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Reading the Weather
By Tom WatsonI headed out on a long, twelve-mile paddle to the outer islands that protect the island of Kodiak from a 3,000-mile fetch across the Pacific Ocean. The sky was a cloudless blue; the water (yup, you guessed it) smooth as glass! Confident of the stability of those conditions, I could circumnavigate along the outer ring of rocks and reefs so I set out without even consulting marine weather. My eyes were my weather station; too bad my brain wasn't also.As a fish o'er whose head surge the waves of the sea,
In our great sea of air, the fish becomes me.
And high o'er my head waves of air churn and roll;
Deep currents, deep tides move the air, move my soul.- Don Haggerty "Rhymes to Predict the Weather"
Rounding the last rock I felt a subtle hint of things to come. A very subdued but cold breeze pecked me on the cheek. A faint ripple sidewinded its way across the water in front of my boat. Within five minutes the sky began filling with sinister looking gray clouds. Within ten minutes, calm seas and gentle breezes had evolved into two foot waves and blowing 12 to 15 knots. I set my sights on a channel buoy about half way across and hunkered down for the straight-line paddle. Within five minutes the wind, now exceeding 20+ knots was ripping the tops off of waves in long strands of mare's tails. I reached the buoy and grabbed on to a huge eyelet welded onto its side. Another half mile and I could sneak in behind the islands flanking the channel along the town side of the bay. I vowed to check the weather report the next time I ventured out. Lesson learned.
You don't need a lot of equipment to be able to make fairly sound weather predictions - especially if you know a few basic principles and can read the local skies (and often animal behavior and other physical signs). At least you should know when the meteorological yellow flag is waving.
Before getting into an overview of "weather", let's all make sure we're on board with the same definitions:Weather - the conditions and characteristics of the atmosphere at a given time
Climate - weather conditions over a period of years
Wind - the horizontal movement of air
Current - the vertical movement of air.
General definitions of cloud shapes/types are also handy, especially when trying to predict upcoming weather. First, we all know what a "cloud" is, but here is the technical definition: visible aggregate of minute particles of ice or water (< 100 microns).
In very general terms, the high clouds tell of upcoming weather - those ice crystals are from moisture in the air generated by distant storms often meaning fair weather further down range. Low clouds are generally a manifestation of current weather in the immediate area. The middle range clouds are indicative of the "weather" over a greater area or region.
- High clouds
Cirrostratus: thin veil of ice crystals (form a halo around sun)
Cirrocumulus: tiny cotton balls or rippled sand.
- Middle clouds
Altostratus: light gray veil that almost blocks the sun.
Altocumulus: lumpy, like a flock of sheep.
- Low clouds
Cumulus: puffy clouds
Stratus: straight, layered clouds
Stratocumulus: puffy clouds, clustered, not fully separated nor completely layered either.
Nimbostratus: dark clouds not usually visible from directly below
Air, Pressure, etc.
Changes in the air's temperature affects how it moves. Warm air rises forming a partial vacuum that creates a low pressure at the surface of the earth. That rising air begins to expand and get cold (often forms clouds). Conversely, as that air starts to sink again, it warms up and starts to pile up at the earth's surface thereby creating high pressure. Those shifts in pressure are measured with a barometer. Winds blow from high pressure to low pressure.
Lines of equal pressure around either a high or low area look like a contour map. Those lines are much closer together around a low pressure area. Since the air flows from high to low it flows from the wider contours to narrower ones, creating higher winds because of the steeper, downward slopes of those narrower contour lines. (See diagram).
Besides temperatures causing air to rise, obstructions on the surface do, too (i.e. mountains). Fronts are created when two air masses collide - the heavier, cooler air forcing the lighter, warmer air to rise up over the cooler, heavier mass.
Generally then, higher pressure means drier, warmer conditions; lows mean rain, winds, etc. Highs circulate winds clockwise; lows circulate counter-clockwise.
Here's a handy rhyme to remember what to expect from high vs. low pressure areas:Mother Nature's Weather Forecaster:Tighten a bolt, increase the pressure
Loose a screw, pressure is lesser.
Tighten it swiftly for fair weather wind,
Loosen it quickly, fierce storm to begin.- Don Haggerty "Rhymes to Predict the Weather"
Low pressure causes insects and birds to fly lower than with high pressure; bees tend to be more active before fair weather. A vertical column of smoke is a sign of fair weather whereas smoke that tends to flatten out indicates poor weather. Odors are more noticeable and sound seems louder and sharper in low pressure air. Here's another rhyme to help you predict the weather:Halos around the moon and sun are also good indicators of impeding weather. A halo or "sun dog" usually means rain before the night is done. A "moon dog" can mean rain by the following noon. Sharp, clear images of the moon, and bright, twinkling stars means there is little moisture in the air.When the dew is on the grass, rain will never come to pass.
