December 2019 Med/Long Range Disco

[psuhoffman]

2 hours ago, C.A.P.E. said:

0z EPS  at the end of the run looks pretty decent. A workable pattern with a split flow and probably normal temps for the east. 0z GEFS is similar but has a deeper western US/EPac trough and hangs onto a weak EC ridge. Looks good up top though, NA in particular. Both have colder air building into the western half of Canada courtesy of the EPO ridge. It's a waiting/monitoring game now to see how long it takes to get some of that cold delivered to the eastern US. Verbatim, the EPS look would probably put us back in the game a bit sooner.

Almost every analog to the current pattern went on to have persistent blocking that winter. There are also a lot of 1960s years in the analogs which I find interesting because back in early November when I was looking at analogs to current sst and qbo the best ones were in the 60s but I tossed them because between climo change and the -NAO of that decade it’s dangerous using those years. But I do feel more and more optimistic we get high latitude help this winter. Issue is do we ever get the pac right at the same time. 

ETA:  weeklies are useless buy say no. We get a good pac for 10 days but the Atlantic is atrocious. Then we get NAO help and the pac goes to crap. Issue on weeklies is the pv never gets displaced it just cycles back and forth wrecking either pac or atl pattern. I don’t give it any weight but that’s one way to epic fail. 

[nj2va]

2 hours ago, C.A.P.E. said:

0z EPS  at the end of the run looks pretty decent. A workable pattern with a split flow and probably normal temps for the east. 0z GEFS is similar but has a deeper western US/EPac trough and hangs onto a weak EC ridge. Looks good up top though, NA in particular. Both have colder air building into the western half of Canada courtesy of the EPO ridge. It's a waiting/monitoring game now to see how long it takes to get some of that cold delivered to the eastern US. Verbatim, the EPS look would probably put us back in the game a bit sooner.

If we can get stronger ridging over Scandinavia (or the ridge bridge), would that help displace TPV further south?   That's something I've been following in the uber LR as I would think that would help us.  

[Bob Chill]

8 minutes ago, nj2va said:

If we can get stronger ridging over Scandinavia (or the ridge bridge), would that help displace TPV further south?   That's something I've been following in the uber LR as I would think that would help us.  

Gefs general idea is a decent invasion of arctic air. The spread shows all outcomes with the cold centered westerer and easterer. 

[frd]

30 minutes ago, psuhoffman said:

weeklies are useless buy say no.

 

They were persistent last year when predicting a cold and epic pattern, we know how that turned out, maybe they are more accurate in a warmer climate, LOL.

I do think the 1960's analogs are intriguing. 

On a brightener note, there are some positive changes taking place. + IOD  weakening, but slowly, and some hints that the vortex gets pressured again. No SSWE in sight, and if one were to occur at all this season I place my bet on Feb, or even March. 

Really believe the fate of significant and sustained winter period(s) is going to ride on the weakening + IOD and more robust  and favorable MJO phase(s) and progressions. Also, need to achieve and maintain some sort of -AO and intervals of +PNA. 

Seeing the deep cold air and snow depth increases once again being modeled over Siberia is a plus for Jan.  Maybe Jan evolves similar to November but a week behind and in our peak climo.

The biggest tip off today might be the better trends of the AO for the second half of the month and at least not a horrible PNA. moving to neutral at least.      

[frd]

If this goes down again could be a plus for us.  Bringing  this up not because of the potential of this leading to a SSWE, ( which again I put at low odds ) but more so the benefit of anticyclonic wave breaking, etc.    

 

[Ralph Wiggum]

1 hour ago, psuhoffman said:

Almost every analog to the current pattern went on to have persistent blocking that winter. There are also a lot of 1960s years in the analogs which I find interesting because back in early November when I was looking at analogs to current sst and qbo the best ones were in the 60s but I tossed them because between climo change and the -NAO of that decade it’s dangerous using those years. But I do feel more and more optimistic we get high latitude help this winter. Issue is do we ever get the pac right at the same time. 

ETA:  weeklies are useless buy say no. We get a good pac for 10 days but the Atlantic is atrocious. Then we get NAO help and the pac goes to crap. Issue on weeklies is the pv never gets displaced it just cycles back and forth wrecking either pac or atl pattern. I don’t give it any weight but that’s one way to epic fail. 

The SPV/TPV outlook is nearly impossible to forecast. However, the SPV looks to get pummeled with a squeeze (almost splits!) and that is under 240 hours so it may have some credence. If recent past history from Nov is any indictation, that *should* have some effect on the TPV. We saw last month a similar setup where the TPV was trying to anchor and solidify but when the same SPV beatdown came along it actually caused the TPV to split. There were actually 3 lobes at one point iirc. 

