EYE ON THE SKY

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There are also fairly predictable cloud sequences that cold and warm fronts follow.

Cold front sequence:
Cirrus
Cirrocumulus
Altocumulus
Stratocumulus
Cumulonimbus (summer)
or nimbostratus (winter)
Warm front sequence:
Cirrus
Cirrostartus
Cirrocumulus
Altocumulus
Nimbostratus or cumulonimbus
Stratus

Now that both clouds and pressure systems are part of our vocabulary, we can get to more complete forecasts while examining a sky with different cloud types. Though the general rules below are not guaranteed, they will go a long way towards giving you an edge.

As a general rule, fair weather comes from the southwest in summer and the northwest in winter, but it's helpful to know the prevailing wind in your locale. Watch for change. If the wind shifts counterclockwise between the south and the northeast, there's likely to be bad weather within the next 24 hours. Likewise, if the wind shifts clockwise from between the south and northeast to the west, the weather will likely improve.

You can be slightly more exact by determining the low-level wind direction. Stand with your back to the lower wind (not always the wind at the surface, but rather the direction that low clouds are moving in). If the upper wind (direction of upper clouds) comes from the left, you are probably in for bad weather. If the upper winds blow from your right-hand side, the weather is probably taking a turn for the better. If the upper and lower winds blow in the same general direction, conditions will remain the same.

But what if there are no clouds to observe? Very educated guesses can still be made under those circumstances, as long as you know from what direction fair weather winds generally blow in your area. If the wind shifts counterclockwise to the south or the northeast, stormy weather will probably arrive in the next 24 hours. Conversely, if the wind shifts clockwise from the south or northeast to the west, clearing conditions are on the way.

The only essential equipment needed to apply these rules are your glasses and a compass, but as your interest in local conditions grows, a good barometer, thermometer and wind meter will flesh out the picture considerably. A good rule of thumb in barometer watching is that when the meter rises or falls eight to ten millibars or more in less than three hours, a major change is in the works.

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