December 2019 Med/Long Range Disco

[Ralph Wiggum]

Just some minor run-to-run changes:

[CAPE]

11 minutes ago, Ralph Wiggum said:

Just some minor run-to-run changes:

 

I know you know this, but ops at range tend to do this.

[CAPE]

@showmethesnow

Not bad. Nice EPO ridge building, and the NAO looks...neutral.

[Ralph Wiggum]

18 minutes ago, C.A.P.E. said:

I know you know this, but ops at range tend to do this.

Of course. But that was a bigger jump than normal and a hint as to where the EPS may go. 

[Maestrobjwa]

1 hour ago, frd said:

Many times the state of the AO in December provides clues to the AO state for Jan and Feb. 

Having measurable snow in our area, such as DC and Baltimore during December , normally correlates to a decent snow season. Works many times, of course there are exceptions.  

Also, you will hear how things just are not syncing up like they use to. Some signals you look at would have you assume winter will be normal, but then the pattern head fakes and we go very warm.  

 

So I think I may have asked this before, but...overall...is modeling getting more volatile now? (I know it wasn't what you'd call "stable" before, lol) From here on, are we going to see less consistency? And are things going to overall start behaving in ways different than before? (And on that subject...I'm wondering if analogs are gonna become more and more useless!)

[Ralph Wiggum]

Ridge bridge type thang on the EPS:

[Ralph Wiggum]

^^

neutral/positive PNA...check

EPO ridge...check

Ridging into Greenland...check

Ridge poking into AO region...check

Trof digging in the OV...check

Weak quasi 50/50 low...check

I can live with this potential.

[CAPE]

5 minutes ago, Ralph Wiggum said:

^^

neutral/positive PNA...check

EPO ridge...check

Ridging into Greenland...check

Ridge poking into AO region...check

Trof digging in the OV...check

Weak quasi 50/50 low...check

I can live with this potential.

It's the same result as the previous run. Where is the potential? Pretty cold. And pretty dry. And no snow. If that time frame is not going to produce, which at this point it appears it wont, who cares if h5 looks a bit "prettier" this run than last.

[showmethesnow]

2 hours ago, frd said:

Great update,  I hope we eventually see  some positive signs in the HL.  Seeing some +4 to +5 AO ensemble members is a bit worrisome, and the recent 4 day trends continues more so positive. 

Noticing these huge bowling bowls moving across the country with that fast Pac jet is reminiscent of last winter to a degree. Alaska is set to record a fast Pac jet up there this early week.  

Another thing to watch, and I believe there is a statistical correlation here to our area from DC North is that having a + PNA in December is key to accumulating snowfall. Maybe more so than a -AO.  That relationship probably changes in January. So difficult lately getting the PNA to go + and remaining so.    

I love to see the Pac and the HL align down the road.  If you go HM's route there is hope in December.   

Couple of things here in regards to the AO state. As I have said quite often I am not a big fan of just looking at the indice values as quite often they don't tell the whole story. So over recent years I have focused on the physical look on the maps to get an idea of the different indices. I also am not a big fan of following surface pressures especially at longer leads because they quite often fluctuate wildly run to run. So I pretty much focus on the 500's where you typically see much less variance run over run and are more likely to being closer to correct then the surface representation over the longer leads. So what I am saying is when I am trying to get a feel for the AO state I am actually looking at the physical representation at 500 mbs unlike where the indice values are produced at the surface just from pressures at different latitudes. Admittedly the current surface representation at the end of the extended is pretty drastic but when I am looking at 500's they are not representative of what I consider an AO at +++SD.  At least a +++AO that looks to have any staying power whatsoever. It's a look I would associate with a somewhat strong AO but nothing to the degree we are seeing on the indices. The look also is one of a possibly weakening AO towards the end of the extended but that is still somewhat up for debate in my mind.

