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stodge

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About stodge

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    Mr Stodge

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  1. Morning all :) Given lying snow is possible in London until the end of March, far too early to completely give up on seeing the white stuff. GFS 06Z OP teases at a trough disrupting SE in early March with -8 uppers transient in the east which would be good enough for something wintry I'd imagine. As per usual, there is no height rise to the NE so the jet shifts back north and the Atlantic rolls back in. Plenty of signs that, relative to the coming weekend, temperatures will be much lower in early March though hardly exceptional and more like a return to average from well above average. We often see this conflict between colder and warmer air masses in March as the atmosphere evolves from its winter state. Also just to note a hint of the slightest of warmings from the North American side into FI - not a meaningful Wave 1 but I wonder if it could displace the PV to Siberia with all that flows.
  2. Morning all πŸ™‚ It does look as though, as IDO so thoroughly explains, any attempt to retrogress heights to the NW at the turn of the month looks to be on a very temporary basis. The 00Z GFS OP soon brings back a vigorous Atlantic but more than a hint of the jet heading south as we move into March - not unusual in itself as this is when the battle between the colder and warmer airmasses which heralds spring takes place. It may be the faux spring we are enjoying now will be a false dawn as we move into March. The Parallel is less inspiring though both models build significant heights across the Pole - the OP almost flushes all the energy out of the Canadian PV.
  3. stodge

    North American Weather (U.S.A & Canada)

    Definitely a cold spell for some: https://eu.desertsun.com/story/news/2019/02/16/record-cold-weather-streak-palm-springs-80-degrees/2891379002/
  4. Isn`t the problem that when we get the trough disrupt into Europe, we aren`t seeing consequential height rises over Scandinavia so the pattern flattens each time.
  5. Yes, I stand corrected on that. I recalled two particularly cold spells but I'm sure later February was quite mile verging on warm. As you say, the overall numbers were on the cold side - I was just trying to tease out if there was any linkage to this notion of the winter before a minimum being not desperately cold or even mild.
  6. Afternoon all πŸ™‚ I added the below to the general Winter 2018-19 Thread yesterday but I think it belongs here: Part of my working life revolves around post-event analysis and I always approach these projects with two questions in mind: 1) What Happened and Why Did It Happen? - this is 95% of the time and it's quite boring because you have all the information and it's not terribly difficult to ascertain a pattern or sequence of events. 2) What Should Have Happened and Why Did It Not? - this is the really interesting 5% and clients trying to work out what went wrong rarely start from here. It's amazing how often people expect something to happen and are completely flummoxed when it doesn't. A confirmatory mindset takes over and they repeat the same event, get the same result and start wondering what has gone wrong. Anyone seeking to analyse Winter 2018-19 for the UK should start with the second question. Nick F's blog this morning is a superb analysis of the first part of the first question though as with all of us enthusiastic amateurs the "why" requires more information than to which we have access. It's disconcerting to see organisations such as ECM and UKMO with access to far larger information resources and infinitely more sophisticated and detailed computer modelling still get it wrong but at the same time mildly encouraging for those who like to think there are mysteries still to be solved. I'm left with four discordant and possibly unrelated observations as I try to fathom the questions above: 1) Where has all the Fog Gone? - whether caused by AGW or not, the thought I had this morning was another winter has gone by with barely any morning fog. If I were in the physics game, I'd be wondering whether a warmer world creates more energy in the atmosphere making for a more mobile atmospheric environment. More energy in the atmosphere might mean a stronger PV with all that flows (so to speak) from that. I'd love to know what the PV looked like in the mediaeval warm period or during the late 17th Century. Did it exist? Is it where it is now? Did it behave as it does now? It is such a crucial part of the pattern especially as it draws intensely cold air down into North America and encourages cyclogenesis and fires up the Atlantic jet. 2) When is an SSW not an SSW? - it's now clear the SSW of January 2019 was a very different creature from