Model Output Discussion 31/05/14 onwards.

[Captain Shortwave]

Waiting for all this to end in tears tbh. We're looking here at something towards the days 9 and 10 juncture (after the initial potential wet plume next weekend). We could just easily see troughing managing to snake through, ala GFS FI, as HP building sufficiently. It's a winter easterly scenario, summer equivalent.

Given that the GFS/ECM and GEM ens all say yes to drier and warmer weather in week 2 then I would say there is a good chance of that happening. Even the metoffice seem to suggesting longer drier spells of weather developing in the 6-15 day range. Which is certainly a move away from the changeable or even unsettled conditions which were bullishly put forward a couple of days back. 

 

As for next weekend, we need to see the continuing trend of the Atlantic trough sharpening up more quickly. by this I mean the trend for Thursday and Friday to be much drier than previously predicted as the East and South east of the UK becomes influenced by a weak ridge of high pressure building north/north east from Spain. This sharpening will (should might be the better word) correct the pressure pattern westwards though I don't know how far west we can pull it. The morning runs will show whether this is a possibility.

Edited June 1, 2014 by Captain shortwave

[Cheshire Freeze]

Personally i'm highly skeptical for anything more than 3 fine days and a thunderstorm. As John's chart shows, the high to our east is part of a larger set of high's over the Arctic. When i think of past glorious summer months, heights over the pole don't tend to be prominent and that's why i can see the pattern eventually collapsing.

This is pretty much EXACTLY how I interpret things too. Whilst you've got heights at high latitudes like that you'll struggle to maintain hot weather for the UK. Talk of 2003 and 2006 (as I read earlier) is quite frankly preposterous at this stage.All said and done, 3 fine days and a thunderstorm is typical British summer fayre....I'm sure most would take that though given recent summers. Edited June 1, 2014 by CreweCold

[bluearmy]

The ECM op was the hottest of the 50 members days 8 through 10.

[William of Walworth]

Not willing to try and call any details of next weekend, that of Sat 7th June, until about Wednesday. As many have said, current synoptic projections are ridiculously volatile --- future runs will surely chop and change this week..

 

On the hopecasting front though ..... <zips it>

[knocker]

The ECM ens is not quite as bullish as the ops, A knife edge still springs to mind.

 

[SMU]

Cracking ECM tonight that shows the heat plume building to the South & east - trying to push West with time.

 

There will be some 35C returns moving North at day 10 with maybe 32C just to the SE of the UK.....

 

http://www.meteociel.fr/modeles/ecmwf.php?ech=72&mode=1&map=0&type=0&archive=0

 

My references & posts have been intimating this as far back as 10 days ago.... a similar 2003 look.

 

If only.

http://modeles.meteociel.fr/modeles/reana/2003/archives-2003-8-10-0-0.png

[Captain Shortwave]

Pub run looks warm into the weekend

Looks a little further west with temperatures in the mid maybe high twenties in the south east.

Showers around, definite chance for thundery downpours, cape values look really good (but they always seem to do at this timescale)

Edited June 1, 2014 by Captain shortwave

[Man With Beard]

I've had a good look at the ensembles tonight and while calling a heatwave is still premature - still a few more unsettled options floating around - to deny that it might happen is simply not looking at the data. GFS ensembles have been rock solid for at least 6 runs now; 10C+ at 850hpa at this time of year is several degrees above normal, and the last 6 means have been above this mark for several days. ECM ens mean has consistently been showing the mean trough moving back into the Atlantic with a push of heights from the south = warm/hot. There's clearly a push from the south coming up - perhaps it will go east but when you get a decent build of heights, there is increased room for error in the placement of the warmer bits. I always call against implausible scenarios, but this one looks quite plausible to me. I'd say we're now looking 50%-60% chance of a very good warm spell next week onwards (though talk of 30C is extremely premature).

Edited June 1, 2014 by rjbw

[knocker]

Well I'm obviously  missing something on the ECM because I can't see why temps of 30C plus should be in the offing.

[SMU]

Well I'm obviously  missing something on the ECM because I can't see why temps of 30C plus should be in the offing.

 

If we get enough sustained flow from the S/SE with these uppers

http://www.meteociel.fr/modeles/ecmwf/runs/2014060112/ECU0-240.GIF?01-0

 

then temps would be aiming towards 30c.

