More dry weather could spell trouble for the Big Wood Basin's water supply.
A report released Friday by the Natural Resources Conservation Service indicated that the overall state of the Idaho snowpack is good, with most regions ranging from 90 to 105 percent of normal. But the Big Wood Basin only received 25 percent of normal precipitation in January.
"We can get by with one month of below-normal precipitation, but if we have two or three, that's when we'll start getting concerned," said Ron Abramovich, water supply specialist for the NRCS.
According to the service, the dry weather has been caused by a high-pressure ridge that is preventing winter storms from reaching much of Idaho.
"Hopefully, the ridge will break down and we'll get more precipitation to help maintain the snowpack," Abramovich said.
Troy Lindquist, hydrologist with the National Weather Service, said high-pressure ridges such as the one over Idaho generally last 10 to 14 days. This one, however, has dominated Central Idaho weather patterns for most of January.
"We've had some periods when the ridge has broken down and rebuilt, but it strengthened at the end of January," Lindquist said.
That pattern could change as early as the middle of next week, when the ridge could shift farther west and drop Idaho into what Lindquist called a "trough" of low pressure.
This low pressure is currently sitting over the central and eastern United States, regions that have been pummeled by storms over the past month. Lindquist said the shift in fronts could bring more storms into Idaho.
That's good news for the snowpack and the water supply, as Abromovich said the health of both depend on the levels of precipitation this month.
"The Big Wood has a 50 percent chance of having an adequate water supply," he said.
Water stored in Magic Reservoir south of Bellevue is still above normal levels, but that might not last for long if February is dry. Abramovich said that if the basin doesn't get any snow between now and April 1, the snowpack could be down to 55 percent. Such a low level would impact agricultural and other users severely.
"That would not be good news at all," he said.
Katherine Wutz: email@example.com