summersnow

Model output generally starting to agree on supporting a much less settled and cool/cold pattern for some time to come. Any suggestion of a quick return to HP residing over he UK seems to be fading with each model run. It looks in fact, like a pretty classic spring mix for most, albeit a bit on the chilly side!

Apologies for off topic replies/comments folks! Back on track......remarkable consistency between GFS 00z and 06z runs deep into FI - I don't think I've seen such consistency in consecutive runs since the mighty Azores HP started getting a hold on the output back in December! Still a very marked calming of the Atlantic and ridging into the northwest...and LPs still projeted to track south. A long way to go, but GFS has been onto this one for a while now.

Sorry, I beg to differ! Ultimately water is more important than tourists. Without water there are no tourists and eventually no life! A bit fundamental I know, but things are getting pretty desperate in some areas and current model output breathes a bit of hope for parched areas. The price we pay for living in this green and pleasant land is an unpredictable climate. Most tourists understand this and come anyway!

Depends which way you look at it I guess...it may well bring some much needed precipitation to drought areas. Nice weather is nice, water is essential!

Both GFS and ECM seem pretty keen on the Atlantic dying off a fair bit in the next 10 - 14 days or so and GFS again showing height rises over Greenland in FI. I also notice that the warm SST anomaly coming off the American east coast is at last starting to fade, so this may one factor contributing to a less potent Atlantic ridge, which according some model output, seems to want to migrate further west before eventually ridging into Greenland. All this sets up the distinct possiblity that the overall pattern will stay cool or cold, with air from mainly the north or north east. Again, this is pretty much what the Met Office has been idicating in its current 16-30 day update. If it comes off, I'll be really impressed with the MO performance so far this winter.

Yes, I noticed that almost as soon as I posted my last contribution above...as I say I think this will slowly re-establish itself as the default trend on GFS and other model output for Easter and beyond.

GFS 06z sticking to its guns with a sustained period of cooler weather right up until the end of the run. But it all looks a little suseptible to change. GFS showed last month a similar 10 days+ set up with the Azores HP positioning itself further west & orientating itself with an associated NW to SE flow on the its east side of the ridge. With this SE bound jet, lows had been projected to track further south. Alas, the Azores HP had different ideas and as the event closed in, so the models changed to showing the mighty Azores HP moving closer to the UK and switching orientation, thus returning the weather to the predominant pattern of this winter. Suffice to say that the current 06z set up (Easter & beyond) now looks very similar to that I've described above, while I have also noticed that the exceptionally warm SSTs continue to pump eastwards form the Eastern Seaboard - as they have done all winter! In a nutshell, I don't believe the Azores HP is ready to capitulate just yet, as regards its influence on UK weather. So in the short term, we will definately see a significant cool down but in the longer term, I'm not convinced the cold will last as long as GFS has been fairly keen to model in the majority of its runs over the last few days. While ensembles might tell a similar story, I've observed them to switch as quickly as any of the model runs presented. IMO the warm anomoly off the Eastern Seaboard has continually been one of the major contributing factors in re-inforcing the power and dominance of the mid Atlantic ridge/ Azores HP this winter. While that anomoly remains, alongside relatively warm SSTs to our west and north, I don't see any sustained cold on the horizon but more likely a continued tendancy for the Azores HP to be displaced further north east. Clearly, such a pattern does not bode well for rain for the south east, so I do hope I'm wrong in that respect. It might however, be more likely to cause generally more ridging over the UK in spring with associated pleasant weather, as we have seen for the past few weeks.

Well done to ECM for picking up on this 10 days ago, keeping it pretty much on he cards and now looking certain that we are about to experience a big cool down. Quite how long it lasts is still up for debate but there remains a real possibility that we will see a second shot after 5-7 days. Gfs actually picked up on this more than week ago, when it was still a long way off in FI. But it remained a reasonably constant theme albeit with the normal wobbles as it gradually filtered into the closer time frame. It wil be interesting indeed to see whether or not this verifies but there does seem some fairly strong support now for a fairly sustained cool/colder period, with relatively short lived milder interludes for the next 10 days or more.

I remember through the 1980's, we would almost invaraibly have snow around Easter and often into May - we called it the "lambing snow", as it would arrive during the lambing season - in Highland Scotland. It was almost always also the result of a northerly blast similar to what we are now seeing on the models for the coming event. In those days, it was usually the sting in the tail of winter. The difference this year is that, it will be our winter!! Good model agreement now that we should get a fairly classic looking "lambing snow"....something we have seen in a small minority of Springs in the last decade!

