October/November 2019 Mid/Long Range

[CAPE]

Hopefully that barely existent wave on the front ends up a bit more robust, and things fill in a bit. 1-2"?

[fourseasons]

On 11/8/2019 at 3:03 PM, LurkerBoy said:

None of you know what you’re talking about and there’s no women in this forum anywhere because it’s a boys club where outsiders are condescended to. Have a good winter. Move north

Guess this woman needs to move back to where she grew up:  Canada.

[Cobalt]

NAM does NAM things. Too bad it's in clown range. 

[NorthArlington101]

NAM does NAM things. Too bad it's in clown range. 

fringed

[Wonderdog]

1 hour ago, Cobalt said:

NAM does NAM things. Too bad it's in clown range. 

Don't worry. There is plenty of snow holes in southern Virginia that will no doubt move north.

[CAPE]

Looks a tad Nino-ish. 

I like the look up top, and the -heights over the Aleutians. Could be a really nice h5 pattern rolling this forward as we edge closer to Dec.

[BristowWx]

1 hour ago, C.A.P.E. said:

Looks a tad Nino-ish. 

I like the look up top, and the -heights over the Aleutians. Could be a really nice h5 pattern rolling this forward as we edge closer to Dec.

That’s what you want to see if you don’t want to turn on the AC at Thanksgiving.  

[showmethesnow]

1 hour ago, C.A.P.E. said:

Looks a tad Nino-ish. 

I like the look up top, and the -heights over the Aleutians. Could be a really nice h5 pattern rolling this forward as we edge closer to Dec.

Playing with fire with the pv migrating over towards Alaska like that. You can already see the cold getting bottled up on the other side of the globe as N America gets flooded with PAC air and warmth. With the trough/east/ridge/west setup we would get the occasional shot of seasonal/slightly below cold from Canada but at this time of year that won't cut it.

[CAPE]

21 minutes ago, showmethesnow said:

Playing with fire with the pv migrating over towards Alaska like that. You can already see the cold getting bottled up on the other side of the globe as N America gets flooded with PAC air and warmth. With the trough/east/ridge/west setup we would get the occasional shot of seasonal/slightly below cold from Canada but at this time of year that won't cut it.

Dude we are always playing with fire one way or another here south of 40N loI. I would take my chances with that look, esp given it looks like heights are building into the NAO domain.

[osfan24]

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

Somebody give me a weenie like.

Even the models recognize the DC snow hole in November. Impressive. Usually takes us much farther into the winter before seeing this kind of map.

[CAPE]

2 hours ago, showmethesnow said:

Playing with fire with the pv migrating over towards Alaska like that. You can already see the cold getting bottled up on the other side of the globe as N America gets flooded with PAC air and warmth. With the trough/east/ridge/west setup we would get the occasional shot of seasonal/slightly below cold from Canada but at this time of year that won't cut it.

If the EPS is correct, we lose the big WPO ridge and the -EPO for a time, and with that we lose the mechanism for cross polar flow. I don't see a flood of Pacific air as much as the cold air source we have had being cut off for a time. There is still a PNA ridge out west in a favorable location, and we are seeing indications of ridging in the NA. Now if the PNA goes negative and we don't see positive heights continue building into the NAO space, then there will be a definite warm up, but not like that is entirely unexpected at this point. If the Pacific is going to "betray" us in the long term, we in trouble going forward any way you slice it.

[CAPE]

0z 12k NAM has 1-2" of snow for the eastern shore late Tuesday, maybe pushing 3 in S DE and down near SBY lol.

Defo deserving of....

 

 

 

 

 

[WinterWxLuvr]

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

0z 12k NAM has 1-2" of snow for the eastern shore late Tuesday, maybe pushing 3 in S DE and down near SBY lol.

Defo deserving of....

 

 

 

 

 

Probably show a nor’easter next run. 

[frd]

Soon we will know how smart the seasonal models are with the NAO call. The post by Tony is interesting. 

Of note, if you click and close up on the image I do tend to see what Isotherm  mentioned and someone else at 33andrain, a deeper NAO after the bottom of the solar min. 

Also, not related to this post by Tony , but read as well,  next winter we reap the benefits of an established Easterly  QBO .  Personally I have seen the cycles go slower and then other times quicker. DT has something online that when the QBO is  -10 to -20 it corresponds to a very cold Eastern winter. As Isotherm mentioned as well we are not dropping fast enough to reap the benefits of the changing QBO in the early winter , but will tend to at least increase the odds it helps us when we get to Feb and March 

    

 

 

[CAPE]

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

Hopefully that barely existent wave on the front ends up a bit more robust, and things fill in a bit. 1-2"?

