Model Output Discussion 12z 23/05/13

[Frosty.]

That is very interesting because a long range forecaster, Ken Ring at www.predictweather.co.nz has predicted that this Summer will be similar to that of 1995 with the heat starting in the end of June.

Let's hope so, we are long overdue a good summer, early signs are promising with high pressure set to feature a lot more on both the ecm and gfs 12z runs today, also the gefs 12z mean is excellent in FI with the azores anticyclone building strongly towards and through the uk.

[Methuselah]

That is very interesting because a long range forecaster, Ken Ring at www.predictweather.co.nz has predicted that this Summer will be similar to that of 1995 with the heat starting in the end of June.

Are the models gearing up for a re run of 1995?

Not really. At least, not yet...They might be gearing-up for a re-run of Ken Ring, though!

[ANYWEATHER]

That is very interesting because a long range forecaster, Ken Ring at www.predictweather.co.nz has predicted that this Summer will be similar to that of 1995 with the heat starting in the end of June.

Are the models gearing up for a re run of 1995?

In short No, but there other threads for this!!   

[Frosty.]

That is very interesting because a long range forecaster, Ken Ring at www.predictweather.co.nz has predicted that this Summer will be similar to that of 1995 with the heat starting in the end of June.

Are the models gearing up for a re run of 1995?

It's too early to say but it does look like a better early summer than last year at least, despite what the met office update said today, there is a lot of positives from the extended ens mean output for a lot of good weather during June.

[Thundery wintry showers]

Looking back over the last number of years, excluding last year, western areas have tended have the better weather in June, while August weather has tended to be better in the east.

 

Also in sheltered SW areas, temps can be better than average in these setups in any sunshine. In any case I'd take the current forecast weather over Last June, even if it does mean wet days like the one forecast for Monday,

Indeed, a good point, sheltered SW areas sometimes come out warmer than average and I think this is also true for much of Ireland and western Scotland, depending on how close the high ends up.

I think it's always been normal to some extent for western areas to have their sunniest and driest weather in May/June before enhanced westerlies bring a higher frequency of cloudy damp weather in July and August, while conversely sheltered eastern areas don't see a significant drop in average sunshine amounts.

 

What you say is very interesting, how did the second half of 1995 play out weather wise?

Summer 1995 was one of the famous scorchers.  Around mid-June 1995 the mid-Atlantic high toppled south-eastwards allowing westerlies and weather systems to head in between the 16th and 20th, but then the high built northwards and brought a spell of hot dry sunny weather to most parts in the last third although low cloud sometimes affected the eastern side of England.  July 1995 had a Euro high/Atlantic trough setup and was consequently hot and sunny for most with some thundery outbreaks and then in August the high was mostly centred on top of the British Isles and we ended up with one of the hottest, sunniest and driest calendar months since reliable records began. 

 

I think it's worth flagging up the June 1995 instance for the benefit of those who feel that a summer that starts off with northerlies and a mid-Atlantic high can't develop into a scorcher.  Summer 1989, which in some regions was comparable sunshine-wise to 1976 and 1995, also started off with a mid-Atlantic high and frequent northerlies.  However we have also had summers that started off cool and relatively dry with northerlies and turned into washouts, so as is often true in meteorology, the upcoming pattern doesn't say a lot about how the rest of the summer will turn out.

[Frosty.]

I would be more than happy to settle for what the Ecm 12z is showing tonight, it's a huge upgrade compared to last night's 12z trough fest, this run shows high pressure building strongly by later next week and most of the uk has a spell of fine and warmer weather but it's not plain sailing, there are a few flies in the ointment in the form of shallow troughs or weaknesses which would increase the risk of showers but in general it's a good looking further outlook, the ecm 12z looks rather warmer than the gfs 12z run in FI.

 

The nadir of the ecm 12z run is T+120 hours with a trough directly over the uk but from then on, it's an improving picture with high pressure gaining the upper hand.

[Frosty.]

Tonight's GEFS 12z mean is one to BANK, it eventually shows a prolonged spell of warm and settled weather thanks to the strengthening influence of the azores anticyclone, early to mid June could bring a welcome spell of summery weather to most of the uk after a sticky start, add this to the much improved ecm runs today and we appear to be on the right track.

[Gibby]

Good evening. Here is the report of the 12z output from GFS, UKMO< GEM, NAVGEM and ECM for today Friday May 24th 2013.

