Uncertainty

The gfs been dreadful since the most recent update. Shame because it had a few good successes over the past two years. However, I guess the constant false strat alarms it has been seeing recently could be said to be evidence it was sniffing something real, even if the timing was out. This is a big shift from the 46 Nick, the biggest correction I have seen since we started seeing these zonal plots like this (granted that’s not been too long). Could the zonal trop forecast in early Feb be an attempt to flush down the positive anoms from the top? Or just a reaction to the mjo reaching the IO? clusters do look interesting in the extended too…

The WAF into the strat isn’t going away imho. I’d say with the Aleutian low / Barents -Kara ridging… …it’s going to lead to a full on absorbitive event and thus a major SSW by the end of Jan perhaps early Feb. The big players are seeing this too and this forum is going to be a lot, lot busier by mid Feb. A way off yes and tonnes more rain of the troublesome variety to gush under the bridge in the meantime, but the pattern above is very good for a significant pv disruption. As I have said before I follow an eclectic array of sources from, even some many of the more orthodox meterology folk might look down on but all of them correlate towards a late winter cold spell. I’m not one to make a big call but, like others, I called the early December spell (as did many others, mostly by following the seasonals) Meant to send this yesterday. Today has not changed my outlook!

Up to a day or so ago all 3 were really keen on sceuro heights, they’ve obviously seen something they didn’t know before. There were a few GEFS members doing this 3 days ago was the first sign I saw. Taking away the strat impacts, I’m with @Nick F and feel we’re always in the game with low euro heights. We just came out of a frustrating period where a good hemispheric profile was betrayed by a euro high. If they are what we are to get then bring it on and long may they continue.

It’s not even January Luke. Only time you could even think about that would be if the strat was forecast to be very strong and maintain pv of doom (e.g date records) strength to mid Feb. Perhaps later in Jan if that becomes the case then maybe but that’s not where we’re at. Not saying it looks ideal but as the regimes show there’s plenty of ways Jan could go let alone Feb.

Thanks Nick. Yep that scandi trough should allow it to pick up again. Is a shame as with the persisting Aleutian low even a week of a decent scandi block and I think we’d of ended up with an ssw late Jan. FWIW, the 46 had a weak warmish signal into Feb. Nothing’s screaming pv of doom for the time being.

Nothing particularly exciting BA, it doesn’t supercharge the strat though. In fact, it edges zonal winds lower by the end of the run. I’m more interested if the 12z eps follows the GEFS in the extended, I’m guessing it does by the clusters. Are you able to post the change in slp from run to run in the eps extended?

Looking to the next regime now, and tentative signs that our +NAO / euro high combo might be waning beyond day 10… Pretty good support for an MAR and a Baltic trough. Eps not fully on board but 20 odd members go for the MAR. The mjo has taken on more of a standing wave look to it, reaching but fading in phase 7. As many of the bases for the composite will be based on a more coherent mjo, I’m dubious as to how much influence it’s having. Still, the January p7 Nina composite isn’t totally irreconcilable with the above I wonder what the 46 will do with the tropical signal (and, perhaps more importantly, what will it do with the strat as BA has alluded to). My punt is it’ll have the strat stronger by the end of the run, but we’ll see. It looks like the low at day 9-10 will progress E and erode the euro heights. If this verifies it wouldn’t take much to go colder. Best we can do at the moment and probably not great for continuing the WAF into the strat but there is some agreement there. Long way to go though and said low euro heights are notoriously difficult to verify. Original post: https://community.netweather.tv/topic/98132-model-output-discussion-christmas-week-and-beyond/?do=findComment&comment=4779749

Looking to the next regime now, and tentative signs that our +NAO / euro high combo might be waning beyond day 10… Pretty good support for an MAR and a Baltic trough. Eps not fully on board but 20 odd members go for the MAR. The mjo has taken on more of a standing wave look to it, reaching but fading in phase 7. As many of the bases for the composite will be based on a more coherent mjo, I’m dubious as to how much influence it’s having. Still, the January p7 Nina composite isn’t totally irreconcilable with the above I wonder what the 46 will do with the tropical signal (and, perhaps more importantly, what will it do with the strat as BA has alluded to). My punt is it’ll have the strat stronger by the end of the run, but we’ll see. It looks like the low at day 9-10 will progress E and erode the euro heights. If this verifies it wouldn’t take much to go colder. Best we can do at the moment and probably not great for continuing the WAF into the strat but there is some agreement there. Long way to go though and said low euro heights are notoriously difficult to verify.

