Model output discussion 14/04/18

[Frosty.]

Mmm looking more settled than I was thinking yesterday...really superb 00z output showing this summery spell extending well into June and potential for hot weather..flaming June anyone?

[Frosty.]

The Ecm 00z operational really cranked up the continental heat and the mean is looking really good as well

[Guest]

On ‎28‎/‎05‎/‎2018 at 20:42, Alderc said:

The problem is posting charts without an explanation is that it just doesnt present the full picture, some of those ECM charts for Wed/Thurs look great on the surface how add in some of the other details and reality is quite a bit different. With a moist flow over the north sea both Wednesday and Thursday will see a lot of cloud that will be very stubborn to move away from all but the west and maybe part of Wales and the south coast, a number of places likely to stay in low double digits where that cloud persists.

Remember those summary charts being posted from Monday for the middle of this week, just shows how the actual conditions can be hugely different what on the face of it appears to be favourable synoptics. Two days ago temps were progged to reach low twenties across most locations however its actually turning in a cool May day (max 15C so far here). My fear is with the current output there could be a number of days such as we seeing today.

[Frosty.]

1 hour ago, Alderc said:

Remember those summary charts being posted from Monday for the middle of this week, just shows how the actual conditions can be hugely different what on the face of it appears to be favourable synoptics. Two days ago temps were progged to reach low twenties across most locations however its actually turning in a cool May day (max 15C so far here). My fear is with the current output there could be a number of days such as we seeing today.

Yes today is abysmal, cool and cloudy with a few showery bursts of rain even though we have an Ecm chart like this!!..later on today it should become warmer and sunnier across parts of southern England and then apparently tomorrow should be much warmer across the board with sunny spells but with an increasing risk of severe thunderstorms and local flash flooding spreading from the south.

Looking towards later this week / weekend it's set to become drier across most of england and wales with warm sunny conditions with the risk of heavy showers /  thunderstorms being further north across n.ireland and scotland.

Edited May 30, 2018 by Frosty.

[Guest]

8 minutes ago, Frosty. said:

Yes today is abysmal, cool and cloudy with a few showery bursts of rain even though we have an Ecm chart like this!!..later on today it should become warmer and sunnier across parts of southern England and then apparently tomorrow should be much warmer across the board with sunny spells but with an increasing risk of severe thunderstorms and local flash flooding spreading from the south.

Looking towards later this week / weekend it looks like becoming drier across most of england and wales with warm sunny conditions with the risk of heavy showers /  thunderstorms being further north across n.ireland and scotland.

Under clear skies and a light winds you'd expect temperatures to be close to 30C in the South East and widely 24-27C

[Frosty.]

On 28/05/2018 at 20:42, Alderc said:

The problem is posting charts without an explanation is that it just doesnt present the full picture, some of those ECM charts for Wed/Thurs look great on the surface 

You were right about today, gorgeous looking charts at face value don't necessarily mean gorgeous weather as today has proved across most of england and wales although it is quite a pleasant day across most of scotland & n.ireland with warm sunny spells.

[Guest]

10 minutes ago, Frosty. said:

You were right about today, gorgeous looking charts at face value don't necessarily mean gorgeous weather as today has proved across most of england and wales although it is quite a pleasant day across most of scotland & n.ireland with warm sunny spells.

Yes the north west has faired very well today and especially yesterday, which is not uncommon in May.

Clearance coming into Kent now, too late really for many but a chance somewhere in Kent could jump to 22-24C with some high DP's as well.  

Interesting that GFS 06Z goes high 20's again in the south east as early as Monday again. Importantly (for those who work) the weekend is shaping to pretty warm and sunny again. In the last 6 weeks of so we have had as many fabulous weekends (if not more) than many of the entire summers from 2007-2012 produced. Long may it continue

[Tamara]

On ‎21‎/‎05‎/‎2018 at 14:18, Tamara said:

what is very important as we hit June is that we see clear signals that MJO forcing wants to embrace eastward shift to the Pacific as represented by an evolution to Phases 6,7 and 8.

This, as demonstration that the upcoming cycle represents a further move away from La Nina with accelerating westerly wind inertia in the atmospheric circulation sustaining the priming of downstream summer warm ridges rather than sustained lapse into downstream summer chilly trough.

