Evolving winter storm threat Dec 13.14.15.16.17. Continental 'tumbler' may redevelop/Miller B

[Stormchaserchuck1]

Coming out of west-based strong -NAO block. In real time, I have seen this go for 5/5 in the last 5 times, and it's ~80-90% in the longer term (after the fact/theorized) we get a big storm,or close to it, as the west-based -NAO block is lifting out. 

 ^-NPH (east Pacific) developing on this 384hr model, and I have done research showing a 0.80-0.90 correlation jump with +/- anomalies at 40-45N recently(minus indexes) ,in unlikely areas, jumping to key regions (PNA). Our best pattern for snow on the east coast is a Gulf of Alaska low pressure.

^italics I think this favors a neutral or +PNA in that time. Could be a good mixture for a big snowstorm. 

That +400dm+ -NAO lifting out has been really strong correlation-indicator in real time. 

[40/70 Benchmark]

Yes, mid-month towards the holidays offers higher end potential.

Agreed.

[Stormchaserchuck1]

7 hours ago, 40/70 Benchmark said:

Yes, mid-month towards the holidays offers higher end potential.

Agreed.

I actually like the pattern after, +NAO/+PNA, probably better, if not for the high-tendency percentage of lifting out of -NAO. personal theory is that we do better for snowfall these days in +NAO.. -0.60 overall skew(neutral[neutral](1 being good -NAO, -1 being bad +NAO, -0.60 of that (NAOalone))

[Typhoon Tip]

mm ...I think the 13/14th is lit up some in the ensembles ( about a 1/3 of them) for a reason, too.   Not sure about the 17th -20th, but the period between the 10th and Christmas in general appears vulnerable for activity.  Suppressed ambient polar boundary pressed into heights lingering modestly positive in the deep south, yeah... an index modal change drawing the mid levels back N over that boundary in the means is quintessential H.A.   There was that in the 7th...9th but it seems to be correcting further out in time. 

We've been discussing elsewhere ... but moving an along an event spectrum from cutter --> overrunning --> more formulaic coastal spanning 10 days to two weeks mid month, isn't a bad idea.  Even if one of those verifies..

[40/70 Benchmark]

6 hours ago, Stormchaserchuck1 said:

I actually like the pattern after, +NAO/+PNA, probably better, if not for the high-tendency percentage of lifting out of -NAO. personal theory is that we do better for snowfall these days in +NAO.. -0.60 overall skew(neutral[neutral](1 being good -NAO, -1 being bad +NAO, -0.60 of that (NAOalone))

I mean mid month onwards...

[Stormchaserchuck1]

Kick this -PNA out of there.. 3 contours on the GOA low

[Damage In Tolland]

Is this the real Chucky?

[CoastalWx]

1 hour ago, Damage In Tolland said:

Is this the real Chucky?

 

[RUNNAWAYICEBERG]

He paid the $8, he’s a verified Chucky.

[MJO812]

Bump

[ice1972]

There’s no way you know this is happening….we’re not clown range fools in here

[Stormchaserchuck1]

STJ is actually really juicy

 

[Henry's Weather]

You and I think alike, SCC. I look forward to verification

[Stormchaserchuck1]

Look at this wave train

Maybe someone could run stats on how it goes PNA negative/neutral, coming out of >4SD -NAO (rain/snow?). Because the moisture will be there. 

[Stormchaserchuck1]

Here we go.. look at all this moisture

 

[Typhoon Tip]

This is admittedly unusually early, but it is intended for risk assessing, which 10 days is not obscene for that sort of effort.  Therein, it is time ... I feel it's worth it to start a more focused thread for the 13.14.15th of the December. 

The 9.10 (dates) event in the foreground is noted, and not intending to ignore that possibility.  However, that one may not actually time within the span of the western ridging, which is why ( ironically ) the better, given to better large scale synoptic scaffolding, is the 13.14.15 prospect - and why this thread is focused there. But again ... hmm, this is not intended to ignore 9.10 altogether.  Both have frankly been suggestive is statistical correlations for over a week of guidance monitoring ...  There is possibility ( among a plethora of them, frankly) 9.10 could 'steal' the show by slowing down and/or stalling due to the NAO exerting hemisphere, which would introduce wave spacing and a tussle in future guidance - cross that bridge.  

In the meantime, this for the overall rudimentary canvas being in place and is/has been well covered, while now ( and perhaps most important) the the Pacific relay has been changing in favor of a better showing of ridging in the west... Below, I have annotated the 18z GFS for explanation purposes only - although it's essence/principle did not deviate too significantly from the 12z re the period in question (13.14.15) it is too early in the ball game for deterministic slide into home base.

Perhaps as an homage to just how sensitive ( and volatile) the ambience is over eastern N/A, almost immediately upon the ridge above presenting, ...the operational models waste little time materializing these illustrations. 

