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Old 21-01-2009, 09:26   #1
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How/ where can I learn to read weather files?

We have grib files and downloads and can get all the pretty maps. I understand high and low pressure, fronts etc.
What I cant figure out is how you look at these charts/ files and know where the best direction to go is. For example, if you were crossing the Atlantic, how do you know how to go North, South, straight etc. And how can you spot a good weather window just from these charts? I know you can use a professional weather router, but I'd love to learn how to do it myself.
Anyone know where I can learn this from?
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Old 21-01-2009, 13:35   #2
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Well to really learn the subject in depth I would google the subject or go to amazon.com and look for a good book on the subject.

On this forum you will certainly get some pointers but to develop serious expertise buy a textbook on meteorology.

I am FAR from an expert but can offer a couple of general pointers.

Certain weather maps will show you isobaric lines (a line along which the barometric pressure is equal). High and low pressure centers will have a circular isobaric line around them with of course the highest pressure inside the circle around a high and lowest inside the low circle.

Look at how close together the isobaric lines are between a high and low. The closer together the lines the higher the winds in that area.

Not sure if this is univeral but at least in the areas I know about, bad weather and storms come with lows and good, calmer weather with highs. The lower the pressure in a low the worse the weather.
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Old 21-01-2009, 13:39   #3
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Miss-m,

Here's a link to an article by Michael Carr, a pretty well-respected marine weather guru: Reading Weatherfax Charts . His book, Weather Predicting Simplified: How to Read Weather Charts and Satellite Images, is a very good place to start if you want to get better at understanding marine weather.
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Old 21-01-2009, 15:07   #4
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What I cant figure out is how you look at these charts/ files and know where the best direction to go is.
You probably need to get an advanced degree in meteorology to really get good enough to make a living doing this. But what can help a lot is to review the maps regularly. Do it starting right now! It's amazing how much you learn if you are:

1. Thinking about weather.

2. Studying the map and looking outside several times a day.

3. Studying over time how weather patterns change in your own part of the world. You'll be looking at it so it's not so hard.

4. Also look at what it shows on the map where you really are.

You still want accurate forecasts downloaded or broadcasted but if you have been watching the weather you and really thinking about it everyday you can get better at judging how long you have until something is going to change. Getting a decent barometer and keeping records also helps. if you can being to learn how weather changes it means you'll be better warned when you have to make a change.
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Old 21-01-2009, 15:15   #5
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Starpath School of Navigation Title Page

Here's a company that has a variety of courses that you can take at your leisure.
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Old 22-01-2009, 03:45   #6
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As well as the winds being stronger where the barometric lines are closer together, you can also get a good idea of wind direction from the chart. In the northern hemisphere the winds circle clockwise around a high pressure system and anti-clockwise around a low pressure system. Always.

In the southern hemisphere where I live, the situation is reversed (and helps me remember)... ie cLockwise around a Low etc. Also the entire weather pattern moves slowly east.

That's about it! Sum total of my meteorologicathingamal knowledge. A book sounds like good advice.
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Old 24-01-2009, 05:38   #7
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Does anyone have experience with Starpath? Their website is pretty complete and there is a lot of information there but the courses aren't dirt cheap.
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Old 24-01-2009, 06:09   #8
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The best book, without a doubt, nowadays, is David Burch: "Modern Marine Weather" Amazon.com: Modern Marine Weather: David Burch, Tobias Burch: Books
I am reading it right now, and have read about 40%. It really lives up to it's title. It's the book I wished I had 30 year ago, except for the fact that we had no internet, or access to amazing amount of knowledge now available.
The book Hud mentions is good for further reading and to get to an advanced level try this one: Amazon.com: Heavy Weather Avoidance and Route Design: Ma-Li Chen and Lee S. Chesneau: Books
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Old 24-01-2009, 08:50   #9
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Thanks for those links, cagney. Very good references, indeed!

It really is worth taking the time to learn a bit about how weather systems form and develop. It adds a whole level of understanding to your reading of published forecasts and model output, like GRIB files and sites like PassageWeather.com. It's part of the "self-reliance" ethic so important to cruisers.
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Old 24-01-2009, 09:12   #10
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I forgot to mention that Lee Chesneau ( Lee Chesneau's Marine Weather )
and Joe Sienkiewicz have updated their classical article from 1995
"Mariner’s Guide to the 500 – Millibar Chart" here Mariners Weather Log Vol. 52, No. 3, December 2008
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Old 24-01-2009, 11:55   #11
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I've been scrounging around for other weather books. Does anyone have any comments about Chris Parker's book on Coastal and Offshore weather? And what about David Jones' Caribbean Weather book? Both of these are specialized to the Caribbean and the latter looks like it is a little old but still might be useful.
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Old 24-01-2009, 12:07   #12
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Both of these are specialized to the Caribbean and the latter looks like it is a little old but still might be useful.
Being a little old is not a big deal for you now. They make weather everywhere so the Caribbean is not very special even if it has it's own patterns. Every place has it's own patterns of weather. The bigger picture is what you are attempting to learn. I would be more concerned if it was written so you could understand it. No book is going to get you a job on the Weather Channel. Getting the fundamentals down about how weather works is going to at least get you so you can read weather maps and understand weather forecasts. Making the most of information you can get Cruising is the level of knowledge you are hoping to reach.
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