Model output discussion 14/04/18

[Frosty.]

An encouraging trend next week from tonight's Ecm 12z ensemble mean which indicates the jet stream being pushed to the nw / n and the azores high ridging in bringing increasingly fine and pleasantly warm conditions at least across the southern half of the uk.

[bluearmy]

Gfs modelling picking up on a possible GOM hurricane in the 10/14 day period. is that a tad early ??

[mb018538]

The models are all starting to firm up on the idea of a big Greenland/arctic high forming in around a weeks time...

http://www.meteociel.fr/modeles/ecmwf/runs/2018050900/ECH1-192.GIF?09-12

Never a great thing to see at this time of the year.

[Alexis]

Unless it leads to a Scandi High down the line.

[Djdazzle]

1 hour ago, mb018538 said:

The models are all starting to firm up on the idea of a big Greenland/arctic high forming in around a weeks time...

http://www.meteociel.fr/modeles/ecmwf/runs/2018050900/ECH1-192.GIF?09-12

Never a great thing to see at this time of the year.

I’d rather it happened now than in summer.

[mb018538]

34 minutes ago, Djdazzle said:

I’d rather it happened now than in summer.

Of course, though sadly the weather doesn't work on a credit based system!

We seem to have been stuck with a lot of northern blocking during recent summers which have led to some fairly dodgy weather. July, August and September were pretty bad last year.

[danm]

23 minutes ago, mb018538 said:

Of course, though sadly the weather doesn't work on a credit based system!

We seem to have been stuck with a lot of northern blocking during recent summers which have led to some fairly dodgy weather. July, August and September were pretty bad last year.

The first half of July last year was very warm and sunny. Went downhill after mid month and August was a lot cooler.

[Frosty.]

Late May will be lovely according to the Gfs 6z..

[stodge]

Afternoon all :)

Unfortunately, the daily update running slightly behind schedule but no matter. A cooler but still very pleasant day here in London Town but a sense perhaps of a change back to something more typical for mid May than the current July-like conditions.

On to the models and the medium term analysis to Saturday May 19th:

ECM 00Z at T+240:

http://www.meteociel.fr/modeles/ecmwf/runs/2018050900/ECM1-240.GIF?09-12

On the face of it, not too bad with a ridge of HP covering most of the British Isles. ECM has the weekend LP disrupt and fill over Ireland but the key development is the return of strong northern blocking as a large 1045MB HP sets up over eastern Greenland. The jet is moving back south in the face of this and Atlantic LP systems are going to be moving through the British Isles which means more rain and wind for most.

GEM 00Z at the same time:

http://modeles.meteociel.fr/modeles/gem/runs/2018050900/gem-0-240.png?00

GEM was the most anticyclonic of the models yesterday but today has come more into line with ECM. After the weekend LP disrupts and fills a new LP develops over Scotland briefly but that too fills in the face of rising pressure from the north and east. As the ridge builds in from the east, the Atlantic LP stalls in situ so a warm and largely settled outlook for most with only the far west of Ireland seeing drizzle.

GFS 00Z OP at the same time:

http://modeles.meteociel.fr/modeles/gfs/archives/2018050900/gfs-0-240.png?0

A very soggy and unpleasant chart especially for the south with rain, possibly heavy at times, for southern parts. It's quite a messy evolution this morning from the American model and not really in sync with ECM/GEM. After the weekend's LP fills, there's an attempt to raise pressure from the SW but by Tuesday next week a new LP is developing to the NW and squeezing out the heights. Meanwhile, pressure is rising strongly to the far NE and all that does is push the complex trough down across the British isles by the end of the week. Further into FI and the British Isles essentially is in the col between two competing pressure regimes. To the west, we have the traditional LP to the north and HP to the south but to the East we see HP over Scandinavia and LP over Europe so you'd think the Atlantic trough could drop SE through the British Isles or the HP could ridge NE but in essence neither happens.

GFS 06Z OP at T+234:

http://modeles.meteociel.fr/modeles/gfs/runs/2018050906/gfs-0-234.png?6

Variation on a theme albeit with the small LP about 700 miles further north. Further in to FI and it's a pattern we often see at this time of year as thundery LP heads north from Africa and Iberia toward southern Britain forcing the Azores ridge NE over northern Britain and we end with a warm and dry E'ly albeit with a hint of thunder for the Channel Islands.

GEFS 06Z at T+240:

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=240

The spread to the NW tells the story between those members who favour a continued Atlantic dominance of our weather and those who look at northern blocking and a more continental influence. The OP went with the latter but the Mean plays the col card which isn't unsupported either. Further on and it's the same old story of the strong signal for northern blocking so we'll see.

In conclusion, the pattern through to the weekend and beyond looks set. GFS has quite a messy evolution which doesn't end well for the south while both GEM and especially ECM bring in strong northern blocking which pushes the jet back south. It's far from a washout but with LP systems tending to move across the British Isles rather than to the north we would get quite unsettled and wet spells. There are also hints of low heights from the south coming north which isn't unknown at this time of year and can bring thundery downpours but that's looking more toward the last third of the month and wouldn't be unusual.

[cheese]

2 hours ago, danm said:

The first half of July last year was very warm and sunny. Went downhill after mid month and August was a lot cooler.

August had average temps and above-average sunshine here. Definitely not bad.

Edited May 9, 2018 by cheese

[Man With Beard]

A pretty dramatic difference in the two D5 clusters

The eventual result isn't too dissimilar though - the main Atlantic trough stays west and ridging from the Azores has a fair amount of success in punching towards Scandi, eventually getting here by D10

However the northern blocking cluster eventually sends the trough through to the UK as we enter the final third of May. The main cluster remains dominated by ridging from the SW through the UK.

