Part II, Thanksgiving week transient cold shot and the pattern beyond

[KEITH L.I]

The pattern is not going to be brutal cold...so I'm not sure where people are coming up with the idea of that. But some below avg temps are in store and more seasonable wx and perhaps some threats could come down the pipeline.

Look at Dec 1975 on how to get a below avg month with good snow with a +EPO/+AO/+NAO

do look similar

[ORH_wxman]

do look similar

You'd need a whole composite of the month. That is just one day on 12/10/75. But Dec '75 featured some flattish PNA ridging with a +EPO low height anomaly in AK and a bit of flat N ATL ridging with a +NAO.

[Mr Torchey]

Things look pretty intersting for those in the interior or north of the pike, I think it might be a tough go on the south coast in most of December, but that is normal. I am happy that normal to slightly below are coming back later this week time to get into the holiday spirit and with temps like that the interior certainly can cash in! Mid month looks sketchy to me, hopefully things can solidify for the holidays for all!

[Ottawa Blizzard]

the 0z GFS depicts an almost non stop torch right through to mid December.

[40/70 Benchmark]

the 0z GFS depicts an almost non stop torch right through to mid December.

Who cares....the value of a single deterministic OP run pales in comparison to that of the ensembles.

[Ottawa Blizzard]

Who cares....the vale of a single deterministic OP run pales in comparison to that of the ensembles.

are the ensembles looking positive?

[weatherMA]

the 0z GFS depicts an almost non stop torch right through to mid December.

[skierinvermont]

Usually a good sign that the writer doesn't really have a FIRM grasp on meterological synoptics is when the entire passage is comprised of nothing but index acronyms.

Or it's just a shorthand.

If anything the pattern change pushers in this thread are the one focusing too much on numerical values. Yes statistically the EPO goes slightly negative on the EC ensembles.. but it is not like any -EPO I would ever want for true sustained cold. No arctic connection whatsoever. It's basically a PNA ridge that noses up into southern Alaska temporarily. As I keep saying though it can still snow.

The GFS basically keeps the EPO firmly positive and average to above average temps over the next two weeks. EC ens pushing the ridging a little farther north and hence have a slightly colder look (and lower numerical EPO values).

And of course the tropical forcing suggests that this PNA spike/neutral EPO will likely be transient.

[toronto blizzard]

are the ensembles looking positive?

Yes they are

[OSUmetstud]

composite 500mb for december 1975.

[OSUmetstud]

500mb anomaly dec. 1975

[weathafella]

Or it's just a shorthand.

If anything the pattern change pushers in this thread are the one focusing too much on numerical values. Yes statistically the EPO goes slightly negative on the EC ensembles.. but it is not like any -EPO I would ever want for true sustained cold. No arctic connection whatsoever. It's basically a PNA ridge that noses up into southern Alaska temporarily. As I keep saying though it can still snow.

The GFS basically keeps the EPO firmly positive and average to above average temps over the next two weeks. EC ens pushing the ridging a little farther north and hence have a slightly colder look (and lower numerical EPO values).

And of course the tropical forcing suggests that this PNA spike/neutral EPO will likely be transient.

Again, few have pushed sustained pattern change. What we are seeing however is a massive shift from much above normal to normal. Normal climo max at BOS stays in the 40s until after 12/15. So it would have to be quite cold to produce and that's why it is relatively rare. But a change from way above normal to near or a bit above is massively different from the regime we've been in for the past 3 weeks.

[nzucker]

Again, few have pushed sustained pattern change. What we are seeing however is a massive shift from much above normal to normal. Normal climo max at BOS stays in the 40s until after 12/15. So it would have to be quite cold to produce and that's why it is relatively rare. But a change from way above normal to near or a bit above is massively different from the regime we've been in for the past 3 weeks.

The 0z GFS, to be honest, shows way above normal temperatures for the entirety of the run. It certainly did back off the cold significantly with the NAO being flat-out awful and troughing resuming in the West as that PNA ridge starts to retrograde.

[weathafella]

The 0z GFS, to be honest, shows way above normal temperatures for the entirety of the run. It certainly did back off the cold significantly with the NAO being flat-out awful and troughing resuming in the West as that PNA ridge starts to retrograde.

But the GFS ensembles for the same init do not agree and in fact the average d 6-10 is normal to below and 11-15 below. Nate, you are referring to one op run which is not supported by the ensembles.

[OSUmetstud]

The 0z GFS, to be honest, shows way above normal temperatures for the entirety of the run. It certainly did back off the cold significantly with the NAO being flat-out awful and troughing resuming in the West as that PNA ridge starts to retrograde.

The op is probably wrong. Ensembles show anomalies in the 0C to -1C range from Day 6 to 10 with -2C to -3C anomalies between Day 11 and Day 15.

[Logan11]

The op model bounces around from run to run. 18Z looked nicer so maybe I'll frame that one.

Some of it has to do with energy it digs deep into the Southwest....

The 0z GFS, to be honest, shows way above normal temperatures for the entirety of the run. It certainly did back off the cold significantly with the NAO being flat-out awful and troughing resuming in the West as that PNA ridge starts to retrograde.

