Eagle Eye

I realised that I didn't really specificy timescales on my last post except my Christmas end which based off the progression of the zonal pattern might be a bit too progressive. Signs that we're moving towards the phase 2/3 pattern of the MJO but those affects probably won't be felt until at least the new year considering that's around the time the AO finally comes out of negative. So I'm going to extend my cold deadline to the new year. Its a genuine possibility that there will be cold opportunities for all of this month. The main affects towards the middle to the end of the month might not be driven by the MJO (yes it will be helped of course) but by the East Asian reaction to the jet retraction amplifying wave centres hence increasing Rossby Wave transfer via the synoptic wave train. That would henceforth create that Scandinavian block or somewhere near there through downstream interactions. The recovery of the jet retraction is interesting to me as well but I discussed that earlier as well. Original post: https://community.netweather.tv/topic/98087-model-output-discussion-the-cold-has-arrived/?do=findComment&comment=4757365

I realised that I didn't really specificy timescales on my last post except my Christmas end which based off the progression of the zonal pattern might be a bit too progressive. Signs that we're moving towards the phase 2/3 pattern of the MJO but those affects probably won't be felt until at least the new year considering that's around the time the AO finally comes out of negative. So I'm going to extend my cold deadline to the new year. Its a genuine possibility that there will be cold opportunities for all of this month. The main affects towards the middle to the end of the month might not be driven by the MJO (yes it will be helped of course) but by the East Asian reaction to the jet retraction amplifying wave centres hence increasing Rossby Wave transfer via the synoptic wave train. That would henceforth create that Scandinavian block or somewhere near there through downstream interactions. The recovery of the jet retraction is interesting to me as well but I discussed that earlier as well.

It's way too early to tell but I suppose it's possible, patterns do tend to repeat and there is the early signal for it but right now it's still a small signal. I'm being wary of calling either way as we would the MJO repeating pattern as an early signal for that and I simply wouldn't know yet. Its a possibility that we could be stuck in a consistent -VE AAM but it's also a possibility that we see a re-transferring of thermal states back to a +VE AAM as the AAM is still fairly nuetral either way so little MJO variations can have a big difference. I'll research more when I get home from school though .

The dynamical recovery of the AO probably has a lot to do with the unstable inertia that has propped up the -VE AO state losing it's support with a loss of AAM and therefore the Eddy's 'retreating' across the Northern Hemisphere battlefield as the Rossby energy transfer retreats to being mostly across the tropics with a flatter Atlantic to probably come into place by early next year. Signs that we could get an increase again in January but for now I'd treat it as signs. The GWO supporting my view of the jet coming into line with the thermal wave northward transfer (of the jet momentum so the jet reverts back to normal) and eventual pattern flip into circumglobal ridges and it's been a general trend recently. Circumglobal ridges linked with Atlantic influence and mild and wet. So beyond Christmas things may return back to normal with the occasional colder chance but I keep saying it... Take this chance on the face of it and it is the best early Winter chance since 2010, as simple as that, we've still got till Christmas before any chance of severe cold setting in goes and even beyond then we don't know for sure that we won't get helpful background influences. Original post: https://community.netweather.tv/topic/98087-model-output-discussion-the-cold-has-arrived/?do=findComment&comment=4757081

The dynamical recovery of the AO probably has a lot to do with the unstable inertia that has propped up the -VE AO state losing it's support with a loss of AAM and therefore the Eddy's 'retreating' across the Northern Hemisphere battlefield as the Rossby energy transfer retreats to being mostly across the tropics with a flatter Atlantic to probably come into place by early next year. Signs that we could get an increase again in January but for now I'd treat it as signs. The GWO supporting my view of the jet coming into line with the thermal wave northward transfer (of the jet momentum so the jet reverts back to normal) and eventual pattern flip into circumglobal ridges and it's been a general trend recently. Circumglobal ridges linked with Atlantic influence and mild and wet. So beyond Christmas things may return back to normal with the occasional colder chance but I keep saying it... Take this chance on the face of it and it is the best early Winter chance since 2010, as simple as that, we've still got till Christmas before any chance of severe cold setting in goes and even beyond then we don't know for sure that we won't get helpful background influences.

