Posted: Feb 8, 2013 2:49 PM by Meteorologist Mike Heard
Bozeman--Snowpack finished January down slightly, 96 percent of median compared to 103 percent of median on Jan. 1, according to snow survey data from the USDA Natural Resources Conservation Service (NRCS).
Two major storm events provided the bulk of the moisture during the month of January, but only produced 85 percent of median snowfall for the month. The Headwaters of the Missouri and the combined St. Mary and Milk River basins hold the best snowpack of the major basins in the state at 103 percent of median. The Yaak, Beaverhead, and Upper Gallatin (above Gallatin Gateway) river basins maintain the best snowpacks of all sub-watersheds in the state at 113 percent of median or better.
The orographic effect of the Bridger Mountain range, better known locally as the "Bridger Cloud," produced large amounts of snowfall from a late January storm. Nearly two inches of snow water equivalent were measured at the two SNOTEL sites in the Bridger Mountains from the three-day storm. This amounted to a 23 percent increase in snowpack over the three-day period.
"Although other basins across the state benefited greatly from this same storm, snowfall yields were not as significant," said Brian Domonkos, NRCS water supply specialist. "Despite this and a smaller weather event earlier in the month, conditions were generally quite dry last month allowing snowpack to make increases in only two basins, the Headwaters Mainstem near Helena and in the combined Smith-Judith-Musselshell."
Typically on February 1, nearly 65 percent of the average seasonal snowpack has accumulated, meaning approximately one third of the snowfall season remains.