the SSW of February 2018. The latter was akin to the flushing of a toilet with hot water - this swept down the atmosphere shredding the PV and allowing the cold air to flow down (and more importantly the warmer air to flow up), Within less than 3 weeks from the actual vortex split, we were looking at a significant cold outbreak. We were told then (and indeed at the New Year) not all SSWs work favourably for NW Europe and this one obviously hasn't. I'm less convinced what we saw wasn't an actual SSW but a very strong Wave 1 displacement. These, as we know, usually come from the Eurasian side and shunt the PV lobe back to the Canadian side. They rarely do us any favours apart from as a cumulative effect weakening and destabilising the PV. We rarely get a warming from the Canadian side (I believe the 62-63 cold spell originated with a Canadian Warming) and it's worth asking why these don't happen. Even now there's no sign of another Wave 1 and while the PV is weakening as we head to month end the comparison with 2018 is incredible. Oddly enough, the best recent comparison is with 2013 - yes, I know. 3) Don't Drink The Water - one or two individuals who were less bullish about the winter than many cited the Atlantic SSTs as a factor behind their caution and after this winter's forecasting debacle it's worth considering this. Are we seeing as was postulated in a certain movie glacial meltwater entering the ocean and lowering the temperature? I'm not convinced but at a time of generally warming oceans parts of the Atlantic remain cold: https://www.ospo.noaa.gov/data/sst/anomaly/2019/anomnight.2.11.2019.gif Curiously, we are now seeing some quite warm water off the eastern seaboard of CONUS so I wonder if that explains why the Atlantic LP are slowing and deepening? It's one to keep an eye on and an indicator worth revisiting for further analysis. 4) It's the Sun, Stupid - a final thought occurred when doing some reading and I picked up a comment that the winter immediately prior to a solar minimum is often mild in north west Europe. No explanation as to why this should be and I'm not convinced the analysis tells a good story as the Modern Maximum was a huge event but we still got some very cold winters (I'm still wondering if that was related to sulphur dioxide emissions). Clearly, the Maunder and Dalton Minimums were significant periods for colder winters but the 11-year cycle is relevant. Looking at winter 2008-09 there were two significant cold spells but overall it was fairly mild. IF this is valid, it may be the proponents of a cold winter were simply a year too early with both 2019-20 and 2020-21 looking much better. That said, will this minimum be as strong as the 2009-10 Minimum? It will need to be to deliver the cold and snow many on here want. As the song says, there are "more questions than answers" and I don't have a lot of the latter. I appreciate the angst of the young bears but there's no need to rail against forecasters, climatologists or each other. If you want to understand the weather better, start learning about it. NW has plenty of information as a starting point.
  7. Afternoon all πŸ™‚ Worth repeating - periods of warmth in February are far from unknown. This one "might" break some records but we'll have to see if the SSE'ly flow delivers next week. This is however the Hunt for Cold thread - NOT the Hunt for Cold in Winter thread - and while it's probably correct to say there's little prospect of anything cold before the end of February (and therefore the end of winter as many reckon it) it's certainly NOT the end of the road for cold conditions. I've experienced 21C in March as recently as 2017 and yet last year it was very different. That's March - often a month of contrasts and in four of the last ten years I've seen lying snow in lowland East London. So, snow can lay in March in London and further north and higher up through April as well so the Hunt very much goes on. The current pattern with the deep mid-Atlantic trough is far from helpful and none of the models are offering anything for cold fans as we go into the first days of March but there's a lot of time for things to change. That doesn't mean the next change will favour cold - it's more likely we'll see a return to a more mobile pattern - but that's the thing, there's always another change down the road.
  8. Evening all πŸ™‚ After the awful morning runs, the 12Z output much better going forward with a strong signal for anticyclonic conditions becoming established in the last week of the month and approaching the turn of the month. Position and orientation of the HP a very long way from being resolved but possibilities for frost and that long-missed item, fog. Don't worry about the 850s if we go get an inversion regime - it's a pity we aren't seeing this in mid December. Could we get the HP to the north or east - certainly options on the table at this stage.