"Later on into the day on Tuesday (Day 6), continued eastward advance of the deep upper cyclone, and an occluding surface low over the Nebraska vicinity, is expected. As the cold front continues eastward across the southern Plains and into the Ozarks/Arklatex, high theta-e low-level air and modest heating should yield ample CAPE -- particularly across Louisiana and into Arkansas during the afternoon. With a very strong/veering flow field with height that should prove quite supportive of severe/supercell storms, risk for tornadoes is apparent, along with damaging winds and hail. This risk will shift gradually eastward in tandem with frontal advance, likely crossing into the Mississippi and western Tennessee vicinity into the overnight hours."

The jet 'recovery' across East Asia is about to begin, reloading the Pacific jet wave and PNA back to more neutral territory which may reload the Atlantic long-term and wane the Greenland block. Although, it may just change the basing of the Greenland block into a more west based block it's hard to tell just from any composites I could find. Hence forth we still see a slightly -VE NAO on about half of the ensembles despite the recovery of the AO that seems fairly likely on most. I do think this will increase the zonal westerlies beyond Christmas but that doesn't mean we can't see long term cold up until then with the -VE EAMT interacting with the lag of the +VE AAM looking pattern with an amplified North African wave potentially forming a UK and/or Scandinavian blocking and helping the -VE AO pattern slightly mid-term. The recovery of the AO can be expected eventually though as the Troposphere transfers energy through regressing Eddy's. We simply cannot keep up the -VE AO and eventually the pattern will collapse but most importantly right now, the pattern is expected to keep steady(ish) for the mid-term and we've seen a recent trend towards longer term cold on about half the runs. A lot relies on a lot of different things but there's decent support for a more substantial cold spell to keep going and importantly, the trend on most of the recent days has been an increasing number of support for the longer-term (ish) cold and fairly substantial cold. I would keep up the positivity for now because we've got a lot to be positive about. Compared to recent Decembers this simply outweighs every other December (in my opinion) for snow and cold potential since 2010. Worrying about precipitation isn't worth it considering the time scale especially because in years before we were looking for anything that supported colder trends yet this year we're getting that cold and people are now over-anlaysing. I can understand why though. It's a real shame that for all of the year's this could have happened, it had to have happened in a year with a significant energy crisis as well. Despite the timeframe of this it shows how good of a setup up we are within relative to recent years: No one can guarantee you 3 foot snowdrifts in your back garden and if they could, they would be lying but they can say that there is chance of you seeing decent snowfall compared to anything really since around 2018 (especially away from Scotland) and to take this as it comes because looking into the distant FI won't solve anything (I know I used it there but that's on the GEFS ensembles and to demonstrate my point rather than analyse anything). Original post: https://community.netweather.tv/topic/98064-model-output-discussion-3122022-how-cold-will-it-get/?do=findComment&comment=4756979

The jet 'recovery' across East Asia is about to begin, reloading the Pacific jet wave and PNA back to more neutral territory which may reload the Atlantic long-term and wane the Greenland block. Although, it may just change the basing of the Greenland block into a more west based block it's hard to tell just from any composites I could find. Hence forth we still see a slightly -VE NAO on about half of the ensembles despite the recovery of the AO that seems fairly likely on most. I do think this will increase the zonal westerlies beyond Christmas but that doesn't mean we can't see long term cold up until then with the -VE EAMT interacting with the lag of the +VE AAM looking pattern with an amplified North African wave potentially forming a UK and/or Scandinavian blocking and helping the -VE AO pattern slightly mid-term. The recovery of the AO can be expected eventually though as the Troposphere transfers energy through regressing Eddy's. We simply cannot keep up the -VE AO and eventually the pattern will collapse but most importantly right now, the pattern is expected to keep steady(ish) for the mid-term and we've seen a recent trend towards longer term cold on about half the runs. A lot relies on a lot of different things but there's decent support for a more substantial cold spell to keep going and importantly, the trend on most of the recent days has been an increasing number of support for the longer-term (ish) cold and fairly substantial cold. I would keep up the positivity for now because we've got a lot to be positive about. Compared to recent Decembers this simply outweighs every other December (in my opinion) for snow and cold potential since 2010. Worrying about precipitation isn't worth it considering the time scale especially because in years before we were looking for anything that supported colder trends yet this year we're getting that cold and people are now over-anlaysing. I can understand why though. It's a real shame that for all of the year's this could have happened, it had to have happened in a year with a significant energy crisis as well. Despite the timeframe of this it shows how good of a setup up we are within relative to recent years: No one can guarantee you 3 foot snowdrifts in your back garden and if they could, they would be lying but they can say that there is chance of you seeing decent snowfall compared to anything really since around 2018 (especially away from Scotland) and to take this as it comes because looking into the distant FI won't solve anything (I know I used it there but that's on the GEFS ensembles and to demonstrate my point rather than analyse anything).

