Pattern Change thread

[dryslot]

I just wish my eyes were open. There's got to be pics of me on the boards with eyes open.

Pattern change

12 less beers and they prob would have been open......

[CCPSUSuperstorm2010]

Aleutian Island ridging is the key to this pattern. GFS is weaker with the ridging signal, while the GFS ensemble means, Canadian ensemble means and to an extent the EURO ensembles show a stronger ridging pattern involved after D10. H5 looks amazing for the weekend after Thanksgiving into the following weekend. Problem is I will be in Buffalo, NY for Thanksgiving. Hopefully this pattern will become clearer before I leave next Thursday. Ridge builds into Aleutian Islands around the 23-24th, troughing moves from the Aleutian islands into the Gulf of Alaska +EPO ridging begins to hedge into the western US and then the troughing over the western US(-PNA) begins to move eastward into the central US for the 25-26th as a GLC moves through with a cold frontal passage and then the trough moves into the eastern US. Positoning of the trough axis and PV orientation will determine the nature of the shortwave trough for that Thanksgiving weekend period and whether or not we get our snowstorm that weekend into early the following week. The Aleutian island chain atmospheric condition drives this pattern home, the -NAO west based block certaintly enforces the +PNA ridging and more west based trough axis over the APPS then say over the I95 corridor. THe models obliterate the SE ridge idea, with the exception of the EURO. EURO holds the ridge for the 26th. Key is what will the EURO begin to focus on for the days following the 26th? 00z GFS op and ensemble means push the SE ridge out into the central Atlantic ocean around 300 hours, while also losing the -NAO blocking.

[weatherwiz]

Well, well, well...some pretty big encouraging signs on the 0z euro post-thanksgiving...pattern looks real good for snow potential after turkey day which is what many have been thinking anyways but it's nice to see the euro show it.

[40/70 Benchmark]

One week.....one week remaining in the season.....

[nzucker]

Well, well, well...some pretty big encouraging signs on the 0z euro post-thanksgiving...pattern looks real good for snow potential after turkey day which is what many have been thinking anyways but it's nice to see the euro show it.

In my opinion, the pattern doesn't look good as all; there's a two-day cold shot after Thanksgiving that's pretty legitimate, but the trough is quickly moving out of the Northeast. You can see that there's zonal flow across the entire CONUS with almost everyone in the country being above average...heights in the Northern Plains have gone from 522dm during the upcoming cold shot to over 550dm. We also have a 980mb low developing in the GoA which is blasting warm air into North America and attempting to scour out our troughing. Even with a solid west-based -NAO, the Pacific is winning the battle, and this makes sense given that the Niña will be rapidly intensifying at this point with strong trade winds, low AAM, and an incoherent MJO. Everything about the ECM is a typical Niña pattern where we get a big cutter, then a short-lived but intense cool down followed by a return to above average temperatures. This would set the stage for a poor beginning to December in my opinion.

The GFS also shows the change to an unfavorable Pacific in the longer range with more of a +EPO look coming into play...I'm not impressed with any pattern that features 516dm heights in the Gulf of Alaska. Here is Day 11 from the 0z GFS and it seems similar to the ECM with the cold air starting to fade:

[ORH_wxman]

In my opinion, the pattern doesn't look good as all; there's a two-day cold shot after Thanksgiving that's pretty legitimate, but the trough is quickly moving out of the Northeast. You can see that there's zonal flow across the entire CONUS with almost everyone in the country being above average...heights in the Northern Plains have gone from 522dm during the upcoming cold shot to over 550dm. We also have a 980mb low developing in the GoA which is blasting warm air into North America and attempting to scour out our troughing. Even with a solid west-based -NAO, the Pacific is winning the battle, and this makes sense given that the Niña will be rapidly intensifying at this point with strong trade winds, low AAM, and an incoherent MJO. Everything about the ECM is a typical Niña pattern where we get a big cutter, then a short-lived but intense cool down followed by a return to above average temperatures. This would set the stage for a poor beginning to December in my opinion.

The GFS also shows the change to an unfavorable Pacific in the longer range with more of a +EPO look coming into play...I'm not impressed with any pattern that features 516dm heights in the Gulf of Alaska. Here is Day 11 from the 0z GFS and it seems similar to the ECM with the cold air starting to fade:

Oh noes!! A -PNA/-NAO pattern for New England!! That's terrible.

