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Bring Back1962-63

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Bring Back1962-63 last won the day on December 31 2018

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About Bring Back1962-63

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    Bring Back 1962-63

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    Male
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    Exmouth 65m (212ft) asl
  • Interests
    Everything weather related; glaciation; coin collecting; cricket; bridge
  • Weather Preferences
    Extremes - especially cold and snow

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  1. Thanks for that Knocker! I stand corrected on that specific point. The breakaway LP did indeed form on the surface occlusion as can be seen on this evenings charts:. This morning's fax chart (below) for 0600 tomorrow did not pick up on this feature - always difficult to nail down this type of detail, especially in this set up. The position of the upper occlusion has also changed and very likely has changed again since this chart was prepared. Let's also look at forecast fax for 12 noon tomorrow: The main LP is predicted to move in Biscay and the surface occlusion is predicted to be pivoting southwards in the south west Channel and slightly north westwards in the Southern North Sea. This finer detail may well be slightly changed by the morning, especially if another minor feature develops on the occlusion. Meanwhile the snow continues to fall steadily here in Exmouth.. More later this evening. David 🙂
  2. I agree with you 100% as usual James 🙂 Some on here are looking at misleading information and making erroneous comments - I understand the excitement/disappointment etc. The snow area has actually been expanding (not contracting). Most models did NOT forecast the the breakaway LP forming on the upper occlusion ahead of the main LP which now may be spawning another break away feature or is becoming even more east/west and pivoting/elongating. This is a highly complex set up and is continuously evolving. On the current NetWx I should be under rain but here in Exmouth, I'm less than a mile inland and at a modest 65m and it has been snowing for several hours now, often quite heavily. It has now settled on all surfaces - about 1 cm on the road and pavements and well over 2 cm on the cars and grass. It looks set to continue on and off for much of the next 12 hours. Live Pressure (UK chart is GMT and NW France chart is GMT + 1 hour): Watch that LP as it should move eastwards or north eastwards. It sucks down the cold air from the north and maintains the precipitation. I believe that another small centre may form (or is already forming) off Land's End - the main centre is still over 200 miles to the west of Land's End. The surface occlusion is likely to pulse north and south several times along these mini features. The upper occlusion is roughly along the line of heaviest snow (red/deep pink on the radar) east to west from mid Surrey westwards to north east Devon. The clearance in the west has stalled as part of the snow area returns south westwards. It is uncertain how much northward impetus there will be from the current occlusion, the breakaway feature, any new feature developing or even the main LP but a fair amount of lighter snow has already pushed into the south west Midlands and south east Wales. The winds are increasingly backing towards the east north east and the few remaining less cold areas like the IOW will see their temps falling quite soon and join in the fun quite soon (IMO). David 🙂
  3. Heavy snow startng to settle here in Exmouth and dipped to 0c. Let me cheer you up - the Isle of Wight may be right in the sweet spot within 2 hours. The minor LP that developed ahead of the main system will be right over you by then (just to the south). Current pressure: Then Aperge picks it up nicely: The breakaway LP swings eastwards. Just south of the IOW and you'll be sucking in the cold air from the north. Your current 4c will be 0c or below within 2 to 3 hours (if not sooner). All the southern coastal areas will benefit from this "unusual" feature. For those further north - note the main LP is still expected to swing into the Channel and likely to push the snow further north - difficult to say how far but the occlusion will be close to us overnight and into tomorrow morning - so plenty of time yet. The current clearance from the west is also temporary and snow is likely to spread back southwestwards behind the breakaway feature and ahead of the main LP. All that has happened is that we have "seemingly" a little bonus 3 to 6 hours ahead of the main event. The two snow areas may well combine for a few hours as well. A complicated set up that needs to be monitored. Temps falling generally now Dew points are fine and surface (ground) temps are likely to remain in the 0c to 2c range for most of us (not shown).. David 🙂
  4. The cold air is undercutting steadily from the north due to the minor trough ahead of the main system. This is excellent news. In Exmouth we were 6c at 1500, 5c at 1600 and 2c now at 1640 and the rain has turned to sleet. Charts below. Note that the NW France view is 1 hour ahead of us.