[SW Saltire]

As a general rule of thumb, what kind of number should you add on to the upper temps to get the 2m? (At this time of year - I read someone state rough guidelines for winter which was useful) I'm sure I read 15 somewhere on here. So on the above chart 30/31 should be possible in the SE, IF those charts verified exactly as shown... Or am I wrong?

Edited June 1, 2014 by SW Saltire

[knocker]

As a general rule of thumb, what kind of number should you add on to the upper temps to get the 2m? (At this time of year - I read someone state rough guidelines for winter which was useful) I'm sure I read 15 somewhere on here. So on the above chart 30/31 should be possible in the SE, IF those charts verified exactly as shown... Or am I wrong?

 

There is no exact way of doing this without a Skew-T but 15C would probably be too high, This is obviously using the DALR. As a rule of thumb the average Environmental Lapse Rate (ELR) can be used which is 6.4C/Km. At the top end of the scale you could use the Dry Adiabatic Lapse Rate (DALR) which is 9.8C/Km but as the air will not be completely dry (humidty is taken into account) this will probably be too high. Assume an 850mb height of 1500m, or take the exact height from the model product and you can calculate the surface temp using the above. I would say 10-11C won't be a million miles away.

 

The affect of moisture can be seen easily because in saturated air the rate would drop to 5C/Km.

 

And yes if the advection was exactly as stated the temps would be headed in the direction of 30C. I was having a problem with the 32C-35C scenario.

 

It should also be noted this assumes a uniform lapse rate. If you have an inversion between the surface and 850mb then all bets are off. And you can get a super adiabatic lapse rate near the surface due to surface heating.

Edited June 2, 2014 by knocker

[phil nw.]

GFS ens means rock steady on the evolution towards Atlantic trough further west and a building Euro high.

 

 

now coming into the 10 day range,remember a few days ago this was showing 300hrs +.

Not sure about Steve's 35C on this as but 25C would be a ball park figure for now with the upper flow still more from the south west.

Not to say that greater heat could develop down the line if the upstream trough sharpens and the surface heat is drawn from the continent.

A good enough outlook though for many of us i would think as it stands.

[Man With Beard]

There is no exact way of doing this without a Skew-T but 15C would probably be too high, This is obviously using the DALR. As a rule of thumb the average Environmental Lapse Rate (ELR) can be used which is 6.4C/Km. At the top end of the scale you could use the Dry Adiabatic Lapse Rate (DALR) which is 9.8C/Km but as the air will not be completely dry (humidty is taken into account) this will probably be too high. Assume an 850mb height of 1500m, or take the exact height from the model product and you can calculate the surface temp using the above. I would say 10-11C won't be a million miles away.

 

The affect of moisture can be seen easily because in saturated air the rate would drop to 5C/Km.

 

And yes if the advection was exactly as stated the temps would be headed in the direction of 30C. I was having a problem with the 32C-35C scenario.

 

It should also be noted this assumes a uniform lapse rate. If you have an inversion between the surface and 850mb then all bets are off. And you can get a super adiabatic lapse rate neat the surface due to surface heating.

Really interesting analysis Knocker, I really don't have the knowledge you have - I can only rely on my experience, which is that +16C uppers, in June, combined with a dry southerly feed, sustained for more than a couple of days, in cloudless skies, will result in at least 30C being reached somewhere (perhaps 33C as a ceiling). I feel Steve Murr's analysis of the ECM was right, it's just that the ECM to me was the extreme end of what could happen. 

 

GFS ensembles this morning at T240: 

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=240:

not quite as convincing for a pressure rise but it's still the general trend.

 

ECM going hot again by T168:

Edited June 2, 2014 by rjbw

[Captain Shortwave]

ECM looks good for Saturday still

Warmest ups take until Sunday to clear.

 

Beyond that, ECM looks to be possibly holding it's evolution from yesterday

So very warm and potentially thundery Saturday, fresher but still pleasant Sunday with scattered showers before possibly turning very warm/hot next week (one hopes). 

Edit nope, it's a rinse and repeat plume set-up. 

