December Medium/Long Range Discussion

[WxUSAF]

^thanks @frd. Maybe that’s the sort of linkage that could keep us chilly if the MJO gets to phase 6 in ~15 days. 

[yoda]

43 minutes ago, Allsnow said:

Drool worthy look to start December 

 

[frd]

A lot going for early December , especially towards the second week of December. Including a possible  PV displacement, PV elongation,  and the effect of a Siberian warming and the 7 day lag to NA, especially in the East. The displacement event if it were to occur could have implications for later in the month, in a way echoing Matt's thoughts from the post above.   

 

 

 

[Maestrobjwa]

2 hours ago, WxUSAF said:

Ha. 
 

We’ve got a nice pattern the first 10-14 days of December and already have a window or two picked out. That’s really good for December! Especially in a mod/strong Nina! 

So my question is...what do things have to look like to not make the snow miss? Lol Sounds like a dumb question, but what I'm saying is...is there anyway to tell in the LR if things look good enough that storms won't miss just northeast of here ala the bomb cyclone or boxing day 2010. When I think of ninas, I assume north or late developing is always an additional battle to fight...To prevent such, do we need even more blocking up top than we would during neutral/nino?

[CAPE]

28 minutes ago, Maestrobjwa said:

So my question is...what do things have to look like to not make the snow miss? Lol Sounds like a dumb question, but what I'm saying is...is there anyway to tell in the LR if things look good enough that storms won't miss just northeast of here ala the bomb cyclone or boxing day 2010. When I think of ninas, I assume north or late developing is always an additional battle to fight...To prevent such, do we need even more blocking up top than we would during neutral/nino?

It is impossible to resolve the minor details associated with how a specific storm will evolve and progress at this range. All we can do is identify the major components of the pattern and determine that the potential is there. It can be the most favorable pattern ever seen on paper and still produce no snow. The advertised h5 pattern is much more of a Nino look btw.

[Eskimo Joe]

00z op EURO appears to have a couple hours of back end snow west of US 15 on Dec 5th.

[WxUSAF]

56 minutes ago, Maestrobjwa said:

So my question is...what do things have to look like to not make the snow miss? Lol Sounds like a dumb question, but what I'm saying is...is there anyway to tell in the LR if things look good enough that storms won't miss just northeast of here ala the bomb cyclone or boxing day 2010. When I think of ninas, I assume north or late developing is always an additional battle to fight...To prevent such, do we need even more blocking up top than we would during neutral/nino?

The advertised pattern clearly supports coastal storms or storms passing south of us in general. Doesn’t mean every storm will do that, but pattern is supportive of that. Question is going to be whether the air mass ahead of any individual storm is conducive to snow. You can see this with the Dec 4-5 window. We need the Nov 30/Dec 1 storm to give us a fresh cold air mass and then have the next storm move into it at the right time before it rots. We don’t need a *ton* of help for a suitable airmass in early December, but we need some. A climo air mass doesn’t cut it usually. 

[40westwx]

8 hours ago, yoda said:

00z EURO was better... but still too late and inland for most of us -- re Dec 5 threat.  At 216 SLP is down by the AL/GA/FL border trifecta at 1003mb... at 240 its 981mb SLP is right near PHL.  Makes me think EPS should have a few snowy solutions tonight

Did that Low give us any snow?  It looked promising on TTs

[40westwx]

I am going to post this here instead of digital snow.. I know it is the 240 hour euro .. but it is a good pattern.. and we need a distraction..

 

 

[40westwx]

and here is the low pressure...

 

 

[WxUSAF]

Overnight euro and new parallel gfs were pretty similar. Paste bomb for mountains and far western burbs. 
 

So far I don’t like the 12z gfs at all. Although that 500mb low pass for the Dec 1 storm looks fairly amazing in isolation. 

[WxUSAF]

14 minutes ago, WxUSAF said:

Overnight euro and new parallel gfs were pretty similar. Paste bomb for mountains and far western burbs. 
 

