Variable April Weather Affects Snow Melt
Ron Abramovich, Water Supply Specialist
For More Information:
Jeff Anderson, Hydrologist: 208.378.5740
Phil Morrisey, Hydrologist: 208.685.6983
Boise, ID, May 9, 2012 – The May 1 Water Supply Report from the Natural Resources Conservation Service documents the variability of April’s snowpack, precipitation, and streamflows across the state. However, adequate water supplies are predicted for this irrigation season.
“Nearly all of Idaho’s major reservoirs are storing average or better levels for May 1,” said for NRCS. “High inflows are keeping reservoir managers on their toes to mitigate flood impacts while maintaining adequate space available for future flows.”
According to Abramovich, rain in March helped ripen mountain snowpacks causing snow melt to start in early April. Warm temperatures across the west in late April produced record melt rates of up to an inch per day. “Even some of the higher elevation sites started melting nearly a month early,” he said.
The hot spell was followed by 1-2 inches of rain and the resulting runoff caused rivers to rise to record April levels across Idaho. April streamflow volumes ranged from 150-275% of average for over half of the streams NRCS monitors in Idaho. The rapid increase in streamflows has caused reservoir managers to make flood control releases to maintain space in their reservoirs. As of May 1, there is still enough snow in the higher elevations across central and northern Idaho to produce another increase in flow when warm temperatures return.
For more information about snowpack, precipitation, runoff and water supplies for specific basins, please view the complete May 2012 Water Supply Outlook Report online at www.id.nrcs.usda.gov/snow and click on the ‘Water Supply’ link.
NRCS conducts snow surveys at the end of each month from December through May to make snow runoff predictions and water supply forecasts used in managing Idaho’s water resources.
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