[frd]

If the ECM is correct regarding the MJO progression it will take some time to flip colder again, as others have mentioned here. However, this certainly does not look like some of the craziness depicted last year at this time when we started to warm up and the MJO phases were all warm, and at a high amplitude. Not to mention, the movement in those warm phases was VERY slow. 

From bluewave :

<<

Next few days should be our last Arctic air mass for a while. The MJO forecast to  move near phase 6 means mostly a mild Pacific influence into the longer range. 

>>

[WxUSAF]

^thats a weak amplitude wave however. If those strat forecasts are right, we could get an EPO driven arctic shot just before New Years due to the strong wave 2 hit on the strat PV.

[frd]

6 minutes ago, WxUSAF said:

^thats a weak amplitude wave however. If those strat forecasts are right, we could get an EPO driven arctic shot just before New Years due to the strong wave 2 hit on the strat PV.

Saw that this morning. Some interesting things going on up top, can almost see an evolution similar to November happening in Jan at some point. 

Ural block nice to see . Some serious cold may come over the top in Jan., similar to November.  Another -NAM state accompanied by an improving Pac would be most welcomed.  Looking like the table resets in Siberia and then the move is on.  

 

[Bob Chill]

18 minutes ago, WxUSAF said:

^thats a weak amplitude wave however. If those strat forecasts are right, we could get an EPO driven arctic shot just before New Years due to the strong wave 2 hit on the strat PV.

Yea, amplitude matters. The MJO is far from a 1:1 correlation with our winter wx but the correlation def goes up with amplitude. That plot above is weak sauce. 

And I totally agree with your second point. All 3 global ens show some sort of decent front clearing between xmas and new years. Would make sense and could be the beginning of the process that carves the upper levels into something more workable. It's not going to be quick and easy so if we get a good front followed by another mild shot before next front it would be pretty normal and the more likely way to return to winter versus the arctic hounds blasting through and hanging out for weeks. That said, it's going to be really boring around here for the next 7-10 days me thinks. 

[psuhoffman]

1 hour ago, nj2va said:

If we can get stronger ridging over Scandinavia (or the ridge bridge), would that help displace TPV further south?   That's something I've been following in the uber LR as I would think that would help us.  

A squeeze play between the Scand/East NAO ridge and the EPO ridge could displace the TPV either across the pole or south.  Either is preferable IMO. Ideally south but going into January North America can manufacture "enough" cold for us to get snow even absent any TPV in our area.  During the epic run in 2010 the TPV was way up in NW Canada at times and then got squeezed across the pole.  Without all the snowcover we probably would have been 50 degrees most days during that run.  I would take perfect storm track over perfect cold air source mid winter.  Cold air around won't help us if storms are cutting to our northwest.  I would rather have no TPV than an unfavorably placed one from New Years to Mid February.  Outside that period you probably need a favorable TPV to get enough cold here.  The issue on the euro for most of the next 2 weeks is the TPV is located at the worst latitude.  When its to the west it pushes the EPO ridge too far west to help and floods NAM with pac puke.  When it slides east it presses the NAO ridge too far east to help much and the EPO ridge is still being prevented from progressing far enough into NW NAM to overcome that.  It needs to get out of there.  Towards the VERY end of the runs the ensembles hint at movement on that...but its in the fantasy land range.  One saving grace is that will become less critical later in winter.  The TPV location isn't as crucial for our snowfall the second half of winter.  

 

 

[WxUSAF]

15 minutes ago, Bob Chill said:

Yea, amplitude matters. The MJO is far from a 1:1 correlation with our winter wx but the correlation def goes up with amplitude. That plot above is weak sauce. 

And I totally agree with your second point. All 3 global ens show some sort of decent front clearing between xmas and new years. Would make sense and could be the beginning of the process that carves the upper levels into something more workable. It's not going to be quick and easy so if we get a good front followed by another mild shot before next front it would be pretty normal and the more likely way to return to winter versus the arctic hounds blasting through and hanging out for weeks. That said, it's going to be really boring around here for the next 7-10 days me thinks. 

Yup, looks like 5-6 cold+dry days coming up and then a week of AN Pac puke and then probably things start reshuffling. It is nice that we are seeing the exit door from the wretched Pac open before we even walk through the entrance. But need some patience for the next 2 weeks. With the clear tendencies toward HL blocking and an active pattern this year so far, I remain pretty bullish on at least an “average” winter snowfall wise. 

