stodge

Morning all Still plenty of options on the table in the mid term this morning. The pattern of a slowly sinking Scandinavian HP (option 2 from my contribution from the other day) combined with a strong LP system near Iberia mean the airflow swinging from East to South over the next few days. Unusually for a "breakdown", this isn't happening because of an Atlantic incursion. Rather, it's a combination of the PV displacement to Siberia carrying energy over the far north and suppressing the HP and the failure of the Atlantic to provide a strong counterbalancing southern arm to hold the HP in a halfway house between HLB and MLB which is driving the evolution. Beyond, there is, to pout it mildly, a lot of confusion. Fans of cold will want to see this morning's ECM verify: Plenty of interest in this chart but two obvious points are the moribund Atlantic and the clean lift of the PV out of NE Canada/Greenland toward NW Russia.. Clearly, the opportunity exists for a height rise over Greenland and for the trough to drop into Scandinavia which offers the option of a N or NE flow further south. GEM goes a very different route perhaps more strongly following the hint of an Indian Ocean solution on the MJO. The other thing to note is remnant PV energy hanging back over Greenland preventing a height rise allowing heights to build into Europe from the SW. GFS 00Z OP at the same time. Closer to GEM than ECM it has to be said. Interestingly, the PV is moving more toward Siberia than Scandinavia but there's no sign of a Greenland height rise but a less aggressive ridging into Europe but the net effect is to bring back those SW'ly zephyrs beloved of some. The GEFS for that time offer a huge range of solutions as you might expect and the lack of a clear signal speaks volumes for the current situation. Developments in the stratosphere remain of interest going forward - I confess to my lack of knowledge on this - but I note the 10HPA temperature warming from -76 now to -64 in a fortnight which would suggest a weaker and more disorganised PV from mid month. I think it's odds against a successful "Greenland " option at this point though it's certainly not to be ruled out. With a quiescent Atlantic, the possibility for a new Euro block remain present though more south based than the one we are currently enjoying/enduring (delete as appropriate). Without that, I think we're 3 weeks off our next cold spell once this ends but I'm less certain than I was yesterday. The 06Z OP has rolled out as I've put this together and in FI a lobe of energy is sent back into Greenland but is almost immediately expelled back over Canada - curious. Could this be the immediate response to the next warming phase on the Siberian side or is this a "default" response to a messy PV displacement ? We'll see.

In Woking holding at 1c - extremely chilly though not as bad as a couple of weeks ago. Heard from a couple of colleagues reports of snow in Hampshire from a shower.

Afternoon all Thanks you for the post and the insight, GP. GFS 06Z OP in far FI looks to a renewed round of warming though more from the southern Eurasian side then the Siberian initially. The initial response will presumably be to push the PV back over to the Canadian side - whether far enough to allow blocking to the NE/N fairly quickly or not I don't know. Given the traditional 10-14 day response, I think we're looking at a 21-day period of milder conditions from the end of the current cold spell next Tuesday to the next blocking episode in March. March isn't too late for lowland snow by any means under the right synoptics and indeed one could argue a warmer North Sea in March provides more convective potential. I'd like to argue for the Greenland option but that would require some changes on what looks like the pattern - GFS danced with it yesterday dropping a lobe of the PV into Scandinavia and offering a N or NE'ly airflow over the British Isles. I'd hoped a clean lift of the PV to Siberia would enable the height rises and I'm still not wholly convinced that door is closed but I'm much less hopeful than I was this time yesterday.

Afternoon all From 11c yesterday to just 5c today in lowland East London quite a noticeable change with a light ESE'ly breeze picking up and lifting the cloud a little. Not expecting any settling snow this weekend but might see snow falling, Friday into Saturday looks particularly cold. Far from certain where we go after early next week.