So far I don’t like the 12z gfs at all. Although that 500mb low pass for the Dec 1 storm looks fairly amazing in isolation. 

Ooohh...12z ggem is so close to the perfect scenario. Just brings the second storm a bit too soon so it’s a cold rain, but the track is near perfect. 

[BristowWx]

1 minute ago, WxUSAF said:

Ooohh...12z ggem is so close to the perfect scenario. Just brings the second storm a bit too soon so it’s a cold rain, but the track is near perfect. 

maybe first flakes?  that would be a huge win for my crap location.  RA/SN mix even

[WxUSAF]

16 minutes ago, BristowWx said:

maybe first flakes?  that would be a huge win for my crap location.  RA/SN mix even

Verbatim probably not outside the highlands. But just like a 12-24 hr delay probably is cash money for I-95.

[frd]

Damn the AO forecast looks good.  Hope it happens !

 

[BTRWx's Thanks Giving]

Just a random comment, the new para gfs looks very similar to the euro throughout the run!

[BristowWx]

2 hours ago, WxUSAF said:

Verbatim probably not outside the highlands. But just like a 12-24 hr delay probably is cash money for I-95.

Que up the it’s happening gif

[NorthArlington101]

A Hecs on the Euro for Ohio and Indiana Monday.  2 foot amounts showing up.  

EPS has consistently been further East. Will be interesting to see what wins.

 

[Maestrobjwa]

Just now, NorthArlington101 said:

EPS has consistently been further East. Will be interesting to see what wins.

Could ya say that in ninas it's better to assume east? Lol

[poolz1]

End of the GEFS run looks mighty tasty..  Hoping to see that look move forward in time....Lets get some decent cold into the pattern so we can have our own digital historic storms.

[Maestrobjwa]

46 minutes ago, poolz1 said:

End of the GEFS run looks mighty tasty..  Hoping to see that look move forward in time....Lets get some decent cold into the pattern so we can have our own digital historic storms.

Is the end of a run ever really worth looking at? I'm wondering if it's better to wait for 10 days or like 240 hrs...I mean on hour 384...what can we reasonably glean from that? Possible trends?

[cbmclean]

Just now, Maestrobjwa said:

Is the end of a run ever really worth looking at? I'm wondering if it's better to wait for 10 days or like 240 hrs...I mean on hour 384...what can we reasonably gleam from that? Possible trends?

I'd rather it look good in the ultra-long range than bad.  I look at it this way: given the known model biases towards cold in the long range, if the long range looks good, it might turn out good, it might turn out bad, it might turn out average.  If the long range looks warm, that is indicative of a strong warm signal.  Of course I'm just referring to consistent runs that move forward in time.  Plenty of times the ultra-long ranges just flip back and forth randomly; just NWP noise.

[poolz1]

13 minutes ago, Maestrobjwa said:

Is the end of a run ever really worth looking at? I'm wondering if it's better to wait for 10 days or like 240 hrs...I mean on hour 384...what can we reasonably gleam from that? Possible trends?

Obviously, every hour into the future a model runs the less skill it has.  15 day ens runs are good for general ideas, imo.  Just like snow means, and members...useful if used correctly.  No doubt though, beyond day 10 is the general ballpark range...which is why I said I'd like to see it move forward in time.... 

[BristowWx]

I like LWX choice of words in the AFD...wintry precip chances non-zero...so you are saying there’s a chance

[Eskimo Joe]

Saving this one for posterity.

 

[CAPE]

Some snippets from a very detailed AFD from Mount Holly this afternoon-

 As ridging builds over the Pacific Northwest and southwest Canada, a strong +PNA will develop. This begins over the weekend, then strengthens early to mid next week as an even stronger ridge builds in over the Northwest. This will force a downstream trough over the eastern and southeastern US beginning late in the weekend and likely continuing through most or all of next week, driving colder air into the southern US. Notably, this pattern is very counter to what would normally be expected in a moderate to strong La Nina. But a good reminder that other aspects of intraseasonal forcing can sometimes overcome the dominant global pattern driver. It is also usually an active, stormy pattern for the East Coast.

