Mid to Long Term Discussion 2017

[bhamwx205]

We actually need some ridging from the south so we don't go cold and dry. We are perfect right in the middle of the battleground. Some will win and some will lose. It's like that every year. So far so good.

agree 100 percent. That's why I don't understand the obsession with the PNA . What's modeled is far better as long as there is some Atlantic blocking even if it's just for a few days. - epo , +pna and no blocking out front leads to huge increase in a west track that would screw the carolinas. -epo with a little -NAO allows for nice overrunning or southern slider and won't allow a system a chance to amplify and will keep things more suppressed. if you look at the ensembles they depict just that. hardly any west tracks. so I'll take what's being modeled all day long.

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[Met1985]

6 minutes ago, bhamwx205 said:

agree 100 percent. That's why I don't understand the obsession with the PNA . What's modeled is far better as long as there is some Atlantic blocking even if it's just for a few days. - epo , +pna and no blocking out front leads to huge increase in a west track that would screw the carolinas. -epo with a little -NAO allows for nice overrunning or southern slider and won't allow a system a chance to amplify and will keep things more suppressed. if you look at the ensembles they depict just that. hardly any west tracks. so I'll take what's being modeled all day long.

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Yeah I agree. It's steps. Obviously some patterns look better than others but at this range it's about the H5.

[tnweathernut]

12 minutes ago, bhamwx205 said:

agree 100 percent. That's why I don't understand the obsession with the PNA . What's modeled is far better as long as there is some Atlantic blocking even if it's just for a few days. - epo , +pna and no blocking out front leads to huge increase in a west track that would screw the carolinas. -epo with a little -NAO allows for nice overrunning or southern slider and won't allow a system a chance to amplify and will keep things more suppressed. if you look at the ensembles they depict just that. hardly any west tracks. so I'll take what's being modeled all day long.

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The biggest caution is what has already been mentioned above by a few.  We need to keep a favorable NAO region with confluence under it in eastern Canada.  We are entering a time where trending in those areas will tell us a LOT about where this is headed.  I think it's fun to simply have something to watch...  Heck, it's not even January yet.  :-)

[Cheeznado]

FWIW about a third of the EPS ensemble members give a little snow to the north GA area on or around the 6th of Jan.

[Jon]

There's a few things I don't understand why folks are losing it over the 00z EPS. The -NAO isn't a true -NAO that would lead to any real sustained blocking, this has been seen on the means and a warmup is almost inevitable...so when people see the -NAO mean on the EPS go from -1 to neutral and freak out, I just don't get it. We're not in a predicted strong -NAO pattern, this is only a small microscopic block (if you want to call it that) that will largely have no influence in the current pattern. The pattern is driven by the -EPO and the -EPO alone. I told people to just watch the -EPO, that has been the index to watch this winter and we have a roaring one, as it's predicted to take a dive around New Years to -4.5 (00z EPS). The positive heights near greenland on the 12z isn't what would keep a storm from cutting, it's more or less the orientation of the -EPO ridge which largely determines how the confluence slides east and how far SE they slide. That and perfect timing with a s/w and energy. Anything that gets carried into that confluence will produce. We've seen fantasy storms already with this pattern and that won't stop with the "loss of the blocking over greenland"

Check out the orientation of the -EPO and the pacific overall on the 12z OP vs the 00z OP day 7-8

 

Do you see a difference in the orientation of the ridging in the PAC/-EPO? Best way to explain the difference is the 00z is more vertical, allowing the trough to dig south, then it spins east.

Now Day 10 on the 12z shows more blocking over greenland. 

But the new Day 9.5 has no ridge in the southern continental US, yet it's backing off of the blocking everyone is talking about losing over greenland...however, it's a better look. Broad trough with two cold centers instead of one largely located over the west like the 00z shows. Also notice the 540 line (red).

 

Now tell me why the weak -NAO matters.

[Jonathan]

10 minutes ago, Jon said:

Now tell me why the weak -NAO matters.

Thanks for making sense of it all, Jon. I would guess most of us not as knowledgeable as yourself always have "We need -NAO" beat into our brains so often that when we see one, then see it gone, instead of moving onto the other indices, we just freak over the NAO. Just a guess as to why there was some negativity about the weakening block in Greenland.

