December 2014 Observations for the Pacific Northwest

[VancouverIslandSouth]

Seeing lots of moderation in Dewpoints tonight from about -13C (8.6F) early in the morning to -5C (23F) now, yet temperatures are dropping off quicker now with the lack of wind. Downsloping winds have totally died out now and 925mb temperatures will be above freezing in about 12 hours so the moderation will continue through to the weekend. Wouldn't be surprised to see widespread frost tomorrow. I'll be happy to see this airmass pass; without snow the cold is just an inconvenience without the fun of a transformed landscape: chapped lips, higher heating costs, and for those of us with potted plants it's a pain because they are more prone to freezing solid without insulating snow cover (my attempts at artificial covers were thwarted by the nasty winds).

 

I do feel there has been a strong tendency in the pattern of the past couple years to want to place a ridge up against the West Coast whenever the pattern becomes amplified, not sure what exact mechanism is at play here but it's made for some uneventful outcomes in events that had decent potential. Makes for an interesting contrast with 2010/2011 where I seem to remember there was a tendency for the ridge to pop up a little too far to the West rather than the East yet it produced one of our most interesting winters of recent times. Next window for a pattern transition looks like Jan 5-10th so it'll be interesting if we can squeeze something out of that, even a marginal half day snow event would be nice at this point.

[FroYoBro]

Nothing showing up on 00z operational runs tonight.... IF anything does it won't be until tomorrow or Thursday.

Yep...

[Guest Winterdog]

They will probably clear before sunrise so I think we will still see a nice drop. Currently 22 here.

Thanks for consoling me but I was kind of trolling with that post I guess. The clouds don't bother me that much since I have such low expectations for this fleeting cold spell. I do expect to bottom out somewhere in the high teens though which is not too bad.

[SilverFallsAndrew]

Pdx stuck at 29 tho their wind has really slacked off.

[SilverFallsAndrew]

I think eugene and sle are headed for the teens tonight.

[VancouverIslandSouth]

Nothing showing up on 00z operational runs tonight.... IF anything does it won't be until tomorrow or Thursday.

 

The absence of a strong low in and around the Bering Sea showing up in the model runs for the foreseeable future is nice. It doesn't result in anything interesting at face value, but one take awhile is that we don't end up with a stagnant slow moving pattern. Things look to become more "active" over the next week and a half with no single feature dominating the pattern in the North Central/East Pacific.

[FroYoBro]

Like Andrew said, the winds are completely dying here. Should be cold. 26 right now. Coldest of the winter so far. 

[Front Ranger]

The high at Denver was 1 today.

 

With a low of -19 this evening. That ties the -19 seen in Feb 2014, which was the coldest temp since Dec 1990.

 

It's been an impressive run of Arctic outbreaks around here lately.

[bainbridgekid]

With a low of -19 this evening. That ties the -19 seen in Feb 2014, which was the coldest temp since Dec 1990.

 

It's been an impressive run of Arctic outbreaks around here lately.

Hasn't been a ton of snow there lately though has there?

[Timmy]

Headed for the teens in town tonight (scappoose), already at 22, which was the low last night. In timber, just west of here near vernonia, it's 17, may hit single digits there.

 

High of 27 here and down to only 22 with wind still here.

[bainbridgekid]

I think eugene and sle are headed for the teens tonight.

McChord in Tacoma is headed for their 11th low in the teens already this winter.

 

Not sure how many they average per Winter, but that seems pretty darn good before January has even started.

[BLI snowman]

Hasn't been a ton of snow there lately though has there?

 

Denver's done pretty badly with snow since 2009-10. 

[BLI snowman]

It's actually a rare December that has zero lowland snowfall west of the Cascades from B.C. on down. 2011 and 1999 are the only other ones in the last 20 years, and now we can add 2014 to the list. Just an observation...

[Front Ranger]

Hasn't been a ton of snow there lately though has there?

 

This winter has got off to a very slow start, though we've made some headway the last week. There's 7" on the ground here now.

 

Overall, the last few winters have seen about average snowfall for the area. 2012-13 was a little above, last winter a little below.

[Front Ranger]

Denver's done pretty badly with snow since 2009-10. 

 

You can't really go by their numbers to judge the metro area. They get less than pretty much everyone, and their new location is not as snowy as the locations their long term average comes from.

 

Look at Boulder's numbers the past few winters - you'll see they've been easily above average overall and have little correlation to DEN. And I live closer to Boulder than the airport.

