KNOW WHICH WAY the WIND BLOWS
by Dan Lewis, Wavelength Magazine 2007
The big variable in the game of sea kayaking is weather. Not the “Is it going to rain?” kind of weather. Cruise by any kayak shop—they offer slews of paddling jackets and dry-tops that will keep you dry when paddling. And think about it: if you want to have fun outside when it’s raining, where better to go than kayaking? Your legs are in the kayak, so half your body is dry inside!
No, the rain is not a problem. It’s the wind. Wind can really cool you off, especially if you’re wet, which you often are during water sports. Note the selection of insulating under-layers at that shop, from wool to neoprene: all designed to keep you warm when wet. Even on the hottest summer days, a prudent paddler in the Pacific Northwest leaves the cotton in the car.
Wind can cause you to drift and make it difficult to control your boat. In extreme cases, just hanging on to your paddle is a chore. But perhaps the biggest problem posed by wind is that it generates waves – little wind – little waves; big wind – big waves.
This would seem to describe a linear relationship—it is not. Actually, the force on your boat and body increases exponentially as wind speed rises. For example, if the wind speed doubles, the force of the wind will increase by 2 squared, or a factor of 4. Just because you handled 10 knots last time out, don’t think that 15 knots will only be one and a half times as hard—it will be twice as hard.
So how do you minimize exposure to wind? Weather is hard to predict. A few principles will help. Typically, coastal winter weather is dominated by a string of low pressure systems marching across the northern Pacific. A deep low pressure system is called a storm and winds will tend to blow from the southeast, and be accompanied by varying amounts of precipitation, usually in the form of rain.
After a low moves through, the atmosphere will often return to its default setting of high. High pressure systems bring fair weather: winds from the northwest, blue skies and maybe those puffy cumulus clouds.
It is during fair weather events that we get daytime heating of the land by the sun, which usually causes the nor’westerlies to pick up around ten in the morning, peaking out in the afternoon at 20 or 30 knots, typically dying down around sunset.
You don’t need a weatherman to know that your best bet for decent paddling conditions will be in summer, probably early in the morning. It is still necessary to tune in to the marine weather reports for a couple of days prior to your outing, especially the night before and definitely the morning of. Marine weather reports are issued on special VHF radio channels, and are also available on the web and in some locations by phone. Once you have an idea of what kind of winds to expect, you can choose a paddling location.
Another factor that affects the size of waves is fetch. Fetch is the distance of water over which a wind can blow. The open Pacific has a huge amount of fetch; waves there could be coming from Japan. A pond in Iowa has minimal fetch—no matter how hard the wind blows, the waves can’t build up because there’s not enough open water.
Consider whether the wind at your intended destination is blowing onshore or offshore. Offshore winds can be a bit spooky. You go to the beach and it appears to be calm—no fetch, no waves! But let’s say you paddle away from shore. At first you’ll feel a little puff of wind, and as you continue, the wind speed will appear to rise. In a worst case scenario, you could end up in conditions beyond your abilities, unable to turn around or make headway back into the wind; forced to ride it out, paddling downwind to the far side of whatever body of water you’re on.
Of course the scenario above is totally avoidable—strong winds would be forecast on the marine report, and a glance at a map would show you which way you’d drift from your put-in location.
I’d almost rather paddle in an onshore wind for several reasons. First, onshore winds are WYSIWYG (what you see is what you get). If you can’t get off the beach in onshore winds, you may want to consider surfing the net instead! If you do screw up in onshore winds, at least you will blow right back to the shore you came from, and you can walk back to your car. Note that a section of cliffy shoreline can seriously interfere with this contingency plan…
On any large body of water, such as a lake or the ocean, fetch becomes an issue whenever the wind starts blowing. What can you do about it? Try to choose a body of water with minimal fetch—stay in a small, protected bay rather than heading out into a big channel.
It’s best to stay ashore when strong winds are forecast, and remain aware at all times while paddling of your closest and best options for landing (they may not be the same) if the wind comes up suddenly and conditions quickly become unmanageable.
There are many factors involved in kayaking safely. Just picking the right weather conditions and the right location will get you started on the right foot. As your skills and confidence increase, these principles will help you to choose challenges appropriate to your abilities.
For kayakers the most important variable is wind and the resulting sea state. Unfortunately, winds are difficult for meteorologists to forecast, especially in the Pacific Northwest.
The maritime Northwest’s year is almost equally divided into two seasonal weather patterns, each governed by two large atmospheric pressure cells. The Pacific High is always present off the California coast but expands north in the spring to dominate the entire northeast Pacific until early fall. Then the high retreats south and is replaced by the growing Aleutian Low. This low moves south in the fall from the Bering Sea to the Gulf of Alaska to stay through the winter. In spring the low weakens and retreats to the northwest Pacific and the Bering Sea, again replaced with the high.
the summer pattern usually eases during April and gives way in September. Gales (winds stronger than 33 knots) decrease in frequency toward midsummer due to the domination of the stable Pacific High pressure blocking most disturbances from entering the area. Lows and fronts can still bring rain and strong winds, which almost always blow from the south.
Winds can still be an issue in fair weather. As the interior landmass warms, air from high pressure areas in the Pacific Ocean is drawn in producing prevailing winds from the northwest, other than that as influenced by the Strait of Juan de Fuca.
Wind blows down the Strait of Juan de Fuca often at 25 knots in the afternoon. These winds spread north and south at the eastern end of the strait, sending westerlies up into the San Juan Islands and northwesterlies down across Port Townsend and down into northern Puget Sound.
Topography plays an important part in wind direction and force throughout the area. Mountainous seasides channel winds and deflect them as much as 90 degrees. They may also cause intensified winds where forced through a narrow passage or over a saddle between higher hills.
As land heats up on a sunny afternoon, local onshore winds are created. Hence morning is generally the least windy time for paddling. When the sea breeze direction coincides with the prevailing northwesterly, local winds are intensified.