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stodge

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About stodge

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  1. Yes but the longer the ridge persists over Scandinavia the more the energy off the Atlantic will be drawn SE through the British Isles into Europe which keeps us in colder PM air and offers some snow possibilities for Scotland as LP swing SE through central Britain and into the Low Countries.
  2. You or the Bearded One noted the negative tilt on the trough this morning and it's still there this evening on the 12Z at T+216. There's enough residual heights in northern Scandinavia to send the LP SE into Europe. Similar to the GFS OP at the same time: http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=216&mode=0&carte=1
  3. Morning all Plenty of deflated individuals this morning but to try to be analytical it's worth looking at a single run and a single timeframe to see how the modelling has developed. On Tuesday 4th, the GFS 00Z OP at T+174 A strong ridge moving north and NE across the British Isles with a large Atlantic LP retreating westwards. Wednesday December 5th, GFS00Z OP at T+150: The ridge is weaker, the LP over Eastern Europe deeper and the Atlantic model is different. Now, this morning and the 00Z at T+126: If this cold spell next week has failed, it's because the original ridging from the south has ended up weaker than originally modelled which makes the block over Scandinavia weaker and less able to withstand a vigorous Atlantic but I'd also note the modelling of the LP over the Baltic which is deeper again this morning and also inhibits the development of a suitably robust block. The Atlantic LP was at the start moving west to the south of Greenland but the new LP coming up from the SW invigorates the energy and aids the LP in punching through the weaker block.
  4. Afternoon all I think what strikes me about the 06Z OP, Parallel and Control is how they are all very differently modelling the NH profile in FI. OP tries to restore the PV in its usual place but both Parallel and Control displace the PV away from the Canadian side. As we know, a displaced vortex isn't a guarantee of cold but it's a good start. I don't think anyone thought the colder outbreak was going to last a length of time and to be fair cold spells lasting more than 7-10 days are unusual. Looking at the GEFS I'm struck again by the weakness of the PV in mid December - again, as you might expect from the synoptic evolution, the Parallel makes much more of a second assault on the PV in far FI - the OP is quite muted.
  5. First, thank you very much for the detailed forecast, Ian. It sounds like a typical back-loaded British winter - those wanting snow and cold at Christmas are going to be disappointed but those wanting snow and cold for late February may be in luck. I suspect it's going to be a long and slow pull into spring next year. The indications of early pressure on the PV perhaps offer more hope for a chillier January but as I've mentioned here before, my birthday is exactly midwinter, January 15th, and the number of occasions it's been cold and snowy have been few while more have been dry and cold but the majority have been mild.
  6. I think our first "hope" (and the 12Z Parallel at the very end of FI suggests this) is to get the trough negatively tilted and send the LP SE into Europe. That will need either the Arctic HP to build SW or the Eurasian HP to build WNW and it's the latter which occurs at the very end of 12Z Para FI.
  7. It is modelled a notch stronger on the 12Z than it was on the 00Z - it is now 1030MB for example. As a result, the jet is further north and the LP is tracking further north as well.
  8. Afternoon all Having stepped away from the models for a couple of days, a shade disappointing to see the earlier promise of a blocked situation in early December not quite happening. As I suspected, we are looking at a 7-10 day period minimum of Atlantic-influenced weather and that now looks to be 14 days as it's around T+288 on the GFS 06Z suite we see the next attempt at amplification. In truth, it's not wholly successful as the jet remains too powerful and the block in most instances gets blasted away but there are members where that doesn't happen and the Bearded One's call from the ECM ensembles looks about right at this time. I thought the signal for blocking a little stronger earlier in the week - I do wonder if the pressure on the PV from the Eurasian side is causing the classic response of a re-location to the Canadian/Greenland side so you can add a further 7-10 days while that happens.
  9. The 12Z Parallel hasn't finished rolling out so let's reserve judgement on that. The difference between OP and Control is simply the rifdge coming SE from Greenland is able to hold back the Atlantic LP and indeed push them back westward allowing the much colder air to come in from the east. Oddly enough, the NH profile for the OP gets more interesting at the very end of FI with the PV displaced over the Pole so it may just be a matter of timing.
  10. I suspect while most on here will be hoping for high-level blocking over Scandinavia I suspect we may finish up with the HP right over the British Isles so cold, frosty and foggy conditions under a mid-winter inversion but no snow.