I suppose everyone's interpretation of whether March is a spring or a winter month will vary and the atmosphere doesn't care much! IF we are looking at a second Eurasian warming in mid month or later, that will mean the PV moving back into Canada/Greenland for 10-14 days before we see a tropospheric response. and that means into March before we get another bite at some blocking. IF we get a clean lift of the PV into Siberia (the very thing which is causing the Scandinavian HP to sink) the opportunity for height rises over Greenland exists as I explained in my previous. The problem is, if enough PV energy remains to prevent a Greenland height rise we will be stuck waiting for the next warming. The tropospheric response to the second warming will be another attempt at HLB blocking in Scandinavia in mid March - it would be "better" if the Greenland option played out with the trough dipping into Scandinavia as yesterday's 06Z OP FI showed but that isn't being shown as strongly this morning for reasons I can't fathom at this time. It might be a consequence if the second warming displaces the PV further into Canada - the new warming has a more European than Siberian hint so the possibility for me is the displacement will be further west and we would be back in the game. As ever, more runs are needed...

Morning all After yesterday's angst and anguish, more of a sense of resignation this morning I sense. There's no point arguing the toss - the 00Z Output was poor or very poor for cold and for a continuation of the cold spell past next Monday or Tuesday. As has been suggested, the secondary displacement of the PV from Canada/Greenland back to Scandinavia has taken energy into the northern arm of the jet and caused the HP to sink. This would be fine if the flushing out of the vortex enabled a height rise in Greenland but after some encouraging signs yesterday, GFS in far FI is much less encouraging today and indeed rubs salt in the proverbial by sending the PV back to Greenland - this could be the response to another forecast Eurasian side warming. The PV is weaker and less organised - no question - the 10HPA temperature down to -64 is a good sign - but time is against us and IF the next warming requires a further 10-14 day response as the PV shunts back to the Atlantic side, then we are looking at early March for the tropospheric response which might be another attempt at a Scandinavian HP. The frustrating thing is we are very close to the Greenland HP solution: At this stage you couldn't rule out enough correction to orientate the Greenland ridge further south, send the Atlantic LP a bit NW and try to dig the Scandinavian trough a bit south. Unfortunately, it doesn't happen this time on this output. It will be interesting to see if the Greenland HP has any support in the 06Z GEFS and whether it's an option we'll see on the 12Z.

I don't know what 10/10 means to you though I can guess (as for most on here) it means copious amounts of lying snow. Was that ever on offer ? I don't recall many runs showing widespread heavy lowland snow. I'm a fan of cold - snow less so - so perhaps my perspective is somewhat different but I see plenty to like in the OP charts. We are certainly at a spell of below average and indeed well below average temperatures over the next 10 days - the possibility (and that's all it is for now) of retrogression and a reload from the north is there. London should be at 8-9c by day but I don't see that in the near future. A couple of charts before the Mods get annoyed: This morning's UKMO T+144. That's a solid chart for cold and some wintry possibilities for the SW. IMHO, the UKMO has done extremely well this winter and its consistent support for this colder evolution has been a strong support. Here's your "jam tomorrow" chart: The PV gone - a lobe over Scandinavia and solid heights to the N or NW and a family of channel LPs in a cold NW'ly airflow and it's still February. Excellent.

It really is annoying when people scream "downgrade" because one OP run isn't showing storm force Easterlies and -20 Uppers where they live. Another cold or very cold OP and quite similar to the 00Z output in FI which inspires confidence. The retrogression process is slow but it does allow the trough to drop into Scandinavia and offers a N or NE airflow with LPs passing along the Channel and that set up in late February is as good as it gets for those wanting snow - it's a similar set up which has provided lowland snow in late March. As for the 2m temperatures, oddly enough the 06Z looks colder than the 00Z next week so we may get up to 5c some days (may), there will be some sharp if not severe frosts and no sign of a blowtorch SW'ly.

