November 2017 PNW Discussion Thread

[Kayla]

After Christmas.

 

End of Hanukkah.    

[luvssnow_spokane]

I'm thinking somewhere around the 20th - 23rd.

I sooo hope you’re right!!!!

[MossMan]

Christmas Eve at sunset.

[Phil]

I'm thinking somewhere around the 20th - 23rd.

New Years Eve. Arctic front moves through SEA @ 5:57pm on December 31st, rain changes to snow by 11:28pm as temperatures plunge from 56*F to 29*F over 6hrs.

 

Midnight high of 29*F, falling to 17*F by 10AM on January 1st while snow continues to fall. Snow ends by 4pm, skies clear overnight and temps plummet to 4*F by sunrise the next day.

 

Snowfall total @ SeaTac is 11.7". Next snowstorm is only three days away..00z ECMWF is a storm king repeat. Jim and Rob are throwing blizzard parties. Tim is downplaying. Dewey is above the fray.

[luvssnow_spokane]

New Years Eve. Arctic front moves through SEA @ 5:57pm on December 31st, rain changes to snow by 11:28pm as temperatures plunge from 56*F to 29*F over 6hrs.

 

Midnight high of 29*F, falling to 17*F by 10AM on January 1st while snow continues to fall. Snow ends by 4pm, skies clear overnight and temps plummet to 4*F by sunrise the next day.

I have never seen anything that extreme here ever. So I approve and ... I hope you’re sooo right!!

[Deweydog]

New Years Eve. Arctic front moves through SEA @ 5:57pm on December 31st, rain changes to snow by 11:28pm as temperatures plunge from 56*F to 29*F over 6hrs.

 

Midnight high of 29*F, falling to 17*F by 10AM on January 1st while snow continues to fall. Snow ends by 4pm, skies clear overnight and temps plummet to 4*F by sunrise the next day.

Sounds like -30c to me!

[Jesse]

New Years Eve. Arctic front moves through SEA @ 5:57pm on December 31st, rain changes to snow by 11:28pm as temperatures plunge from 56*F to 29*F over 6hrs.

 

Midnight high of 29*F, falling to 17*F by 10AM on January 1st while snow continues to fall. Snow ends by 4pm, skies clear overnight and temps plummet to 4*F by sunrise the next day.

 

Snowfall total @ SeaTac is 11.7". Next snowstorm is only three days away..00z ECMWF is a storm king repeat. Jim and Rob are throwing blizzard parties. Tim is downplaying. Dewey is above the fray.

Most believable winter forecast I’ve heard yet!

[Front Ranger]

We're about to embark on an incredible +PNA run. Anything above 300 is very high, and we're forecast to see several days near 400 or higher.

 

 

Here are -ENSO/neutral years that had major +PNA for at least a week in the Nov 25 - Dec 15 period, with the peak daily number.

 

1949 (+395 on 11/26)

1962 (+495 on 12/11)

1964 (+291 on 12/7)

1974 (+307 on 12/2)

1981 (+220 on 12/12)

1985 (+234 on 12/5)

1988 (+374 on 12/4)

1989 (+476 on 12/3)

1995 (+309 on 12/11)

2000 (+212 on 12/1)

2008 (+300 on 11/27)

 

The only ones that approached or surpassed the values we're expected to see are 1949, 1962, 1988, and 1989.

 

As you can see from the image above, we're also expected to have -NAO dominate over the next 10 days or so, though not as strong as the +PNA.

 

The years that saw NAO of at least -150 during their +PNA periods: 1949, 1962, 1981, 1989, 1995, and 2008.

 

1962 and 1989 are easily the best overall pattern matches to what we're seeing, in my opinion, followed by 1995 and 1981. Those are my top 4 analogs going forward, and a common theme is clear: blocky winters that favored cold in the East early, but cold shifting more west (including the PNW) later on.

[Gradient Keeper]

We're about to embark on an incredible +PNA run. Anything above 300 is very high, and we're forecast to see several days near 400 or higher.

 

4indices.png

 

Here are -ENSO/neutral years that had major +PNA for at least a week in the Nov 25 - Dec 15 period, with the peak daily number.

 

1949 (+395 on 11/26)

1962 (+495 on 12/11)

1964 (+291 on 12/7)

1974 (+307 on 12/2)

1981 (+220 on 12/12)

1985 (+234 on 12/5)

1988 (+374 on 12/4)

1989 (+476 on 12/3)

1995 (+309 on 12/11)

2000 (+212 on 12/1)

2008 (+300 on 11/27)

 

The only ones that approached or surpassed the values we're expected to see are 1949, 1962, 1988, and 1989.

