Eagle Eye

This was me a couple minutes ago. I think I've gone loopy. 20221211_143318881_001_001.mp4

I think we'll get some snow, the timing is much better than previously on the models as to when it advects so that natural cooling within the air parcels its associated with can take place. Evaporative cooling cools that air parcel further but warms the air around it hence the strongest precipitation should come as snow with the highest area of convection. If we take a sounding from the GFS it's fairly borderline but Ibthink its overdoing the temperature profiling just ever so slightly and there may be more of a temperature difference with height and there may be more vorticity driving up the precipitation than even the hi red models can see I would think and the gravity waves not being accounted flr could.mean areas of quite heavy snow may form along a cold upper profiling with a cool dewpoint, in more specific areas.

Thats the spirit... To be fair, I think you're correct here, clear signs that the trough's on either side are bringing in warmer dewpoints but by the evening nightfall, I expect we'll see a cooling of the temperatures and a dropping off of the dewpoints. The placement of the trough will be important later as it may cause a slight WAA with evaporative cooling in areas so a mix of rain, maybe freezing rain, sleet and snow with the close to freezing dewpoints meaning quite the mix.

Overdoes convection in the summer possibly more to do with overcompensating the dewpoint into higher values, which should be less of a problem here, I think it generally overdoes convection as well but less so in Winter, let's see how this goes...

Quoting myself from the model thread "The downstream effects of the East Asian jet retraction interest me. We're into the time where we can see the clear amplification of Rossby thermal transfer cropping up on the models in a fairly reliable time although exact handling will be very off at this point. The effects on how Eddy's are handled may be negative but the generalised conception of increasing Eddy Heat Flux especially in the upper Troposphere may be slightly better handled than usual. Usually , this would probably increase the -VE AO but we're in such a -VE AO dip that it may just delay the recovery of the AO through the formation of that UK and/or Scandinavian blocking signal that's starting to persist on the models. It's still too far out to worry about localised dynamics of the high but the signal is showing for the blocking to form and of course how it forms will affect the short term gain at that time but as long as the wandered blocking pattern keeps up the relative pattern flip cold throat should exist. I think up until very late December potentially later than that, this pattern may be able to keep itself going synoptically hence the cold chance probably persists till around early January. Then we've got the potential MJO influence helping us into the second week of January (effects would be later on) and that may happily coincide with another energy scattering PNA cycle. Me thinks the scattering of energy interacting with the more southerly based jet will drift up hot air from North Africa which may cause some areas of Europe to see ridiculously mild air for this time of year and probably not something you associate so close to a quite significant -VE AO pattern. Just using 1 model run to show what I mean is probably not a good idea at the time range that I'm talking about and it goes against my principals but I'm just using it to show the mild air that could possibly be drawn up. It's very unlikely to look anything like that but it does show what could be drawn up by the energy and amplification scattering interacting with the high just off the coast of North Africa. A very interesting thing as we go closer to time I think but we still can't be sure that the North African (ish) High will be interacted with nor the direction that its drawn up so we could end up seeing one extreme or the other. Looking more into the short term future... Initial pulses of colder air in a cold pattern and maybe the formation of a shortwave or something similar that could still end up dumping a decent amount of snow somewhere, then... Cold air that would normally look blocked in fairly well seems to get thwarted to the south and a pulse of amplification correlated with the downstream effects of the PNA pattern (correlated with the East Asian jet retraction fairly well, funny how everything links together) but how long it stays for is hard to tell for now. There is a chance it could just be a mild blip and that it goes on to prop up the -VE AO pattern as discussed earlier. Or it could hold itself in for longer and set itself in for a longer time, for now I just don't know and its fairly evenly balanced."

Was going to say it sounds like graupel to me but have changed my mind when I realised "looks like rain", maybe freezing rain but I have no idea what freezing rain is to be honest.

I do agree with you but was trying to see the positive side of things (especially after the England match) and these patterns could repeat (however unlikely). I think the main help though will be through the GWO which looks like it could repeat a +VE frictional or mountain torque phase and we see another wave train scattering energy downstream. Of course this is in FI for now but I wouldn't be surprised if we saw it, just may be a bit more delayed than my initial post states.

