Thanksgiving week transient cold shot and the pattern beyond

[weathafella]

12/10 the change begins. It is complete by 12/25. All still on schedule.

[Logan11]

1988 did have a lot of cold in December, but we could never buy a good storm track that winter. Cold never mixed with moisture.

....

still an exceptionally strong signal, and three of the 7 years are Ninas. 56-57, 71-72, and 88-89 which are similar to the other 4 (warm overall, but 56-57 and 88-89 have a stripe of cold across the northern tier)

That's why I said I'd tone it back a bit especially in the northern plains where things could go either way because of the -PDO/Nina signal for cold. But otherwise the Nina signal matches well with the stratosphere signal for warmth strongest over the SE US.

[skierinvermont]

1988 did have a lot of cold in December, but we could never buy a good storm track that winter. Cold never mixed with moisture.

....

Sorry that was a typo when I said 88-89 had a stripe of cold, I meant 71-72. 88-89 was a torch for most of the US west of the rockies in Dec+Jan mean (more moderate in the northeast).

[weathafella]

still an exceptionally strong signal, and three of the 7 years are Ninas. 56-57, 71-72, and 88-89 which are similar to the other 4 (warm overall, but 56-57 and 71-72 have a stripe of cold across the northern tier)

That's why I said I'd tone it back a bit especially in the northern plains where things could go either way because of the -PDO/Nina signal for cold. But otherwise the Nina signal matches well with the stratosphere signal for warmth strongest over the SE US.

56-57 and 71-72 could be good analog years.

How can you call a sample size any scientist would laugh at an exceptionally strong?

[weathafella]

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How can you call a sample size any scientist would laugh as an exceptionally strong?

[skierinvermont]

How can you call a sample size any scientist would laugh at an exceptionally strong?

All 7/7 are warm. That's actually a decent SS. We always have some SS issues in meteorology.

I can also expand the sample size as in my other thread and the signal persists. Check out the NAO thread. The 30 coldest November stratospheres had a Dec-Jan AO that is nearly +2 higher than the 30 coldest. When the stratosphere remains cold into December, the disparity grows to +3. How is a sample size of 60? This is a very strong signal for a +AO dec-jan, which means warmth centered in the SE US.

That composite was only of the 7 closest matches. (exceptionally cold stratosphere over Russia).

[Organizing Low]

No kidding Logan. I'm starting to suspect we may have a torch December. Our only hope now is that there is a flip towards the end of December similar to December 1993. I note how a similar brief cold shot occurred in my area (Toronto/Ottawa) around november 20,1993 and how the record low in Fairbanks today was set in 1993.

jerry FTW

[ski MRG]

12/10 the change begins. It is complete by 12/25. All still on schedule.

I like your new mantra.

[weathafella]

All 7/7 are warm. That's actually a decent SS. We always have some SS issues in meteorology.

I can also expand the sample size as in my other thread and the signal persists. Check out the NAO thread. The 30 coldest November stratospheres had a Dec-Jan AO that is nearly +2 higher than the 30 coldest. How is a sample size of 60?

That composite was only of the 7 closest matches. (exceptionally cold stratosphere over Russia).

But it's exactly why the long range fail rate is high. It is not scientifically sound. We probably have had many more but not verifiable with modern measuring techniques.

[ski MRG]

Drop a few of these into your buns.

LOL! WHY a 2 bunner? You know it's going to happen. I won't be surprised if it happens sooner than many think.

[Jonger]

12/10 the change begins. It is complete by 12/25. All still on schedule.

Let's hope it doesn't take that long.. in my neck of the woods that's 1/4th of the winter lost.

Sent from my PG86100

[skierinvermont]

But it's exactly why the long range fail rate is high. It is not scientifically sound. We probably have had many more but not verifiable with modern measuring techniques.

Yes there is always uncertainty, but 7/7 is a decent sample size and it is complemented by the fact that since 1950 cold Nov stratosphere have had a an AO +2 greater than warm nov stratospheres (grows to a difference of +3 if stratosphere remains cold into december). Plus the causation is there.

That is why I've said elsewhere the chance of a +AO in dec-jan is 75% (not 100%). Always uncertainty.

[OKpowdah]

12/10 the change begins. It is complete by 12/25. All still on schedule.

I would like to see the long range Euro and GEFS start to become more adamant for a pattern change by the end of this week, since they're usually a little too quick to pull the trigger. On the other hand, definitely noteworthy the ludicrous speed of the MJO wave right now. It's blasted through phase 7 in ONE DAY, and is still a coherent wave

[Ottawa Blizzard]

I can say one thing, i don't have much faith in Joe Bastardi's forecast for a cold (although not as cold as last December) December.

[Ginx snewx]

I would like to see the long range Euro and GEFS start to become more adamant for a pattern change by the end of this week, since they're usually a little too quick to pull the trigger. On the other hand, definitely noteworthy the ludicrous speed of the MJO wave right now. It's blasted through phase 7 in ONE DAY, and is still a coherent wave

Am I missing something?, GFS ENS 6 Z continues the first week of DEC change.

[CoastalWx]

Am I missing something?, GFS ENS 6 Z continues the first week of DEC change.

Euro ensembles really aren't on board yet. They have us cooling down, but still zonal flow and above normal. I wouldn't call it a pattern change based on that.

[weathafella]

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Let's hope it doesn't take that long.. in my neck of the woods that's 1/4th of the winter lost.

