December Medium/Long Range Discussion

[Ji]

Anything noteworthy here?

[Ralph Wiggum]

Just now, Ji said:

Anything noteworthy here?

Looks a little like tomorrow's setup.

[psuhoffman]

2 minutes ago, Ji said:

Anything noteworthy here?

That’s in the general window we have before the AK vortex invades pac puke across. It’s not a great pattern but it’s in that zone where I wouldn’t be shocked if absolutely nothing comes of it or if we luck into something between the 12-18th.  
 

longer range the GEFS improved slightly. Retrograde the ridge on the Atlantic side some and that AK trough could get forced out. Either drop in under or retrograde west. Either works.  It’s an ugly look for Xmas but could lead somewhere better after that. Last year we were facing an evolution where the only light at the end I saw was an oncoming train.  

[MJO812]

7 minutes ago, Ji said:

Anything noteworthy here?

Alot of cold air but  it is risky anytime we have to rely on a storm along a front. 

[CAPE]

8 minutes ago, Ji said:

Anything noteworthy here?

It's a way offshore low developing on a cold front following a cutter. Our typical cold chasing rain deal.

[DTWXRISK]

IN MAJOR   DEVELOPMENT    the  ecmwf    enso model shows   DRAMATIC  WEAKENING  of the Moderate  La Nina.

It is hard to understate   how  BIG  this is...or   COULD be... 

 a   rapidly  weakening   La Nina...   in essence a   WEAK  La Nina combined with  SSW   EVENT

[DTWXRISK]

6 minutes ago, MJO812 said:

Alot of cold air but  it is risky anytime we have to rely on a storm along a front. 

  the    DEC 14   event I have been talking about  since last week   and in the    3 week newsletter   but I am not  sure  which short wave   might be " the chance "/
 or the   s/w   behind   DEC   16

 

[Heisy]

2 minutes ago, CAPE said:

It's a way offshore low developing on a cold front following a cutter. Our typical cold chasing rain deal.

Idk I mean verbatim,  yeah, but probably the only legit shot for a while... not impossible

[CAPE]

Just now, Wentzadelphia said:

Idk I mean verbatim,  yeah, but probably the only legit shot for a while... not impossible

I didn't say there wasn't any potential for that window. Was just answering his question about the actual depiction for that run.

[MJO812]

11 minutes ago, DTWXRISK said:

  the    DEC 14   event I have been talking about  since last week   and in the    3 week newsletter   but I am not  sure  which short wave   might be " the chance "/
 or the   s/w   behind   DEC   16

 

Glad to have you back. Looking forward to your posts. 

[CAPE]

Pretty decent warming upstairs advertised towards day 15 on the GEFS.

 

[frd]

I had not seen this.  I imagine one's  perception can alter what is really  seen here.

For the record I do not endorse the Euro. It has had various issues with its forecasts and various indices. 

Eric Fisher

 

@ericfisher

 

Some new Euro seasonal data off the presses. No big changes...still a strong La Nina look heading toward January and February

 

 

 

8:42 AM · Dec 6, 2020

[CAPE]

^Seasonals, meh. Almost exactly what the latest CFS looks like. Boilerplate Nina stuff.

[psuhoffman]

23 minutes ago, DTWXRISK said:

IN MAJOR   DEVELOPMENT    the  ecmwf    enso model shows   DRAMATIC  WEAKENING  of the Moderate  La Nina.

It is hard to understate   how  BIG  this is...or   COULD be... 

 a   rapidly  weakening   La Nina...   in essence a   WEAK  La Nina combined with  SSW   EVENT

It’s good news...but it doesn’t get back to weak Nina status until around Feb and there is typically a lag in atmospheric response so I’m not totally sure it will save us from a generally hostile pacific pattern during the “meat” of winter. I am optimistic at signs (including the SSW) that we might get more help up top and on the Atlantic side that could offset a less ideal pac pattern at times. Last year EVERYTHING was wrong.  And not saying the weakening Nina isn’t a good though. Every bit helps. 

