model discussion Model output discussion 11th July onwards

[Methuselah]

Oh dear, the GFS 00Z is being a very naughty boy!

    

    

    

[mb018538]

Let's have a look at the 00z...not a huge amount to cheer about really. Western areas could get a soaking Saturday, while a large area could get drenched Sunday with the slow moving low parked over the UK.



After the weekend the high probably won't end up in a favourable position for anything overly warm or totally settled with it being centred to the NW of the UK.

UKMO probably looks best, but even this is dragging in a load of muck and cooler air off the North Sea to spoil things for many.

[Guest]

Significant change in the profile of the GFS ensembles, only a couple of outlier keeping the mean above the LTA.

Despite a couple of warm days the Gfs Ops it would be dreadfully bad luck to end up with an upper trough planted over the SE for nearly a week like shown this morning however ECM and UKMO also toy with a residual upper trough being planted over the south east. Has to be said the chances over summer going out with a sparkle have to be almost zero this morning.  Seems more likely a northward regressing high is more likely, ECM takes it so far north by day 10 the uk again becomes a trough magnet. Is summer done? 
 

Edited August 17, 2021 by Blessed Weather
Final comment edited out.

[mb018538]

On 17/08/2021 at 08:11, Alderc said:

Significant change in the profile of the GFS ensembles, only a couple of outlier keeping the mean above the LTA.

Despite a couple of warm days the Gfs Ops it would be dreadfully bad luck to end up with an upper trough planted over the SE for nearly a week like shown this morning however ECM and UKMO also toy with a residual upper trough being planted over the south east. Has to be said the chances over summer going out with a sparkle have to be almost zero this morning.  Seems more likely a northward regressing high is more likely, ECM takes it so far north by day 10 the uk again becomes a trough magnet. Is summer done? Seems so. 
 

Don't think we're far away @Alderc. The fat lady is clearing her throat as we speak. This settled spell looked like going out with a nice plume a few days ago....but as you say - as the days have gone on, it's looking more and more likely the high will just get drawn up to the N/NW instead, leaving us in no mans land again (see below



14 days of meteorological summer left, and I'd be amazed now if we see anything over 30c. I'd say to everyone enjoy the slither of warmth (25/26c) we should see on Saturday before it all disappears. The rest of the ECM run today only sees national maxes of 18-21c, which is very poor, and continues what has been a forgettable August. Looks like September will have to bail us out again, and I'm quietly confident it will be another decent one.

[Iceaxecrampon]

10 minutes ago, mb018538 said:

Don't think we're far away @Alderc. The fat lady is clearing her throat as we speak. This settled spell looked like going out with a nice plume a few days ago....but as you say - as the days have gone on, it's looking more and more likely the high will just get drawn up to the N/NW instead, leaving us in no mans land again (see below



14 days of meteorological summer left, and I'd be amazed now if we see anything over 30c. I'd say to everyone enjoy the slither of warmth (25/26c) we should see on Saturday before it all disappears. The rest of the ECM run today only sees national maxes of 18-21c, which is very poor, and continues what has been a forgettable August. Looks like September will have to bail us out again, and I'm quietly confident it will be another decent one.

Yes enjoy from your IMBY point of view  - and I don't begrudge you one bit - seriously

We'll take what scraps of heat remain - we're used to deluges up Noooorth - all in all a very poor August.

 

 

[mb018538]

On 17/08/2021 at 08:47, Iceaxecrampon said:

Yes enjoy from your IMBY point of view  - and I don't begrudge you one bit - seriously

We'll take what scraps of heat remain - we're used to deluges up Noooorth - all in all a very poor August.

 

 

Apologies - I didn't really notice until you pointed it out that any warmth on Saturday could be fairly limited. Low to mid teens in Scotland looks ridiculously bad for the third week of August. 

[Andy Bown]

I genuinely want to know how modelling of rainfall can be so wrong at short range.

It was modelled on Sunday to be dry in the South until late Friday. Yesterday this changed to Thursday and still showed as such on UKV, Net Weather and GFS yesterday evening.

On waking this morning an area of showery rain was heading from Wales into Banes and Wiltshire. It’s been heavy several times in Trowbridge  (am outside  working in it, planned with others due to DRY FORECASTS!!) which is so poor.