Sent from my PG86100 <b></b>

Hey Jonger 1150, are. You the same guy from MI who used to post on eastern years ago?

[CoastalWx]

New 12z ensembles are definitely bring the vortex back into ne Asia and have a nice trough into the eastern US. However, it is the GFS ensembles at the end of their range. Would be nice if it verified.

[Jonger]

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Hey Jonger 1150, are. You the same guy from MI who used to post on eastern years ago?

Yes sir.... Been hanging out at a Michigan forum, but its dead right now. Many of those posters are here as well.

Sent from my PG86100

[weathafella]

Euro ensembles really aren't on board yet. They have us cooling down, but still zonal flow and above normal. I wouldn't call it a pattern change based on that.

That suggests to me that an equal number of members change with about the same number keeping the AK vortex meaning out to zonal?

[OKpowdah]

Am I missing something?, GFS ENS 6 Z continues the first week of DEC change.

1) Continues? It's not been a consistent forecast ... the 00z GEFS is not as favorable

2) It's not what I would call a solid pattern change. There are still below normal heights over Alaska and all of the AO domain. If anything, that would end up being a transient period of cooler temperatures, before the +EPO blasts the Pacific jet over the weak +PNA ridging again.

[ORH_wxman]

still an exceptionally strong signal, and three of the 7 years are Ninas. 56-57, 71-72, and 88-89 which are similar to the other 4 (warm overall, but 56-57 and 71-72 have a stripe of cold across the northern tier)

That's why I said I'd tone it back a bit especially in the northern plains where things could go either way because of the -PDO/Nina signal for cold. But otherwise the Nina signal matches well with the stratosphere signal for warmth strongest over the SE US.

SE ridge is def going to be there I think. I don't like the warm phase pacific analogs though and there are several of them in there. Those analogs will tend to want to suppress the Aleutian ridge...you can clearly see the more amplified Aleutian ridge and its effect on northern tier temperatures in the cold phase Nina analogs like '56-'57 and '71-'72.

[Amped]

Looks like winter is only 10 days away.

[Ginx snewx]

1) Continues? It's not been a consistent forecast ... the 00z GEFS is not as favorable

2) It's not what I would call a solid pattern change. There are still below normal heights over Alaska and all of the AO domain. If anything, that would end up being a transient period of cooler temperatures, before the +EPO blasts the Pacific jet over the weak +PNA ridging again.

I disagree the GEFS has consistently pointed towards a more normal regime and that is a pattern change from above normal.

[skierinvermont]

SE ridge is def going to be there I think. I don't like the warm phase pacific analogs though and there are several of them in there. Those analogs will tend to want to suppress the Aleutian ridge...you can clearly see the more amplified Aleutian ridge and its effect on northern tier temperatures in the cold phase Nina analogs like '56-'57 and '71-'72.

Agree - for that reason I would tone things back a bit.

In addition to 56-57 and 71-72 there is also 07-08 which is a good match in terms of the very cold stratosphere and the ENSO/PDO state. 88-89 only matches in terms of ENSO. Hopefully the ENSO/PDO signal prevents us from having an 06-07 type dec-jan.

99-00 did have the cold stratosphere -PDO -ENSO so it is still possible to torch the northern plains even with the -PDO -ENSO. Maybe you can exclude 99-00 because it was the start of the -PDO or was following the super-Nino but I don't know how much causative sense that makes. Do you know of any good reasons 99-00 was so warm in the northern plains (besides the cold stratosphere)?

[CoastalWx]

That suggests to me that an equal number of members change with about the same number keeping the AK vortex meaning out to zonal?

Spaghetti plots are all over the place as you would expect 360+ hrs out, but the mean wants to keep lower heights towards the kamchatka peninsula. It's likely too fast in this change, but at least it didn't get worse. I don't really take much stock into an hr 360 GEFS prog, but the key would be to watch if both the GFS and EC try to bring this closer and closer...like towards d10. Sometimes on the ensembles, the change is always at hr 360 or 384 and it takes 2+ weeks for the pattern to finally come inside 10 days.

[CT Rain]

12z GEFS definitely looks better by day 15.

[Logan11]

I think there will be plenty of conflicting signals until we get around a week out from the real pattern change. So the met's in here (being naturally cautious as per their training) can't forecast it for awhile. But weenies can if they want.

I disagree the GEFS has consistently pointed towards a more normal regime and that is a pattern change from above normal.

[Logan11]

71-72 saw the massive two foot Thanksgiving Noreaster in the Kocin "near miss" section. The first snowstorm that I can remember specifically. But I dunno how that month was overall or if that storm was an oasis in a sea of mild.

Agree - for that reason I would tone things back a bit.

In addition to 56-57 and 71-72 there is also 07-08 which is a good match in terms of the very cold stratosphere and the ENSO/PDO state. 88-89 only matches in terms of ENSO. Hopefully the ENSO/PDO signal prevents us from having an 06-07 type dec-jan.

99-00 did have the cold stratosphere -PDO -ENSO so it is still possible to torch the northern plains even with the -PDO -ENSO. Maybe you can exclude 99-00 because it was the start of the -PDO or was following the super-Nino but I don't know how much causative sense that makes. Do you know of any good reasons 99-00 was so warm in the northern plains (besides the cold stratosphere)?

[40/70 Benchmark]

I think there will be plenty of conflicting signals until we get around a week out from the real pattern change. So the met's in here (being naturally cautious as per their training) can't forecast it for awhile. But weenies can if they want.

Except for scooter.