[weatherwiz]

In my opinion, the pattern doesn't look good as all; there's a two-day cold shot after Thanksgiving that's pretty legitimate, but the trough is quickly moving out of the Northeast. You can see that there's zonal flow across the entire CONUS with almost everyone in the country being above average...heights in the Northern Plains have gone from 522dm during the upcoming cold shot to over 550dm. We also have a 980mb low developing in the GoA which is blasting warm air into North America and attempting to scour out our troughing. Even with a solid west-based -NAO, the Pacific is winning the battle, and this makes sense given that the Niña will be rapidly intensifying at this point with strong trade winds, low AAM, and an incoherent MJO. Everything about the ECM is a typical Niña pattern where we get a big cutter, then a short-lived but intense cool down followed by a return to above average temperatures. This would set the stage for a poor beginning to December in my opinion.

The GFS also shows the change to an unfavorable Pacific in the longer range with more of a +EPO look coming into play...I'm not impressed with any pattern that features 516dm heights in the Gulf of Alaska. Here is Day 11 from the 0z GFS and it seems similar to the ECM with the cold air starting to fade:

Are you talking about for more of the cold getting into our region? I don't think we end up in the core of the cold at all...in fact I see us as having maybe a day or two of way below normal temps then we moderate but still stay fairly below-normal.

What I like is the active look to the pattern and how it looks potentially good for overrunning scenarios. There definitely should be a huge temp gradient lined up somewhere in the Northeast but where does it set up? Won't know that until probably sometime early next week.

We might not see epic snow events down here but could certainly see some accumulating snows and if the pattern remains active all the storms, even if minor to moderate could add up pretty quickly.

Once we get into the middle half of December though and on the SE ridge will really start to setup and probably become quite strong and this is when things will become rather unfavorable for places like NYC/BDL/PVD but ORH/BOS should end up just fine but further north should get smoked.

[nzucker]

Oh noes!! A -PNA/-NAO pattern for New England!! That's terrible.

It's not a terrible pattern for those with significant elevation/latitude, but you can see the pattern is going downhill on the 0z ECM. That cold high pressure is going to slip off the coast, there's something forming over the Plains that is probably going to be a cutter/late redeveloper that would only hit the higher mountains or parts of NNE. I just don't think we can yet believe in this great pattern change that everyone has been so avidly discussing. We missed our best chance this week when we got the big ridge over Alaska with the PV coming into Canada; the -PNA killed it as we finally had a developed cold air source and a nice snow pack building to our north....temperatures have been running well above average every since the first 10 days of this month, and they will climb even more above average with the torch Tuesday/Wednesday of next week. I just think the pattern screams of cutter/cold shot/cutter/repeat....instead of a consistently cold pattern that allows us to cash in on any threat that moves our way. I'd like to see a long period of below average temperatures to prove that we can sustain cold anomalies and capitalize on storms tracking towards us; we haven't been able to sustain cold since February of last winter.

You have to admit, the Pacific looks atrocious Will, on both the GFS and ECM. We're actually going back to the old pattern that we had during the warm October instead of the "pattern change" towards cold/snow that so many were trumpeting. I am still unconvinced that late November/early December will be a memorable wintry period for SNE. I need to see a change in the Pacific before I can believe that we are really heading away from the warmth that's dominated this fall. I think a 516dm low over the GoA is more a continuation of the lame regime we've seen instead of a trend away from it. The models have lost the +PNA/western block that was showing up a few days ago. It's still far out though so there's time for change.

[ORH_wxman]

Once again Nate you are using a determinastic model to prove your skepticism about any snow chances post-Thanksgiving....I didn't hear a peep out of you about the 12z ECM at 240 hours which looked good.

The ensembles have looked good for awhile. Maybe you are right but I don't see a huge argument that convinces me that you are. I know how fickle LR forecasting is...but you have only interjected with your ideas when the operational ECM shows bad news at D10....not when it shows good news and certainly the ensemble mean has trashed your idea.

Its still early in the season so I fully admitted that these snow threats might not work out. The success wont be measured by how much snow we get, but by how the pattern evolved post-Tday

[nzucker]

Are you talking about for more of the cold getting into our region? I don't think we end up in the core of the cold at all...in fact I see us as having maybe a day or two of way below normal temps then we moderate but still stay fairly below-normal.