  5. I can see the reason why west Cornwall cooled down much earlier than expected. A little trough of LP developed just ahead of the main system and has turned the winds easterly just there. Note the rotation down there and further south west with "off-shore" north easterlies in the extreme south west and east south easterlies developing further east too - a few hours ahead of schedule. I'm not sure if this feature will develop any further but it's certainly increasing the snow potential in Cornwall and Devon. Check out the development over the last 24 hours. David 🙂
  6. Spot on James. Those will be dragged in this afternoon on the southerlies and then the winds back to off-shore and game on this evening for many of us. I haven't time to repeat all the charts but here's a link to my early morning post (now buried on page 138) where the live pressure, temp and radar charts are all auto updating: https://www.netweather.tv/forum/topic/90939-south-west-and-central-southern-england-regional-weather-discussion-01122018-onwards/?do=findComment&comment=3997547 To add to that - here are the dew points: Live 24 hours to 1248 In my early post, I was referring to the wind backing during today and becoming "off-shore" this evening - a really key ingredient: For around now = south south east For later this evening = east north east Will any snow settle? Yes! The penetrating frost last night means that sub surface temps (down to around 5 to 10 cm) fell well below freezing. The surface temps over most of our region will be 1c to 2c for most of the next 24 hours. Any moderate snow will settle quite quickly. Those that have quite a bit of rain beforehand will see it become slushy and then white. It's a falacy that "wet ground prevents snow from settling" . The surface and immediate sub surface temps are key + the 2M temps + the dew points + the rate of snowfall. Overall, things do not seem to be quite as marginal as I thought that they might be only a day ago. The conditions this evening and overnight look conducive for settling snow providing the LP and the occlusion behave themselves. Finally Friday's 0600 MetO Fax chart: Note the leading occluded front that has stalled over southern England. I call this a "ghost" front as they are white on the map. This is the northern boundary of the less cold air but not at the surface. It has climbed over the cold air which is also providing a nice undercut. The less cold air at the surface is marked by the standard (black) occluded front which is then over the french coast and the southern English Channel. No more time but it's looking pretty encouraging. David 🙂
  7. This is 100% correct. The margins and temp contrasts over short distances will be very high today. This is roughly what we can expect: The less cold air will "initially" be driven inland by the "onshore" southerliy wind - into much of Cornwall, south Devon and south Dorset - it was -4.5c here at 0600 but it's now +5.0c with a few spots of rain! The LP is tracking south eastwards and the warm sector (or less cold air south of the occlusion) will slide away southwards and south eastwards. The winds will back from south through south east to east by mid afternoon and then east north east by this evening and then we'll have "offshore" winds with no moderation from the warm seas. Areas that warmed up to +4c to +7c should see temps plunge later today as the cold air returns south westwards. The rain will "probably" turn to sleet and then snow over much of the southern coastal areas of our region (and say up to 30 miles inland) - later this afternoon and through this evening. Those further north and east will see the precipitation a little later and some will only see snow (esp at altitude of 100m +) and others may see a snow/rain/snow sequence. By mid evening, it looks like all the precipitation will be falling as snow - with potential for heavy falls and decent accumulations even on low ground nearer to the coast. There's a good chance that the snow will hang around or reinvigorate tomorrow morning. The main message is to follow the "nowcasts" and not to be too worried with some early rain and temporarily less cold conditions. David 🙂
  8. Today and tomorrow will be fascinating for a our region in terms of how much snow any of us will see. The set up is really a near nowcast situation with very small changes in the track of the LP and position of the frontal band being critical. I'll show the overnight, current and "live" charts (the live charts "should" auto update every 10 minutes - you may need to refresh the page). It's currently -4.5c here and -6c at Exeter airport (0600). Euro Pressure - 24 hours to 0600 Pressure at 0620 Live Pressure Temps - 24 hours to 0600 SW Temps as at 0600 Live Temps Live Radar Live Satelitte David 🙂
  9. Good morning everyone. Quite a few of us have seen snow showers overnight. Even down here in Exmouth it has settled - a decent dusting. David 🙂
