The main weather story continues to be the possibility of lower elevation snow at times Saturday through Tuesday. This is another one of those situations where we don’t have a cold east wind blowing out of the Gorge or a cold air mass to give us a widespread snowstorm. Instead we just get showers and clearing periods Saturday and Sunday and it happens to be a colder version of the “showers and sunbreaks” pattern.
In general, the higher up you live the better chance you have for sticking snow. All areas dry out Sunday evening and that’ll be the end of it until Tuesday.
First the outlook for regular folks, then the in depth model & data discussions for my “weather friends” down below.
IN THE LOWEST ELEVATIONS ALONG I-5 HERE IN THE VALLEY: This includes Salem, Portland Metro Area, Vancouver, St. Helens, & Longview. Mainly rain showers during the day Saturday, then mixed rain/snow showers Saturday night through Sunday afternoon. If we get a dusting of snow, it would likely be early Sunday morning, but only some random neighborhoods will get that dusting. Most of us in the lowest elevations will get nothing better than snowflakes in the air this weekend.
NEAR AND ABOVE 1,000′: This includes the West Hills, Mt. Scott, Sandy, West Salem Hills, etc. This also applies to areas from 500′ on up in the Coast Range like Vernonia, Elsie, & Timber. Snow showers Saturday morning through Sunday afternoon could give light accumulations, especially during the cooler nighttime hours…1-3″ possible in these areas.
NEAR AND ABOVE 1,500′: This includes Coast Range summits, Hoodland area, Silver Falls, Detroit Lake...Snow showers late tonight through Sunday afternoon; 5-8″ is possible during this time, heaviest up against the Cascades. Snow could accumulate at any time on roads, but snowiest during nighttime/morning hours.
CASCADES ABOVE 2,000′: 18-24″ by Sunday morning, maybe another 6″ during the day Sunday too.
TECHNICAL DETAILS:
Starting tonight, we’re going to see snow levels below 2,000′ for the next 5 Days.
Nice strong cold front just about to the Coast right at 5pm. What a brief taste of spring this morning with bright sunshine and temps quickly zooming up into the low to mid 50s across the metro area before the clouds moved in. East of the Cascades, lots of 60s with southerly wind surfacing all over the place. But forget about spring and check out the cold cumulus behind the cold front. Just 12 hours it didn’t look so great, but now you see the northwesterly flow setting up behind the front with the usual showers streaming towards us.
Models show the deep surface low near Vancouver Island moving by to our north over the next 12-24 hours; WRF-GFS gives us 13+ millibars EUG-OLM gradient by midnight or so, which could give us 40 mph wind gusts. It’s going to be a showery & windy night!
A steady stream of showers tomorrow, with 850mb temps between -6 and -7 degrees means snow sticks even during the day up around 1,500′, but the strong onshore flow and sunshine in between showers means no “stickage” down here in the lowlands.
Cooler air, by just a couple of degrees, for Saturday night and Sunday means a better chance for sticking snow slightly lower, but moisture seems to run out after midday Sunday. So that’s why I think the best window for a dusting down in the lower elevations is later Saturday night through 10am Sunday. Still, I’m not real impressed by what I am seeing. To me this appears to be a slightly lower chance for sticking snow here in the city than what we saw that weekend in January; we didn’t officially have snow during that episode in Portland. I’m not referring to the following Tuesday night when we had several inches. Our RPM looked better at that time than what it shows now: just a sprinkling of snow in some spots in the valleys:
Here is the 12z 1.3km WRF-GFS snowfall graphic…that’s some geographic detail at that resolution!
There is one possible wrinkle, models have been slightly stronger with a disturbance coming down the coastline around midday Sunday that could enhance the showers. Hopefully if that occurs it WILL be midday and not give us anything significant.
Sunday night and Monday we dry out, so Monday should be a real nice, but chilly day with 850mb temps remaining in the -6 to -8 range…brrr! Even so, late February sunshine should get us close to 45.
Tuesday is a challenge as a cold front moves through the Pacific Northwest.
1. We start with a chilly air mass
2. Precipitation rushes in during the morning hours
3. Little to no southerly gradient until midday, in fact light easterly flow early in the day.
4. 850mb temps TOP OUT at about -3, with -6 degree temps ahead of and behind the front.
This could be a good snow producer at/above 1,500′ with snow in the air everywhere to start; at least it’s something to keep an eye on.
After leftover showers Wednesday (similar to Saturday’s weather), we finally see some warmer weather showing up on both the GFS and ECMWF. Not WARM, in fact barely mild, but at least near normal March weather; we could see a bunch of 50s instead of low-mid 40s possibly? How exciting!
Here are the 12z GFS and ECMWF 850mb charts showing the possibility of milder weather:
Chief Meteorologist Mark Nelsen
This from Govt Camp
New Snow: 6 in.
Roadside Snow: 37 in.
Comments: Very high gusting winds and low visibility conditions throughout area. Use extreme caution throughout area.