All models show the Low pressure close to SE England this evening filling and moving away South overnight taking it's showers and strong cold winds with it. In it's place comes a rare visitor to our shores in the shape of a ridge of High pressure crossing gently East over the weekend giving rise to dry and fine conditions with sunny spells and temperatures back up to the seasonal average though with chilly nights. On Bank Holiday Monday the weather will deteriorate again as a deepening Low pressure moves close to NW Britain pushing troughs East over the UK through the day.

GFS then takes us into the shortened working week with a complex area of Low pressure over or close to the UK moving SE with rain or showers through the midweek period before winds settle Northerly at the end of the week in response to High pressure close to Western Ireland. Over the weekend the high remains in situ maintaining a cool Northerly flow over Britain with some showers scattered around. Little overall change to this pattern of High to the West and NW and Low to the South and East sees winds continuing to blow from between North and East with occasional showers, especially in the South but a lot of dry weather too but never overly warm.

The GFS Ensembles, though rather warmer than currently show nothing remarkably warm in the next few weeks. Temperatures look more likely to be close to average at best and with rain spikes scattered about throughout the run, especially in the South High pressure looks favoured to persist to the West and North with showery Low pressure to the East and South.

The Jet Stream shows the flow moving SE over or to the West of the UK over the coming week before the flow breaks down to become weak or almost non-existent towards the end of next week.

UKMO shows a NW/SE split at the end of it's run following an unsettled midweek period with rain or showers. These will become confined to more SE areas at the end of the run with NW areas seeing drier and brighter conditions in association with a weak ridge close by.

GEM shows an unsettled spell too for the early and midweek period of next week with rain or showers. It takes until the weekend before marked improvements begin to take shape in the form of High pressure moving up from the SW with a gradual transition to dry and warmer conditions with light winds to end the run.

NAVGEM shows very unsettled conditions next week with rain and showers for all as Low pressure slips South close to the South by Thursday and away SE by the weekend with a slack NW flow with just scattered showers taking over at the weekend with bright or sunny spells and average temperatures.

ECM tonight also shows an unsettled spell through the middle section of next week before High pressure from the Azores tries hard to achieve a link with the High well to the Northeast of the UK next weekend. While not ideal for the South many Northern and Western areas would become drier next weekend while an upper air disturbance promotes shower formation over SW areas. However, a good deal of dry and settled weather could develop in the South too with sunny spells and just slack Northerly winds. By Day 10 High pressure has centred between Scotland and Iceland with a weak ridge from it down over the UK. Fine and dry weather would be likely for all and while not a heatwave some respectable temperatures bordering on warm could develop with time.

In Summary tonight's charts looks like a gradual improvement is on the cards. High pressure does look more and more likely to play more of a role in the conditions over the UK from about a week or so time. Improvements look like being from the NW but it looks like it could be a painfully slow process for Southern Britain to see full benefits from this improvement. With the UK always on the cool side of any High pressure belt shown tonight nowhere will see heatwave conditions in the next two weeks if all tonight's charts verify but a good deal of bright and at times sunny weather would likely develop which many people will settle for. It maybe though that a weakness in pressure either over or close to the South of the UK could scupper these improvements down here as many charts including the GFS Ensembles show showery Low pressure close by to the South.

[Summer Sun]

We are getting back on track again today with the ECM ensemble building pressure strongly as we head into June

 

 

Until its within the t144 range and lower we still need to be cautious but its positive steps again after a wobble for a few days

[NeilN]

We are getting back on track again today with the ECM ensemble building pressure strongly as we head into June

 

 

Until its within the t144 range and lower we still need to be cautious but its positive steps again after a wobble for a few days

 

 

I hope this is true. Would be FANTASTIC for June

[snowking]

We are getting back on track again today with the ECM ensemble building pressure strongly as we head into June

 

 

Until its within the t144 range and lower we still need to be cautious but its positive steps again after a wobble for a few days

 

Yep and, crucially, good agreement between the GFS and ECM suites:

 

 

There could finally be some good news on the horizon this evening

 

SK

[Thundery wintry showers]

I think the ECMWF ensemble mean is more convincing than the GEFS mean because the ridge of high pressure is brought closer in (pressure reaches or exceeds 1025mb over most of the country by T+216) and I doubt that cool cloudy weather would be widespread in eastern areas with the ridge getting that close.  This is a stark contrast from previous runs where the ECMWF mean generally had the high further west than the GEFS mean.