Well, looks like it's getting there...

[Solution Man]

That's great, considering where we've come from. Bit of mood flakes as we move towards December. 

[showmethesnow]

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

Well, looks like it's getting there...

Fringed. 

That's alright. I will gladly give up these nickle/dimers to you snow starved shore men just as long as I get in on the death bands from all the N'easters we are going to get this year. 

[CAPE]

I like where the advertised pattern is heading in general towards the end of the month. It will become a bit milder for a time. Guidance indicates continued disruptions of the SPV, with some warming and height rises. Just need to keep the SPV on the weak side- a SSWE is not required for a good response in the HL troposphere to allow cold air delivery into the midlatitudes. Looking at the teleconnections on the EPS, AO stays slightly negative, NAO trends negative, and this is clearly seen at h5 on both the EPS and GEFS in the LR with heights building across Greenland into Baffin. We shall see if it materializes. The PNA trends neutral, and WPO/EPO positive. So it looks like while we lose the big coupled blocking ridge out west, we will see improvement in the NA, hopefully in the form of a legit -NAO (blocking ridge) towards the end of the month. I don't think the PAC is going to turn hostile- this looks to be more of a relaxation. Ofc time will tell, lol.

 

[CAPE]

1 minute ago, showmethesnow said:

Fringed. 

That's alright. I will gladly give up these nickle/dimers to you snow starved shore men just as long as I get in on the death bands from all the N'easters we are going to get this year. 

I would be surprised to see anything on the ground. Have seen this hundreds of times on guidance, and it almost never materializes. Cold chasing rain. Seeing some flakes fly would be a win.

[osfan24]

1 hour ago, C.A.P.E. said:

I would be surprised to see anything on the ground. Have seen this hundreds of times on guidance, and it almost never materializes. Cold chasing rain. Seeing some flakes fly would be a win.

I'm definitely not expecting to see anything on the ground, or maybe even anything elevated. I'd just like to see significant accumulations on the map because it assures we will see a period of snow falling from the sky.

[CAPE]

@showmethesnow

I see your concern about the lower heights near Bering Strait/Chukchi, but I am not too worried at this point as there is still some ridging over western Canada, and it seems this may be part of a pattern relax/reload. Now if we see those heights persist and lower, and we end up with a blue ball migrating towards the GOA, then there might be a problem. Looking at the strat panels on the Euro, the PV gets elongated but there is still a piece on our side. Verbatim on the EPS, surface temps are average to slightly above from the 20th to the 25th in the east, but if the developments in the NA are real, and the EPAC doesn't further deteriorate, we should see lower heights develop in the eastern US on future ens runs in response.

[CAPE]

11 minutes ago, osfan24 said:

I'm definitely not expecting to see anything on the ground, or maybe even anything elevated. I'd just like to see significant accumulations on the map because it assures we will see a period of snow falling from the sky.

Yeah that's a good way to look at it. My forecast has rain ending as snow, little or no accumulation.

[aldie 22]

NAM seems a bit juicy here, I'll take my snowtv/mulch crust and run with it.

[showmethesnow]

Whether right or wrong the ensembles are advertising a mostly CONUS wide warm up as we head into the extended and somewhat beyond.

Below we have the EPS (GEFS has some slight differences but generally has the same idea). What will induce this warm up is the PV that has generally been located around the Hudson Bay region will migrate westward towards Alaska/NE Russia. This effectively cuts off cross polar flow which has been sending and will send much colder air relative to norms into our region. With the withdrawal of the pv in central/eastern Canada we are also seeing the amplified troughing in the mid-west/east flattening as well. Part of the reason we were seeing good ridging in the west was due to the backing of the flow that was being induce but the amplified troughing in the east. Take that strong troughing out and we lose that backing and so correspondingly we see the western ridging breakdown as the PAC flow overwhelms it as seen below. Now we do still see an extreme northern based +PNA but it does us little good. What is happening is that the PAC Flow is overwhelming the CONUS effectively putting up a wall against the N Stream which is flowing around the extreme northern ridging.