  9. stodge

    Winter 2018/19

    Afternoon all πŸ™‚ Rather than put my thoughts in the Cold Rampers thread which is now a bearpit full of angry young bears upset they've had no snow, we'll try the hopefully more refined waters of this thread. Part of my working life revolves around post-event analysis and I always approach these projects with two questions in mind: 1) What Happened and Why Did It Happen? - this is 95% of the time and it's quite boring because you have all the information and it's not terribly difficult to ascertain a pattern or sequence of events. 2) What Should Have Happened and Why Did It Not? - this is the really interesting 5% and clients trying to work out what went wrong rarely start from here. It's amazing how often people expect something to happen and are completely flummoxed when it doesn't. A confirmatory mindset takes over and they repeat the same event, get the same result and start wondering what has gone wrong. Anyone seeking to analyse Winter 2018-19 for the UK should start with the second question. Nick F's blog this morning is a superb analysis of the first part of the first question though as with all of us enthusiastic amateurs the "why" requires more information than to which we have access. It's disconcerting to see organisations such as ECM and UKMO with access to far larger information resources and infinitely more sophisticated and detailed computer modelling still get it wrong but at the same time mildly encouraging for those who like to think there are mysteries still to be solved. I'm left with four discordant and possibly unrelated observations as I try to fathom the questions above: 1) Where has all the Fog Gone? - whether caused by AGW or not, the thought I had this morning was another winter has gone by with barely any morning fog. If I were in the physics game, I'd be wondering whether a warmer world creates more energy in the atmosphere making for a more mobile atmospheric environment. More energy in the atmosphere might mean a stronger PV with all that flows (so to speak) from that. I'd love to know what the PV looked like in the mediaeval warm period or during the late 17th Century. Did it exist? Is it where it is now? Did it behave as it does now? It is such a crucial part of the pattern especially as it draws intensely cold air down into North America and encourages cyclogenesis and fires up the Atlantic jet. 2) When is an SSW not an SSW? - it's now clear the SSW of January 2019 was a very different creature from the SSW of February 2018. The latter was akin to the flushing of a toilet with hot water - this swept down the atmosphere shredding the PV and allowing the cold air to flow down (and more importantly the warmer air to flow up), Within less than 3 weeks from the actual vortex split, we were looking at a significant cold outbreak. We were told then (and indeed at the New Year) not all SSWs work favourably for NW Europe and this one obviously hasn't. I'm less convinced what we saw wasn't an actual SSW but a very strong Wave 1 displacement. These, as we know, usually come from the Eurasian side and shunt the PV lobe back to the Canadian side. They rarely do us any favours apart from as a cumulative effect weakening and destabilising the PV. We rarely get a warming from the Canadian side (I believe the 62-63 cold spell originated with a Canadian Warming) and it's worth asking why these don't happen. Even now there's no sign of another Wave 1 and while the PV is weakening as we head to month end the comparison with 2018 is incredible. Oddly enough, the best recent comparison is with 2013 - yes, I know. 3) Don't Drink The Water - one or two individuals who were less bullish about the winter than many cited the Atlantic SSTs as a factor behind their caution and after this winter's forecasting debacle it's worth considering this. Are we seeing as was postulated in a certain movie glacial meltwater entering the ocean and lowering the temperature? I'm not convinced but at a time of generally warming oceans parts of the Atlantic remain cold: https://www.ospo.noaa.gov/data/sst/anomaly/2019/anomnight.2.11.2019.gif Curiously, we are now seeing some quite warm water off the eastern seaboard of CONUS so I wonder if that explains why the Atlantic LP are slowing and deepening ? It's one to keep an eye on and an indicator worth revisiting for further analysis. 4) It's the Sun, Stupid - a final thought occurred when doing some reading and I picked up a comment that the winter immediately prior to a solar minimum is often mild in north west Europe. No explanation as to why this should be and I'm not convinced the analysis tells a good story as the Modern Maximum was a huge event but we still got some very cold winters (I'm still wondering if that was related to sulphur dioxide emissions). Clearly, the Maunder and Dalton Minimums were significant periods for colder winters but the 11-year cycle is relevant. Looking at winter 2008-09 there were two significant cold spells but overall it was fairly mild. IF this is valid, it may be the proponents of a cold winter were simply a year too early with both 2019-20 and 2020-21 looking much better. That said, will this minimum be as strong as the 2009-10 Minimum? It will need to be to deliver the cold and snow many on here want. As the song says, there are "more questions than answers" and I don't have a lot of the latter. I appreciate the angst of the young bears but there's no need to rail against forecasters, climatologists or each other. If you want to understand the weather better, start learning about it. NW has plenty of information as a starting point.