  10. It looks like we are nearly there! What to look for in the models I've still very little time to produce a full post, so I'll do a summary. I'm writing this report for several threads on two weather forums (US and UK) with a full spectrum of readers - so I'll use simple terms. There have been some excellent posts on here in recent weeks and this post will pick up on the timing and coupling issues. Despite the great advances in our understanding of the teleconnections and how they influence the atmosphere and the broad scale patterns, there are still challenges at certain times in understanding how they interact with each other, constructively or destructively and which ones dominate at particular times. The GSDM (global synoptic dynamic model) pulls this together and gives us a great heads up into what is going on and what we "might" expect and look out for in the coming weeks, months and seasons. It's just as important to understand what can go wrong and why as it is when everything goes according to plan. This winter has been both truly fascinating and (so far) pretty frustrating for the cold and snow brigade. We know that a major SSW (sudden stratospheric warming) and particularly a split SPV (stratospheric polar vortex) usually leads to widespread HLB (high latitude blocking) in the Arctic with a lot of cold displaced towards the middle latitudes. No two SSWs are alike. Occasionally the wind reversals in the strat never down well to the trop (troposphere), to influence the surface patterns. More often they do produce surface impacts but this can be pretty quickly (in just one or two weeks) or after a protracted period. These timing issues are mostly in relation to the "coupling" between the strat and the trop. When they are in harmony, down welling can proceed much more smoothly. Since the 2018 SSW and the final warming in the Spring, the strat and trop have been pretty decoupled. In fact, it is this which has delayed and prevented (so far) a full El Nino from developing despite a number of attempts and this has defied most of the main ENSO forecasts. We have seen short periods of El Nino like conditions but with brief La Nina like setbacks. This SSW started off in late December as a displaced SPV which quickly split in early January. The wind reversals in the middle and lower strat lasted for most of this month. There is a recovery underway up there now (which does not mean that the event is over - far from it) and the reversals are at last down welling through the trop. It looks like full surface impacts will be seen in the high Arctic within a week or so. We still need the trop to be receptive (with other teleconnections acting constructively) and it was back in late December but far less so for much of January but the next cycle of tropical forcing has been underway during the last few days. This is where +ve GLAAM (global atmospheric momentum) anomalies push polewards from the tropics. We saw +ve mountain torque events and the GWO (global wind oscillation) is in a higher orbit in phase 6. GLAAM and the torques are key parts of the GSDM. Another part of this forcing mechanism is shown by the MJO (Madden Julian Oscillation) with areas of tropical convection progressing from west to east. This too is entering key phases in its cycle which are more favourable for HLB. In fact ECM has now joined GEFS (and several other models) with increased amplitude from phase 6 into phase 7 within a few days (indicated on both the VP200 and RMM charts). There are the usual time lags and the benefits from both the GWO and MJO in favourable phases are usually seen some 7 to 10 days later - ie: on this occasion very much in harmony with the Arctic surface impacts. There are still two mores ingredients. One of these is the ENSO state with weak El Nino conditions considered to be most favourable for tropical forcing. A WWB (westerly wind burst) is underway in the western tropical Pacific and progressing steadily eastwards. This will be associated with an upturn in the Nino region temperatures which is just getting underway right now. The final ingredient is FT (frictional torque) which has been stubbornly -ve all month - in fact it was last +ve at the equator and northern tropics in late December. FT has been rising for the last 3 or 4 days and on the Jan 24th chart (always produced 2 days afterward) it was heading towards +ve territory and is probably already there. +ve FT really assists with the tropical forcing (caused by the stresses created by tropical convection and changes in AAM). It should help with the strat/trop coupling down there which may well see this El Nino event finally get over the line with a sustained period of Nino conditions as well as contributing to the overall poleward push of momentum. So, it looks like all this is finally occurring with a much greater degree of harmony. The AO (Arctic oscillation) is already going -ve and should go more strongly -ve next week with HP showing up near the pole. The PNA (Pacific North American oscillation) is also going +ve with the Aleutian LP setting up. The down stream pattern of ridges and blocks then develops in conjunction with the forced extensive HLB from the Arctic. The Canadian PV should weaken and be pushed further south. HP is likely to rise in the Greenland area. Siberian, Arctic and Scandinavian HPs should all be seen at stages and the NAO (North Atlantic oscillation) should at last go -ve. For Europe and the UK an extended period of north easterlies or easterlies