December 2016 Observations and Model Discussion for the Pacific Northwest

[Farmboy]

It involves some serious contortion exercises, deep meditation, prayer, and secret hand gestures.

LoL, that was funny.  

[Phil]

ECMWF is much better looking, but IMO is still digging too much energy back SW/offshore. Still handing off to the ULL/cutoff under the NPAC block.

[MossMan]

I'm going snowboarding at baker tomorrow for the first time in 8 years.... wish me luck

Be safe! Hopefully the pass will remain open for you!!

[BLI snowman]

12z Euro is now colder with the initial shot than the 12z GFS.

 

-15C 850mb temps for Portland and Seattle at 192 hours.

[IbrChris]

First time I can recall the models indicating an increasing likelihood of an arctic blast from 3 weeks out (Dec 15th Euro Weeklies - week 3 500 mb pattern).

I'll leave a few thoughts on the upcoming pattern change toward cold.

What I feel is pretty likely to occur:

• Cold temps at least as cold (and probably colder) than what we saw earlier in December.

What I feel may occur (reasonable likelihood of occurrence):

• Around a week of sub-40 highs with current modeling/vendor output favoring highs in the lower 30s and lows in the lower to mid 20s for the coldest days.
• At least one snow event with 1-3" around Portland in the next 7-10 days.

What I see as having a low likelihood of occurrence (10% or less):

• Mild or seasonable temps in the 8-14 day timeframe
• Historic cold with highs below 25 and lows below 15.
• Greater than 6" of snow in the next 7-10 days
   

Biggest snag in the pattern evolution seems to be between the Euro ensembles themselves...the 00z suite showed two very distinct solution camps with little in the way of middle-ground. The colder set largely reflects the GEFS progression. The mean itself is fairly meaningless in this context given it simply reflects an average between two divergent solutions. Personally I expect the Euro ensembles to trend colder and more in line with the GEFS during the next 24-48 hours of runs with both potentially settling around -10c (H8 temps) during the mid-late 6-10 day period.

[snow_wizard]

Bellingham area?

The analogs say it's likely you see some, but there's a danger you will get too deeply buried in the cold once it really sets in. 1963 is coming up fairly consistently and areas further south did better on that. Jan 1957 is one where it appears everyone did well.

[Deweydog]

12z Euro is now colder with the initial shot than the 12z GFS.

 

-15C 850mb temps for Portland and Seattle at 192 hours.

It's clearly leading the way!

[SilverFallsAndrew]

[IbrChris]

It's clearly leading the way!

 

Looks blastastic.

[Phil]

Day 8-10, definitely still struggling with that ULL/SW drag. At least it's closer to something sensible vs 00z.

[SilverFallsAndrew]

First time I can recall the models indicating an increasing likelihood of an arctic blast from 3 weeks out (Dec 15th Euro Weeklies - week 3 500 mb pattern).

 

I'll leave a few thoughts on the upcoming pattern change toward cold.

 

What I feel is pretty likely to occur:

• Cold temps at least as cold (and probably colder) than what we saw earlier in December.

What I feel may occur (reasonable likelihood of occurrence):

• Around a week of sub-40 highs with current modeling/vendor output favoring highs in the lower 30s and lows in the lower to mid 20s for the coldest days.
• At least one snow event with 1-3" around Portland in the next 7-10 days.

What I see as having a low likelihood of occurrence (10% or less):

• Mild or seasonable temps in the 8-14 day timeframe
• Historic cold with highs below 25 and lows below 15.
• Greater than 6" of snow in the next 7-10 days

   

Biggest snag in the pattern evolution seems to be between the Euro ensembles themselves...the 00z suite showed two very distinct solution camps with little in the way of middle-ground. The colder set largely reflects the GEFS progression. The mean itself is fairly meaningless in this context given it simply reflects an average between two divergent solutions. Personally I expect the Euro ensembles to trend colder and more in line with the GEFS during the next 24-48 hours of runs with both potentially settling around -10c (H8 temps) during the mid-late 6-10 day period.

 

Great analysis and along the lines of what I am thinking though you have much more knowledge to back it up than I do. What  you describe is fairly similar to early January 1993 or January 2007 as I mentioned earlier. I think the potential for something colder is there, but that is a reasonable forecast this far out. 

