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The morning sky is red, the glass is falling, the GRIBs are downloading

2019 September 1

On any given day in 2019, the average person in a supermarket checkout line knows more about the weather than I did when I set off on my first cruise in my first cruising-racing sailboat.

Americans are saturated with weather. I mean media weather, not atmospheric weather. 

Addicted to the weather forecasts, advice, warnings and breathless reports of meteorological disasters (there is always one going on somewhere some time) available 24/7 on the internet and other media, we are weather junkies. I just counted and found seven weather apps on my iPhone.

And we are all weather experts. Small talk these days can be about the occluded front that messed up plans for a golf outing or the glorious crepuscular rays that were observed radiating above the water. The other day, I heard the arcane meteorological term “derecho” bandied about a coffee shop in discussions about a windstorm that leveled trees in my town.

Weathermen and weatherwomen, once the resident nerds of  TV news programs, are now rock stars. Have you noticed that some of the most glamorous folks on TV are weather presenters (not counting NBC’s Al Roker, who delivers his weather analysis in a suit, tie, fedora and funky, big-rimmed blue glasses)? 

The men are buffed and good at striking heroic poses in front of breaking waves and bending palm trees, all the while employing some mysterious trick to keep perfectly formed baseball hats on their heads in hurricane-force winds. For their part, the weather-star women manage to look fetching standing in knee-deep water in waders while speaking perfect weather lingo. 

That’s just the entertainment side of the weather information phenomenon. There’s another part to it, and it’s the biggest boon to sailors to come along since the invention of GPS. Thanks to the internet, everyone has access to state-of-the-art forecasting models used by meteorologists by downloading the compressed weather data files called GRIBs.

I’m sure most SAILING readers know this, but I’ll throw it in for the record: GRIB stands for Gridded Binary or General Regularly-Distributed Information in Binary Form. Rarely has an acronym been asked to do such heavy lifting.

In short or long form, what this means is that sailors have access to the best weather information available. What’s more, relatively inexpensive onboard software can analyze the data and produce detailed routes for boats to find the fastest or the safest courses through the predicted weather.

This is all wonderful stuff, of course, but frankly I’m a little miffed by it. It’s not fair. Today’s new sailors waltz into our world with instant access to top-shelf weather advice, never having to experience the often unpleasant (albeit character-building) consequences of being utterly clueless about the meteorological traps and ambushes lying in wait for your boat.

Contrast that with sailing in more primitive times. When I entered my first Chicago-Mackinac race, inexperienced and daunted by the looming challenges, I sought out every bit of advice available and found a how-to-win treatise written by a legendary Mac-winning skipper. His weather advice? Watch the TV weather reports every night for the two weeks preceding the race to observe the trends of frontal movements. I’m not making this up.

MAFOR forecasts by radiotelephone were available, but of limited help because their scale was so large they were often irrelevant to an individual boat’s location. Not only that, they were broadcast in code, numbers for everything from the duration of the forecast to the velocity of the wind. The process of translating the forecast into actual language by decoding the numbers was tedious enough to encourage a why-bother attitude.

Traditionalists may have appreciated this, but it seemed odd to me that though we sailed modern plastic vessels we were pretty much in the same boat as the wooden ship sailors of yore when it came to weather. Sometimes we had to rely on the same weather prediction device used by the square-rigger captains who would look at a barometer, rush on deck and bellow, “The glass is falling—take in the topgallants!”

I’ll even confess to occasionally putting my faith in ancient mariners’ weather aphorisms. A red sky in the morning made me uneasy. 

Now I put my faith in the GRIB files generated by GFS, NAM and ECMWF, the American, North American and European weather models. They’ve eliminated excuses for blundering into bad weather (of which, alas, I’ve done plenty), of course, but they’ve also changed the way we go about offshore sailboat racing. Long-distance racing decisions were once influenced by weather, strategy, tactics and performance polars. Now they’re driven by weather, weather, weather and weather.

It was once considered a rookie mistake to sail out of your way to chase predicted weather to find race-winning wind angles and velocity. Now it’s a mistake not to.

Our weather obsession is fed by a GRIB data flow that is both voluminous and so exquisitely detailed it can be micro-focused down to a relatively small area of the water on which you’re sailing. The data can be displayed on maps or in lists that show wind velocity and direction at specific times and locations.

Though the models always differ somewhat, there is no hedging in what each predicts, no suggestion that educated guessing is involved. It is a fact of 21st century life that data is revered and trusted, and the apparent precision of weather data encourages the belief that GRIBs are gospel. If one says that at 0800 the wind will be blowing at 15 knots from 150 degrees at a certain position, you can count it.

Believe that and you’re a candidate to buy the longest suspension bridge in the western hemisphere (hint: it’s a mark of the course of a famous freshwater yacht race). Weather modeling has something in common with every attempt in history to predict the way the atmosphere will behave—it can be wrong.

To wit: On a return cruise from a recent race, we downloaded GRIB files that were so encouraging we started a long passage a day earlier than planned to take advantage of the predicted delightful sailing conditions. Two hours after our pre-dawn departure we were plowing into 20-knot head winds and steep seas. Things went downhill from there, culminating in a cold front arrival that doubled the wind velocity along with the misery factor. 

It was a certified weather ambush. Just like old times.