10/19/07 La Nina and its potential impact

Wet weather has come to Idaho and more may be on the way. Forecasters say a La Nina weather system is forming in the eastern equatorial region of the Pacific Ocean. Normally that means Idaho and the Northwest should receive above normal winter rain and snowfall says Ron Abromovich of the NRCS Snow Survey group. ABROMOVICH "Overall if you looked at La Nine years it increases the winter precip by about six percent across the Pacific Northwest." Regions like the upper Snake River have no carryover water in the reservoirs and irrigators can only hope for an above normal snowpack. ABROMOVICH "We really haven't had good runoff in the upper Snake since 1999. In 2006 we had normal runoff. This past year 2007 the runoff was only about 54 percent of average." For adequate irrigation needs Abromovich says the Boise River basin needs an 85 percent of normal snowpack next April first to provide a 70 percent of average runoff or stream flow. The Big Wood reservoir is nearly empty and will need 136 percent to produce a 110 percent stream flow. Little Wood needs 78 percent snowpack next April, the Big Lost basin needs 110 percent, the Little Lost needs 122 percent and the upper Snake needs 112 percent of average and that would overcome a dry spring, should that happen. Now we wait to see if La Nina kicks in and brings badly needed moisture. Today's Idaho Ag News Bill Scott