 

 

Now below we have the response in temps to this setup. Notice we have basically warmth through the whole of N America at the end of the extended (We do see below norm temps in the SW which are the product of weakness/troughing we see in that region.). As we can see, the N Stream is flowing off the N PAC around the troughing setup by the PV. With coming off the PAC these temps are moderated somewhat so they are showing as warm anomalies through Canada but they would be more then sufficient for our needs if they decided to give us a visit. Unfortunately there is no vehicle to deliver them. The extreme N based ridging comes no where near to providing the oomph to bust through the PAC flow that has setup through the CONUS. And the eastern trough that could have served us as well? That has become muted as well with the pv withdrawal. So the core of the colder air is basically locked up into Canada.  Now as far as our region what we could probably expect with this setup is longer periods of warmth with brief intrusions of seasonal to slightly below temps as cold fronts would slide down into the Mid-west and slide eastward as they work around the very weak troughing we see through the region. The cold provided would most likely not be sufficient for our needs (snow) as we are still very early in the season. Now this doesn't take into account an extreme event that can manufacture its own cold (Bombing low, Bowling bowl across the south). So there is always that.

 

Now I know there are some in here who will panic. I wouldn't. This will more then likely be a somewhat brief warmup (2 weeks maybe 3) as there are already signs of this look breaking down at the end of the extended. And we couldn't have asked for better timing as well as this early in the season we struggle mightily anyway (better then handicapping the temps during the heart of winter). This will also be a good test to see if the period we have seen recently is actually the base state (+PNA, -EPO, eastern troughing) that we can expect through the CONUS for at least the first half of winter, which in my mind would be a winner. And some of what I am seeing suggests to me that the models may in fact be beginning the process of reverting to this. 

There are actually quite a few things I like seeing even while we may be experiencing this relax. The stratpv is actually getting hammered. This pretty much coincides with the CFS projections that it has had for several weeks and what the GEFS has been advertising recently. Also we are seeing quite a disconnect from the 10mb pv down to the 500mb one. Another sign that the pv is under extreme duress. Still want to see a few more days of runs but the evolution I believe we are over/around the pole beyond the extended is one that will actually feature some great blocking (think big red ball) with a correspondingly strong -AO. As far as the NAO domain I am starting to lean fairly strongly on that becoming a player as well (I favor an eastern based one at this time). Let's see what the next week or so of runs give us and whether the current projections are somewhat accurate. If they are, we could be setting up for a very favorable look come mid-December.

[Rhino16]

4 minutes ago, showmethesnow said:

This will more then likely be a somewhat brief warmup (2 weeks maybe 3) as there are already signs of this look breaking down at the end of the extended.

Good writeup. Maybe we’ll be able to spend turkey day outside and not be cold the whole time.

[showmethesnow]

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

I would be surprised to see anything on the ground. Have seen this hundreds of times on guidance, and it almost never materializes. Cold chasing rain. Seeing some flakes fly would be a win.

To say I am less then enthused about the prospects at this time, especially west of the bay would be an understatement. As the snow maps suggest I believe the best chances for anything of substance will be confined to the eastern/southern portions of MD and NE Va as we do see a slug of moisture riding up from the south just in time to enhance moisture into the frontal passage. Up in my neck of the woods I think we are looking at instability snow and/or rain showers at best as the 500's swing through with very little to nothing with the frontal passage. And I am not really impressed with the 500's at this time but will reserve judgment until we get within 48-72 hours as the models should pick up by then on any possible energy rotating through. 

[showmethesnow]

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

I like where the advertised pattern is heading in general towards the end of the month. It will become a bit milder for a time. Guidance indicates continued disruptions of the SPV, with some warming and height rises. Just need to keep the SPV on the weak side- a SSWE is not required for a good response in the HL troposphere to allow cold air delivery into the midlatitudes. Looking at the teleconnections on the EPS, AO stays slightly negative, NAO trends negative, and this is clearly seen at h5 on both the EPS and GEFS in the LR with heights building across Greenland into Baffin. We shall see if it materializes. The PNA trends neutral, and WPO/EPO positive. So it looks like while we lose the big coupled blocking ridge out west, we will see improvement in the NA, hopefully in the form of a legit -NAO (blocking ridge) towards the end of the month. I don't think the PAC is going to turn hostile- this looks to be more of a relaxation. Ofc time will tell, lol.

 

 

Great minds think alike. Of course it doesn't hurt that if I am wrong at least I have a fellow shipmate to go down on the Titanic with me. 

