December 2019 Med/Long Range Disco

[Scarlet Pimpernel]

7 hours ago, Ralph Wiggum said:

Thru 240 on the EPS/GEFS/GEPS pattern isnt terrible. AO looks to go from positive back to neutral then negative. PNA starts then ends positive. Big EPO ridge...Aleutian low. Atl side is meh imo...nothing too exciting yet no major red flags either. Would be nice to get the NAO ridge to work in tandem with the favorable PAC teleconnections but maybe as we move thru the month.  Again, thru day 10 no significant concerns and certainly not a shutout look. And that takes us closer to mid Dec so no complaints. Those day 10+ progs with collapsing patterns and PAC air flooding the US keep being pushed back for now.

 

1 hour ago, Ralph Wiggum said:

First red flag on the EPS....day 10 screaming PAC jet into the West coast....western US and Canada flooding with PAC air. Rather get it out of the way now I suppose. Many pros seem to think big changes for the better are coming later in Dec.

 

One might get whiplash from these two contrasting posts...a mere few hours apart (and apologies...sort of...for singling yours out!)!  But seriously, having not followed much so far as we get into winter, it's hard to make too much of anything one way or another as this month progresses.  And hope that's right about better changes later in the month.  I think the general consensus from what I gleaned reading in here lately is that we'll have a period of "not so great" after this week, but perhaps transitioning into better later in the month.  Maybe I misinterpreted that, but it's the sense I got.  As long as we don't end up with week after week after week of "Pac Puke" like last year (phrase compliments of Bob Chill!), and then have to waste more weeks "recovering" from that!  Or another Christmas Eve like 2015, where it was actually uncomfortably humid and damp.  Lately, snow in December around these parts seems almost like a bonus.  Even a small amount.

Good news is, maybe even if it's relatively mild, I can get a few miles of bike riding in now and then before we go full Jebman with extreme cold and deep snow pack (and of course I'd root for that)!! 

[Bob Chill]

5 minutes ago, Always in Zugzwang said:

 

 

One might get whiplash from these two contrasting posts...a mere few hours apart (and apologies...sort of...for singling yours out!)!  But seriously, having not followed much so far as we get into winter, it's hard to make too much of anything one way or another as this month progresses.  And hope that's right about better changes later in the month.  I think the general consensus from what I gleaned reading in here lately is that we'll have a period of "not so great" after this week, but perhaps transitioning into better later in the month.  Maybe I misinterpreted that, but it's the sense I got.  As long as we don't end up with week after week after week of "Pac Puke" like last year (phrase compliments of Bob Chill!), and then have to waste more weeks "recovering" from that!  Or another Christmas Eve like 2015, where it was actually uncomfortably humid and damp.  Lately, snow in December around these parts seems almost like a bonus.  Even a small amount.

Good news is, maybe even if it's relatively mild, I can get a few miles of bike riding in now and then before we go full Jebman with extreme cold and deep snow pack (and of course I'd root for that)!! 

Long range looks like perfectly typical early winter in these parts. Not too warm, not too cold, and not snowy without a fluke. As we move later into the year, the same type of pattern has an easier time working out in some fashion.

For now we just sit back and wait. Prob for at least 2 weeks. 

[Scarlet Pimpernel]

42 minutes ago, Bob Chill said:

Long range looks like perfectly typical early winter in these parts. Not too warm, not too cold, and not snowy without a fluke. As we move later into the year, the same type of pattern has an easier time working out in some fashion.

For now we just sit back and wait. Prob for at least 2 weeks. 

Exactly.  Which is why I'm more or less in your camp, just sit back and see how things go.  As long as it's not looking like wall-to-wall crap in the longer range, we should be OK.  At this point in the month (only the 1st!), I'm not overly enthused nor am I concerned.  Like I said...and as you've mentioned many times..."good" snow in the 1st half of December is climatologically not exactly the easiest in any year (barring something extreme like 2009).  I tend to pay more attention as we get toward Christmas, when the medium range is getting into the last part of the month and first part of January.  And you're absolutely correct, the same kind of pattern later in the month is easier to produce something snowy than it is now.  A bit more forgiving, as it were.  We don't require quite so much deviation from climo by then.

