December Medium/Long Range Discussion

[frd]

 

Looking forward to the next update, but this is rather impressive and starts in only a few days,  

 

 

[PivotPoint]

33 minutes ago, leesburg 04 said:

Let me guess, you always approach model and map reading with a "what could go wrong" eye?

Not at all. If you go back and read my posts starting 3+ weeks back I talked about how I thought that LR looked good for cyclical blocking regime and an Atlantic that is not fighting us. Haven’t had that combo in awhile.

I read maps at an amateur level anyways. So it probably doesn’t matter lol. But no, I just see what I see. And when it looks good I say so. When it doesn’t, I say so. It just happens that it looks not good more than it looks good. That’s our climo

[CAPE]

12 minutes ago, PivotPoint said:

Not at all. If you go back and read my posts starting 3+ weeks back I talked about how I thought that LR looked good for cyclical blocking regime and an Atlantic that is not fighting us. Haven’t had that combo in awhile.

I read maps at an amateur level anyways. So it probably doesn’t matter lol. But no, I just see what I see. And when it looks good I say so. When it doesn’t, I say so. It just happens that it looks not good more than it looks good. That’s our climo

Despite all the imperfectness, somehow things align in a way to produce snow a few times almost every winter.

[poolz1]

7 hours ago, psuhoffman said:

 

To me, the most surprising aspect of that mean is the lower heights off the west coast and extending into AK.  Would not have expected that to be the case.  Just south enough to give a little PNA love....doesnt have to be some monster PNA ridge out west.

[MillvilleWx]

3 minutes ago, poolz1 said:

To me, the most surprising aspect of that mean is the lower heights off the west coast and extending into AK.  Would not have expected that to be the case.  Just south enough to give a little PNA love....doesnt have to be some monster PNA ridge out west.

The ridge alignment is literally perfection with that setup too. You want those + height anomalies over ID/W MT for a reflection of SLP track along and off the eastern seaboard. The premise of 100-200 miles in exact placement of succinct ridge/trough patterns is a marvel to think about on a hemispheric scale. The big ones need that star alignment, and the fact it happens as often as it does is pretty outstanding. I love weather  

[dallen7908]

7 hours ago, psuhoffman said:

@Ji Just sayin maybe we should let this play out. The blocking is just establishing itself next week. With each wave break it retrogrades more into a canonical blocking regime.  Both the TPV and SPV look to get obliterated soon.  We typically score after the blocking peaks not before. 

I wonder when this will be .. The AO and NAO look stable and negative for the last few days of 2020 and the first week of 2021. 

The DC-proper snow means from the GEFS and EPS for the next 10-15 days are less than 1" (below the 2" amount that is typical this time of year)

The good news is the large-scale pattern is not close-the-window-shades bad.  Its been a decade since we've had anything in the mid-range to track in late December - still a chance this year. 

[psuhoffman]

2 hours ago, PivotPoint said:

Unfortunately, the blue is all types of wrong out west lol. It’s always 10 days away @psuhoffman lol. Crazy block though 

Again, one frame at 384 hours. And flow looks pretty flat coming off the PAC. I’m beginning to worry that we won’t score with a bad PAC and troughing south of AK. Seems like that a recipe for warm wet, cold dry sequence over and over again. Can’t not expect it though. That’s kinda La Niña for you

Is it...the blues out west look pretty close to this...

Remember blocking changes what works out west.   Without blocking that wouldn’t work.  With blocking you want that trough off the west coast to kick everything along and promote enough ridging over the CONUS to prevent suppression. If we had what we think of as a ideal pac with great blocking everything would get squashed. That’s a cold dry look.  On the plot you posted I don’t see a disaster. The WPO vortex backed off enough to allow some epo ridging. The system south of AK is far enough south not to flood pac puke across.  It’s part of the flow not detached. I’d like a little more pna but it’s not bad.  If we have blocking.

1 hour ago, poolz1 said:

To me, the most surprising aspect of that mean is the lower heights off the west coast and extending into AK.  Would not have expected that to be the case.  Just south enough to give a little PNA love....doesnt have to be some monster PNA ridge out west.

Look at my response above. I think some are looking for the “ideal” pac but what is ideal changes based on other factors. It’s a balance. What’s on one side changes what we want on the other. A full latitude EPO/PNA ridge at the same time as a -AO/NAO is really rare. First of all you almost need the tpv to either drop into the US or completely vacate our side to get that. And when we have gotten that mid winter it’s tended to be a cold dry look. Think Jan 1977. 

52 minutes ago, dallen7908 said:

I wonder when this will be .. The AO and NAO look stable and negative for the last few days of 2020 and the first week of 2021. 

