nick sussex

Unfortunately the limpet high over Greenland shows no signs of weakening significantly to allow the jet to track much further north, there is a brief window of opportunity around the 144/168 hrs timeframe when the Azores high ridges ne but even this can't be relied on just yet as the models in recent weeks have tried to take the jet further north in later outputs only to take this further south towards the reliable timeframe. In terms of FI if you believe in miracles perhaps we might see a more western based negative NAO develop which can steer low pressure on a more ne track, if that does occur then you might see a more nw/se split in conditions but save for that its looking dismal. If the Azores high does manage to deliver a mini drier blip the flow looks quite humid from the sw so in terms of any sunshine this is more likely further east. The problem at the moment isn't just those positive anomalies over Greenland but the placement of troughing which after the possible two day drought! looks once again to be centred UK through to Scandi.

Both the GFS and UKMO at 144hrs agree on some shift ne of the Azores high, however those positive heights over Greenland remain. Given the low expectations a change to a more typically unsettled pattern with at least some occasional ridging ne of the Azores high would at least give the odd drier day. We'll have to see what trend develops now regarding how far northeast the Azores high ridges, it might turn out that southern and central areas of the UK do best with the most unsettled conditions being in northern areas. Looking at the GEFS maps for 168hrs, good support for the Azores high edging ne'wards but although heights over Greenland drop a little the jet is still further south than should be expected at this time of the year.

Thanks, to be honest given your rubbish summer so far I'm not complaining down here,rainfall has been around average, we've had quite alot of dry weather and the odd very hot day, not as much sun as normal but its generally been okay. You're right to be cautious though given that the models have tried to remove those heights over Greenland in their later outputs before and this has imploded as the output gets into the more reliable timeframe. I'm slightly more optimistic this time as changes start around the 144hrs mark especially on the ECM output, the jet doesn't look as amplified and the Azores high is edging more into its normal summer position.

At last some better news from the models especially the ECM which finally starts to ridge the Azores high further ne and lowers those positive heights over Greenland. The GFS doesn't look as good and the UKMO hard to say as that only goes to 144hrs, much depends on the track of the low at 144hrs which leaves the eastern seaboard of the USA, a ne track will signify at least some change in the jet with less southwards pressure being exerted from those heights over Greenland. What is agreed on though is the more characteristic summer orientation of the Azores high at 144hrs, once you get that orientated ne/sw and closer then its much easier to at least get some drier interludes. We'll have to see what the trend is over the next few runs, what has been evident is that the models have tended to edge the pattern further south from their later outputs as they overplayed the weakening of high pressure over Greenland at that time range. So thats still a concern , but certainly from the ECM thats the best output within 168hrs we've seen for many weeks.

The ECM output is an absolute horror show for decent summer weather with those Greenland heights forcing low pressure into the UK, the GFS is positively wonderful compared to it in its higher resolution as that at least brings a weakish ridge in . The problem when you get stuck in this negative NAO rut is how quickly this ends, unfortunately the omens aren't good as these patterns once set are very hard to break down, in winter we do often see this becoming more west based at times and really this is looking like the last hope to salvage something for the UK this summer, if the core of those heights can transfer far enough west we might see troughing developing further west and north forcing some ridging ne towards the UK, though you need the right alignment to pull up that warmer southerly influenced flow, at least you manage some drier much warmer interludes. For longer term summery weather of course the best option is the Azores high ridging ne and staying but that shows absolutely no sign of doing so at the moment.

So you're going for the shift being troughing edging west and a western based negative NAO to put the UK on the warm side of that with a flow sourced from the south, at least that doesn't require a major change of pattern but some westwards adjustment. I'm sure most people could cope with the odd deluge if its interspersed with some sunshine and warm temperatures, realistically if those heights remain near Greenland thats the last hope. The Azores high looks firmly entrenched in its current location, i'm sure it will be back though once the summer finishes!

I think dismal would sum up the current modelling, any decent FI output implodes nearer the time with the models prematurely trying to lessen heights over Greenland, the ECM in particular has been all over the place. Now the UK looks set to be plagued by the limpet low for much of the coming week, as this fills at least there maybe some sunshine and with lighter winds it won't feel too bad from Wednesday onwards however there is likely to be some heavy and thundery showers which could produce some large rainfall totals. Absolutely no sign of anything in terms of a decent spell of summer weather, you can get decent conditions if the negative NAO becomes more western based with trough to the west of the UK but at the moment troughing remains stuck over the UK. I certainly would ignore any suggestions of the Azores high ridging ne towards the UK unless this lasts into the 144hrs timeframe on the models.

Thanks yes most people associate me with my winter postings but I do occasionally appear in the summer if theres something noteworthy or when i start obsessing over the conditions for Wimbledon! It does at least look okay for the start of the tennis, there is quite alot of uncertainty though later in terms of the track and location of low pressure and how much influence the UK will see from any ridging over mainland Europe.

