Model Output Discussions 12z 01/06/2017

[knocker]

The last couple of runs has seen the GEFS anomaly move fairly significantly to weaken the trough to the NW and push it east whilst initiating more positive anomalies and some ridging in mid Atlantic, This not only supports to some extent the det output but even suggests a settled period of perhaps longer duration. Await NOAA and the EPS with some interest for any support, particularly the latter as it do date has not been over keen on this scenario and rather liking keeping the Azores HP firmly in the SW

Edited August 15, 2017 by knocker

[Summer Sun]

London ens looking much drier from Saturday

[knocker]

Nothing conclusive vis NOAA and the EPS this evening but they are not as bullish as the GEFS in the long term. Certainly positive anomalies and some ridging in mid Atlantic in the ten day time scale which would indicate a few days of HP influence except perhaps for the far north but no great suggestion that it will be sustained for long after that period so maybe the GEFS over egging it a tad. At least it does look like a better outlook without going overboard.

[Man With Beard]

EC clusters this morning was not completely convinced of a settled period for mid-next week, but this evening's set was much more settled with varying degrees of warmth. Until a couple more ensemble sets get fixed on a particular direction, best keep the bullish outlook and the more doubtful outlook in mind. But glasses definitely half full rather than half empty for a dry, sunny and warm period for all, at long last!!

EC clusters 00Z for T192

EC clusters 12Z for same timeframe:

[knocker]

Nothing constructive to add to last night's assessment of the anomalies so straight on to this morning's gfs.

Actually a quick look at today and tomorrow, Most places will stay dry today but the next low is on it's way to the NW and the associated fronts (I say this advisedly) will cross the country later bringing a fair bit of rain mainly to northern parts,

The low tracks east and is still effecting northern parts on Friday but this then gives way to to transient ridge on saturday. I say transient because by 12z Sunday Gert is south of Iceland and the associated fronts are bringing rain to all but the far south.

From this point things get quite interesting, The amplification of the Azores in mid Atlantic (something the gfs is quite keen on) gets underway initiating the track of Gert to be adjusted east and then east south east over the next 48 hours resulting in some quite inclement windy conditions over Scotland with the probability of gales. By the end of that period the aforementioned Azores HP has moved east over the UK

For the rest of the week the Azores dominates the Atlantic but with the UK being on the eastern periphery we may well catch systems swinging around the high cell, particularly Scotland, although nothing of any great note. The N/S tendency in these situations is quite well illustrated by the rainfall

 

[knocker]

The ecm is not dissimilar to the gfs up to the weekend but at 12z Monday it still has the filling Gert out to the west and another frontal system impacting the north' It then tracks the low across Scotland en route to Denmark where it resides at 12z Wednesday. Simultaneously the Azores HP centred to the south west ridges NE as far as west of Norway. Any thoughts of building on this are thwarted by a new trough arriving over Scotland.

Thus not hugely different to the gfs but the intensity and orientation of the high pressure in the Atlantic post the travels of Gert still to be sorted.

[karyo]

Looking at the SSTs, there is quite a notable cooling taking place across the enso region. This region is coming closer to La Nina territory so I wonder if the models will start factoring this with a cooler September than first thought.

[mb018538]

6z is pleasant enough, a slightly better variation on the 00z theme - which is to be expected in this kind of situation. The position of the high all crucial.



Looks like these tropical systems are like buses....wait for one and two come along together! All eyes on the Caribbean and North Atlantic, as by day 10 we could have another system to meddle with the jet stream once more and throw everything into chaos.



Keep those eyes peeled folks.

[NorthernRab]

Sorry but couldn't resist.

 

 

First snow of the season appears on the GFS 6hz!   

 

[Iceaxecrampon]

GFS Sunday

OK IM (and possibly flooded) BY and others up here but there you go anyway.

 

 

Edited August 16, 2017 by Iceaxecrampon

[Matthew.]

UKMO has some dreadful charts for early next week. This weekend looks better with Sunday the least windy. Just started getting hopes up for a settled period but now looks very different.

[stodge]

Afternoon all

More evidence of mid-Atlantic ridging combined with Greenland heights on the evening models. Here's the GEM 00Z OP at the end of the run:

GFS OP takes it much further and puts the British Isles in a cool unsettled N'ly or NW'ly for the Bank Holiday.

 

[mb018538]

Hmmmmmm....when we need an it of low pressure help we don't get any!! Looks promising by day 7ish, but quickly goes pear shaped as the high gets pulled west. We really need a low to push in and stop the retrogressing high....but we will see. Could easily end up with a trough parked to the east and northerlies.

[blizzard81]

30 minutes ago, mb018538 said:

Hmmmmmm....when we need an it of low pressure help we don't get any!! Looks promising by day 7ish, but quickly goes pear shaped as the high gets pulled west. We really need a low to push in and stop the retrogressing high....but we will see. Could easily end up with a trough parked to the east and northerlies.

Yep, a coldies  winter dream chart for the August bank holiday. Great! Really sums up this damp squib of a summer. 

