One thing is certain-it’s going to change (published February 2012)
It’s a common axiom in many parts of the world—if you don’t like the weather, just wait five minutes and it’ll change. For sailors, that can be good or bad news. Sorting the good from the bad before the fact descends upon you requires a little knowledge. The skill is in understanding how the weather will change, how that change will affect you, and what you’d like to do about it—before your choices evaporate like the morning dew and you’re stuck with whatever you get.
I’ve heard the rather trite notions that “the forecasters always get it wrong” or “we’ll just deal with whatever we get.” I’ve certainly witnessed the occasional incorrect forecast and, like it or not, I’ve always dealt with whatever I’ve gotten. But those glib statements, usually meant to exude a sense of bravado, generally represent a cop out and a reluctance to learn new ways. As sailors playing the game, we can learn to be chess masters rather than pawns, and while sailing, you will be playing against the weather. There will be the occasional unforeseen development, and you’ll have to deal with it, but your odds of getting what you want will be greatly improved by learning how to read the weather, regardless of whether you’re working your way down the coast, across an ocean or toward the Caribbean. Your safety as well as your comfort and efficiency will be improved, and there are some extremely helpful and convenient resources available to get you to that level of understanding.
There are a variety of places to start. Pick your poison. Whether you grab a book about weather, attend a live seminar or sit in front of your computer for a webinar—live or recorded—you will gain from the information that others are putting in front of you. Learn from their experiences (and mistakes). The tools you’ll learn to read and use include maps, satellite images, barometers and wind instruments. Together, they form a wealth of information and lead to informed action on your part. It’s not rocket science. Well, in truth some of it is, but those parts aren’t your concern. Thanks to the efforts of NOAA, the Ocean Prediction Center, the NWS and countless other organizations and your own tax dollars, the information is close at hand.
Of course, reality is what you see and feel. The forecast may not call for rain or a wind shift, but understanding it will help you realize the larger implications of the synoptic scale weather pattern. When that lone cloud passes, the larger scale reality is likely to be revealed. Understanding the greater perspective helps you put the weather around you in context. You will begin to notice how the things you see fit together with the maps and satellite images that you access online, through your weather fax or over weather broadcasts. The squall line that is approaching could very well be the physical precursor to the cold front to follow. And the lower the cloud cover in that squall line, the greater the short-term gusts may be. When the squall line passes and the cold front actually comes through, perhaps 100 miles behind the initial squalls, the passing of the cold front will be announced by the clearing in the skies above. The cold, dry air in the cold air mass behind the front will be signaled by clearing skies overhead. It all becomes logical and readily understandable. What you see will become correlated with your larger understanding of weather and how it works—if you take the time to understand the building blocks that make weather work.
Weather, of course, works in conjunction with the elements around us. Land heats up faster than water. Warm currents, such as the Gulf Stream, add heat energy to the atmosphere. Those things influence the weather on a local scale. Clouds are more readily created, and the clouds imply rising air. The rising air implies circulation, both vertical and horizontal. There are often wind shifts under clouds. It only stands to reason, when you start to understand the pieces of the puzzle and learn how to put them together.
Less commonly understood, strong currents such as the Gulf Stream raise or lower the sea level in places. Satellite altimetry data can also be accessed, which shows how the water height is distorted and how the water flows in a particular large scale area. But again, our eyes and other senses can also serve as guides to the location of the Stream.
Miles-long streams of Sargasso weed often foretell of an approach to the Gulf Stream. Like flotsam along a tide line, the Sargasso weed lines up near the edges of the Stream, sometimes less than five miles from the actual current. The sea temperature rises in the Gulf Stream, and as you approach the Stream, you will often see flying fish or little Portuguese Men-o-war, usually associated with tropical or warm waters. Maybe it’s time to get your fishing lines deployed as the tuna will also be congregated around the edges of the warm water, looking for something to feed on.
Waves and their shapes add to the story around us. Wave shapes change as the current changes. Wind blowing against current will create a steeper wave for a given wind speed. Wind with the current will create a flatter wave or a wider distance between lower crests. Small breaking waves may indicate relatively shallow water, such as the presence of a reef.
The knowledge base for all of the things to do with weather and oceanography is far too large for one magazine article. How we apply that information is another thread of thought. I’ve tried to convey the thought process I use to determine how best to route myself to take advantage of the weather and avoid offshore pitfalls. You can find further information by using the Weather Routing Wizard that Lou Roberts and I provide for free at www.weather4sailors.com. I have also provided a list of suggested resources with this article (see sidebar). The efforts you put into exploring these topics will come back to reward you with safer, more enjoyable sailing. I’m sure.
Much of the information out there is free. Whether or not you choose to avail yourself of it is up to you. But if you surround yourself with knowledgeable people, learn their tricks and pick their brains, it will serve you well as you sail wherever the winds will take you. Enjoy it all.