Thanks, I normally surface at this time as Wimbledon approaches! Regarding the outlook and following on from TWS post, there is some uncertainty as to whether we're going to see these lows further north which would at least allow a warmer type of showery regime, we are reliant though on the negative NAO relaxing slightly and becoming further west based. The ECM output does suggest that but thats really been all over the place in FI, given the current NH pattern the best the UK can hope for is to get on the warmer side of low pressure and if this can stay far enough to the west then we could see this allow some ridging to edge north out of France and bring some warmer conditions up from the south, the best conditions in terms of warmth and something akin to summer between the showers looks more likely for eastern and se areas. The problem that has plagued recent summers is this southerly tracking jet and the disappearing act of the Azores high which has been displaced much further to the sw, no doubt the Azores high will return in good time to frustrate winter snow lovers!

For those looking forward to Wimbledon it looks like a dry start to the Championships with at least Monday and Tuesday looking dry and a little warmer. Still some uncertainty though with whether the low to the west will orientate favourably and remain far enough to the west to drive some much warmer conditions north out of Spain. After that low pressure does look to move in again and then its whether the current negative NAO will become much more west based if this happens then this may at least allow a ridge to be forced ne towards the south but unfortunately its hard to see a UK wide warmer and drier spell after this mini drier blip at the start of the week.

I think the best that can be said for the output today is that its at least showing some varying solutions and has moved away from the flat zonal pattern of yesterday, whether we see this more amplfiied pattern survive is another matter. The recent winter has often thrown up more amplified solutions past 168hrs but these have failed to verify, personally I'd prefer to see the ECM trend verify, its been a long time since we actually saw a sunshine and wintry showers type scenario, at this time of year those showers could bring quite alot of rainfall which is certainly needed for parts of the UK aswell as here in sw France where we've had only 30% of the normal February rainfall. The ECM and GFS operational runs are poles apart with the former moving the main PV into Scandi and the latter digging troughing into the mid Atlantic which forces high pressure further north over the UK. Looking at the UKMO further outlook 6-15 day outlook that looks more inline with the GFS output than the ECM with it mentioning the chance of more settled conditions once again. In terms of the possibilities of some snow off that shortwave on Sunday its very marginal, I think for any settling snow you'd probably need some decent elevation but these set ups can throw up surprises, its a shame we didn't see this set up a few weeks back, at that point it could have been a big snow event, its often the way, the best set ups tend to appear at the wrong time of year! Certainly something to keep an eye on, much depends on the intensity of the precip and it's likely to be one of those scenarios where one place might get snow and ten miles away just rain.

Looking at the ECM De Bilt ensembles there decent support for a colder spell in the extended range with the control following the mean and given the set up you'd expect to see colder conditions for northern areas of the UK. http://www.weerplaza.nl/15daagseverwachting/default.asp?type=eps_pluim However we have been here before with the models over amplifying the output in the extended range and then flattening the pattern out as it edges towards the 144hrs mark.

The GFS 18hrs run is in a hurry to sink the high, marked differences between it and the other models with it dropping heights over Svalbard and no sign of any trough disruption. But its the GFS and given the rest of the output and its recent poor performance then hardly worth reading too much into it.

Interesting new trend from the models apart from the GFS. The ECM now goes for some trough disruption at 144hrs, it's gone with one of the few morning ensemble members that suggested that: http://www.ecmwf.int/samples/d/inspect/catalog/samplers/banner/mean_sea_level_pressure_and_temperature_at_850hpa!156!pop!od!enfo!enplot!2012030100!!/ At 168hrs the Azores high moves in but will that verify? I'd certainly look out for the ensembles tonight, will any of those send a shortwave into Europe allowing the ridge to the ne to back west again.

The UKMO at 144hrs breaks with the recent operational trend and shows some trough disruption to the west. http://www.meteociel...=144&carte=1021 Could the unthinkable happen? It's a shame we're seeing these outputs now and not a few weeks back. It's hardly been the most consistent model recently and that 144hrs although interesting is a long shot unless that is the ECM goes with this. The GEM which had a similar trend to the UKMO on its morning output, continues with a similar theme this evening, the NOGAPS also goes for some trough disruption at 144hrs. Hard to see the Atlantic being held back for an extended period of time but just a chance that this might take two attempts, whether any trough disruption leads to some snow hard to say at this timeframe.

You can always rely on the GFS to do this! Unfortunately the bain of the winter continues with low heights to the north and output that would look more like early winter than spring, I do fear when the final strat warming occurs just what the prospects will be for summer in the UK. In terms of the mini cold blip at the weekend hard to say whether that shortwave will produce any snow, if anyones hoping for a miracle there are a few ECM options which follow the GEM trend of some trough disruption to the west, far outweighed however by support for the ECM operational run. http://www.ecmwf.int/samples/d/inspect/catalog/samplers/banner/mean_sea_level_pressure_and_temperature_at_850hpa!168!pop!od!enfo!enplot!2012030100!!/

The 120hrs certainly doesn't look like a quick return to the Atlantic and doesn't follow either their own output or the ECM, must have been some colder options in their own ensembles.