[Jon]

3 minutes ago, Jonathan said:

Thanks for making sense of it all, Jon. I would guess most of us not as knowledgeable as yourself always have "We need -NAO" beat into our brains so often that when we see one, then see it gone, instead of moving onto the other indices, we just freak over the NAO. Just a guess as to why there was some negativity about the weakening block in Greenland.

Don't mean to be condescending at all so if anyone took my post that way, that's just how it flows from my brain to my keyboard. We hardly ever get a true -NAO that really impacts our weather, it's best to run with another index. -EPO is hands down the one to watch for La Ninas, and the pattern coming up has that, and then some. I'd worry if we started losing that, or the troughing got centered west over time...the -EPO orientation alone could end up popping a SER, regardless of the atlantic.

[GaStorm]

1 minute ago, Jon said:

Don't mean to be condescending at all so if anyone took my post that way, that's just how it flows from my brain to my keyboard. We hardly ever get a true -NAO that really impacts our weather, it's best to run with another index. -EPO is hands down the one to watch for La Ninas, and the pattern coming up has that, and then some. I'd worry if we started losing that, or the troughing got centered west over time...the -EPO orientation alone could end up popping a SER, regardless of the atlantic.

The -EPO has been a much more dominant feature in the past few years but has not led to too much snow unfortunately. Not sure if the AO had anything to do with that as well since I remember it was mainly positive. If the AO stays negative maybe that could be enough to get the job done?

[griteater]

A few of the "Cold Rain" axioms are at play here...1) EPO cold is centered over the heartland, and 2) the eye of the needle gets tighter when you don't have certain features.  The GFS suite shows the perils in this pattern - i.e. EPO delivers the cold, but it's in and out, and the next system that approaches cuts.  Euro wants to bring out a wave soon after the cold moves in, and maximizes the limited timing window.  Who knows how that plays out, the 2 suites have some vast differences with the wave handling which are to be expected, but you need all the help you can get here to get a winter storm in terms of timing, transient NAO blocking, and SE Canada lows to help to suppress the storm track.

[packfan98]

There are so many variables in play in regards to a pattern. I think we tend to oversimplify things. The last time we had a raging negative NAO it was a good winter. We then put on the blinders and that's all we look for. It can (and has) snow without the -NAO. Thanks for the explanations Jon. You need to start making videos!

[packbacker]

13 minutes ago, Jon said:

Don't mean to be condescending at all so if anyone took my post that way, that's just how it flows from my brain to my keyboard. We hardly ever get a true -NAO that really impacts our weather, it's best to run with another index. -EPO is hands down the one to watch for La Ninas, and the pattern coming up has that, and then some. I'd worry if we started losing that, or the troughing got centered west over time...the -EPO orientation alone could end up popping a SER, regardless of the atlantic.

Jon - if we have a trough hanging off the west coast with a +NAO it won't be pretty.  Your showing a weaker NAO, transient or not, storm track won't be as suppressed as we need.  If the 12z run comes in weaker again with that feature we will see heights rise and storm track shift north.  

[tnweathernut]

3 minutes ago, griteater said:

A few of the "Cold Rain" axioms are at play here...1) EPO cold is centered over the heartland, and 2) the eye of the needle gets tighter when you don't have certain features.  The GFS suite shows the perils in this pattern - i.e. EPO delivers the cold, but it's in and out, and the next system that approaches cuts.  Euro wants to bring out a wave soon after the cold moves in, and maximizes the limited timing window.  Who knows how that plays out, the 2 suites have some vast differences with the wave handling which are to be expected, but you need all the help you can get here to get a winter storm in terms of timing, transient NAO blocking, and SE Canada lows to help to suppress the storm track.

I agree completely. Lots to iron out and all options are on the table.

IMO - The chances of a widespread southeast winter storm go down when no blocking (even if transient) and a SE Canadian low providing confluence isn't present - especially when the shortwave is coming from the southwest.

[Jon]

2 minutes ago, packbacker said:

Jon - if we have a trough hanging off the west coast with a +NAO it won't be pretty.  Your showing a weaker NAO, transient or not, storm track won't be as suppressed as we need.  If the 12z run comes in weaker again with that feature we will see heights rise and storm track shift north.  

