January Mid/long Range Winter Discussion

[Cold Rain]

I want to illustrate something.  I hope I make this easy to understand.  Most days, I post index charts, which are modestly helpful in evaluating the upcoming pattern, assuming they turn out to be in the vicinity of accurate.  But the index charts do not tell the whole story.  I think there is a tendency to look at favorable index values and correlate them to snow chances.  That isn't necessarily wrong (I do it too), but it is only half of the picture.  You need more information.  Here is more information:

 

First up, 500mb.  This is the GFS 312hr prog of the 500mb level.  I don't care far out it is or even if it turns out to be completely wrong.  That's not important.  What is important is that it shows how easy it is to have a substantial -AO/-NAO value and a +PNA value on an index chart and still have a horrible pattern for snow.

 

You can clearly see the -AO, -NAO, and +PNA configuration.  You can also clearly see that the PV is northwest of the Great Lakes.  Energy spins around the PV (which shows up in the form of our friend, the Lakes Low) and you have divergence aloft over the NE US/SE Canada, which is the opposite of what you need to lock in HP.  The PV is trapped in the wrong place.  I needs to be much farther east.

 

This setup allows the low to either cut or Miller B.  Look:

 

 

Next, we have the 850mb level.  Notice how the 850 0C line is not through or south of the SE (outside of the mountains).  This looks like a mostly rain event, with maybe a mix at the onset.  Where is all of the cold air?  We have blocking and +PNA etc. etc. etc.  But the pattern is still not conducive to a big winter storm.

 

 

And finally, we have the surface map.  Paltry, high pressure is exiting the NE as a low moves in from the west.

 

 

Again, this is just to show that it is not only possible, but quite easy to have favorable index values show up on a chart and simultaneously have a pattern that is not conducive to snow.

 

That said, getting blocking established is a good step.  The Pacific has to cooperate.  It can't continuously beat down the PNA ridge, and the blocking needs to allow some element of cross polar flow, ideally.

 

So, that's the scoop.  We're taking steps and making progress...at least it looks like it.  But don't expect that just because we have favorable index values, we will get snow and ice.  We have a better shot for sure, but it's not a lock, by any stretch.  It's the configuration of the variables that is important.  Hopefully, that part will come in time.

[packbacker]

There is a reason the Euro is showing a big cutter for the 17th potential, yes there is a ridge over southern Greenland but there is also a low over HB, anything amped up is going to cut, probably miller B.  The look on the 17th is similar to what is happening this weekend, big cutter, probably further east on the 17th, but not a coastal.  

 

So yes, we have a "-NAO" via the index but that low is messing things up and as long as it's there we are going to have to hope for a weak wave.  Now, both the GEFS/EPS both show the actual ridge (NAO block) dropping in between HB/DS past day 11 which is a better look.  So yes I am bearish on any short term chances but I hope end of Jan into Feb turn around.   

 

I was hopeful on the 13th chance but the GFS has now caved to the Euro (shocker) of the low over the lakes squashing anything and we get that reformer off the NE coast.  Could it dig more, sure, but not likely.

 

 

 

 

[packbacker]

I want to illustrate something.  I hope I make this easy to understand.  Most days, I post index charts, which are modestly helpful in evaluating the upcoming pattern, assuming they turn out to be in the vicinity of accurate.  But the index charts do not tell the whole story.  I think there is a tendency to look at favorable index values and correlate them to snow chances.  That isn't necessarily wrong (I do it too), but it is only half of the picture.  You need more information.  Here is more information:

 

First up, 500mb.  This is the GFS 312hr prog of the 500mb level.  I don't care far out it is or even if it turns out to be completely wrong.  That's not important.  What is important is that it shows how easy it is to have a substantial -AO/-NAO value and a +PNA value on an index chart and still have a horrible pattern for snow.

 

You can clearly see the -AO, -NAO, and +PNA configuration.  You can also clearly see that the PV is northwest of the Great Lakes.  Energy spins around the PV (which shows up in the form of our friend, the Lakes Low) and you have divergence aloft over the NE US/SE Canada, which is the opposite of what you need to lock in HP.  The PV is trapped in the wrong place.  I needs to be much farther east.