Morning all More excellent output in the short term this morning. The T+144 output from the suite of 00Z OP runs has a lot of consistency for the British Isles in terms of a SE'ly flow but the orientation and strength (and indeed on GEM the very existence) of the Iberian LP is very different. These charts scream cold and dry to me with a harsh wind chill through the weekend and into early next week: Moving on and as we can't see what UKMO would offer at T+240, let's start with GEM: Anticyclonic and if anything the HP seems to be building back into Scandinavia - no sign of the Atlantic or any milder weather - with luck, sunny cold days and cold very frosty nights. ECM at T+240 and I know a lot of people will be going on about downgrades and all the rest of it: The Northern Hemisphere overview tells a rather different story. The HP has sunk but that has allowed the PV to drain out of Greenland/Canada and across to Siberia and signs of heights building behind that. The progression from there offers plenty of "potential" for a Greenland height rise so not one to be too upset about. GFS at the same time: Superb chart for those liking cold and possibly even more with that trough over us - not so much full on retrogression but a broad block from Greenland to Europe with the Greenland core the more prominent. The 850s aren't fantastic though as always they don't tell the whole story. The far edge of FI has the PV more or less due north of the British Isles and the trough trying to drop over Scandinavia so plenty of cold available there. Just skimming the GEFS at T+240 - as you'd expect a lot of solutions are on the table but hardly a SW'ly zephyr to be seen. The majority cluster keeps us in an E'ly flow of some sport with plenty of HLB but a lot to be resolved as you'd expect. The path into the weekend looks set and the early part of next week looks to continue in the cold and blocked theme. I realise many on here want snow and some of today's charts will be a disappointment - HP too close, 850s all wrong etc.- and I understand that though the longevity and pattern of this cold spell is still evolving and with the three main models at T+240 offering such divergent evolutions there's a long way to go yet.

Morning all I last commented on here last Tuesday or Wednesday and I said then that IF we were still in the game in terms of the hunt for a pattern change by Monday morning, it would be time to get more excited. It's been a roller coaster few days topped off by last evening's ECM 12Z OP which certainly set the feline among the pigeons. This morning, however, and thankfully for most people's sanity, order seems to have been restored and for fans of cold it looks a solid outlook though for fans of snow less so. As Mr 1962-63 has reported, it would be unwise to under-estimate the strength of the cold block advancing west into Scandinavia yet progressive (or should that be over-progressive) modelling can do that. As we saw just two or three weeks ago, the "breakdown" from the last European MLB was pushed back four or five days from initial modelling to reality. I then argued for 14 days of milder Atlantic-dominated weather. I was wrong - well, partially. Some of the blowtorch SW'ly charts presented by GFS failed to materialise as, to be fair, did some of the storm-laden outlooks from some of the other models. It's not been that mild or that stormy (especially in the SE) - there has been rain but not enough to set against what has been an unusually dry winter so far. So, what now ? For fans of cold (as distinct from snow), the ESE'ly set up is as good as it gets. The minimum fetch across the North Sea for frigid air accentuates the cold and is much better for sunny days than the traditional E or NE airflow which picks up cloud from the warmer North Sea. The forward energy in the northern arm remains a problem but as long as the core of HP remains above 50 degrees North, the air flow will remain nice and cold. Blocks don't last forever - the Scandinavian blocks usually go one of three ways - one, they retreat back East into Eurasia, two, they sink South and three, they retrogress West to the North of the British Isles and then to Greenland. The model output is offering the possibility of a Northward ridging Azores HP setting up around Iceland and that would certainly maintain the cold blocked regime. GFS in FI has sniffed at option three on a few occasions and that remains the holy grail for cold/snow fans. Whether we will see enough retrogression to allow the trough to drop through the British Isles and re-enforce the E'ly flow remains to be seen but that would be the ideal scenario for snow fans. I must confess Option 2 would be my favourite at this stage as strat displacement needs to be just right to keep the Atlantic at bay. As for the models, UKMO has, IMHO, led the way this winter and has been solid throughout the approach to this new cold spell. This morning's output suggests Option 2 (see above) but it's very early to be dogmatic about the weekend and beyond. GFS has, with the odd flip and flop, done very well in general terms and this morning's 00Z output was more eye candy for cold and snow fans. ECM hasn't been so supportive of a long cold spell and has played Option 2 strongly in the past 24-36 hours. As with others, I've struggled with elements of the ECM evolution but it cannot and must not be dismissed out of hand. GEM has played a good hand as well - it's a model which never goes overboard with blocking but has been consistent.