  10. Have to say I thought the Control would be a warm outlier but the OP on the cold side. Interesting to see some colder options than the OP out there. All to play for with the Mean splitting the difference and ending up near average.
  11. Morning all πŸ™‚ Having stepped away from the models for nearly a week back in this morning to see where we are or aren't. As others have said, a lot remains unresolved after this weekend's storm and the brief Arctic incursion. As the HP builds behind it, can it ridge fully into Scandinavia or does it get stuck somewhere between the Thames Estuary and the Baltic? ECM 0Z OP gets there in the end but on the second attempt next weekend with the first HP heading ESE into western Russia so a settled week but fairly mild at first trending colder (it is still mid February so fog and frost obvious factors). The GFS 00Z OP (and on GFS everything happens so quickly) gets the HP to Scandinavia but a full retrogression to Greenland is broken by a small LP in the SW approaches which breaks the link and we quickly return to stormy and mild conditions. The 06Z OP sends the LP SE into Iberia and it all ends extremely well for coldies as the forces of evil march in triumph across all parts of the British Isles especially the far SW. GEM 00Z OP simply doesn't want to know - even though the PV has largely drained toward Siberia by T+240, a succession of vigorous LP engaged presumably by the cold air over Canada fire across the Atlantic so there's no chance of a ridge. JMA 12Z yesterday was cold weather porn and we'll see if it follows up today. NAVGEM 06Z (I've always liked NAVGEM, it probably verifies worst of the major models but there you go) ends next Friday with the HP over southern Scandinavia but the orientation and NH profile doesn't suggest retrogression as a likely option. UKMO doesn't go out far enough to take a definitive view. GFS 06Z Parallel hasn't quite finished but a cell of HP detaches from Greenland and drops SE over the British Isles so plenty of cold air in that you'd think but a likely sinker as well. The 06Z Control is horrible for cold fans as the LP train doesn't stop and the PV is draining back into Canada from Siberia so we masters of evil had better hope that's an outlier. Interesting to read some comments suggesting the downwelling is still going on and may not reach the troposphere until the 20th which would be extraordinary if correct. Further up, the PV is where you'd expect it to be in mid February in all honesty. So there seem to be two very divergent options on the table starting from what happens with the initial push of HP after this weekend. Option A: The HP fails to ridge north but remains around Germany or Denmark before sliding away east or south-east as the Atlantic energy flattens it and we return, after a brief mild and settled spell, to a mild and unsettled spell. Option B1: The HP ridges into Scandinavia and the Atlantic slows enough to allow the trough to disrupt SE and retrogression to take place with a much colder airlow between east and north becoming established as pressure falls over Europe, Option B2: The HP ridges into Scandinavia but there is too much energy in the jet to allow full retrogression to take place. Instead, the HP holds firm between the North Sea and Scandinavia and we settle into a settled but colder and cloudier flow from the east.
  12. Evening all πŸ™‚ Interesting to see the variation between the main models at T+144: UKMO: GEM: GFS OP: GFS Parallel: ECM: UKMO is the slowest with everything - the LP is still over the British Isles and the LP is heading north over the eastern seaboard and into Canada thereby offering a greater chance of promoting the mid-Atlantic ridge or of lifting heights NE from the Azores into Scandinavia. The key is the secondary LP which the UKMO develops and sends across the British isles next Monday - GEM hints at it but it's not on GFS or ECM which has the LP already well clear of the country and the next LP able to begin to move across the Atlantic and flatten the ridge. The delay also allows a wedge of heights to try and develop over eastern Greenland (hinted at on GEM and to an extent ECM).