[carinthian]

On ‎08‎/‎05‎/‎2018 at 09:41, carinthian said:

Nice to see many parts enjoying the high temps across Blighty yesterday. Highest temps seem to have been along an axis , say from Dorset to Yorkshire.  Our medium term charts continue to show, yes, a cold pool development early next week over parts of mainland Europe. A moderate snowfall at elevation in some Alpine regions (we have been issued a warning ). Looks southern Britain could be in the influence of a continental cyclonic flow by 144t/168t, maybe mixed with a warmer air mass from the east. Northern Britain  getting the best of any sunshine and nice temps. Certainly, interesting Spring weather this season with some extremes, especially across Britain.

C

This latest 500mb temperature profile from UKMO at 144t sort of ties in with our earlier thinking( re above post ) A developing upper cold pool projected to move slowly ESE from SW Britain towards the Alpine region for this time next week. Snow is still in our forecast with probable freezing level around 6500 feet based on this picture. SE Britain likely to have some showers early next week and rather cool temps with a gradual improvement to warmer sunnier conditions in the days 7-10 forecast period. Possibly NW Britain getting the best of the weather in that flow. 

C

Edited May 9, 2018 by carinthian

[mb018538]

Looks pretty ropey to me with that small low causing headaches. From my experience they can linger for days and give plenty of crud weather for a lot of people. Hoping it’ll do on sharpish!

[Mike Poole]

Different sort of post from me tonight as we wait to see where we're headed now.  The Met Office update refers to slow moving pressure patterns and I think this is best illustrated by a north hemisphere view of 500mb height anomalies.   Here's GFS 12z to T192:

And from there to T384:

Obviously the detail not relevant this far out, but it sort of illustrates  the slow moving dogs breakfast over the north hemisphere.   But the good news is there doesn't seem to be an obvious rut the UK can get stuck in.  Significant high anomaly over the pole at times.

[summer blizzard]

GFS with a pretty strange forecast for tropical anomolies. 

Stronger easterlies around Indonesia but stronger westerlies around the east Pacific.

[Mike Poole]

Pretty strong signal on the GEFS 12z mean for a UK high at the end of the run, normally these charts at 16 days are an averaged out mess, maybe it's on to something?

[Frosty.]

Looking longer term there is some good news this evening from the GEFS 12z mean with the jet further northwest / north and high pressure building in which is what happened with the Gfs 6z operational this morning..so potentially late may could be settled and warm.

Edited May 9, 2018 by Frosty.

[Lincs Observation]

41 minutes ago, Frosty. said:

Looking longer term there is some good news this evening from the GEFS 12z mean with the jet further northwest / north and high pressure building in which is what happened with the Gfs 6z operational this morning..so potentially late may could be settled and warm.

Looking. Good at the moment for another cracking bank holiday end of May, could it be possible ? We just might be in with a shout all be it a small shout at this range.

[Frosty.]

This evening's  Ecm 12z shows a slow moving pattern which is neither settled or unsettled, it's somewhere inbetween which makes it changeable with some rain, some showers but also some dry and sunny periods and after tomorrow's nice ridge of high pressure a more breezy few days on fri into the weekend but then at least the winds become generally light next week so in the dry and bright / sunny spells it would feel pleasantly warm..could be worse!

Edited May 9, 2018 by Frosty.

[Mike Poole]

Not many posts in here tonight, maybe understandable given the op runs tonight, let's get the bad news out of the way first, GFS precipitation to T240:

ECM T240 all too shabby!

Here's the ECM ensemble mean across the NH at T240, couple of footprints from Bigfoot:

But still average in terms of UK conditions, some good runs and bad ones I would think.

Finally FIM9 is on our side with a nose of high pressure at T240:

[mb018538]

That amount of high pressure to the north only usually does one thing - force the low pressure and jet south over us. These sort of set ups can give a lot of rain if lows/fronts get stuck over one place for a long time....hoping for a best case scenario!

[CheesepuffScott]

2 hours ago, Frosty. said:

Looking longer term there is some good news this evening from the GEFS 12z mean with the jet further northwest / north and high pressure building in which is what happened with the Gfs 6z operational this morning..so potentially late may could be settled and warm.

Hope so, I am in Weymouth for the bank holiday weekend and it'd be nice if I were lucky and it is warm. Every other time I've booked time away, it's always been 'meh' weather!

[Frosty.]

Actually, looking at tonight's Ecm 12z ensemble mean, most of next week doesn't look bad at all, its a very slow moving pattern, there is some ridging and winds become generally light and apart from a few showers dotted around i expect there would be plenty of dry bright weather with sunny spells, especially further south and pleasantly warm temperatures returning following a cooler blip.

Edited May 9, 2018 by Frosty.

[Fourty Point Three Degrees]

13 minutes ago, Frosty. said:

Actually, looking at tonight's Ecm 12z ensemble mean, most of next week doesn't look bad at all, its a very slow moving pattern, there is some ridging and winds become generally light and apart from a few showers dotted around i expect there would be plenty of dry bright weather with sunny spells, especially further south and pleasantly warm temperatures returning following a cooler blip.

I guess you missed the GFS 12Z op and ensembles from GFS towards a cooler and wetter regime  North Western Wales which was chilly, cold and damp all the way though.  The ECM 12Z op was also quite poor with a worrying mobile jet set up developing across the Atlantic. I think now summertime is approaching the models are spotting the '8' in 2018!!! 

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=307&y=176

          

Edited May 9, 2018 by 38.5*C

[Frosty.]

Just now, 38.5*C said:

I guess you missed the GFS 12Z op and ensembles from GFS towards a cooler and wetter regime  

          

No I didn't miss anything...I'm just commenting on the Ecm 12z ensemble mean, and also just seen the latest bbc news 24 weather outlook for next week, doesn't sound bad at all for most of the uk with some azores ridging.