The big guns have commenced firing in the perennial battle between East and West--and that's no snow job.

To a flatlander, East-West conjures up classic conflicts: communism and capitalism, Migs and Minutemen. To the skier, the geographic phrase means Maine versus Montana and Vail versus Vermont. Mountains are more important than MX missiles, skis more critical than silos.

The battle has been raging since 1935 when Averell Harriman, then chairman of the board of Union Pacific Railroad, turned a "Godforsaken field of snow" into Sun Valley, Idaho, the first "destination" ski resort in the Rocky Mountains. Trains were soon carrying easterners off to the American Alps where Sawtooth slopes of dry powder won the hearts of skiers accustomed to icy Appalachian trails.

The western ski life was grand. Perfect weather. Perfect snow.

Perfect until five years ago, when two severe snow droughts -- one in 1976-77 and then one last year, 1980-81 -- nearly turned the Rockies into a brittle rockpile. Some resorts, such as Breckenridge, were forced to shut down for part of the season. Colorado, the captain of the ski industry, lost $95 million.

In 1979-80, eastern resorts were socked with the same malady. If not for artificial snow machines, it might have been Apocalypse Snow. The 1980-81 season could be described in two dirty words -- warm and wet.

Overall, according to the National Ski Area Association, business at the nation's 1,000 ski areas fell by an average of 21 percent last season, although business improved in the southeast.

Against that dreary backdrop comes an optimistic ski industry with both sides -- East and West -- fighting for the faithful.

"Advance bookings are super," said Foster Chandler, Killington's director of marketing, whose enthusiasm is sobered by inflation and the recent downturn: "Fuel, electricity, machine and tool parts, the cost of equipment, vehicles -- the ski area costs have gone up a lot higher than the rate of inflation. A lot of ski areas are in trouble."

One medium-sized resort, Vermont's Roundtop Mountain, was driven into foreclosure in October.

Out West, the watchword is caution. Peggy Lamb, a spokesman for Colorado Ski Country USA, a Denver-based consortium that represents the bulk of the state's resorts, said non-holiday reservations are slow. Nevertheless, like most industry officials, she predicts a great season. "Our time has come. America is going back to the real West," she said, and President Reagan is their leader. "It's a fashion, a fad, an overall feeling. We've got real cowboys; we don't have to make it up."

(What they may have to make up is snow. American resort owners spent $40 million in 1980 on snow-making equipment. Hard-hit Colorado bought more than half of the artificial snow machines.)

Scott Van Pelt, Lamb's counterpart at Stowe in Vermont, thinks it's all downhill for the East, where warm hotels with stone-hewn fireplaces answer western condos. Speaking for easterners once jealous of the West's glamor image, towering mountains and dry snow, he said, "We thought of ourselves as a second sister. But we don't have to take a second seat to anyone." The reason, he said, is economics.

With the East's dense population centers of Boston, Philadelphia and New York, Van Pelt said driving to Killington or Sugarbush is cheaper than flying to Jackson Hole or Aspen. Westerners, especially the California crowds, face similar considerations: driving to the Sierra Madres from Los Angeles could be considered pennywise compared to cost of flying to Utah's Park City or Snowbird.

Either way, it's going to cost the skier more. Al Greenberg, editor-in- chief of Ski magazine, predicts an 8.2-percent increase in the overall cost of skiing, after adding up price hikes for energy, transportation, lodging, lift tickets, equipment and food. (Killington's Chandler calls that estimate "conservative.") But skiing, noted Greenberg, "has never been a sport for the urban poor."

"Of course you pay more. You pay more for hamburger this year than last year," said Candy Moot, representing the Vermont Ski Areas Association.

In Aspen, lift tickets are going up by $2 to $4, a trend throughout the country. The cost of lodging can vary from a $50 a night at a hotel to $450,000 for the deed to a condominium at the only new ski resort opening this year, Colorado's Beaver Creek.

Whether the skier is bound for the gorges and glades of the Rockies, or the eastern moguls and bowls, one industry spokesman insists this is a buyer's market in a field that grew 46 percent from 1973 to 1979, according to A.C. Nielsen.

