December Medium/Long Range Discussion

[CAPE]

10 minutes ago, Ralph Wiggum said:

Just mentioned this in my home forum. Ens means are east-based. That is one way we could waste the good pattern looks on the ops. Unless you have a stable boat and head East.

This is definitely not the ideal place for the +height anomalies to be focused. It is workable though, as long as the Pacific is serviceable, and that is going to be variable. As is typically the case, timing and luck will be required. Also just because the means show the NA ridge generally further east than ideal, that doesn't mean it wont reside further NW at times. So again, timing.

[frd]

27 minutes ago, Ralph Wiggum said:

Just mentioned this in my home forum. Ens means are east-based. That is one way we could waste the good pattern looks on the ops. Unless you have a stable boat and head East.

Again not sure SSTs in NW Atlantic are responsible. I recall Blue Wave in the New York Forum doing a post back in the late summer where he mentioned the SST pattern over the Northwest Atlantic was responsible for the Western Atlantic Ridge being displaced further north this year versus further south . Wondering if it is still a factor.  Is it at Play here  again here with the Greenland block.

[Ralph Wiggum]

7 minutes ago, CAPE said:

This is definitely not the ideal place for the +height anomalies to be focused. It is workable though, as long as the Pacific is serviceable, and that is going to be variable. As is typically the case, timing and luck will be required. Also just because the means show the NA ridge generally further east than ideal, that doesn't mean it wont reside further NW at times. So again, timing.

Yes. And if you believe the means it anchors in and meanders around the general NAO region. So hopefully as you said timing and luck can play a role when it ventures into the more favorable areas. GFS op is eye candy wrt HL blocking the entire run and even becomes more favorable farther out. But alas....op at range so salt grains and all that jazz.

[JakkelWx]

9 minutes ago, CAPE said:

This is definitely not the ideal place for the +height anomalies to be focused. It is workable though, as long as the Pacific is serviceable, and that is going to be variable. As is typically the case, timing and luck will be required. Also just because the means show the NA ridge generally further east than ideal, that doesn't mean it wont reside further NW at times. So again, timing.

I could see a potential worst case scenario where a HECS forms but it's too far north and we get rain while we watch philly get crushed

[poolz1]

Beating a dead horse here a little but having this heading into Jan is as good as we can ask... AO forecasted to plummet.  Just having these two in our pocket is a beautiful thing..

[Maestrobjwa]

31 minutes ago, Ralph Wiggum said:

Yes. And if you believe the means it anchors in and meanders around the general NAO region. So hopefully as you said timing and luck can play a role when it ventures into the more favorable areas. GFS op is eye candy wrt HL blocking the entire run and even becomes more favorable farther out. But alas....op at range so salt grains and all that jazz.

Yeah don't wanna have to rely on luck and timing for anything...lol Let's hope it sets up in a better position!

Shoot...even when we can get the PV to split, then we gotta get it to split the right way? Always something, lol

[Chris78]

1 hour ago, poolz1 said:

Beating a dead horse here a little but having this heading into Jan is as good as we can ask... AO forecasted to plummet.  Just having these two in our pocket is a beautiful thing..

If I had to choose between a - AO or         - NAO I think id choose the AO. Luckily it looks like we may have both for a while.

[psuhoffman]

Para gfs is close on the 28. 

[ryanconway63]

DT is woofing hard at the 28/29 time frame

[psuhoffman]

One reason the GFS is cutting the wave around New Years is how it’s handling the Xmas-28 period.  Frankly all 3 globals have a different evolution but the other 2 end up with a massive 50/50 that sets up the Dec 30 on period. Euro bombs the Xmas system into that vortex then absorbs the Dec 30 wave to amplify it even more.  CMC is weaker with Xmas wave and develops a weaker vortex but then amplifies the dec 28 wave and they phase into a monster vortex. End result is the cmc and euro have a massive vortex to our northeast to suppress the flow. Gfs is weaker with both waves and so does not.
 

This is everything. to be clear “blocking” is a means to an end not the end. The actual effect of blocking that directly leads to our threats is the 50/50 feature.  Blocking is important because ridging around the NAO domain forces systems to track and get stuck in the 50/50 region. It’s that feature, though, that sets up the confluence and suppressed flow across the eastern US that we need.  If you look at all our big storms almost all had a NAO block. But the few exceptions had a well timed 50/50!  
 

As for the AO v NAO debate...it depends.  The AO being - encourages a more expensive jet into the Conus and cold. Depending on other factors it can also promote some 50/50 assistance but not as effective as the NAO.  If we have a cooperative PNA AO combo that works just fine. If there is a progressive pattern with open waves the AO can do just fine. Get the cold pressed south and let waves attack. Some of the 2014 systems worked that way.  We did have a -AO just not a -NAO at times that winter. Those kinds of waves can work without a blocked up pattern. But if you want a big dog HECS storm you want the NAO/50/50 combo. That combo can also bully the whole pattern and compensate for warts in other places.

so in conclusion Imo BIG snows are most correlated to the NAO/50/0 and just snow in general (be it 1” or 6”) is most correlated to the AO. 

[LP08]

Gfs is much more progressive with the Xmas cold front so far than the other globals. Hope it’s right.