 

As you can see from the image above, we're also expected to have -NAO dominate over the next 10 days or so, though not as strong as the +PNA.

 

The years that saw NAO of at least -150 during their +PNA periods: 1949, 1962, 1981, 1989, 1995, and 2008.

 

1962 and 1989 are easily the best overall pattern matches to what we're seeing, in my opinion, followed by 1995 and 1981. Those are my top 4 analogs going forward, and a common theme is clear: blocky winters that favored cold in the East early, but cold shifting more west (including the PNW) later on.

This is a great post!

 

Several of those years were huge Winters for us! Jan 1950!

[stuffradio]

We're about to embark on an incredible +PNA run. Anything above 300 is very high, and we're forecast to see several days near 400 or higher.

 

4indices.png

 

Here are -ENSO/neutral years that had major +PNA for at least a week in the Nov 25 - Dec 15 period, with the peak daily number.

 

1949 (+395 on 11/26)

1962 (+495 on 12/11)

1964 (+291 on 12/7)

1974 (+307 on 12/2)

1981 (+220 on 12/12)

1985 (+234 on 12/5)

1988 (+374 on 12/4)

1989 (+476 on 12/3)

1995 (+309 on 12/11)

2000 (+212 on 12/1)

2008 (+300 on 11/27)

 

The only ones that approached or surpassed the values we're expected to see are 1949, 1962, 1988, and 1989.

 

As you can see from the image above, we're also expected to have -NAO dominate over the next 10 days or so, though not as strong as the +PNA.

 

The years that saw NAO of at least -150 during their +PNA periods: 1949, 1962, 1981, 1989, 1995, and 2008.

 

1962 and 1989 are easily the best overall pattern matches to what we're seeing, in my opinion, followed by 1995 and 1981. Those are my top 4 analogs going forward, and a common theme is clear: blocky winters that favored cold in the East early, but cold shifting more west (including the PNW) later on.

I approve of 2008.

[MossMan]

Feels like something huge could be brewing!

[Front Ranger]

This is a great post!

 

Several of those years were huge Winters for us! Jan 1950!

 

Well...in 1949 the PNA crashed on 12/9 (and you'll notice it also peaked earlier on 11/26) and basically remained tanked until early February. Looks unlikely we'll see a pattern shift this year that soon. But you never know!

[snow_wizard]

We're about to embark on an incredible +PNA run. Anything above 300 is very high, and we're forecast to see several days near 400 or higher.

 

4indices.png

 

Here are -ENSO/neutral years that had major +PNA for at least a week in the Nov 25 - Dec 15 period, with the peak daily number.

 

1949 (+395 on 11/26)

1962 (+495 on 12/11)

1964 (+291 on 12/7)

1974 (+307 on 12/2)

1981 (+220 on 12/12)

1985 (+234 on 12/5)

1988 (+374 on 12/4)

1989 (+476 on 12/3)

1995 (+309 on 12/11)

2000 (+212 on 12/1)

2008 (+300 on 11/27)

 

The only ones that approached or surpassed the values we're expected to see are 1949, 1962, 1988, and 1989.

 

As you can see from the image above, we're also expected to have -NAO dominate over the next 10 days or so, though not as strong as the +PNA.

 

The years that saw NAO of at least -150 during their +PNA periods: 1949, 1962, 1981, 1989, 1995, and 2008.

 

1962 and 1989 are easily the best overall pattern matches to what we're seeing, in my opinion, followed by 1995 and 1981. Those are my top 4 analogs going forward, and a common theme is clear: blocky winters that favored cold in the East early, but cold shifting more west (including the PNW) later on.

 

A good number of those winters featured at least one really cold month...many with significant snowfall also.  Nature loves to do complete reversals.

[snow_wizard]

Should be 75 degrees at the ski resorts under that ridge

 

The ones that aren't passes perhaps.  The passes usually have a shallow layer of cold air flowing in from Central WA.

[Front Ranger]

Worth noting that 1962, 1981, 1989, and 1995 all saw -PNA dominate for most of January into February. That includes 1989-90, which even though it had a very -PNA January, didn't really get cold until February when the EPO finally went negative.

 

But given where we're at with solar and the October/November patterns, I think odds are much more in favor of getting cold in January, possibly late December. 

[Front Ranger]

A good number of those winters featured at least one really cold month...many with significant snowfall also.  Nature loves to do complete reversals.

 

Indeed.

