December Mid/Long Range Discussion

[stormy]

Yesterday afternoon both Ji and I expressed suspicion of possible surprises early next week with an east coast storm.  This Watch still exists this morning.

The GFS,GEM and Euro all see a significant system affecting the SE/MA coastal region during this Sunday - Wednesday timeframe.

Heavy rain, snow and wind are all in the mix with run to run hiccups. The op GFS even gives my area 2 inches of snow on Tuesday night but the GEFS keeps any snow in the mts. to my northwest.

The latest ECM gives more impact to the area east of I-95 while the GFS suspects more inland impact.

 

[psuhoffman]

53 minutes ago, brooklynwx99 said:

OP runs have been keying in on a wave break into central Canada. this would be a much more interesting look if it retrogrades into NW Canada or Greenland like it has over the last few runs

I'm becoming increasingly confident this is entirely about the NAO.  First of all if you look at all the best analogs identified, 1958, 1966, 1973, 1987, 1992, 1995, 2010, 2016 the thing that differentiates them wrt snowfall was the NAO in those seasons.  58, 66, 87, 2010 were negative and snowy in the mid atlantic.  73, 92, 95 were positive and not.  2016 was the most ambiguous with some blocking in Jan/Feb but not as pronounced as the others and it ended up in between.  

 

Also look at days 4-8 on the EPS. 

The problem isn't the Pacific.  At range things get washed out and give the wrong impression.  Because pieces of the main vortex keep getting pulled off and diving into the CONUS, at range timing differences make that look like the vortex is actually extending into the west more than it is.  But look as it gets closer what it actually looks like.  

That low off the west coast is cut off, that's not a problem...the main Pac vortex is centered west of AK.  There is ridging into western Canada.  The issue there is the TPV over Baffin or IOW a raging positive NAO.  Because of that the PNA ridging just spreads out east across the CONUS.  If the NAO was negative that pacific look right there, day 4-8 not way out in time, would work just fine.  

This seems really simple to me...if we get the NAO to flip negative we will be fine, it will promote enough northerly flow into the northeast on top of us for these STJ systems to work...but if the NAO stays positive were screwed, the ridging out west off the PAC will just spread east and we end up with a full continent pacific onslaught. 

In a nino it really is all about the NAO.  There have really only been 2 exceptions in modern history...2003 and 1998.  1998 was so east based and so extreme due to the contrast between the super nino and a colder pac base state that it torched the CONUS despite a -NAO.  And 2003 was opposite, the Pacific trough was displaced west by the extreme modoki nature of that nino and so it worked out despite a less favorable NAO, although it wasnt as bad as what we have right now, not sure anything would save us with a strong vortex over Baffin, thats just nightmare stuff right there.  

 

[brooklynwx99]

3 minutes ago, psuhoffman said:

I'm becoming increasingly confident this is entirely about the NAO.  First of all if you look at all the best analogs identified, 1958, 1966, 1973, 1987, 1992, 1995, 2010, 2016 the thing that differentiates them wrt snowfall was the NAO in those seasons.  58, 66, 87, 2010 were negative and snowy in the mid atlantic.  73, 92, 95 were positive and not.  2016 was the most ambiguous with some blocking in Jan/Feb but not as pronounced as the others and it ended up in between.  

 

Also look at days 4-8 on the EPS. 

The problem isn't the Pacific.  At range things get washed out and give the wrong impression.  Because pieces of the main vortex keep getting pulled off and diving into the CONUS, at range timing differences make that look like the vortex is actually extending into the west more than it is.  But look as it gets closer what it actually looks like.  

That low off the west coast is cut off, that's not a problem...the main Pac vortex is centered west of AK.  There is ridging into western Canada.  The issue there is the TPV over Baffin or IOW a raging positive NAO.  Because of that the PNA ridging just spreads out east across the CONUS.  If the NAO was negative that pacific look right there, day 4-8 not way out in time, would work just fine.  

This seems really simple to me...if we get the NAO to flip negative we will be fine, it will promote enough northerly flow into the northeast on top of us for these STJ systems to work...but if the NAO stays positive were screwed, the ridging out west off the PAC will just spread east and we end up with a full continent pacific onslaught. 

In a nino it really is all about the NAO.  There have really only been 2 exceptions in modern history...2003 and 1998.  1998 was so east based and so extreme due to the contrast between the super nino and a colder pac base state that it torched the CONUS despite a -NAO.  And 2003 was opposite, the Pacific trough was displaced west by the extreme modoki nature of that nino and so it worked out despite a less favorable NAO, although it wasnt as bad as what we have right now, not sure anything would save us with a strong vortex over Baffin, thats just nightmare stuff right there.  

