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The last two months (February, January-February) have been extremely dry across parts of Idaho.
Below-normal precipitation and above-normal temperatures during the last three months have resulted in extensive snowmelt in the Idaho mountains. As noted by the USDA Natural Resources Conservation Service (NRCS) (Ron Abramovich), record low snowpacks dominated northern Idaho at the end of February, drier even than the record dry winter of 1976-77. Snowpacks ranged from less than 50% of average in the northern parts of the state to 70-85% of average in the south and east. Due to well below average precipitation through February, the water supply outlook in Idaho deteriorated during the month, with the Surface Water Supply Index (SWSI) in the -2.5 to -4.0 range (severely to extremely dry) in most basins. (The SWSI is an index that integrates snowpack, reservoir storage, streamflow, and precipitation at high elevation as a measure of surface water status.) Streamflow forecasts were in the 35-65% of average range. An analysis of the state's reservoirs by the USDA NRCS (Tom Pagano) showed that reservoir storage was below average across most of the state except for northern Idaho. A report by the USDA NRCS on February climatic conditions in Idaho is available from:
The record and near-record March 1 snowpack for automated mountain SNOTEL stations include the following, where the 3/1/05 snow water equivalent (inches of moisture), the difference compared to the previous (3/1/77) low record, and the length of record are listed:
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Cool Creek 2005 20.0 (-0.9) 45 years
Elk Butte 2005 13.5 (-1.8) 45 years
Humboldt Gulch 2005 1.8 (-4.4) 58 years
Lookout Pass 2005 9.3 (-0.6) 64 years
Shanghi Summit 2005 6.6 (-2.9) 47 years
Sherwin 2005 2.8 (-1.3) 48 years
Sunset 2005 9.1 (-4.0 est) 75 years
Three manual snow courses also set new record low snow water equivalent observations for the period of record. These include the following (this is the first year that the Moscow snow course did not have snow on March 1):
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Kellogg Peak 7.8 67 years
Moscow Mountain 0.0 49 years
Crooked Fork 4.5 45 years
As reported by the National Weather Service, Boise had the driest 2-month period for January-February with only 0.57 inch of precipitation.
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NCDC /
Clim. Monitoring /
Climate-2005 /
Feb /
U.S. Regional Drought /
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