[knocker]

Just to emphasize yet again why next week, and in particular the handling of Gert, is a long way from sorted and you need to look no further than this evening's ecm.

Midday Monday sees that the low which is the result of Gert is west of N.I at about 20W with associated fronts just impacting the north west.

It then tracks the low slowly east over the next 48 hours to be in the North Sea just east of Scotland by 12z Wednesday, So a showery couple of days with the odd longer period of rain.

By Thursday 12z the low is over southern Norway and the Azores is starting to ridge north east.

As mentioned at the beginning next week remains a lottery until the track of Gert is sorted

Edited August 16, 2017 by knocker

[ANYWEATHER]

Evening All hope you all had a good day  Stark differences between ecm and gfs at t+168 which of course can be expected at any time of year but at this time of year the models are in complete mayhem because of tropical disturbances etc. Fun watching nonetheless

[Singularity]

  

Three models, three markedly different rates of progression with respect to the low containing the remnants of  Hurricane Gert.

Not often you see UKMO and ECM so far apart at 5 days range.

Once, the fastest outcome looked the best with a ridge building in behind, but GFS has been tending toward holding that ridge back to the west anyway so it's lost its charm there. The slowest outcome - i.e. ECM - does at least offer a potentially very warm Monday followed by a thundery breakdown on Tuesday that would likely prove entertaining for a fair few on here. That the low remains slow-moving in our vicinity afterward... well we're getting used to that as the atmosphere just keeps on resisting any break away from a La Nina-like tendency; the GEFS mean for the Pacific 850 hPa winds has reduced the extent and magnitude of positive zonal wind anomalies i.e. weaker than average trade winds for the week ahead and that's not helping with trying to get a ridge to take hold in a position NE of the Azores rather than over or NW of there.

It's been fascinating in a horrific sort of way to see these trades just keep on coming back strong. We had such a lengthy Nino-like atmospheric state lingering on after the oceanic El Nino event of 2015-16 and it does seem as if the atmosphere is determined to balance things out even if the ocean refuses to fully embrace a La Nina condition (anomalies remain inconsistent spatially, with more of those positive-negative 'waves' in the anomaly patterns). With the broader atmosphere still managing to be impressively warm in the absence of a Nino oceanic setup, perhaps we should not have been so taken aback to see these strong trades... speculative I know, but it's as good as I can come up with for now 

[knocker]

Not sure there is much to be gained by getting too hung up on the anomalies post Gert at the moment as consistent they are not as a quick glance at the last two NOAA charts will illustrate. Suffice it to say they are currently all in the same ball park which would indicate that the percentage play is a more settled spell with Azores HP to the SW/W becoming more influential but as ever the precise orientation and intensity of the surface high will be key to the detail and duration vis the UK (the EPS is not dissimilar to the GEFS)

So on to the gfs this morning.

The current low the NW tracks ESE to be just off NE Scotland by 12z tomorrow with the UK in a showery north westerly  This gradually moves away towards Norway on Saturday as a transient ridge nudges in briefly on Sunday but by 06z on Monday the next low (ex Gert) has arrived ENE of the Hebrides with associated fronts across the north west. What happens next is perhaps the key to the rest of next week and in the next 24 hours the gfs deepens the low somewhat and runs it down to the east North Sea diving a pretty inclement day on Monday, particularly in the north before the surface wind veers northerly as the high pressure that has been amplifying to the west tracks a little east.

For the rest of the week the HP is in charge before retrogressing towards the end of week leaving the door ajar for troughs to swing around it and SE towards the UK a scenario that this morning's GEFS would not appear adverse to. An illustration of the importance of the orientation of the surface high cell

 

Edited August 17, 2017 by knocker

[knocker]

The ecm still not in agreement with the gfs vis the handling of Gert which at this range is not brilliant. At 12z Monday it has the center of the low much further west with the fronts just effecting NI and NW Scotland. In the next 24 hours the low drifts slowly east with the rain only impacting the northern half of the UK. It then turns NE and the Azores ridge pushes in from the south west and still only the north west within the circulation of the low.

But the Azores HP does not amplify to the west as with the gfs and the UK stays in a general westerly flow with a classic N/S split. as any systems traveling east only impact the north.

So out of all this the southern half of the UK remaining dry and perhaps quite warm the beginning of the week with again the north being unfortunate regarding rain.

[Man With Beard]

ECM op looks like dodging the worst of Gert by T120

But on the ensembles it was in the smallest of 6 clusters, and all other clusters had Gert more influential at the same timeframe.

[Matthew.]

A sneak peek at the winter forecast from BCC with Gavin P.

[karyo]

16 minutes ago, Matthew. said:

A sneak peek at the winter forecast from BCC with Gavin P.

Does he give the reasons for this forecast?

Couldn't be more different to GLOSEA.

[Summer Sun]

Next week starts unsettled but by Tuesday we have the first hints of high pressure starting to build in

By mid week it drifts across all parts

[The PIT]

Interesting GFS 12oz very close to last nights ECM at T240. Not often you see things so far out that close.

[mb018538]

Models all over the place again....UKMO and ECM vastly different at 120/144 hours.