It was surely unrealistic to expect the near SSW to "finish off" the vortex - it's only early February. Some recovery was inevitable but the PV will be weakened and the zonal winds much slower - we've had winds running at 80-90 m/s. We may get a short period of reversal before a recover yo what 20-30 m/s at best. More evidence of a weakened PV liable to further displacement.

Indeed and last year's event wasn't an SSW but an early and very dramatic Final Warming into March. Signs the PV will recover slightly from the near SSW going into mid month and I'm interested to hear your view on that being a potential positive for UK cold. I'd always surmised a weakened PV would be vulnerable to further displacement (to Canada) which would aid the tropospheric response in the form of a westward-moving Eurasian HP but it seemed counter-intuitive to the argument a split PV would be helpful. I suppose the possibility with a split PV is one bit stays over Greenland with the other lobe over Siberia.

As means of comparison between 2016 and 2017, the 10 HPA for mid Feb 2016 as forecast by the equivalent 06Z OP run this time last year: Today: Much smaller and warmer than the equivalent last year.

Morning all As the song goes, "what a difference a day makes". After some uninspiring charts yesterday morning, this morning has brought a notable increase in interest from fans of cold with more than one hinting at some kind of pattern change next week. I genuinely thought we would need this week AND next week before we saw a significant move but we see this as early as next Monday from the "gold standard" UKMO: It's hard not to think something might be happening as early as then. Other models are more cautious on the timing - ECM is the fly in the ointment. The first attempt to build the HP west from Russia fails and sinks south and it's the second attempt that is on the T+240 chart: The lack of lower heights over Europe is the big worry here and unless the LP dives SE it's hard to see how this develops favourably. GEM will no doubt have its admirers this morning: Basically, the Eurasian HP pushes the Atlantic back west and causes disruption to the south thus further supporting the HP. It's a dream chart for cold and snow fans. GFS 00Z OP at the same time: GFS is up to its usual trick of taking a lot of energy north compared to the GEM - if that northern energy wasn't there it would be very close to the GEM. As for the GEFS this morning, the vast majority keep higher heights to the East - the differences are over the strength of the Atlantic and whether the core HP block sinks south (like ECM) or stays over Scandinavia (as per the Op). Very early days yet - a definite three steps forward for those looking for cold and a step and a half for those looking for snow but very far from a done deal as we all know. A fascinating 3-5 days of model watching ahead - it does seem the displacement and weakening of the PV is having an effect and the further displacement of that weakened vortex over Canada opens the door for the Siberian/Arctic HP to come westward with the potential advection of some very cold air but to stress once again, nothing is certain, nothing is definite and if experience tells us anything, if there's a way for Britain to miss out on snow, we'll find it. As for cold, I'd be more optimistic of a glancing blow for the SE at the very least from the westward moving cold pool. As ever, more runs are needed, plenty of time for nerves to fray. There will be significant upgrades and downgrades to come.

For a change, time to consider something more immediate and the likelihood of stormy conditions this coming weekend. The GFS 06Z Ensembles at T+126 are a mixed bag - some develop nothing secondary but the majority do develop quite a vigorous little feature crossing southern counties on Saturday. Timing, intensity and track are still to be determined but certainly one to watch. Compared with the Op at the same time: Plenty of rain and wind on offer for the SW in particular.

Fair comment, my friend. The journey to the next pattern change will be fraught I fear. Getting snow to settle for any length of time in the heat island known as London is a real struggle even in mid winter. It's perfectly possible we've had the coldest weather of the winter and we'll drift gently into an uninspiring spring with northern blocking aplenty. I don't know - no one does. The question for the coming weekend is as the first LP recurves NW away from Ireland whether any secondary features will deepen rapidly to the SW and sweep over England on Saturday and Sunday as both ECM and GEM modelled overnight.

