The late February/early March period is the safest part of the season in terms of coverage/conditions at most resorts. Jackson is probably the only one where preservation is a concern this early, and there are a handful of low snowfall areas where "wait until the season starts" is always the best advice. But in general it will take bad luck to produce lousy conditions at this time and you should choose your resort for the terrain/ambience you prefer.
Whistler's conditions this year were an extreme event. It is the only such year in 30 years of records. Even in the widespread drought year of 1976-77 Whistler was in good shape from mid-February onwards, and in nearly all other cases it was well covered before Christmas.
Last year's El Nino was weak, and the consistent southern storm track was coincidental. A meteorologist friend recommends the following site as best tracking of El Nino intensity: http://www.cdc.noaa.gov/people/klaus...MEI/table.html
According the this table 2004-05 ranks only 14th in El Nino bias out of the past 55 years, and more relevantly the strength was only about 1/4 of the strong ones in 1982-83 and 1997-98.
El Nino or La Nina will be strong enough to influence advance ski planning maybe 10-15% each, and not all areas are significantly affected. See updated excerpt from my skiingmag.com article below:
La Niña increases snowfall by about 20 percent at most areas north of Utah and California, so we recommend early season bookings in Canada, the Northwest and northern Rockies during predicted La Niña seasons. Snowfall is reduced substantially in Southern California and Arizona, but only mildly (10 percent or so) at Mammoth, Brian Head, and in New Mexico.
El Niño predictions are less helpful to skiers. The positives are in the same locations that are negative for La Niña (plus Tahoe), but the extra snow tends to be late in the season with negligible impact upon early-season reliability. Only in interior Canada and Montana is El Niño snowfall reduced as much as 10 percent. The Pacific Northwest may see more low altitude rain, but there is no decrease in snow in higher locations such as Mt. Bachelor and the Whistler Alpine.
Long-term data shows no significant El Niño or La Niña trend in Sun Valley, Utah, Colorado, or the Northeast.