[Bob Chill]

If this spread is where we are in 2 weeks then we're in the game at a time where we don't need an impressive airmass

 

No signs of the stout blocking we've recently had returning anytime soon but I'm not picky early season and what I'm seeing is improving chances for some sort of event as we approach mid month. 

[aldie 22]

1 minute ago, Bob Chill said:

If this spread is where we are in 2 weeks then we're in the game at a time where we don't need an impressive airmass

 

No signs of the stout blocking we've recently had returning anytime soon but I'm not picky early season and what I'm seeing is improving chances for some sort of event as we approach mid month. 

Man if its chilly around Christmas and there are flakes in the air I call that a win. I know there are some clowns on here that would be disappointed but whatever. Let it feel like the season and I'm happy 

[Bob Chill]

Just now, leesburg 04 said:

Man if its chilly around Christmas and there are flakes in the air I call that a win. I know there are some clowns on here that would be disappointed but whatever. Let it feel like the season and I'm happy 

It's always perspective. I was never impressed overall leading into this year and expected Dec to really suck until recently. I'm with you. If we don't torch second half and have some winter wx of any kind during the last 10 days of the month it will be satisfying. 

It's a bit of a shame the current storm didn't happen 2 weeks later. We'd be shoveling 2-6" right now. Heh

[osfan24]

3K NAM has some snow showers for Northern MD. Even some light accumulations. Interestingly, it's not as bullish northeast of us. Still some big totals, but nothing approaching 20+.

[Ralph Wiggum]

Ens means are picking up on the -AO sustaining itself thru Day 10 as well as a growing NAO ridge days 6-10. Wait and see situation as Bob says. Nothing too concerning. The EPS from 12z yesterday with the AN 850s out West across N America maybe a blip. More of a PNA ridge trying to show again. Guess a different wording yesterday would have been preferred such as "hope to see some amplification in the E Pac and not a flat flow into N America". The most favorable reoccurrences are the Aleutian low/EPO ridge, WAR which is displaced N more than last few years and is helping feed the ridge near Greenland at times, and the split flow off the West Coast. All have faded briefly at times but seem to be gaining steam as background states as they continue to show up. Unfavorable looks that surface now and then on the ens means continue to be pushed out past Day 10. Opposite from 2018-19 so far irt to good vs bad. Always chasing unicorns that got pushed back day 10+ last year. This year just the opposite so far. 

[showmethesnow]

GEFS really knows how to run a PAC torch of the N Hemisphere. Okay, maybe not so much.

 

Euro on the other hand. 

 

Despair runs rampant in ville as the King has spoken. 's are picking their spots along the cliff as reservations have never been better for so early in the season for @WxWatcher007's luxurious resort. And yet... Off in the shadows Showme is pulling out his cold weather survival gear, just to be on the safe side, and looking speculatively at his snowblower and snow shoes. But alas, Showme decides to hold off on the snowblower and snowshoes for the time being but has made a mental note of where they are located for quick retrieval.

's are astounded by Showme and point and laugh mockingly at their fellow 's antics. After all the King has spoken and his decrees are absolute. Yet Showme ignores the ridicule as he is following the subtle clues left behind from the models like a Wintertime Sherlock Holmes. If he thought the 's would listen he would present his evidence thusly.

***************************************************************************

Knowing the bias'/tendencies of the models as well as actual verification in real time weather this was something I speculated on 8 days ago as far as what we would see with the PV despite what the models were presenting at the end of their extendeds. Felt the odds favored a piece of PV over on the other side of the globe between N Russia and the pole. That we would see a piece dropping fairly deeply into central/eastern Canada. And that we would see an extension if not a piece of PV into the Aleutians. Note I also I felt we would see more pronounced ridging through the EPO and NAO domains.

 

And this is what is currently projected through this same time period (day 7). We are seeing more pronounced ridging through the EPO and NAO domains and the PV's are located where I speculated on with one somewhat exception. Though the models have slowly moved the PV in Canada southward run over run it is still has not dropped as far south as I thought we may see. If the models are somewhat right with the other features the PV drop will be probably be the key as far as PAC flood through the CONUS/or not as well as a potential for a very cold shot of air into the Midwest and East.