There’s a time to throw in the towel and this ain’t it. Sure the most likely outcome is that January ends up milder than avg but we only know the general set up for the next 10-15 days, anything after that and you’re into JMA / CFS / EC weeklies territory. Unlike other Jans, we also have an SPV forecast to weaken (from a v high base), the mjo in a favourable phase for blocking (albeit dubious amplitude) and a NH profile forecast (in the extended) that is not far off ideal for causing an ssw (albeit most likely a displacement). In fact if it weren’t for the info in brackets we’d be heading back to the freezer (damn you brackets!) In early 2020, we had an mjo forecast to sit in P3/4 and a rampant, record setting fully coupled SPV. If this were the case now there would be justifiable towel throwage, even, in fact especially from me! The strat for me is ripe for the taking, its present strength is also its weakness you might say. The Aleutian low looks to stick around for there next 10-15 days at least, if we can tag team it with a genuine Scandi - Greenland pattern for a week or so then the long term outlook at all levels would be subject to big changes. Original post: https://community.netweather.tv/topic/98132-model-output-discussion-christmas-week-and-beyond/?do=findComment&comment=4778613

There’s a time to throw in the towel and this ain’t it. Sure the most likely outcome is that January ends up milder than avg but we only know the general set up for the next 10-15 days, anything after that and you’re into JMA / CFS / EC weeklies territory. Unlike other Jans, we also have an SPV forecast to weaken (from a v high base), the mjo in a favourable phase for blocking (albeit dubious amplitude) and a NH profile forecast (in the extended) that is not far off ideal for causing an ssw (albeit most likely a displacement). In fact if it weren’t for the info in brackets we’d be heading back to the freezer (damn you brackets!) In early 2020, we had an mjo forecast to sit in P3/4 and a rampant, record setting fully coupled SPV. If this were the case now there would be justifiable towel throwage, even, in fact especially from me! The strat for me is ripe for the taking, its present strength is also its weakness you might say. The Aleutian low looks to stick around for there next 10-15 days at least, if we can tag team it with a genuine Scandi - Greenland pattern for a week or so then the long term outlook at all levels would be subject to big changes.

Very early days, but this anomaly isn’t far from one that would really perturb the strat Aleutian low, Ural high. Would like to see more of a vertical element to the WAA and for the ridge to push westwards a little more. It’s a big ask, but it’s a start. Yesterdays had a scandi trough. GFS has a look at the same sort of pattern as the 12z ec, though a little later in the run Straws yes, but this is what we need to look for.

The January blocking signal on the ec46 is consistent now. @northwestsnow in answer to your questioning its worth.. what else should one use ? Gfs extended? JMA weeklies? The cfs? Or should we simply abandon sub seasonal forecasting altogether? It may be the final frontier but it is my area of interest. IMHO The 46 is the best we have and right now it holds significant interest for coldies into January. Notably, it weakens the zonal winds at 10hpa slightly below average in the first half of Jan. The GEFS are similar and we also have consistency from its previous run. Seen as the upcoming quasi zonal spell is likely trop driven anyway there remains no convincing evidence that a pv of doom is on the horizon nor a consistent signal for coupling. @jules216 you’re right it doesn’t show an ssw but it wouldn’t yet and the trop patterns it advertises, especially late Jan with a decent Ural block, could perhaps set something significant off into February. (It does look like that’s when one might occur now). We can therefore examine any blocking forecast with less scepticism than would be the case under a strong, coupled strat regime. The precip charts for weeks 3 - 6 show the unsettled weather favouring a southerly track W3 W4 W5 W6 The MJO passing through 7-8-1 would also support a more blocked pattern. This is indeed what is advertised. The JMA weeklies hint at an MAR for the latter half of Jan @CreweCold You’re very downbeat at present mate (you don’t need to explain why to me ) but are you backing the cfs over the eps for the 2nd half of Jan? So it’s a case of continued intrigue into January, though a 15+ day of westerly winds does look likely in the interim. My punt is that cold chances resume around mid month. Another westerly spell in early Feb followed by an ssw. If it’s an absorptive event then an epic late Feb / Early March could follow. Original post: https://community.netweather.tv/topic/98132-model-output-discussion-the-run-up-to-christmas/?do=findComment&comment=4776508

