Well tomorrow is the “big day” for us weather weenies. I just finished perusing the 00z model runs…here are my thoughts:
1. South wind kept us from getting a 1-2″ surprise in the Metro area today. Models handled our little snow burst well, except the timing was off…it showed up 2-3 hours early. That light onshore flow was expected. Now it’s disappearing as a 2nd low is spinning down the coastline. It’s near Astoria right now; models show it spinning overhead and into eastern Oregon by morning.
2. Behind that low, a colder atmosphere is pulled down from the north overnight. That plus some clearing should make for an icy, but dry start Monday.
3. Between daybreak and around 4pm tomorrow, a stationary front (the leading edge of the arctic air) sits between Astoria-Portland-Condon. A 3rd surface low develops along the front and moves right overhead midday or afternoon. I’m depending on that to give us a possible 1-2″ of snowfall…a bit more moisture than models show (but that happened today too). We start cool again in the morning tomorrow, plus our model (RPM) and WRF-GFS show the boundary right over us, instead of up north of Kelso. That should mean no south wind and we shouldn’t have a problem getting snow to stick just about anywhere from Portland north.
4. The arctic front then suddenly makes it’s move behind the low after 4pm, sagging south to Eugene by 10pm tomorrow night. Most likely at least a trace of snow would accompany that front even down into Salem and Eugene. As a result, we should freeze up quickly after dark tomorrow.
5. If you have plans to be out and about after the noon hour tomorrow, make sure you have a plan to get un-stuck if we suddenly get a surprise 2″ dump of snow and traffic grinds to a halt! That seems unlikely, but definitely possible.
Now this is the scenario that I’m basing my forecast on. The NAM moves the low by a bit farther to the north, which puts us into a similar situation that we saw today (minus the eastern Clark County cold spot). If so, we’d only get a trace or so as the arctic front finally slides south.
So here’s my forecast:
1-2″ snow Portland north to Longview midday-evening tomorrow.
Trace from Woodburn south into the Valley.
I lowered Tuesday’s high temp forecast based on at least 1″ of snow cover in the metro area. If we don’t get snow on the ground, I’d guess 33-35 degree highs.
We can talk about that sudden appearance of moisture for Wednesday AFTER we get through tomorrow. Actually, I suppose you can talk about whatever you want on here, but I’m busy focusing on tonight and tomorrow.
It’s still hard to believe it’s such a cold atmosphere plunging into our area tomorrow night. -13 to -15 degrees C. at 850mb? Imagine if it was January…then it would be quite a bit colder at the surface. I’d probably go for highs in the low-mid 20s.
Chief Meteorologist Mark Nelsen
Mark has posted a new blog
True, we are getting south winds in Portland. But don’t south winds normally bring temps at least in the 40′s? The fact that its around 35 deg and not climbing must say something about the colder air being close by and things not being typically normal. Just a thought.
NWS statement this morning does seem to favor a track of the low to the north of PDX but the cold air does eventually make it here and I would think there should still be some moisture around? I would say 10-30…mm a good bet.
Well lookie here
…oh ya baby!!!
Winter Storm Warning
Statement as of 9:37 AM PST on November 22, 2010
… Winter Storm Warning in effect until 10 PM PST this evening
for the Seattle… Tacoma… Everett Metro areas including the Hood
Canal area… the Kitsap peninsula and the eastern Puget Sound
lowlands…
The National Weather Service in Seattle has issued a Winter Storm
Warning for the Seattle… Tacoma… Everett Metro areas including the Hood
Canal area… the Kitsap peninsula and the eastern Puget Sound
lowlands for heavy snow… which is in effect until 10 PM PST this
evening. The Winter Weather Advisory for this area is no longer
in effect.
* Some affected locations… Everett… Gold Bar… Seattle… North
Bend… Bremerton… Shelton… Tacoma… and Enumclaw.
* Timing… bands of snow will increase through the early afternoon
and continue into the evening hours. The snow will end later
this evening from the north… but some drifting of the snow is
likely tonight as northerly winds increase to 20 to 30 mph and
gusts to 40 mph.
* Accumulations… expect 2 to 6 inch amounts. Snowfall
accumulations will be quite variable around the area with
heaviest amounts occurring closer to the Cascade foothills and
in localized bands around the central Puget Sound area.
* Wind… light and variable winds through mid afternoon will
become north and increase to 20 to 30 mph with gusts to 40 mph
this evening. The gusty north winds tonight will cause some
blowing and drifting of the snow. The combination of the strong
wind and temperatures falling into the lower 20s will give wind
chill values of 0 to 10 degrees above zero tonight.