When the grass is dry at morning light, look for rain before the night!- Don Haggerty "Rhymes to Predict the Weather"
Of course, every school kid is taught: "Red sky at morning, sailor take warning. Red sky at night, Sailors delight!"
Red skies means there's dust in the air to the west. This is a sign of dry air that's coming at you (red sky at night). However, if you are looking through a red sky to see the morning sun, that usually means the dry air has passed over perhaps being pushed by moisture laden air over you.
Like several of these weather elements, entire chapters are typically written about wind. From a safety standpoint, knowing all the ways winds can be generated is important. We've already discussed how temperature, obstructions and other weather elements affects the movement of air (wind). From a boater's perspective here are few types of winds that can have an adverse affect on you.
Anyone paddling where there are high, sheer bluffs, cliffs or steep mountains adjoining the water's edge should be aware of williwaws. These are winds that literally spill down off of the high country like water overflowing a sink. A basin high in the mountains fills with cold air to overflowing. That air then spills over and rushes down the side of the mountain or down over the cliff and out across the water. These sudden gusts can come out of nowhere and cause an unsuspecting and unready kayaker to capsize.
Surges can occur when high winds push high waves inland. This can create dangerous surf zones as well as damage to tidal areas on shore. Checking tide tables and watching the weather and wind build will help you be on the watch for surges.
Remember, too, that during the day, as the sun heats air over land, the sea is cooler. This causes the cooler, sea air to flow in to replace the rising, warm air over land. At night, the land cools faster than the ocean and the wind shifts to flow back out to sea.
Whatever wind confronts you, its good to know its relative speed, perhaps to make some course alterations or trip decisions. The Beaufort Wind Scale is an old mariner's chart developed a couple hundred years ago to determine wind speed based on 12 stages of wind velocity as it affects waves and objects on land (bending trees, waving flags, etc. - see table at end of article).
Learning weather signatures and what to expect will help you make safer decisions when it comes to planning on on-water activities, course selection and alternate planning needs. A good marine-band weather radio is an essential piece of equipment for even an afternoon on the water. Smaller, wristwatch-sized compasses with a barometer are also a good bet, especially those that will track readings in eight-hour segments to show changes in rate and amount of change in pressure. Be a weather savvy kayaker!
Beaufort Wind Scale
(table courtesy of NOAA's Storm Prediction Center www.spc.noaa.gov/)
Appearance of Wind Effects On the Water On Land 0 >1 Calm Sea surface smooth and mirror-like Calm, smoke rises vertically 1 1-3 Light Air Scaly ripples, no foam crests Smoke drift indicates wind direction, still wind vanes 2 4-6 Light Breeze Small wavelets, crests glassy, no breaking Wind felt on face, leaves rustle, vanes begin to move 3 7-10 Gentle Breeze Large wavelets, crests begin to break, scattered whitecaps Leaves and small twigs constantly moving, light flags extended 4 11-16 Moderate Breeze Small waves 1-4 ft. becoming longer, numerous whitecaps Dust, leaves, and loose paper lifted, small tree branches move 5 17-21 Fresh Breeze Moderate waves 4-8 ft taking longer form, many whitecaps, some spray Small trees in leaf begin to sway 6 22-27 Strong Breeze Larger waves 8-13 ft, whitecaps common, more spray Larger tree branches moving, whistling in wires 7 28-33 Near Gale Sea heaps up, waves 13-20 ft, white foam streaks off breakers Whole trees moving, resistance felt walking against wind 8 34-40 Gale Moderately high (13-20 ft) waves of greater length, edges of crests begin to break into spindrift, foam blown in streaks Whole trees in motion, resistance felt walking against wind 9 41-47 Strong Gale High waves (20 ft), sea begins to roll, dense streaks of foam, spray may reduce visibility Slight structural damage occurs, slate blows off roofs 10 48-55 Storm Very high waves (20-30 ft) with overhanging crests, sea white with densely blown foam, heavy rolling, lowered visibility Seldom experienced on land, trees broken or uprooted, "considerable structural damage" 11 56-63 Violent Storm Exceptionally high (30-45 ft) waves, foam patches cover sea, visibility more reduced   12 64+ Hurricane Air filled with foam, waves over 45 ft, sea completely white with driving spray, visibility greatly reduced
"Rhymes to Predict the Weather" by Don Haggerty (Springmeadow Press; May 1985)
Texas Parks & Wildlife Department (www.tpwd.state.tx.us/)
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