The January blocking signal on the ec46 is consistent now. @northwestsnow in answer to your questioning its worth.. what else should one use ? Gfs extended? JMA weeklies? The cfs? Or should we simply abandon sub seasonal forecasting altogether? It may be the final frontier but it is my area of interest. IMHO The 46 is the best we have and right now it holds significant interest for coldies into January. Notably, it weakens the zonal winds at 10hpa slightly below average in the first half of Jan. The GEFS are similar and we also have consistency from its previous run. Seen as the upcoming quasi zonal spell is likely trop driven anyway there remains no convincing evidence that a pv of doom is on the horizon nor a consistent signal for coupling. @jules216 you’re right it doesn’t show an ssw but it wouldn’t yet and the trop patterns it advertises, especially late Jan with a decent Ural block, could perhaps set something significant off into February. (It does look like that’s when one might occur now). We can therefore examine any blocking forecast with less scepticism than would be the case under a strong, coupled strat regime. The precip charts for weeks 3 - 6 show the unsettled weather favouring a southerly track W3 W4 W5 W6 The MJO passing through 7-8-1 would also support a more blocked pattern. This is indeed what is advertised. The JMA weeklies hint at an MAR for the latter half of Jan @CreweCold You’re very downbeat at present mate (you don’t need to explain why to me ) but are you backing the cfs over the eps for the 2nd half of Jan? So it’s a case of continued intrigue into January, though a 15+ day of westerly winds does look likely in the interim. My punt is that cold chances resume around mid month. Another westerly spell in early Feb followed by an ssw. If it’s an absorptive event then an epic late Feb / Early March could follow.

I’m not convinced on zonal oblivion taking over in early Jan just yet (nor am I suggesting deep, sustained cold is imminent either!). However, the ‘problem’ we have over the next fifteen days isn’t a lack of blocking: it’s the you know where heights. Still chugging away over 300 hours away on the GEPS The eps clusters are devoid of +NAO after day 10 (not sure I totally agree mind) but that still shows we’re a little way off throwing the towel in yet. Only 20% actually look conducive to cold, and I’m not sure why cluster 1 isn’t +NAO. Still, better than blue across the board. The famous Christmas collapse occurred almost a year ago, just for once could we please have it occur the opposite way round this time!

Clusters day 8-10 One of those where the algorithm assigning +NAO to everything doesn’t tell the whole story. All about that low and the manner in which it is squeezed between the euro blob and the Atlantic ridge. Clusters beyond day 10: +NAO options fade away, lots of blocking and mid Atlantic ridges. None of them scream deep cold and snow but the lack of zonality is notable. The GEFS, predictably, lose the stronger blocking signal earlier on from the 12z but do end on an interesting note After the low clears, The GEPS remain really keen on an MAR There’s also some developing ural ridging - would love to see a link up to that and indeed for the Ural / Scandi blocking to become the focus for early January. Those new to this game need to know this: If we don’t get a block developing over this region in the next few weeks the stratospheric vortex aloft will, most likely, overpower any meaningful attempt at blocking. This also makes future attempts at Scandi blocking harder and thus a +NAO late winter period becomes harder to shift. Personally, given the pacific configuration, I remain fairly convinced we will see an SSW this winter. But if this mjo cycle fails to deliver the goods it could well be into mid February that this manifests thus we would be looking for a March 13 or Feb 18 bookend to winter. All in all, and with Christmas snow still plausible for many in the N, a fascinating outlook and potentially a defining one for the months ahead, as is often the case at this crucial time of year. Original post: https://community.netweather.tv/topic/98087-model-output-discussion-the-cold-has-arrived/?do=findComment&comment=4771465

Clusters day 8-10 One of those where the algorithm assigning +NAO to everything doesn’t tell the whole story. All about that low and the manner in which it is squeezed between the euro blob and the Atlantic ridge. Clusters beyond day 10: +NAO options fade away, lots of blocking and mid Atlantic ridges. None of them scream deep cold and snow but the lack of zonality is notable. The GEFS, predictably, lose the stronger blocking signal earlier on from the 12z but do end on an interesting note After the low clears, The GEPS remain really keen on an MAR There’s also some developing ural ridging - would love to see a link up to that and indeed for the Ural / Scandi blocking to become the focus for early January. Those new to this game need to know this: If we don’t get a block developing over this region in the next few weeks the stratospheric vortex aloft will, most likely, overpower any meaningful attempt at blocking. This also makes future attempts at Scandi blocking harder and thus a +NAO late winter period becomes harder to shift. Personally, given the pacific configuration, I remain fairly convinced we will see an SSW this winter. But if this mjo cycle fails to deliver the goods it could well be into mid February that this manifests thus we would be looking for a March 13 or Feb 18 bookend to winter. All in all, and with Christmas snow still plausible for many in the N, a fascinating outlook and potentially a defining one for the months ahead, as is often the case at this crucial time of year.