 

This setup allows the low to either cut or Miller B.  Look:

 

 

Next, we have the 850mb level.  Notice how the 850 0C line is not through or south of the SE (outside of the mountains).  This looks like a mostly rain event, with maybe a mix at the onset.  Where is all of the cold air?  We have blocking and +PNA etc. etc. etc.  But the pattern is still not conducive to a big winter storm.

 

 

And finally, we have the surface map.  Paltry, high pressure is exiting the NE as a low moves in from the west.

 

 

Again, this is just to show that it is not only possible, but quite easy to have favorable index values show up on a chart and simultaneously have a pattern that is not conducive to snow.

 

That said, getting blocking established is a good step.  The Pacific has to cooperate.  It can't continuously beat down the PNA ridge, and the blocking needs to allow some element of cross polar flow, ideally.

 

So, that's the scoop.  We're taking steps and making progress...at least it looks like it.  But don't expect that just because we have favorable index values, we will get snow and ice.  We have a better shot for sure, but it's not a lock, by any stretch.  It's the configuration of the variables that is important.  Hopefully, that part will come in time.

 

LOL...we literally wrote the same thing....your lakes low has got to get out of there.  I think it will if that Greenland block is as strong as it's currently modeled.

[packbacker]

Cold Rain - if you see on the 17th that hell forsaken low is still there but by the 13th it's actually pushed NW and the NAO block is undercutting...I have no clue if that's good or not but it's better than the alternative.  It's been so long since a big NAO block...LOL.

 

 

[Cold Rain]

Cold Rain - if you see on the 17th that hell forsaken low is still there but by the 13th it's actually pushed NW and the NAO block is undercutting...I have no clue if that's good or not but it's better than the alternative.  It's been so long since a big NAO block...LOL.

 

I know.  It's hard to remember the last time we've seen blocking like this.  I would rather see that big gyre move underneath the blocking and take up a position somewhere in SE Canada or even just east of there.  When your cold air source moves way up to the northwest, we can still have negative anomalies in the SE (like your maps show), but I'm afraid the air won't be cold enough for anything other than rain.  I like the way the Aleutian low retrogrades though.  That is good.

 

Do you have 850 temps for the same time frames?

[DopplerWx]

same old same old, suppressed and cold on 12z.

[SnowNiner]

Thanks guys for the explanation.  Let me ask this question, then.  It's the tropospheric polar vortex that is causing the great lakes lows where they are?  So we need to the PV to shift east.  What would that do?  Wouldn't that also create lows in the NE where we need high pressures as well? 

 

It seems like blocking is always going to push the vortex south, which up front seem like a good thing.  Not sure still what is needed to improve the position of high pressures in this situation.  Blocking further south? Thanks.

[packbacker]

I know.  It's hard to remember the last time we've seen blocking like this.  I would rather see that big gyre move underneath the blocking and take up a position somewhere in SE Canada or even just east of there.  When your cold air source moves way up to the northwest, we can still have negative anomalies in the SE (like your maps show), but I'm afraid the air won't be cold enough for anything other than rain.  I like the way the Aleutian low retrogrades though.  That is good.

 

Do you have 850 temps for the same time frames?

 

Agreed, but not sure if it's a deal killer in the long range.  Why I am hoping for a reshuffle around the 20th and start over in Feb.

[packbacker]

Thanks guys for the explanation.  Let me ask this question, then.  It's the tropospheric polar vortex that is causing the great lakes lows where they are?  So we need to the PV to shift east.  What would that do?  Wouldn't that also create lows in the NE where we need high pressures as well? 

 

It seems like blocking is always going to push the vortex south, which up front seem like a good thing.  Not sure still what is needed to improve the position of high pressures in this situation.  Blocking further south? Thanks.