I think we could actually slip above average if you extrapolate the 0z ECM out past Day 10...the trough over our region is lifting out because there's a 516dm trough over the GoA and a minor weakness in the jet stream over the Pacific Northwest; this is allowing for zonal flow to control the pattern over the CONUS as heights are rapidly increasing in the Plains and Midwest. We do have a nice NAO block, but I wouldn't underestimate the influence of the Pacific regime in this case, especially since it occurs at a time when we will have a strengthening Niña and lack of favorable tropical forcing. I am pretty disappointed in this run....just a few days ago, the ECM was showing an epic +PNA forming in combination with the NAO block, but we've totally lost that. I'm just a bit distraught about the fact that we seem unable to sustain any cold anomalies and are launching into the typical La Niña pattern so early in the winter. We know we'll see some strong cold fronts in a strong La Niña; that's virtually guaranteed with Canada being colder than last winter and much lower global temperatures along with good NH snow cover coming in. But we need to have a long period of cold anomalies to allow us to take advantage of a storm, especially down towards the coastal plain where average temperatures are still in the mid-upper 40s during this period. It's a different story when we get into late December-late February as this NAO block would probably be sufficient at a climatologically colder time.

[weatherwiz]

Even if we were to slip above-normal I don't think it would be all that significant, and significant warming would probably hold off another few weeks or so. With a -NAO block like that it could be just enough to keep us from really warming...we would still be within a nice temperature gradient and given the active look in the pattern we could end up doing quite well. As long as we aren't seeing any significant ridging occur in the east even with the more zonal flow I would think the -NAO would be enough to get some and keep some colder air locked into the Northeast.

[nzucker]

Once again Nate you are using a determinastic model to prove your skepticism about any snow chances post-Thanksgiving....I didn't hear a peep out of you about the 12z ECM at 240 hours which looked good.

The ensembles have looked good for awhile. Maybe you are right but I don't see a huge argument that convinces me that you are. I know how fickle LR forecasting is...but you have only interjected with your ideas when the operational ECM shows bad news at D10....not when it shows good news and certainly the ensemble mean has trashed your idea.

Its still early in the season so I fully admitted that these snow threats might not work out. The success wont be measured by how much snow we get, but by how the pattern evolved post-Tday

You are mistaken, Will...you keep thinking I have some "stake" in proving my forecast or ideas. All I'm doing is analyzing a run of the models, in this case the 0z ECM, and saying what it shows. I'm also trying to tie it into what I've learned about how the Pacific acts when a strong La Niña is intensifying and we don't have a coherent MJO signal. I think the idea of a +EPO and short-lived cold shot makes more sense than some of the weenie runs that we've seen; I believe we will see a strong cold front around Thanksgiving, but I doubt it will last more than a few days, and I don't think that'll be enough to rack up snowfall. It's also late November/early December, when we don't usually get that much snow anyway. I think you agree that an extremely snowy period is unlikely according to climo, which is only trumped when we have a truly fantastic pattern. The pattern, to me, looks average to sub-par despite a nice NAO block. The NAO is also less important this early on, and most important later in the winter during cut-off season.

I saw the 12z ECM and I wasn't that impressed. I never like the idea of a GoA low limiting potential for cold air, especially when it's super early in the season. Places like Boston, Hartford, coastal CT/RI, and NYC need a fairly cold airmass to see significant snowfall at this time of year. A pattern in which the PV moves into Siberia and cuts off Canada's cold air supply is not going to succeed. I also think the Pacific ridge looked too far west, displaced, on the 12z ECM...we'd want the ridge axis to be more towards Idaho or Montana, but the pattern shown would probably lead to a -PNA and a surfeit of lakes cutters. Here is what I saw....nice Atlantic but bad Pacific, and the Pacific is more powerful, especially early on:

[ORH_wxman]

The bottom line is that you can't use a deterministic run to make your point when its 240 hours out. Ensemble mean always wins at that time frame, thats why we bother mentioning them and make comments like "well its past 144 hours so take it with a huge grain of salt"

[40/70 Benchmark]

I think we could actually slip above average if you extrapolate the 0z ECM out past Day 10...the trough over our region is lifting out because there's a 516dm trough over the GoA and a minor weakness in the jet stream over the Pacific Northwest; this is allowing for zonal flow to control the pattern over the CONUS as heights are rapidly increasing in the Plains and Midwest. We do have a nice NAO block, but I wouldn't underestimate the influence of the Pacific regime in this case, especially since it occurs at a time when we will have a strengthening Niña and lack of favorable tropical forcing. I am pretty disappointed in this run....just a few days ago, the ECM was showing an epic +PNA forming in combination with the NAO block, but we've totally lost that. I'm just a bit distraught about the fact that we seem unable to sustain any cold anomalies and are launching into the typical La Niña pattern so early in the winter. We know we'll see some strong cold fronts in a strong La Niña; that's virtually guaranteed with Canada being colder than last winter and much lower global temperatures along with good NH snow cover coming in. But we need to have a long period of cold anomalies to allow us to take advantage of a storm, especially down towards the coastal plain where average temperatures are still in the mid-upper 40s during this period. It's a different story when we get into late December-late February as this NAO block would probably be sufficient at a climatologically colder time.