Both the GEFS and GEPS have really flipped their projections over between runs, day 11 below but the big change is much earlier with a big change in the amplification off the eastern seaboard and corresponding height rises over Greenland. GEFS 6z GEFS12z Perhaps a slight southerly mean flow there. More hp influence and less westerly. GEPS 0z had Weak heights over Greenland and a weak southwesterly for us. GEPS 12z Note the cut off high over Greenland. A bit of a mess over us but that’s because the forecast for the behaviour of the weakening Atlantic low to the sw of us is just as, if not more uncertain than the Greenland regime to the north! I think this shift is notable and unusually large. The UKMO, whilst not ideal within the timeframe of the run, has really significant amplification taking place over Greenland and I’d have loved to see it’s day 8-10 charts. It’s also far more palatable than the hideous runs it has churned out of late, 0z today a case in point. I wouldn’t be surprised if the ec op churned out a really amplified run, given the evidence from the other two ens sets tonight. The one thing missing for coldies is the euro heights remain stubborn even on the above. It’s been said enough about shifting those but the profile to the N has improved considerably tonight so far. Here’s how the GEPS mean ends, plenty to consider then tonight as we wait for the eps to add their two penneth. Original post: https://community.netweather.tv/topic/98087-model-output-discussion-the-cold-has-arrived/?do=findComment&comment=4770768

Both the GEFS and GEPS have really flipped their projections over between runs, day 11 below but the big change is much earlier with a big change in the amplification off the eastern seaboard and corresponding height rises over Greenland. GEFS 6z GEFS12z Perhaps a slight southerly mean flow there. More hp influence and less westerly. GEPS 0z had Weak heights over Greenland and a weak southwesterly for us. GEPS 12z Note the cut off high over Greenland. A bit of a mess over us but that’s because the forecast for the behaviour of the weakening Atlantic low to the sw of us is just as, if not more uncertain than the Greenland regime to the north! I think this shift is notable and unusually large. The UKMO, whilst not ideal within the timeframe of the run, has really significant amplification taking place over Greenland and I’d have loved to see it’s day 8-10 charts. It’s also far more palatable than the hideous runs it has churned out of late, 0z today a case in point. I wouldn’t be surprised if the ec op churned out a really amplified run, given the evidence from the other two ens sets tonight. The one thing missing for coldies is the euro heights remain stubborn even on the above. It’s been said enough about shifting those but the profile to the N has improved considerably tonight so far. Here’s how the GEPS mean ends, plenty to consider then tonight as we wait for the eps to add their two penneth.

Not many times you see a band of snow crossing N England on Xmas eve. Unlikely of course. But… GEM ECM If Someone offered me the above on the big 3 for a random Xmas Eve - I would take it. Yet the mood on here has been despondent (I get why, you don’t need to tell me!). Just goes to show the forecast for the Xmas period is not finalised yet. PS Lol at the Icelandic spoiler! We’re back to square one!

I imagine they’re all wrong tonight Mike - but they’re clearly playing with outcomes most of us on here would find far more favourable than this morning! That ruddy Arctic high is the issue. They are so frustrating and in recent years have let us down. We really need it to take residence as near to us as possible - not slink back to NW Canada (v bad) or sink away into Siberia. If it is close enough it gives any amplification in our sector something to ‘grab hold of’. There something dubious about this whole thing, it doesn’t feel clear like the last episode did. In recent years without a huge signal things have fallen apart for us. We need 2-3 days of upgrades, but this is at least a start.

This chart is truly bizarre. One of the strangest charts I’ve ever seen. So… disorderly. I don’t even know where to start. Somehow it feels better than the 0z - as does the gfs in a more obvious way,

Much better gfs - GH edging closer not away and a stronger northerly. Notice on the euro view the fledgling GH has been undercut by the Atlantic over the Azores. Should help to prop up the high. Arctic heights look closer on both gfs and UKMO…

Back end of the eps has an Aleutian low / monster Siberian high + Scandi high /Greenland low combo. The SPV doesn’t want that pattern to verify. Coldies do. Perhaps with a slight adjustment in the Atlantic to get that low to disrupt under the block… we can have our cake and eat it?

Google Scholar SCHOLAR.GOOGLE.COM Have a look through this Feb. Backs up what you’re saying that a full progression from p3-8 at decent amplitude often precedes SSWs. I personally feel that the ideal trop config is a strong scandi-Greenland dipole, followed by high amp p6/7. Much like we had in Jan 18. The west based -NAO / Scandi trough we have now does the reverse (perhaps why we are seeing a strong uptick in SPV strength in the coming weeks). Also there looks to be a significant +EAMT event over the next week or so, these often precede SSWs but no sign of one in the next 3/4 weeks at least. Original post: https://community.netweather.tv/topic/98087-model-output-discussion-the-cold-has-arrived/?do=findComment&comment=4765411

Google Scholar SCHOLAR.GOOGLE.COM Have a look through this Feb. Backs up what you’re saying that a full progression from p3-8 at decent amplitude often precedes SSWs. I personally feel that the ideal trop config is a strong scandi-Greenland dipole, followed by high amp p6/7. Much like we had in Jan 18. The west based -NAO / Scandi trough we have now does the reverse (perhaps why we are seeing a strong uptick in SPV strength in the coming weeks). Also there looks to be a significant +EAMT event over the next week or so, these often precede SSWs but no sign of one in the next 3/4 weeks at least.