The DC-proper snow means from the GEFS and EPS for the next 10-15 days are less than 1" (below the 2" amount that is typical this time of year)

The good news is the large-scale pattern is not close-the-window-shades bad.  Its been a decade since we've had anything in the mid-range to track in late December - still a chance this year. 

Imo the snow mean hasn’t responded yet because after the New Years storm it’s dry. And that’s to be expected with that blocking look. The New Years period is the HA storm on the front end as the blocking goes up. The wave break from those 2 systems help get the block into our canonical location. Once there though waves will likely slow down over the CONUS...blocking. We would then need the blocking to start to relax some. Or...the Feb 2010 option when a really strong stj wave attacked the blocking aided by a trough off the west to promote enough ridging (and the wave was strong enough not to shear out) to get that moisture to attack the block.  But waves will likely be less frequent after the blocking establishment 

[psuhoffman]

4 hours ago, CAPE said:

Hopefully this doesn't become a can kicking exercise in the LR. This is where we want the block, and we hope for some Pacific cooperation. This is a good look right here.

EPS has an impressive west based -NAO as well, but maybe a bit less favorable look out west.

 

EPS look out west is more problematic.  Not a total deal breaker...we have had some good snowstorms in that look but its not as common as if that trough stays centered off the west coast a bit more allowing just a little bit of PNA ridge into the southwest.  Perfect blocking can erase a lot of issues in other areas though.  I wonder if we saw this....would we pick apart the less then ideal pacific?

[psuhoffman]

Keep in mind also...when you look at the ensemble means at day 10-15 because of timing differences on waves details get washed out.  The blue in the west is not a big huge trough...its from pacific waves crashing in every couple days.  We need those waves...hopefully one of them ends up our snowstorm.   There would be short periods with some PNA ridging in between imo...but its getting washed out by the lower heights of the waves crashing and the timing differences between members.  

[howrdcounty snow]

1 minute ago, psuhoffman said:

Keep in mind also...when you look at the ensemble means at day 10-15 because of timing differences on waves details get washed out.  The blue in the west is not a big huge trough...its from pacific waves crashing in every couple days.  We need those waves...hopefully one of them ends up our snowstorm.   There would be short periods with some PNA ridging in between imo...but its getting washed out by the lower heights of the waves crashing and the timing differences between members.  

sir would you define the waves crashing into west coast as the southern jet??

[CAPE]

10 minutes ago, psuhoffman said:

EPS look out west is more problematic.  Not a total deal breaker...we have had some good snowstorms in that look but its not as common as if that trough stays centered off the west coast a bit more allowing just a little bit of PNA ridge into the southwest.  Perfect blocking can erase a lot of issues in other areas though.  I wonder if we saw this....would we pick apart the less then ideal pacific?

Nina vs Nino background state is one difference. Pac is inherently more hostile to our snow chances during a typical Nina, although this may be less of a factor now and moving forward.

[psuhoffman]

5 minutes ago, howrdcounty snow said:

sir would you define the waves crashing into west coast as the southern jet??

I saw one pure STJ wave. Others were polar jet in origin.  But that’s ok when they eject into the plains they can pick up stj moisture. 

[psuhoffman]

4 minutes ago, CAPE said:

Nina vs Nino background state is one difference. Pac is inherently more hostile to our snow chances during a typical Nina, although this may be less of a factor now and moving forward.

True but I haven’t seen much of a typical Nina response yet. 

[Eskimo Joe]

 

[howrdcounty snow]

1 minute ago, Eskimo Joe said:

 

isn't that the cold air were hoping for as critical ingredient for snow, among others?

[MillvilleWx]

I wanted to post where there will be higher viewer traffic in the sub-forum. This is a really awesome site created by a few researchers and developers for NWS.

.

[aldie 22]

HM was wondering when was the last January that had above average snow in the NE, MA, MW and the UK at the same time. I'm calling January a blockbuster now...10" for everybody!!!

[nj2va]

NYE/New Years day looks quite similar to Christmas Eve/Day on the 12z GFS.  Huge cutter, driving rainstorm on NYE, front pushes through and gets cold on New Years Day.  

[howrdcounty snow]

1 minute ago, nj2va said:

NYE/New Years day looks quite similar to Christmas Eve/Day on the 12z GFS.  Huge cutter, driving rainstorm on NYE, front pushes through and gets cold on New Years Day.  

how can that happen with the huge block??

[EastCoast NPZ]

Just now, nj2va said:

NYE/New Years day looks quite similar to Christmas Eve/Day on the 12z GFS.  Huge cutter, driving rainstorm on NYE, front pushes through and gets cold on New Years Day.  

