Uncertainty

The extended clusters show that just because AAM is going down doesn’t necessarily mean summer is done. Some optimism from the ec 46 also for after this period. I’m a big fan of the predictive utility of the GDSM but if it was as easy as rising AAM = good weather / falling AAM = bad weather then forecasting the U.K. would be easier than it is. (I realise no one is suggesting that is the case). Indeed, rising AAM to high levels in early July did little to shake out the U.K. trough. The point is we could eek a settled spell in August despite falling AAM. It’s just less likely than were the inverse true. At day 10, the ec op was in a minority cluster, but 22% is not negligible and cluster 1 wouldn’t be terrible in the Se either. It’s also notable that for this period and the extended the ‘red’ border - broadly indicating scandi blocking - is forecast to be prevalent. This compares to the last 5 weeks where blue (+nao), green (-nao) and purple (Atlantic ridging) were dominant. Usually, and in the broadest sense, the red border is often favourable for summery U.K. weather - especially if the block is close enough to exert its influence over the U.K. In the meantime and after our brief U.K. wide flirt with summer, a potentially very wet pattern is in store for the north west - the GEM showing just about as ‘classic’ a nw/se pattern as you could see. For the SE, should the block in the extended period position favourably (and of course it’s a very big if), then a pleasant period could be on the horizon. The MO seem to support this in their outlook and the noaa charts also indicate reasonable weather in the SE - although it’s a bit marginal to get too excited about. I’ve seen a lot worse than the latest EPS mean for the 19th. So, based on modelling alone, 3 main options for mid / late August, in order of likelihood: 1) remaining wet in the NW and drier in the SE 2) hp builds across the U.K. from NW or SE 3) we revert back to the U.K. trough Given the fall in momentum, the continuing impact of the EQBO and the high solar activity at present, I would probably swap options two and three around.

Both the gfs and icon show an unlikely pathway to a ridge in the east early in week 2. The GEM however is horrid, a stretched out moist south westerly stuck between highs to the far NW and SE - a very wet pattern indeed especially for w areas. ECM was similar this morning and the UKMO looks to be headed that way. You can see on all 3 charts above the influence of the Greenland high, forcing the low to the west to spin nonchalantly and aimlessly. The only question is can we, for want of a better word, ‘fluke’ a ridge to the east ala the gfs. I doubt it. We know the low to the west is going to be there, it’s just a case of can it be held back enough to at least keep eastern areas dry after their fairly dreadful summer so far. whilst there’s hope…

Can we trust it though given the consistent underplaying of the GH? If both occur we could end up with this kind of pattern, which we haven’t actually seen for a long time: a real nw/se split?

Did the last few winters not, for us at least, act in a reasonably canonical Nina fashion? E.g colder and blocked in nov / Dec with wet mild febs? The winter before was led by the super iod and the models saw that. The one before that was dominated by a reverse tripole in the Atlantic and before that they missed the BFTE. Not a terrible track record for recent years. There are plenty of variables the seasonals don’t see very well: Solar, Hunga Tonga etc But if Glosea goes all in too (2009 style) and none of it manifests, then perhaps my faith in winter seasonals will diminish completely. What might happen is the general hemispheric pattern verifies but the GH is generally west based and we get mild, wet and windy anyway.

So we can’t post long range charts because they’ll never happen and we can’t post charts for one model from 5 days away because apparently that’s bad for newbies and they’ll probably never happen anyway? The vast majority of readers know the pitfalls but dammit I want to see navgem 180’s showing dubiously massive U.K. highs in summer and dodgy seasonal models showing stonking Greenland highs for January 6 months out and I want them posted as gospel! We’re supposed to be having fun as well as learning! On that note always good to have you back Frosty!

Is it too early to get excited? Yes I know… no euro low heights, we’ve been here before, it’s just one run, it’s August BUT IM STILL GONNA POST IT

Plenty of evidence to support your assertions Dan however the clusters suggest otherwise… Doesn’t look like a ‘July’ style set. 1, 3 and 4 suggest more than just a flash in the pan - though said flash in said pan could manifest in thunderstorms in such a synoptic. Yes the mjo is weakish but it does appear to be heading to straddle 8 and 1, the former yielding an El Niño composite that doesn’t look out of place with the above clusters. On the other hand, the NAEFS supports your analysis, with blocking too far north to benefit us summer wise. The ec 46 has also abandoned its promise of a settled middle/end of August. Too add to your concerns vis Autumn the high solar activity and developing Nino will also need to be factored in, Cumbrians like myself will be anxious to have the season done. Even the shape and intensity of next week’s ridge is causing huge difficulties in the modelling. It seems frivolous to attempt to decipher beyond that. But I won’t give up and i’m glad you and others on here continue to look beyond the reliable as well. Original post: https://community.netweather.tv/topic/99056-model-output-discussion-mid-summer-onwards/?do=findComment&comment=4900032