Yeah I'm not saying we want +NAO or that having a +NAO during this time frame wouldn't matter, just dissecting the modeling. I agree in that we definitely don't want it to trend to no positive heights at all...just that the current trend is minimal and largely non influential, at least how I see it. Have it continue to trend as you say to a ++NAO, then yeah, we have issues.

[packbacker]

1 minute ago, Jon said:

Yeah I'm not saying we want +NAO or that having a +NAO during this time frame wouldn't matter, just dissecting the modeling. I agree in that we definitely don't want it to trend to no positive heights at all...just that the current trend is minimal and largely non influential, at least how I see it. Have it continue to trend as you say to a ++NAO, then yeah, we have issues.

Ah...gotcha, I misread what you posted.  Thanks!

[Jon]

15 minutes ago, GaStorm said:

The -EPO has been a much more dominant feature in the past few years but has not led to too much snow unfortunately. Not sure if the AO had anything to do with that as well since I remember it was mainly positive. If the AO stays negative maybe that could be enough to get the job done?

Yes, -AO is always a better feature to have for sure.

[Jon]

13 minutes ago, griteater said:

A few of the "Cold Rain" axioms are at play here...1) EPO cold is centered over the heartland, and 2) the eye of the needle gets tighter when you don't have certain features.  The GFS suite shows the perils in this pattern - i.e. EPO delivers the cold, but it's in and out, and the next system that approaches cuts.  Euro wants to bring out a wave soon after the cold moves in, and maximizes the limited timing window.  Who knows how that plays out, the 2 suites have some vast differences with the wave handling which are to be expected, but you need all the help you can get here to get a winter storm in terms of timing, transient NAO blocking, and SE Canada lows to help to suppress the storm track.

Agree...the window will be small here and it will take a lot of luck to get any snow below TN/NC, or even in NC outside of the apps. This isn't a blockbuster pattern by any means...but at least it isn't a torch, so I'll take my chances!

[GaStorm]

I think we can score with this pattern especially if there are a couple systems with the first one laying down snow to our north. The AO is also going neutral to negative within 10 days as well.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao_index_ensm.shtml

 

[MichaelJ]

Don't want to quote it because it would take up a lot of space but the -EPO post above by Jon is excellent, a 5* post for sure, well done sir

[SN_Lover]

12z GFS FROPA with really really cold air on the backside. 

[griteater]

1 minute ago, SN_Lover said:

12z GFS FROPA with really really cold air on the backside. 

Better looking run so far, we'll see if it can do anything here shortly

[Wow]

4 minutes ago, SN_Lover said:

12z GFS FROPA with really really cold air on the backside. 

Very cold.  Good opportunity to pull off a Jan '88 setup with that kind of look.

[Cary_Snow95]

2 minutes ago, griteater said:

Better looking run so far, we'll see if it can do anything here shortly

Fropa?

[Wow]

GFS wimps out the wave with the dominant HP but actually encouraged by that.

[mackerel_sky]

3 minutes ago, Cary_Snow95 said:

Fropa?

FROntal PAssage

[griteater]

12z Canadian has cool down Jan 5-6, then looks like it will have a big cutter at the end of its run

[griteater]

1 minute ago, Wow said:

GFS wimps out the wave with the dominant HP but actually encouraged by that.

Think that wave in Cali/Nevada will eventually kick out though with SW flow

[Poimen]

The GFS is similar to the EC from a few runs ago when it developed a GOM low that moved up the SE coast in the same general time frame. While the GFS is well offshore, the pattern suggests a classic GOM/SE baroclinic zone. This will need to be watched, IMO. 

[SN_Lover]

Just now, Poimen said:

The GFS is similar to the EC from a few runs ago when it developed a GOM low that moved up the SE coast in the same general time frame. While the GFS is well offshore, the pattern suggests a classic GOM/SE baroclinic zone. This will need to be watched, IMO. 

Thinking overrunning here also. 

[Wow]

With the big FROPA from the arctic jet covering the country and the STJ depressed into the E Pac, I can't imagine we won't get a moisture-packed wave out of this pattern.

[Wow]

1 minute ago, SN_Lover said:

Thinking overrunning here also. 

Exactly.   We want the STJ trough backing into the E Pac with the -EPO ridge overhead to throw us a wet system into this arctic air that is everywhere.  Wld set up a widespread event far south from OK to the east coast ala '88.