[westiztehbest]

I see the 00z GFS trended colder for this weekend.  No thaw that the 12z runs where showing for Monday. 

[Dan the Weatherman]

Seeing lots of moderation in Dewpoints tonight from about -13C (8.6F) early in the morning to -5C (23F) now, yet temperatures are dropping off quicker now with the lack of wind. Downsloping winds have totally died out now and 925mb temperatures will be above freezing in about 12 hours so the moderation will continue through to the weekend. Wouldn't be surprised to see widespread frost tomorrow. I'll be happy to see this airmass pass; without snow the cold is just an inconvenience without the fun of a transformed landscape: chapped lips, higher heating costs, and for those of us with potted plants it's a pain because they are more prone to freezing solid without insulating snow cover (my attempts at artificial covers were thwarted by the nasty winds).

 

I do feel there has been a strong tendency in the pattern of the past couple years to want to place a ridge up against the West Coast whenever the pattern becomes amplified, not sure what exact mechanism is at play here but it's made for some uneventful outcomes in events that had decent potential. Makes for an interesting contrast with 2010/2011 where I seem to remember there was a tendency for the ridge to pop up a little too far to the West rather than the East yet it produced one of our most interesting winters of recent times. Next window for a pattern transition looks like Jan 5-10th so it'll be interesting if we can squeeze something out of that, even a marginal half day snow event would be nice at this point.

This is the same persistent ridge that has been primarily responsible for California's severe drought the last 2-3 years.

[ShawniganLake]

Seems like people are getting a little desperate for some snow around here.  All I can say is that things could look a lot less promising for January than they do right now.  I still quite like the chances for some type of snow event before mid-month.  Last year at this time January was looking like a write-off, and it ended up being one. 

[ShawniganLake]

http://www.wetterzentrale.de/pics/MT8_Vancouver_Kanada_ens.png

 

Not great, but not bad.  quite a few cold members in the longer range.  Interesting to see the mean drop down to -5C this weekend.  Havent given up on some snow up here this weekend. 

 

 

http://www.wetterzentrale.de/pics/MT8_Seattle_USA_ens.png

http://www.wetterzentrale.de/pics/MT8_Portland_Oregon_USA_ens.png

[Front Ranger]

The 0z GFS ensembles still indicate western troughing is likely for day 10+, but it's not a strong signal. Seems to be a lot of spread.

 

EDIT: And there you have them, right above.

[ShawniganLake]

Canadian Ensemble has also been indicating the likelihood of western troughing in the long range.  http://www.tropicaltidbits.com/analysis/models/gem-ens/2014123012/gem-ens_z500a_namer_51.png

[SilverFallsAndrew]

The ensembles are encouraging

[Gradient Keeper]

00z GFS Ensembles 850mb Temps
Yet again Mean temp drops below 0c around the 9th or 10th. This run features very few warm members and a lot more in the -5c to -10c range. Interesting. Seattle is just a bit colder yet. Hmmm....

 

It's getting chilly outside. 26.1, dewpoint 9, east wind has increased now 15-25 G 30+

[SilverFallsAndrew]

PDX has lost the E wind as of 1am and has dropped to 25. SLE and EUG continue to have a bit of a breeze and are hanging in the low/mid 20s. A lot of teens already in outlying areas. It would be nice to see widespread teens with the major stations, could get close.

 

Some of the stations in the Willamette Valley below 1000' currently in the teens

 

Colton 15

Liberal 16

Silverton 17

Lebanon 18

Sweet Home 18

Estacada 19

 

Scappoose up north on the Columbia River is at 19 as well.

[Gradient Keeper]

6z NAM HR 84

This is a bit interesting. Appears to me our offshore ridge may merge with the Aleutian Block. If so, that shortwave may dig down the BC coast....First run to not show that nagging shortwave bombarding the block flattening it. This is what I was alluding to with my analysis last Evening.

 

 

 

 

 

[ShawniganLake]

Another excellent write up by Jay! I have a great feeling that what is currently being shown in the model world is not going to be the final outcome. The first half of January might just end up being quite fun for us!

Looking at the 6z nam it seems like that positive trend may be continuing. Looks to me like the area of low pressure north of Hawaii is wanting to slip back south, keeping it and the short wave south of Alaska as separate entities. This could be important in maintaining a stronger block.

[ShawniganLake]

6z NAM HR 84

This is a bit interesting. Appears to me our offshore ridge may merge with the Aleutian Block. If so, that shortwave may dig down the BC coast....

