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La Nina Slams Pacific Northwest

After a six week break, La Nina is back with a vengeance across the Pacific Northwest and she is bringing plenty of fury with her! Several cities and counties in both Washington and Oregon have declared states of emergency. In just the past four days alone, Oregon and Washington have been pounded with record setting snowfalls of 15-20 inches in valley locations, an ice-storm with power outages affecting more than 100,000 customers at a time, mudslides, 110mph coastal winds and now record setting rainfall and flooding. Oregon and Washington are currently split in half by an arctic frontal boundary. Most of Washington state remains below freezing with many locations reporting freezing rain or snow for the past several days. Oregon also received a large dump of snow earlier this week, but is now on the south (warmer) side of the frontal boundary. Temperatures rose from near freezing to above 50 degrees in a very short period of time over western Oregon this week. At the same time, a steady stream of precipitation known as a pineapple express reached deep into the tropical Pacific and is aiming directly at Oregon. Rapid rises in freezing levels over Oregon have lead to very fast snow melt. Combine that 5-10″ of rainfall in just 72 hours and you have the perfect set up for flooding. This is a classic La Nina signal. Seems like the only thing we are missing this winter is a region wide windstorm, which the area is overdue for.

A similar set up to this week’s event occurred in the first week of February 1996 and lead to the largest flood in many locations around Oregon and Washington since December 1964. This time it is occurring on a smaller scale all around, including less snowfall, rainfall and cooler temperatures. However, the same ingredients are at play. In Oregon’s Willamette Valley from Salem south to Corvallis, residents are seeking higher ground as flood waters rose rapidly on Thursday. The Cascade mountains are also getting hit hard. After picking up plenty of fresh snow, many resorts are now facing increased avalanche hazard. Winds gusted to 119mph on Mt Hood, just above Timberline Lodge at the 7,000ft level this week. Seattle is still waiting to thaw out from the deep freeze and ongoing ice storm. Anything is possible in a La Nina winter and is usually marked by swings from one extreme (cold) to another extreme (pineapple express / warm) in a very short period of time. This meteorological phenomenon occurs when both the sub-tropical and polar jet streams collide over the Pacific Northwest at the same time, just as they did in February 1996.

In October, meteorologists at the 19th annual Oregon AMS Winter Weather Forecast Conference in Portland warned residents that the majority of winter’s wrath would likely arrive in January and February. Those forecasts are available for review on the Oregon Chapter of the American Meteorological Society’s web site under the “meetings” page at: http://www.ametsoc.org/chapters/oregon/. I am impressed with the skill of our forecasters at this year’s conference. They issued detailed forecasts months in advance. So far they have hit the nail on the head with the active January pattern we are now experiencing. Hats off to them. If their forecasts continue to verify, we should expect to see a lot more active and potentially record setting weather to come this winter.

The Pacific Northwest is in the beginning stages of what is known as the cold phase of the PDO (Pacific Decadal Oscillation) which is marked by 25-30 year spans of cooler and wetter than normal weather in Pacific Northwest. The last warm phase of the PDO lasted from about 1976-2007. The switch to the cold phase of the PDO started off with a bang when record setting Christmas snow fell across the Pacific Northwest in December 2008. In the winter of 2008/09, Portland received the most seasonal snowfall (24″) since 1968/69 (34″). Since the change to the cold phase of the PDO, Portland has since experienced snow and/or arctic air every winter. That’s four winters in a row (2008-2012) and is the first such feat since the winters of 1953-1957, which occurred during the last cold phase of the PDO from 1948-1975. If this week’s weather isn’t enough for most folks, longer range computer models suggest the Pacific Northwest could be in for a “rinse and repeat” near the end of the month. After all, it’s a la nina winter and nothing would surprise me.

