El Nino has its most direct effect upon areas close to the equatorial Pacific. South America had a huge 1997 ski season, with big dumps beginning in May and a 10 foot base reported in most Chilean resorts by mid-July. Conversely, Australia and New Zealand had essentially no snow before July 1, although snowfall since late July was near normal. The previous major El Nino of 1982 resulted in Australia's driest winter of the last 40 years.
The table below shows snowfall at North American areas during the previous major El Nino season of 1982-83. The most conspicuous results are the extremely high totals from California, which were hyped by our local weather reporters. El Nino raises temperatures as well as precipitation, so note that there was great divergence in snowfall between the higher and lower altitude areas of the Pacific Northwest. The Northeast had a poor season, and results from continental western ski regions did not seem unusual. Some researchers believe that a strong El Nino may influence the North Pacific jet stream and storm track to take a more southerly course than normal. However, the 1978-79 and 1992-93 seasons had consistent southern storm tracks and I never recall hearing El Nino mentioned as the reason. Another theory is that the jet stream is more likely to split, bringing high precipitation to Alaska and the Southwest and leaving a drought "hole" in between. There were a couple of split jet episodes in late fall and early spring of 1997-98, but this pattern did not dominate most of the season as in 1991-92.
My analysis of snow statistics led me to be cautious in attributing a cause and effect relationship between El Nino and the numbers below. The California 1982-83 results and the 1997 Southern Hemisphere weather fit the theory, but two seasons do not constitute statistical significance.
Another recent analysis of El Nino drew the analogy to flipping a biased coin. All the random factors which affect weather are still there, but the chances of a southern or split storm track or greater intensity than normal are increased. There is still a reduced but significant chance that the expected events will not occur. Thus, when forecasters include milder El Nino episodes than 1982-83 in their analyses, the effects are much less clear cut.
In summary, the 1997-98 winter weather conformed to El Nino expectations during about a third of the snow season, but to such a strong degree that season snow totals reflect its influence. In considering both 1982-83 and 1997-98, I suspect the El Nino coin has its strongest bias in Southern California, with the influence declining gradually as one moves north up the coast and more rapidly as one moves inland.
There is a mild tendency for the North American storm track to be strongest in Canada in December and move south to Utah and Colorado by March. Therefore El Nino effects are more probable in the second half of the ski season (February to April) than the first half (November to January). 1982-83 snowfall was more consistent than we saw in 1997-98 but it was still stronger in the second half. It snowed in the Sierra every weekend from January 15 to May 15 in 1983. For more details on 1997-98, see 1997-98 Season Analysis and 1997-98 Ski Season Summary.
| 1982-1983 SKI SEASON SNOWFALL SUMMARY | |||||
| RECORD HIGH (10 Years Minimum) | RECORD HIGH (10 Years Minimum) | ||||
| Central Sierra Snow Lab - Boreal, Cal. 7,200 | 676 | Sun Valley, Idaho 8,800 | 232 | Dec.-Mar. | |
| Kirkwood (Carson Pass), Calif. 8,526 | 788 | ||||
| Southern California Composite 7,000 - 8,000 | 264 | ||||
| HIGH | HIGH | ||||
| Berthoud Pass, Colo. 11,315 | 362 | Squaw Valley, Calif. 6,200 | 352 | Dec.-Mar. | |
| Alta, Utah 8,650 | 630 | Teton Pass, Wyo. 8,000 | 254 | Dec.-Mar. | |
| Mammoth Mtn, Calif. 9,600 or 8,900 | 567 | Big White, B. C. 6,200 | 219 | Dec.-Mar. | |
| Mt. Bachelor, Ore. 6,350 | 536 | Sugar Bowl, Calif. 7,000 | 551 | Dec.-Mar. | |
| Loveland, Colo. 11,200 | 417 | Big Sky 1, Mont. 8,000 | 212 | Dec.-Mar. | |
| Snow Basin, Utah 7,700 | 409 | Crystal Mtn 2, Wash. 6,100 | 325 | Dec.-Mar. | |
| Alpine Meadows, Calif. 7,000 | 606 | ||||
| Arapahoe Basin, Colo. 10,820 | 418 | ||||
| ABOVE AVERAGE | ABOVE AVERAGE | ||||
| Taos, N. Mex. 11,200 | 304 | Vail, Colo. 11,250 | 261 | Dec.-Mar. | |
| Snowbird, Utah 10,000 | 538 | Copper Mtn, Colo. 11,000 | 210 | Dec.-Mar. | |
| Brighton, Utah 8,740 | 452 | Aspen Mtn, Colo. 11,190 | 181 | Dec.-Mar. | |
| Mary Jane at Winter Park, Colo. 10,800 | 393 | Red Mt. Pass, Colo. 11,090 | 256 | Dec.-Mar. | |
| Winter Park Base, Colo. 9,265 | 256 | Wolf Creek, Colo. 10,642 | 286 | Dec.-Mar. | |
| Whistler Roundhouse, B. C. 6,000 | 404 | Purgatory, Colo. 10,000 | 185 | Dec.-Mar. | |
| Park City 1, Utah 7,140 | 158 | Tod Mt. (Sun Peaks), B. C. 6,100 | 150 | Dec.-Mar. | |
| Arizona Snowbowl 1, Ariz. 9,500 | 215 | ||||
| Arizona Snowbowl 2, Ariz. 10,800 | 275 | ||||
| BELOW AVERAGE | BELOW AVERAGE | ||||
| Mt. Rainier Paradise, Wash. 5,420 | 581 | Crested Butte, Colo. 10,150 | 136 | Dec.-Mar. | |
| Stowe, Vt. 3,950 | 198 | Bridger Bowl, Mont. 7,100 | 181 | Dec.-Mar. | |
| Sunshine Village, Alb. 7,028 | 188 | Stevens Pass, Wash. 4,061 | 296 | Dec.-Mar. | |
| Mt. Norquay, Alb. 5,350 | 82 | Sunlight, Colo. | 151 | Dec.-Mar. | |
| Cannon Mt., N. H. 1,800 | 112 | Crystal Mtn 1, Wash. 4,400 | 208 | Dec.-Mar. | |
| Sugarloaf, Maine 3,695 | 138 | Snoqualmie Pass, Wash. 3,000 | 237 | Dec.-Mar. | |
| Jackson Hole, Wyo. 8,250 | 350 | ||||
| Gothic, Colo. 9,400 | 332 | ||||
| Alyeska, Alaska 1,400 | 477 | ||||
| Monarch, Colo. | 259 | ||||
| Blackcomb, B. C. 5,002 | 341 | ||||
| Thompson Pass (Chugach), Alaska 2,450 | 368 | ||||
| Lake Louise, Alb. 6,700 | 120 | ||||
| LOW | |||||
| Mt. Washington, N. H. 6,262 | 188 | Schweitzer, Idaho | 138 | Dec.-Mar. | |
| Killington, Vt. 4,241 | 197 | ||||
| Mt. Fidelity, B. C. 6,150 | 414 | ||||
| Whistler Base, B. C. 2,200 | 128 | ||||
| Steamboat, Colo. 9,200 | 232 | ||||
| Jay Peak, Vt. 3,000 | 247 | ||||
| Whiteface (Lake Placid), N. Y. 3,660 | 48 | ||||
| RECORD LOW (10 Years Minimum) | |||||
| None | |||||