 

luckily, I don't think we'll really have to worry about the NAO. would be different if we had a death star SPV, but it's weak, and we have already had spells of blocking this fall and earlier in the month. i highly doubt the NAO domain remains like that for too long, let alone for the rest of the winter

[psuhoffman]

3 minutes ago, brooklynwx99 said:

luckily, I don't think we'll really have to worry about the NAO. would be different if we had a death star SPV, but it's weak, and we have already had spells of blocking this fall and earlier in the month. i highly doubt the NAO domain remains like that for too long, let alone for the rest of the winter

I tend to agree, weak SPV, descending -QBO, ascending solar... we shouldn't get a raging wall to wall +NAO... but that is the domain we need to be watching for changes more so than the pacific even imo.  The biggest reason for the loss of the better pattern projected for the end of Dec and early January on guidance was the degradation of the look on the Atlantic side more so than the Pacific.  

[psuhoffman]

That and this is a basin wide nino which isn't a bad thing...provided you have some NAO help.  But were not in a modoki like 2003 and 2015 where the pacific low will be displaced far enough west to work absent any NAO help.  

[Terpeast]

This recent -NAO late november, which model sniffed it out first? Gfs or euro?

just curious

[psuhoffman]

Just now, Terpeast said:

This recent -NAO late november, which model sniffed it out first? Gfs or euro?

just curious

One may have had it 12 hours sooner but both picked up on it about the same time since it showed up quick and not at super long leads.  

[brooklynwx99]

3 minutes ago, psuhoffman said:

I tend to agree, weak SPV, descending -QBO, ascending solar... we shouldn't get a raging wall to wall +NAO... but that is the domain we need to be watching for changes more so than the pacific even imo.  The biggest reason for the loss of the better pattern projected for the end of Dec and early January on guidance was the degradation of the look on the Atlantic side more so than the Pacific.  

the only issue is that with these kinds of winters with a generally susceptible -NAO state, they can just kind of pop up in the medium to semi-long range. that's what happened with the blocking spell early in the month. nothing really sniffed it out

if we are seeing a legit anomalous, long lasting -NAO brought on by Scandi ridging, it is probably very legit and we could get smoked. but that's speculation, of course. a SSW could help that occur, though

[psuhoffman]

Given the weak SPV it's possible for the NAO to shift quickly, all it would take is a good wave break to possibly set off a chain reaction.  One thing that does bother me a little... in the years that flipped in our favor there was pronounced Scandinavian ridging ahead of time in late December that proceeded the NAO going negative.  We don't have that this year...it looks like we will be relying on wave breaking to get it done and that's not how it went down in past Nino's that had an NAO flip Dec to Jan.  

[Maestrobjwa]

1 hour ago, psuhoffman said:

Given the weak SPV it's possible for the NAO to shift quickly, all it would take is a good wave break to possibly set off a chain reaction.  One thing that does bother me a little... in the years that flipped in our favor there was pronounced Scandinavian ridging ahead of time in late December that proceeded the NAO going negative.  We don't have that this year...it looks like we will be relying on wave breaking to get it done and that's not how it went down in past Nino's that had an NAO flip Dec to Jan.  

So...if the NAO were to end up sinking the ship this winter, would you attribute that to worsening climo, just bad luck, or worsening climo making said bad luck harder to overcome?

[ldub23]

 

Another  lt snow  event  possible?

[WinterWxLuvr]

Guaranteed cold

[stormtracker]

Even for a big rainstorm, I think this one is pretty interesting.  Drought denter at least.

[osfan24]

I know it's still early, but painful to see these missed opportunities. Looks like this one could have been Dec 2009 on steroids.

[psuhoffman]

42 minutes ago, Maestrobjwa said:

So...if the NAO were to end up sinking the ship this winter, would you attribute that to worsening climo, just bad luck, or worsening climo making said bad luck harder to overcome?

It's way too early for that, I still think its going to work out.  But...if it fails we would have to look at all the options, effects of last years eruption, there was a pretty significant solar flare recently, did tropical forcing end up in a state more conducive to a +NAO than the typical Nino, or random chaos... and of course it has seemed to be harder to get a -NAO recently, especially if you factor in we've been in an ascending solar phase where blocking SHOULD be more prevalent recently yet it wasn't.  But I am hopeful we never have to do that analysis.  

[NorthArlington101]

6 minutes ago, osfan24 said:

I know it's still early, but painful to see these missed opportunities. Looks like this one could have been Dec 2009 on steroids.

Well at least right now we aren't fretting the exact path of the MSLP. Looks to be more inland than would be good for a lot of the burbs.

