model discussion Model output discussion 11th July onwards

[Climate Man]

51 minutes ago, mb018538 said:

Tropical forcing vs La Niña….one wants to build, one wants to retrogress. Conflicting signals, chaotic output!

Which renders the mean output useless as it is the sum of extremes. Perhaps not useless but not something to hang your hat on.

[SqueakheartLW]

37 minutes ago, Alderc said:

And for something completely different, snowfall anomaly forecast for the coming winter! Good news if you ask me! 

Good news for those who want below average levels of snow that is which for me means a bad winter

[Mike Poole]

49 minutes ago, Alderc said:

And for something completely different, snowfall anomaly forecast for the coming winter! Good news if you ask me! 

Far too early to be taking model predictions for this sort of thing for winter seriously.  As any winter enthusiast would well know.  

[Captain Shortwave]

The GEM evolution looks unlikely given the handling of the low this coming weekend differs from the rest. As it gets absorbed by the trough to the west it allows the Azores high to build north east creating a more Euro/Scandi high motif.

Days 5 and 7

   

If the UKMO/ECM are right then Saturday looks decent;

 

The UKMO suggests that this low will crawl eastwards so by Sunday the low is situated just to the west of the U.K. though likely to bring unsettled conditions to most, though it should stay warm with winds from the south. We will see how the ECM handles this in a bit.

Edited August 16, 2021 by Captain Shortwave

[MATTWOLVES 3]

54 minutes ago, Alderc said:

And for something completely different, snowfall anomaly forecast for the coming winter! Good news if you ask me! 

Bloody hell Chris you can't be playing down Winter just yet,let me remind you,the cold chasing crew on here are an unforgiving bunch...Best to keep em sweet mate

Ps the GFS control was a corker if you like a little bit of Higher pressure.

[Guest]

22 minutes ago, Mike Poole said:

Far too early to be taking model predictions for this sort of thing for winter seriously.  As any winter enthusiast would well know.  

Off course not, still it didn’t stop people getting excited over a New Year’s Eve CFS chart showing biting easterlies (which has already happened several times this summer). Off course no one ever pointed it out, it just got about a million likes….

[MATTWOLVES 3]

12z looking similar to the 0z.

[Frosty.]

The longer term ECM 12z operational looks very nice doesn’t it? ...high pressure / strong ridging during late August would be just the ticket..you don’t need blazing heat for summery weather, dry with warm sunshine would be good enough!!!!!  

Edited August 16, 2021 by jon snow

[damianslaw]

1 hour ago, mb018538 said:

Tropical forcing vs La Niña….one wants to build, one wants to retrogress. Conflicting signals, chaotic output!

Those who like cold would relish both prospects in winter.. alas a very different outcome in summer, cool or heat in order.. 

[summer blizzard]

Euro goes for a middle ground that would end up like the GFS as cool air is coming round the back.

[Mike Poole]

12 minutes ago, MATTWOLVES said:

12z looking similar to the 0z.

I think if you took that as the best estimate, with uncertainty either way, including the HP being less influential, or on the other hand an alignment out west that delivers a plume, that is probably including all options from today’s runs.  

[Methuselah]

Crikey, what a mess! Seeing Uppers range from -2 to >21C doesn't fill me with confidence. Something (I know not what!) is afoot?

    

[Kirkcaldy Weather]

13 minutes ago, jon snow said:

The longer term ECM 12z operational looks very nice doesn’t it? ...high pressure / strong ridging during late August would be just the ticket..you don’t need blazing heat for summery weather, dry with warm sunshine would be good enough!!!!!  

Matches well with phase 2 of MJO 

[Frosty.]

The JMA 12h gets my vote!... ️ ?  

 

[Uncle_Barty]

3 hours ago, Tamara said:

There is nothing to change this thinking. Not even the bizarre 'law of sod' methodology which overtakes this thread.  

So, to the diagnostic.The GWO, subject to 2 day lag, has been orbiting to low angular momentum phases, circa Phase 2,  following the downward momentum drift that began in late July - not coincidentally the time that the fine, very warm spell broke down in the UK and other parts of NW Europe.

The 40 day phase plot clearly depicts the ascendency of momentum during the first half to two thirds of July, and the steady improvement from the unsettled start to the month to that late month breakdown.