  11. As did I and I think the question about the mid-latitude block is whether it will end up right over the British isles or perhaps just to the west which wouldn't be ideal for cold weather fans. By mid December inversion will be a powerful weapon for those wanting fog or frost and ice days are entirely possible.
  12. Rather depends on position and orientation of course. An intense HP centred just to the south of the UK can be quite clear and leave southern areas cold, frosty and foggy. Ideally, you want the mid latitude block to the east so cold SE'ly air is drawn in from a frigid continent but that tends often to be a cloudy airstream. An HP directly over the UK centred over central or northern England, while technically mid latitude, can often produce a cleaner solution but you do get areas of cloud trapped which circulate so you might get frost one night but not the next. The other aspect of my comment is that very cold scenarios can result from the HP over Iberia transferring NE into Scandinavia That is one of the three ways you get a Scandinavian HP - the other two are a) the Eurasian HP building west or WNW or b) the Arctic HP building south or South-South-West. The latter is extraordinarily rare, the former less so and you can have an intense HP (say 1050MB or higher) controlling our weather but centred over Finland and building a strong ridge westward. The famous 1962-63 winter cold spell started from the Iberian HP moving NE. If you look at the Archive charts on Meteociel, you can see how from 20-22 December, the Iberian HP moved NE over the British Isles and phased with an HP to the east to create an intense block which was centred to the east of Denmark on Christmas Eve and immediately retrogressed as a strong Arctic storm containing a portion of the PV moved ESE near the Pole. By the 27th, the HP was over Greenland and a frigid NE'ly was impacting on the British Isles and the rest is history. It's also worth noting where the core PV was at that time.
  13. Morning all Without wanting to sugar coat it too much we are looking at 7-10 days of Atlantic-dominated weather from the middle of next week. We shouldn't be surprised or assume it's the end of winter or anything like that, We often get a milder spell at the beginning of December so this is just normal pattern shifting and changing. As to what happens before, we'll start seeing some tantalising offerings in the very far reaches of GFS FI before long - my money (and very nice money it is too) is on a pressure rise from the south and mid latitude blocking in the vicinity of the British Isles so not brilliant for fans of snow but fans of cold and especially frost and fog might get a decent spell under a classic winter inversion. The PV profile is very different to some more recent winters and that has to be of interest though my concern as always with those who want everything to happen in Greenland is the risk of the west based negative NAO which killed the 2010-11 winter at New Year. For now, the Atlantic will do its thing until it stops doing it and then we can see if we can get anything out of the next amplification.
  14. Morning all Both GFS OP and UKMO suggest we may squeeze another 24-48 hours of chilly weather out of this spell but it's hard to see how it is extended much beyond this time next week. The problem is the ridging from the south pushing the LP to the NE seems stronger than the ridging from the north pushing the LP to the SE. GFS OP puts the LP over us or through southern Britain and UKMO might do the same but there's nothing for me showing a clear slide SE into Europe keeping the UK on the cold side of the fence. Looking at GFS OP, Parallel and Control all bring some form of PV into its usual place above NE Canada though interestingly at the very end of FI both Parallel and Control suggest any Atlantic-driven quasi-zonal flow could be short lived. We often see a milder Atlantic flow at the end of November and into December and with that you can see some very high temperatures under Foehn conditions in N Wales and the Moray Firth. I'm not seeing that this time. Parallel suggests HP building from the south will eventually displace the jet north and allow HP to set up close to or over the British Isles - a good old fashioned winter inversion, anyone? Control sends the PV energy back west over Canada which could allow for new height rises over Greenland into December which would interest many on here but I think that's a longer shot though the idea of a "cold" anticyclone dropping SE over the British Isles has a lot going for it if snow doesn't float your boat. We will have to endure 7-10 days of milder Atlantic-driven weather before the next opportunity for amplification comes along.
  15. Oddly enough, I think it's a very good run. Yes, there are no screaming NE'lies with -20 uppers heading toward us but the one thing the GFS 06Z OP isn't is raging zonality. It's unsettled and often cold condition to the north of the British isles and plenty of rain for all parts (which is badly needed). Looking at the NH profile, the attempt to build the PV back over Greenland fails and the PV ends up right over the Pole which you don't see every day of the week. It's a plausible scenario going into December and the possibility of heights rebuilding is clearly there. Control and Parallel will no doubt look very different.
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