Weather for ’99: wet and dry
The weather was frightful in 1999.
The Aspen-area snowpack was below average in every month of the ski season, but overall precipitation for the year was well above average due to summer rains. All this made for less-than-desirable conditions for tourists and locals looking to recreate.
Two Aspen records were set in 1999 – one for wetness and the other for dryness. According to figures from the Aspen Water Department, November 1999 had the least precipitation of any November on record, with 0.42 inches. The previous low was 0.63 inches, observed in 1959.
And a record for the most rain in a half-hour period was set Aug. 26, said veteran local weather watcher Jim Markalunas. His rain gauge, which has a two-inch capacity, overflowed in a half-hour deluge, he said. During the same period, a gauge at the Water Department recorded .98 inches. And with an official 3.64 inches of rain in August, the month was the wettest August since 1964.
Though the lack of winter snow made a dent in the number of skier visits, the summer rains didn’t seem to hurt Aspen’s lodging business. Patti Hecht, public relations manager for the Aspen Chamber Resort Association, said on every weekend from July 4 through the end of August, hotels and lodges were full. ACRA figures indicate overall lodging occupancy in July was at 83 percent of capacity, and in August it hit 80 percent.
Hecht guessed that the rain may actually have increased occupancy, bringing indoors some of the visitors who had intended to camp out.
“They may not have been out there hiking and biking as much,” she said.
Bob Jacobson, a meteorologist for the National Weather Service in Grand Junction, said in general, the greatest effect on Aspen’s 1999 weather was exerted by La Nia, a worldwide weather phenomenon which alters air flow patterns and ocean currents.
The American Southwest tends to be drier in a La Nia year, and that certainly was true for both the winter of 1998-99 and the current season. But summer’s persistent rains were harder to explain.
The “Bermuda High,” a high-pressure air mass which parks itself in the Gulf of Mexico in most years, is the key to the rains, Jacobson said. Normally, the high moves back and forth from east to west throughout the summer. As all high pressure masses do, it revolves in a clockwise direction, its western edge sending moist air from the Gulf into North America in what’s known as a monsoon flow. As the high reaches the western extreme of its range of movement, the moisture is pushed into Colorado’s Rockies.
But this year, for reasons unknown to Jacobson, the Bermuda High stayed to the west, continuing to pump wet air into Colorado. The resulting monsoon rains lasted all summer long.
This continuing rain was responsible for the above-normal annual precipitation total that was recorded in spite of snowfall that was consistently below average. Figures kept by Markalunas indicate total precipitation for the year was 119 percent of average.
Mike Gillespie, snow survey supervisor for the U.S. Natural Resources Conservation Service, said the snowpack in the Roaring Fork Valley started 1999 at 58 percent of the average depth for Jan. 1, and remained below normal in every month of the year in which measurements are taken.
The level was at 61 percent of normal on April 1 and big storms which moved in after ski areas closed in April could not drive the level up to normal. Gillespie’s agency measures the snowpack in the Roaring Fork drainage at six stations throughout the valley.
The snow drought set in again in the fall and early winter of 1999. And this winter has been even less productive than last, in terms of early snowfall. On Jan. 1, 2000, the snowpack in the Colorado River basin was 56 percent of average. Roaring Fork Valley figures were not yet available.
What’s different about this winter is there were no wet snowstorms in October and November to provide a base for later, drier snow, both on the ski areas and in the backcountry.
“We didn’t get a good base,” Markalunas said. “Without that, you’re not going to have good conditions.”
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