What did you expect ? Only GFS goes beyond T+240 and it was obvious last week we were looking at a 10-14 day spell of Atlantic-influenced weather (this is day 2 or 3 as I measure it). The next pattern change is being sniffed it in FI and it will ebb and flow between runs until a clearer picture emerges and that may not be until this time next week. Even then we may get nothing. As to a "proper cold spell", I don't know what you mean. Perfectly possible to get lowland snow until the end of March - to altitude well into April. If you mean days of blizzards, that ship has probably sailed but if you mean 7-10 days of significantly below average temperatures and lowland snow plenty of time for that yet. I realise the recent HP spell didn't do much for you - for others it was quite noteworthy.

Morning all As expected, some eye candy starting to appear at the furthest ranges of FI now. Far from being anything approaching a done deal and we have a potentially stormy and disruptive spell to get through especially over the coming weekend. The emergence of the Eurasian HP as a player reflects a weakened PV but still sitting in the Canada/Greenland area. Slowing or disrupting that train from the Atlantic is now the key. Some models are keen to disrupt south into Europe and that will be welcome if heights can build behind it but we're still at the ifs, buts and maybes stage. I feel the models have gone perhaps half a step back in some regard this morning with a more powerful Atlantic and a less disrupted PV into mid month and it's perfectly possible we'll get nothing out of this and end up on the mild west side rather than the cold east side. UKMO will show nothing for a week and given what's happened this winter we need to see solid consistent output from the UKMO before we get too excited. Experience tells us caution is the watch word here - this time next week may be the time to start getting interested.

Indeed but it's not an implausible evolution and it may be a weakened PV can be displaced more easily in mid-February. I've seen elsewhere an argument it might finish up over Scandinavia - the Ensembles on the 06Z are solid to T+240 so it's going to be a question of watching storm tracks and rainfall and wind numbers and again the secondary features could be the real problems. Into far FI and some other options are on the table as you'd expect. In the more immediate, quite a severe feature for Ireland and the SW in terms of rain and wind - the battleground is obvious here with the block over the Ukraine ridging toward Scandinavia meaning the Atlantic LP isn't moving up to Scandinavia but recurving back NW into the Atlantic. The story of FI is the gradual transition from a West-East battleground to a more traditional North-South one.

Morning all After yesterday's remarkable ice day in the SE, a significant change is imminent with a return to Atlantic-dominated weather. Too early to get an exact feel for storm tracks and intensities but the general view from the models is of a succession of vigorous depressions moving SW - NE up the west of the British Isles with copious amounts of rain and wind especially the further west you are. The secondary features could be the real problem as one or two of them deepen explosively in the flow. The Jet is strong and over or just to the south of the British Isles so all areas will see some wind and rain and the latter won't be wholly unwelcome after an extraordinarily dry winter. We're in this for at least 14 days in my view - I do think the upcoming warming and further activity will weaken the stratospheric vortex - the 10HPA temperature rises from below -80c now to -60c in a fortnight so that for me is an indication of a weakened PV which may be vulnerable to further and more advantageous displacement. The GEFS members are starting to sniff some options at the furthest edge of FI with both Greenland and Scandinavian blocking options from one or more of the members though it has to be said the majority keep the Atlantic flow. Going beyond mid-February I still see plenty of opportunity but as always we need a fair bit of luck and the cards to fall right. The models aren't going to make pretty viewing (unless you like stormy conditions) for the next week or so - by then, I think we will start seeing some eye candy in FI and the chase can begin in. After 10 days of cold, I won't mind some warmer weather.