 

You've mentioned many times how extremes beget extremes, and that's certainly evident when looking at these numbers. Years like 2011, 2007, 2000, 1999, 1975, 1974, etc just didn't see the same highly amplified patterns leading up to winter like we're seeing this year.

[Jesse]

Should be 75 degrees at the ski resorts under that ridge

Tim’s warming hut will be roasting.

[Gradient Keeper]

Keep an eye on the teleconnections indices forecast, primarily the PNA, EPO and look for them to turn negative 16th - 20th.

[Gradient Keeper]

00z ECMWF

 

Day 5

http://maps1.pivotalweather.com/maps/models/ecmwf/2017113000/120/500h_anom.na.png

[BLI snowman]

Indeed.

 

You've mentioned many times how extremes beget extremes, and that's certainly evident when looking at these numbers. Years like 2011, 2007, 2000, 1999, 1975, 1974, etc just didn't see the same highly amplified patterns leading up to winter like we're seeing this year.

 

Eh, November/December 2000 was pretty amplified.

[Jesse]

Eh, November/December 2000 was pretty amplified.

2000-01 is a sticky wicket. Had a lot of the trappings of what could have been the lead up to a great winter with a cold, blocky fall, but then it just sort of fell apart.

[Gradient Keeper]

Ridge nearing date line is more amplified than previous runs. For what it's worth, which is probably a nickel, perhaps a dime.

[HighlandExperience]

Tim’s warming hut will be roasting.

TT will post pictures of a frigid Duluth and skiing on 5 inches of ice crust.

[Gradient Keeper]

Day 6

http://maps1.pivotalweather.com/maps/models/ecmwf/2017113000/144/500h_anom.na.png

[Gradient Keeper]

Day 7

http://maps1.pivotalweather.com/maps/models/ecmwf/2017113000/168/500h_anom.na.png

[luvssnow_spokane]

Ridge nearing date line is more amplified than previous runs. For what it's worth, which is probably a nickel, perhaps a dime.

I’ll give you a penny for your thoughts

[Gradient Keeper]

Can't wait for days 8, 9, 10

[stuffradio]

Can't wait for days 8, 9, 10

We should skip day 9 because 7 8 9.

[ShawniganLake]

Can't wait for days 8, 9, 10

Ridge, ridgier, ridgyist

[Gradient Keeper]

Day 8

http://maps1.pivotalweather.com/maps/models/ecmwf/2017113000/192/500h_anom.na.png

[Gradient Keeper]

Day 9

http://maps1.pivotalweather.com/maps/models/ecmwf/2017113000/216/500h_anom.na.png

[Front Ranger]

Eh, November/December 2000 was pretty amplified.

 

True, of that bunch 2000 was the most blocky/amplified.

 

But it still wasn't quite on 2017's level. The upcoming +PNA will almost certainly be greater than any +PNA episode that fall, and the -EPO block we saw in late Oct/early Nov easily beats anything seen fall 2000.

[Front Ranger]

2000-01 is a sticky wicket. Had a lot of the trappings of what could have been the lead up to a great winter with a cold, blocky fall, but then it just sort of fell apart.

 

I thought 2000 was one of the better analogs back in October, but given how the pattern has evolved since then, I don't see it as a leading analog now. Couldn't have had a much more dissimilar November nationally.

[BLI snowman]

2000-01 is a sticky wicket. Had a lot of the trappings of what could have been the lead up to a great winter with a cold, blocky fall, but then it just sort of fell apart.

 

Yeah, things set up too far east early on and then that midwinter was a huge disappointment where basically nothing happened weatherwise. A rare combo of persistently dry weather and warm anomalies in January. 

[Gradient Keeper]

Day 10

http://maps1.pivotalweather.com/maps/models/ecmwf/2017113000/240/500h_anom.na.png

[Front Ranger]

Ridge actually weakens/de-amplifies quite a bit from day 8-10 on this run. 

[Jesse]

Yeah, things set up too far east early on and then that midwinter was a huge disappointment where basically nothing happened weatherwise. A rare combo of persistently dry weather and warm anomalies in January.

A certain 25 year old budding lawyer was enjoying some life changing cold anomalies in Omak that winter, if I recall.

[Gradient Keeper]

Ridge actually weakens/de-amplifies quite a bit from day 8-10 on this run. 

Yeah, seems to be a real outlier when compared to EPS, CMCE, GEFS.

 

6z GFS in 2 hours 22 minutes!

[Deweydog]

That's a low over the Aleutians!!!

[Deweydog]

A certain 25 year old budding lawyer was enjoying some life changing cold anomalies in Omak that winter, if I recall.

December was pretty cold.