Despite this, there remains the opportunity for a third fine summer spell c/o ridging into the last phase of this month for NW Europe to see official summer out in a way that it began. As suggested in the previous post, its a case to what extent the high frequency tropical wave can, temporarily, diffuse the underlying Nina-esque standing wave which continues to develop as the Pacific maintains upwelling effects of cooler water to the surface.

 

 

 

 

Is this a reference to the MJO moving through Phase 3 into Phase 4? Or perhaps I have the wrong end of the stick, as this still suggests a lack of convection over the E Pacific (cold SST anomaly/Nina) confirming the pattern rather than temporarily diffusing it?

Edited August 16, 2021 by Uncle_Barty

[stodge]

Evening all

With this morning's Daily Star telling me it's going to be 31c by the end of the month, I'm looking for those +20 850s on this evening's charts.

Let's see what we do have at T+216 in terms of 850s from this evening's 12z output.

T+216 is Wednesday August 25th

Respectively GFS OP, GFS Control, GEM, JMA and ECM

Once again, GEM is the slight outlier keeping heat closer while all the others, frankly, don't.

Now, let's not get carried away - the prevailing synoptic is to develop strong HP to the north of the British isles which means an E or NE flow so for the west it's going to be very good indeed with plenty of warm sunshine and hopefully any low cloud will burn back to the coasts early further east.

It's what I call "San Diego" weather in reverse and frankly it's my favourite type of weather - low humidity, pleasant sunshine etc. I'd much prefer it to stifling heat and high humidity. GEM and to an extent JMA have more of an ESE so draws off warmer air with a short fetch across the cooler water. Entirely possible and oddly enough in midwinter, my favourite scenario for cold for the south east.

Other models build the HP more to the north than north-east so the flow is more across the North Sea with a longer fetch.

All in all, I like what I'm seeing tonight - if GFS in particular verifies, it's going to be very amenable weather.

Glancing out to the end of the month for a bit of fun GFS OP and Control at T+360.

One of the things I've observed this summer has been the persistence of LP over North Africa feeding into southern Europe. This has left heights further north than normal and has left Europe and southern Britain facing more thundery outbreaks.

If you were to posit a shift of synoptic patterns north in response to a warmer world, this might be what you would see. The heat build up over North Africa manifests with heat LP as we see over desert southern California and pre-monsoon India. The HP response is to sit further north or west - it's most evident on GFS Control when the LP waxes north and creates instability over western and north western Europe - the outcome is heat and storms. You see the same in Southern California, Nevada and Arizona when humid unstable air moves up from Mexico - heat and storms. 

This is aided and abetted by a moribund Atlantic and a lack of energy to move the synoptic pattern.

 

 

[SqueakheartLW]

Who wants GEM 12z Member 13 to verify for next week. Consistently at or above 15C at 850hpa for 7 days in a row along with mid to upper 20C's by day and mild to warm nights as well

Those 850hpa temps are remarkably consistent next week close to or above 15C, well above the ensemble mean and even further above the long term mean too.

Look where Member 13 sits compared with the GEM 12z ensemble mean 2m temps

23rd August     850hpa temp 11.5C     2m temp max 24.8     2m temp min 13.6C

24th August     850hpa temp 15.2C     2m temp max 26.8     2m temp min 13.5C

25th August     850hpa temp 17.0C     2m temp max 26.9     2m temp min 14.0C

26th August     850hpa temp 17.5C     2m temp max 24.6     2m temp min 16.4C

27th August     850hpa temp 17.9C     2m temp max 24.0     2m temp min 14.7C

28th August     850hpa temp 18.0C     2m temp max 26.9     2m temp min 12.0C

29th August     850hpa temp 18.1C     2m temp max 24.9     2m temp min 11.8C

30th August     850hpa temp 15.4C     2m temp max 23.5     2m temp min 15.0C

[Mike Poole]

6 minutes ago, stodge said:

This is aided and abetted by a moribund Atlantic and a lack of energy to move the synoptic pattern.

 

 

Good post.  How long has this lack of Atlantic energy been going now, it seems like November last year?  I know various people have moaned about summer, but I don’t think a raging Atlantic has ever been part of the problem, it has more been stuck patterns slow to clear.  And maybe now the stuck pattern will be a favourable one.  

