the two winters is presented. The winter of 1977-78 was one of the 

 most severe in the past 100 years and it will be remembered pri- 

 marily for its deep snow and length of time that this snow re- 

 mained on the ground. The following weather data were obtained 

 primarily from the data collected at the Roy 8NE , official U.S. 

 Weather Bureau station, about 12 miles south of the eastern end 

 of the study area (U.S. Dept. of Commerce 1977-78). Temperatures 

 were not extremely severe; however, they were still below normal 

 for four continuous months (November through February) . Snowfall 

 commenced on November 19, 1977 and for the next 128 days (until 

 March 27, 1978) snow was recorded covering the ground. Snow 

 depths averaged about 6 inches in November and increased to 19 

 inches during the first two weeks of December. Snow levels 

 dropped to 2 inches for 1 week and then increased to 20 inches on 

 December 31. From December 31 through March 2 5 (85 days) , there 

 were 20 or more inches of snow on the ground. From January 8 

 through March 21 (72 days) , there were 30 or more inches of snow 

 on the ground. From January 27 through March 16 (49 days) , there 

 were 36 inches or more and from February 11-20 (10 days) , there 

 were 50 or more inches of snow on the ground. On February 19, the 

 maximum snow depth of the winter, 56 inches, was recorded. 



The winter of 1978-79 was another severe winter, and accord- 

 ing to the U.S. Weather Bureau, it was the first time since 

 record keeping was started that Montana experienced two severe 

 winters back-to-back. The following weather data were obtained 

 primarily from the Roy 8NE, U.S. Weather Bureau station, U.S. 

 Department of Commerce 1978-79. The 1978-79 winter started No- 

 vember 9, 1978, 10 days earlier than the 1977-78 winter. It had 

 much deeper snow depths in November and December than the 19 77-78 

 winter; however, during January, February and March the snow 

 depths of the 1978-79 winter never reached the maximum depths or 

 remained there for as long a period of time as they did in the 

 1977-78 winter. Snow depths during the 1978-79 winter reached 

 18 inches in November, increased to 26 inches by mid-December, 

 dropped to 18 inches by December 31 and increased to 30 inches in 

 January. In February, snow depths varied between 23 and 31 inches 

 and by the second week of March they dropped to 10 inches. The 

 major thrust of both winters was over about the same time, the 

 third week in March; however, during the 1978-79 winter, below 

 average temperatures and above average precipitation in April 

 kept snow on the ground until April 25. The result was 167 con- 

 tinuous days with snow recorded on the ground at Roy, while the 

 1977-78 winter had only 128 days. The 1978-79 winter recorded 

 20 or more inches of snow on the ground for 65 straight days, 

 January 2 - March 7. Between January 23 and March 4, snow depths 

 reached 29 or more inches on 30 days. Maximum snow depth was 31 

 inches, recorded on February 14, and it remained at that level for 

 11 straight days. Temperature averages were below normal for 

 4 months (November through February) in the 1978-79 winter, the 

 same as 1977-78; however, the 1978-79 winter was colder each 

 month, November through February, than the 1977-78 winter. 



