Jump to content


  • Content Count

  • Joined

  • Last visited

  • Days Won


Everything posted by OldMetMan

  1. I've been keeping my head down for a while, with no sign of any "proper" cold showing in the models, by that I mean, a N, NE or E flow. But recent runs of both the GFS and ECM keeping showing variations on an easterly flow, so as I see it now, the prospects look more encouraging than they really have all winter. The shape of the 500mb flow seems to be slowly shifting, with that small polar upper high re-appearing for the first time in a while, plus the amplifying upper trough over and to the W of us. What's been lacking for much of the winter has been HP in higher latitudes, close
  2. On the face of it, the current situation would look perfect for pressure rises to the NE - slack LP field for the first time on ages over Scandinavia, strong upper ridge to our W, LP pushing NE on its NW flank which you'd expect to build the upper ridge and carry surface pressure rises with it. But alas no, well at least not yet. All the really cold air according to the models looks destined for E and SE Europe - just too far away darn it! But this, as espoused by the GFS-Para looks more like it: Now that is how it should be looking now. It'll be interesting to see if that idea p
  3. Some snow fun for some of us tomorrow, with a considerably downscaled LP tracking across us. Although there are model agreements on the developing HP that is predicted for us in the coming days, I can't help but feel that the location of the HP is too far SW and higher pressures look more likely for Scandinavia, and to our N, rather than over us. This would involve a more SW-NE orientation to the associated upper ridge. With so many changes in output models recently, it seems a possibility. With that, of course, a more direct, colder continental flow would happen. As things stand, we are
  4. The models' ambivalence as to what happens on or after Christmas Day continues. The spectacular looking LP for 27th would indeed be interesting, but I guess the chances of anything like it happening at this distance are pretty remote, although having said that, it is a possibility. What I find odd still is that there have been no real signs within the models of a pressure build from the NW after Christmas. Pressure rises to the S or SW yes, but that is all. Several days of cold air coming S across the Norwegian Sea, LP much weaker over Scandinavia, a situation which has in the past given r
  5. The 12Z GEM shows what I had in mind in my last somewhat cryptic post! I would think the LP to the SW might be a little closer and the ridge from Greenland maybe stronger but as the cold air spreads S, the frontal zone would split, with a warm front headed W around that LP. Something similar I remember happened once before at Christmas as cold air pushed the mild Atlantic air away - rain turned to snow on that occasion.
  6. I think both the GFS outputs are suffering from an excess of Christmas spirit. Ah well, no doubt later runs will change it all again. Beyond 4-5 days at the moment with the models is just too silly, so instead I shall look at where we actually are. One thing I found encouraging today is the appearance of a closed upper high north of Iceland. The US ridge is also holding its own and continuing to move E. The wretched upper low over the W Atlantic has finally lifted out. It seems the pivotal moment is around Christmas Eve, as the cold front drifts SE. Is there likely to be a develop
  7. The latest ECM at T240 has that "shape" again - LP strung out across the Atlantic south of 50degN, associated with an extended upper trough aligned E to W. Above this, an upper high stretching from Canada to Greenland, with associated HP. So much depends on cold air extending far enough S, both in terms of its depth and extent. Given enough of a block, and a continuing cold feed down across the Norwegian Sea, LPs in this situation will run NE and glance off the cold block, until finally one runs far enough SE to fully engage the cold air to its N - perfect recipe for a good dumping of snow
  8. Thanks Carinthian. Such situations can be very finely balanced. Quite rare are the classic setups like the one I mentioned the other day from 1978 - hell of a blizzard that was! Too often the warm Atlantic air will push into the cold air and win, not before dumping a load of snow. It's a shame they don't last longer! I'm curious really as to why the GFS keeps producing these kind of scenarios, even though they change run to run. Let's see how the models deal with the run up to Christmas, which is still itself a bit open at this stage.
  9. Ah would that such a chart should verify, some substantial snow would be falling for many. There's that build up of cold air again that I was talking about in my last post, stretching from Canada to Russia. The GFS keeps coming up with similar variations on this theme so definitely something to watch here I think!
  10. I wish I knew the answers! Looking at this time last year, things were very different indeed: Never say never, but I would have expected to see something in place over Canada already if we were in for some sort of re-run. As it is, the pattern over most of continental N America has been strangely benign. That in itself makes me a bit suspicious, because I am wondering how the pattern will change. It just seems most unlike a typical mid-December situation there and I can't get a handle on what exactly will happen - yet I cannot point to any specific "drivers" and say those are my reaso
  11. Having been searching (rather desperately at times I’ll admit!) for some sign, any sign of a breakdown in the relentlessly progressive flow affecting us, no such sign has been forthcoming. The 500mb vortex over the W Atlantic is continuing to spawn LPs in the southern stream, destined for our shores, which has been added to at times by LP in the northern stream which have kept crossing Greenland, preventing any prolonged build-up of cold air, and thus HP there. The GFS has been coming up with some intriguing long-term fantasies, but the short to mid-term has been fairly consistent across t
  12. I was just going to keep quiet for the time being, given the mundane model output in recent runs, but this morning's 06h GFS shows some very interesting changes from previous runs. Not that you can attach too much significance to a single run, especially that far ahead, but it does show potential. The most striking features that caught my eye were the appearance of a high-amplitude ridge over central US/Canada by next weekend, plus the appearance of the Arctic HP. Indeed, on the chart below, there seems to be a noticeable sign of HP attempting to link northwards over and to the W of us. Ther