Plenty of evidence to support your assertions Dan however the clusters suggest otherwise… Doesn’t look like a ‘July’ style set. 1, 3 and 4 suggest more than just a flash in the pan - though said flash in said pan could manifest in thunderstorms in such a synoptic. Yes the mjo is weakish but it does appear to be heading to straddle 8 and 1, the former yielding an El Niño composite that doesn’t look out of place with the above clusters. On the other hand, the NAEFS supports your analysis, with blocking too far north to benefit us summer wise. The ec 46 has also abandoned its promise of a settled middle/end of August. Too add to your concerns vis Autumn the high solar activity and developing Nino will also need to be factored in, Cumbrians like myself will be anxious to have the season done. Even the shape and intensity of next week’s ridge is causing huge difficulties in the modelling. It seems frivolous to attempt to decipher beyond that. But I won’t give up and i’m glad you and others on here continue to look beyond the reliable as well.

Interesting change in the gem ensembles 12z 0z More emphasis on the high to the SE and less over Greenland. A mean southerly feed for us rather than a S/W. Quite a bit of confidence that (a most likely transient) ridge will build from the 9th and head east. After that we’re back to looking at trends, one option could be a thundery low moves in and is replaced by another transient ridge. Still another week or so of these unusual Atlantic features to come though. Need to keep an eye on Saturday’s, gem has worst winds grazing the south whilst Arpege has it causing some real trouble in western Ireland. Before the sw gets slammed right in the middle of the day on Saturday. Amber if this materialises? There could be yet another feature to contend with on Monday/Tuesday but it remains to be seen if this one develops or if we just see a wave feature. Given our recent history I think the former outcome is to be favoured. Bring on the change I say! It can’t come soon enough!

Hot or warm and wet rather than cold and wet looks to be the long term path. The 18z gfs op and a few ensembles do show that there is a way to get settled weather to stick but sadly it involves multiple ridges to replace each other every few days which seems unlikely with all that blocking to the north which, according to cansips, is going to be with us for the next 8 months! Lol

It’s all starting to go a bit bonkers on the models. In particular, an incredibly rare feature is now favoured to rotate around Scandi around a week away. Look at the sbcape on the gfs! Severe thunderstorms and likely some pretty mental wind speed values. This storm and the ever growing blocking surrounding it, especially (sigh) over Greenland again, is making me feel nervous vis our little Azores ridge nosing in. The Gem manages it and chucks in a heat spike to go with it. The gfs just about squeezes a ridge in to the south but no room for a scandi block with that monster low hanging around! It’s even going to swirl SW and merge with the Atlantic low on this run. A hideous outcome for settled weather for us were it to play out precisely like this. The UKMO and icon don’t look great for settled weather towards the end of their runs either. The latter even magics up ANOTHER bizarre wannabe hurricane at 168 for S U.K.! What the f is that! To me it’s starting to feel ominous and dodgy and usually, when nice things are forecast, whatever the season, once I get this feeling it’s goodbye nice things and hello heavy rain. Seems to happen more when there’s high solar and extreme SSTs eg at the moment. It feels like to get a settled warm period we’d need to get lucky ala the gem tonight. Glad to be wrong. Don’t moan often. When I do it try to make it count Finally, depressingly, predictably, Saturday’s formerly known as tropical feature packed full with high PWAT values and lovely juicy tropical moisture ( like rubicon only a bit bigger) looks now to be visiting the U.K. in classic direct hit fashion rather than harmlessly drifting south. You can clearly see it on the GEFS and on every other model tonight.) Expect the ecm to sheepishly correct itself later tonight. Silly computer models.

@Man With Beard Here’s the 1020mb mean high you were asking for A build of pressure around day 8-10 is now looking the form horse, but of course there are complications because… of course there are. The GEM delays the pressure rise with yet another U.K. bound shortwave The ECM looks pretty, and pressure rises, but our high is flanked by silly amounts of northern blocking, some of which looks like it might ‘suck’ our high up towards the Arctic leaving LP to gill the vacuum. It doesn’t look a stable U.K. high on this run at least. Plenty of gem/GEFS ensembles do this and with all the SST shenanigans it’s a very plausible outcome. Plenty to get excited about, but plenty of ways it can go horribly wrong!

Indeed the ecm still follows its own path - at least it’s not as bad as last night’s run! It also seems to have a significant ridge building in form the west at the end. Jma gets there too Still way too far out to pop the corks, but this gem ensemble is the best I’ve seen since June… There is no doubt the models are latching onto a signal. Time will tell as to its veracity.