The jet recovery across East Asia is about to begin, reloading the Pacific jet wave and PNA back to more neutral territory which may reload the Atlantic and wane the Greenland block or it may just change the basing of the Greenland block into a more west based block and hence forth we still see a slightly -VE NAO on about half of the ensembles despite the recovery of the AO. I do think this will increase the zonal westerlies beyond Christmas but that doesn't mean we can't see long term cold up until then with the -VE EAMT reloading a +AAM looking pattern with a amplified North African wave potentially forming aa UK and/or Scandinavian blocking and reloading the -VE AO pattern slightly down the line. The recovery of the AO can be expected as the Troposphere transfers energy through regressing Eddy's. Decreasing the SSW chance down the line with less vertical energy transfer as we re-enter a more steady-state atmosphere. The AAM and GWO supports my idea of a more zonal outlook eventually with a transfer to a steady -VE AAM state and a more loaded Atlantic beyond Christmas, perhaps supported by the PNA pattern looking increasingly zonal right towards the end of it's run. We see the largest initial decrease seemingly due to a negative mountain torque event over the coming days and northwards momentum transport should recover the Atlantic jet and eventually we should move into circumglobally ridges and a milder pattern with some frontal low's with drag from Canada as a more zonal profile suggests. So as we go into late December, things look to be becoming more zonal with a typical mild and wet pattern unless we see a SSW through a riding outer wave in the Stratosphere in the coming weeks that could reverse the Stratospheric zonal wind. Main way of cold beyond Christmas would be through the reversal of the typical Stratospheric profile. The GFS shows increased pressure on the Stratosphere but how those warmings interact and/or evolve is going to have a big effect. That riding outer wave on the right probably has the best chance of increased pressure on the North Pacific Stratosphere or the European Stratospheric profiling. It's clear that we'll see an increase in Wave-1 dominance around the 11th onwards and so we'll be looking for increased pressure on the Stratosphere through that outer riding wave split rather than a full contraction of the Stratosphere which would also split it. The 4 main wave-1 Stratospheric profiles show that we could see the outer wave 'push' the Arctic jet away from it's initial position and therefore the zonal wind weakens and shrivels. We could also see the wave have little effect on the profile depending on the wave strength. It could also see it displace it but towards where the Siberian wave is on the chart a little bit above. Then we could also see another, slightly different, little effect on the Stratospheric profiling and therefore zonal wind.

Yes normally we see it have a meltdown

The moisture feed coming up from the south has weakened a bit as the general trend and its become more stretched with no real Convective centre forecast so it may act a little more like a normal low pressure system it's just where it is that's messing with everything a lot.

Lovely morning but a bit cold . Already been a crash

I'm just finding it fun watching the Hurricane models try and make sense of invest - 99L. Marvelling at the feat's we've made to understand Hurricanes but also how far we've got to go to truly understand. HRWF HMON This post isn't really meant to evaluate everything just proving that one of the pinnacles of physical modelling still has far to go to stop 'minor mistakes' and we all have seen that minor differences make big differences down the line.

