Keeping Up With the Clouds
By Gregg Fauth, Park Ranger

The weather at Crater Lake is interesting and impressive. Large snowbanks lasting into August definitely catch your attention. And everyone has their idea about what is "normal" when it comes to yearly rain and snow. Much of the literature about Crater Lake and its "averages" has become dated and inaccurate. Recalculating the records shows large changes in what we consider average.

Annual precipitation averages are recomputed yearly on Dec. 31, the end of the precipitation year. Using the 57 years we have weather records from since 1930 (all taken at park headquarters), the figures reveal that the park's average precipitation is 66 inches. This average is three inches below the 69 inches reported in most literature.

Yearly snowfall averages are recomputed at the end of the snow year, July 1. Beginning with the winter of 1930-31, and ending with 1991-92, the yearly average for accumulated snowfall is 528 inches, taken from 58 years of records. This average divides out to 44 feet. These new figures for snowfall are significantly below the 600 inch and 50 foot figures that have been tossed about so often. In Mid-May 1992, the averages changed again. The winter of 1992-93 has seen some 600+ inches fall, which will raise the average back up to 529 inches.

We need to keep reminding ourselves that weather, like other natural phenomena, is constantly changing and does not fit into neat, everlasting pigeonholes. These dynamic systems make today's "facts" become tomorrow's "stories".

Record High Snowfall: 1932-33: 879 in., 1952-53: 835 in.
Record Low Snowfall: 1991-92: 243 in., 1930-31: 277 in.

Why Does Crater Lake Get So Much Snow?
The major weather patterns in the park originate in the Pacific Ocean. Storm events originate in the north Pacific and build in strength and moisture while over the ocean. Wind patterns at these northerly latitudes move storms from the ocean to the Pacific Northwest. Over 100 inches of rain falls each year on the Oregon Coast. The Rogue and Willamette valleys receive about thirty inches of rain as the moist air descends and warms. This advancing moist air cools greatly as it encounters the Cascade Range. These high mountains push the warm moist air to elevations over 10,000 feet. This change in elevation cools the air and hastens the precipitation process. As warm moist air rises, it cools. Water vapor in the air condenses to form clouds. If there is enough moisture in the clouds, rain is produced. If the temperature is low enough, this precipitation freezes into snow.

The most snow ever reported on the ground in the park was 21 feet on April 3, 1983. The snow pole at park headquarters records the official depth of snow on the ground. Each time it snows in the park, we measure the new snowfall and keep a running total. For the past five years that amount has been in the 430 inch - or 36 foot - range. This is quite a drop, however, since the early 1900's when the average was 533 inches or 44 feet of snow annually.

Keep in mind that the park's weather doesn't stop at our boundaries. The ocean borne winds that bring us snow and rain, although drained of much of their moisture, continue to eastern Oregon, usually dropping what little rain remains. Each area of this state reflects its precipitation. The Cascades collect snow and rain which sculpt rock and create subalpine and alpine environments. If you visit the park in summer or fall, try to imagine 21 feet of snow blanketing everything. Then envision spreading phlox covering the roadsides. Without the snow, there would be no phlox, no streams, and ultimately, no Crater Lake.

Back to the Climate of Crater Lake