[frd]

Will get more data soon but the +IOD is weakening. Really feeling this is a potential game changer.  It was more than likely the # 1 pattern driver.

It also causes an acceleration of the jet and interferes with ideal West Pac forcing. 

That looks to be slowly changing.   

The various modeling weakens the + IOD , but not to below the threshold value until Feb 2020  with universal agreement to below 0.4 C occurring  in March 2020

I am hopeful either the weakening is more rapid, or the + IOD weakens enough to allow a more favorable West Pac regime to unfold sooner. 

http://www.bom.gov.au/climate/model-summary/#tabs=Indian-Ocean&region=NINO34

Indian Ocean Dipole (IOD) outlook

Sea surface temperatures in the Indian Ocean have shown patterns consistent with a positive IOD event since the end of May, with the IOD index exceeding the positive IOD threshold from mid-July. The event peaked in mid-October with a weekly index value of +2.2 °C. Despite recent weakening, the latest value (for the week ending 8 December) is +0.9 °C, persisting above the +0.4 °C threshold for the 19th consecutive week.

Most models suggest positive IOD index values are unlikely to return to neutral until January or February. This is much later than would typically be expected with an IOD event, and is due to the delayed transition of the monsoon trough into the southern hemisphere. This transition typically happens in early December, heralding the imminent decay of any active IOD event, but has yet to be observed in 2019.

 

  

[frd]

 

One final note about the + IOD decay. Echoes the thoughts above.

 

 

 

 

[psuhoffman]

I'll try to add some more "hopeful" interjection wrt where we are and where this might go here.  Some of you have already hit on the current "goings on" in the strat and tropical forcing so I will just add some support to that with historical reference.  I have already mentioned that almost all the analogs to late December patterns similar to this one went on to have persistent blocking the rest of winter.  So that supports what we are seeing wrt PV disruptions and the tropical forcing heading towards better phases in January.  But another factor on our side, a similar pattern to this one wouldn't be as hostile later in winter.  There are a lot more examples of the atlantic winning over the pacific from Mid January on than this time of year.  December 2009 only worked because we had pacific help ALSO.

But look at  Feb 2010 

TPV in roughly the same location in NW Canada.  Awful Pac setup.  And it wouldn't have been a cold period, absent the snowcover we probably would have been near or above normal.  Similar to this coming week.  But that look can work later in winter when the whole thermal profile on NAM is colder in general and the jet is more susceptible to a blocked flow.  I do think for that to work at some point in January we will need an EPO dump of cold into NAM prior to such a look to set the table.  But assuming the PAC doesn't run the table in its current crap state if we can get the same general pattern as we have had recently to repeat the second half of winter we would have a much more favorable outcome imo.  

[psuhoffman]

8 minutes ago, WxUSAF said:

 With the clear tendencies toward HL blocking and an active pattern this year so far, I remain pretty bullish on at least an “average” winter snowfall wise. 

That’s exactly what I’m hanging my hat on for now. Still cautiously optimistic for the winter on the whole. 

[Bob Chill]

12z gfs op is an unmitigated disaster in the LR. It's like 5 steps away from a good pattern at the end. It's just an op and way outside useful range but I don't like seeing runs that end like that. lol

[North Balti Zen]

24 minutes ago, Bob Chill said:

12z gfs op is an unmitigated disaster in the LR. It's like 5 steps away from a good pattern at the end. It's just an op and way outside useful range but I don't like seeing runs that end like that. lol

On an up note, we will get blocking in mid April so we got that going for us...

[WxUSAF]

24 minutes ago, Bob Chill said:

12z gfs op is an unmitigated disaster in the LR. It's like 5 steps away from a good pattern at the end. It's just an op and way outside useful range but I don't like seeing runs that end like that. lol

Don’t scare the weenies Bob. 12z GEFS looks pretty good towards NYE actually. Faster transition to a workable Pac than previous runs as well.

[WxUSAF]

7 minutes ago, WxUSAF said:

Don’t scare the weenies Bob. 12z GEFS looks pretty good towards NYE actually. Faster transition to a workable Pac than previous runs as well.

Actually by the end of the GEFS run its a good pattern for snow, and it’s a step or two away from a VERY good pattern for snow

[Bob Chill]

5 minutes ago, WxUSAF said:

Don’t scare the weenies Bob. 12z GEFS looks pretty good towards NYE actually. Faster transition to a workable Pac than previous runs as well.