Pretty much agree with everything you are saying except differ somewhat on what the models suggest in regards to the AO (or at least I believe we see a much more robust signal). Looking at the mid and upper levels is suggestive to me that we see some fairly impressive height builds over the pole and polar regions (2-3 weeks). These same things are also suggestive of major fracturing and displacement southward of the pv at 500's, aka strong -ao.

[CAPE]

0z Euro SPV currently, and at the end of the run. It is forecast to undergo continued perturbation from the periphery, ending up with 2 main areas of lower heights.The area of lowest negative height anomalies ends up a bit further north than the current location, but much less consolidated/significantly weaker. 

 

[frd]

The more I visit this site the more I love it , plus Simon updated the site with this new data, which I have not seen anywhere else  ( lower stratospheric anomalies ) :

 

New product online at https://simonleewx.com/polar-vortex-forecasts/… GEFS forecasts of tercile anomaly categories of 100 hPa 60°N zonal-mean zonal wind. These lower stratospheric anomalies are important for influencing the what happens in troposphere, and are often more relevant than 10 hPa.

 

 

Polar Vortex Forecasts

All charts are updated once daily between 8:30-10:30 AM London time. Please feel free to share any images from this site on social media or elsewhere.

00Z GFS 0.5° & GEFS 1.0° 10 hPa 60°N ensemble plume 

00Z GFS 0.5° 10 hPa 60°N forecast evolution

White crosses indicate a strong vortex event (>41.2 m/s) following Tripathi et al. 2015.

CFSv2 1.0° 10 hPa 60°N bias-corrected ensemble plume

This is produced by taking the 4-member ensembles from 00, 06, 12 and 18Z yesterday and combining into a 16-member ensemble, out to 45 days. The bias is calculated as the difference between the 1999-2009 hindcasts (available from the S2S database) and ERA-Interim reanalysis. The CFSv2 has a significant bias toward a weak vortex, especially for forecasts launched in early winter, so accounting for this drift is necessary.

It should be noted that a simple linear bias correction does not necessarily solve the problems produced by the bias, as the bias can interfere with the model dynamics.

00Z GFS 0.5° & GEFS 1.0° 1000 hPa Northern Annular Mode (NAM) ensemble plume

This is calculated using the method of Gerber and Martineau (2018) using standardized anomalies of 65-90°N geopotential height (with respect to 1979-2018 ERA-Interim climatology) with the global mean anomaly removed. I thank Zac Lawrence for calculating the filtered ERA-Interim climatology used here.

00Z GEFS 1.0° 100 hPa 60°N tercile categories

The tercile-category anomaly of the lower-stratospheric polar vortex, defined by the 100 hPa 60°N zonal-mean zonal wind, has been used as a diagnostic for the behaviour in the ‘coupling layer’ between the stratosphere and troposphere, i.e. the level in the stratosphere where circulation anomalies are important for influencing tropospheric weather regimes (e.g. Charlton-Perez et al. 2018, Lee et al. in review). The chart below shows the percent of GEFS members in each tercile anomaly category, based on daily 1979-2018 ERA-5 climatology.

00Z GFS 0.5° & GEFS 1.0° Scandinavia-Greenland dipole ensemble plume

This dipole pattern, defined in Lee et al. (2019) as the MSLP difference between a grid box over Scandinavia and a grid box over north-east Greenland, can be used as a diagnostic of anticyclonic wave breaking in the north-east Atlantic which can enhance vertically-propagating wave activity and weaken the stratospheric polar vortex. In the paper, we use 40 hPa as a threshold (strong Scandinavia high + deep Greenland low) as this is similar to what occurred before the February 2018 major SSW, but values above 30 hPa are noteworthy.

 

 

 

[CAPE]

33 minutes ago, showmethesnow said:

To say I am less then enthused about the prospects at this time, especially west of the bay would be an understatement. As the snow maps suggest I believe the best chances for anything of substance will be confined to the eastern/southern portions of MD and NE Va as we do see a slug of moisture riding up from the south just in time to enhance moisture into the frontal passage. Up in my neck of the woods I think we are looking at instability snow and/or rain showers at best as the 500's swing through with very little to nothing with the frontal passage. And I am not really impressed with the 500's at this time but will reserve judgment until we get within 48-72 hours as the models should pick up by then on any possible energy rotating through. 

This is where I am with it. If there is to be an area of light accumulations at the tail end, it will probably, oddly enough, be to my east/SE. I think most of us have a shot as seeing snow in the air, whether from the weak wave or instability flurries as the cold moves in.