I don't believe it is any coincidence we are seeing the AO go strongly positive just as as we are seeing the 500 mb PV, or portion of it, makes its move over the pole towards our side of the globe. I think rightly or wrongly the computers are thinking the natural response to this in the current setup is to plant a big Blue Ball of death underneath this pv while it is moving over the pole and leaving it there. Now I just spent 10 minutes trying to write out my my thinking as to why they may be doing this and why they could potentially be wrong and after rereading it it didn't make any sense so I deleted it. So what I am trying to say is, I am not so sure I believe them and I have no good way of explaining my reasonings for that. 

Two other things. Typically in a +AO we see a colder Strat above it, the stronger the AO the colder the temps. What we are seeing is the exact opposite projected. We are talking extreme warming occurring at the same time we are seeing the AO pop. Also looking at the 10 hPa 60* zonal winds we are seeing the exact opposite of what we would expect. In a stronger AO state we typical see stronger zonal winds and again the stronger the AO the stronger the winds. Yet what we are seeing with the GEFS and the CFS is that after a brief spike (once again occurring with the pv move over the pole) where winds reach avg to slightly below avg we are seeing a very significant dip in wind speeds. 

The models could very well be spot on with the projected +++AO, I won't deny that. But there are too many things that I am seeing that run contrary to a typical strong AO. They just don't add up. So what we are possibly looking at here is nothing more then the boogieman in the closet scaring us that we come to find out never did exist.

[WxUSAF]

26 minutes ago, C.A.P.E. said:

@showmethesnow

Not bad. Nice EPO ridge building, and the NAO looks...neutral.

 

EPS has looked better than the GEFS for the last 2-3 runs past D10.  I don't hate that.  

3 minutes ago, C.A.P.E. said:

It's the same result as the previous run. Where is the potential? Pretty cold. And pretty dry. And no snow. If that time frame is not going to produce, which at this point it appears it wont, who cares if h5 looks a bit "prettier" this run than last.

The Dec 1-2 storm looks like it will suck the oxygen out of the room so to speak for a couple days beyond.  That makes that trough go more N-S oriented and prevents any follow-on s/w from amplifying out of the southwest.  So we might need to wait for the flow to relax a little (barring a clipper in the 3rd-5th timeframe) around the 8th.  Then of course it's a question of cold air availability, but getting snow is always a wackamole of issues.

[Ralph Wiggum]

12 minutes ago, C.A.P.E. said:

It's the same result as the previous run. Where is the potential? Pretty cold. And pretty dry. And no snow. If that time frame is not going to produce, which at this point it appears it wont, who cares if h5 looks a bit "prettier" this run than last.

Because a "prettier" look could translate into better teleconnections down the road. Would you rather it see it headed the opposite direction or trending to the good?

[CAPE]

Just now, WxUSAF said:

EPS has looked better than the GEFS for the last 2-3 runs past D10.  I don't hate that.  

The Dec 1-2 storm looks like it will suck the oxygen out of the room so to speak for a couple days beyond.  That makes that trough go more N-S oriented and prevents any follow-on s/w from amplifying out of the southwest.  So we might need to wait for the flow to relax a little (barring a clipper in the 3rd-5th timeframe) around the 8th.  Then of course it's a question of cold air availability, but getting snow is always a wackamole of issues.

I wanted to put a TY, a , and a , on this post, but ofc it wasn't possible.

[WxUSAF]

7 minutes ago, C.A.P.E. said:

I wanted to put a TY, a , and a , on this post, but ofc it wasn't possible.

 We are not going to know anything about storm chances after next weekend for a while, in my opinion. Whether it’s a clipper or something larger the following weekend. Because next weekends storm will have so much control over the flow afterwards. So focusing on next weekend is probably the safe bet for now. I think what we want to root for is something like the Canadian showed today, with a more significant piece of energy Moving out ahead of the main storm. If it could move to our south it could give us a light event and also help drag the boundary further south for the larger storm which would give us a better chance of more front end freezing or frozen precipitation.

[Bob Chill]

EPS isn't that scary. Trough near HI is a general connection with a +pna. Workable. Ultimately I'd like to see the ao not give up like the redskin's secondary. I've never expected deep winter to lock in early Dec with all cylinders firing and vsst majority of our snow events are flawed. Big ones have common needs but smaller events pop out of nearly all partially flawed patterns. 