The deterministic tropical convection forecasts have been proving, not unusually, a bit too progressive with trying to break down amplitude of the latest cycle.

 

There is a conceivable chance this time around that modelling may overcook -ve AAM downside, and hence any blocking in the North Atlantic and/or Greenland may be overblown.

...and so it has been proving to be the case

Extended NWP attempted suggestions of retrogression of the pattern have been adjusting continually backwards over the last 10 days as updated atmospheric angular momentum tendency plots have kept showing a steady upward trending.  As a result, the increasingly warm European pattern has been steadily extending in longevity

Stripping away the longer term -ve AAM biases, then adjusted model plots show a continuation of this buoyant trend through , at the least, the opening 10 days of June

 

The continued active periodicity (recurrence cycle) of tropical convection of several months has confirmed suspicions that deterministic MJO models would persist in undercooking eastward progression and amplitude of progression of tropical thunderstorm activity, and their associated westerly wind bursts that drive the rossby wave trains that develop downstream amplification and carve out anticyclones -  and hence overestimate downside of AAM tendency. Anything beyond 4/5 days on these plots is subject to work in progress - amplitude has been continually revised upwards through this present cycle

 

Hence the work in progress adjustments that have percolated into NWP to keep the downstream ridging stronger for longer, and put back the retrogression of the pattern and suppression southwards of the Jetstream.

Taking into account these atmospheric circulation trends, then the evolution of the cycle in June, is closely related to the seasonal wavelength changes into summer, and will continue to be tied into an active tropics to keeping a warm pattern sustained.

Of course, the cycle wanes as well as waxes, so at some stage there will be a backward adjustment (probably tied into the latter stages of the current tropical cycle once it has arrived in the Pacific) but what will be important if/when any less warm and settled interlude arrives will be the measure of how much higher the next lull phase in the tropics and extra tropics is compared to earlier in May.

So, for once, we are coming into early summer with the atmospheric cycle pre-disposed towards downstream summer ridges - rather than seeing momentum collapse as it has done in years like 2007 and 2011.

There is little point, in my opinion, of over dwelling on the winners and losers of a start of season pattern that is bound to have lag restrictions hung over from an extended cold season up to mid April at least. This is an island, and nothing is going to change that. Relatively cold seas are bound to make differences and cause issues such as low cloud and mist particularly on windward coasts, and especially added on to the detritus from thunderstorm activity from a nearby continent that is, self evidently, land-locked and therefore subject to much more rapid diurnal heating sooner that the UK

This is as good a start as any could realistically hope for and every chance that future warm spells might build on the intensity of the current ones. Upper cold pooling to our west and south west and heat ridging in all vectors to our east is the broad-scale pattern that our best summers are built on and can be very sustained.

 

[Singularity]

Many thanks as always Tamara for your extensive insight .

Funnily enough I was just now having a gander at the MJO phase 4 composite for June having noted the decent amplification now looking to be retained through that as we change months;

 

This is much improved from that of May (Scandinavian troughs and ridges W/NW of the UK) and lends good support to those model runs which prevent the Atlantic trough from powering its way over the Scandinavian ridge any time soon. So the 06z GFS seems too progressive in that respect.

So what of phase 5 if we see that to follow?

It looks very interesting, but has low reliability, so not worth putting too much weight on that one. 

The broad notion of propagation into Pacific = very helpful for achieving fine summer weather across the UK in general (allowing for local variations) is the one to keep in mind until further notice .

[Summer Sun]

Looking at 12Z UKMO high pressure will build over the UK again as we go into next week

[Matthew.]

3 minutes ago, Summer Sun said:

Looking at 12Z UKMO high pressure will build over the UK again as we go into next week

Looks like a northeast drift again does look a lot slacker though so hopefully not feeding in enormous amounts of low cloud

[I remember Atlantic 252]

Yes Matthew, was about to post YUK to UKMO 120 chart, could be 14C max here mon and tues bleeurgh

[cheese]

14 minutes ago, Matthew. said:

Looks like a northeast drift again does look a lot slacker though so hopefully not feeding in enormous amounts of low cloud

This north east wind is such a nuisance - we're the only place in Europe getting plagued by low cloud.