[IbrChris]

Great analysis and along the lines of what I am thinking though you have much more knowledge to back it up than I do. What  you describe is fairly similar to early January 1993 or January 2007 as I mentioned earlier. I think the potential for something colder is there, but that is a reasonable forecast this far out. 

Maybe Nelsen is rubbing off on me.

[snow_wizard]

Wow the ECMWF is cold. The magnitude of the block at day 9 is insane. Easily two weeks of cold if that verifies. This could be epic. It could make up for a whole lot of cold Januaries that have been missing in action since 1980.

[Timmy]

King euro is back

[Deweydog]

Great analysis and along the lines of what I am thinking though you have much more knowledge to back it up than I do. What you describe is fairly similar to early January 1993 or January 2007 as I mentioned earlier. I think the potential for something colder is there, but that is a reasonable forecast this far out.

 

Early January 1993 doesn't look like a particularly good match to me. Definitely some similarities to 2007 with the initial shot.

 

No snow for you.

[Heavy Snow]

At least there is a lot of cold air north and northeast of the boarder.  That is the best we can hope for to give us a chance.  Its been in a position for a while now that we haven't had for a while so I will take my chances on that.  There has been persistent blocking too which we haven't had.  So the pieces are there, or at least most of the pieces.  Odds are better than many winters.  All I can ask for.

 

Yeah, odds are better for us than in recent Winters.

[Goducks09]

When was the last time we saw this much model agreement?

[SilverFallsAndrew]

All of the big 3 are showing the reload potential as well...

[MR.SNOWMIZER]

When was the last time we saw this much model agreement?

Yesterday

.

[SilverFallsAndrew]

Early January 1993 doesn't look like a particularly good match to me. Definitely some similarities to 2007 with the initial shot.

 

No snow for you.

 

No not pattern wise with 93, but with observed temps...I don't have much January goodness to compare it to in my lifetime. 

[Deweydog]

When was the last time we saw this much model agreement?

January 2011, perhaps as far back as January 2005.

 

Hahahahahahahaha!!!

[luvssnow_spokane]

First time I can recall the models indicating an increasing likelihood of an arctic blast from 3 weeks out (Dec 15th Euro Weeklies - week 3 500 mb pattern).

 

I'll leave a few thoughts on the upcoming pattern change toward cold.

 

What I feel is pretty likely to occur:

• Cold temps at least as cold (and probably colder) than what we saw earlier in December.

What I feel may occur (reasonable likelihood of occurrence):

• Around a week of sub-40 highs with current modeling/vendor output favoring highs in the lower 30s and lows in the lower to mid 20s for the coldest days.
• At least one snow event with 1-3" around Portland in the next 7-10 days.

What I see as having a low likelihood of occurrence (10% or less):

• Mild or seasonable temps in the 8-14 day timeframe
• Historic cold with highs below 25 and lows below 15.
• Greater than 6" of snow in the next 7-10 days

   

Biggest snag in the pattern evolution seems to be between the Euro ensembles themselves...the 00z suite showed two very distinct solution camps with little in the way of middle-ground. The colder set largely reflects the GEFS progression. The mean itself is fairly meaningless in this context given it simply reflects an average between two divergent solutions. Personally I expect the Euro ensembles to trend colder and more in line with the GEFS during the next 24-48 hours of runs with both potentially settling around -10c (H8 temps) during the mid-late 6-10 day period.

Great analysis!! Thank you!... I hope to see a little more snow though. 

[Heavy Snow]

And how does one go about accomplishing this?  Give me a step-by-step, then we can apply your method to every time arctic goodies show up in the models.

 

To put us in the best situation possible, we need to lay the foundation and the background for an Arctic Blast to take place. Right now we have the ENSO, MJO, QBO, PNA, Typhoon Rule, La Nina, etc. all on our side. Many Arctic Blast that have been modeled of the recent past didn't have as many of these on their side and that's why they eventually didn't make it to the PNW. Right now we have almost everything on our side which increases the chances of this event taking place.

[Heavy Snow]

 

Still a long ways out but it looks good.

[westcoastexpat]

Snowing pretty heavily here right now.

