Predicted El Nino does its thing

The National Weather Service has warned for months that this year’s El Niño weather pattern will be among the strongest on record, with predictions for higher-than-normal precipitation and warmer-than-normal temperatures in the Pacific Northwest that have proven to be true.

The latest El Niño update, issued on Dec. 10, predicts the pattern will continue.

The forecasts for the El Niño Southern Oscillation — a pattern of warm-water conditions in the equatorial Pacific Ocean — have taken shape in the form of a deluge of heavy snow and rain in the Pacific Northwest this winter,

“Most models indicate that a strong El Niño will continue through the Northern Hemisphere winter 2015-16, followed by weakening…” the latest advisory states. “The forecaster consensus remains nearly unchanged from last month, with the expectation that this El Niño will rank among the three strongest episodes” recorded. This year’s El Niño pattern rivals the 1997 pattern, the strongest on record.

“El Niño is expected to remain strong through the Northern Hemisphere winter 2015-16,” with a transition to “neutral” conditions expected by late spring or early summer of 2016, an advisory posted on December 10 states.

“El Niño has already produced significant global impacts and is expected to affect temperature and precipitation patterns across the United States during the upcoming months … Seasonal outlooks indicate an increased likelihood of above-median precipitation across the southern tier of the United States. Above-average temperatures are favored in the West and northern half of the country with below-average favored in the southern Plains and along the Gulf Coast.”

NASA has been tracking the recent stream of moisture into the Pacific Northwest of the U.S., calling it a “Pineapple Express” that has resulted in “the continued ‘training’ of rainfall in the Portland, Ore., area with at least one death reported. Western Washington is also on flood alert due to the deluge.”

Above-average precipitation has extended into western Montana, where flood watches and warnings have been issued, particularly around Libby.

“Riding a pumped up jet stream, a convoy of west storms have pummeled and drenched the Pacific Northwest for the past week,” said Bill Patzert, climatologist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “Following a couple of years of regional drought, all this snow and rain has whiplashed many Washington and Oregon communities from extremely dry conditions into flooding and even landslides. Once again, the old adage, ‘Great droughts end in great floods’ comes to mind.”

Patzert said that this hose of heavy moisture is originating in the far Western Pacific Ocean. Sweeping out of the tropics, meteorologists refer to these relatively narrow, moisture laden rain and snow producers as atmospheric rivers. For the U.S. West coast states, these storms supply up to 50 percent of their water supply.

"They can be ‘fast and furious' and damaging, but play a large role in sustaining our water supplies in the normally dry West," said Patzert.

Rainfall that occurred from Dec. 2 to Dec. 9 was measured from NASA satellites, finding that many areas from northern California into Washington received rainfall totals greater than 6.3 inches compared to historic averages for the same period.

Oregon Gov. Kate Brown December 10 declared a state of emergency to exist in Benton, Clackamas, Clatsop, Columbia, Lane, Lincoln, Linn, Marion, Multnomah, Polk, Tillamook, Washington, and Yamhill counties due to a severe winter storm, including high winds, flooding, and landslides.

"Heavy rains and wind have required the evacuation of residences, and mudslides and high water have severely damaged or blocked major roadways in these areas of the state,” Brown said. "The emergency declaration ensures state resources, emergency response personnel, and equipment can be activated to respond to communities in need if their local resources are exhausted."

The state of emergency is in effect until further notice.

Washington Gov. Jay Inslee on Dec. 9 proclaimed a state of emergency in Washington following days of hazardous weather with landslides closing major highways, high winds knocking out power to thousands, and rainfall causing wide-spread flooding of roadways, homes and property.

The proclamation covers a series of storms that started on Nov. 30 and is continuing. The storms produced high winds and heavy rainfall that saturated soils, caused major flooding, landslides, stream bank and slope erosion, fallen tree limbs, broken and uprooted trees, and flying debris.

Some of the most severe flooding has taken place in Cowlitz, Lewis and Snohomish counties, but there also were wind and flood advisories in eastern Washington.

Cowlitz County and each of its cities have declared an emergency, with other counties assessing their damages and needs.

“There are people in need across southwest Washington and the rest of the state and we’re here to provide whatever assistance the local communities require,” Inslee said. “We’re in this together.”

The National Weather Service’s Weather Prediction Center, as of Dec. 11, said rain and snow will continue across parts of the Northwest with scattered areas of flood watches, warnings and advisories across western Washington, western Oregon and northwest California.

Some selected storm total rainfall from Monday, Dec. 7, 4 p.m. to Friday, Dec. 11, 6 a.m.:

--Washington: Stevens Pass, 5. 7 inches; Seattle, 3.55 inches; Olympia, 4 inches.

--Oregon: Nehalem, 7 inches; Portland, 3.2 inches.

--Idaho: Schweitzer Basin, 5.2 inches; Lolo Pass, 1.7 inches.

--Montana: Flattop Mountain, 4.2 inches.

Some selected storm total snowfall for the same period:

--Idaho’s Ketchum had 15 inches; Montana’s Island Park 19.8 inches, and Washington’s Stevens Pass 4.5 inches.