Thanks Gavin! I'm not quite sure what to make of the ensembles this winter - they seem to have chopped and changed as much as runs presented and often u turned in line with the model output! I always believed the ensembles to give a clear idea on how much divergence there is between the various solutions but there have been times this winter when even with quite tightly packed ensembles, it has suddenly changed and scattered the ensembles within 12 hours of output!

Yes, looking like a colder interlude approaching but not as sustained as some recent runs had been projecting. On the GFS 00z, the Azores HP wins through once again - just! Whereas last night's 12Z had the polar air taking control, GFS continues to wobble about in the medium to long term. ECM has consistently projected this colder event but has flirted back and forth with how long it will last. Currently it looks like the recent MO 6 - 15 day update looks pretty close to the mark. I think there may be another couple of swings yet in the models before we can have more confidence in the medium to long term and therefore how long the cold might last!

Fair enough John, I'm sure you're right....however, MO has changed the update from what it was a week ago. The point I'm actually making is that a week ago MO was projecting something similar to what is now appearing on GFS 8 days or so hence. So, the 6-15 day outlook of a week ago may well yet be right and if so, well done yet again to the MO! I suspect also, as you say, that MO expects most likely a mainly westerly airflow with perhaps a little more hint of a n'westerly up north, taking the edge off the temps. But notably they haven't stated this. Whereas last week they were quite confident at first, that there would be mainly a north or northwesterly airstream during the same period, with detail such as wind direction indicated, it was plain to see where they're coming from. All the MO states now, however, is temperatures "nearer average" and "feeling" cold in the north. With all due respect, this is a much more vague statement than giving a source of the air mass as they did last week. Given the MO success so far this winter, the most recent update is likely to be closer to the mark, but I do wonder whether there is a bit of hedge betting going on - especially as earlier in the winter we saw the MO quite openly hedge its bets by giving probability updates in % form...quite right in my view, given that particular situation! Now given the nature of the current 6-8 day output, it actually doesn't surprise me to see the MO target a bit more of the middle ground, as it is often the hybrid solution that verifies. I may well be barking up the wrong tree, but if so, I'm sure you'll take the opportunity to advise me appropriately! But, please don't automatically assume I'm having a go at the MO! As I've stated on several occasions this winter, I think the MO has done very well in its updates and that is why I like to use the MO's take on things in conjunction with what the model output. It is of no surprise therefore, IMO to see the MO give this update, given the nature of the model output trend!

On GFS 12Z, it's T+144 through T+168 where the watershed currently lies. It looks like another classic battle between ridging from the Azores coming up against polar air being generated by height rises over Greenland. A bit knife edge again, but I do stand by my earlier statement, as I do think the energy in the Atlantic is starting to be diverted elsewhere. It wouldn't surprise me at all however, to see the Azores ridge re-establish itself again, at least partially over the UK. Met Office also sitting on the fence a bit with its recent 6-15 day update. "nearer average temps" and "feeling cold in the north", seems like its hedging its bets somewhat and in line with GFS 12z! Last week, however, the MO was fairly consistent with a cooling scenario, so I think this just goes to show how close a call it might be once again at about 6 -8 days out.

GFS 12z continues with the cool down well into FI - even without particularly strong northern blocking! It looks like we may well see a vigorous LP develop in or around the North Sea, bringing a return of winter to the north and more importantly... cool, possibly very wet conditions further south! Still a long way off, so normal caution required. It will be interesting to see what happens this time, as the Azores HP makes yet another attempt to control proceedings in the medium term. My instinct is to suggest it will fail on this occasion (as per GFS 12z), as the Atlantic looks to be calming down, which is to be expected at this time of year. Also GFS hasn't been so bullish about this kind of colder pattern change with troughing over the UK this winter, so I suspect it's onto something. In fact, GFS has been the model to favour defaulting to solutions of Azores HP dominance for months, so it's interesting indeed to see it offering something different through FI and now filtering into into the reliable time frame

As I pointed out above, 2 days ago, the cool down that has been quite consistently showing on GFS in FI, is gradually now filtering into the reliable time frame. Still a great deal of caution needed, but if GFS 06z verifies then we'll be having a late winter in the north and plenty rain for the south!

I must admit, I'm struck at the contrast between ECM and GFS. While ECM continues to show a northerly starting in 4 days for northern areas and lasting some 4 or 5 days, GFS 12z shows a much less potent scenario with it all happening a bit further east. This has been pretty much the theme with this event from the onset - ECM keen, GFS not so keen! But also of interest is how consistently GFS is showing a sustained cool down after about 10 days. It has been showing this scenario in FI for some time now and has been fairly consistent with it. Clearly well into FI, it should be treated with extreme caution but when GFS is as consistent as this in FI, the synoptics do often gradually filter into the reliable time frame before other models start picking up on it. It's often at this stage GFS seems to wobble about a little and then jumps back on board within the even closer time frame! It's quite odd!

