Model output discussion 14/04/18

[ANYWEATHER]

To be honest folks no model agreement in the next ten days cool and wet gfs  warm and wet ecm we shall see

[Fourty Point Three Degrees]

ECM is barmy hot but I think its OTT at moment so I will refrain from posting any smiley emotioncons until all three main models reach an agreement and im seeing this heat within 72 range and not 144.  How many times do we see plumes and major heat get watered down until its a non-event? I think reality is needed - next week is still FI.  

[mb018538]

9 minutes ago, 38.5*C said:

ECM is barmy hot but I think its OTT at moment so I will refrain from posting any smiley emotioncons until all three main models reach an agreement and im seeing this heat within 72 range and not 144.  How many times do we see plumes and major heat get watered down until its a non-event? I think reality is needed - next week is still FI.  

Well 2 days ago we were faced with the very real possibility of the trough being slap bang over the UK! This is getting very close to the reliable, I’d say if it’s still there by the 12z runs tomorrow we will have sat/sun/mon at 96-144, and you’d think it’ll be fairly certain. The trough as a complication from ex-Chris has been resolved, so  fairly confident.

[damianslaw]

There are two forcing features so to speak at play as we move through the latter part of July, one is the persistant high to our NE, but the other is the atlantic which is forcing down on the azores high and will cause it to retreat away from the UK. The question is whether we see enough depth in warm uppers from the continent build NE through SE parts to fend off the atlantic, but in turn quite likely allow a heat low of sorts to develop to our SW, or we see a bit of a stand off and a slack pressure pattern take hold with instability thanks to the hot air.

My reckoning is the slack pressure pattern, not the extreme heat some are talking about, but a humid airstream - and a sneaky trough then finding its way into western shores with a slow breakdown - a bit like has just occurred.

[Cheshire Freeze]

Just now, damianslaw said:

There are two forcing features so to speak at play as we move through the latter part of July, one is the persistant high to our NE, but the other is the atlantic which is forcing down on the azores high and will cause it to retreat away from the UK. The question is whether we see enough depth in warm uppers from the continent build NE through SE parts to fend off the atlantic, but in turn quite likely allow a heat low of sorts to develop to our SW, or we see a bit of a stand off and a slack pressure pattern take hold with instability thanks to the hot air.

My reckoning is the slack pressure pattern, not the extreme heat some are talking about, but a humid airstream - and a sneaky trough then finding its way into western shores with a slow breakdown - a bit like has just occurred.

Completely agree. You've hit the nail I think. Humidity looks to be the key.

Very noticeable is the lack of 1030+mb heights that we were initially seeing, replaced by, as you say, something slacker. 

[Frosty.]

A very pleasing Ecm 12z ensemble mean hot on the heels of that fantastic operational earlier this evening!!☺

[chrisbell-nottheweatherman]

6 minutes ago, damianslaw said:

There are two forcing features so to speak at play as we move through the latter part of July, one is the persistant high to our NE, but the other is the atlantic which is forcing down on the azores high and will cause it to retreat away from the UK. The question is whether we see enough depth in warm uppers from the continent build NE through SE parts to fend off the atlantic, but in turn quite likely allow a heat low of sorts to develop to our SW, or we see a bit of a stand off and a slack pressure pattern take hold with instability thanks to the hot air.

My reckoning is the slack pressure pattern, not the extreme heat some are talking about, but a humid airstream - and a sneaky trough then finding its way into western shores with a slow breakdown - a bit like has just occurred.

Might I be allowed to enquire as to whether this might at least allow some thundery precipitation?

[January Snowstorm]

I must be missing something 

What I see is high pressure way out in Atlantic extending and keeping a slight ridge over us. A mix of sunshine and cloud and primarily because it's mid Summer temps remain quite good.

Surely awesome would be a high parked over us with a light easterly flow off the continent.

Of course things could be a lot worse just trying to establish the realism that whilst it's not a full on breakdown nor is it glorious sunshine

[tight isobar]

Out @144 via gfs 18z-suite..

And Rmm/ecmf..orb-mjo..

Sitting in western pac..actions...

Equalling, a decent yet building evolution.

Again the ens-supportings..are imo..on a catch up phase against there suites(cross)..

Its quickly tightening' into a locked phase of ridging into the nw-euro quaters.

=summer non let go....

And as b4-the depth of heat syphon...perhaps with it oil burner to be yet FURTHER -turned up!!!

 

I can see a clear 35c off plume influence within-5/7 day period...favoured southern drops.

Edited July 16, 2018 by tight isobar

[Captain Shortwave]

Day 6 charts

UKMO/GFS

   

The UKMO gets the ridge fully across the UK, the GFS seems to have a more organised area of low heights to our north which pushes down on the ridge somewhat though for many the weather is fine and very warm and thisrun does seem to have a little more amplification so more of a ridge might appear later on to our east.