Edited June 2, 2014 by Captain shortwave

[IDO]

As the synoptics suggested and BA's insight the ECM 12z op was an outrageous outlier for the latter stages:  

 

No change to the London ENS this morning on the GEFS; a warm up at the end of the week with above average mean temps for a good spell: 

 

 

If you ignore the outlier control run good consistency for a sustained pressure rise for the SE at least: 

 

There are precipitation spikes next weekend with the UK on the fringes of some very unstable air with the heat plume just across the Continent:

 

 

Need a correction west for the S/SE to feel the full force, but some ensembles show this still, though I suspect we may just get a glancing blow for the v. far SE/S/E. However from about T120 for around 2 days we have a front straddling the Midlands that has the potential for high precipitation; the GFS op reflects this:

 

ECM, with slight variations supports this scenario.

 

Good consistency from GFS, ECM and GEM for the Atlantic trough to establish in week 2 with it's associated Euro ridge:

 

 

 

Though there remains variations on that theme, with the GEM splitting the jet. The NOAA, as expected edges closer to that long wave pattern: 

 

 

 

 

 

 

 

 

 

 

 

[bluearmy]

Looks potentially very wet along frontal boundarys over the weekend and into next week. Going to be tough to pin that fairly narrow area down as it moves west to east and then south to north.

ECM ops are rarely in the wrong area day 6 so to see yesterday's 12z being backed up is not a surprise though the finer detail around the broad solution will be chopped and changed somewhat over the next few runs.

[lorenzo]

ECM back at it with garden path charts again?? Chase the Easterly becomes Chase the Euro Plume...with attendant joke fest media no doubt..!

 

At least something to watch out for as Hurricane season officially also begins. Looks like days 5-7 on the output are the ones to watch to see exactly what the mean troughing does, how much it backs west and dissipates versus lingering throwing the plume towards Scandi.

 

 

This morning at similar range and the trough appears to have more influence, another battle of the East vs West on the modelling...

 

[knocker]

Really interesting analysis Knocker, I really don't have the knowledge you have - I can only rely on my experience, which is that +16C uppers, in June, combined with a dry southerly feed, sustained for more than a couple of days, in cloudless skies, will result in at least 30C being reached somewhere (perhaps 33C as a ceiling). I feel Steve Murr's analysis of the ECM was right, it's just that the ECM to me was the extreme end of what could happen. 

 

 

Oh I don't decry experience rjbw. The higher temps than the theory in your example could well be the super adiabatic affect. Essentially this means, if working downwards from 850mb, there is a small layer near the surface that warms at a rate greater than the DALR thus the surface temp would be higher. I didn't have a problem with Steve's analysis, just thought it was pushing the envelope. Just in case it crossed anyone's mind I'm not trying to cause an argument.

 

EDIT

I should also have added that in your example the lapse rate could well have been above the standard ELR.

Edited June 2, 2014 by knocker

[bluearmy]

Let's all remember that post day 6, operational charts are only to be used for detail if they make sense wrt to ens and spreads.

The high resolution at which they run means that small errors at day 6 can become magnified Into large ones by day 10. If it looks wrong, given the suites that preceded it, that's because it probably is wrong.

[johnholmes]

compare the EC-GFS output this morning with the 6-10 NOAA I posted last evening (No 75) to see the problem.

No continuity or agreement with the 3 charts. If that is the case at 500mb then rest assured that the probability of getting the surface chart correct is more than usually fraught with difficulty.

EC is closer to the NOAA 6-10 than GFS is but NOAA does not show the fairly marked western trough/cut off that EC this morning and yesterday has. Of the 3 then I suspect that NOAA and EC are nearer the mark than GFS is in the 6-10 day range at 500mb so the surface output from EC may well be nearer the mark than the GFS output.

Too many differences to have any real belief in 10 days from now at the moment.

 

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

 

Having written all that the 00z synoptic outputs this morning from GFS and EC are not that different!

[Man With Beard]

ECM mean is another step towards settled weather. Upper trough recedes quickly between next Monday and next Thursday, ending in this:

[Summer Sun]

Still looking like a very warm end to the week if the low does begin to push back east then eastern regions could be in for some thunderstorms

 

 

By Saturday the warmest air is found in the east

 

 

t168 and t192 sees the warmth pushing in again

 

[knocker]

The ECM ens. Probably already been posted but I had to pop out to give an armful of blood. As JH mentioned really too fluid to call.

 

[vladthemert]

brave Knocker to goto dracula  seriously well done

 

GFS today saying next few days alot rainfall for penines region next few days could get 107 mm.

 

Edited June 2, 2014 by vladthemert