Sunday night-Wednesday... As mentioned above, active weather is likely for this period. It will be a highly complex evolution as the new pattern takes shape. We will be watching two systems which are likely to begin interacting late in the weekend. One is a Canadian clipper low dropping towards the northern Great Lakes. The other is a robust southern stream wave propagating out of the desert Southwest, supported by an anomalously strong subtropical jet. Guidance has given strong indications for days that these systems are likely to phase over the East. However, as is usually the case, this interaction is likely to be complex, and while the general signal between models is fairly consistent, there are significant differences in details and timing.

By the middle to end of next week, additional unsettled weather is possible as trailing shortwave disturbances rotate into the broader longwave trough in the East. With colder air in place, wintry outcomes may be more favored with time, but given the uncertainty associated with the early week system, changes are likely.

[psuhoffman]

2 hours ago, losetoa6 said:

Eps looks real nice as well to me day 8 through the end . Should be lotssss of tracking in our future .

This look

With that SW-NE ridge axis across Canada centered just north of Hudson Bay is actually a really good one that has lead to many moderate snow events in our region historically.  I’m not getting into the “but will it happen debate”. But I am of the mine it’s better to look good than bad. Last year proved having the long range look awful all winter isn’t a good thing.  Additionally seeing the pattern look nothing like a typical Nina (and that feature is not way out in fantasy land) is a positive development. The pattern analogs are littered with nino years right now. And even Nov 1995 in there. Sometimes we get lucky and the atmosphere just does something crazy. Not saying I feel optimistic yet...but there are positive signs. 

[Heisy]

5 minutes ago, psuhoffman said:

This look

With that SW-NE ridge axis across Canada centered just north of Hudson Bay is actually a really good one that has lead to many moderate snow events in our region historically.  I’m not getting into the “but will it happen debate”. But I am of the mine it’s better to look good than bad. Last year proved having the long range look awful all winter isn’t a good thing.  Additionally seeing the pattern look nothing like a typical Nina (and that feature is not way out in fantasy land) is a positive development. The pattern analogs are littered with nino years right now. And even Nov 1995 in there. Sometimes we get lucky and the atmosphere just does something crazy. Not saying I feel optimistic yet...but there are positive signs. 

Good post, but one thing...I recall the opposite last year. The long range always showed shades of a great pattern, but would end up changing over and over...hopefully the look holds this time

[SnowLover22]

4 minutes ago, psuhoffman said:

This look

With that SW-NE ridge axis across Canada centered just north of Hudson Bay is actually a really good one that has lead to many moderate snow events in our region historically.  I’m not getting into the “but will it happen debate”. But I am of the mine it’s better to look good than bad. Last year proved having the long range look awful all winter isn’t a good thing.  Additionally seeing the pattern look nothing like a typical Nina (and that feature is not way out in fantasy land) is a positive development. The pattern analogs are littered with nino years right now. And even Nov 1995 in there. Sometimes we get lucky and the atmosphere just does something crazy. Not saying I feel optimistic yet...but there are positive signs. 

are there specific analogs to it being a Nina but the atmosphere looking nothing like that. If so how did we do those years? So I guess the question is are there analogs to us doing well in Nina years because the atmosphere did not respond to what was expected.

[raindancewx]

December never looked particularly terrible to be me for the East. Still think it's warm overall, but it's warm + snowy more than warm and boring.

I've been looking hard at 1959 lately - that's a near La Nina with a very warm NE Pacific. There is definitely resemblance to early December 1959 in the current depictions by CPC. I'd say 12/1-12/10 overall looks a lot like 1988 too as currently depicted - both of those years still finish warm in the East but they're much better patterns for snow than a normal warm month would see. I think there are some SE snowstorms or ice storms this month down to I-40, but we'll see.