Awesome.  More  warm /wet followed by wind/dry/cold...in that order of intensity. 

[WxUSAF]

3 minutes ago, nj2va said:

NYE/New Years day looks quite similar to Christmas Eve/Day on the 12z GFS.  Huge cutter, driving rainstorm on NYE, front pushes through and gets cold on New Years Day.  

Some hints of a CAD situation though...  If we could get some energy to run out ahead or get some overrunning ahead of that warm front, that could be a way to get some frozen precip.  

1 minute ago, howrdcounty snow said:

how can that happen with the huge block??

Crappy Pac pattern.  

[nw baltimore wx]

1 minute ago, howrdcounty snow said:

how can that happen with the huge block??

I think @CAPE said it well when he said be patient and let the pattern develop. Things may look different and hopefully better early next week.

[howrdcounty snow]

1 minute ago, nw baltimore wx said:

I think @CAPE said it well when he said be patient and let the pattern develop. Things may look different and hopefully better early next week.

tyvm 

[nj2va]

7 minutes ago, WxUSAF said:

Some hints of a CAD situation though...  If we could get some energy to run out ahead or get some overrunning ahead of that warm front, that could be a way to get some frozen precip.  

Crappy Pac pattern.  

Yeah, I was being a bit cheeky with my post since its sort of lol-worthy seeing it again exactly a week later.  If we could either break out some of that energy so it’s not so robust out west (could keep it weak enough so its not a giant cutter) or get a piece of it to run ahead like you said, we could score some frozen especially with that 1039 H over Ontario.  That H seems new this run unless I wasn’t paying close enough attention - and the post Christmas cutter is acting as a pseudo 50/50 for that H to slow down.  Bears watching for sure.

[osfan24]

12 minutes ago, WxUSAF said:

Some hints of a CAD situation though...  If we could get some energy to run out ahead or get some overrunning ahead of that warm front, that could be a way to get some frozen precip.  

Crappy Pac pattern.  

Best pattern since 1996!

[psuhoffman]

5 minutes ago, WxUSAF said:

Some hints of a CAD situation though...  If we could get some energy to run out ahead or get some overrunning ahead of that warm front, that could be a way to get some frozen precip.  

Crappy Pac pattern.  

The pac isnt good so we need the blocking to be perfect.  I think were jumping the gun also...saw the block go up and jumped on the first waves coming across.  But the block is initially just an extension of the WAR but with each wave break it retrogrades more and more into a classic NAO block.  The problem is at 150 as the trough is amplifying out west the wave break from the storm after xmas is just starting to get the ridging to retro further west...but there is already ridging in the east at this point.  And the blocking is frankly still SE of ideal ATT.  It's the wave break from the new years system that retrogrades the block into the perfect position that could then be expected to offset the pacific.  A WAR that extends into the eastern NAO domain isn't going to cut it.  We need a west based rex block to offset the pac.  Luckily the guidance shows that...but not until after the new years system.  I do think there is a chance that trends colder into some kind of mix event though if we can get the energy to eject in pieces.  

[jaydreb]

3 minutes ago, psuhoffman said:

The pac isnt good so we need the blocking to be perfect.  I think were jumping the gun also...saw the block go up and jumped on the first waves coming across.  But the block is initially just an extension of the WAR but with each wave break it retrogrades more and more into a classic NAO block.  The problem is at 150 as the trough is amplifying out west the wave break from the storm after xmas is just starting to get the ridging to retro further west...but there is already ridging in the east at this point.  And the blocking is frankly still SE of ideal ATT.  It's the wave break from the new years system that retrogrades the block into the perfect position that could then be expected to offset the pacific.  A WAR that extends into the eastern NAO domain isn't going to cut it.  We need a west based rex block to offset the pac.  Luckily the guidance shows that...but not until after the new years system.  I do think there is a chance that trends colder into some kind of mix event though if we can get the energy to eject in pieces.  

Thanks.  It’s amazing how many things need to align for us to snow even in late December-early January.  

[JakkelWx]

The block's going to retrograde west folks and we'll get our good pacific, lol. Relax. The good stuff won't come until the 1st week of January or after.

[Climate175]

There is digital snow in some places N and W this run long range lol.

[psuhoffman]

To illustrate 

the blocking is just starting to get into a position to do any good here...but look at the ridge already in the northeast. It’s not in time to save the New Years threat if that energy comes across in one piece and amplifies to our west. but look at a few days later...

This look should offset the pac. Actually in this look I want the pac shooting energy in otherwise that’s a dry look likely. It would be very difficult to get a cutter in this look once the blocking gets established in the western NAO domain. Would be hard to get enough ridging in that flow.