* Impact… gusty winds near 40 mph could result in local power
outages… thus consider alternate… but safe… sources of
heat in case this occurs. Otherwise make sure you have
plenty of extra warm clothing or blankets.
Precautionary/preparedness actions…
A winter storm warnings means severe winter weather is occurring
or imminent. Those planning travel in the warned area should be
prepared for hazardous… winter driving conditions and plan
accordingly.
Congratulations!!! You’re the @?$@^ man!!
Huge silver dollar flakes floating down now above Woodland–My neighbor up the hill at 800 feet has close to 8 inches on the ground as of an hour ago.
Another update from up north.
26.7 degrees and snowing at a pretty decent clip, around 3/4″ or so with more on the radar.
Got some bad news for you guys down south. The radar seems to be filling in towards the north(me) and looks like the low is developing on the tip of BC. Not sure how bad this is going to inhibit the movement of the front but it surely can’t help.
Our temp has dropped from 34.4 to 33.6, doesn’t sound like much but when you’ve been around 34 all night. Few cold pockets left in Clark County.
I notice no pressure rises at Astoria…that is strange with a sudden switch to a west wind and pretty strong.
Strengthening Lee side trough south of the Olympics? I think this is causing a problem for us.
KDLS’ DP has dropped 3F in the last 75 minutes and, as mentioned earlier, has a N wind now.
GFS MOS guidance has 2 inches for HIO, 4 inches for PDX.
Low temp Tues Night…predicted to be 6 in HIO, 13 PDX, 16 EUG by GFS MOS.
By the way EUG and SLE have a predicted snowfall by GFS MOS of….0.00 inches.
I think we will beat that prediction by an inch or two
Anyway, things taking shape. Frontal passage will be later than anyone wants. At least PDX will sniff the arctic air 11 (eleven) hours before EUG.
SW winds (light) at 3mph in OLM
How could PDX get twice the snow of Hillsboro? Especially when this isn’t an East wind event.
HIO is closer to coast range…there won’t be east winds until late…like late tonight.
Chris – my theory is that if cold enough moved in to allow the switchover about the same time for Portland and Hillsboro, the precip would be nearer to running out in Hillsboro (being west) than at PDX. But maybe something else informs those different totals. Just a guess.
*cold enough air, that is…
And I don’t know why I called you Chris, Ben. Coffee please!
Are those 2-4 inches today, Paul? Sorry, maybe a silly question, but is there really gonna be that much precip.?
Check out the obs near Ocean Shores, WA….just to the N, NE winds with temps in the 30s, just to the south, SW and west winds and temps in the 40s. That is a very well defined boundary.
That boundary is going to raise our snow level today to near 1000ft.
Longview (ground level) snow just starting to stick on grass, temp 34F. 3 miles east here at work, 37F and mixed stuff. Looks like a fun afternoon ahead…
Columbia Basin, not Columbia Gorge.
My bad!
NWS says the rain will change over to all snow after 1pm down there in Portland.
Where did they say that?
That’s too early.
Downtown and most of metro area…no. Hills around town…maybe.
Just cold rain here…..36°…temp slowly climbing…Light SSW winds.
Snowing hard again
1 1/4
32.7
latest AFD for portland shot down our snow shot until tonight, with not much moisture left. we need that low to track 75 miles further south.
Arctic air really streaming into the Columbia Basin now. It’s going to be tight, but any low level off shore flow will make the difference this evening.
What do u mean? Rooster Rock is up to 40f. and has west winds blowing !!!
Any off shore flow won’t occur until the front clears and when the front clears the moisture does as well. Ya may get a burst of snow with the front but it’s not looking good for a descent accumulation.
rooster rock is not close to the columbia basin, that is in eastern washington. the dalles just picked up a north wind
Well I read that wrong… my bad!
UGH!!! WEST WINDS ARE PICKING UP NOW IN ASTORIA.Winds have been for most part non exhistant till now. GUSTING NOW TO 29MPH. Temp up last hour 4 degrees and now at 39F. This is not good for us at all.
LOL! Tyler and I on same page…
Not surprised. It will probably switch back with a dropping temp around 2-3pm
YUCK! Strong west wind at Astoria:
http://www.wrh.noaa.gov/mesowest/getobext.php?wfo=pqr&sid=KAST&num=72
…sure is easy to see who looks at the glass half-full, and half-empty around here when any type of weather event is looming…..
Yep, good perspective. People see snow 40 miles north of them and get upset because they want it to snow now! If anything conditions over the past 1-2 days have become more favorable for sticking snow in the Willamette Valley/PDX metro. Yes, we have a south wind, but that is not a surprise ahead of an arctic front, once those winds go calm, know that snow is about to begin.
