Model Output Discussions 12z 03/05/2016

[Man With Beard]

7 hours ago, knocker said:

I fail to see how but in fact you didn't answer my perfectly reasonable question. You appear to be arguing that changes of interpretation by two deterministic runs, within the long wave pattern. can indicate a possible game changer. I just don't see why this should be the case for the reason I've already stated. I should add that it's around this time period that the upper air is changing from a positively tilted trough mid Atlantic to the aforementioned height rises. The det, runs may well struggle.

Sorry for brief response Knocker, was putting kids to bed. Yes, i was referring to op runs. On yesterday's 00z the Atlantic low train hinders the northwards progress of the Azores High into the mid-Atlantic, preventing cooler air sinking south from Greenland. Now that may be a temporary delay but clearly a very different outcome from the 12z. But usually, a forced delay does affect things further down the line, even if just positioning.

Upper or surface air? Well, I rarely see one working without the other - here, a small upper trough accompanied the extra Atlantic low - which promoted a rise in pressure ahead of it.

Anyway, onto today. Ignoring temperature, the latter stages of GFS is a holy grail run for many northern sun lovers away from Western coasts, with a UK high at last for a few days. It manages a decent Saturday away from NW areas, as high pressure rises ahead of a rather menacing low for Sunday which goes through the north, probably affecting the south too. But beware - the UKMO keeps a flat pattern out till T144, which is changeable for all.

Edited July 31, 2016 by Man With Beard

[knocker]

Morning MWB

Looking at the GEFs this morning you can see where it's coming from. At t204 it has the transition to height rises in the western Atlantic but also a negatively tilted trough into Scandinavia, This will allow surfaceridging from the Azores. It then moves everything east so portending  longer influence from the surface HP vis the Azores.This is not the scenario, at least in that time frame, from last night EPS so it will be interesting to see this mornings. After this hiatus it then proceeds to flatten out the flow and bring us back to where we were.

[Frosty.]

The GEFS 00z mean indicates the Azores high / ridge will build in across the uk from next weekend onwards with increasingly warm and settled weather across England and Wales which may extend into northern uk too, temps rising comfortably into the mid 20s celsius range across southern uk..this is not deep Fi, just a week away...even spock is mildly impressed!

[knocker]

The ecm also shunts the upper trough east by the end of the run with the HP building mid Atlantic. I've absolutely no idea what to make of the cut off upper low but it's introducing some WAA from Europe into the equation

Edited July 31, 2016 by knocker

[Cloud 10]

Severe gales at day 8? Surely the ECM 00z is 'avin a larf'

 

[Frosty.]

You can see why the GEFS 00z mean looks so good this morning at T+240,, there are some cracking perturbations with several of them showing intensifying anticyclones centred over the uk by day 10 or a little sooner..great charts for a sunday, or any other day for that matter!

[markyo]

13 minutes ago, Karl. said:

You can see why the GEFS 00z mean looks so good this morning at T+240,, there are some cracking perturbations with several of them showing intensifying anticyclones centred over the uk by day 10 or a little sooner..great charts for a sunday, or any other day for that matter!

We will see Mr Positive,got a feeling 24hrs time these charts may have shall we say altered a tad!

[Frosty.]

Well markyo I'm only showing what the charts are showing and it looks good to me, the Gem 00z is a massive upgrade on yesterday's 00z in terms of warm anticyclonic weather from next weekend onwards with temps well into the 20's celsius.

[mb018538]

Strange output today....ukmo not playing ball at all though. Until I see some universal agreement I shall remain very cautious!

[Singularity]

Fascinating model runs this morning, enough to trigger a rare comment on here from me.

That hybrid-looking system in the N. Atlantic in 6-7 days really lets the cat out of the bag; there is a big transport of subtropical air across the UK and NW Europe, with subsequent pattern amplification that should lead to a strong Atlantic ridge developing, the subsequent movement of which will depend on the orientation of the NW flank of the warm air region - it will guide the behaviour of the jet stream. What movement we see is anyone's guess.

Of course this all means that uncertainty has shot through the roof. I mean - who's to say that intense area of low pressure even develops? This morning's GFS/ECM agreement with respect to that storm is the first instance of such, which undermines confidence in the outlook.