Edited July 17, 2018 by Captain Shortwave

[bluearmy]

Fwiw, latest ec46 maintains generally settled conditions throughout August. Temps stay above average. Lower than average affecting w and s Iberia and se Europe which is also wetter than average. Scandi stays warm and dry. Obviously this is averaged out mean data. The uk prone to troughs trying to edge in from the west from time to time as would be expected. No sign on this model of any deviation from what the telecons have been signaling.  No surprise UU have brought in a hosepipe ban from the fifth - perhaps they were waiting for this latest run for final guidance. 

[Chesil View]

8 hours ago, Frosty. said:

A very pleasing Ecm 12z ensemble mean hot on the heels of that fantastic operational earlier this evening!!☺

Indeed so Frosty. Here at Broadmayne I have had just half a millimetre of rain in the last 47 days and looking like more of the same.  On course at my station for the driest June/July on record (including 1976)

[shaky]

Wow ukmo seems even more hot and humid on this 00z run that last nights run!!seems defo more humid and hot for friday and saturday than what was showing before but thats mainly thannks to a shortwave cutting through the west of the uk end ending up near biscay!!though yesterday it showed that same shortwave going north east towards norway!!hmm doesnt give you much confidence in the ouput especially when gfs is different at the same time!!still looking hot on both runs though and rainfall pretty much non existent!!!

[bluearmy]

No words needed .......

[Stevetynant]

19 minutes ago, bluearmy said:

No words needed .......

But some words would be much appreciated by those of us still trying our best to understand - thanks :0)

[mb018538]

31 minutes ago, Stevetynant said:

But some words would be much appreciated by those of us still trying our best to understand - thanks :0)

They are 500mb anomaly charts - with the colours representing spread of outcomes. Purples indicate good clustering and more certainty, sliding up the scale at the bottom to more uncertainty. It basically shows good probability of the UK being warm/hot and settled at 384.

[mb018538]

00z runs look good - ecm developing something of a nw/se split, with the hot stuff tending to be further towards the s/se. This ties in with the met update too. July going out like it started - flaming hot!

[Nick F]

2 hours ago, mb018538 said:

00z runs look good - ecm developing something of a nw/se split, with the hot stuff tending to be further towards the s/se. This ties in with the met update too. July going out like it started - flaming hot!

It does look that way on the 00z GFS as well, the model has high 20s to 30C across SE England and E Anglia everyday next week, cooler further north and west, but still pleasantly warm or very warm, I suspect it will be quite humid generally too earlier in the week, away from the far north, with the flow from the southwest. Any rainfall likely to be confined to northern and western areas, as Atlantic frontal systems try to make inroads but fail to make it the to southeast. without weakening considerably

Looking at the pattern, the general theme is for surface ridging extending from the Azores to be pretty much entrenched across the south over the coming 7-10 days, though upper troughs do look to pass through from the west or northwest time to time, weakening as they do coming up against underlying blocking, one does exactly that later this week, having little impact at the surface across the south, though bringing some rain to Scotland and perhaps far north of England late Thursday into early Friday. Then another upper trough moves in early to middle of next week, though divergence between GFS, which wants to disrupt it over UK and ECM which wants to keep it intact with little influence as ridging holds firm here.

There may not be right synoptics to get temps to the mid-30s or more next week, need trough to stay to the west and ridge to build to the east dragging a heat dome north for that, but ridging does look to persist across the south through next week, ensuring little relief for parched earth, any attempts by the models to introduce rain across the south appear to be thwarted as we approach closer in time to when it shows the potential for rainfall. Can see little signs of any real shift in patterns for now to end the drought.

Edited July 17, 2018 by Nick F

[Singularity]

The Atlantic trough just needs to be a bit sharper than the 00z GFS and ECM runs have gone with; that should  bring an end to the development of a vague 'col' to our near-NE into which shallow lows can keep on drifting and messing with the attempts to build a UK-Scandinavia ridge.

Recently, the MJO has been outperforming the model projections in terms of strength and propagation rate and there are signs it will continue to do so for at least a little longer, so that ought to help get that extra sharpness to the trough into place. As far as I can deduce, that's part of what tight isobar was referring to late yesterday morning.

 

First half of summer, we became used to patterns that the models can resolve relatively easily as it was just a case of extending the general pattern forward.

Now, the models are seeking to resolve the manner in which a whole new pattern manifests at the expense of the old one. They always struggle with that, and often until frustratingly late notice.

[shaky]

Hmmm gfs 06z seems to have gone trough crazy after 200 hours on the 06z run!!surely wont be that low pressure dominated will it!!

[Man With Beard]

It's looking like yesterday morning's ECM ensembles were a bit of a one off; the outlook remains warm with tendencies to a NE ridge and a southerly influence on the UK, but the extreme plumes of yesterday have shrunk back.