I'm bringing up the AO concerns because that's the king of decent snow events and also a teleconnection that can be modeled fairly well at longer leads. 

[CAPE]

1 minute ago, WxUSAF said:

 We are not going to know anything about storm chances after next weekend for a while, in my opinion. Whether it’s a clipper or something larger the following weekend. Because next weekends storm will have so much control over the flow afterwards. So focusing on next weekend is probably the safe bet for now. I think what we want to root for is something like the Canadian showed today, with a more significant piece of energy Moving out ahead of the main storm. If it could move to our south it could give us a light event and also help drag the boundary further south for the larger storm which would give us a better chance of more front end freezing or frozen precipitation.

Yeah I still think the threat centered on Dec 2 is pretty low probability for our region, but not a total lost cause. I keep thinking the better shot at something tracking underneath and producing a frozen event is NS energy dropping in a few days later, not that that is very likely either.

[CAPE]

6 minutes ago, Bob Chill said:

EPS isn't that scary. Trough near HI is a general connection with a +pna. Workable. Ultimately I'd like to see the ao not give up like the redskin's secondary. I've never expected deep winter to lock in early Dec with all cylinders firing and vsst majority of our snow events are flawed. Big ones have common needs but smaller events pop out of nearly all partially flawed patterns. 

I'm bringing up the AO concerns because that's the king of decent snow events and also a teleconnection that can be modeled fairly well at longer leads. 

I see your concerns and ofc we all know(I think) how important the AO is for above normal snow chances in the general DC area. Outside of having a +AO with  sustained ridging in the EPO/WPO domains and a ton of luck, it's pretty difficult to overcome if it ends up a persistent feature during winter.

[showmethesnow]

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

GEFS has the upper strat on fire heading towards the end of the first week of Dec, and if that verifies there should be some impacts down the road on the troposphere. So I guess what I am saying is...SWE will save us from a prolonged ++AO.

Don't tell me you just went there? 

You of all people should know SWEs should never be mentioned until at least January and only as a last resort. Wonder how many people you just triggered and now are piling into the panic room. 

[CAPE]

Just now, showmethesnow said:

Don't tell me you just went there? 

You of all people should know SWEs should never be mentioned until at least January and only as a last resort. Wonder how many people you just triggered and now they are piling into the panic room. 

Shhh. My trolling is very subtle. 

[cbmclean]

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

Shhh. My trolling is very subtle. 

I wait until some one pulls out the recurving typhoon before I cliff jump./

[Bob Chill]

This is like the opposite of model porn. I can't recall ever seeing the AO this positive before. Lol

 

 

[Bob Chill]

3 minutes ago, Rtd208 said:

Break out the shorts and suntan lotion.

Being totally honest... if we're going to have a shutout pattern then bring on warm and dry. Mountain biking and hiking are good therapy for crap patterns. 

Unless we see some drastic changes over the next week looks like a warm period is on the way. Hopefully it's just temporary. 

[nj2va]

If the AO is forecasted to be so abnormally +, question for the pros...why do we have this map?  Slightly +PNA driving that? 

[Mr. Kevin]

I'm probably wrong about this, but I've heard this before that when the ao goes strongly positive that it usually means a SSW is underway and possibly changes down the road. It reaches a very positive state and plummets from there. Color me crazy, but its been a while since i heard that.

[cbmclean]

1 hour ago, nj2va said:

If the AO is forecasted to be so abnormally +, question for the pros...why do we have this map?  Slightly +PNA driving that? 

That is truly fascination, how in the world could that 2m anomaly map coincide with that H5 look, unless the GEFS ensemble mean is way different than the OP?

[jaydreb]

0z GFS comes close to giving us our 12/5 snow.  This time period still bears watching (before we break out the flip flops shorts).  