Even poorer by Met Office was their app forecast showing dry all day for Trowbridge at 07.15 when it was blatantly obvious it would rain before 8! At least the Apple app was accurate at very short range!

I know Mother Nature does her thing to make mugs of us all, however I also thought modelling and forecasts were meant to be getting better!?

[Mark wheeler]

I'd certainly take the Navgem run this morning.

[SqueakheartLW]

GFS and GEM 00z for Saturday 21st August 2021

Quite some variation between the hottest and coldest ensemble members for Saturday 21st depending on the positioning of the high and low pressure areas and how quickly the low moves in from the west.

First the hottest members of both the GFS and GEM 00z runs

GFS 00z Member 4     2m Temp Max 24.7C     850hpa 10.6C

GEM 00z Member 7     2m Temp Max 28.4C     850hpa 14.5C

It would seem that the GEM is more keen to have a warmer Saturday overall across all of its ensembles compared with the GFS and its hottest member is much warmer than the GFS one. It seems the GEM is more keen to drag up warmer air ahead of the approaching area of low pressure. The main thing here with the warmest members is that the low progress is slower meaning more heat is pulled into the UK, especially England before the rain arrives and this could result in a more thundery breakdown of this heat, especially with the GEM option here. It could be quite a hot Saturday if the GEM option comes off but still warm if the GFS warmest option ends up correct.

Now the coldest members of both the GFS and GEM 00z runs

GFS 00z Member 6     2m Temp Max 16.4C     850hpa 9.2C

GEM 00z Member 14     2m Temp Max 20.3C     850hpa 8.9C

As with the hottest members it is the GEM option that is showing as the warmer option here in the coldest members. In the case of the GEM option here either the warmer air comes overnight when we see less impact on daytime maxes on Saturday so we end up sticking at around 20.3C as a max or the heat never really arrives in the first place but the progress of the low is clearly quicker here than in the hot option. The GFS is a rather cool option at only 16.4C as a maximum and in the case of this one it seems there is no pull of heat at all and instead we drag dull weather off the North Sea ahead of the low instead and bring in cloud and rain during Saturday that keeps temperatures well down.

[MATTWOLVES 3]

A few seem keen to discuss the ops and point out Summer is done. If your looking for an Heatwave,perhaps it is...but not if its the possibility of some decent conditions..The ensembles show GFS op was a little aggressive again. The ECM mean looks OK and there's decent ensemble support for those conditions also! Quite alot of ens support from the GFS also for a settling down..Last nights EC46 was positive also,and I'm not going to dismiss all that data this morning.

I'm not going to keep saying Summer is coming or it's over on here,all because I'm fed up by the way it's panned out! That's life unfortunately and we move on...but what I see this morning,is not all bad.

 

[JayAlmeida]

The closer we are getting the more this settled spell is looking less and less beneficial for the UK warmth/heat wise. Position of the high seems to change with each run and its never over the top of us (yesterdays GEM aside)

Today's GEM would be great if I lived in Iceland The decent uppers begin in the atlantic and finish to our far north and south completely avoiding us. Some decent warmth for Scotland by runs end but that's about it.

 

Edited August 17, 2021 by JayAlmeida

[JayAlmeida]

Don't like the look of this pesky low sitting around to our south on todays GFS runs either. The big three are not in agreement for how next week plays out. Wednesday and beyond looking to be the contentious part.

Edited August 17, 2021 by JayAlmeida

[mushymanrob]

LOL.... whilst the operationals are still flip flopping around all over the place, the general theme they are predicting is completely in line, broadly, with what the anomalies were predicting.

The latest charts.... the 6-10 dayer predicts the strongest high pressure yet to our near North. There is, on that, IMHO a likelyhood of the cool Northeasterly across most of England early next week and this is being shown on some operational runs.

The 8-14 dayer suggests the high will be centred (albeit weaker) further East than the previous chart. That would see warmer even hot humid conditions IF that chart is accurate and the high drifts East. This is at odds with the current GFS which suggests a more westerly base (leaving us cooler) whilst the current ECM suggests the high will drift further North.

Going off the Anomalies then, next week starts to settle down, a slow process as the weekend trough will be hard to shift, the southeast improving last. Cool, probably cloudy in eastern areas, sunniest and warmerst in the West with western Scotland faring best. As the high drifts East, we lose the Northeasterly as it backs Easterly then probably southeasterly.