Morning all A remarkable day yesterday - I've lived in East London for 13 years and this was only the fourth ice day I've recorded in that time. Indeed, as others have reported, the temperature actually fell slightly during the day as the chill wind intensified. It's the first ice day since March 11th 2013. This spell of cold weather which started on January 16th has been interesting. I know for those who only want snow it's been frustrating but for fans of cold it's been noteworthy. Five consecutive days of unbroken sunshine from Tuesday to Saturday is remarkable and a long series of consecutive night frosts (and harsh frosts even for London and with another sharp frost overnight). As is so often the case, these anticyclonic cold spells have left the best for last as the entrenched cold is intensified by a SE'ly flow from a frigid continent as the Atlantic approaches. We've had two or three spells of fog - last Sunday night's freezing fog was as thick and persistent as I have ever seen. Had we had a cover of snow, yesterday would have been even colder - possibly approaching 18th December 2010 but a long way from the remarkable January 12th 1987. I wouldn't be surprised to see some March snow in London - it's happened plenty of times in the past.

Afternoon all Well, I have to confess I'm looking forward to my lunch of humble pie with oeuf sur visage to follow. The block has proved more resilient than I thought earlier in the week (and the models indicated). A final chilly hurrah but the current models seem to indicate the Atlantic coming through over the weekend and then, as I expected, settling in for a 10-14 day spell. Straws in the wind - the last few days of model watching have seen big changes from day to day so this may not be a done deal quite yet and the long fetch SW'lies promised especially on GFS earlier in the week have been replaced by a more perturbed outlook as the jet oscillates further south next week. There are colder members in the GEFS but not too many in FI. There's been talk about the lack of an SSW - the 10 HPA temperatures in FI are down around -68c. Last year they were still -84c or below going into February. The PV will be much weaker and IF there is a second assault in February, so much the better. We shouldn't be surprised if the first result of an Eurasian warming is to displace the PV to the Canadian side - this is what happens. Oddly enough, we may see February, usually a colder and drier month turning out more unsettled and stormy than January which is traditionally the more disturbed month. Still plenty of February and early March to come for cold/snow fans so no need to feel too disheartened at this stage and as others have said, some rain may well be welcome.

Morning all After a fair degree of model concensus, that breaks down spectacularly with UKMO, GFS and ECM all going their own ways in the reasonably short term. UKMO never allows the Atlantic in to the south keeping the jet well to the north and building a new ridge from the Azores HP at T+144. ECM oscillates the jet further south and suppresses the Azores HP completely keeping us in a cooler Atlantic airflow from the west. GFS has been consistent in modelling a spell of long fetch SW'lies through next weekend (could be 12-14c further south next Sunday) before a group of vigorous LP provide a stormier start to Feb. Plenty of colder options in far FI on the Ensembles as the weakened PV staggers round like a drunk on a Saturday night but blocking here, there and everywhere in truth though a significant cluster keeps the Atlantic in charge even to the end of FI. Both ECM and UKMO hold the far SE under "the continental solution" until Friday and you'd back that over the more progressive GFS but plenty to look at and consider in the early output and let's see where the week takes us.

Morning all Not much really to add - the Atlantic breaks through to most of the British Isles by Thursday though there may be a brief continental interlude once again for the SE for 24-48 hours before by this time next week we're all in a SW'ly Atlantic flow. It's hard to argue with the man on top of Reigate Hill - I got slated for suggesting a 14 day zonal spell a few days ago but here we are. Some GEFS members sniffing the early signs of a pattern change but very early days. It's perfectly possible to get settling lowland snow late February and early March if the synoptics are right. The stratosphere has to play ball though and there were no guarantees.

Morning all I'd forgotten how sub-tropical Reigate Hill was - in my part of East London, we've managed 5c a couple of days, 4c one day and crawled up to 7c briefly yesterday. As to the models this morning, well,yes. The spell of long fetch SW'lies looks to be fairly short as the jet eases south and we get plenty of weather coming in off the Atlantic. I don't see an undercut but a strong possibility of secondary features developing and deepening rapidly in the flow so something to be aware of in what has been a quiet winter thus year in terms of storms. Not only that but they offer the possibility of a transient NW'ly which offers snow to altitude. To offer some "hope", quite a lot of the GEFS members in far FI sniffing at height rises to the N or NE - very early days but a clear trend there worth keeping an eye on. IF the Atlantic train can be slowed as the PV weakens from the warming, there is a "chance" for heights in our vicinity.