Agree with others generally that I still don't think we have any clue what will happen after the big storm rolls through. Probably nothing, though you never know!

[brooklynwx99]

pretty wild wavebreaking showing up on the OP runs now... this is a trillion times better than what was advertised for this time period a few days ago

[midatlanticweather]

The GFS had a bit better of an evolution with the low. I mean, it is a good rainer and would be an amazing snow if it happened the right way and we had cold air. But the last few days it has looked soooo strange. 

More drought denting cold rain! Happy that it seems likely now. 

Wish things would get clearer in the long-range for more chances, but I think we are going to see some strange outcomes! THANK YOU to the knowledgeable posters for the details and nuances that can be good in the midst of a lot of bad looks. 

 

[brooklynwx99]

this is about as big of a positive change in the Pacific pattern as you can see, compared from a couple days ago. really want to see this idea gain some traction

[WxUSAF]

A trillion times is probably a few hundred billion too many, but GFS and GGEM both show wavebreaking on the Atlantic side that improves the NAO domain and brings some man highs toward us Xmas weekend. With the active storm track, there’s at least some intrigue if timing works out. So yeah, could be worse. Temps still don’t look like a blowtorch for our little corner of the world. Is the whole CONUS well AN? Totally. Will we have a AN December? Very likely, but still nowhere near 2015 for us.

[brooklynwx99]

5 minutes ago, WxUSAF said:

A trillion times is probably a few hundred billion too many, but GFS and GGEM both show wavebreaking on the Atlantic side that improves the NAO domain and brings some man highs toward us Xmas weekend. With the active storm track, there’s at least some intrigue if timing works out. So yeah, could be worse. Temps still don’t look like a blowtorch for our little corner of the world. Is the whole CONUS well AN? Totally. Will we have a AN December? Very likely, but still nowhere near 2015 for us.

the reason why I say a trillion is because it leads to a legit storm forming at the end of the run. this is way more fun than the blowtorch that was getting spit out a few days ago

[Rhino16]

15 minutes ago, brooklynwx99 said:

this is about as big of a positive change in the Pacific pattern as you can see, compared from a couple days ago. really want to see this idea gain some traction

So basically we want that jet to be further south?

[brooklynwx99]

wavebreaks are literal hell for LR ENS guidance so it makes sense that it might be getting sniffed out by OP runs. we shall see, but there is reason for optimism

[brooklynwx99]

Just now, Rhino16 said:

So basically we want that jet to be further south?

look over AK. goes from progressive flow to a massive block

[Heisy]

the reason why I say a trillion is because it leads to a legit storm forming at the end of the run. this is way more fun than the blowtorch that was getting spit out a few days ago

I don’t care if it’s 15 days out. Seeing some solid maps in fantasy range is always encouraging. It beats having them show garbage


.

[CAPE]

4 minutes ago, brooklynwx99 said:

wavebreaks are literal hell for LR ENS guidance so it makes sense that it might be getting sniffed out by OP runs. we shall see, but there is reason for optimism

Lets see what the ens mean looks like at the end of the run today. Hell of a look.

[NorthArlington101]

some quirky looks in there - worth keeping an eye on still.

[brooklynwx99]

8 minutes ago, CAPE said:

Lets see what the ens mean looks like at the end of the run today. Hell of a look.

if you roll that out, you get a KU and then the 50/50 leads to a -NAO block. total 180 from the garbage we were seeing only a few days ago

[psuhoffman]

23 minutes ago, WxUSAF said:

A trillion times is probably a few hundred billion too many, but GFS and GGEM both show wavebreaking on the Atlantic side that improves the NAO domain and brings some man highs toward us Xmas weekend. With the active storm track, there’s at least some intrigue if timing works out. So yeah, could be worse. Temps still don’t look like a blowtorch for our little corner of the world. Is the whole CONUS well AN? Totally. Will we have a AN December? Very likely, but still nowhere near 2015 for us.

IF, big if, things were to continue to follow a 2015/16 type pattern progression but slightly colder given the weaker enso, I would take that.  Our area just missed out on about 3 other big snow events in Jan-Mar because temps were just a few degrees too warm.  A pattern repeat of 2016 but slightly colder could be a big win.  

[psuhoffman]

12 minutes ago, CAPE said:

Lets see what the ens mean looks like at the end of the run today. Hell of a look.

Historically absent a NAO block the other feature that showed up next most frequently in our warning level snow events was a "west of Hudson Bay" ridge.  If we can get that ridging up top centered a little further west we would have a chance.  Of course ideally getting the vortex off Baffin Bay will help enormously but I really don't see that setting up shop permanently...the SPV is too weak, any TPV will be susceptible to destructive interference.