Stay Tuned!
Steve Pierce

Don’t forget — you can now get my latest weather and climate updates via Facebook. Send me a friend request at http://www.facebook.com/stevepiercevancouver and I will add you in. Not on Facebook? E-mail me at stevejpierce@comcast.net. Don’t forget to bookmark this blog at http://www.columbian.com/weblogs/weather for my latest thoughts. Are you a professional meteorologist or just interested in weather? Why not join the single largest chapter of the American Meteorological Society (AMS) in the country with nearly 200 fellow members? The Oregon chapter of the AMS is just $7 a year. We host eight monthly meetings from Sept-June, including the annual Winter Weather Forecast Conference in Portland each fall! Even if you are not a local resident you can still stay updated via e-mail on all of the latest chapter happenings, upcoming meetings and historical weather stats. For additional membership details or to download a membership application please see http://www.ametsoc.org/chapters/oregon/membership.html

Steve Pierce

Steve Pierce

Steve Pierce is widely known as Oregon and Washington's "go-to-guy" when it comes to fast, accurate historical meteorological research and forecasts. Steve is currently the President of the Oregon Chapter of the American Meteorological Society (AMS). Steve is also recognized as a regional weather commentator and blogger who can be heard on local radio stations and seen in print media outlets across the Pacific Northwest. His Weather Blog is hosted by the Columbian Newspaper in Vancouver. Check it out! He is a third generation resident of Vancouver, Washington and holds a degree in Communications. Both sets of Steve's grandparents migrated to Vancouver during World War II. One set traveled from Lenox, Iowa to work in the Kaiser Shipyards supporting the war effort. The other set came to Vancouver from Olympia, Washington to work as educators for the rapidly expanding Vancouver School District. When the war was over, both sets of grandparents decided to stay in Vancouver and continue raising their families, as did thousands of other families at the time. Those who are most familiar with Steve can attest to the fact that weather is his true passion. His love for "all things weather" began at the age of 7 when Mt. St. Helens erupted in 1980. He was fascinated with which direction the ash plumes were headed. Then came the very powerful windstorm of Friday, November 13, 1981, also referred to as the "Friday the 13th" storm. This was the strongest storm to hit the Portland / Vancouver area since the great Columbus Day Storm of 1962! At age 11, he was asked to publish an extended weather forecast for his elementary school's weekly newsletter. In the 1980's, at age 14, Steve was the youngest of KGW-TV's local "weather watchers" and would phone in his daily Vancouver weather stats to then television meteorologist Jim Little for use on-air. Steve has lived through all of the major Pacific Northwest weather events of the past 30 years, and then some. The most notable events include; the bitterly cold winter of 1978-1979, the record setting snow storms of January 1980, the summer heat wave of August 1981, the windstorms of November 1981 and December 1995, the severe arctic blast of February 1989, the record flood of February 1996, the historic ice storm of January 2004, the Vancouver tornado of January 2008 and the record setting snow storm of Christmas 2008. Not to mention every Mt. St. Helens volcanic eruption in between. With access to the most extensive set of historical weather records available to date, Steve has personally designed and integrated a proprietary system that gives him the ability to quickly locate and manipulate weather data as far back as the 1800's. As one local Meteorologist put it, "Steve has fast access to historical weather data that is needed for media, agriculture, business, personal, historical and other climatological needs. He can quickly manipulate the data in many different ways. His forecasts are also quite accurate, especially at longer lead times." Steve also provides local storm assessments, narratives and weather presentations to the general public, as requested. In his spare time, Steve enjoys spending time with his family, the outdoors, vacationing at his family's coastal cabin and just relaxing! By the way, do you like your weather on the "extreme" side? So does Steve! Whether it is collecting damage assessment data & photos after record setting 125 mph winds at the coast in December 2007, being one of the first on the scene after the January 2008 Vancouver tornado, or feeling (literally) the awesome power of 100 mph wind gusts at Oregon's Crown Point in January 2010, Steve has experienced it all! As Steve says, "don't just love weather, live weather!" Check out Steve's personal weather website at: http://www.piercevideo.com/weather.shtml