Signs on the ECM extended that we may be moving towards a repeating pattern with a fairly mobile MJO trying it's best to keep moving towards phases 5-8 and hence the increases 6 and/or 7 chance as well. So a potential repeating pattern on the cards as we go into the early/mid January period after a short zonal dip. For now, Im going to leave that alone though and let it be FI but let's hope it becomes a repeating trend. If it does then this Winter COULD end up being like 'the old Winters' but I'm not going to ramp yet, instead, all I'm going to say is that it doesn't guarantee a -VE NAO, just increases the chances and its still too far out that we can't be sure of anything yet. The downstream effects of the East Asian jet retraction interest me. We're into the time where we can see the clear amplification of Rossby thermal transfer cropping up on the models in a fairly reliable time although exact handling will be very off at this point. The effects on how Eddy's are handled may be negative but the generalised conception of increasing Eddy Heat Flux especially in the upper Troposphere may be slightly better handled than usual. Usually , this would probably increase the -VE AO but we're in such a -VE AO dip that it may just delay the recovery of the AO through the formation of that UK and/or Scandinavian blocking signal that's starting to persist on the models. It's still too far out to worry about localised dynamics of the high but the signal is showing for the blocking to form and of course how it forms will affect the short term gain at that time but as long as the wandered blocking pattern keeps up the relative pattern flip cold throat should exist. I think up until very late December potentially later than that, this pattern may be able to keep itself going synoptically hence the cold chance probably persists till around early January. Then we've got the potential MJO influence and that may happily coincide with another energy scattering PNA cycle. Me thinks the scattering of energy interacting with the more southerly based jet will drift up hot air from North Africa which may cause some areas of Europe to see ridiculously mild air for this time of year and probably not something you associate so close to a quite significant -VE AO pattern. Just using 1 model run to show what I mean is probably not a good idea at the time range that I'm talking about and it goes against my principals but I'm just using it to show the mild air that could possibly be drawn up. It's very unlikely to look anything like that but it does show what could be drawn up by the energy and amplification scattering interacting with the high just off the coast of North Africa. A very interesting thing as we go closer to time I think but we still can't be sure that the North African (ish) High will be interacted with nor the direction that its drawn up so we could end up seeing one extreme or the other. Looking more into the short term future... Initial pulses of colder air in a cold pattern and maybe the formation of a shortwave or something similar that could still end up dumping a decent amount of snow somewhere, then... Cold air that would normally look blocked in fairly well seems to get thwarted to the south and a pulse of amplification correlated with the downstream effects of the PNA pattern (correlated with the East Asian jet retraction fairly well, funny how everything links together) but how long it stays for is hard to tell for now. There is a chance it could just be a mild blip and that it goes on to prop up the -VE AO pattern as discussed earlier. Or it could hold itself in for longer and set itself in for a longer time, for now I just don't know and its fairly evenly balanced. Original post: https://community.netweather.tv/topic/98087-model-output-discussion-the-cold-has-arrived/?do=findComment&comment=4761080