[psuhoffman]

3 minutes ago, CAPE said:

^Seasonals, meh. Almost exactly what the latest CFS looks like. Boilerplate Nina stuff.

Ugly. January I could envision some brief periods of opportunity within that mean...but not many any Feb looks like last winters pattern. 

[CAPE]

2 minutes ago, psuhoffman said:

Ugly. January I could envision some brief periods of opportunity within that mean...but not many any Feb looks like last winters pattern. 

Yeah there would be some chances embedded in there, but a lot would have to go right. Luckily those models are notoriously low skill, so there is that.

[DTWXRISK]

FWIW I  consider  March to be  part of winter

if you take a look at recent Trends over the past 20 or 25 years you will have noticed that the month of December has really become an extension of November for the eastern half of the  CONUS.   By that we mean that for the most part they  have not  been a  lot of significant cold air outbreaks or big snow storms especially  before Christmas.  On the other hand over the past 20-25 years the month of March has seen very little early spring weather in the eastern half of the country.  There have been quite a few number of significant snow storms ice storms and below normal temperatures

[psuhoffman]

@DTWXRISK true and the weakening Nina definitely could have a significant impact by March! 

[CAPE]

Really good look here in the NA on the 12z EPS. Too bad its wasted in (partially) mitigating a craptastic EPAC. Good example of how it can keep our region from being super warm though. As depicted we would probably be around average for temps, but pretty bleak prospects for frozen.

[DTWXRISK]

CAPE  ..  the    Big Alaskan  Upper  Trough / Low is  in part   associated with  Mod / strong  La Nina

 in 2nd half of the winter   as  La Nina weakens   that feature will go  bub bye ...   and IF .IF...   Atlantic side  holds  
  we may be in   business

[CAPE]

1 minute ago, DTWXRISK said:

CAPE  ..  the    Big Alaskan  Upper  Trough / Low is  in part   associated with  Mod / strong  La Nina

 in 2nd half of the winter   as  La Nina weakens   that feature will go  bub bye ...   and IF .IF...   Atlantic side  holds  
  we may be in   business

Yeah I get that. Hopefully the Nina does in fact weaken towards mid/late winter. I am skeptical of any sustained AO/NAO help, because it has been so rare in winter lately, and unfavorable QBO, etc. Maybe our best shot would be a -EPO period if the Nina eases some. Ofc a SWE can also shift things in the high latitude troposphere.

[psuhoffman]

@DTWXRISK @CAPE

agree plus if we can get repeated periods of Atlantic blocking we could also luck into a window when the pacific pattern relaxes just enough.  NAO will exert more influence as we head later in the season imo. 
ETA: let me be clear I’m not arguing we have a great winter incoming. Just things don’t look as bleak as last year ATT. 

[CAPE]

1 minute ago, losetoa6 said:

Near normal to just below normal temps makes it that much easier to get something to break our way vs a torch pattern .Watching the whole progression days 8,10,12 look to be the rough potential chances.  Starting with the left over large piece of energy from the late week cutter diving under us then it moving into the 50/50 position setting up another shot around day 10 ish and again day 12ish + . 

Well yeah that is a projected mean, but it certainly would not be a shoutout look for the latter third of December, esp up your way,

[leo2000]

2 hours ago, psuhoffman said:

The EPS still shows a brief window around Dec 16-18 before the pac puke arrives if something can amplify before the cutter vacates the 50/50 region.  After that looks ugly. Silver lining is the Atlantic side stays ok. Unlike last year there are hints, including signs of a SSW, that the NAM might not be a complete lost cause this year. The pac looks a mess. I kind of assumed that was coming. But last year the Atlantic side was hostile too. That’s a no hope situation. If we get some Atlantic side help this year we should get some opportunities. It will still be a struggle and a fight. Nothing will come easy. But it’s not hopeless like last year. 

Pacific not completely hostile we have a -WPO. 