Yes, models now showing a northerly airstream as looking likely, at least for a while! I've been pointing out for a while now that the Met Office has consistently stuck to its guns with this outlook and given its track record this winter, I'm inclined to to agree! The Met office always comes in for stick when it gets things wrong but let's give credit where it's due - its been ahead of the game for most of this winter and even gave a winter probability forecast back in December, which has been spot on! Well done the Met Office....this winter!! Also of note is that ECM has downgraded a little at 00z compared to most of its earlier runs, while GFS has moved everything a bit closer to the ECM solution - a fairly typical hybrid, as many of us suggested might happen and will be the most likely outcome IMO.

ECM has been very consistently showing a cold plunge for several runs and the Met Office continues to back this scenario in its longer term outlook. GFS still seems to want to bring it on later. Nothing certain but looking more probable every day. Plenty of time for downgrading and back tracking though!!

Yes, GFS 06z now showing a northerly outbreak as well but at a later stage than ECM. Higher probability now than at any time so far this year of such a scenario verifying within the next 2 weeks or so. GFS still not particularly keen on this though considering its wider output over the past few days. For me, if the Met Office continues to back this trend, I'll remain reasonably confident of it verifying in some form or another!

Not looking beyond 3 days is complete nonsense! I have also noticed the tendancy for some to suggest this but to be honest, generally the model suite does pretty well at determining trends well beyond 3 days. There are times clearly, when the models jump around, and it is during such times that some model output needs to be treated cautiously. But , this certainly does NOT mean that model output beyond 3 days should be disregarded. The fact of the mattter is that some models did intermittently flirt with the idea of a sustained northerly during the winter period but it was never a consistent trend and despite several solutions showing a block to the northwest establishing itself, this never bacame consistent enough on more than one model for more than 60 hrs or so of output. But, crucially, unless you look beyond 3 days, you'll never be able to determine whether or not there is such consistency in model output. In this current northerly scenario, ECM has been fairly consistent now for at least 3 days worth of output, whereas GFS is not keen on anything potent or sustained. Because of this significant divergence between what I regard as the big 2 in the longer time frames, there remains a fair bit of uncertainty. Interestingly though, the Met Office is suggesting in its longer term outllook something similar to the ECM scenario ie airstream predominantly fro north or northwest. You are not being negative, you've actually highligted a valid point in some of the discussions!

ECM 12z dives back into a northerly scenario, which would probably be more sustained than anything so far this year from that direction - should it verify. GFS doesn't quite get there but shows a similar, yet much less potent trend, with the northerly never quite getting to out shores. Indeed the UK seems to protected throughout in a bubble of relative warmth! Met Office still backing something akin to ECM, I note!

"I personally interpret this as a rather watered down northerly break down followed by "business as usual"! Could still mean some rain for the south though, after the coming week of pleasant weather!" GFS 12z now starting to show something akin to the above,,,it will be interesting to see if others models and the Met Office outlook changes to suit.

While ECM 00z now allows the northerly to break down quickly, the Met Office sticks to its guns with the "cooling trend" from 6-10 days and continues on that theme into the 16-30 day outlook!? GFS meanwhile, has jumped from a very cold outlook from next weekend at 00z to a much wetter outllook at 06z. I personally interpret this as a rather watered down northerly break down followed by "business as usual"! Could still mean some rain for the south though, after the coming week of pleasant weather!

Good summary! The Met Office still seems to be backing the idea of he Atlantic block. Due to its pretty good record so far this winter on 6 day + forecasts, I reckon it won't be too far off the mark - although I agree a half way house between current GFS and ECM solutions is quite likely. I would also agree that GFS 12Z is at last showing signs of jumping into bed with ECM!

I must admit, I'm quite interested in the continuing divergence between ECM & GFS. Another fairly distinctive watershed event as regards model performance this year - something that I believe GFS is winning so far, when it comes to 7 days and beyond? I don't have stats to back this up, but my gut feeling is that ECM has been the model to suggest more solutions such as this all year (2012), whereas GFS has been much more keen on Azores HP default dominance. I refer obviously to medium range trends ie a week to 10 days, rather than specific detail for shorter range forecasts, which is where I suspect GFS falls down somewhat. I'm sure there are those who will willingly correct me if this gut feeling is way out...please feel free to do so! I have also maintained since late Feb, that I expect a pretty notable northerly at some stage during Spring, as the equinox, solar activity and sea ice melting all start to impact. Maybe this will be it, although a good couple of weeks later than I had originally expected! I guess, ECM has got to win one of the big battles at some point as well... but then again, maybe it will end up being a hybrid solution as it often does!