So it should be warming up as the week progresses and a warm possibly humid bank holiday weekend is likely. But we do need a decisive drift East of the high.. so far imho its not quite there.

 

[MATTWOLVES 3]

 It looks to improve by day 6 onwards if you ask me,some uncertainty over where High pressure finally resides,but could easily shunt NE wards and bring us a decent lead up to the Bank Holiday.

Edited August 17, 2021 by Mapantz

[MATTWOLVES 3]

It looks like the Summer crew have given up the chase today

You know me,keep chasing till its mathematically impossible. I don't think anyone discussed the longer range EC46 last night regarding next month.. the 1st half looks quite poor with greater influence from Low pressure,quite alot of negative anomalies.The 2nd half looks more promising with stronger positive anomalies,and these very distinctive around the Scandinavian area...so Indian Summer perhaps not,more like a continuation of mixed conditions for our neck of the wood.

[BrickFielder]

Sea Surface temperatures across the Central Pacific are starting to have a bit of a La Nina look (cooler) and the Madden Julien Oscillation looks a bit stuck. This can be a sign of cooler weather for the UK.

CPC blocking forecasts suggest a blocking High shift from Greenland to Iceland, which can be tricky for weather models to get right. Often High pressure blocking suggested to our North slips eastwards in reality. ECMWF models differ in their interpretation of the signals , but both agree Azores High not really going anywhere. That Azores High will tend to drive a mobile low pressure system across the UK while it is not ridging towards Mid Europe. Temperatures look like having a North South split with periods of wet warmer weather for the South.

[Mapantz]

Keep it to model discussion!

Far too many point scoring / bickering posts.

[Tamara]

8 hours ago, Alderc said:

Is summer done?

I would recommend reading this for example :

 

4 hours ago, mushymanrob said:

LOL.... whilst the operationals are still flip flopping around all over the place, the general theme they are predicting is completely in line, broadly, with what the anomalies were predicting.

The latest charts.... the 6-10 dayer predicts the strongest high pressure yet to our near North. There is, on that, IMHO a likelyhood of the cool Northeasterly across most of England early next week and this is being shown on some operational runs.

The 8-14 dayer suggests the high will be centred (albeit weaker) further East than the previous chart. That would see warmer even hot humid conditions IF that chart is accurate and the high drifts East. This is at odds with the current GFS which suggests a more westerly base (leaving us cooler) whilst the current ECM suggests the high will drift further North.

Going off the Anomalies then, next week starts to settle down, a slow process as the weekend trough will be hard to shift, the southeast improving last. Cool, probably cloudy in eastern areas, sunniest and warmerst in the West with western Scotland faring best. As the high drifts East, we lose the Northeasterly as it backs Easterly then probably southeasterly.

So it should be warming up as the week progresses and a warm possibly humid bank holiday weekend is likely. But we do need a decisive drift East of the high.. so far imho its not quite there.

 

 

A good post which I agree with and very much fits well with the diagnostic viewpoint expressed by some of us of late. 

Also worth reading this:

3 hours ago, BrickFielder said:

Sea Surface temperatures across the Central Pacific are starting to have a bit of a La Nina look (cooler) and the Madden Julien Oscillation looks a bit stuck. This can be a sign of cooler weather for the UK.

CPC blocking forecasts suggest a blocking High shift from Greenland to Iceland, which can be tricky for weather models to get right. Often High pressure blocking suggested to our North slips eastwards in reality. ECMWF models differ in their interpretation of the signals , but both agree Azores High not really going anywhere. That Azores High will tend to drive a mobile low pressure system across the UK while it is not ridging towards Mid Europe. Temperatures look like having a North South split with periods of wet warmer weather for the South.

My own comments from the diagnostic viewpoint accord that numerical modelling of tropical convection becomes increasingly unreliable from about 5 days out in time. The GFS, especially has difficulties with amplitude and propagation biases.

All that said, trade winds have awakened once again across the Equatorial Pacific and based on the changes as briefly alluded to yesterday in relation to upwelling of cooler water to the surface, then the loner term trend is clearly more and more Nina-esque in direction of travel. This supports the amplified Pacific and downstream sequence  to corresponding amplified ridge in the Atlantic and the jet stream riding around this across NW Europe.