[I remember Atlantic 252]

138 on GFS, looks yucky, sea mist written all over it, sigh again, 27C W Scotland, 14C here

[Frosty.]

6 minutes ago, cheese said:

This north east wind is such a nuisance - we're the only place in Europe getting plagued by low cloud.

Anyone would think it's a poor spell of weather reading your post but for most of the uk with the exception of the occasional disappointing day, today for example..it's been a generally fantastic late spring with well above average temperatures, some amazing thunderstorms and lots of very warm sunshine and looking at the models, there's plenty more to come!

  

[cheese]

1 minute ago, Frosty. said:

Anyone would think it's a poor spell of weather reading your post but for most of the uk with the exception of the occasional disappointing day, today for example..it's been a generally fantastic late spring with well above average temperatures, some amazing thunderstorms and lots of very warm sunshine and looking at the models, there's plenty more to come!

  

It's been crap for the past 2 days here and the rest of the week looks the same I'm afraid. Nothing to celebrate.

[Matthew.]

The first chart from June 1995 shows a similar problem for the east although it is a very slack northeast drift. The second is where the money was in August. Sea hart is different to low cloud in my view. Sea harr burns back to within a mile of the coast in no time. What we’ve experienced the last week is completely different with cloud amounts

Edited May 30, 2018 by Matthew.

[Frosty.]

1 minute ago, cheese said:

It's been crap for the past 2 days here and the rest of the week looks the same I'm afraid. Nothing to celebrate.

Go in the moaning or regional thread then! Imby posts really annoy me because this thread is about what the models are showing generally across the uk!

[Polar Maritime]

And back to what the models are showing please, As frosty says let's please use the moaning or regionals, You can even ramp moans in there.. 

Thanks 

 

Edited May 30, 2018 by Polar Maritime

[northwestsnow]

Absolutely fabulous 12z output for warm weather fans with the azores high dominating preceedings.

Yes there will be exceptions to the rule with some places faring bettef than others but just look at ukmo tonight.. superb.

[I remember Atlantic 252]

Just now, northwestsnow said:

Absolutely fabulous 12z output for warm weather fans with the azores high dominating preceedings.

Yes there will be exceptions to the rule with some places faring bettef than others but just look at ukmo tonight.. superb.

agree fully for your area! Sat/Sun look best for mine, E'ly temporarily cut off

[Mike Poole]

Just considering the long range models as we head into summer, first thing to note is that the Met Office contingency planners forecast, of which the May update is effectively the summer forecast, closely follows the raw GloSea5 output from earlier in the month, giving a 40% probability of the warmest quintile over the 3 month period, higher probability of drier than average too.  Full forecast here for temperature and precipitation, heavily caveated of course given it's probably the best  outlook since the infamous 2009 seasonal forecast.

https://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/forecast-temp-jja-v1.pdf

https://www.metoffice.gov.uk/binaries/content/assets/mohippo/pdf/public-sector/forecast-precip-jja-v1.pdf

One thing they mention is cooler than average North Atlantic sea temperatures to the west of the UK, looks farther west than that cold pool a couple of years ago (which if memory serves me some blamed for cooler summers), current sea temperature anomoly:

It's also noticeable how the sea around the UK has warmed given how cold it was in March.

They do say no clear signal for June though.  Here's yesterday's four CFS Z500 anomalies for June, still none too shabby, 18z first:

Edited May 30, 2018 by Mike Poole

[Mike Poole]

GEFS 12z mean looking promising to T204, next Friday, signal gets less clear thereafter.

ECM rolling out, and at T168, this really does look a good evolution with the high over Scandi, and the ridge from the Azores.  

Edit: double down on that with the T192:

Edited May 30, 2018 by Mike Poole

[Frosty.]

The devil will be in the surface detail but the Ecm 12z is showing a very summery..start to summer..great charts!

Edited May 30, 2018 by Frosty.

[Matthew.]

Parts of Norway/Sweden warmer Spain at the moment as they’re experiencing northern blocking with a trough underneath