PORTLAND, Ore. (KOIN) – Mountain snow pack is our frozen reservoir of water that people and wildlife depend on come the spring and summer melt. A healthy mountain snow pack is especially critical for our agricultural industry across the Willamette Basin. Healthy snow pack is determined by the amount of water stored in the snow pack and not necessarily the measured snow depth. Snow hydrologists keep track of a variable, called the snow-water equivalent (SWE), at 82 SNOTEL sites in Oregon, to make stream flow forecasts come spring.
Snow data at the Mt. Hood SNOTEL site from 2017-18 describes what a below-normal snow pack looks like. See graph below. The snow pack depth over last winter settled quickly throughout storms, as seen by the sharp increase and decreases in the black line. However, the SWE, blue line, continued to increase all winter long. This is the signature of warm storms dropping heavy and wet snow on the mountain. Something that hydrologists like to see. Storms in mid-February through mid-April brought even more heavily saturated snow to the area, providing much needed moisture. The Mt. Hood test site saw better winter conditions compared to many other SNOTEL sites in Oregon last winter.
This’s years NOAA Winter Outlook is predicting a weak El Nino to form, which suggests warmer than normal temperatures this winter season across the Pacific Northwest. Drought conditions throughout Oregon will likely continue as we head into the cold months. And the variability of how much snow will fall in the Oregon Cascades still remains high. Our best case scenario would be for warmer storms to bring saturating snowfall into the high terrain as the winter season unfolds. You can track our SWE % of Normal throughout winter by clicking here.
Oct. 30, 2018 Snow Water Equivalent % of Normal in Oregon.