However, a default pattern is still subject to intra-seasonal factors and the monthly ENSO 'mini cycle' and as we have seen already this summer, can and often does assist temporary interruptions to the main theme.    That brings us back to the MJO forecasts and the caution adhered to those.

I suspect that the high frequency tropical wave will propagate to the Western Pacific and promote a temporary rise in angular momentum sufficient to get the GWO to Phase 4.  This, before the MJO likely beats a retreat c/o -ve inertia trade winds across the central Pacific and the GWO responds by returning to La Nina orbit phasing during September.

But within the limits of official summer itself, and with the above suggestions in mind -based on the rock solid aspect of the Azores high modelling within the context of the long term Nina-esque backdrop, it would nevertheless not take too much upturn in momentum transport to secure a more defined ridge from SW to NE and make the blocking structures advertised by the models to the north relatively less dominant than they appear in current NWP. modelling. The cooler air advection processes driving the troughing around the eastern perimeter of this high cannot be relied on to be accurately modelled, and it wouldn't take much to alter the alignment based on more forcing eastwards (for a short time at least) from the Azores High.

I think, for NW Europe prospects, an end of official summer fine and warm spell cannot be ruled out - even if longevity of this is to be questioned. For me here in SW Europe I continue to rely on the irrigation watering pump for my Mediterranean garden

 

Edited August 17, 2021 by Blessed Weather
Comment in first quote box has been edited.

[kold weather]

One more thing to throw into the mix is the development of Tropical storm Henri. Broadly the models haven't done a great job forecasting its southward extent and so Henri has managed to get into slightly warmer waters than some of the early cycles expected and therefore is stronger than predicted by quite a few of them already.

Its worth noting that out of all the models on the 00z suite, the GFS has got one of the better grasps it appears on the background conditions. As per normal in recent years ECM has been nearing rubbish status with clocking TC development. Henri has a pretty good chance of becoming a hurricane Fri-Sun based on the current set-up predicted by the models that have more accurately got the set-up right so far.

All this means I'd probably err closer to what the GFS is suggesting at this point as its likely handling the tropical injection coming early next week much better than the other models which broadly show only a very weak system (barely a TS) being absorbed and obviously the energy difference of a hurricane vs a weak TS is rather large!

 

[Methuselah]

Today's GEFS 06Z ensembles could have been a lot worse; I could have posted the ones with the exaggerated y-axis! 

    

[StingJet]

1 hour ago, kold weather said:

One more thing to throw into the mix is the development of Tropical storm Henri. Broadly the models haven't done a great job forecasting its southward extent and so Henri has managed to get into slightly warmer waters than some of the early cycles expected and therefore is stronger than predicted by quite a few of them already.

Its worth noting that out of all the models on the 00z suite, the GFS has got one of the better grasps it appears on the background conditions. As per normal in recent years ECM has been nearing rubbish status with clocking TC development. Henri has a pretty good chance of becoming a hurricane Fri-Sun based on the current set-up predicted by the models that have more accurately got the set-up right so far.

All this means I'd probably err closer to what the GFS is suggesting at this point as its likely handling the tropical injection coming early next week much better than the other models which broadly show only a very weak system (barely a TS) being absorbed and obviously the energy difference of a hurricane vs a weak TS is rather large!

 

One to keep a close eye on KW , for at present the proposed remnants of TS Henri once transitioned to "Ex Trop"  and subsequent absorption may hit the UK on BH Monday, as per the 06z GFS Op.

[MATTWOLVES 3]

UKMO day 7 not looking to bad after a partial inspection.. 

[mb018538]

Gotta love the UK. Low pressure has no problem at all whistling across the Atlantic and as far as the UK….before grinding to a halt.

3 days and it’s barely moved

[Mark wheeler]

11 minutes ago, MATTWOLVES said:

UKMO day 7 not looking to bad after a partial inspection.. 

Today's 6z Navgem at a similar time frame .

I'd take it over this afternoons GFS which is horrible .

Edited August 17, 2021 by Mark wheeler

[Mike Poole]

27 minutes ago, MATTWOLVES said:

UKMO day 7 not looking to bad after a partial inspection.. 

Yes UKMO good T144, but so different from GFS:

Uncertainty at this timescale, caution about concluding anything beyond this from the op runs.

Edit, add GEM at same time, and this one looks very good:

Tendency for the high to set up a bit further north than we might like initially.  

Edited August 17, 2021 by Mike Poole