Model output discussion - summer rolls on

[Weather-history]

GFS 06z op run brings a real  beast of a plume

 

Edited July 22, 2018 by Weather-history

[Captain Shortwave]

The GFS doing the modern thing of compacted all of its hot outliers into one ridiculous low resolution run.

   

Because it is perfectly sensible for the 20C isotherm to reach Scotland!!!

Right back to more sensible discussion, again further ahead it looks like any breakdown from the west will struggle to fully cross the UK completely so it isn't unfeasible that southern and eastern areas will remain fine and at least very warm. So we will see a front try and cross the UK during Friday and likely we will see a more widespread fine weekend as a ridge builds across the UK behind this weeks main trough.

   

Beyond this, to be honest I can only see one outcome and as shown on the GFS (in an extreme manner), this outcome is another attempt to push heat northwards from Spain and France with the UK remaining on the boundary between the huge ridge over the continent and the Atlantic trough.

[MattStoke]

GFS once again showing the potential for further hot/very hot conditions further ahead. Even if we see a more settled and less hot blip late next week, which those in the south and east might not, and even if it is overdoing any potential plume.

Edited July 22, 2018 by MattStoke

[Leo97t]

If the 6z verifies the 40C barrier is being broken. Ensembles showing amazing agreement for a plume around 3rd/4th/5th August although I think the 6z is the absolute peak scenario 

[Djdazzle]

3 minutes ago, Leo97t said:

If the 6z verifies the 40C barrier is being broken. Ensembles showing amazing agreement for a plume around 3rd/4th/5th August although I think the 6z is the absolute peak scenario 

I agree but it’s  so far away at the moment. The models can’t even agree on the end of this week yet!

[Frosty.]

The Ecm 00z ensemble mean still looks progressive by day 10 with cooler atlantic air making inroads and the warmest / hottest air shunted away eastwards but the week ahead looks hot further s / e / se and may last longer than this mean suggests longer term.

[JBMWeatherForever]

I personally see the overall trend as we head towards August to be one for the heat over more southern and eastern parts of the UK to spread back to the rest of the British Isles. At the moment August looks to me like seeing a gradual strengthening of High pressure on the whole with more widespread heat as a result. The hottest part of summer I think is yet to come!

[TJS1998Tom]

Not only does the latest GFS shows impressive heat but looks like an impressive breakdown could follow, especially for the West. High Cape and heavy precip

[johnholmes]

1 hour ago, mushymanrob said:

feasible !

 

Yes, likely to occur ?, a prob 40% I would say at the moment

[Fourty Point Three Degrees]

Aug 03rd on GFS 06z reminds me of that very day in 1990 which saw the 37C Cheltenham record.  Nice to see ensembles showing more support for a heat wave as we head into Aug.  Fingers crossed this upgrades into a 7 day spell instead of a 2/3 day spell.

 

[SLEETY]

long way to go yet till we can be certain what's going to happen by the weekend,the low is going to cause major headache for the models as it interacts with the developing blocking high,fascinating watching how this will pan out.

[Singularity]

52 minutes ago, SLEETY said:

long way to go yet till we can be certain what's going to happen by the weekend,the low is going to cause major headache for the models as it interacts with the developing blocking high,fascinating watching how this will pan out.

Indeed - I’m still not ruling out an outcome that sees the trough far enough west and the secondary low moving in such a way that a ridge builds sufficiently strongly ahead of it to prevent so much hot air heading toward Norway and instead direct that across the UK.

Far from favoured by current modelling, but feasible based on similar historical events.

First week of August has the much higher chance. Odd to see so many EPS members freshening things up instead - but I’ve noticed ECM handling the current eastward propagating MJO very poorly (as usual - it’s worse than GFS when it comes to that!) which makes the difference between a more Nina-like trough movement close to the northwest of the UK (stalled MJO that ECM shows) and a Nino-like stall out west with a continental flow favoured for SE UK in particular (propagating MJO that’s instead being observed).

So unless the MJO suddenly falls in line with the ECM/EPS projections, they will soon be changing their tune toward something more like the GFS 06z of today or 18z of yesterday (for example) but with much variability in imported heat, of course.

Edited July 22, 2018 by Singularity
There’s always one latter... ;)

[mushymanrob]

2 hours ago, johnholmes said:

Yes, likely to occur ?, a prob 40% I would say at the moment

Ill take that % at that timeframe lol

Ok, im not expecting that to vetify in full, but something similar would be just as welcome . Im liking the potential though.

[Mike Poole]

So as we await the 12s, the GFS paralell 6z is reinforcing the idea of real heat around the 5th August, my money is still on this date being the hottest of 2018.

Records broken? Too soon to tell, but fascinating model watching.

Edit, the red beast is still nibbling at the UK at the end of the run what on earth is going on? 

Edited July 22, 2018 by Mike Poole

[Tamara]

@Singularity Yes, the usual caveats and cautionary words for deterministic MJO modelling - especially with this Pacific forcing

Which leads appropriately onto this:

Have been wondering for quite a while if this is where we are headed for the last third of the official summer in terms of overall pattern

 

I hesitate to use these composite charts as they need careful assessment of the whole tropical and extra tropical wind-flow spectrum before applying to any suggested evolution of pattern and should never be taken at complete face value - certainly in terms of attempting to translate them into surface pressure detail.