Last Updated: 02/25/2012 10:02 am
2 in. snow o/night
3 inches of snow up on skyline right now.
hey i live out east of Tacoma,WA and the Olympic rain shadow is going does anyone know if it will change directions to let moisture in later
Well Mark was right. Under a heavy shower it sticks and turns everything white, then as soon as it slows down, it melts off. It’s coming down pretty heavy right now.
That’s what I have here at 1,000′ east of Corbett. Looks like about 1″ earlier this morning, now just wet road and slow melting even though it’s still snowing.
There’s been a dusting of wet snow in Seattle’s north end this morning, but nada here in West Seattle so far. Conditions are definitely marginal: 38 degrees here at 400 feet elevation; evaporation would probably get that down to 34 or 35 in a heavier shower. Radar shows the line of showers slowly working its way south, so we’ll see if anything happens here before it dissipates.
Forecast to be a better chance for snow after midnight tonight. With the temperatures so marginal even before the daytime warming gets going, any showers that form here this afternoon probably will be cold rain.
Here we go!
http://inws.wrh.noaa.gov/weather/alertinfo/5027972
Just had a shower roll through here with about a 50/50 mix. 37 degrees.
SE portland big snowflakes 37 degrees now:)
Up here at my moms in yacolt wa 1300ft there is about 1\4in snow stopped now
PDX is reporting rain/snow now, warming slightly here. Sitting at 33 currently with light-moderate snow.
Snowing in Eugene. Had some really big flakes, light dusting on the grass and cars. Nice suprise.
Heaviest snow of the morning yet, about 3/4 inches on the ground and 32.
We are at about 550′ and it has been snowing steadily since about 6 am…a few 5 minute breaks. It is sticking to everything. Trees, grass, road, cars….
snowing hard in Sandy, maybe an inch so far
Snowing and sticking to grass and bark here. 34 degrees.
Just saw Brian live on the air say near 1,000 feet near nothing today….Its dumping here and 31 now at about 800 feet above sylvan, getting close to half an inch and piling up fast.
Roads are white as well.
I said light accumulations this morning, but obviously some areas have had more than that (like Sandy). Tonight and tomorrow morning looks to be a little more interesting. Has it all melted up there yet?
Everything is melted now.
1″ here – started about 6:15,
32 even and still coming down.
Beautiful!
Sticking line looks like 600′ in Happy Valley. No snow on my roof but the roofs up the hill at 600′ are white. Mt. Scott looks snow covered.
Moderate snow and 32 here!
Little over 1/4 inch here
Huge flakes coming down here now.
Cloudy and 30.7 at the moment. I have not measured, but it looks like I’ve picked up about 1/2″ of snow.
34.5 and snowing heavily in Boring. Sticking to everything but the road. I was not expecting this until tonight…but I will take it!
We now have about 1/2″ and still coming down hard. Sticking to the road now. 34.2
Light snow in Happy Valley 500′ but not close to sticking. 33.6 deg.
Coming down harder now but still not sticking.
Snowing over Sylvan above 600 feet at 6:00 am. Not sticking to surfaces… Yet.
2/24/2012 Oregon (All) Temperature Summary
Warmest:
High:70 at CW2426 Warmsprin(1572 ft)
Low: 45 at Lexington Airpor(1624 ft)
Coldest:
High:32 at HARL BUTTE(6071 ft)
Low: 8 at CRANE PRAIRIE (5500 ft )
Largest Diurnal Change: 49 degrees
Valley Falls (US (62/13 ) (4324 ft )
Heaviest Rainfall:
1.13″ at DW0237 Lees Camp(699ft)
Was 63.5F on my continually fan aspirated thermometer this afternoon here in SE Eugene…now 39.5F and raining…at 514′
Is it just me, or do some other people here find it annoying that some weather modeling maps are in Metric units while others are in Imperial? Perhaps I just have Mars Climate Orbiter paranoia, and that we might screw things up by getting the two mixed up!
Looks to me like the shower activity off the Oregon coast is merging together as one large band. Down to 40 here now.
Looks similar to a bent-back occlusion as it swings around the low to the north…nice
Bent back occlusion. Wasn’t that the name of a movie a few years ago?
No, that was an old rock n’ roll group. I believe they were a Frontal Band for the Rolling Stones.
Temp steadily dropping. Currently 36.6.
All I want is an inch at 250 feet in Beaverton. 50% chance, mark?
An inch? I give it 30% chance at 250′. Westside metro looks driest to me…rain shadowing off the Coast Range.
On tuesday next week, you have 30 for the low and 43 for the high. I hope that 43 switches to a 34 and we get a snowstorm. But 99.99% that will happen.
Down to 42 here with on and off rain showers.