Signs on the ECM extended that we may be moving towards a repeating pattern with a fairly mobile MJO trying it's best to keep moving towards phases 5-8 and hence the increases 6 and/or 7 chance as well. So a potential repeating pattern on the cards as we go into the early/mid January period after a short zonal dip. For now, Im going to leave that alone though and let it be FI but let's hope it becomes a repeating trend. If it does then this Winter COULD end up being like 'the old Winters' but I'm not going to ramp yet, instead, all I'm going to say is that it doesn't guarantee a -VE NAO, just increases the chances and its still too far out that we can't be sure of anything yet. The downstream effects of the East Asian jet retraction interest me. We're into the time where we can see the clear amplification of Rossby thermal transfer cropping up on the models in a fairly reliable time although exact handling will be very off at this point. The effects on how Eddy's are handled may be negative but the generalised conception of increasing Eddy Heat Flux especially in the upper Troposphere may be slightly better handled than usual. Usually , this would probably increase the -VE AO but we're in such a -VE AO dip that it may just delay the recovery of the AO through the formation of that UK and/or Scandinavian blocking signal that's starting to persist on the models. It's still too far out to worry about localised dynamics of the high but the signal is showing for the blocking to form and of course how it forms will affect the short term gain at that time but as long as the wandered blocking pattern keeps up the relative pattern flip cold throat should exist. I think up until very late December potentially later than that, this pattern may be able to keep itself going synoptically hence the cold chance probably persists till around early January. Then we've got the potential MJO influence and that may happily coincide with another energy scattering PNA cycle. Me thinks the scattering of energy interacting with the more southerly based jet will drift up hot air from North Africa which may cause some areas of Europe to see ridiculously mild air for this time of year and probably not something you associate so close to a quite significant -VE AO pattern. Just using 1 model run to show what I mean is probably not a good idea at the time range that I'm talking about and it goes against my principals but I'm just using it to show the mild air that could possibly be drawn up. It's very unlikely to look anything like that but it does show what could be drawn up by the energy and amplification scattering interacting with the high just off the coast of North Africa. A very interesting thing as we go closer to time I think but we still can't be sure that the North African (ish) High will be interacted with nor the direction that its drawn up so we could end up seeing one extreme or the other. Looking more into the short term future... Initial pulses of colder air in a cold pattern and maybe the formation of a shortwave or something similar that could still end up dumping a decent amount of snow somewhere, then... Cold air that would normally look blocked in fairly well seems to get thwarted to the south and a pulse of amplification correlated with the downstream effects of the PNA pattern (correlated with the East Asian jet retraction fairly well, funny how everything links together) but how long it stays for is hard to tell for now. There is a chance it could just be a mild blip and that it goes on to prop up the -VE AO pattern as discussed earlier. Or it could hold itself in for longer and set itself in for a longer time, for now I just don't know and its fairly evenly balanced.

@Cambrian I don't think anyone's comparing it to 2010 in potential, it's more like people are saying it's best chance for December snow (proper) since 2010. GEFS sharing my views on the MJO that we'll have a decent phase 5/6/7/8 lag correlation going into the latter half of December so slightly increased chance of cold when you factor in the slower progression at the moment before an eventual return to the generally more zonal phases 1 and 2 probably by early January.

This Is what the ALARO is showing so not definitely off (obviously first chart is just a general one) just yet.

All agreed that we love the WRF-NMM in the south and the midlands for delivering the snow right?

Plus he knows his stuff. Anyway, it's not like moderating is an exact science, it's very much subjective, having been one once myself, everyone believes they are in the right and it's hard to get a good balance but I think the moderator's have got it basically spot on, on here.

Am in a weird mood tonight so I won't be commenting on the models but let's hope tomorrow morning's runs offer insight (I've jinxed it now ).

Yeah thats fair enough, to be honest I can't remember who's who on twitter anyway, I may be thinking about a different person entirely. To be fair to forecasters getting it wrong nobody can know everything not even the great MattWolves but he sure does know 99% of the stuff.

Everything can change in the morning It's a high risk setup, let's just see how things go...

Cold spell living up to its meaning kn the ECM and beyond... Just 1 run but the background drivers do support it still at that point... Let's hope it becomes a trend and not just a rouge run.

A-level taster day done so I've got time for a look at the weather finally now... GWO continues to revert to a -VE AAM pattern so I think after we see the dynamical downstream effects of the East Asian jet retraction and its recovery and extension, we'll have an increasing chance of zonal Atlantic influence late December/early January. Based off MJO alone and we could see the cold pattern background signals lag correlations lasting right up until late December so the increasing zonal flow probably wouldn't take place till the new year despite the relatively quick dip into -VE AAM. The -VE EAMT and it's recovery have affected the East Asian jet if only for a couple days, significantly dipping the PNA. The surprising strength of the -VE PNA testament to the strength that the short timescale retractng East Asian Jet has upon amplification of the Pacific and North American pressure anomalies and furthering the Rossby wave thermal transfer amplifying waves downstream. I think that'll help slow down the progressivess of the atmosphere and hence the few days delay of the normal MJO cycle effects being felt 10-14 days later (I think). I think it'll also interact with the North African pressure systems and create a UK/Scandinavian blocking as the most likely solution off the back of any Eurasian feedback remnants depending on timing. However, the effects on us specifically will probably depend more on where the blocking is placed so watch this space, we could be in for some further cold if the Scandinavian blocking forms or we could end up with a milder pattern if the pattern takes too long to develop. For now though, the initial initial is starting to settle in with frosts and some snow already. Potential for more snow on the way and then next week, what's in store still is relatively unknown but we could see a few surprises as things don't actually look that bad as maybe a few runs have suggested and the overall pattern of runs is fairly good for coldies. There will more than likely be things that crop up closer to time that could deliver more widespread snow and we may get a good scenario through a proper shortwave/trough interaction. It's all very interesting weather wise going into the next few weeks and we'll see a lot of twists and turns along the way. The game has only just begun. Original post: https://community.netweather.tv/topic/98087-model-output-discussion-the-cold-has-arrived/?do=findComment&comment=4759032

