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December 2022 Medium-Long Range Disco


WxUSAF
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Time for your famous - "We are too far north, south or east for good snows" quote! (Maybe the east is not in that!)
 
Oh yea

Too North for southern sliders
Too south for miller bs or just winter weather in general lol
Too west for nina coastals(congrats cape)
Too east for clippes
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15 minutes ago, BristowWx said:

If you think that is bad the next one is a heart breaker…wall of high pressure in Canada and we go to rain on Xmas eve

 

13 minutes ago, Ji said:
15 minutes ago, BristowWx said:
If you think that is bad the next one is a heart breaker…wall of high pressure in Canada and we go to rain on Xmas eve

Storm covers like 70% of country. We suck

Why are you all doing this to yourselves? Like real talk...help me understand...Why torture yourselves with OP runs at D8+??

 

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23 minutes ago, Ji said:
37 minutes ago, Maestrobjwa said:
Why are you all doing this to yourselves? Like real talk...help me understand...Why torture yourselves with OP runs at D8+??
 

Because non snow always verifies

Not always. And when it does...why you torturing yourself 300+ hrs ahead of time? And then when we DO get snow, you're still not satisfied, lol So again...why do you torture yourself?

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0z GEFS depicts a pretty favorable window for snowfall from the 20th-24th. Seems to be a few members that followed the OP which would explain some of the greater westward totals, so definitely not as much of a sign of suppression on these panels.

gfs-ensemble-all-avg-east-snow_96hr_inch-1948000.thumb.png.615cc2762ad52f37acbfb1eeae07b260.png

gfs-ensemble-all-avg-east-qpf_anom_5day-1948000.thumb.png.d513bfd201a7db7c7e5786576397916b.png

What I like to see is the appearance of a low pressure system in the 50/50 region as per the GEFS mean, it looks like that's been picked up on the recent ensemble runs.

gfs-ensemble-all-avg-namer-mslp_anom-1753600.thumb.png.da40fd2555034807de765390b02b9f4b.png

PNA begins to spike during this timeframe as well, so the teleconnections definitely bode well for a train of systems during the week leading up to and after Christmas. 

 

EPS quite likes an idea of a 22nd-24th event as well. +PNA popping and -AO nearing -5 would make me somewhat hopeful for this window. 

ecmwf-ensemble-avg-east-mslp_with_low_locs-1775200.thumb.png.ad2195a9a353c015b9783fade0429abc.png

ecmwf-ensemble-avg-conus-t850_anom_stream-1753600.thumb.png.6f4a8bdaeec36c4265217ef637c735c4.png

ecmwf-ensemble-avg-conus-z500_anom-1775200.thumb.png.5763c38d191b50583bf2893cf5d8db84.png

 

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The first chance of something trackable is early/mid next week as the trough digs underneath the sprawling Upper ridging across Canada. A wave off the Pacific takes the southern route underneath the PNA ridge. A lot of ways this could play out depending on the timing/location of the main features, but there is a path for a modest event. Here is the wave on the GEFS-

1671483600-LrgrVgrfmCA.png

The location/timing/orientation of the trough allows the wave to stay more intact on the GEFS depiction with a chance it can gain some latitude as the trough initially digs a bit more westward. Euro/EPS shears it out under the NS vortex.

1671645600-AdjkFShpAfg.png

Beyond that it still looks something more significant may transpire around Christmas.

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28 minutes ago, WxUSAF said:

For perspective, the last -20F or greater wintertime (DJFM) departure at BWI was Jan 31, 2019. We've had MANY +20F days in DJFM since then. 

Why does it appear on the extended models that each potential event or low pressure system seems to scoot along fairly quick?  I thought, perhaps in error, that the blocking causes systems to slow down and amplify.  The system at hour 252 on GFS, for example, just keeps on trucking through seemingly plowing through strong highs to the north. 

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24 minutes ago, BristowWx said:

Why does it appear on the extended models that each potential event or low pressure system seems to scoot along fairly quick?  I thought, perhaps in error, that the blocking causes systems to slow down and amplify.  The system at hour 252 on GFS, for example, just keeps on trucking through seemingly plowing through strong highs to the north. 

Having a -NAO does not always equal a block.  A true sustained block in the atmosphere at h5 features a persistent dipole(upper low and high, ideally cutoff from the main flow). My more practical gauge is to see how lows(upper level vortices) behave as they progress eastward into the 50-50 region. If they essentially zoom through there and up into the NA, that's not a block imo. Not to say that situation isn't useful, but it is more indicative of a progressive flow and timing is critical.

