Model Output Discussion 01/09/17

[Newberryone]

45 minutes ago, knocker said:

The ecm in pretty good agreement with the gfs for the weekend

Not alone the weekend, but it would appear in pretty much agreement for next week as well. A lot more amplication on the overnight ECM for next week compared to yesterday's run. Precipitation running well below average for most areas if it holds true. 

[knocker]

[Frosty.]

The Gfs 12z gives us a nice ridge of high pressure early next week so some fine weather for a time, especially further s / e which is then briefly interrupted from the w / nw during the midweek period before our weather then becomes very anticyclonic for a while with a decent settled spell of autumn weather across the uk with light winds, variable cloud and plenty of sunshine with pleasantly warm temperatures by day but with cold nights where skies clear and an increasing risk of mist and fog patches.

In the meantime, low pressure is very much in charge with a cool and breezy mix of sunshine and blustery showers, some heavy with hail and thunder. The weekend looks similar but at least the winds are set to become lighter and the trend appears to be for more in the way of sunny spells and less showers.

Edited September 13, 2017 by Frosty.

[Frosty.]

The GEFS 12z mean, especially longer term is looking increasingly settled with benign autumn conditions under high pressure with light winds, pleasant sunny spells but with cold nights under clearer skies with mist and fog..mists and mellow fruitfulness through the extended outlook if this is right.

[mb018538]

Ex-Jose could do us a favour and encourage the Azores high to build in a bit later on, and send the energy further north. Still helluva lot to play for I. The next week or so.

[Frosty.]

The Ecm 12z shows much better weather next week for most areas compared to this week with a ridge of high pressure building in bringing plenty of fine weather with sunny spells and lighter winds, especially further s / e with just more north-western parts of the uk having some Atlantic weather pushing in for a time following a fine spell early next week and looking ahead to day 10 and beyond it continues largely fine and benign across the uk with variable amounts of cloud and sunshine followed by chilly nights where skies clear with mist / fog patches..the friendlier face of autumn compared to the wet and windy conditions!

Edited September 13, 2017 by Frosty.

[Summer Sun]

1 hour ago, mb018538 said:

Ex-Jose could do us a favour and encourage the Azores high to build in a bit later on, and send the energy further north. Still helluva lot to play for I. The next week or so.

Maybe for a time but I think the east will see a slower progression to something more settled

[knocker]

The anomalies this evening are in the same ball park and not looking too bad.

The key features of the upper pattern relevant to the UK are the strong east European ridge that stretches into the eastern  Arctic, The Greenland trough and the other trough to the south east in Central Europe. Thus a quite strong westerly upper flow over the central Atlantic which then splits in the east with part tracking north and resulting in a much slacker flow over the UK. running down to the European trough. Thus pressure on the Azores HP from the energy emitted upstream is much reduced and it can ridge more in the vicinity of the UK. This portends much more settled weather with the north catching the brunt of any systems that nip along. Temps around average but a fair diurnal variation.

Into the ext period there is not that good agreement but the signs are quite positive with perhaps the Atlantic trough retrogressing a tad and the dominate features still remain the east European ridge and positive anomalies north of the UK with the continuation of a slack flow over the UK. They vary on how much influence the Azores will have in the vicinity of the UK, the EPS which I can't post being the most bullish I wouldn't like to hazard a guess at this range vis surface details but suffice it to say in general it looks quite a benign scenario with light winds and temps picking up a tad.

 

[knocker]

With the recent low well away in the east for the next two or three days the the UK will be in a north westerly airstream, veering northerly, thus a showery regime for all but particularly the north and west, some of which may be thundery with hail. With the Azores high pressure ridging to the west and gradually moving east the wind will abate and the showers become much less by the weekend.

By Sunday the ridge is trending more to the north east under the combined pressure of the trough in the west and the low pressure area to the east resulting in most of the UK becoming drier and more settled with just the south east still retaining some showery activity.

Under pressure from the trough in the west the ridge gradually subsides as weak  fronts cross the country before the next little low tracks north east across Scotland  bringing some wet weather with it Tuesday evening and elsewhere on Wednesday as the associated fronts track south east

Then ensues a brief battle between the trough/Azores aka the cooler and warmer air to the west which the former wins hands down and the next quite deep low arrives by the end of the week which could bring some nasty weather , including severe gales, to the north. But that is a long way off and should merely be noted at the moment I feel.

So all in all not quite as benign as one would have expected next week with the upper ridge to the east and north not aligned to mitigated eastwards tracking of the troughs. Need to see the GEFS and ecm before attributing too much confidence in this evolution

Edited September 14, 2017 by knocker

[knocker]

Interestingly the ecm does stick more to the anomaly script next week with the energy/upper flow being diverted north east and thus the systems tracking like wise allowing the Azores to hang in there and remain quite influential  Apart from the odd wobble when a system sneaks in from the south west it just about manages until the end of the run when a large deep trough is parked south of Iceland with the associated troughs orientated N/S down western Ireland. So next week becoming predominately dry apart from Friday but the detail for the week is a long way from being settled.