 

Well maybe this is the start of a re-shuffle, d10 you can see a lobe NW of AK, lobe over Europe and a lobe over HB.  You also see the strong -AO and ridging into Greendland (-NAO).  This does deliver cold to the conus but just not snowy for the east.  Then by d13+ we see trop PV start to come together so maybe we moderate end of Jan, AO goes neutral and we hope we start again trying in Feb.  Just my opinion.  

I was hopeful we could sneak a light event in the next 10 days but that's looking less likely, IMO.  

[burgertime]

PV looks better placed to me on the GFS after Tuesday of next week. 

[FallsLake]

PV looks better placed to me on the GFS after Tuesday of next week. 

I'm only out to 153 and noticed that as well.  

[packbacker]

Unless things dramatically change on the modeling there is going to be a lot of places in the east well below climo for snow as Jan ends.  I's hard to imagine that everyone in the east (NE to Atlanta) exceeding climo in Feb alone.  The gist is it seems very likely some, potentially alot of areas, will finish below climo for snow in the east and maybe a select few will get lucky to reach climo.

 

Like I said, I will happily take another 98 repeate, give me 2-3" and call it a winter.  Was hoping for 5" but it's going to be tough.

[packbacker]

PV looks better placed to me on the GFS after Tuesday of next week. 

 

 

I'm only out to 153 and noticed that as well.  

 

It swings through, we actually moderate for a day or so and then it reforms with the block over GD sinking south after this.  Ensembles agree on this.

[Cold Rain]

Thanks guys for the explanation.  Let me ask this question, then.  It's the tropospheric polar vortex that is causing the great lakes lows where they are?  So we need to the PV to shift east.  What would that do?  Wouldn't that also create lows in the NE where we need high pressures as well? 

 

It seems like blocking is always going to push the vortex south, which up front seem like a good thing.  Not sure still what is needed to improve the position of high pressures in this situation.  Blocking further south? Thanks.

 

I'm not sure that's an easy question to answer.  The Lakes low is just a function of energy moving through in the northern stream.  Sometimes these waves are weak and sometimes they're strong.  They follow the track of the northern jet stream.  Sometimes that's around the tropospheric PV, sometimes it's zonal, sometimes it's straight south, if the PNA ridge is tall/sharp enough.  Often, these clipper-type systems traverse through the Lakes and on east.  Behind them we turn colder.

 

When you have a split flow like we do, with a relatively benign PNA ridge, the streams tend to stay separate.  The hope is to get a low in the northern stream go by to lay down the cold air, followed by a low in the southern stream to lay down the moisture.

 

Regarding the blocking, you're correct...it tends to displace the PV south, which is what we want.  But depending on where the blocking sets up and how it sets up, the PV could get displaced over the Lakes, over SE canada, northeast of there or even farther west.  So, blocking is good, but we still need to get the PV in the right spot.  Having a PV trapped in SE Canada or even a bit farther east will establish confluence over the NE, which will help us.  There are other ways to get good timing and get a good snowstorm, but that's what I like to see unfold, as I think it opens the window a bit more for us.

 

I don't know if that makes any sense or not, but it's complicated and dynamic the way all of these things work together.  Too much energy in the flow can really mess up timing and mess up amplification and mess up model forecasts.  And right now, we have a LOT if energy in the flow. 

[burgertime]

Well by next weekend it's close but it looks like the cold is retreating. Have energy in a good spot just need the cold air to stay in place. 

[packbacker]

I'm not sure that's an easy question to answer.  The Lakes low is just a function of energy moving through in the northern stream.  Sometimes these waves are weak and sometimes they're strong.  They follow the track of the northern jet stream.  Sometimes that's around the tropospheric PV, sometimes it's zonal, sometimes it's straight south, if the PNA ridge is tall/sharp enough.  Often, these clipper-type systems traverse through the Lakes and on east.  Behind them we turn colder.

 

When you have a split flow like we do, with a relatively benign PNA ridge, the streams tend to stay separate.  The hope is to get a low in the northern stream go by to lay down the cold air, followed by a low in the southern stream to lay down the moisture.

