significant wave height. By definition, if you set X as max height that’s what the app is routing you around, but waves up to that average height will be bigger part of the time. And X height limiter doesn’t combine different waves height – as in a swell (dying wave) coming from one direction and wind wave.

      I encourage all sailors to learn their preferred tools well. They all have pros/cons, so collect many and use them for what they do well.

      1. Hi Jamie, thanks for the response. As you say, we’re far from having a “TomTom for the seas” whose directions we can just follow blindly. I did find it interesting to play around with this and see what can be taken into consideration straight off the bat in these routing programs.

        In the end, they provide a recommendation based on the provided data to which reality should be applied liberally :). But as you say, it’s all dependent on the quality of the input data combined with the local land and seabed effects that are much harder to take into account from a software perspective, so we need to rely on this being taken into account in high-res GRIB simulations, and by applying a sailor’s experience to the predicted weather.

        We already have a lot of different sources for GRIBs here in Europe, so the trick is to find the most reliable combination, and find out how much additional sailor’s experience to apply for these to match with reality..

  4. Spot on Jamie. I’ve yet to see a GRIB (we use PW) accurately predict waves in the area of bottom contour changes (sea mounts, continental shelf etc), around islands with tall mountains or passages with changes in current direction and velocities whilst traveling between islands. They’re just not at that level of resolution yet. The eastern Caribbean is a great example. Our least favorite sea state is a swell from one direction and wind waves from another and not in “sync”. It can last for days and be miserable. That condition won’t appear on standard GRIBS unless you know how and where to look. Additionally, it’s important to know WHY the GRIB is forecasting what it is. I always try and have a surface and 500mb chart available when viewing GRIBS for routing. Trends are also critically important. When a forecast is not what is predicted, it’s time to figure out WHY to avoid any ugly surprise. There will be reason. As you noted, Apps are a great tool, but you need the whole tool box to sail safely with some degree of comfort. I cringe a bit when I hear someone preparing a route and stating they get their forecast from “X” only.

Comments are closed.