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Monday, September 6, 2010

Weather, or not.



Another important factor when paddling is weather. Understanding what is happening now, and what may happen in the near future. Being in small craft, sitting on the water line, it is very important that we think about weather a great deal. Weather, tides, and currents are a big part of the decision making process. We need to be thinking about all three. Should we be on the water or off? Can we reach a planned destination or should we plan an alternate?

Weather, like tides, can be very complicated. But for the most part we can simplify to get the information we need to help us make the important decisions.

Whenever I paddle I wear a watch with a barometer. I helps me keep track of the changes in Barometric pressure in my immediate vicinity. It is the changes over time that are important. I also carry a VHF radio, with a weather band. This way I can listen to the weather report for the surrounding weather stations to know what is happening in all directions.

I use the information from the barometer, and the vhf and my senses, to form a picture if what is happening, and what may happen in the immediate future. While weather forecasts online, and on television may go seven to ten days into the future, I really don't believe a weather forecast more than three days out. There are too many variables that can effect what has been forecasted.

Here are some factors to keep in mind:

In general terms West to East, because of the jet stream. If you want to know what tomorrows weather is going to be, look a couple of hundred miles to the west.

In the northern hemisphere HIGH pressure systems bring cool, dry air. They flow in a clockwise direction. Air flows away from the high pressure center, and the coriolis effect makes it turn in a clockwise direction.

Also in the northern hemisphere LOW pressure systems bring warm, moist air. They flow in a counter clockwise direction. The best example of an extreme low pressure system is a hurricane. Where winds fight to get to the center of an extreme low pressure center, and for a circle, or eyewall.

Air, and the associated 'weather' flows from areas of high pressure to low pressure.

High pressure is 'good' weather.

Low pressure is 'bad' weather.

With this little bit of knowledge we can do basic weather prediction. Clear skies are the work of high pressure systems. I know if my barometer is falling rapidly, then bad weather will follow, as the falling pressure means any moist air will 'fall' into the center of the low. This moving air, is going to make wind, and then potentially rain.

High pressure is going to push the 'lows' away, and with them take all the moist air. But that high is going to flow east - due to the jet stream - and will slowly move away.

When bad weather gets pushed away by a high, there is usually high winds, as the high gets pushed away, air has to fill the void.

So I am watching my barometer for an overview of what is happening to the air pressure around me. At night, and in the morning I am listening to the weather report to get an idea what is happening to the west. I am also listening for the wind report. What kinds of wind will I be facing tomorrow when I try to paddle to my next destination.

It is wind, not rain, that is our limiting factor. With wind comes waves, and those two things are going to keep us from making good progress, as well as making it harder to get off the water should we have a problem. I will paddle all day long in the rain, but wind, wind worries me.

Wind will slow our progress, or make our forward progress when it comes from behind at least tricky - I think the best test for a kayak is how it paddles in a following sea. That is when kayaks get squirrely - if not down right dangerous. I don't mind waves on their own, but where waves interact with land is where things get dangerous, made more so by wind pushing you into land. Wind makes a good situation bad, and a bad situation worse. pay close attention to the wind.

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