[EA_TTD]

When was the last time we saw this much model agreement?

2008 immediately comes to mind.

[MR.SNOWMIZER]

January 2011, perhaps as far back as January 2005.

Hahahahahahahaha!!!

lucifer?

[Heavy Snow]

When was the last time we saw this much model agreement?

 

December 2008 immediately comes to mind.

[IbrChris]

To put us in the best situation possible, we need to lay the foundation and the background for an Arctic Blast to take place. Right now we have the ENSO, MJO, QBO, PNA, Typhoon Rule, La Nina, etc. all on our side. Many Arctic Blast that have been modeled of the recent past didn't have as many of these on their side and that's why they eventually didn't make it to the PNW. Right now we have almost everything on our side which increases the chances of this event taking place.

Amplify a ridge along 150-170 W (like in your signature images) and most of the time downstream development will cause a trough to dig along/just inland from the west coast. A bit of positive tilt to the ridge helps too. It's not so much that it's complicated for us to get cold, it's just not common to see a long-lived amplified block along 150-170 W at the same time the PV is on our side of the pole.

 

Snow on the other hand is fairly complicated, unless we are talking the typical overrunning transition snow event.

[Heavy Snow]

Amplify a ridge along 150-170 W (like in your signature images) and most of the time downstream development will cause a trough to dig along/just inland from the west coast. A bit of positive tilt to the ridge helps too. It's not so much that it's complicated for us to get cold, it's just not common to see a long-lived amplified block along 150-170 W at the same time the PV is on our side of the pole.

 

Snow on the other hand is fairly complicated, unless we are talking the typical overrunning transition snow event.

 

Yeah, that too. The Blocking is the most important thing. All of the models are in nice agreement of an amplified ridge in the sweet spot. I believe Snow will eventually come, probably with the Arctic Front and then a system sliding down later in the same week from the looks of it.

[Deweydog]

2008 immediately comes to mind.

Model agreement was ridiculous with that, even 8-9 days out.

[Gradient Keeper]

I sleep in and look what happens. Not too shabby suite of 12z runs. I have growing confidence the Euro is now handling the pattern correctly. 500mb progression with GFS/GEM/ECMWF is locking in. Finer details (How cold do we get exactly, moisture, reload potential) are uncertain. I would still like to see a TAD more over-water trajectory, but 12z runs are pretty fantastic, especially at 500mb. The GFS is a weather geeks dream. That was an amazing run. It shows the very real potential we have coming up IF the block holds out around 160 W with some tilt -> to it. Possible 2-3 week duration cold snap/blast. 00z runs tonight *should* be spectacular. We can start to watch the Ensemble mean dip colder I believe too. I see both Seattle, Medford NWS favoring the GFS. Seattle called the ECMWF last night the "odd man out/outlier" and other offices mentioned they were leaning towards the GFS, but wanted to wait before "buying" into the faster progression. I have to say I am extremely impressed with the GFS Op persistence and consistency for 3 days now. It has not blinked once. Onto 00z!

[Jesse]

Early January 1993 doesn't look like a particularly good match to me. Definitely some similarities to 2007 with the initial shot.

 

No snow for you.

 

I can still recall how stoically the arctic air limped in for that one.

 

One of these days we will get a real arctic front.

[snow_wizard]

The ECMWF snowfall map for New Years looks just like the WRF I posted earlier.  King County gets snow!

[Jesse]

Very good model trends this morning.

[snow_wizard]

I can still recall how stoically the arctic air limped in for that one.

 

One of these days we will get a real arctic front.

 

2007 was the best January event of this century for my area.  Coldest min temps, most snow, clear with snow on the ground for a while, snow while the cold was in place, etc.

[snow_wizard]

Good potential for frozen lakes with the coming cold since it has been cold for so long already.

[Deweydog]

I can still recall how stoically the arctic air limped in for that one.

 

One of these days we will get a real arctic front.

They're pretty rare down here.

[HighlandExperience]

The ECMWF snowfall map for New Years looks just like the WRF I posted earlier. King County gets snow!

I'll believe it when I see flakes flying!

[IbrChris]

Feel confident we'll see a downward shift on today's Euro ensembles....closer to the 00z GEFS.