 

Regarding the blocking, you're correct...it tends to displace the PV south, which is what we want.  But depending on where the blocking sets up and how it sets up, the PV could get displaced over the Lakes, over SE canada, northeast of there or even farther west.  So, blocking is good, but we still need to get the PV in the right spot.  Having a PV trapped in SE Canada or even a bit farther east will establish confluence over the NE, which will help us.  There are other ways to get good timing and get a good snowstorm, but that's what I like to see unfold.

 

I don't know if that makes any sense or not, but it's complicated and dynamic the way all of these things work together.  Too much energy in the flow can really mess up timing and mess up amplification and mess up model forecasts.

 

Let's go back to some of our fav nino winter storms...look just east of Nova Scotia.  I am not seeing this, yet...

 

 

[Cold Rain]

^ Good depiction of blocking, a PV displaced SE, an Aleutian low in a good spot, and an active STJ.  That's how you do it right there.

[packbacker]

^ Good depiction of blocking, a PV displaced SE, an Aleutian low in a good spot, and an active STJ.  That's how you do it right there.

 

It's not complicated....lot of folks running around here on blind faith.   I guess ignorance is bliss.

[burgertime]

Well the CMC has a clipper for the mountains and eastern NC at least. GFS out past 200 has cold retreating as the pattern reloads.

[Brick Tamland]

It's not complicated....lot of folks running around here on blind faith.   I guess ignorance is bliss.

 

Not really blind faith when a lot of mets and others gave good reasons and evidence as to why we should have a good winter. If it doesn't end up that way and goes against most of the evidence of what has given us good winters before, then that's the way it goes. But it's not blind faith, and if you go against the research of the past just because you are always pessimistic and get it right, then I guess you should get a cookie.

[packbacker]

Yeah, it's a nao block...but a lot a good it's doing, LOL.  

 

 

[packbacker]

Not really blind faith when a lot of mets and others gave good reasons and evidence as to why we should have a good winter. If it doesn't end up that way and goes against most of the evidence of what has given us good winters before, then that's the way it goes. But it's not blind faith, and if you go against the research of the past just because you are always pessimistic and get it right, then I guess you should get a cookie.

 

My 6 year old told me today...'hey Dad, it's going to snow today because it's cold'.  I told him..."hey son, don't be a Brick".

[Cold Rain]

Yeah, it's a nao block...but a lot a good it's doing, LOL.  

 

If we could move the US just a bit to the northwest or even just west, that map would be great!

[packfan98]

Yeah, it's a nao block...but a lot a good it's doing, LOL.  

You get a low...and you get a low...everybody gets a LOW!!!!!

[Cold Rain]

Not really blind faith when a lot of mets and others gave good reasons and evidence as to why we should have a good winter. If it doesn't end up that way and goes against most of the evidence of what has given us good winters before, then that's the way it goes. But it's not blind faith, and if you go against the research of the past just because you are always pessimistic and get it right, then I guess you should get a cookie.

 

It takes one big snowstorm to be above climo on snow.  We definitely have the ingredients for it this winter.  Can we put them together?

[Cold Rain]

What we are seeing a real lack of this year is strong high pressure systems.  High pressure is good.

[Brick Tamland]

My 6 year old told me today...'hey Dad, it's going to snow today because it's cold'.  I told him..."hey son, don't be a Brick".

 

Lots of good mets gave great evidence as to why this winter should be above average for snowfall in our area. You went against the evidence because your always pessimistic about snow here. Congrats.

[burgertime]

I'm holding out hope until this weekend. For next week and into next weekend. Probably just being a weenie with that, but it seems like the cold air is retreating awfully fast for the setup. 

[burgertime]

Of course on the GFS @240 it looks like something big could be in the works. This is the story of the SE during most winters. 

[packbacker]

Lots of good mets gave great evidence as to why this winter should be above average for snowfall in our area. You went against the evidence because your always pessimistic about snow here. Congrats.

 

I said it's going to snow for our area, probably less than 5".  Your a little further N, maybe you get 6".  Just saying 98 is looking awfully good right now.