Autumn is now absolutely key for me, if the Atlantic doesn’t break through then, I think one more piece of the winter prediction jigsaw falls into place and it is a big one.  The models can tell us nothing at this range, but the longer term drivers such as EQBO and Atlantic SST tripole are hinting at something interesting.  My main concern at the moment is we don’t hit something like the Indian Ocean Dipole like 2 years ago that just scuppers what are shaping up to be good signals.  Long way to go yet, of course.

[SqueakheartLW]

Who wants to see uncertainty to the core here. GFS 12z for 27th August at 270 hours away

Hottest Member     Member 20     850hpa Temp 20.5C     2m Temp Max 32.0C     2m Temp Min 20.6C

Coldest Member     Member 9     850hpa Temp 0.0C     2m Temp Max 16.9C     2m Temp Min 12.3C

If there's this much spread just for later next week then what can we rely on at the moment. So many conflicting signals to get this much spread in the output. A spread of 20.5C on 850hpa temps and a range of daytime maxes between 16.9C and 32.0C and mins between 12.3C and 20.6C.

Edited August 16, 2021 by SqueakheartLW

[Scorcher]

3 hours ago, mb018538 said:

 

I can guarantee you that chart isn’t warm and sunny for a good portion of the southern half of the UK…GFS has this upper low crossing too, which brings lots of heavy rain:

You're always a big fan of those rainfall charts at long range though- they are often very misleading as we saw earlier in the summer.

[Mike Poole]

ECM mean and spread T240:

This is a massive shift back to a warm and settled pattern at this range, position of the high on the mean excellent, and the low spread over the entire UK equally telling.  Those who were calling for the end of summer, are going to be disappointed.  

[Frosty.]

Looking at the coming weekend, tonight’s ECM 12z ensemble mean suggests a plume or at least plume lite? ...with very warm humid air drawn up from the near continent with thundery potential?..and then becoming more settled / blocked further ahead...I continue to believe next week will become better than anything we’ve seen so far this month and hopefully that will continue right to the very end of august!!!  
 

ps.. I’ve mentioned about Scandi heights quite a lot in recent weeks regarding late august..could be looking good! 

 

 

Edited August 16, 2021 by jon snow

[MATTWOLVES 3]

Just to add some weight to Karl's post above...tonight's EC46 going for quite a strong build of Heights into scandy next week..so we kind of end up with a potential Estly feed and becoming rather warm with it.....certainly no Atlantic breakthrough on the cards next week...Still looking good for something much better next week.

Oops...Low pressure threatening to mess up the Bank Holiday period somewhat...long way off..but it would hardly be a suprise would it!

The 46 anomalies are highlighting a very strong build of pressure to our NE...be interesting to see how that plays out.

Edited August 16, 2021 by MATTWOLVES

[Kentspur]

1 hour ago, Ed Stone said:

Crikey, what a mess! Seeing Uppers range from -2 to >21C doesn't fill me with confidence. Something (I know not what!) is afoot?

    

Sounds a bit like trying to predict if our Spurs are going to turn up on the day haha. Well atleast the ensembles show a clear rise in 850HPA temps in the reliable 5day period, before the op run goes to the lower end of the pack

[Mike Poole]

Well there is a lot to pick the bones out of on the ECM clusters.

Let’s start with the T192 to T240, and there are 6!:

Worth noting up front 17/18 charts have the red scandi blocking border, only the last one on cluster 6 moves back to Atlantic ridge (purple).  So strong support for the high pressure to migrate to our east to some extent.  All of the scenarios have some kind of heights in the UK, as you would expect from the mean and spread I posted earlier.  If some warm up doesn’t come of this I’ll eat my pizza.  

5 clusters for the later T264+

The high pressure scenario there in the first two.  But by now we are getting so far from reality.  I think the mean and clusters bode very well for a hot spell to end summer, but there is uncertainty and that is what the T264+ clusters show.  

All in all, while some of the op runs might have occasionally gone rogue, the picture is showing a high pressure dominated regime from late next week for a fair few days….temperatures, well, depends on the exact location of the high.  I’m optimistic of some real summer heat at the end of the season.

Edited August 16, 2021 by Mike Poole