David Ingemie, the executive director of Ski Industries America, a Virginia-based trade association for manufacturers, said skiers will benefit from anxious airlines, resorts fighting for patrons, a glut in the inventory of skiing gear and the improved quality of skis, boots and bindings: Ingemie said injuries decreased 56 percent from 1976 to 1980. "There is an average of one injury per thousand skier-days. You literally have less chance of being injured while skiing than walking down the street."

The major cost of skiing, everyone agrees, involves lodging and transportation. Traditionally, United Airlines and TWA have vied for the lion's share of the ski traffic, even though TWA dropped out of the competition last year. For 1981-82, however, TWA is again pushing hard for skiers seeking a Rocky Mountain high at Steamboat, Ski the Summit, Taos or Santa Fe.

For instance, a skier leaving Washington, D.C., bound for a week's stay in Colorado, can fly round trip for $231 Monday through Thursday. The reduced fares are available only for skiers who buy a ski and lodging package -- in advance -- that includes lodging, lift tickets and food. A week's stay, during the off-season, at the Applejack Inn in Aspen is $389 per person -- double occupancy.

TWA said advance bookings are brisk, especially for the period around the end of February and in early March at hot spots such as Keystone, Colo., another area that invested heavily in artificial snow-making. This marks the first season that Keystone can blanket its 11,640-foot mountain in "fake flakes."

As a ski vacation bonus, TWA will throw in a free "skierized" rental car for seven days, furnished with ski rack and radial tires.

United Airlines is entering the fray on Jan. 5. From that date until March 25, Monday-through-Thursday travelers can fly round trip from Washington to Denver for $263. It's a five- to seven-day plan. Weekend fares jump to $392, but one can stay up to 60 days. Again, the reduced airfares are available only as part of a package. It's tailored to the five- or seven-day traveler.

In the eastern corridor, for example, the new brochure for Sugarbush Valley in Vermont offers a sample $250 round trip airfare from Washington to Burlington. On the ground, a five-day package of unlimited skiing, accommodations at a skiside hotel, lessons, entertainment, breakfast, a $15 credit toward dinner, all taxes and gratuities, plus membership at the Sugarbush Sports Center, costs $449 per person, double occupancy, Sunday through Friday -- not including holidays.

For the frugal and aerophobic, bus and train packages are available. Sea and Ski Travel in Maryland features a five-day stay at Sugarbush, including lift tickets, bus rides and two meals a day for $375. "If you go with a group, it's so much cheaper," said Shelly Sealock.

Amtrak carries a steady stream of skiers to New England, Canada and the western states.

Clearly, the East versus West lines are drawn. Chan Weller, the Sugarbush marketing director, thinks the East will win -- not because of the weather, but in spite of it.

"The eastern ski areas are miles and miles ahead in their ability to make snow and maintain decent snow cover," said Mill Moore, ski operations manager for the New England Ski Areas Association. "I'm not here to make invidious comparisons between East and West . Overall, their mountains are higher, but our vertical drop is the same on the average." (Jackson Hole, Wyo., has the highest vertical drop in the West: 4,139 feet. In the East, Killington is the steepest at 3,060 feet.) "We have the same number of lifts and trails. It's very subjective. Of course, I'm biased toward the East."

Regardless of destination, Moore encourages skiers to follow a cardinal rule: Get in touch with the lodging associations or chambers of commerce and quiz them on the packages. "It's confusing and takes time but it's worth it. There's such a profusion of package deals that you can really cut the per-day cost of skiing."

Of course, Europe is always an option, and the increasing strength of the dollar is enticing for foreign travel. But Canada should not be overlooked. The American dollar is worth 15 to 20 percent more than the Canadian dollar and the skiing is much the same: dry, powdery snow on expansive mountains ranges in the west and wet snow and old lodges in the east.

The final and most important factor rests with Mother Nature. For what it's worth, New Englanders pointed out this fall that the moss was thick on the backside of trees, the mice were so fat that barn cats were full of fear, and woolly bear caterpillars were luxuriating in thick coats.

Moreover, the Farmer's Almanac predicts that "snowfall at higher elevations will be greater than usual."