 

 

 

Now below we are looking a day later (Day 8) on the GEFS which is probably the key time frame for what we see later. Note that we see a full latitude deep trough through the Midwest. If you note the deep neg blue/purple anomalies running down from the PV into the Lakes this is an indication that this trough is having a decent influence on the PV which will tend to pull it southward and drag it eastward along with it. I will show you the results of this in the following days shortly.

 

 

Now we have the EPS and its representation at day 8. Note that we are seeing the same general look with the full latitude trough but we are not seeing near the same influence from the trough on the PV as we saw with the GEFS. Anamolies aren't as strong and they do not extend nearly as far south as the GEFS. So interaction between the two features is minimal.

 

So now we have the GEFS 2 days later (day 10) so let's see what the results of more interaction between the PV and that trough produced. What we see is that the PV has extended N/S towards the trough that extends into the east. So though we are still seeing the PAC flow through the CONUS we also have a mitigating North flow from the Arctic regions around the EPO. This setup puts a wall up against the PAC flow in the central US as a trough and the cold sets up in the Midwest and East and shoves the PAC flow down into the deep south.

 

Now what do we see with less interaction between the PV and the trough? Below we have the EPS. Note that with less trough influence to drag it southward and eastward what we have is a broad W/E PV setup through Canada extending towards the piece of PV over the Aleutians. This is effectively shutting down the north flow from the around the PV so we are seeing the PAC air given free reign to spread eastward through the CONUS. The above and below are the difference between a CONUS wide torch and a torch in the west and cold in the East.

 

Now which is right? I myself am favoring the GEFS at this time. GEFS has been stepping towards its current look for several days now. Though the EPS doesn't paint a pretty picture at this time it has also been stepping towards the GEFS solution though it is still lagging somewhat behind. Now I mentioned the possibility that we could actually see a major cold shot into the Midwest/East. I tend to believe we are going to see the PV farther south then currently projected on the models. And when I see some of the large height builds through the NAO domain and into Northern Canada and the pole on some of the op runs I believe that the models may be picking up on this. The question is, does it get far enough south as to where the trough's influence as it moves eastward is enough to draw it deep into the trough. If that is the case we would probably be looking at the PV rotating down into the Lakes or eastward delivering much colder anomalies then currently projected on the GEFS's above map.

Now the all important question. What about snow? Right now the setup during this time is indicative of a storm in the Midwest/East potentially a strong one at that. At this time though I would probably favor somewhere to our west. Trough/PV placement as well as the WAR would argue for this. BUT... Some things I am seeing suggest it may not be as cut and dry as that. But it is to early still to focus on that aspect as I think there is a strong possibility we are going to see some significant changes within the models in the coming days if in fact the models do move towards a deeper pv. 

So in a nutshell. At the bare minimum I favor cold in the east in the extended despite what the Euro has to say. The question is, how cold and will there be snow?

[Climate175]

1 hour ago, losetoa6 said:

And you line cold air nearby up with a fairly active and wet storm track like below ....Our chances of timing something up increases for sure. We r getting into mid December...climo starting to tip in our favor .

0z Gefs day 8-15

 

Just a matter of time indeed.

[showmethesnow]

GFS rotates the PV down to just north of the Lakes as it responds to the trough running through the central part of the country.

Dishes out some significant cold into the Midwest and East..

 

[psuhoffman]

11 minutes ago, losetoa6 said:

Almost right on Cue op Gfs has a impressive cold dump into the Conus starting around  day 8 . Hopefully there's more like it to come

 

9 minutes ago, showmethesnow said:

GFS rotates the PV down to just north of the Lakes as it responds to the trough running through the central part of the country.

Dishes out some significant cold into the Midwest and East..

It’s also close to a storm setup. If that PV lobe can end up just a slight bit east of where it is on this prog that is a good look to keep that system out west to stay under us. Been watching this evolve closer to a good look the last 36 hours. So far the euro isn’t buying it as much but it’s moving the right way too.  I know using an op run at range is risky but until ncep updates the GEFS we don’t really have an ensemble to look at for the dynamic core FV3 version of the GFS.