Agree
We’re about to get colder than we’ve been in November since 1985 and people are b(*&ing about snow?? My Lord! It’s coming people, it’s coming. By the look of these comments you’d think it’s going to warm up to 50 or something. If there’s not snow on the ground at 7:00 tonight, I’ll call bust. Until then, relax. And, if you have kids with school tomorrow, let ‘em stay up late. No way they let busses out on a sheet of ice in the morning. Someone used the term ‘flash freeze’ and that is spot on.
The boundary is hung up in North Cowlitz and Southern Lewis County.
All you have to do is look at the temps up there. Some parts of Longview/Kelso are in the mid 30′s, Castle Rock just north of there is 32 and they’ve been 32 most of the night.
Elevation is key south of the front. Around 500 feet in Southwest Washington and 1,000 feet south of the river
South wind at 16 and increasing in SLE
Bust o rama in progress for pdx south, that cold air is hung up north.
No, the true arctic air is actually making a pretty good push IMO.
Not sure I agree. The temps from Olympia north, have been dropping since 5am. That trend is moving south. So to me, it doesn’t look stalled, just the south wind is making it appear that way.
and you already said that
Currently 37.8° with light rain and a light southwest wind.
All of Portland area will be snow by 12 noon. Anywhere there is precipitation it will be snow. Eazzzy call too!
Portland and east, west, or north of I should say bye 12 noon to possibly as late as 2 pm
At 9am: south wind, temps ranging from 36-38 degrees, dew points close to the same. A LOT has to change in the next three hours for that to happen.
I don’t expect anything to write home about before 4:00, if there’s any moisture left at that point.
I could be calling it a little early but either way it will happen eventually
My guess is arctic fropa SLE 10 Pm EUG 3 am
What time for PDX?
4pm
Do you think we remain rain until then? If so, do you think there will be any moisture left for PDX after 4:00?
yes
Any new thoughts on the availability of moisture once we get cold enough for snow? Right Now my thoughts are 2-3″ PDX metro with locally higher amounts to 5″ at the higher elevations and Clark county. 1-2″ Central Valley (Salem/Albany) with isolated 3″ amounts, and 1-3″ S. Valley.
Andrew, I hope you’re right! Would I be considered in the “higher elevations”?
Yes, I think a location like yours has a chance to switch over a little sooner, plus you are probably at least slightly more favored orographically.
ya i was looking at that loop of the cold air advancing south, from what i saw, looked it it would take about 9 hrs to pass salem, so i just hope there is moisture left over,
Yeah, it’s been mostly snow up here this morning, but not sticking and not very many showers…hopefully that will change. Currently sitting at 34 degrees.
Someone whose opinion I respect on another forum says 0.5-3″ Corvallis – PDX
Anxiously awaiting tonights blog entries when this gets lit up like a Christmas tree. Anybody have good tips for driving on ice(other than dont do it…this is not an option for me) Thanks for any replies.
Slow down way before you need to turn or stop. Let off of the gas vs. hitting the breaks. Better to slow down with your tires rolling vs. them locked up. Avoid overpasses, or make NO turns or lane changes on them.
I would say avoid hills when possible, maintain a steady speed as much as possible. I had to do a lot of driving back in Dec. 08′ and then last winter in Oklahoma in the snow, and really just following common sense driving practices really helped. Lengthen your following distance, start stopping way before a light or stop sign. Take it easy. Give yourself extra time to get from point A to point B.
Watch out for people who forget their brakes don’t work at the red lights and stop signs.
Thanks Tyler. Real nervous about my commute tomorrow. Salem to Tigard. Landed my dream job and really dont want to call in after my first week. Going to probably have to take the new SUV to work tomorrow but thinking id rather crash my Accord
My experience is that studded tires are your best bet, but still not a guarantee at all. When driving on snow you can turn into the direction of a slide and you can regain traction. Not so on ice, even with awd. Inertia on a frictionless surface. Keep your speed down, increase stopping distance, and look out for shiny spots on the road. Love driving in snow, although other people scare me. Ice is another matter.
Thank you for all the replies! I really appreciate it.
I think a lesson learned this morning for a lot of drivers (and one I had a few years ago) if the temp is below lets say 38 or 37 anywhere on your trip, assume there is ice. You never know where the skies have cleared a bit and the temp has dropped. What happened this morning is people saw no snow on the ground, and figured things were just fine…
Leave plenty early
from looking at those maps, what do you think salem will recieve?
So that low that I mentioned in BC…that most certainly looks like it will be a player in our forecast…maybe that is our snow for Wednesday?
GFS 12z doesn’t even acknowledge it. Will be interesting to see how that changes on the 18z
My guess is snow in Clark Co. Changes to rain later this am…. Then back to snow…a la 85