This setup is very much radar watcher, a rash of increased precipitation is easily missed by the models as they aren't high resolution enough to include the gravity waves helping to add vertical 'vorticity' that cause the effects of heavy precipitation in areas that can't be modelled very well. In the Summer this is less of a problem with over estimated dewpoints often and potential vorticity lobes I think are slightly over modelled in the Summer but it's still not great and convergence is another thing that can be missed as well so that's why we can see unmodelled areas of precipitation or undermodelled snow depth charts.

A-level taster day done so I've got time for a look at the weather finally now... GWO continues to revert to a -VE AAM pattern so I think after we see the dynamical downstream effects of the East Asian jet retraction and its recovery and extension, we'll have an increasing chance of zonal Atlantic influence late December/early January. Based off MJO alone and we could see the cold pattern background signals lag correlations lasting right up until late December so the increasing zonal flow probably wouldn't take place till the new year despite the relatively quick dip into -VE AAM. The -VE EAMT and it's recovery have affected the East Asian jet if only for a couple days, significantly dipping the PNA. The surprising strength of the -VE PNA testament to the strength that the short timescale retractng East Asian Jet has upon amplification of the Pacific and North American pressure anomalies and furthering the Rossby wave thermal transfer amplifying waves downstream. I think that'll help slow down the progressivess of the atmosphere and hence the few days delay of the normal MJO cycle effects being felt 10-14 days later (I think). I think it'll also interact with the North African pressure systems and create a UK/Scandinavian blocking as the most likely solution off the back of any Eurasian feedback remnants depending on timing. However, the effects on us specifically will probably depend more on where the blocking is placed so watch this space, we could be in for some further cold if the Scandinavian blocking forms or we could end up with a milder pattern if the pattern takes too long to develop. For now though, the initial initial is starting to settle in with frosts and some snow already. Potential for more snow on the way and then next week, what's in store still is relatively unknown but we could see a few surprises as things don't actually look that bad as maybe a few runs have suggested and the overall pattern of runs is fairly good for coldies. There will more than likely be things that crop up closer to time that could deliver more widespread snow and we may get a good scenario through a proper shortwave/trough interaction. It's all very interesting weather wise going into the next few weeks and we'll see a lot of twists and turns along the way. The game has only just begun.

Having my A-Level taster day today and it looks like we might be having a taster for what could come later this week or next week as well.

Yes, I got that 46 number a couple times but I don't know how because others are saying 7KM, what I don't understand is how there isn't a definitive source somewhere on the Internet, surely someone has done that. I mean, even the sites that are supposed to be government ran talking about the models are out of date, there's not much I could find for every model away from the years 2012 and 2016 for whatever reason.

Exactly, both are ran at a much higher resolution than the GFS and GEM I'm not sure of ECM upgrades since then but the integrated forecasting system... "For high-resolution forecasts (HRES) and ensemble forecasts (ENS) the grid-point resolution is roughly doubled to 9 km and 18 km, respectively" UKMO is around 10KM but I think it depends on the area like the GFS. GEM is 25 KM according to the TWO, 22KM according to Meteologix The GFS I couldn't find much for that's accurate but we know it's a low resolution model and Meteologix says 23KM. Extra resolution according to Meteologix ICON - Roughly 13KM. ARPEGE - roughly 46KM.

Just stay in here (do as I say not as I do) if you want some sort of clarity, glad you managed to get back from the MAD thread in one piece though .

Not necessarily true, depends on the phase the 'Hurricane' is in. For example, a Hurricane with a strengthening tail will follow the upper level flow hence Hurricane Fiona took a more westerly track than initially forecast because that was where the upper-level flow took it. So it really depends on what phase it's in but as a general rule of thumb I'd suggest that you're correct here.