The UKMO have dumped their raw output in tonights fax charts, it looks like they've modified this towardsa deeper shortwave: http://www.meteociel.fr/modeles/ukmo2.php?ech=96&carte=2000

The GFS 18hrs run is good but I think we'd need to see a stronger flow to aid convection off the North Sea, again however we see the problems with a high thats too big for its own good, a smaller high centred over Scandi is much better in terms of holding the Atlantic at bay than this long elongated ridge, especially as the coldest pool of air is often closer at hand in that type of set up and easier to eject westwards in towards the UK. By and large if you put aside the differences in the depth of the shortwave near the UK theres decent agreement on the set up but its what happens with heights to the north after 120hrs which makes a big difference in the longevity of any cold.

If it was earlier in the season and the continent had been colder the ECM 96hrs chart would certainly have my attention. Although some colder air does get into the UK I don't think this can support snow away from the highest ground and this would just be reserved for areas on the northern flank of the low. Even an easterly would be unlikely to deliver given how far east the deep cold pool is.Part of the problem is the original orientation of that Scandi high north/south, a more ne/sw would bring the cold pool further west before the shortwave heads into France and then if the Atlantic held off a bit longer a better chance of getting some of that into the UK. The ECM ensemble maps did have a large variety of solutions on its 00hrs but at this timeframe given its consistency in terms of operational output over the last few days its refusing to back away from a quick return of the Atlantic. http://www.ecmwf.int/samples/d/inspect/catalog/samplers/banner/mean_sea_level_pressure_and_temperature_at_850hpa!168!pop!od!enfo!enplot!2012022900!!/

The GFS 18hrs run has the perfect sausage shaped high but the upper air isn't cold enough on this run to bring those convective snow showers in on that strong easterly flow until very much later. Part of the problem is the original orientation of the Scandi high which doesn't have a deep cold pool ready to be ejected westwards into the welcoming arms of the many snow starved net weather members! The cold uppers are held further to the east and only start edging west much later, in terms of snow chances it does look marginal regarding the shortwave, certainly though higher ground could do very well. Still we can't even be sure of the shortwave heading south and thats still a big obstacle, it's incredibly difficult to overcome past history of these set ups. We all know the rule with shortwaves, don't bank on anything until thats modelled within T-96hrs.

The ECM I often view as the sensible choice between the excesses of the GFS and the less than enthused UKMO. If we just look at the main colder options that have been modelled across the big 3 at T-144hrs since the New Year then the UKMO has failed miserably, two northerlies that imploded and it didn't want to know about the early stages of the February easterly. The GFS has been slightly better than the UKMO but still streets behind the ECM when it really mattered, of course outside of the winter months we don't really view the models with such a critical head. As for next week marginality will be an issue, so I think we'd need the ECM to edge the pattern west, it has already done that this evening, can we squeeze a couple of hundred miles further west tomorrow? That could make a big difference.

I think we should bin the UKMO output as it was clueless during the run up to the February easterly and deserves to be ignored! The ECM/GFS look to offer some wintry potential, I'd like to see though a westwards correction in the ECM. NOAA aren't overly impressed by the evenings outputs: FINAL... MADE ONLY MINOR CHANGES TO THE UPDATE PACKAGE FOR THE FINAL ISSUANCE. THE 12Z/28 CYCLE OFFERED EVEN LESS CLARITY THAN THE 00Z/28 MODEL RUN. THE DETERMINISTIC GFS...GEM GLOBAL...AND UKMET ALL OFFERED DIFFERENT SOLUTIONS THROUGHOUT THE MEDIUM RANGE. HOPEFULLY...THE HEAVY RELIANCE ON THE ROBUST ECENS MEAN AND THE USUALLY STRONG PERFORMING ECMWF WILL ANCHOR THE FORECAST IN THE CURRENT SEA OF DOUBT. It's still a difficult task though to get to either the ECM/GFS 168hrs these set ups don't have a great track record of verifying but certainly the ECM has trended back to its runs of a few days back so lets hope that continues.

Good GFS 12hrs run with a better chance for some snow especially over higher ground. The UKMO unfortunately doesn't want to know although its hard to say what would happen after 144hrs as it still has pressure rises to the ne. Both though disagree with the ECM trend, hard to say whats going to happen with this much disagreement.

A very underwhelming GFS 18hrs run, a brief shot of colder air but nothing much to write home about then high pressure moves in again. Certainly if ever proof was needed that the GFS lower resolution output is a waste of space its the ridiculous amount of changes you get from each output. Regarding any colder prospects, hard to say what will happen until we see the models agree on the orientation and placement of high pressure to the ne and the amplitude of the upstream pattern. Unfortunately the models have moved away from a clean set up of low dropping south through the UK and ridge backing west, one suspects that any cold to the east isn't going to make it far enough west and the UK will be left with a more modified flow with troughing nearby much as the ECM suggests. It's ensemble mean is solidly behind that, again the never ending low heights to the north and the reluctance of the pattern to amplify sufficiently mean that a last taste of wintry weather looks less likely this evening. Whether the next troughing can sink sufficiently to bring another chance is open to debate, after a few days of improving cold potential it's a backward step this evening, we'll see in the morning whether theres a last minute reprieve.