La Nina means cool, wet conditions to stay

December 31, 2017

Re-published with permission from the Columbia Basin Bulletin Colder and wetter-than-average conditions persisted across the Pacific Northwest in November, with a La Nina weather pattern becoming well established and strengthening during the month, and the outlook is for much of the same going into March. Those conditions starkly contrast with November weather and the outlook for much of the rest of the contiguous United States, particularly the Southwest, where Arizona and New Mexico had record-warm Novembers. From January through November nationwide, it was the third warmest on record, including the seventh warmest month of November on record. But again, the Pacific Northwest stood out from most of the rest of the country with near-average temperatures from January through November. Those conditions persisted during the month of November in the Northwest, along with above-average precipitation. Notably, the Pacific Northwest lies outside of any drought designation, with the exception of a portion of Northwest Montana. But 26 percent of the country is considered to be in drought by the U.S. Drought Monitor. The powerful La Nina influence, driven by cooler-than-average sea surface temperatures across the equatorial and eastern Pacific, has taken hold with forecasters having higher confidence in their three-month outlook models. “We are forecasting La Nina conditions to persist through the winter,” said Brad Pugh, a NOAA Climate Prediction Center meteorologist, during a Thursday teleconference. That is expected to translate to higher-than-average temperatures and drier conditions from the Southwest into Texas over the next three months. Conversely, Pugh added, below-normal temperatures and above-average precipitation are favored across the Pacific Northwest and into the Great Lake region through March. Notably, the highest confidence for wetter-than-average conditions for the next three months is in the Northern Rockies of Idaho and western Montana. The U.S. Seasonal Drought Outlook predicts the entire Pacific Northwest, including western Montana, will be void of drought conditions over the next three months.