are favoured. The current LPs with increasingly polar maritime and Arctic incursions in it should be forced southwards or south eastwards. Given the long SSW event in the strat,, we can expect these surface conditions to dominate for much of February and perhaps well into March too. Eastern CONUS and Canada should see even more extensive and prolonged cold. Just how much snow any of us see will be decided closer to the events but all of us should see a fair amount of it. So, once again, I've been very bullish. I do hope that we do not see another "curve ball" - but this time it does look like our patience will be fully rewarded. Those with model fatigue need to recharge their batteries. We can expect the models to pick up on these imminent changes increasingly during the next few runs. In fact therehas already been a shift. UKMO looks to be the most progressive with D6 Arctic blocking (and consistent with their extended outlook). Exciting times ahead. David 🙂
  11. It looks like we are nearly there! What to look for in the models I've still very little time to produce a full post, so I'll do a summary. I'm writing this report for several threads on two weather forums (US and UK) with a full spectrum of readers - so I'll use simple terms. There have been some excellent posts on here in recent weeks and this post will pick up on the timing and coupling issues. Despite the great advances in our understanding of the teleconnections and how they influence the atmosphere and the broad scale patterns, there are still challenges at certain times in understanding how they interact with each other, constructively or destructively and which ones dominate at particular times. The GSDM (global synoptic dynamic model) pulls this together and gives us a great heads up into what is going on and what we "might" expect and look out for in the coming weeks, months and seasons. It's just as important to understand what can go wrong and why as it is when everything goes according to plan. This winter has been both truly fascinating and (so far) pretty frustrating for the cold and snow brigade. We know that a major SSW (sudden stratospheric warming) and particularly a split SPV (stratospheric polar vortex) usually leads to widespread HLB (high latitude blocking) in the Arctic with a lot of cold displaced towards the middle latitudes. No two SSWs are alike. Occasionally the wind reversals in the strat never down well to the trop (troposphere), to influence the surface patterns. More often they do produce surface impacts but this can be pretty quickly (in just one or two weeks) or after a protracted period. These timing issues are mostly in relation to the "coupling" between the strat and the trop. When they are in harmony, down welling can proceed much more smoothly. Since the 2018 SSW and the final warming in the Spring, the strat and trop have been pretty decoupled. In fact, it is this which has delayed and prevented (so far) a full El Nino from developing despite a number of attempts and this has defied most of the main ENSO forecasts. We have seen short periods of El Nino like conditions but with brief La Nina like setbacks. This SSW started off in late December as a displaced SPV which quickly split in early January. The wind reversals in the middle and lower strat lasted for most of this month. There is a recovery underway up there now (which does not mean that the event is over - far from it) and the reversals are at last down welling through the trop. It looks like full surface impacts will be seen in the high Arctic within a week or so. We still need the trop to be receptive (with other teleconnections acting constructively) and it was back in late December but far less so for much of January but the next cycle of tropical forcing has been underway during the last few days. This is where +ve GLAAM (global atmospheric momentum) anomalies push polewards from the tropics. We saw +ve mountain torque events and the GWO (global wind oscillation) is in a higher orbit in phase 6. GLAAM and the torques are key parts of the GSDM. Another part of this forcing mechanism is shown by the MJO (Madden Julian Oscillation) with areas of tropical convection progressing from west to east. This too is entering key phases in its cycle which are more favourable for HLB. In fact ECM has now joined GEFS (and several other models) with increased amplitude from phase 6 into phase 7 within a few days (indicated on both the VP200 and RMM charts). There are the usual time lags and the benefits from both the GWO and MJO in favourable phases are usually seen some 7 to 10 days later - ie: on this occasion very much in harmony with the Arctic surface impacts. There are still two mores ingredients. One of these is the ENSO state with weak El Nino conditions considered to be most favourable for tropical forcing. A WWB (westerly wind burst) is underway in the western tropical Pacific and progressing steadily eastwards. This will be associated with an upturn in the Nino region temperatures which is just getting underway right now. The final ingredient is FT (frictional torque) which has been stubbornly -ve all month - in fact it was last +ve at the equator and northern tropics in late