[Tony27]

to sum up the GFS 18z      

[049balt]

Indeed, a good point, sheltered SW areas sometimes come out warmer than average and I think this is also true for much of Ireland and western Scotland, depending on how close the high ends up.

I think it's always been normal to some extent for western areas to have their sunniest and driest weather in May/June before enhanced westerlies bring a higher frequency of cloudy damp weather in July and August, while conversely sheltered eastern areas don't see a significant drop in average sunshine amounts.

 

Summer 1995 was one of the famous scorchers.  Around mid-June 1995 the mid-Atlantic high toppled south-eastwards allowing westerlies and weather systems to head in between the 16th and 20th, but then the high built northwards and brought a spell of hot dry sunny weather to most parts in the last third although low cloud sometimes affected the eastern side of England.  July 1995 had a Euro high/Atlantic trough setup and was consequently hot and sunny for most with some thundery outbreaks and then in August the high was mostly centred on top of the British Isles and we ended up with one of the hottest, sunniest and driest calendar months since reliable records began. 

 

I think it's worth flagging up the June 1995 instance for the benefit of those who feel that a summer that starts off with northerlies and a mid-Atlantic high can't develop into a scorcher.  Summer 1989, which in some regions was comparable sunshine-wise to 1976 and 1995, also started off with a mid-Atlantic high and frequent northerlies.  However we have also had summers that started off cool and relatively dry with northerlies and turned into washouts, so as is often true in meteorology, the upcoming pattern doesn't say a lot about how the rest of the summer will turn out.

Thanks for all that and I will confine comments on Ken Ring to another more suitable thread, I await with interest how this Summer develops, .

Edited May 25, 2013 by 049balt

[Gibby]

Hi folks. Here is the report taken using the midnight outputs from GFS, UKMO, GEM, NAVGEM and ECM for today Saturday May 25th 2013.

All models show a pleasant weekend to come as a ridge moves across the UK from the West giving light winds and sunny periods by day and clear, cool weather at night. A weak trough over NW Britain keeps things cloudier here with a little rain. By Monday a deep depression moves SE towards NW Britain with strengthening winds bringing rain East across the UK in association with troughs of Low pressure through the day. On Tuesday and Wednesday all of the UK remain under the influence of this feature as it drifts SE over the UK returning rather cool and unsettled conditions for all.

GFS then shows the latter part of next week under a NW flow. A ridge on Thursday though would give a drier and brighter day with further rain on Friday in rather cool conditions still. Next weekend then shows to be slightly warmer as a warm front crosses NE with a moist and cloudy SW flow following but some brightness and warmth possible in the SE for a time. Cooler and more unsettled weather then returns while a trough crosses East before the end of FI sees a transformation into a warm and sunny spell as High pressure takes complete domination over all areas centred over Scotland.

The GFS Ensembles still show a warming trend this morning and with less rainfall spikes this morning there seems to be a trend towards drier conditions even in the South which indicates better High pressure influence. There is no indication of any heatwave status from the members yet though but most of us will settle from what looks like the chance of a spell of very acceptable weather generally.

The Jet Stream shows the flow still moving SE over or just to the West of the UK. More encouragingly this morning it then breaks up with a weak flow maintained over Southern Europe while the Northern arm moves East over Britain late next week trending North.

UKMO today has improving weather over the UK later next week with Low pressure having moved way off over Eastern Europe with High pressure near the Azores. A slack Northerly flow would most likely deliver largely dry conditions with broken cloud and just the chance of a light shower. Never overly warm though.

GEM holds Low pressure close to Eastern Britain rather longer while meaning a greater shower risk later next week, especially towards the East. A strong High just West of Britain refuses to enter UK air space and maintains it's position just to the NW with the SE under a shallow trough with showers prevalent still here at the end of the run. Still on the cool side for many.

NAVGEM shows a showery NW airflow late next week and into the weekend with cool breezes everywhere. The showers could be heavy with hail and thunder in places, especially in the North. Some decent breezy dry spells may occur in the South with more scattered showers here.

ECM today shows a ridge of High pressure late next week settling things down with sunshine developing widely by Friday as the chilly Northerly aspect to the wind finally dissipates. It will slowly become less cool. With the Jet Stream having moved North towards Iceland the weather finally looks more like Summer for a time as the Azores High stretches across the UK next weekend with long sunny spells and increasingly warm conditions developing for all. However, it might not last long as colder uppers from the North look like infiltrating down over Eastern Britain late in the run with a developing cold pool re-introducing showers from the North by Day 10.