[skierinvermont]

Again, few have pushed sustained pattern change. What we are seeing however is a massive shift from much above normal to normal. Normal climo max at BOS stays in the 40s until after 12/15. So it would have to be quite cold to produce and that's why it is relatively rare. But a change from way above normal to near or a bit above is massively different from the regime we've been in for the past 3 weeks.

You are right, I think we are basically saying the same thing. It's really what happens after Dec 5th or 10th we disagree on.

Op Euro looks pretty good.. guess I'll see ens in the morning.

[Logan11]

Certainly the huge ridge over AK is a positive at the end of the op ECM run. Maybe we would want it a bit further east, but sure beats the massive AK vortex.

You are right, I think we are basically saying the same thing. It's really what happens after Dec 5th or 10th we disagree on.

Op Euro looks pretty good.. guess I'll see ens in the morning.

[40/70 Benchmark]

Or it's just a shorthand.

If anything the pattern change pushers in this thread are the one focusing too much on numerical values. Yes statistically the EPO goes slightly negative on the EC ensembles.. but it is not like any -EPO I would ever want for true sustained cold. No arctic connection whatsoever. It's basically a PNA ridge that noses up into southern Alaska temporarily. As I keep saying though it can still snow.

The GFS basically keeps the EPO firmly positive and average to above average temps over the next two weeks. EC ens pushing the ridging a little farther north and hence have a slightly colder look (and lower numerical EPO values).

And of course the tropical forcing suggests that this PNA spike/neutral EPO will likely be transient.

Ok, no one is claiming that, nor do we need it.

As is often the case, semantics seem to have clouded our interpretations of each others' perspectives.

Any sustained cold waits until after mid month, imo.....at the earliest.

[CoastalWx]

That storm near the 6th as we were talking about appears to be going mild. This kind of goes back earlier to what we talked about the back and forth with temps. With the uncertainty in storm track, we run the risk of milder solutions, followed by cold again...that's the risk when you have no blocking.

I think we may relax and warm up again as the ridge retrogrades west towards the Aleutians, but loses amplitude. SE ridge would defintely flex if that happens. I suppose anything could happen, but there are signs it may get a bit milder again if that happens.

[40/70 Benchmark]

That storm near the 6th as we were talking about appears to be going mild. This kind of goes back earlier to what we talked about the back and forth with temps. With the uncertainty in storm track, we run the risk of milder solutions, followed by cold again...that's the risk when you have no blocking.

I think we may relax and warm up again as the ridge retrogrades west towards the Aleutians, but loses amplitude. SE ridge would defintely flex if that happens. I suppose anything could happen, but there are signs it may get a bit milder again if that happens.

Yay, more torch after a warm-wet\cold-dry rinse, repeat.

[CoastalWx]

Yay, more torch after a warm-wet\cold-dry rinse, repeat.

Who knows..maybe there will be some overrunning stuff.

[CoastalWx]

Yay, more torch after a warm-wet\cold-dry rinse, repeat.

I'm not suggesting it will be like that, just saying there is a chance of that. It's not a torch pattern whatsoever. Hopefully with the massive ridge in the GOA around day10, we can take advantage of it. I think overall it appears to be a gradient pattern, especially towards the end of the ensembles.

[Damage In Tolland]

2 shots at snow..Looks like the snowstorm next Saturday and then again on the 6th. That one on the 6th has the look of a possible interior icestorm

[CoastalWx]

2 shots at snow..Looks like the snowstorm next Saturday and then again on the 6th. That one on the 6th has the look of a possible interior icestorm

Hopefully the Saturday chance comes back on future guidance.

[Tropopause_Fold]

ec and the ec ens overnight runs really illustrate how long it can take for the cold to firmly establish itself sometimes...that UL in the SW makes it challenging as the flow really never wants to allow the cold to rush east. it takes until day 9/10 for truly "cold" air to make up and over the apps and into new england, despite being into the western GL by day 6.

that said, day 10 might be first time i've seen the ec ens actually have decently below average 850s into new england.

[Tropopause_Fold]

2 shots at snow..Looks like the snowstorm next Saturday and then again on the 6th. That one on the 6th has the look of a possible interior icestorm

that's positive thinking right there.

[CoastalWx]

ec and the ec ens overnight runs really illustrate how long it can take for the cold to firmly establish itself sometimes...that UL in the SW makes it challenging as the flow really never wants to allow the cold to rush east. it takes until day 9/10 for truly "cold" air to make up and over the apps and into new england, despite being into the western GL by day 6.

that said, day 10 might be first time i've seen the ec ens actually have decently below average 850s into new england.

That trough in the southwest makes an appearance again as the ridge retrogrades. It looks like the ridge may try to build a little more north into the Aleutians perhaps extrapolating past day15, but that is just a WAG for now. I still think we walk the line in mid month perhaps.

[ski MRG]

That trough in the southwest makes an appearance again as the ridge retrogrades. It looks like the ridge may try to build a little more north into the Aleutians perhaps extrapolating past day15, but that is just a WAG for now. I still think we walk the line in mid month perhaps.

Is WAG a meteorlogical term?lol

[CoastalWx]

Is WAG a meteorlogical term?lol

Wild Ass Guess...lol.