December 2017 Long Range Disco

[frd]

Some changes  going on 

 

 

[mitchnick]

25 minutes ago, frd said:

Some changes  going on 

 

 

This is what they are talking about. Go to this link: http://www.geo.fu-berlin.de/en/met/ag/strat/produkte/winterdiagnostics/index.html

Now click on November 19, 2017 date; then click on "30hPa"; then scroll down to Days 9 & 10.

Pretty wacky

[frd]

26 minutes ago, mitchnick said:

This is what they are talking about. Go to this link: http://www.geo.fu-berlin.de/en/met/ag/strat/produkte/winterdiagnostics/index.html

Now click on November 19, 2017 date; then click on "30hPa"; then scroll down to Days 9 & 10.

Pretty wacky

Agreed , crazy 3 wave on that forecast 

[frd]

Nothing crazy but its something 

 

 

 

[cae]

1 hour ago, frd said:

Some changes  going on 

 

 

59 minutes ago, mitchnick said:

This is what they are talking about. Go to this link: http://www.geo.fu-berlin.de/en/met/ag/strat/produkte/winterdiagnostics/index.html

Now click on November 19, 2017 date; then click on "30hPa"; then scroll down to Days 9 & 10.

Pretty wacky

To extrapolate beyond that, you need Dennis Quaid's weather model.

https://www.youtube.com/kDwdDULiR6Q?start=21&end=26&version=3

 

[mitchnick]

42 minutes ago, frd said:

Nothing crazy but its something 

 

 

 

My guess is that he's referring to the same Euro prog mentioned by HM above. 

[poolz1]

12z GEFS continue the theme of 00z in building heights over the pole, AK and GL in the LR....after a brief relax period.  EPS has a similar look. Things have been a little jumpy lately so not completely sold...but the fact that blocking has already been forecasted and came to fruition gives a little more confidence that this isn't what we've experienced the past few years. 

[mitchnick]

Art, I'll take the day 16 GEPS for $1,000..............<insert bells and applause>...The Daily Double!

 

[mattie g]

5 hours ago, leesburg 04 said:

Ugh

Come on, man...we’ve got deltas and 3-waves.

[Vice-Regent]

16 minutes ago, mattie g said:

Come on, man...we’ve got deltas and 3-waves.

Yet nothing is yielded, sign of the times....for reals.

[frd]

 

The conversation in this thread is very interesting.

 

Some of my favorite weather mets stating the super negative NAO is over rated.

More of a driver for Europe.

I believe Bob mentioned the AO is more a driver for us here.  

 

Granted to me it seems East based, not our favored location here in the Mid Atlanitc region.

Sometimes they retrograde, will be cool to see what really happens the next 5 to 15 days in the NAO domain.   

 

 

[Bob Chill]

2 minutes ago, frd said:

 

The conversation in this thread is very interesting.

 

Some of my favorite weather mets stating the super negative NAO is over rated.

More of a driver for Europe.

I believe Bob mentioned the AO is more a driver for us here.  

 

 

The strongest correlation with snowfall in the MA is the AO and the majority of our storms over 4" happen with a -AO. The NAO is what typically drives big storms because it slows them down and allows prolific precipitation. Many times the AO/NAO move in tandem because they overlap with domain space. 

Generally speaking....and what is most important for our winters as a whole....is when the AO averages negative for DJF we usually do ok in the snowfall dept and also have colder than normal temperatures. 

Interestingly, the 12z EPS is now showing a fairly strong -AO d10-15. Goes right along with what the GEFS/GEPS are showing so we have consensus. It's nice to see the strat start to cooperate as well. To have a long duration/stable -AO, you typically need the strat and trop to work in tandem. A lot of things seems to be wanting to break in our favor right now.  

[frd]

39 minutes ago, Bob Chill said:

 

The strongest correlation with snowfall in the MA is the AO and the majority of our storms over 4" happen with a -AO. The NAO is what typically drives big storms because it slows them down and allows prolific precipitation. Many times the AO/NAO move in tandem because they overlap with domain space. 

Generally speaking....and what is most important for our winters as a whole....is when the AO averages negative for DJF we usually do ok in the snowfall dept and also have colder than normal temperatures. 

Interestingly, the 12z EPS is now showing a fairly strong -AO d10-15. Goes right along with what the GEFS/GEPS are showing so we have consensus. It's nice to see the strat start to cooperate as well. To have a long duration/stable -AO, you typically need the strat and trop to work in tandem. A lot of things seems to be wanting to break in our favor right now.  

I was hoping you chime in. 

Seems that the trend is for the blocking to move to the pole, from where is has been.

As you stated as well Bob, there seems to be a growing concensus of things coming together for this to happen,  and then possibly to hold in a while . December looking better and better.  Not to mention improving climo as well,  as we venture deeper into the month of December.  

[Bob Chill]

4 minutes ago, frd said:

I was hoping you chime in. 

Seems that the trend is for the blocking to move to the pole, from where is has been.

As you stated as well Bob, there seems to be a growing concensus of things coming together for this to happen,  and then possibly to hold in a while . December looking better and better.  Not to mention improving climo as well,  as we venture deeper into the month of December.  

The Dec AO can be decent clue for how winter will play out with snowfall. Statistically, an AO average of 1.2 or higher in Dec correlates with an 20% chance of above normal snowfall. An AO average below -1.2 correlates with a 50% chance of above normal snowfall. 