Wow! Just heard some rumbling noises from inside the house… I walked out to the front, and I must have been in some 50+ gusts if I had a hard time standing still the whole time.
http://mesowest.utah…n=KLMT&time=GMT
Just 45 minutes ago there was a 44mph gust reported at KLMT station. Now its even higher than that. But I need to wait another 13 minutes for the update. Finally, some WIND!
http://mesowest.utah.edu/cgi-bin/droman/meso_base.cgi?stn=KLMT&time=GMT
Last time it snowed it was weird because i live at 397′ and i had wet snow (downtown was plain rain) and when i went to powell butte nature park witch is 630′ it was a ”blizzard” with accumulating snow compared to my house and its only a 300′ difference! thats why we ”portlanders” need to forecast in 200′ ”increments”!
The problem with that is five miles from that spot maybe it was light precipitation with nothing sticking at 800 or 1000′. So what was the snow level in that case?
I’m not trying to sound like a jerk, but snow level is based not just on temperature, but precipitation coverage/intensity. Once in awhile, if we have steady precipitation across a wide area, then it makes more sense to forecast snow level in less than 1000′ increments, but otherwise it’s just a guess that makes people think we can forecast snow level more accurately than we can.
That makes sence:) thnx!
There’s got to be a way of expressing those smaller increments in a manner that takes into stride all the uncertainties that Mark rightfully brings up with respect to snow level precision. I think what I’m getting at here are probabilities, and how we could plot out an elevation-probability chart that is more precise than 1000-foot increments because, well, probability takes care of uncertainty!
That is a good point Mark. On February 14th at the high point on highway 214 between Sublimity and Silver Falls (1750′) there was no sticking snow, but by the time I got to the bottom of the hill near South Falls (1300′) there was about 1″ of snow on the ground. More than likely a heavy shower came through a couple miles north at South Falls thus they had accumulating snow almost 500′ lower than just a couple of miles away. Just a recent example to illustrate your point.
That’s a perfect example Andrew.
The house at 1750′ was mad because the weather guy said it would stick down to 1,500′ and he didn’t get any. The guy at South Falls at 1300′ said “yep, they screwed up the forecast again, it snowed lower than 1500′!”. You can’t win unless you get a little more general with amounts.
(DIDNT TRY TO BE RUDE TO ANYONE IN MY COMMENT)Lets wait and see!!!
Ah, boring temps in store after this cold spell (i.e. near seasonal norms). I was hoping we’d get to see the 850mb temps jump by 15-20C in a single week – unseasonable warmth immediately after unseasonable cold, enough so to get some of us complaining about the heat
The inside of my greenhouse was 73 this morning in the sunshine while it was 46 outside…very cool! If felt humid and smelled “earthy” in there as well which was really nice. My spinach is starting to come up.
Sounds like Sunday is one of those days to head up for some skiing. The low elevation snow will keep away the crowds and the conditions will be fabulous.
Shhhhh… I’ll be up at Meadows with my kids.
Don’t know how often this updates???? But shows WA temps
http://www.wsdot.com/traffic/weather/default.aspx
I figure, by Wednesday, we’ll all really know whether or not there was snow this weekend.
One other possibly “wrinkle”: A friend of mine messaged me earlier, said it’s been snowing off and on since about Noon near sea level in Vanc. BC today, pre-FROPA. Your 1.33km WTF-GFS map doesn’t even show that post-FROPA!
Don’t you just love wrinkley forecasts???
*WRF-GFS…
WTF?!? Hahaha!!!
WTF-GFS would be lala land.. Whenever it spouts nonesense, call it that!
Nice Erik
Erik,
Don’t drink and post comments please…
It didn’t stick much or at all did it? Looks like Vancouver Airport had snow & rain and 36 midday. I think the WRF-GFS did fine. It shows temps around 40 midday today.
Ouch! Hey, FWIW I haven’t been drinking…
At any rate, I wasn’t in Surrey, BC today, so I can’t vouch for their snow, sticking or otherwise. Point being, it snowed, and with that airmass moving toward us, snow, sleet and an unexpectedly low midday maximum of only 36 might be in our future? We won’t know until it’s all said and done.
Blame stupid autocorrect for my previous misspellings, I don’t always go back and check when I’m typing in a hurry… not until after the fact, anyway.
Time for a beer? I guess I’ll put the internets away for the night…
You are right Mark. At least a chapter’s worth of writing. Not quite a book.
How long did that take you to put down?
An hour
For what it’s worth Mark, you’re a wonderful writer. As a freshly graduated college student, I definitely found inspiration in your writing style and often find myself mimicking your techniques. Thanks again for your dedication to help solving the unknown!
Thanks for the compliment Brandan. You mean “snarky, yet thoughtful”???
I try to write like I speak, except with writing I don’t have to worry about blurting out anything stupid or inappropriate.
Lets hope for some 60 days in mid-March.. I am so ready for that.
Umm… Brian? There are only 31 days in all of March, dude! o_O
Why not hope for 61 days of March instead of just 60? EH?!?
YAY!!! o_O
Aww, are we really “weather friends”, Mark???