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3 minutes ago, CAPE said:

Having a -NAO does not always equal a block.  A true sustained block in the atmosphere at h5 features a persistent dipole(upper low and high, ideally cutoff from the main flow). My more practical gauge is to see how lows(upper level vortices) behave as they progress eastward into the 50-50 region. If they essentially zoom through there and up into the NA, that's not a block imo. Not to say that situation isn't useful, but it still is more of a progressive flow and timing is critical.

thanks that makes sense.  the term blocking is thrown around a lot...for the novice you hear blocking and think we are in business.  the best example of blocking, in my head, would be a long duration overrunning event where we are on the right side of it and it spits out frozen for days....that would be fun.  my point last night was we see some of these fantasy range  systems cutting into 1040-1050 highs without much resistance...at least on the long range models.  if we had true block with highs locked in over NE this would at least push back and lock the cold in longer. 

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The strongest indication for an event across guidance within our upcoming 'favorable window' is currently late next week into the weekend. As @Cobaltmentioned in his post, there is a pretty nice signal on the EPS. 

1671775200-OJxKAHizw14.png

CMC ens holds the main trough and core of the cold back a bit, with some ridging out in front, and indicates a more messy looking scenario with initial low tracking NW.  The timing is somewhat different.

1671710400-hpOTBgXoZx4.png

Weaker signal on the GEFS, but it is there, and it looks more like the EPS with a broader trough and initial colder air mass in place.

 

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39 minutes ago, BristowWx said:

thanks that makes sense.  the term blocking is thrown around a lot...for the novice you hear blocking and think we are in business.  the best example of blocking, in my head, would be a long duration overrunning event where we are on the right side of it and it spits out frozen for days....that would be fun.  my point last night was we see some of these fantasy range  systems cutting into 1040-1050 highs without much resistance...at least on the long range models.  if we had true block with highs locked in over NE this would at least push back and lock the cold in longer. 

Looking at H5, it looks like the "block" is oriented east/west as opposed to north/south which delays that primary lp from scooting away and allowing moisture to come up the coast after this upcoming event.

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26 minutes ago, WxUSAF said:

When it comes to arctic PVs phasing into giant storms, the Canadians should obviously be better equipped to model that :lol:

Considering the time range and all the noise between now and then that needs sorting out, the Gfs was pretty close to the same solution as the cmc.
 

Yea I get that for many here the fact one is wet and the other 2 feet of snow is lol but synoptically a slightly colder antecedent airmass in front, slightly less amplified primary, and the Gfs would have been the cmc solution. 

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Just now, psuhoffman said:

Considering the time range and all the noise between now and then that needs sorting out, the Gfs was pretty close to the same solution as the cmc.
 

Yea I get that for many here the face one is wet and the other 2 feet of snow is lol but synoptically a slightly colder antecedent airmass in front, slightly less amplified primary, and the Gfs would have been the cmc solution. 

Yup. For whatever reason, the last 24-36 hours of Op runs have often wanted to phase in the PV to this event. Ensembles want nothing of the sort. 

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10 minutes ago, mattie g said:

Methinks someone saw the 12z CMC.

This depiction is what I think might happen if a cold disturbance runs over ripe warm waters off the MA coast… then BOOM. 

Not saying we’ll get a foot right here in DC. But someone up the corridor towards the NE is going to get hammered within a few weeks of this pattern. 

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that system around the 23rd has been showing up on modeling for a while now, and it seems like the ensembles are beginning to parse the broad longwave features. with that said, there are actually a lot of pieces here, and they look like they can come together to produce some significant upside. at this point, it would be late December, and climo is much more favorable than it is now, even along the coast

  1. this is the highly anomalous ridge that is going to form as a result of the +EAMT that is going to take place over the next several days. notice how this ridge extends and cuts off into the Beaufort Sea. this is important because it both establishes a very cold antecedent airmass, and it displaces the TPV, which I'll get to in a bit
  2. this is the west-based -NAO blocking that forms as a result of this week's system. the Miller B that forms on Friday forces very warm air into the Davis Strait, which helps create a transient block that then decays over this region. this kind of decaying block over the Davis Strait is a precursor to some of our largest storms
  3. this is the TPV that has been displaced by the ridging I talked about earlier. this serves to deliver very cold air to the NE US ahead of the potential storm, and it also plays a very important role in establishing confluent flow over SE Canada... it could act as a kind of 50/50 ULL, which is also why the block is so important. both of them work in tandem to deliver HP to SE Canada and prevent a cutter 
  4. finally, this is the shortwave that is beginning to get picked out by modeling. this is a very vigorous signal for this far out, but it makes sense given the entire hemisphere forcing it into existence given the +EAMT and extension of the Pacific jet. this would roll off of the ridge and downstream into the confluent flow forced by the TPV and transient blocking

Untitled.png.bbeb12c3296f19ff01a43579059c9748.png

so, overall, there is a lot here to like. pretty much every piece is in place for a large-scale event around this time. now, there are obviously a lot of caveats at this range, as one would expect, and there is a possibility that something like the GFS OP plays out and it rains on everyone. I kind of have to favor inland regions, but that by no means rules anyone out

when I see this kind of longwave configuration, it does get me a bit excited. all of the pieces are in place, so we'll see how it plays out over the next week or so

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