December. FT has been rising for the last 3 or 4 days and on the Jan 24th chart (always produced 2 days afterward) it was heading towards +ve territory and is probably already there. +ve FT really assists with the tropical forcing (caused by the stresses created by tropical convection and changes in AAM). It should help with the strat/trop coupling down there which may well see this El Nino event finally get over the line with a sustained period of Nino conditions as well as contributing to the overall poleward push of momentum. So, it looks like all this is finally occurring with a much greater degree of harmony. The AO (Arctic oscillation) is already going -ve and should go more strongly -ve next week with HP showing up near the pole. The PNA (Pacific North American oscillation) is also going +ve with the Aleutian LP setting up. The down stream pattern of ridges and blocks then develops in conjunction with the forced extensive HLB from the Arctic. The Canadian PV should weaken and be pushed further south. HP is likely to rise in the Greenland area. Siberian, Arctic and Scandinavian HPs should all be seen at stages and the NAO (North Atlantic oscillation) should at last go -ve. For Europe and the UK an extended period of north easterlies or easterlies are favoured. The current LPs with increasingly polar maritime and Arctic incursions in it should be forced southwards or south eastwards. Given the long SSW event in the strat,, we can expect these surface conditions to dominate for much of February and perhaps well into March too. Eastern CONUS and Canada should see even more extensive and prolonged cold. Just how much snow any of us see will be decided closer to the events but all of us should see a fair amount of it. So, once again, I've been very bullish. I do hope that we do not see another "curve ball" - but this time it does look like our patience will be fully rewarded. Those with model fatigue need to recharge their batteries. We can expect the models to pick up on these imminent changes increasingly during the next few runs. In fact there has already been a shift. UKMO looks to be the most progressive with D6 Arctic blocking (and consistent with their extended outlook). Exciting times ahead. David 🙂
  12. At last we have what we've been predicting - a poleward surge in +ve AAM. Another important piece in the jigsaw for Arctic blocking: The relative GLAAM tendency anomaly has spiked upwards and looks set to reach its highest level of the winter. Global MT is surging upwards and both NAMT and EAMT are strongly +ve too. The GWO has already looped back into phase 5 and is set to go into a much higher orbit through phases 5, 6 and 7. This is the strong tropical forcing that we've been saying is needed to assist the down welling in the stratosphere. So far, I believe that the models have just begun to sniff out the SSW surface impacts. They usually struggle to pick up on the tropical forcing. So we go from a pretty destructive phase into a really constructive one. In the mid term (say day 10 onwards but perhaps sooner and remember that these charts have a 2 day output time lag) this should hugely assist with the HLB patterns. I would expect the models to start picking up on this over the next few days but with various blocking outcomes and solutions. A CAUTIONARY NOTE: We still need to monitor how the jet stream phasing in the Pacific behaves and this has impacts on the US storm system(s) and a knock on down stream in the Atlantic. This may or not not be favourable in the short term but given the prolonged SSW event, the strength of the MT spikes and poleward momentum the opportunity is likely to persist for many days (or weeks).  Continued exciting model watching for the rest of this month and beyond. No more time this week. David 🙂
  13. Wonderful pics Malcolm - on the first one (above), from your apartment, just below the peaks in the centre, it looks like the edge of a snowfield or glacier overhang and avalanche danger from there, I hope that goes behind the ridge and doesn't endanger your village. I've done a close up below. When you get such extreme volumes of snow, even areas not normally at risk can be. Please be careful but continue to enjoy it all. Really giving me the hunger for a good dumping back here. David 🙂
  14. Very brief comments from me as no time until the end of the week. Great to see much better looking output and obviously the much more +ve mood that goes with it. Some excellent posts too with some well thought through analyses. I just wanted to make a few comments on the change in the output. Assuming that the models are starting to sniff out the wind reversals and down welling to the surface near the pole and that actually transpire, then I'll refer to what often happens when SSWs start to take hold - especially split events (and the displaced/split event that we're seeing does in that respect rather match 2013 and perhaps it will for longevity too - many differences in detail too). I'll leave that bit to our strat specialists. This is so different to what we are normally looking for. As some of us have been saying, the HP builds over the pole. When it really takes hold and the full reversal occurs (hopefully it's still