[markyo]

18 minutes ago, Karl. said:

Well markyo I'm only showing what the charts are showing and it looks good to me, the Gem 00z is a massive upgrade on yesterday's 00z in terms of warm anticyclonic weather from next weekend onwards with temps well into the 20's celsius.

Yep agree,just need those other models to come onboard especially Meto,if these remain generally the same in the next 24hr then your on to something but as we all know thats a long time in model watching! 

[Frosty.]

I'm cautiously optimistic this morning, the Gfs / Gem / Gefs 00z all show an increasingly warm anticyclonic outlook from next weekend or shortly after. If they were showing cool and unsettled I would say so..but they're NOT!

[Nouska]

1 hour ago, Singularity said:

Fascinating model runs this morning, enough to trigger a rare comment on here from me.

That hybrid-looking system in the N. Atlantic in 6-7 days really lets the cat out of the bag; there is a big transport of subtropical air across the UK and NW Europe, with subsequent pattern amplification that should lead to a strong Atlantic ridge developing, the subsequent movement of which will depend on the orientation of the NW flank of the warm air region - it will guide the behaviour of the jet stream. What movement we see is anyone's guess.

Of course this all means that uncertainty has shot through the roof. I mean - who's to say that intense area of low pressure even develops? This morning's GFS/ECM agreement with respect to that storm is the first instance of such, which undermines confidence in the outlook.

You'll be doing some head scratching in the next few days and beyond.

UKMO were first to suggest this sub-tropical hybrid forming from a piece of vorticity leaving the Carolina coast and merging with low heights in the Atlantic. The fact they are all showing a form of this now may be stronger possibility. Just shows why longer range output is no guidance at this point of the year.

Talking of curve balls - the FIM will be raising a few eyebrows.

56 minutes ago, Snowy L said:

Anyone else think the 2m temperaures are a bit off in FI? You would think upper temperatures of 15c+ in Southern England would bring more than a maximum of 21C.

 

 

Edit: In fact the area under 15c upper air doesn't even reach 20c.

One of those occasions where theta E charts tell a better story.

 

Edited July 31, 2016 by Nouska

[markyo]

40 minutes ago, Karl. said:

I'm cautiously optimistic this morning, the Gfs / Gem / Gefs 00z all show an increasingly warm anticyclonic outlook from next weekend or shortly after. If they were showing cool and unsettled I would say so..but they're NOT!

Wasn't having a go! Just it's so unpredictable at the moment to be honest any out come could evolve,stand by my 24hr though, We will see,very interesting watching to say the least.

[Snowy L]

Anyone else think the 2m temperaures are a bit off in FI? You would think upper temperatures of 15c+ in Southern England would bring more than a maximum of 21C.

 

Edit: In fact the area under 15c upper air doesn't even reach 20c.

Edited July 31, 2016 by Snowy L

[Frosty.]

4 minutes ago, markyo said:

Wasn't having a go! 

I know, sorry if it came over that way

I agree with you, nothing is in the bag or set in stone etc but I'm cautiously optimistic that at least southern uk could be in for a nice and warm spell by the end of the week onwards.

[Man With Beard]

GFS 06Z - best run of the summer? Very good for the south from 5th August a good week, and the north joins in by the 8th too

[damianslaw]

A changeable week ahead - atlantic trough gaining the upper hand and quite cool for what is on average our most warmest period of the year. Models are showing a change come next weekend, with an amplified flow taking place, allowing some warm air advection through the eastern atlantic thanks to a deepening low pressure tracking out of the USA, thus the result is for the azore high to ridge northwards stabilising things somewhat, southern parts at least could be in for a very decent weekend, whereas the north may take another glancing blow from trough action to the NW, before perhaps also reaping the benefits of the ridge in a more pronounced form as we enter the second week of August. So encouraging signals from the models today, that we may be about to see a much more settled warm summery spell from next weekend onwards. How long such a spell may last is the question..., the theme of the summer so far has been for any such spells to be quickly diluted, as renewed energy in the jetstream forces down on the ridge quickly collapsing heights and sending us back into an atlantic driven pattern. This is the most likely scenario in terms of probability, but the outcome will be determined by the strength of any ridging, its position of central heights, and more importantly the strength and track of the jetstream. At this juncture best not to raise hopes up too much (as is always the case in the country), but I'm mildly confident of a few very fine days indeed for southern parts at least from around the 6-10 August.