This post is not directed at anyone in particular by the way... It's very tense, run up to potential deep cold and people start worrying about every nitty gritty detail that doesn't need to be worried about (works both ways as well). Everyone needs to keep in mind that 1 run doesn't continue a trend, 2 runs don't either. There's a reason the professionals will 99% of the time make the best forecast, a trend especially beyond 120 hours, is best seen on the same run over a couple days (e.g the 06Z over 3-5 days) and it helps to see the bigger picture. Weather moves quite slowly synoptically and so this way works and avoids a lot of the drama, also avoiding over ramping apart from our own biases. That is why the Met Office should mostly be the primary source of information for forecasts (in my opinion, although trends can be spotted on this forum before they see it occasionally) as they don't ramp nor do they actually downplay and that's what a lot of people miss. The know their stuff. Sure, you can note key features on each run but don't get over worried on it. I understand the excitement for a certain run though, passion gets to 99% of us and it's understandable, I've made that mistake many a time. This forum probably won't change significantly but hopefully we can stop over analysing every single detail and instead see the overall pattern. Right now, we are in a brilliant pattern but it's high risk, hence why the tension is increasing as we get to crunch time but take a break, take yourself out for a bit and relax. I've taken myself out from looking at the models except the 00Z/06Z for the last few days and it's so much easier to see that the pattern is slowly moving but far from swinging either way yet.

Time for my typical talk about my friends. Unfortunately my best friend Georgie has had someone in her family die and so has been to the funeral this week, she's holding strong in normal life but I hope she's got support from her family especially because losing a family member always will have a profound effect on you. On the other hand, hopefully the weather can cheer her up as she is a true coldie at heart so no pressure on the weather right now. Whereas for my so called 'crush' Olivia hates the cold (only ginger ever I think who does) so I've been trying my best to play this down to her as I don't want to be the deliverer of bad news, I've been buying her favourite food for her even though she never asks me because I feel sorry for her with it getting colder. Any other year and she'd be happy as I would say the outlook was mild and wet but of course this one December especially with the energy crisis is looking to be quite cold. She loves Ed Sheeran and I've just found out that you can get his signed stuff for really cheap on Ebay (I don't know why, the signed stuff is from his last album as well) so that's either Christmas or her birthday sorted . Then my friend Charlie that quite likes any weather that isn't boring, he especially likes snow though so I've constantly been drumming up the channel low and the long term cold pattern as I'm, placing all my trust in the retracted East Asian jet amplifying the Scandinavian ridge downstream. So I'm going to look like a bad forecaster to one of my friends and so I'll have to point out that there were so many different options that I could realistically please all with my forecasts (although I'm still telling Olivia it's going to be cold short term) but only 1 of the different options is going to be wrong. Good luck to all, let's see how this plays out...

How many times does it have to be said. At this range, looking at precipitation charts is essentially useless. I don't really think I need to say the same thing that has been said a hundred times as to why.

Thank you, I've never really had the best knowledge of the intricacies of a SSW just a general overview. That's the one thing that reading documents can't give you, I guess I'll be able to understand this more with experience.

What looks most likely at the moment is a slow move to zonal with a loss of mountain torque but we wouldn't see those effects slowly kick in till around or beyond Christmas time. It's only 1 run and goes significantly against the other GWO runs so I would suggest that it could still be quite wrong. I think we'll still see a loss initially as you would expect but that doesn't mean we cant see a quick switch to positive torque and an increasing AAM. Still a lot of possibilities in the air beyond mid month. Im not going to stress too much over it for now, the GWO varies a lot. Not to mention the continuing possibility of a SSW with fluctuating Eddy's propagating vertically into a fairly weak Stratospheric zonal wind as we aren't seeing a rapid zonal wind increase yet especially in the lower Stratosphere. The bottom-up split route looks to be the most likely way at the moment.

I wouldn't be surprised, me and a few others touted it as a possibility ( @chionomaniac first I think) for many different reasons with a decent number of background signals and dynamic trends supporting it. The combination of a shortwave moving into Europe on quite a few runs later on, the East Asian jet retraction amplifying things downstream and the Eurasian feedback of the.-VE East Asian Mountain Torque (EAMT) has meant that its a possibility going into the next couple weeks.