I stopped reading when I saw that because if I went any further, then I'd prob end up making a noose out of some tube socks.

Its gonna snow and snow relatively soon.....name me a season in which you couldn't extrapolate out to the fourth of July and find a warm up...Christ.

[ORH_wxman]

Nate, the 00z ECM looks bad at 240h, I'm not disagreeing with you...but I'm just telling you it doesnt matter. Until we see some ensmble support for that crappy pattern, I do not buy it.

You obviously are getting married to your idea of bad patterns. A -PNA/-NAO pattern is generally good here...I'm not sure what you are describing. Yes of course if the NAO isn't powerful enough and we get some sort of monstrous PAC signal that destroys our setup then we won't see a good snow threat setup...but that isn't in the cards right now yet....except on your 00z ECM run right now at 240h.

Give me a reason why I should believe the 00z ECM OP run vs the ensembles at that time frame?

[40/70 Benchmark]

The bottom line is that you can't use a deterministic run to make your point when its 240 hours out. Ensemble mean always wins at that time frame, thats why we bother mentioning them and make comments like "well its past 144 hours so take it with a huge grain of salt"

I know it was going to snow last May because I extrapolated the 3 mth CFS.

[weatherwiz]

I stopped reading when I saw that because if I went any further, then I'd prob end up making a noose out of some tube socks.

Its gonna snow and snow relatively soon.....name me a season in which you couldn't extrapolate out to the fourth of July and find a warm up...Christ.

[40/70 Benchmark]

Heavy heavy stuffing, and some winter event tracking for dessert.

[40/70 Benchmark]

Oh noes!! A -PNA/-NAO pattern for New England!! That's terrible.

There isn't a locale from the latitude of N CT and N RI, points N that could not benefit from that pattern in Dec.....I don't care if you live on a buoy in Boston Harbor.

[weatherwiz]

There isn't a locale from the latitude of N CT and N RI points N that could not benefit from that pattern in Dec.....I don't care if you live on a buoy in Boston Harbor.

We all should do very well in December.

[40/70 Benchmark]

We all should could do very well in December.

[ORH_wxman]

There isn't a locale from the latitude of N CT and N RI, points N that could not benefit from that pattern in Dec.....I don't care if you live on a buoy in Boston Harbor.

The pattern could go to crap...its very possible...but what Nate is insisting on is based solely on the OP run. 12z looked good at 240h (he disagreed....but I disagree with that)

[ski MRG]

Heavy heavy stuffing, and some winter event tracking for dessert.

I love dessert.

[40/70 Benchmark]

The pattern could go to crap...its very possible...but what Nate is insisting on is based solely on the OP run. 12z looked good at 240h (he disagreed....but I disagree with that)

Any one could, but like you said, you have to show me more than a single deterministic run extrapolated from day 10 to convince me that it will.

[weatherwiz]

Euro ENS still look pretty good in the long-range...might have some issues towards the end but it still looks like we would be in a below-average temp pattern and a nice looking pattern as well.

[weatherwiz]

Man, that looks like it has potential to be a pretty fun pattern. As long as we can keep a fairly -NAO that should help to bring in reinforcing shots of cold air every once in a while...at least we know we won't be under one rotting airmass like last winter.

[ORH_wxman]

Euro ENS still look pretty good in the long-range...might have some issues towards the end but it still looks like we would be in a below-average temp pattern and a nice looking pattern as well.

How did you know, or were you just talking about 12z? You wouldn't have been able to see 00z that quick unless you have wsi.

[weatherwiz]

How did you know, or were you just talking about 12z? You wouldn't have been able to see 00z that quick unless you have wsi.

I went here

http://www.ecmwf.int...l!2010111800!!/

Said base time was 0z Thursday

[ORH_wxman]

I went here

http://www.ecmwf.int...l!2010111800!!/

Said base time was 0z Thursday

Yeah I wasnt sure how fast they updated...looks like pretty quick tonight. They give ensemble mean out to 240....wsi gives us out to 360h...but beyond 240 is very iffy anyway.

[weatherwiz]

Yeah I wasnt sure how fast they updated...looks like pretty quick tonight. They give ensemble mean out to 240....wsi gives us out to 360h...but beyond 240 is very iffy anyway.

I was kind of shocked to see it updated actually when I checked.