[Summer Sun]

UKMO shows high pressure never really getting over the UK parts of the south may see some longer drier spells for a time but on the whole, no significant spell of settled weather is shown

[knocker]

The EPS anomaly this morning would appear not to be at odds with the det. output.

[Summer Sun]

UKMO is by far the least promising for high pressure to build t168 shows a westerly flow back with some rain

[knocker]

A fairly dry 10 day outlook

[mb018538]

ECM also sends the energy over the top allowing the high to build and quieten things down...could be quite nice if it comes off.

[knocker]

One point of interest on this evening's ecm. At T216 it has the main trough to the NW linking to the remains of Jose to the south. The resulting fairly lengthy trough severely disrupts the jet which flows NNE along the eastern flank of the trough touching 160kts before swinging south of Iceland.which appears to facilitate the formation of a high cell adjacent to the UK. Merely of interest As I'm not suggesting this is likely.

 

Edited September 14, 2017 by knocker

[mb018538]

ECM also sends the energy over the top allowing the high to build and quieten things down...could be quite nice if it comes off.

[knocker]

Without going into detail there would appear to be nowt significant in last night's NOAA, EPS and GEFS anomalies that differs from the last recent assessment. The outlook from next week until the end of the 14 day period could be a lot worse for most of the UK with the north as ever not quite so lucky.

So back on the farm a continuation for the next couple of days of the cool. showery. N/NW airstream with occasional more organized showery activity as toughs make there was south, as like this morning in parts of the south west. Wales and the Midlands. By Sunday the high pressure nudging in from the west will become more influential so the winds will abate and virtually die out, albeit not completely.

By Monday the ridge is established over the UK so drier and more settled weather pertains but it is also the signal for the perennial battle of the warmer Azores air and the upstream energy driving the trough and cooler air from the north west and by 00z Wednesday the ridge is under pressure with trough(s) to the NW and fronts approaching western Ireland. Over the next 24 hours these make little headway east as a wave develops on the front and tracks north east into Scotland accompanied by a period of persistent rain.

By midnight Friday the low is well away to the north and once more the Azores gains a foothold whilst at the same time a large, quite intense, depression tracks slowly north east to be south of Iceland But the associated fronts from this large system struggle to make any headway east and in fact only manage to impact the north west. This is ostensible down to something that has been mentioned previously and that is the increasing influence of the east European ridge stretching north west and the Atlantic flow becoming meridional thus virtually halting any west-east movement.

So in a nutshell, apart from a blip midweek, next week pretty dry for most until the weekend when a definite NW/SE split materializes. Temps around average but a fair diurnal and latitudinal spread,

 

 

 

 

Edited September 15, 2017 by knocker

[knocker]

The ecm has the wave forming on the front next Wednesday but tracks it north further west and it misses Scotland. But the next one is further east and by 00 Friday is over the Irish Sea with the front orientated N/S along the same. Some quite intense rainfall for N. Ireland, N. of England and Scotland as this tracks east into the North Sea over the next 24 hours. Thereafter the major trough grinds to a halt out west and basically a similar point that I made vis the gfs.( Excuse the coulour scheme). All subject to revision of course.

Edited September 15, 2017 by knocker

[knocker]

The upper pattern indicated by the EPS anomaly this morning is not unexpected and in general fairly good news.

The Greenland/ Atlantic trough is slow moving in mid Atlantic thanks in no small measure to the east European high pressure ridging into the eastern Arctic which effectively splits the upper flow in the eastern Atlantic diverting some NNE. Thus a much slacker flow over the UK and room for the Azores high pressure to be more influential, Thus systems struggling to make headway east and a drier and more settled spell for the UK with temps rising to around average. The north may not be quite so lucky.

In the ext period the pattern does become less amplified (not unusual) but with trough weakening and the Azores still ridging in the vicinity the dry spell will continue with perhaps the temps nudging a tad above average.

A way to go Sidney. No need to store too many nuts for this winter.

 

Edited September 15, 2017 by knocker

[Summer Sun]

Need to keep an eye on the low at t144 over NW Ireland/Northern Ireland could produce a spell of strong winds for those parts

Further SE into England things should begin to warm up as winds turn south westerly

[Man With Beard]

ECM clusters show a risk that the high pressure building in the D8-D10 period could be lost by it building too far north:

[mb018538]

Must be the first time in quite a while we've had a deep trough over the western half of the USA too...hopefully our own semi-permanent are of low pressure can keep out west for a while and give us a quitter spell.

[knocker]

Not much different with this evening's gfs from this morning. Still the front and shallow wave crossing the country Wednesday and then the battle between the trough and the Azores as  the upper flow backs south westerly with the latter hanging in there and winning.Quite delicately poised.

[knocker]

The ecm just about has the wave effecting N. Ireland,Scotland and N. England next Weds, but the front itself gets no further  East than Ireland although another shallow does form on it to be just SW of Cornwall at 06 on Friday. So a pretty dry and settled week apart from Sunday in the south east and the aforementioned areas midweek. Temps varying around the average.

Edited September 15, 2017 by knocker