Pilots and weather have had an uneasy relationship since flight began. Jack Williams, who wrote The Weather Book, produced by USA Today, says that weather has been implicated as a factor in 40% of all aviation accidents.

The weather factor most often sited when talking about accidents and incidents is wind. In aviation fatalities, fog and clouds, or instrument meteorological conditions is the prevailing factor.

In 1837, the invention of the telegraph made weather-forecasting services possible. Telegraph networks encouraged widespread observations. Most scientific effort went into describing weather and the apparent connections among meteorological events. In the 1920s and 1930s, scientists lead by Vilhelm Bjerknes, developed a "picture" of the atmosphere and forecasting methods based on the laws of physics. Newton’s Laws, worked out in the 1700’s were now being applied to weather.

There are three types of forecasts: Persistence, Climatological, Meteorological.

Persistence forecasts are based on the concept that future weather will be the same as current weather. Good only for an hour or two, they are especially unreliable if the weather is poor and or changing at the time of the observation.

Climatological forecasts use average weather of a particular region. This works, for instance in predicting that there will be no snowstorms in Los Angeles in July.

Meteorological forecasts use scientific knowledge of atmospheric processes. Using mathematical equations to predict the weather is an essential component of modern meteorological forecasting. The equations represent the physical laws governing the behavior of the atmosphere. Large numbers of calculations are involved. The National Meteorological Center uses a super computer capable of 2 billion calculations per second.

Keep an eye on the big picture of weather daily either by checking out the newspaper weather page, watching weather on TV or making it a favorite when you go into the web.

If your planned flight is a few days into the future, check out satellite imagery and large scale forecast maps. Look mostly to the west for what’s coming. If you are planning a long distance flight, look upwind from your route of flight and take stock of the terrain you’ll be flying over. The upper air patterns and that terrain will interact to shift the weather a little or a lot.

Call your Flight Service Station (1 800 Wx Brief) for an outlook briefing about 12 hours before your planned departure. It’s a great way to talk to a seasoned professional and get questions you may have, answered. The Flight Service Station (FSS) is one of the most precious resources we pilots have today. Visit a FSS, it’s an investment in your safety.

Use the web, DUATS, or any commercial site for charts and graphs. Get a standard weather briefing from the FSS an hour or two before the flight, and if conditions are changing, get an update just before take-off.

While flying, watch for unexpected weather and get updates from flight watch on 122.0. Support your fellow pilots with pilot reports. Do that on 122.0 as well.

Several of the safety meetings this month will address the use and interpretation of specific weather products. Find one near you, you’ll get great information and have a good time as well.

Kathleen O' Brien, SPM, LGB FSDO

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