Doesn’t look that way tonight pal, I’d be less surprised if it deepened further and thus took a more northerly track through central areas. If agreement there on Monday morning the warnings will start coming out. If it wriggles away from the developmental part of the jet then it wouldn’t develop as much and would go south, but seems the less likely option tonight. I don’t like el ninos personally, especially with this Atlantic SST profile, you just end up with a seemingly relentless spawning of Atlantic lows right at us. Reminds me of august 19 - Feb 20 where they just kept coming week after week. Hopefully we get a breather mid/late August.

Gem having a pop at summer now, no doubt the models are toying with the idea… The GFS has a euro high too but sadly also a Greenland one, so guess what gets sandwiched in the middle? UKMO doesn’t got that far but what it does show is that the tropical feature I discussed this morning might not cross the U.K. as easily or as directly as looked the case this morning. The low passing harmlessly to the south of France on this run. The GFS control still exemplifies the direct hit option What does now seem likely is a deep low passing either through or just south of the U.K. on Wednesday. A fascinating, unusual outlook. Not my cup of tea, but remarkable nonetheless.

This is the tropical feature we may well have to contend with late next Sunday / Monday. Could be ex Emily by that point. Needs watching.

Lots of negativity kicking about throughout the wx community it seems. I get it and there does seem to be a bit of a sinking feeling vis the rest of this autumn (did I mean august?!) but for what it’s worth, the eps have picked out a potentially warmer more summery pattern after the (actually very well forecast) stormy low day 9-11. Need to see it for a good few more runs first, but the models seem to have done really well with the tropical feature that rides the strong na jet so maybe just maybe they can be trusted to pick out a more settled interlude to follow.

The extended eps really have flipped tonight, even at relatively short range. Here’s week 2 from yesterday Now today’s effort Hard to believe it’s the same timeframe! There’s confusion about the set up to the west of the U.K. seen here on the spreads. It could easily flip back to a trough to the w tomorrow. Then again, maybe it won’t. That’s why it’s fun/hard/annoying! Something’s definitely afoof though… *meant to put afoot but actually prefer afoof!

EPS is trending more settled mushy, especially beyond the above time frame. In the 8-14, the chance of hp setting up just to the W in the above timeframe seems to be increasing, even though the trough could still be influential to the east of us. Most gfs ops for the past two days have gone with various variants of a U.K. high in the extended. If the trend continues tomorrow am, perhaps we might see a shift in the anomalies tomorrow night. Although it’s the strongest signal I’ve seen since June, I’ll believe it when I see it!

Finally, low heights over Greenland! Hopefully it has a decent ish cluster to go with it.

The option has been there in the eps for a few runs now. It has little support in its own suite, a few in the geps. Even if that chart does come to pass there’s still at least 12 days of guff to come. It does seem logical if the pacific plays ball. Hopefully it keeps cropping up in the coming runs. I do think settled weather, particularly for the S, will become more prevalent as august goes on.

EPS mean at 300 looking borderline promising Geps at around same time looks reasonable. Just a few early signs August could herald a change in fortunes…

Thanks mate. I know you’re new to the forum but you are keeping things going nicely with your thoughts on modelling and background drivers. Keep it up and get stuck in over winter things could get busy…

Yay! We are seeing a signal for a flip in the pattern in the ec 46, just a shame that it doesn’t start for nearly a month. It’s been there for a few days now, ties in with quite a lot of people’s thoughts and logical reasoning around a recovery in AAM. Also most of the seasonals had an alright august (nothing like as convincingly nice as last year mind). It might be a way off but I think it’s reasonable to look for a pattern change when one is suggested by the background signals. In the here and now, This U.K. trough pattern doesn’t look like shifting in the 15 day range at all. After that it looks a little less clear, maybe a perhaps painfully slow transition to something less miserable. Thats the back end of the GEFS though, no sign at all of the AH moving towards us. It’s looked like that for weeks now then turned more unsettled towards verification. I’m also struck by the lack of U.K. highs in the ensembles. There’s barely a ridge. Grim. We’ve been spoilt in the last 3 Augusts with high pressure, especially in the north. Many before that were utter garbage. So fingers crossed the long awaited AAM surge the cfs and eps were so confident about materialises. If not, then the best of this summer’s weather may already be behind us. The only saving grace is the lack of Nino forcing just might slow down the intensity of the +enso state later in autumn. Here in Cumbria, we don’t want another 2015. If it can stay moderate and head modoki, then… I’ll leave that for another day

Careful what you wish for NWS!