Kevin Myatt is The Roanoke Times' weather columnist.

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A few of you here and there may be seeing a few snowflakes floating through the air this morning.

A familiar pattern for snow showers has developed, with cold, northwest winds blowing over the mountains. As the winds lift what little moisture is in the air up the western side of the mountains, clouds and snowflakes condense in the colder air aloft.

This upslope snow pattern repeats itself many times in a typical winter. It is largely the reason places such as Snowshoe and Canaan Valley in West Virginia usually collect many feet of snow even in a mild winter. The Great Lakes help feed moisture to those higher elevation areas.

Areas of southeastern West Virginia and the far southwest corner of Virginia near Tazewell can get several inches of snow off upslope situations in the winter. Mountain Lake and Potts Mountain to the west of us can be turned into winter wonderlands during a strong upslope event.

At best, most of the New River Valley might get an inch or two in a strong upslope event, and the Roanoke Valley might get a dusting. Usually, the valleys get only flurries from such an event. As winds descend the eastern side of the mountains, they dry out.

With this one, most of the snowflakes will stay to the west of Interstate 81. Conditions are marginal, so lower elevations might not see any snowflakes, and even higher elevations are not likely to get much accumulation.

Besides upslope flow, there are three basic kinds of weather systems that bring accumulating snow to Southwest Virginia.

The first is a low-pressure system moving from the northwest called an "Alberta clipper." These are usually fast moving and fairly weak. Most either fail to bring adequate moisture over the mountains or take a track to the north of us.

A few dip far enough south and remain strong enough to bring substantial snowfall. The only widespread snowfall of last winter in early February resulted from an Alberta clipper.

The second is a low-pressure system crossing the southern United States. If the system stays far enough south, allowing cold air to remain in place, it can sweep enough Gulf of Mexico moisture in to bring snow to our area.

A lot of our medium-size snows -- those 4- to 8-inch type snows -- result from these southern track storm systems. There's always a fight between air masses, and the right balance is essential to getting a decent snow.

Too much cold, dry air from the north can squelch the necessary moisture and leave us snowless. Too much warm, moist air from the south can turn everything over to sleet, freezing rain or rain.

The third is an Atlantic coastal storm. Most of these begin as a southern-track low pressure system and then intensify and move up the coast.

If a coastal storm intensifies early enough and far enough to the south, it can sweep tons of moisture from both the Gulf and the Atlantic into deepening cold air it helps pull south from Canada, and a large snowstorm can result in our area.

This kind of system is what gave us our big 1- to 2-foot snowstorms of 1993 and 1996. In recent years, we've had amazingly few coastal storms affect us in winter. A widespread 6- to 12-inch snow on Feb. 28, 2005, is the last time I can remember our area having a fairly heavy snow from a coastal storm.

Snow is definitely the most popular subject I cover in my columns and on the weather blog, as evidenced by the number of e-mails and Web site visits I receive.

So consider this a winter storm primer as we move closer to the snow season, however much or little it may bring.