For now, all three more dependable guidance sources flagging moderate to major cyclogen from the Del Mar to CC region 13.14.15, and I do not believe that is mere coincidence. It fits the footprint of the mass field modes/modalities:  

relaxing NAO    https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.gefs.sprd2.png

rising PNA  https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/pna.gefs.sprd2.png

It's an interesting time to observe how the models resolve a complex Pacific relay that is dynamic, into a realm that is being forced to slow down by the might of what's proving to be a rather 'immovable object' in the NAO west limb block anomaly.  

[Stormchaserchuck1]

-NAO rebuilds while strongly negative on models 3 times. v 384hr is +400dm still. Dec 21-24 looks like the window per 18z GFS ensembles. (PNA should be positive then too.. could be a big one)

[moneypitmike]

An event thread 8 days in advance.......is this a new record??????!!!!!!

[STILL N OF PIKE]

Just start one 3 weeks early on Xmas grinch system , it would be quite hilarious 

[Typhoon Tip]

Quick statement wrt to the model contention (EPS vs the GEFs...). 

The GFS lineage does not lend to its being a better performing tool during retrograde/slowing patterns.  

Even in recent years... have personally noted that it still routinely is sped up over all other guidance by mid range, and what starts out as a small deviation from consensus, and almost unseen ... aggregates out in time.  I've also noted that it's integrated colder heights are also deeper by small margins that grow in time ... By D10, it is almost always colder on the polar side of the ambient jet - for better or worse - comparing to its competing guidance sources. 

I realize the Euro has come under question, but ..the proof is in the here and now.  One model has been more stable than the other, and the other's instability fits the above problems that I strongly argue it still has - however subtle those may be in a point to point analysis.  Integration of tiny errors over 300 hours, matters...  It's bias is (likely...) at odds with the nature of the hemisphere during this next two weeks, and these wild very large scale mass field continuity performance issues that are empirically observable in the GFS/GEFs is exposing what I personally have always known. 

The GFS does better and is competitive if not better than the other guidance now, in open wave velocity soaked pattern types.

Take this information for what one will... I am not deviating from this thread's purpose just yet.

[UnitedWx]

The CMC certainly likes this time frame. Now I'm curious to see what the Euro has to say

[Typhoon Tip]

49 minutes ago, UnitedWx said:

The CMC certainly likes this time frame. Now I'm curious to see what the Euro has to say

Under present circumstances? It certainly is hard to describe the sweetness of that eye candy as an alternative to wet stench we’ve been forced to eat of the other guidance types.  

it may be of limited solace that this particular model run is really only day 5 to 7 with this (so it’s really on the front side of the 13.14.15 but it is still actually the same disturbance) and the reason why it’s limited solace is because this model has basically very limited predictive skill beyond D4s from what I’ve seen in the past.  I don’t know if that’s changed in recent years? I know it’s gone thru some upgrades recently. I apologize if that’s case and it’s improved. I seldom use thus tool at time frames greater than day 4 as trust hasn’t been tested. Lol there’s too many forecast methods available as it is…. 

Your sentiment about watching for the Euro is a good, particularly because it was midway between this and the GFS ND/SD abomination -  as of last night - tho trended the wrong way. 

That said… The threads purpose was still just for a risk assessment… The risk however still there
 

 

[Stormchaserchuck1]

Still looks pretty ontrack.. you might be surprised. Dec 17-20 and all.. 

-NAO in the midst of a wet pattern, The only wet -NAO/December was 1996. 11/12 were drier than average, since 1948. 

[STILL N OF PIKE]

2 minutes ago, Stormchaserchuck1 said:

Still looks pretty ontrack.. you might be surprised. Dec 17-20 and all.. 

-NAO in the midst of a wet pattern, The only wet -NAO/December was 1996.  11/12 were drier than average, since 1948. 

Fascinating that 11/12 -NAO December’s were dry . For Bos?

[Stormchaserchuck1]

3 hours ago, STILL N OF PIKE said:

Fascinating that 11/12 -NAO December’s were dry . For Bos?

St. Louis-east. very broad-strong general signal. we are wet St. Louis east this Dec

<- +NAO-correlation/both considered

[Stormchaserchuck1]

active/wet STJ

or a piece will lag behind/in future model runs split/for Dec 18-19(stronger piece)

 

[Stormchaserchuck1]

Active STJ

[codfishsnowman]

1 hour ago, Stormchaserchuck1 said:

Active STJ

Boy is this out there...my half and half will be out of code before this happens 

[dryslot]

Typically when the block relaxes, We've had some good snowstorms, I think this is a good range for the first siggy one in the Northeast.

[Stormchaserchuck1]

Stronger the +PNA.. the more south.. I think the -EPO won't be a strong, and we'll see a general Aleutian low for ~10 days starting on this day

Obviously, these models correlate at 0.80-0.85, but that's the way it will adjust