In Summary this morning the improvements I mentioned last night have continued to gain slow momentum this morning with all models except NAVGEM showing at least encouraging signs of improvement in the weather over the UK from the end of next week. Finally it looks like the Azores High may make it's move towards the UK following the exit of the depression from midweek's unsettled period. It isn't going to be a straightforward transition though as there will be various cold pools of upper air scattered about which could scupper things and in any event heatwave conditions look unlikely at this stage. Nevertheless, one step at a time and I think this is the best set of output I have reported on for some considerable time. Let's hope it's maintained for the 12z's later.

[Frosty.]

It's generally very good news from the 00z models this morning, the azores/atlantic anticyclone is set to ridge into the uk later next week onwards with variable levels of success. Having the ecm on board is the biggest plus and the ecm builds a robust looking azores ridge up and across the uk with increasingly warm and summery weather, however, the high pulls northwest and the result of that is we see cooler air spreading down the eastern flank of the ridge and also the risk more cloud and a few showers with a shallow trough to the east, the ecm and gem 00z are remarkably similar by T+240 hours in the positioning of the high and overall synoptics. The Gfs 00z also builds the azores high across the uk but further south which means we end up with a north-south split, northern britain in the atlantic slip stream above the ridge which would make for more changeable, breezier conditions but very good news for the south of britain with higher pressure and lighter winds, the gfs needs a few bites of the cherry to eventually build a strong anticyclone directly over the uk bringing a nationwide very warm and sunny pattern.

So in summary, it's generally a more anticyclonic and rather warmer outlook ahead but still a few pesky troughs to keep an eye on within the overall anticyclonic setup, also there is a tendancy for the high to drift to the northwest of the uk.

Edited May 25, 2013 by Frosty039

[Summer Sun]

UKMO is looking positive this morning with high pressure edging in by the end of next week

 

 

Something ECM also shows

 

 

[Tamara]

As of this morning it seems that the computer models are suggested that the jetstream flattens out at last and thus the Azores High is programmed to move eastwards. There have been a lot of signals in further time periods for this but none of them have been correct. Is this the occasion that it finally arrives? 

 

The further question then would be is it something reasonably sustained or still a changeable mixture of weather? There has not been a proper spell of anticylonic weather since the glorious sunshine and deep blue skies of exactly a year back when we had what was in essence 'our summer'.

 

In the shorter term, we have a reasonable Bank Holiday weekend and then a few days of further showers and rain before, just maybe, the weather settles down a little. There is a definite trend to take the High pressure to the NW of the UK and this will need to be watched in terms of what it leads to. I'm not sure that pressure on the nearby continent will be high enough to prevent a fly in the ointment here in the south and east. However, that it still a little way forward and very uncertain at this time.

Edited May 25, 2013 by Tamara Road

[Frosty.]

Get ready for even better news, the Ecmwf 00z ensemble mean turns into a spectacular run with the azores anticyclone building strongly up and across the uk and bathing the uk in very warm and sunny weather which looks like it would last well beyond T+240 hours, so this is the icing on the cake to almost a full set of models in agreement that we are in for a more settled and warmer spell from later next week onwards, let's hope this trend continues to firm up in the days ahead.

[nitro_deluxe]

Would we be looking at mid 20s Centigrade? Should the above actually pan out...

Edited May 25, 2013 by triple_x1

[Frosty.]

Would we be looking at mid 20s Centigrade? Should the above actually pan out...

Yes, low to mid 70's F (low to mid 20's celsius) or slightly higher would be the result of the Ecm 00z ens mean this morning with lots and lots of very strong sunshine..and no pesky troughs either.

Edited May 25, 2013 by Frosty039

[Tamara]

Would we be looking at mid 20s Centigrade? Should the above actually pan out...

Taken at face value, then current modelling would suggest temperatures a lot warmer than much anything we have seen since last summer but with maybe something of a NE'erly breeze some windward coasts would be kept much cooler with North Sea temperatures still in single figures for the most part. The key part of your post obviously is the 'should the above pan out' part.

[049balt]

What models do the Met use?

[Frosty.]

What models do the Met use?

I think they look at all the models/ens we look at plus their own ensemble model, mogreps.

[049balt]

I wonder why the had a wobble yesterday.