  13. Evening all πŸ™‚ It seems as of February 2nd, the inquests are already being written on winter 2018/19 which is extraordinary but inevitable especially for those who expected some snow (and were disappointed) in the past 48-72 hours. As a reflection of my own, I suspect what we are calling a SSW was in fact a very strong Wave 1 displacement. Originating from the Eurasian side, it didn't so much split the PV as fragment it leaving a residual lobe over the Canadian side which. as often happens with Wave 1 events, became smaller but stronger and thus we had in early and mid January a 10-14 day period of mild conditions. As to the downwelling, my limited physics suggests it equates to a form of percolation. As the pressure of the downwelling increased, all it did was to increase resistance further down in the troposphere making the PV more not less resilient. Now, if those who follow these things are correct, the downwelling should reach the troposphere next week but the models aren't interested or it's having no effect as all we see in the short and medium term is something we've not seen a lot of this winter and that's a spell of Atlantic-dominated weather. The PV, which some had predicted would be displaced west, seems firm in its desire to remain between Greenland and Canada. There's very little for fans of cold to hold on to in the short and medium term - a 10-14 day spell of milder Atlantic weather looks locked in and perhaps the thought that some much needed rain now may stave off problems were we to have another hot summer is perhaps a crumb of comfort. Beyond mid month is an eternity away - the 12Z GEFS had plenty of members looking to build heights through NW Europe from the south and east - the 12Z Parallel ends about as positively as it can for a cold weather fan but it's so far away it can hardly be relied on. It's entirely possible this Atlantic spell will carry through this month and into March before we get the right ingredients for amplification but that seems to be contrary to a lot of signals so I'm far from convinced winter is "over" by any stretch and recent experience should tell us all March can be a cold and snowy month and even here in lowland London snow can fall and lay until the end of March. There will be plenty of signals in the next 7-14 days suggesting spring is at hand but we've seen so many of these "false springs" before it's strange to see people getting sucked in again. It may be a good time (unless you're interested in stormy conditions) to look away from the models (if you can) for a week and come back this time next week and see if the trend for a post mid-month pattern change is still being signalled.
  14. Afternoon all πŸ™‚ Away from the snow angst in the regional discussions and back to something more sensible and some thoughts on the medium to longer term evolution going towards the middle of the month and beyond. A couple of days ago we were being teased with height raises to the NE as the PV weakened and displaced and the Atlantic amplified. However, the GFS 06Z OP is relentlessly Atlantic throughout albeit with signs of the jet coming south in FI - mainly mild but changeable and getting stormier toward mid month. Little hope for cold on the Parallel either - if anything, a milder and more vigorous Atlantic but a sign at the very edge of FI of some amplification upstream over North America allowing heights to build over NW Europe. Control keeps a wedge of heights to the north so the jet is further south but even with the PV pushed over to Siberia the Atlantic still fires up again in FI and it goes stormy into mid month. Looking at the GEFS, the signal for northern blocking isn't dead by any means but is much weaker (perhaps 6 out of 20 by T+300 offering some solution with blocking to the north or east). Elsewhere, the 00Z ECM ends with a weak ridge building north to the west of the British Isles but it's a curious evolution. The end of the 06Z NAVGEM raised an eyebrow. CFS 00Z makes fools of those thinking winter is over with a re-run (not quite) of a very cold and wintry end to February and beginning of March. So, it seems the prospect of any HP to the east has been swept away and atypically the first half of February is looking quite disturbed with a dominant jet and powerful Atlantic. Perhaps around mid month it gets stormier as the jet eases south but the second half of the month is far from clear and those thinking today and tomorrow mark the end of winter may yet be in for a surprise.
  15. Afternoon all πŸ™‚ Obviously a lot of disappointed people on the snow front in this region but also a few winners as well. Clearly, for those furthest to the east and south the orientation of the LP ushered in a sector of more humid air caused a steady if not rapid melt of snow cover and some quite hefty rain showers down over east Kent. It reminded me of December 2010 when the Saturday snowfall was attacked by a pulse of humid air on Monday which brought a little rain and a melt of about half of what was lying. As with others, here in lowland East London, we had a little snow as the front came through but by dawn this had largely melted and now we have quite steady rain and a temperature of around 2c but humidity up around 90% so very marginal but just the wrong way for me. Some indications of a brief re-invigoration of the front as it pulls away to the south and south east overnight so whether that will equate to a dusting by morning remains to be seen. Tomorrow does look a cold feeling day with 850s of -6 or so for much of the day and lower humidity but we'll be under a transient ridge by then. The end of winter? Who knows? Still one third to go by most reckoning and perfectly possible even here to have lying snow well into March.
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