[showmethesnow]

It's an op at range so take this comment for what it is worth. I like what I am seeing on the GFS from the roughly day 8 cold shot and onward through the extended. Very active pattern, PAC is being very cooperative, eastern trough/western ridge and besides a brief 1 1/2 day torch at the very end we are generally looking at cold to very cold in the east. Day 8-16 has the potential to surprise.

[showmethesnow]

This is what I call a cooperative PAC. 

Day 6

 

Day 10 1/2

 

Day 14 1/2

 

Have the initial troughing towards Hawaii at day 6 which bumps up the ridging into the Northern PNA and EPO domains. Before this ridging can totally breakdown we see another trough setup towards Hawaii at day 10 1/2 thus reinforcing the ridging in the general EPO/N PNA regions. And yet again, at day 14 1/2 we have troughing again as well as ridging. 

 

 

[jaydreb]

Pretty stout PNA ridge in medium-range on the GEFS.  

 

[WxUSAF]

Euro gives areas N of DC a dusting overnight Tuesday into early Wednesday.

[LurkerBoy]

Things be looking up a bit in model world. 

[WxUSAF]

Haven’t seen Eps past D10, but inside of D10, there’s a clear trend to a stronger -EPO,-NAO, and -AO relative to previous runs and any pac puke flood gets cankicked to D10 yet again. Yes, we will have a 24hr torch next week with the cutter, but cold air is around. 

Eps actually quite a bit more bullish than GEFS with the -AO, while GEFS more bullish on -EPO. 

[Bob Chill]

47 minutes ago, WxUSAF said:

Haven’t seen Eps past D10, but inside of D10, there’s a clear trend to a stronger -EPO,-NAO, and -AO relative to previous runs and any pac puke flood gets cankicked to D10 yet again. Yes, we will have a 24hr torch next week with the cutter, but cold air is around. 

Eps actually quite a bit more bullish than GEFS with the -AO, while GEFS more bullish on -EPO. 

Everything is right down the middle. Not bad enough to worry and not good enough to like it. lol. I'm not thinking we have much of a chance for the next 2 weeks unless something runs the gauntlet. Would be nice to get the atl & pac to play nice together this month. Sometime around the 24th-25th would be acceptable. 

[Ralph Wiggum]

2 hours ago, jaydreb said:

Pretty stout PNA ridge in medium-range on the GEFS.  

 

But that Atlantic side 

[Ralph Wiggum]

6 minutes ago, Bob Chill said:

Everything is right down the middle. Not bad enough to worry and not good enough to like it. lol. I'm not thinking we have much of a chance for the next 2 weeks unless something runs the gauntlet. Would be nice to get the atl & pac to play nice together this month. Sometime around the 24th-25th would be acceptable. 

Stole my thoughts. Pac and AO  look great Atl goes to meh. Atl looks great and AO/Pac go to blah. Not a loss which isnt a bad thing. A split down the middle for now is acceptable. Need both sides to work in tandem this time of year. But as winter climo nears we can find ways to score without a tag team combo.

[WxUSAF]

15 minutes ago, Ralph Wiggum said:

But that Atlantic side 

Need some WAR or SE ridge during a big -EPO period or it’s just cold and dry. Take a look back at the pattern for last November’s early season snow. Big WAR, which is what brought the storm, but we had a good cold air source and so it snowed. Similar deals in 13-14 and 14-15. If it’s going to be a EPO dominated pattern, got to accept some cutters and cold/dry.

[Ralph Wiggum]

6 minutes ago, WxUSAF said:

Need some WAR or SE ridge during a big -EPO period or it’s just cold and dry. Take a look back at the pattern for last November’s early season snow. Big WAR, which is what brought the storm, but we had a good cold air source and so it snowed. Similar deals in 13-14 and 14-15. If it’s going to be a EPO dominated pattern, got to accept some cutters and cold/dry.

I realize about the WAR but before we enter prime climo an anti cyclone in the 50/50 spot usually hurts us more than helps especially with ssts still relatively warm. Now this look in another 3 weeks and we could probably get away with it. Love that Pac look tho.

[WxUSAF]

21 minutes ago, Bob Chill said:

Everything is right down the middle. Not bad enough to worry and not good enough to like it. lol. I'm not thinking we have much of a chance for the next 2 weeks unless something runs the gauntlet. Would be nice to get the atl & pac to play nice together this month. Sometime around the 24th-25th would be acceptable. 