[Frosty.]

Well if we had a  spell as good as the Gfs 6z op run from Friday onwards I wouldn't care if T+384 looked a bit unsettled. I think most of us would like a warm anticyclonic spell as this run shows. The week ahead is going to bring rain and showers, warm sunshine too and welcome rain to the south where it's been dry in places for a while but hopefully we are then on course for a welcome break from this generally changeable / unsettled summer. This isn't a fluke run, the gfs 00z showed it, the gefs 00z perturbations did too and the Gem 00z.. it would be just what this summer needs at this point!

[knocker]

This morning's EPS continues to develop mid Atlantic heights towards the end of the 10 day period with the trough to the north/north east thus veering the upper flow NW for a time bringing some unsettled weather to the north with drier and warmer interludes further south although overall temps around average or a little below. In the ext period the northward movement of Azores HP declines resulting in the general flow backing to the westerly quadrant so more of a N/S split with the Atlantic systems tending to track NE leaving the south basking in the warm interludes although still the temps around average in general but moving above and below latitudinally.

Edited July 31, 2016 by phil nw.
removed off topic remark.

[phil nw.]

Looking at the 06z ens stamps show signs of the Azores high moving towards the UK from around day 7/10

 http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=192

but again this looks like the pattern re-jigging with the ens showing it retreating after 3 or 4 days with the westerlies picking up again.Still looking quite dry after the next few days to the end of the run though, especially for the south with the main effect of the Atlantic fronts to the north west. 

A look at the London ens show an uptick in rainfall in the coming days before drying out again to the end.The surface temperatures again no great shakes around or just below average..

It will feel pleasant enough though in the sunshine.

 

Edited July 31, 2016 by phil nw.

[Frosty.]

1 hour ago, knocker said:

This morning's EPS continues to develop mid Atlantic heights towards the end of the 10 day period with the trough to the north/north east thus veering the upper flow NW for a time bringing some unsettled weather to the north with drier and warmer interludes further south although overall temps around average or a little below. In the ext period the northward movement of Azores HP declines resulting in the general flow backing to the westerly quadrant so more of a N/S split with the Atlantic systems tending to track NE leaving the south basking in the warm interludes although still the temps around average in general but moving above and below latitudinally.

 

Hi knocker (Malcolm)

I don't think anyone is saying its going to happen but there is nothing wrong with discussing the possibility of our first proper anticyclonic spell of the summer since it really does have support from the Gem and gfs ops / gefs mean especially so far today..another two or three days of similar charts I think the confidence levels will rise and who knows, even the EPS may improve too..

Edited July 31, 2016 by phil nw.
removed off topic comment in the quoted post.

[Methuselah]

Hey, Malcolm & karl...I see no mutual exclusivity between your respective prognoses; indeed, it's thanks to you guys (along with many others, of course) that I've been able to make fairly accurate medium-range forecasts to my family. (Barring one or two monumental howlers)

But that's the very nature of the UK's weather, isn't it: if one predicts an 'average' summer (or winter) one will be correct-ish 95% of the time? But, day-to-day details 10+-days' out...Forget it?

[Frosty.]

4 minutes ago, Ed Stone said:

But that's the very nature of the UK's weather, isn't it: if one predicts an 'average' summer (or winter) one will be correct-ish 95% of the time? But, day-to-day details 10+-days' out...Forget it?

Spot on Ed...I mean pete

[Frosty.]

The Gfs 6z op run was not alone with its warm settled extended outlook, the GEFS 6z mean looks good again and there are some peachy perturbations..if the charts look as good by midweek I think we can breathe a sigh of relief and look forward to our most anticyclonic spell of the summer so far. If not, at least it won't be for the lack of trying to get this summer to take off!

Edited July 31, 2016 by Karl.