First run to not show that nagging shortwave bombarding the block flattening it. This is what I was alluding to with my analysis last Evening.

 

nam_npac_084_500_vort_ht_l.gif

 

Looks quite a bit better.

[Gradient Keeper]

Looks quite a bit better.

Yessir

[MikeInEverett]

Looks like the GFS is starting to jump on board a little bit

I may be wrong though

[Gradient Keeper]

I just viewed both Op/Parallel through HR 132 and it looks like the cold trough gets a bit closer to us with a little more favorable ridge placement/configuration....The Yukon high slides further south into BC also... it's real close to a back door shot into Fraser/Columbia Basin.

[SilverFallsAndrew]

Pdx down to 22. A rare night where pdx is taking advantage of their low dp.

[SilverFallsAndrew]

To bad the clouds messed with the cooling. Pdx did hit 21 though.

 

Just landed in Denver. Looks cold!

[MossMan]

Currently 20 here.

[Phil]

Unless it will benefit us over here in the PNW, please do not post about it.

 

If it does, please explain how.

Do you read my posts? Because you've asked me to explain this multiple times, and I've done so multiple times.

 

Long story short, the blasts in 1968-69 and 2006-07 were both aided by PV breakdowns.

[MR.SNOWMIZER]

That shortwave on Saturday coming down the bc coast might be a game changer. Looks like the models are trending better for us.

[Phil]

Phil, could you explain how this map might benefit us over here on the west coast.

A strong PV is a detriment to meridional motion because momentum transfer is reduced..generally a +EPO/+NAO is favored under a strong, barotropic PV.

 

Recently, the PV has gone baroclinic as tropically-forced wave driving has increased..however, the PV was still strong enough to beat back the wave-breaking over the NATL and consolidate lower-level vorticity in the NAO domain..so when the PNA retrograde tries to occur, that vorticity will not want to do the same..

 

The PV is about to get the kibosh, so we'll see how low level wave tendencies respond. This usually lags by 1-3 weeks (I'm thinking we wait 15-20 days).

[Prairiedog]

Traveling to Winthrop .  I was surprised over how NOT cold the Columbia Basin was yesterday.  30-32f through the Gorge, same for the Yakima Valley.  Only cold spots were the passes.  Ellensburg was only slightly colder at 28f when we went through around 3pm. Satus was 16f and Blewett Pass was 14f.  Only places with snow cover were the passes.  Leavenworth was chilly at 20f at 4pm (9f this am) and about 4-5" snow.  Felt like winter there.  But overall it just wasn't cold at all in the basin.  Very little wind  overall in the Gorge yesterday too.  Spent the night in Leavenworth, heading to Winthrop this am.  Currently 6.5f but even there looks to moderate into the mid 20's but at least they have good snow on the ground. 

[Phil]

Remember how Phil said that the models will disagree until about 2-3 days out? Maybe he's onto something.

Unfortunately, upstream wave synchronization is pure s**t right now thanks to the failed -NAO attempt. The PNA retrograde will occur, but you won't have enough wave driving to do much out there because all the potential vorticity is locked in the +NAO.

[MossMan]

A strong PV is a detriment to meridional motion because momentum transfer is reduced..generally a +EPO/+NAO is favored under a strong, barotropic PV.

 

Recently, the PV has gone baroclinic as tropically-forced wave driving has increased..however, the PV was still strong enough to beat back the wave-breaking over the NATL and consolidate lower-level vorticity in the NAO domain..so when the PNA retrograde tries to occur, that vorticity will not want to do the same..

 

The PV is about to get the kibosh, so we'll see how low level wave tendencies respond. This usually lags by 1-3 weeks (I'm thinking we wait 15-20 days).

Thanks Phil! Seems quite complex, and way out of my scope of atmospheric knowledge so thanks for explaining!

[MossMan]

Do you read my posts? Because you've asked me to explain this multiple times, and I've done so multiple times.

 

Long story short, the blasts in 1968-69 and 2006-07 were both aided by PV breakdowns.

I was still 8 years from being born in 68-69 but my dad tells me it was quite the snow! He showed me pictures of his place in Edmonds and it looked like quite the snow depth! He had a pic of his 1965 Chevelle all chained up and still stuck half way down the driveway. With the 06-07 (Great year for my area between the Nov event and the Jan event) it seemed like there were hints of very little in the way of snowfall leading up to that event, but my area ended up doing quite well with almost a foot of snow falling and the lake freezing pretty solidly.