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ANOTHER SNOW EVENT TUESDAY?

Many residents from Salem, Oregon north to Vancouver, Washington woke up to snow in the air Saturday morning and continuing throughout the day Saturday. My thoughts from earlier in the week pretty much played out as forecast. Actually, the snow fell a bit lower than I was thinking, with snow sticking down to about 900ft and nearly all locations seeing snow in the air down to sea level. Now my eyes are turning to what looks to be a very interesting set up for this coming Tuesday into Wednesday. It is getting late in the winter season so these forecasts are a little harder to pin down. So, here goes.

System #1 is passing by right now and will exit the area on Sunday. In its wake is an area of drier and colder air will slide down over the Pac NW Sunday night. You can see thicknesses drop to about 520dm at 1000-500mb Sunday afternoon through Monday morning in this image below:

Overnight lows on Monday morning will be below freezing in most areas west of the Cascades, outside of the coast line. Then on Tuesday, another very cold system comes down the BC coast right over the Pac NW. This system appears to be as cold or even colder than the one that just went through the region this weekend. Here is the 925mb temperature forecast from the U of W WRF for Tuesday morning. This is cold enough for snow in the northern end of the valley from Portland north into SW Washington and on north towards Seattle:

Then the center of the upper level (500mb) trough moves right over Portland on Wednesday morning along with a surface low in nearly the same position as the upper level trough:

By 7am Wednesday, 925mb temperatures have warmed a bit, but are still cold enough to support snow to some very low elevations:

Here is the WRF sounding forecast for Tuesday morning as the overrunning precipitation begins. That my friends is VERY close to sea level snow. This image looks even better for PDX snow than today’s snow event did :

Finally, the WRF snowcast shows more snow in the 24 hours surrounding Tuesday and Wednesday than it did for this weekend. Again, areas from Portland north could be under the gun for snow:

So, to sum it all up —

500mb trough of 522dm directly over Portland Tuesday morning.
Overrunning precip coming in at the coldest time of the day.
1000-500mb thicknesses remain about 525dm through Wednesday.
925mb temps below -4C as precip begins.

Those are good ingredients for a little snow in Portland and points north on Tuesday. The track of the surface low will play a MAJOR role in what if any snow Portland gets Tuesday. If the low stays to the north, it will be a brief shot of snow followed by a warm up. If the low stays just south and remains weak (as models have trended) Portland could be in for more snow than even currently modeled. Caution — this is just one model run, but I have noticed a distinct trend colder with the Tuesday system over the past 36-48 hours on the models. This will need to be watched closely over the next 24-48 hours to see what the models have in store for future runs. I will update here as needed.

Finally, don’t forget about the great weather meeting we have planned next Tuesday in Portland. The topic is “Summertime Lightning Forecasting” and is hosted by KPTV and the Oregon Chapter of the American Meteorological Society (AMS). Our guest speaker will be Meteorologist John Saltenberger. This is going to be a really informational meeting. You can see all of the details at: http://www.ametsoc.org/chapters/oregon. Hope to see some of you there!

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