[CAPE]

13 minutes ago, psuhoffman said:

One reason the GFS is cutting the wave around New Years is how it’s handling the Xmas-28 period.  Frankly all 3 globals have a different evolution but the other 2 end up with a massive 50/50 that sets up the Dec 30 on period. Euro bombs the Xmas system into that vortex then absorbs the Dec 30 wave to amplify it even more.  CMC is weaker with Xmas wave and develops a weaker vortex but then amplifies the dec 28 wave and they phase into a monster vortex. End result is the cmc and euro have a massive vortex to our northeast to suppress the flow. Gfs is weaker with both waves and so does not.
 

This is everything. to be clear “blocking” is a means to an end not the end. The actual effect of blocking that directly leads to our threats is the 50/50 feature.  Blocking is important because ridging around the NAO domain forces systems to track and get stuck in the 50/50 region. It’s that feature, though, that sets up the confluence and suppressed flow across the eastern US that we need.  If you look at all our big storms almost all had a NAO block. But the few exceptions had a well timed 50/50!  
 

As for the AO v NAO debate...it depends.  The AO being - encourages a more expensive jet into the Conus and cold. Depending on other factors it can also promote some 50/50 assistance but not as effective as the NAO.  If we have a cooperative PNA AO combo that works just fine. If there is a progressive pattern with open waves the AO can do just fine. Get the cold pressed south and let waves attack. Some of the 2014 systems worked that way.  We did have a -AO just not a -NAO at times that winter. Those kinds of waves can work without a blocked up pattern. But if you want a big dog HECS storm you want the NAO/50/50 combo. That combo can also bully the whole pattern and compensate for warts in other places.

so in conclusion Imo BIG snows are most correlated to the NAO/50/0 and just snow in general (be it 1” or 6”) is most correlated to the AO. 

Good post. I pointed this out with the last storm. The lack of a block and the resulting transient 50-50 low was one fundamental problem, esp for eastern areas. The confluence was on the move and displaced too far NE. 

eta: the -AO provides the mechanism to displace cold into the midlatitudes. Ofc we typically see a -NAO when the AO is persistently negative.

[JakkelWx]

Mood flakes on Christmas Day?

[jaydreb]

2 minutes ago, losetoa6 said:

Gfs snow on Xmas eve  then flurries on Xmas day.  Gotta love it . And really only a few hours above normal Thursday temp wise .Wednesday leading in has cad keeping us cool 

For who?  Looks like mostly rain to me.  

[poolz1]

GFS stronger with the x-mas wave once to the 50/50 region....and man, what a block.. 

[osfan24]

27 minutes ago, ryanconway63 said:

DT is woofing hard at the 28/29 time frame

I get things look promising but his thoughts are crazy. Best look since 1996? LOL. No models even have a snowstorm right now. This far out in 2016, almost every model was showing a storm and was locked in the rest of the way. 

[osfan24]

2 minutes ago, JakkelWx said:

Mood flakes on Christmas Day?

Fringed!

[jaydreb]

Just now, losetoa6 said:

No flooding rains lol. Pretty dry . Snow piles will be safe .

Took a step back on the snow from 6z but also less flooding rain.  

[jaydreb]

The 850 line is all the way down in NC but it’s raining up to Wisconsin.  Just can’t get any decent cold air?
 

 

[CAPE]

5 minutes ago, osfan24 said:

I get things look promising but his thoughts are crazy. Best look since 1996? LOL. No models even have a snowstorm right now. This far out in 2016, almost every model was showing a storm and was locked in the rest of the way. 

I assume he is only comparing the advertised h5 looks to past Ninas, but idk because I couldn't care less what he thinks lol.

[Weather Will]

Big story this week will be the single digit wind chills on Christmas.  Not a torch!!!  12Z WB GFS.

[frd]

11 minutes ago, poolz1 said:

GFS stronger with the x-mas wave once to the 50/50 region....and man, what a block.. 

Is the blocking more West based ?

Can you share an image?

[CAPE]

5 minutes ago, jaydreb said:

The 850 line is all the way down in NC but it’s raining up to Wisconsin.  Just can’t get any decent cold air?
 

 

 

Lots of potential with the general idea. GFS op continues to flash the west based -NAO.

[frd]

12 minutes ago, osfan24 said:

I get things look promising but his thoughts are crazy. Best look since 1996? LOL. No models even have a snowstorm right now. This far out in 2016, almost every model was showing a storm and was locked in the rest of the way. 

Even with blocking it  is fair to say that expectations should be tempered. But, wow, night and day versus last year at this time. 

[poolz1]

1 minute ago, frd said:

Is the blocking more West based ?

Can you share an image?

A bit more west based....

[NorthArlington101]

[CAPE]

Cutter at 240. Ji in 3..2..1..

[jaydreb]

1 minute ago, CAPE said:

Cutter at 240. Ji in 3..2..1..

Yeah.  I’ll channel my inner Ji and say that for all the potential, I don’t see any pretty colors over my house.  Just cutters and rain.  

[SnowGoose69]

6 minutes ago, CAPE said:

Cutter at 240. Ji in 3..2..1..

The Op GFS for some reason in -AO/NAO pattens has a tendency beyond 180 to love dumping trofs into the plains or west.  We saw this back near 12/1-12/5 and it never came close to verifying 

[ryanconway63]

60s on NYE per the GFS