[Maestrobjwa]

15 minutes ago, jaydreb said:

0z GFS comes close to giving us our 12/5 snow.  This time period still bears watching (before we break out the flip flops shorts).  

Wait a minute...How are we back on that exact date as our snow miss (and subsequent warm-up) last year? Can someone please turn off the atmospheric tape recorder? Lol (different setup, I know...but I'm wondering if the result repeats itself just to troll us, lol)

[CAPE]

EPS has been muting the +AO/NAO look in recent runs, and is now suggesting it will indeed be short lived.  Showmethesnow highlighted this in his write up yesterday morning. And just like that, we have this advertised look 10 days into December.

[showmethesnow]

Just a few small changes on the overnight EPS. Good ones @MDstorm so you can keep reading the post. Maybe they will get some to back off the ledge... until the next run. 

As I mentioned yesterday for various reasons I look at 500's to get a read on the AO state on the surface. I find the 500's tend to give me a more accurate read on what to expect then just looking at surface pressures especially when we are beyond the short and mid ranges (7+ days out).

Now admittedly I cringed a little when I got a chance to look over the mid day runs early yesterday evening. Spent some time earlier in the day trying to calm some fears only to come across this. Not what I really wanted to see. Consolidated PV where the EPS was now downplaying the possibility of a portion of the pv migrating over to our side which I feel is key. The only positives I see here, if you want to call them that, are the fact that the pv is displaced a little bit off the pole, the stronger neg anomalies are not centered over the pv and that we aren't seeing extreme neg departures with those anomalies. To me this look suggests a strong 2 or even possibly a 3 SD +AO. Now we have had some projected 4/5 SD +AO thrown out over the last few days. This look isn't close and I have yet to see a look that comes close over these last few days. Believe me, when you see it you will know it. A huge deep purple blob and circular pv located squarely over the pole. It is a look that has left me whimpering, lying on the floor in a fetal position on occasion over the years.

 

 

Okay now lets look at the overnight run. Notice some changes? We are now seeing the ridging into Greenland I had mentioned the possibility of yesterday. The EPO is once again there. We are seeing height builds up to and over the pole. The EPS is once again hitting on a piece of pv rotating over to our side and now is throwing in one over towards the Aleutians as well. Note also that the neg anomalies are now situated off of the pvs to their south. This look here suggests to me that we would see a nuetralish looking AO on the surface.

 

 

Let's look at the surface of the above. Yesterday 12 Z is looking pretty rough. Lower pressures are consolidated and located squarely under the PV depicted at 500's. Only somewhat saving grace is that are displaced off the pole somewhat. And when you look at the AO index we are seeing 2 SD that is suggested from the 500's.

 

Now look at the latest run. We now are seeing a split of the low pressure anomalies with the departures not as strong as the previous. Just eyeballing this I would say this is probably a weak positive. Looking at the index though has this as a weak neg. Looking at the AO progression we see a brief spike (3/4 days) to a +3 SD before it drops again into the -AO category.  And I think this spike is the result of the migration over the pole of a piece of PV.

 

 

One other thing I would like to show. Notice the configuration of the pv and where the pieces of  the pv are located as well as the ridging shaping it?

 

Now look at what had believed was a rough idea of a possibility yesterday knowing the tendencies/ bias' of the models so far this year as well what the tendencies with actual verification were. Not too shabby. We are seeing the EPO ridging as well as the Greenland ridging. Seeing a portion of the pv on the other side of the globe. Even seeing a piece of the PV towards the Aleutians that I thought was possible. The one thing we aren't seeing as of yet is the pv dropping much farther south that I believe is a possibility.

 

 

[CAPE]

The 0z GEFS also has a notable lack of blue up top at the end of its run, with hints of ridging building back into the NAO space.

[showmethesnow]

6 minutes ago, C.A.P.E. said:

The 0z GEFS also has a notable lack of blue up top at the end of its run, with hints of ridging building back into the NAO space.

Like the EPS better but at the very end of the GEFS is very promising.

eta: In regards to the AO/NAO. Haven't really looked into other areas as of yet.