[PivotPoint]

3 hours ago, psuhoffman said:

The EPS still shows a brief window around Dec 16-18 before the pac puke arrives if something can amplify before the cutter vacates the 50/50 region.  After that looks ugly. Silver lining is the Atlantic side stays ok. Unlike last year there are hints, including signs of a SSW, that the NAM might not be a complete lost cause this year. The pac looks a mess. I kind of assumed that was coming. But last year the Atlantic side was hostile too. That’s a no hope situation. If we get some Atlantic side help this year we should get some opportunities. It will still be a struggle and a fight. Nothing will come easy. But it’s not hopeless like last year. 

That’s the key and how we get lucky now and again. Spacing is close enough where a cutter turns 50/50 and allows the a s/w on it heels to drag the boundary far enough east that it locks some cold on tap. 
 

Atlantic will need to ply nice so it still doesn’t run west of us, but not such a pushover that It doesn’t develop and slides OTS.

Atlantic can’t be any worst than last year. It was horrendous.

1 hour ago, psuhoffman said:

It’s good news...but it doesn’t get back to weak Nina status until around Feb and there is typically a lag in atmospheric response so I’m not totally sure it will save us from a generally hostile pacific pattern during the “meat” of winter. I am optimistic at signs (including the SSW) that we might get more help up top and on the Atlantic side that could offset a less ideal pac pattern at times. Last year EVERYTHING was wrong.  And not saying the weakening Nina isn’t a good though. Every bit helps. 

I tend to agree with the lag on these big seasonal drivers. But DT is right on the mid Atlantic goal posts — it’s really not till very end of Dec through mid March. WW has pushed itself closer to start of spring over the last 20 years in NOVA and I don’t know how to explain why , but anecdotally, I feel like it has.

1 hour ago, DTWXRISK said:

FWIW I  consider  March to be  part of winter

if you take a look at recent Trends over the past 20 or 25 years you will have noticed that the month of December has really become an extension of November for the eastern half of the  CONUS.   By that we mean that for the most part they  have not  been a  lot of significant cold air outbreaks or big snow storms especially  before Christmas.  On the other hand over the past 20-25 years the month of March has seen very little early spring weather in the eastern half of the country.  There have been quite a few number of significant snow storms ice storms and below normal temperatures

Totally agree with this

1 hour ago, DTWXRISK said:

CAPE  ..  the    Big Alaskan  Upper  Trough / Low is  in part   associated with  Mod / strong  La Nina

 in 2nd half of the winter   as  La Nina weakens   that feature will go  bub bye ...   and IF .IF...   Atlantic side  holds  
  we may be in   business

If that happens... I see signs of a flexing and waining PNA for us this year, which is a good thing. Do not see that tele as dominant feature either way.

As PSU mentioned, Atlantic looks more neutral driver than the killer it’s been (really past two winters). If Nina weakens as we move through Jan then west pac riding becomes more likely and we might score.

[poolz1]

18z gfs op puts a real hurt'n on the spv...  I get all the caveats but good to see op runs pick up on the mid month attack.  The more robust the better....Lets throw a major wrench in this nina!

[psuhoffman]

Imo this here is our best chance of a snow event before Xmas. 

This is EPS but GEFS is similar for that range. Nice -NAO. Can see the likely cutter still lingering in the 50/50 domain as the next wave approaches.  It’s not perfect.  The pac is already less than ideal but it hasn’t gone to complete crap yet here.  It’s a decent look. 

[psuhoffman]

1 hour ago, WxWatcher007 said:

FWIW, the Para continues to show potential in that 14th to 16th range. It's right on the heels of the weekend cutter. 

The tpv being that far west will promote ridging unless the NAO really tanks so we need the spacing to work.  If the waves are too spread our they all cut like the Gfs op run

[Maestrobjwa]

Ha...both almanacs call for a storm on those dates...lol Yeah I know, I know...but whenever the medium-long range models potential on dates that coincide with the Almanacs (in this case both of them), I can't resist mentioning it 

[Ji]

Ggem gets us snow to rain