December Medium/Long Range Discussion

[aldie 22]

4 hours ago, Cobalt said:

0z Euro is encouraging it seems

Wrap it up

[aldie 22]

33 minutes ago, Weather Will said:

WB 6Z GEFS for Christmas 

Wrap this one up as well 

[CAPE]

33 minutes ago, WinterWxLuvr said:

Ever see a storm as whacky as the one on the gfs around 228? Watch that thing

loop d loop

It cant handle the block.

[aldie 22]

28 minutes ago, CAPE said:

loop d loop

It cant handle the block.

Mood flakes on Christmas then a big dog on the 30th would be a perfect way to end this miserable f'ing year

[Weather Will]

WB 6Z GEFS really still likes period between Christmas and early 2021...

[snowman19]

1 hour ago, frd said:

Highest heights are not in our favored area, looks like a East based Greenland block. We need that block to retro West into the Davis Straights. That could be one reason, but not the only one. 

That’s one issue, the other issue is the PAC side at the time

[frd]

14 minutes ago, Weather Will said:

WB 6Z GEFS really still likes period between Christmas and early 2021...

 

For once I can say that is starting to look better.  Models are still catching on to the blocking scenario and eventual outcomes at the lower latitudes. 

Also, I have not seen this blocking signature for some time, evident by the temp anomalies to our far NE via the Canadian 10 day mean. 

 

 

 

 

[frd]

Just now, snowman19 said:

That’s one issue, the other issue is the PAC side

When looking at the PNA domain it is possible things improve there, a short window with a more pronounced +PNA will help the storm threat window(s).  

I have not checked today, but yesterday it appeared the PNA was headed more positive and the NAO more negative. 

[snowman19]

Just now, frd said:

When looking at the PNA domain it is possible things improve there, a short window with a more pronounced +PNA will help the storm threat window(s).  

I have not checked today, but yesterday it appeared the PNA was headed more positive and the NAO more negative. 

It’s an EPO problem too, troughing over AK

[CAPE]

Although I did "promise" a white Xmas, the way its looking maybe the best chance (for some) is for the snowpack to survive the upcoming mild period, fog, and probably 1-2" of rain lol. 

Still a chance for a brief period of snow or snow showers behind the front, and maybe a coating. Flakes in the air is my bar.

[osfan24]

1 minute ago, CAPE said:

Although I did "promise" a white Xmas, the way its looking maybe the best chance (for some) is for the snowpack to survive the upcoming mild period, fog, and probably 1-2" of rain lol. 

Still a chance for a brief period of snow or snow showers behind the front, and maybe a coating. Flakes in the air is my bar.

That's going to be a tough road. We still have six days to go and it's going to warm up and we are going to get some sun this week and that's before we get all that rain and temps surge Thursday.

[CAPE]

5 minutes ago, osfan24 said:

That's going to be a tough road. We still have six days to go and it's going to warm up and we are going to get some sun this week and that's before we get all that rain and temps surge Thursday.

You got my point. 

[frd]

7 minutes ago, snowman19 said:

It’s an EPO problem too, troughing over AK

Well, psu made a great post on that. You can search for it, but we have our friend the - AO to help us. At least we are in the game after the 25 th.   

[Ralph Wiggum]

2 hours ago, frd said:

Highest heights are not in our favored area, looks like a East based Greenland block. We need that block to retro West into the Davis Straights. That could be one reason, but not the only one. 

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.

[Ralph Wiggum]

35 minutes ago, snowman19 said:

It’s an EPO problem too, troughing over AK

The trof is in the Aleutian chain. Thats not a horrible look with a split flow off the West coast.

[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..