  13. I was somewhat inclined to keep my mouth shut today after prattling on about northerly blasts yesterday! But I suppose a 24 hour-ish one is better than nothing, enough to make the MetO issue a Cold Alert anyway. However, I will stick my neck out again and say that in spite of the relentlessly mobile pattern portrayed by the GFS, I still believe a more significant northerly flow is possible next week, assuming of course there is enough mid-Atlantic ridging by then, which is sadly lacking right now. The ECM looked most promising: A quasi-stationary polar front straddling the country in
  14. Not to worry John. I should once more describe my own peculiar method, if you can call it that, which relies more on instinct and intuition, after many years of studying charts. My ability to synthesise the many different factors determining future weather trends is largely subconscious, so in that sense not exactly scientific. I just look at the model output and it looks "wrong" to me sometimes. I fully accept your reasoning and logic. It'll be interesting to follow future trends as I find this kind of situation most interesting, with a lot of potential
  15. I've been studying model output on and off all day, and for the life of me I cannot make much sense of anything shown beyond about 3-4 days. The sticking point for me has been the insistence of maintaining progression (except for the GEM earlier, but even that has now backtracked) when, to me, the whole situation right now is shouting "amplification" So, in such cases, I take a look at what is actually going on right now, that is, current analyses and satellite imagery. First, the current surface analysis: So what do we have? A strong PM airstream, LP to the N, a good solid looking HP
  16. Indeed yes it would be! It was the only run that "looked right", according to my unscientific appraisal! If the GEM model is the amplifier, then I guess the GFS is the opposite, so maybe the actual outcome will be somewhere in between. We'll see!
  17. Out of all the latest model runs this evening, I think the only one that seems to have any sort of a handle on future developments past 3 days is the GEM. The GFS has seemed to bring the colder air slowly southwards over successive runs, but both it, and the ECM seem quite clueless as to longer term trends. I would say that as a general rule, once a W-NW cyclonic flow has become established, as it will have within 24 hours, any subsequent frontal development that may occur to the NW, in the Iceland/ S Greenland area, would tend to head SE and reinforce the upper trough that is now developing
  18. Yes indeed! I can recall many winters where HP was close but not close enough to give us the full benefit of the continental flow. Ideally, we need blocking to the N as well, but one step at a time! Later runs might give us a clue as to whether this is a viable option. I shall comment in more detail later if the models warrant it!
  19. My feelings exactly Chiono. I was waiting to see what later runs come up with, but current runs do show the Russian HP a little closer. Once any LP over Scandinavia finally fills, now that is the time when HP can form with a vengeance. I have seen such on a number of occasions in the past. Zonal W to NW flows don't often stay as such for long, usually the cold air will win but occasionally, as hinted by the last GFS, there's a pressure build in our area as the pattern amplifies in mid-Atlantic. Cue the (sometimes quite rapid) emergence of the Scandinavian HP, pushing westwards!
  20. Thank you Mark. I doubt if there is much to support any such development in the current output. I have certainly seen similar happening on past occasions but, as they say, each situation is unique in some way. Anyway, here's hoping!
  21. With the major Atlantic storm in the process of brewing up, it's interesting to see how the models are handling developments following on from that. It is tempting to think that such a major upper trough as will develop with this massive low will cause some sort of knock-on effect in the amplitude of the flow, at least in our part of the hemisphere (I have said as much in previous posts) yet there is currently no such indication in model output. Given the time it took the models to firm up this new storm, I might be forgiven for thinking that future upstream developments might be a bit suspe
  22. I guess it hardly needs saying, but the 06Z GFS portrays a serious snow situation, especially for the N Midlands northwards, perhaps even further south as the 528dm thickness value plunges down across the whole country. The development of short-wave features looks, at this stage, highly plausible, given the proximity of the powerful jet and very strong baroclinic zone. A lot needs to happen first of course but it would be fascinating if such a pattern or something like it, were to happen. Later runs should prove interesting.
  23. What a difference a day makes! The main models are offering up some very tasty possibilities to come next week. It's quite extraordinary how today all the energy that was shown to be following on from the major storm next week, has suddenly faded away. The aforementioned storm now seems consolidated in the model output, so we are left with a variety of solutions as to what follows it. I mentioned yesterday how storms of this size and intensity can significantly alter the upper flow and this would appear to account for the model differences today. So we have several possibilities here:
  24. Interesting changes in model output in recent days, in particular with regard to the predicted development of a major storm system next week. From being a smaller short-wave development, particularly from the GFS, it is now shown as a very intense LP, pushing some very wet and windy weather our way. Although it's not a done deal at this time distance, given the VERY strong temperature gradient over the E of Canada in a few days, it seems quite likely. The other models are gradually coming into line with this projection but developments beyond the middle of next week are pretty varied, and th
  25. Some interesting remarks spotted this morning in the NWS forecast discussion. It's not exactly clear to me what the implications are for the circulation pattern here, but it looks significant: "...AND WHAT IS BECOMING MORE EVIDENT...IS THE LATITUDE FOR THE WAVE TRAIN MIGRATION. TO ME---IT'S DISPLACED SOUTH OF A 'TYPICAL' LATE-AUTUMN LATITUDE---CLOSER TO 40N-42N THAN 47N-48N ALONG 140W LONGITUDE. IF THE ECENS MEAN IS ANY INDICATION OF WHAT CAN BE EXPECTED...ITS 1/12Z DETERMINISTIC RUN AND 250MB JET FORECAST SHOULD BE NOTED FROM THE SOUTH COAST OF JAPAN TO 40N 140W BY THE END OF DA
  • Create New...