just a case of timing) it becomes the dominating feature. It displaces the TPV and even stubborn looking patterns can be displaced amazingly rapidly. We are staring to see a variety of solutions showing up in how we get from the current set up into a cold and blocked regime. I actually feel that we'll see any easterly much sooner in this process than much of the output is suggesting (some not at all "yet") - perhaps around Jan 25th-30th, assuming that the rough target date remains near Jan 20th (may still be further delays). Before you think, how can I say this, let me briefly explain. I could pick from quite a few ens charts but the GEM solution is well on the way to what I want to show: As many charts are showing to various degrees, we have the HP building over the pole. The PV has already split at the surface by day 8 and more so on this day 10 chart). The Euro lobe is being pushed down towards eastern Scandinavia and central/northern Europe and on its way to central/southern Europe. The Canadian lobe will weaken and we really do not need to get hung up about it. The LP over and to the east of us by then already contains some fairly cold Arctic air in its circulation. The Arctic HP is likely to initially ridge southwards - just imagine all that Arctic cold air being forced out by the polar easterlies and displaced towards the mid latitudes. Some models have it linking up with the Atlantic ridge and a stronger northerly but again that's not important as I believe that this is only transient. Not a topler to let the Atlantic in - quite the reverse. The LP over us continues to track east south eastwards.and the Euro lobe continues on its way south. Then the key bit which has happened so many times in these SSW scenarios - pressure builds strongly and rapidly over the top of the Euro lobe. From the north and/or the north east. GEM have strong HP building from Russia towards the Arctic. Before you know it a strong Scandi HP is building. We might see small variants on this with a Scandi/iceland HP or even the ultimate prize of a Scandi/Siberian HP. Once in place this type of pattern can become entrenched. Once established, at times the HP can retrogress towards Greenland and allow a real Arctic blast but the easterly or north easterly is usually back quite quickly afterwards and that's, as we know, is likely to deliver our deepest cold. I saw several comments that it doesn't look that cold (surface and 850s) on some of the otherwise promising charts and the ones which have deeper cold cannot be believed. This is deep Arctic cold being ejected and it now seems very likely that some (or perhaps a lot) of it has the UK's name on it. Once this change is underway, it's likely to fall into place really quickly. Overall, we still need to watch the down welling, the reversal, the final evolution and the timing of it all but something along the lines I've suggested is IMHO quite a likely scenario. Back around Friday - David 🙂 EDIT: I see that ECM is not far off this evolution too - perhaps a day or two behind
  15. MY CURRENT VIEWS ON THE MODELS AND THE OUTLOOK That was a great post @Kirkcaldy Weather and should be read by all those who are moaning about the output. I have very little time now or for a few days - so rather than show loads of charts, I'll make a few bullet point statements on the background signals, the model output and several general comments. No two SSWs are alike - I do not know how many times that has to be said. In my last two posts I tried to show what to look out for with comparisons to the current set up and charts with the 2018 and 2013 SSWs (part 3 on 2009 with likenesses and differences to 2019 to follow by next weekend). What those archived charts showed was just how quickly the HLB patterns developed and the whole northern hemisphere set up changed and evolved. I noted John's @johnholmes comments this morning wrt examining archived "forecast" charts prior to earlier SSW events - something I suggested too - they're available for most of the models now and certainly the big 3. John also queried whether or which previous SSWs had failed to deliver any significant cold here in the UK. I'll just repeat a table here: We know that 2018 and 2013 delivered big time and they were split SSW events (2013 displaced and then split) and so did 2008//09 and 2009/10 both also split. The last displaced SSW was in 2007/08 and I believe that can be considered a failure but for that and earlier events, we need to check the archives - and I haven't got time for that but anyone can go by the table above and check the archive charts for the whole SSW period. Here's the link again: http://www.meteociel.fr/modeles/archives/archives.php?mode=2&month=1&day=20&year=2008&map=4&type=ncep I set it to Jan 20th 2008 to get you started. We can take comfort in the fact that most (perhaps almost all) split SSWs have produced decent periods of HLB which have delivered cold to the UK. The teleconnections have NOT let us down at all and contrary to what the usual suspects might be saying through their impatience. In fact they are almost spot on in terms of what we expected from them - there's a slight problem over precise timing but that's always the case with