GEFS looks fine. We just don't know exactly how things will evolve. There are quick ways back to something serviceable and then there's the long drawn out ways... GFS op showed one of the long drawn out ones... One thing the 12z gefs went nuts with is the Iceland ridge. Must be strong consensus for that considering the anomalies showing up way out in time. We'll probably end up fighting the Pac longer than we want with troughs digging but that won't last forever. Park the TPV over or SE of hudson and we can get back to tracking. 

[frd]

1 minute ago, Bob Chill said:

Park the TPV over or SE of hudson and we can get back to tracking. 

Webb believes this will happen and expects the models to go to this outcome. In play are model biases and such. He believes the progression is brought about by a combination of wave breaking and an improving Pac / tropical forcing regime, in part due to the weakening +IOD  Speculating myself if maybe some sort of - EPO delivery of intense cold is going to get trapped under a block in early to mid Jan. leading to a  threat window ( over-running/ clipper /  colder version Miller B , etc.   )   

[frd]

 

This makes sense. Hope it progresses. 

  

Also of interest regarding the SER

 

 

 

[Ralph Wiggum]

1 hour ago, Bob Chill said:

12z gfs op is an unmitigated disaster in the LR. It's like 5 steps away from a good pattern at the end. It's just an op and way outside useful range but I don't like seeing runs that end like that. lol

OP runs that are weenie runs past 300 hours with the 384 hour fantasy blizzard don't normally work out either....so there's that.

[Bob Chill]

15 minutes ago, frd said:

Webb believes this will happen and expects the models to go to this outcome. In play are model biases and such. He believes the progression is brought about by a combination of wave breaking and an improving Pac / tropical forcing regime, in part due to the weakening +IOD  Speculating myself if maybe some sort of - EPO delivery of intense cold is going to get trapped under a block in early to mid Jan. leading to a  threat window ( over-running/ clipper /  colder version Miller B , etc.   )   

It's a logical progression and the CFS weeklies & monthlies agree that Jan will be some version of that. Euro weeklies have a similar idea at times but also show that we may be fighting the western trough off and on through the end of Jan. My gut instinct is telling me that it will take longer to get out of the western trough regime and could frustrate us through the end of the year into early Jan. Inside of the GEFS mean is an equal spread of winter returning and frustrating western trough. Total coin flip here:

[Bob Chill]

2 minutes ago, Ralph Wiggum said:

OP runs that are weenie runs past 300 hours with the 384 hour fantasy blizzard don't normally work out either....so there's that.

Absolutely and all I was pointing out was the possibility of nasogood stuff continuing. However, when we're looking/waiting for a pattern shift it does typically start showing up on long range ops and that helps confirm that the ens may be more right than wrong. The thing that sucks right now is we have to wade through 10-14 days of a shutout pattern and a pretty bad one at that. I'd love to talk about the more reliable mid range but that's not in the cards so we're stuck picking apart uber long range ops and ensembles for a while. We do it pretty much every year and hopefully this is the only/last time.

I can deal with the rest of Dec sucking no problem. Start bleeding into mid Jan and it's going to get testy an restless up in here. 

[yoda]

12z EURO has decided to at least come part way up the coast for the late weekend into early next week deal now... but no cold air to be found lol

144 its just south of ILM with the h5 low close behind it

[Maestrobjwa]

21 minutes ago, Bob Chill said:

Absolutely and all I was pointing out was the possibility of nasogood stuff continuing. However, when we're looking/waiting for a pattern shift it does typically start showing up on long range ops and that helps confirm that the ens may be more right than wrong. The thing that sucks right now is we have to wade through 10-14 days of a shutout pattern and a pretty bad one at that. I'd love to talk about the more reliable mid range but that's not in the cards so we're stuck picking apart uber long range ops and ensembles for a while. We do it pretty much every year and hopefully this is the only/last time.

I can deal with the rest of Dec sucking no problem. Start bleeding into mid Jan and it's going to get testy an restless up in here. 

But again, is this really so far from what we normally see? To me, punting late December has been pretty much the norm for the last 7 or 8 years, right? (and even historically we seemed to have to punt that part of the month more!)

[Weather Will]

I just looked at the latest 10 day EURO.  Not white, but not a torch either.  Highs on Christmas in the upper 30s this run, not 60.

[87storms]

14 minutes ago, yoda said:

12z EURO has decided to at least come part way up the coast for the late weekend into early next week deal now... but no cold air to be found lol

144 its just south of ILM with the h5 low close behind it

the 500 map at least on the gfs was not very inspiring.  the energy in the west just splits off and takes their own path east.  need at least a partial phase.