Another nice thing about a strong -AO in December is it can be very persistent. Almost 90% of Decembers with an AO average below -1.2 also feature a -AO in January. Right now it's starting to have that feel of a solid -AO December. Way too early to make a definitive statement but I see a lot of encouraging things happening right now. 

[poolz1]

@frd  I think we follow a lot of the same people on twitter.  Side note: Twitter is the devil and is the beginning of the end for civilization! lol But its great for weather/climate info...

Iv'e seen a lot of posting on the progressive flow regardless of the -AO/NAO due to the lack of the PAC cooperating. I am curious if as the season progresses and all things remain constant would there be a different surface map?  Is the main goal here in the MA to get a decent NPAC and -AO?  A -NAO being the icing on the cake for the biggies? 

 

[WxUSAF]

Certainly nice to see the high latitude blocking showing up on the guidance as we move into December. They’ve been bouncing around on the pattern of that blocking, but at least been fairly persistent in it being there in sole fashion. Also been a clear tendency for D7+ cold shots to turn into modestly below normal temps instead. Now of course the cold temps after thanksgiving are the next test of that pattern. Climo will help that as we get deeper into the season.  Either way, it seems likely that November temperatures will end up below normal. Mostly a question of whether it’s just one or 2° or more like 3+.

[mattie g]

1 hour ago, Vice-Regent said:

Yet nothing is yielded, sign of the times....for reals.

True. November climo sucks around here.

[CAPE]

New weeklies have a -AO look wire to wire, with a -NAO much of the time.

eta- NPAC looks fantastic. -EPO, and no sign of a trough out west until near the end of the run, which is early Jan.

lol could be some good times just ahead if this is even close to reality.

[Vice-Regent]

1 minute ago, C.A.P.E. said:

New weeklies have a -AO look wire to wire, with a -NAO much of the time.

I digress, it is early. You should be able to yield something in November with that kind of blocking.

[mitchnick]

9 minutes ago, C.A.P.E. said:

New weeklies have a -AO look wire to wire, with a -NAO much of the time.

Thanks.  Fwiw, and I can't vouch for his accuracy,  but Tombo over in the PHL site goes in depth here:

http://www.phillywx.com/topic/894-cfs-ggem-jma-and-euro-weeklies-thread/?do=findComment&comment=82820

[CAPE]

7 minutes ago, mitchnick said:

Thanks.  Fwiw, and I can't vouch for his accuracy,  but Tombo over in the PHL site goes in depth here:

http://www.phillywx.com/topic/894-cfs-ggem-jma-and-euro-weeklies-thread/?do=findComment&comment=82820

I think he is trying to get a bit too "atomic" for a super LR outlook, but a pretty good synopsis. I think the best use of the weeklies is to get a general idea of the big picture features, and the big picture looks pretty freaking good IMO.

[Bob Chill]

It's safe to say the CanSips is going to bust BIGLY

[mitchnick]

9 minutes ago, Bob Chill said:

It's safe to say the CanSips is going to bust BIGLY

If you recall,  all the models were looking bad near the end of the month,  then things changed and the blocking appeared in the medium range. If that change was a week to ten days earlier, I bet the monthly model progs would have been different. But I know that's pure speculation on my part. 

[CAPE]

Snapshot for NYE:

[Bob Chill]

2 minutes ago, mitchnick said:

If you recall,  all the models were looking bad near the end of the month,  then things changed and the blocking apeared in the medium range. If that change was a week to ten days earlier, I bet the monthly model progs would have been different. But I know that's pure speculation on my part. 

I totally agree with you. Ens started hitting on blocking literally the run after the CanSips came out. The verification scores for the ao/nao are terrible by day 14. There is no reliable way to predict it early in the season. Once it gets going one direction or the other skill improves quite a bit. But flipping from + to - or vice versa is typically sudden. 

[nj2va]

3 hours ago, C.A.P.E. said:

Snapshot for NYE:

Hello 2018!

[Vice-Regent]

So it begins, the flooding of the conus with PAC airmass.

[Ralph Wiggum]

5 hours ago, Vice-Regent said:

So it begins, the flooding of the conus with PAC airmass.

I'm not so sure about that. EPS, which is a better tool to use at that range over the op, argues against any sort of sustained PAC flow imo. In the map you posted, the Euro OP *may* also be suffering from it's usual bias of hanging too much energy back in the SW US. However, the GEFS also has some reflection of energy sitting out there as well though since it is not nearly as defined it doesn't pump the heights along the SE US as much as the Euro OP. Looks like a split flow entering the W Coast with the mean trof centered near the GL. If you take a look at the EPS you can see the ridge on the West Coast and the development of the -EPO happening which continues past D10 and yields much more of a flow across the NW territories and into the N Plains eventually spilling Eastward. Couple this with the -AO showing up and any PAC airmass "flooding the US" you note would be very transient. It's not a bad look showing up in the LR for now. 

[CAPE]

A somewhat more de-amplified, zonal look has been showing on the guidance for a while now. It appears to be a weakening signal with time though. Still, there will likely be a milder pattern for much of the US heading into the first week of December. There is no indication of a prolonged pacific firehose that I am seeing in the guidance, however.

From the 0z EPS: Following 4-5 days of slightly above average 850 temps, here are the advertised 850t anomalies at day 15:

[mattie g]

6 hours ago, Vice-Regent said:

So it begins, the flooding of the conus with PAC airmass.

Yeah...we should have expected a relentless press of Arctic cold all season long with no relaxation.