My mid-term forecast has not changed much from yesterday. On the ensemble mean, clear signs that the energy scattered from the -VE EAMT downstream amplifies the -VE to +VE PNA transition phase, amplifying the jet oscillations through the Atlantic eventually. Especially affecting the high off the coast of North Africa hence the UK and/or Scandinavian blocking in the mid-term potential. Although the jet recovery profile in East Asia looks to be quite strong so I think a more zonal setup long-term may be possible going into the new year but of course that jet recovery hasn't fully happened yet.

Oh interesting, I was of the idea that the GFS was right that we're moving away from phases 6 and 7 especially but I forgot to account that it still has a lot of scatter and the ECM is moving back towards those two 'best' phases, I probably should have mentioned that more specifically.

Jet retraction across East Asia amplifying downstream waving and increasing the effects of any potential troughs just North and/or West of the African high on the block with amplified thermal gradient. As long as cold develops over the Scandinavian region, me thinks the potential Scandinavian blocking regime could help collapse that cold with increased pressure on the cold from the North and South, high risk, high reward situationmay develop. The -VE AO holding pattern helped by the unstable inertia of the lag of the +VE AAM and MJO may start to wane though. As well as that the Eurasian feedback will probably start to fall due to the recovery of the -VE EAMT nd dissipate energy into potentially stretching the jet beyond(it could also amplify downstream events and get the PNA into a +VE pattern which has its own effects but I think it'll just level off the PNA and so we cannot really rely on the roughly 14 days on and we get American weather theory). So the exact timing of the downstream effects may matter quite a lot. We could see help from a shortwave colliding into the North African (ish) High increasing amplification with the rotational force applied potentially pushing it up Eurasian feedback could still be going strong +VE AAM at the time of the potential event is the most likely AAM Scandinavian(maybe UK) blocking is the most likely form of block A delay may mean the Eurasian feedback wanes The MJO phase forecasts are moving away from recycling phases 6 and 7 We could see increased Atlantic effects from the East Asian jet retraction still. -VE AO cannot hold itself forever So its best that the downstream effects occur sooner rather than later and there's probably about a 50/50 chance but it means that this may not be the only chance of severe cold. Away from the -VE EAMT effects downstream and... For me, this upcoming prolonged chance is far from anything with too much flip flopping. As always, the development of shortwaves is difficult to decipher from each model run and how it affects the mid term onwards is therefore up for a lot of speculation. Add the uncertainty of the mid Atlantic subtropical (extratropical?) development and the uncertainty that comes with it and its no wonder there's no real solution as of yet.

31st most trending video on YouTube the Met Office forecast . We're still at the point where we're looking for prolonged cold being a genuine opportunity that we're taking away from the initial cold, instead looking at the breakdown despite the fact that it's a while away. Just the fact that prolonged cold is a fairly good possibility makes this the best early Winter chance for a long time.

I don't know if this has been posted here before but here's what the NOAA have said about the development. "A large non-tropical area of low pressure located over the central subtropical Atlantic about 800 miles northeast of the northern Leeward Islands continues to produce a large area of disorganized showers and thunderstorms. Environmental conditions appear marginally conducive for development and a subtropical or tropical storm could form within the next day or two. By Thursday night or early Friday, the low will move northeastward over cooler waters and interact with a mid-latitude trough, limiting the chance for additional subtropical or tropical development of the system." vs yesterday's 00Z, 06Z, 12Z and 18Z ensembles (00Z hasnt been added yet for today) for the track. Up until 168 hours for each run. Clearly nothing is set in stone yet.

I'm going to sign off for tonight as I don't have much to add to the conversation for now, I am of the firm belief that the jet retraction across East Asia and the energy scattering across the Pacific and North America will eventually have consequences down the line but I've discussed that in detail before. Might go into more detail tomorrow to further explain my point as to why it might be a long term driver of the AO signal but I won't talk about it for now as its getting late.