SSWs and such dramatic pattern changes (which the models cannot handle). The next three comments were confirmed to me by @Tamaraby PM and I hope she doesn't mind my referring to them as she will continue to avoid this thread with all the confrontation and I fully sympathise with her (our loss). The tropical/extra tropical cycle and forcing has been sufficient to amplify the tropospheric pattern and it's just that the polar field has not "yet" been conducive for HLB and stratospheric dimuition. She thinks that in January 2013 the tropopause was more receptive at this stage than it has been so far this time. She feels that "its still barely into the second week of January and there is far too much overreaction in general". Back to my own comments: That means in both directions - no cold patterns showing or a Siberian wasteland - we're somewhere in the middle right now. We've a substantial split event ongoing and the best news is that this SSW seems likely to be very protracted, perhaps approaching the 2013 record length and some records are already being achieved up there. We should have at least two or three bites at the cherry. The lagged impacts of the MJO through phases 6, 7 and now into 8 may show up within the next 7 to 10 days - favouring HLB. I see that for once the GEFS (bias corrected version) and the ECM are both in broad agreement for a change (long may that last but do not hold your breath) and week 2 MJO forecasts and notoriously unreliable.. Although they dive into the COD soon, they both look set to re-emerge in phase 6 and maybe for a quick "rinse and repeat" through phases 6, 7, 8 and 1 again in early Feb.(perhaps later). Something to keep an eye on for sure. The lagged effects of the GWO in phases 5 and 6, albeit at slightly weaker AAM than we had expected is still strong enough to have +ve impacts for the next two weeks. This cycle is likely to repeat in or by early Feb too. The temporary weakening in the El Nino seems to be over and it looks sets to strengthen again - a better tropical state with a weak Nino - gentle forcing but not too strong like the 2015 super Nino.. Meanwhile, the SPV destruction continues and may take many days, weeks or perhaps not at all to reform into a more organised fashion. Overall - an exceptional and truly fascinating period for all the atmospheric processes with an extremely high chance of cold patterns setting up later this month and perhaps for much of February too.. We are about to see a transition to a less settled phase but this is probably a sign that there are changes to feed through from the Arctic and towards the mid latitudes - merely timing issues IMHO. Looking at the models, I see that a good number of ensemble members show charts which develop HLB blocking patterns - some as early as day 7/8 and building on the Arctic outbreak, others do this later on in the run. If you study those charts from 2018 and 2013 and indeed some other pre/during/post split SSW events, you'll see that the initial impacts can almost always be seen close to the pole. Several GEFS ens show a "yellow" HP - a strong sign of a full reversal reaching the surface. Some show heights building towards a proper Greenland HP and some towards Scandinavia. Do not worry about the TPV still looking immovable on our side of the Arctic. What should happen is as (when - not if IMHO) the wind reversals reach the surface is that those low heights are displaced southwards - almost bulldozed out of the way. Quite often a lobe drops into Scandi and it "looks" like we'll see a true northerly but that would likely be short-lived and transitory but not the normal "toppler type" either. What happens is that HP builds around the top of the LP and pushes that south into central and southern Europe. Then that opens the pathway for Siberian and Russian heights to push westwards (which occurred in dramatic fashion to create the "Beast" last Feb/Mar.). Although easterlies have been a rarity in the last 30 years they were much more common back in the '60s to '80s and even mild winters saw several outbreaks. Those associated with SSWs are usually very potent. Then the HP can build towards Iceland and Greenland letting in a true Arctic air stream with north to north east winds - many of our coldest winters see an easterly/northerly combo. When will all this happen? I'm very confident of "this" winter and well before Spring. No guarantees - there never can be but the current set up is on the verge of something quite dramatic. Frankly, with the strat state as it is and taking account of the other teleconnections, I'll be astounded if we do not see a memorable cold spell in much of Europe, the UK and eastern CONUS, eastern Canada as well as large parts of Asia/Russia/Siberia - not all at the same time but we should all see periods of extended wintry weather. So, please, please be patient and accept that the models will struggle - which I and others have been saying for a while and I've shown that there has been a slight delay - not for weeks on end!. When I'm on here again at the end of this week, I hope that we can all be focusing on some much more attractive output in the mid term. David 🙂
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