Update: Friday Night / Saturday Morning Snow
Update: Friday Night / Saturday Morning Snow
8:45am Friday —
Good morning! Well, it looks like my forecast thoughts over the past few days were pretty close. I am getting reports of sticking snow overnight last night down to as low as 850ft near Amboy, WA. last night. There was also a good 1-2″ blanket of white along the northern Washington coast at Forks last night. Around Portland / Vancouver I am getting reports of snow falling in the 8am hour down to as low as about 750-950ft with a mix of rain and snow down to about 500ft. The coast range of northern Oregon saw plenty of snow last night as well. I see snow on the ODOT cams at both Lees Camp (600ft) and Hwy 26 sunset summit (1,600 ft). ZigZag, Oregon also saw snow on the ground last night at the 1,300ft level of Hwy 26 heading to Mount Hood.
The center of a cold upper level trough of low pressure will be right over us today and tonight. As the day progresses, showers will build across the area. Anyone above the 1,000ft level will likely see some sticking snow this morning, but it will melt. The rest of us may see a flake or two below that elevation. Now, what about late tonight? That is looking very interesting. A small disturbance will rotate down over the area later this evening and it is well advertised on this mornings 12z WRF and NAM. It looks like it will drift right over Portland and Vancouver anytime between 11pm and 4am tonight. I personally feel that models are running a bit warm today, as we are seeing snow below where models indicated at this time last night. If that trend continues, then I would expect to see sticking snow to 500-750ft tonight and flakes down to the valley floor after 12 midnight. Amounts will be light, but the WRF and NAM insist on a more organized batch of precip hitting from Salem to Longview about 2am Saturday morning. These will likely fall as snow to almost all elevations with the sticking stuff staying above 500-750ft at this point.
Stay tuned here for further updates throughout the day and this evening. The next batch of detailed (mesoscale) models will be out about 8pm and I plan another update at that time.
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Steve Pierce
Update: Friday Morning Snow?
4:45pm Thursday —
I just got a good look at the afternoon run of weather models and they look about the same as they have for the past few days. What has changed a bit is the elevation that snow “could” fall down to overnight tonight, tomorrow and into Saturday morning. No longer are models showing “sticking” valley snowfall, but more likely a snow/rain mix and that would mostly be concentrated in the overnight hours. Trout Lake had a good dumping over snow last night per my “always ready weather commando” friend, Dick Knight. The snow level will continue to drop tonight as a broad area of low pressure swings into the Pacific Northwest behind yesterday’s front. At this point I see snow falling down to about 1,000ft, which eliminates about 90% of the folks in the metro area. Friday and Saturday will likely be the coldest two days so far this fall season, with high temperatures barely making it to 40 both days. It will feel very raw outside through the weekend. I will update everyone here as conditions warrant, so make sure and check back. I suspect some residents in the higher elevations (above 1,000ft) around the metro area will see some snow between today and Saturday, but nothing on the valley floor. Stay tuned for more updates as needed.
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Steve Pierce
Friday Morning Snow?
Tuesday 11:15am
What’s the best part about Friday? Everything, right? How about a Friday with a little snow before the holiday next week? Do you like Friday even more now? Well, depending on which weather model you look at, it could be wet or it could be a little white around parts of the Portland / Vancouver metro area this weekend, especially in the hills. The freshly minted 12z Euro model output continues to insist that a surface low will spin up just off the coast and slide just south of Portland on Friday morning, tossing light precipitation over the top of a cold air mass that will be in place in wake of the front that passes by Thursday. The Euro has a very good track record.
Here is the snowfall forecast – Click here
Here is the surface map forecast – Click here
As I mentioned above, it clearly shows the surface low coming ashore about Tillamook and drifting over or just south of Portland. The other link shows very light snow over the northern end of the valley from Oregon City northward through Clark County with nearly calm winds from the surface through 850mb (5,000ft). Will this transpire exactly as shown here? Not likely. But it is important to note that the Euro has shown this in one form or another for the past few days. There is something to be said for model “trends.” The other big model is the GFS and it shows a similar set up, but the low pressure system coming in near Tillamook is noticeably absent. Which model will win out? Snow or no snow? My suggestion — “stay tuned” right here and I will keep the blog updated. If I were issuing a forecast right now (12 noon Tuesday) I would say, “there is the potential for a little light snow or rain/snow mix below 1,000ft Friday morning” and leave it at that for now. These are such small (mesoscale) features that a little shift in the model data can make a huge difference. More details to come, so check back often in the coming 2 days and I will post updates as needed.
No matter what happens, this is looking like a very light dusting and nothing more. The biggest factor will be available precipitation at the time we are the coldest. Models are simply not giving us much to work with. If we do see a little snow this weekend you will need to head to higher elevations to see anything decent. My favorite spot is up on Livingston Mountain just east of Vancouver. It is only a 15 minute drive east from the Portland metro area. You can’t beat that for quickly getting to 1,900ft of elevation. If I had the proper vehicle I could make it to Larch Mountain (10 more minutes east) and end up at 3,000+ feet of elevation. But considering the one lane dirt road drops off 500ft down the mountain side, I think I will pass on that one for now.
Don’t forget — get my latest weather updates now via Facebook. Send me a friend request and I will add you in. See: http://www.facebook.com/stevepiercevancouver
Stay tuned!
Steve Pierce
President – Oregon Chapter of the American Meteorological Society
stevejpierce@comcast.net
http://www.piercevideo.com/weather.shtml
http://www.ametsoc.org/chapters/oregon/