D11 on the clusters now looks like rather more of a fight being put up by the Atlantic trough, though still potential for a plume and only the control run cluster doesn't look predominately warm/hot

By D15, the battle between Atlantic trough / Scandi ridge is still going on, but not really clear where the battle lines will be drawn. Further west, hot for the UK, further east, we could be stuck under the trough. Hey, haven't I heard that once or twice recently?

But with troughing consistently getting downgraded as T0 approaches this summer, you have to feel the ridge is still in a good position to win out even as August approaches.

 

[Nick F]

11 minutes ago, shaky said:

Hmmm gfs 06z seems to have gone trough crazy after 200 hours on the 06z run!!surely wont be that low pressure dominated will it!!

Yep, seems keen, again, to rush in unsettled Atlantic westerlies. But, as we've seen before over recent few weeks when it's tried to breakdown the drought and heat, it hasn't been correct. It will happen, but I'm not holding my breath for next week at least. Would think the Atlantic trough trying to bring the breakdown it shows is more likely to disrupt to the west and southwest, as they have done before, because of blocking close to the east and NE being underestimated.

[Frosty.]

I notice the words very hot are in the latest update from exeter which is why I'm showing these charts from the GEFS 6z..it could well be that the hottest weather this summer is still to come!

 

[mb018538]

Ignore the 6z op as well, cold outlier....rest of the ensemble mean matches the ecm and ukmo take on things. Heat wave part 26 due to start in a few days!

[Tamara]

On ‎08‎/‎07‎/‎2018 at 18:21, Tamara said:

That suggested surge in atmospheric angular momentum tendency is duly underway. (Also notice when the last comparable leap occurred in mid April which presaged the first (of the many to come) warm downstream ridges of the season).

 

Its equally good to see NWP models trying to solve the puzzle heading in week 2 of a trough replacing a long lasting ridge in the Atlantic and balancing the equation of how much downstream ridging occurs ahead of the trough. There are going to be mistakes for sure with this one and worth taking both operational and ensembles (inc clusters) with a bit of a pinch of salt for a while.

Whatever transitional flurry of more changeable conditions may come out of this, there is another lovely week (at leas ) to come and its seems unlikely our re-adjusting ridging is to be heading too far away. Also reasonable to suggest that jet stream distribution in the very extended period increasingly favours instability to focus to the SW (too much progressive push will probably be indicated to push eastward) and * just possibly* the hottest phase of this wonderful summer yet to come as a south easterly vector comes into play during the last third of July>into August

We will watch and see how it unfolds anyway.

Keep enjoying it

 

Keep enjoying it

Sure enough, if we ignore the distractions of intra day NWP output that detracts from the bigger picture, the suggested trend evolution has come forward as suggested a week back. Hence heights over Scandinavia are shaping up as an increasingly dominant pattern feature in the further outlook at the same time as the models keep working out how to resolve the energy equation of troughs bumping up against what equates to an oven door.

Mid July has long been inked in my own little diary as crossroads time in terms of angular momentum vs seasonal wavelength changes as to whether the amazing summer sustains - or whether it diminishes into something significantly cooler and more unsettled (at least relative to the ultra high benchmark of the summer so far).

The diagnostic tests available c/o of the Global Synoptic Dynamical model (GSDM) that can be applied to NWP credentials continue to prove their value to picking out the historically known fallibilities of numerical models.  The Global Wind Oscillation, which in simple terms is a plot depiction of jet stream global wind-flow strength and trajectory, is as expected reflecting the recent surge in atmospheric angular momentum tendency with a swerving orbit out into quite a high amplitude Phase 4. 

"Great"! ...many will  chorus together  But what does all this mean in terms of the synoptic interpretation moving forward?

 GWO Phase 4 is reflective of rising AAM as characterised by the addition of westerly winds into the tropics which propagates rossby wave dispersal to the extra tropics -  amplifying the jet stream, downstream, and consequently sustaining anomalous mid latitude ridging at a time when those seasonal wavelength changes would have seen the pattern flatten out more successfully otherwise at this time. Much as some modelling has tried to do over recent days until realising (and as stated likely in an earlier post) that something rather different is going on - and as a consequence pressure remains more stable instead. 

This explains why the col that keeps seeming destined to be filled by a trough, doesn't end up verifying (the trough)

The extended ensembles might ebb and flow with the suggested added heat equation, and very probably will continue to do so - but the evolution to instability piling up to the SW and forcing some considerably further enhanced heat domes to advect northwards ahead of it to intensify the inferno feel is not any hyperbolic exaggeration and has conceivability attached to it through late July and into the new month. How much hotter and how far north that upgraded heat advects remains to be seen - but the GSDM jives with the model number crunching in respect of the possibilities