I’m wondering how much this Pac puke can kick is due to the conflicting tropical forcing signals. Maybe Eps keeps expecting the MJO to get into torch phases (and maybe the “true” MJO wave is doing that) and so expects a Pac flood, but as we get closer in time, that Indian Ocean standing wave still ends up being the tail wagging the dog and the MJO forcing itself is overwhelmed. 

Either way, it’s probably having the net effect of turning what otherwise would be a December torch into a fairly seasonal week or two with low, but nonzero snow chances if we can time up some cold air and a southern wave. Certainly looks Nino-ish with active southern stream. I’m cautiously optimistic we get a fun event or two this month.

[Ralph Wiggum]

7 minutes ago, WxUSAF said:

I’m wondering how much this Pac puke can kick is due to the conflicting tropical forcing signals. Maybe Eps keeps expecting the MJO to get into torch phases (and maybe the “true” MJO wave is doing that) and so expects a Pac flood, but as we get closer in time, that Indian Ocean standing wave still ends up being the tail wagging the dog and the MJO forcing itself is overwhelmed. 

Either way, it’s probably having the net effect of turning what otherwise would be a December torch into a fairly seasonal week or two with low, but nonzero snow chances if we can time up some cold air and a southern wave. Certainly looks Nino-ish with active southern stream. I’m cautiously optimistic we get a fun event or two this month.

I will say this...those sustained AN temp regime looks and blue balls over the N Pole keep getting pushed back and there is nary a sign of any SE ridge which many of the warm December forecasts were banking on. This cant be a bad thing as now the next 10 days look ok and takes us to almost mid December. It's a little premature for us to celebrate but many of those warm Dec forecasts may be quickly losing steam....no pun intended.

[Bob Chill]

Just now, WxUSAF said:

I’m wondering how much this Pac puke can kick is due to the conflicting tropical forcing signals. Maybe Eps keeps expecting the MJO to get into torch phases (and maybe the “true” MJO wave is doing that) and so expects a Pac flood, but as we get closer in time, that Indian Ocean standing wave still ends up being the tail wagging the dog and the MJO forcing itself is overwhelmed. 

Either way, it’s probably having the net effect of turning what otherwise would be a December torch into a fairly seasonal week or two with low, but nonzero snow chances if we can time up some cold air and a southern wave. Certainly looks Nino-ish with active southern stream. I’m cautiously optimistic we get a fun event or two this month.

No persistence to rely on yet in North America so our brains can't see through the computers. lol

Had a blocky pattern in general going for a few weeks that's evaporated and now looks like progressive is going to take over for the next few weeks. Both were modeled "ok" in the D10-15 range so we can prob trust the current d10-15 general pattern showing up. Which isn't very exciting but if anything (as you've already said), the big warning flags in the long range keep getting muted and delayed. Could be a clue that the general NA pattern has a tendency to be more amplified. 

[poolz1]

It has been a bit of a trend today for the D8-10 period.  GFS increases blocking again at 18z and shoves the Canadian vortex south into the N plains.  Looks to roll east from there.  Lets kick the closed low out of Cali and attack that arctic high!

[Ji]

18z looks like it might deliver a happy hour lol

[Bob Chill]

3 minutes ago, Ji said:

18z looks like it might deliver a happy hour lol

But you said the southern stream was dead

[frd]

6 minutes ago, poolz1 said:

It has been a bit of a trend today for the D8-10 period.  GFS increases blocking again at 18z and shoves the Canadian vortex south into the N plains.  Looks to roll east from there.  Lets kick the closed low out of Cali and attack that arctic high!

A few interesting things to keep an eye on :

The mid month period when there are signs of a drop in the AO along with a +PNA interval. Some favorable action too from the strat may work its way down to a degree. 

Meanwhile, interesting progressions with the warming as it transpires in terms of the Canadian vortex and trop / strat vortex over Siberia/Scandy , as mentioned by Hugo. 

Also, the elongation and the movement of the trop vortex has my interest as well, in a backdrop favorable to keep the vortex perturbed.

Below are several relevant recent releases on the above.