Having a Feel for the Weather

Having a feel for what the weather may do a few days hence, a day from now, or a few hours from now can mean the difference between a comfortable passage or night at anchor, and a flat-out battle with the forces of nature.

The matter of half a day's time--departing a little sooner or later--can be the difference between life or death.

As little as fifty miles of difference in position can mean a modest gale to be dealt with, or hurricane-force winds.

Unfortunately, we can't totally rely on the forecasters to tell us when to leave on a passage, or whether to stay at anchor. We cannot expect them to advise us to move 50 or 75 miles to the west to avoid the worst of a storm when they may not be sure of a storm track.

Understanding the Basics

Happily, there's an answer for much of this--understanding the basics of what makes weather do what it does, and then having a feel for a set of simple forecasting tools.

Because you are on the spot, the data available to you by looking outside and checking the barometer can be used to make a reasonably accurate forecast most of the time.

With this knowledge in hand, along with a well-found vessel and crew, you are going to have faster, safer, and more comfortable passages.

You will do a better job of avoiding bad weather, and when it cannot be avoided, of mitigating the range of difficulties coming your way.

Towards this goal our Mariner's Weather Handbook takes two tracks. The first is to recite the basics of what makes weather work the way it does.

Then after discussing these basic topics, we will spend quite a lot of time on tactics. You'll learn how to use the passage of fronts and their associated lows to your advantage--whether you're headed up or downwind.

We spend a considerable amount of time on tropical cyclones--the most devastating of all storms. Hopefully, much of the discussion on this topic will remain academic.

Proximity--A Key Ingredient

You may be thinking, "If the professionals have such a hard time, how are we ever going to get it right?".

The answer lies in your proximity to the events as they are unfolding. The professionals are sitting in offices thousands of miles away. They work with images from space, sophisticated computer models, and sometimes real-time data from ships or reporting buoys in your area.

When they have real-time data, if their forecast is broadcast in a timely manner, and if you can receive it clearly, you have all you need.

But often the professionals lack the information you have at your fingertips--wind speed, wind direction, cloud type, barometric pressure, and the trends in all of this data.

With just this locally available information you will be pleasantly surprised at what a good job you can do in foretelling the weather.

Our endeavor in this book is to make you as self-sufficient in weather analysis and tactical decision-making as possible.

You may be interested in knowing that in the last 200,000 miles (plus) of cruising, we have seen less than 48 hours of weather--two blows--that might be considered dangerous. Since most of this sailing was done without benefit of a weather fax or even SSB receiver you can see the odds are very much in your favor.

Today, with a weather fax and the techniques in this book, we would probably have avoided both of those blows.

So, while we dwell throughout the book on the riskier outcomes of various scenarios, we do this to teach evasive action so that you are not caught out.

In this regard there are two areas of the book to which we'd like you to pay particular attention. The first is the use of the 500mb (upper level) fax charts. These are by far the most valuable forecasting tool at our disposal. We cannot emphasize too strongly the importance of understanding these charts, and having a reliable means to receive them.

If you get a handle on the use of 500mb data this will do more to promote your safety, comfort, and mental well-being than anything else you can possibly do in the way of preparation.

The second area of which we'd like you to be mindful deals with tropical storms. There are always warning signals well in advance of these blows, so there is no reason to be caught unawares. We recommend that you study this area carefully even if you are sailing in the tropics in what is normally out of the hurricane season--these storms can occur at almost any time of the year. While out-of-season storms are rare in most parts of the world, it is still worth keeping a weather eye peeled.

Using this Book

Mariner's Weather Handbook is loosely organized into four sections. Initially you will find the basics of what creates the weather, and how low pressure systems and their fronts interact. You will find an emphasis towards onboard forecasting first, based on your current conditions. We then cover what is available in outside weather data, starting with an overview of the forecasting process, as well as a discussion of the various ways of acquiring this data. A major part of this discussion centers around the use of 500mb charts--long the secret weapon of government forecasters and race-winning weather routers.

From here we travel to warmer climates with a discussion of tropical meteorology. The focus is on tropical storms, their forecast, and avoidance.

We then return to discuss tropical storms transitioning to the higher latitudes, and compare extra-tropical and tropical storm structure.

The last section of the book covers a series of topics ranging from land breezes, to fog, to using the Internet for practice and real-world analysis.

You will find extensive discussions of the tactics to be used in both fair and foul weather. And, while heavy weather avoidance is certainly a major part of this book, we hope you will find that by getting up to speed on forecasting, your fair weather passages will be faster and more comfortable than before.

You may want to read some of the sections more than once, as the need arises.

We also suggest you avail yourself of other books (there's a bibliography at the back) and strongly urge you to find a course in weather forecasting. These exist in many junior colleges and universities as well as within the sailing and commercial shipping industry--no book is a substitute for the formal training you can get in the academic environment.

And then practice. Look at the sky, check the barometric pressure, pick up fax charts from the Internet when you're land-bound, and practice making forecasts. Pit your skill against the professionals. You will be pleasantly surprised at how easily you become proficient.

While weather can be serious business, the vast majority of the time conditions will be benign--but forecasting and tactics are still important. Once you get a feel for the weather patterns, and understand tactically how to use these varying patterns, your passages are going to be faster, more comfortable, and a lot more fun.

Our Approach at Sea

A word is probably in order on our own approach to this subject when we are at sea.

First, we make every effort to get as much outside data as possible. We treat this information as suspect until confirmed by firsthand observations. At the same time, we are updating our own analysis of what we think is about to happen, and what's the best way to deal with the unfolding scenario.

There are usually several tactical approaches to every situation. We like to have more than one option, so that if the weather does not go as we or the outside experts project, we have a fallback position.

With weather, as with everything else to do with the sea, there are conservative and there are risky courses of action you can take when dealing with the elements.

We feel it is always better to take the most conservative approach. This may result in a few extra miles sailed, or a delayed departure, but in the end the passages are usually over more quickly and we are a lot more comfortable while we're at sea.

Before you get on with the text, a final word about the risks inherent in weather forecasting is in order.

Weather is the ultimate variable. There are an almost infinite number of possibilities that can happen at any given time. As such, no book can possibly have all the answers within it--not even the most sophisticated computer models can do that.

You always need to be alert to special situations which do not fit the normal rules--or what we say in this text. You may find situations where the weather is unfolding in an entirely unusual manner--or in a way which is totally different from what we've covered herein. When that happens, you need to re-adjust your thinking and look for different possibilities.

We wish you fair winds and smooth seas.