But this is consistent enough with transition years to El Nino starting from the Spring, and now showing the atmosphere starting to tentatively embrace a fledgling very weak Nino type of feedback for the first time in a long time...

 

..and more importantly than that, consistent with where angular momentum and tropical forcing are at this time as reflection of the base state changes that look to prevail the further official autumn approaches. Also seasonal wavelength changes, assuming relative angular momentum does not deviate too much below current levels in the natural tropical cycle (and this will need to be watched) will in my opinion guide the current evolving pattern in this general direction.

Furthermore plenty of seasonal modelling supports this type of evolution and its worth noting in this respect also the very extended METO forecast indications heading through August. Taking heed of my own cautionary advice with respect to the composite chart above - the depth of the trough anomaly into Europe should best be interpreted as heat lows with the focus being the main upper trough to the west increasingly taking on a more disrupted aspect to the south west at the same time as the ridging to our NE overspreads the trough somewhat. So a continental feel to the weather and perhaps more prone to thundery disruption within the huge heat field that has taken siege occupation of much of Europe.

I would like to see this as an acid test of some data, and as to be expected to be said by me, not a forecast  - as I do not try to attempt these.   But based on personal interpretation of the GSDM, in which a lot of kudo-faith is placed, and the way that NWP (ignoring the daily calf on roller-skates accident-prone type tendencies) is showing willing to stumble its way along this path as led most realistically by the upper modelling outlook forecasts, then it seems an intuitively fair suggestion to put out there.

I think its also reasonable as part of this thinking to add support to Mushy's feasibility equation of a main heat spike dome in the early part of August. At least to some degree.  If the trough pattern is to evolve, eventually, towards the SW as part of the above process, then its logical enough to assume that at least some of that greater heat (over and above the already existing very upwards adjusted levels of the summer so far) might be backed westwards - at least for a time.

The ECM has been appearing progressive currently, relatively, with the pattern up to day 10. But even within this snapshot of time (which is all it is) one cannot ignore the next acceleration of trend in early August which is immediately beyond this period - in that respect not too different from GFS. And, which also leads full circle to the start of the post and the likelihood that Pacific forcing is not done with so soon. These stats might be London based, but taking into consideration the rationale eschewed in the post, it might be the greatest chance for wider plume advection.

 

Its possible thereafter that a generally warm and humid regime prevails as the very greatest heat is mixed out and with scope for the drought to be alleviated to some degree as the heat more generally destabilises over larger areas within the evolving August regime. But that is filed away under pending based on how, precisely, the coming weeks play out.

Summer 18 as a season has some weeks left in it, and in terms of its prevailing highly seasonal weather type, has quite some way to go yet

 

 

[Mike Poole]

UKMO tonight puts the UK in a bit of a col, neither nowt or summat you  might say, here T144

let's see what the other models say!

[northwestsnow]

UKMO brings in uppers of 18 @850 into the SE during Friday.

Suggestive of temps into the low 30s?

[MattStoke]

Hot end to the working week from the UKMO. Where as the GFS shunts the heat away eastward.

[Djdazzle]

UKMO and GFS keep Friday very hot in the SE at least. Slight westward correction of the LP makes a big difference.

[Frosty.]

4 minutes ago, northwestsnow said:

UKMO brings in uppers of 18 @850 into the SE during Friday.

Suggestive of temps into the low 30s?

Indeed, some very hot weather for the E /SE on the ukmo 12z..sustained heat during the week ahead in the low 30's celsius range but even away from the hot zone it still looks very warm / feeling hot in the strong July sunshine away from the far w / nw.☺

[shaky]

Gfs has mid to high twenties widely throughout the week so still hot but not extreme!!ukmo on the other hand brings that plume back further west again and gets really hot across central.and eastern england on friday!!happy with both outputs to be fair!!

[Djdazzle]

1 minute ago, Frosty. said:

Indeed, some very hot weather for the E /SE on the ukmo 12z..sustained heat during the week ahead in the low 30's celsius range but even away from the hot zone it still looks very warm / feeling hot in the strong July sunshine away from the far w / nw.☺

Still think 35C is possible with those charts.

[Singularity]

Interesting - UKMO uses a weak low sliding by to our south to nudge the heat plume in a great deal more than GFS goes with on Friday. So much so that it still looks stalled across eastern parts on Sunday.

So it seems we don't actually have any clue about the details for Fri-Sat yet. So much for an overall move toward not as hot but drier  - though actually, it still does look drier than was the case a couple of days ago, as the Atlantic trough doesn't get so directly involved with proceedings. Maybe some heat-forced thunderstorms in the east, which would be intense but localised.

Pleased to see Tamara's input today, reassuring me that I'm thinking straight even when contemplating the UK being involved in the 'greater' heat over nearby Europe for a time in early August. Heat which can exceed the usual upper limits due to a number of countries to our SE, E and even NE now being in a state of widespread drought. I believe that, along with our own dryness of soil, is why GFS has been showing such high maximums on some runs lately (along with such high 850s across such a wide area in a few cases; such prolonged and intense heat builds up from the surface in a 'heat dome' formation).

[Decemberof2010]

And yet again up pops that date.... 3 August 

[Weather-history]

GFS 12z is a dry one for most of England and Wales, rainless in the SE to the start of August