model discussion Model output discussion 11th July onwards

[jamesthemonkeh]

1 hour ago, Mike Poole said:

Going into this winter, the QBO is easterly (that doesn’t happen as often as it used to), we are coming out of a solar minimum.  So what can go wrong this year?  Indian Ocean dipole.  No.  ENSO, not sure, but probably not.  SSTs maybe:

 

Possibly also worth noting the cold anomoly in the North Sea - shame it doesn't apply to seas around the Baltic too though.  Not that I'd want to assume an easterly during winter.

[sheikhy]

Expecting gfs to move towards ecm and ukmo on the 18z......

[damianslaw]

2 hours ago, Mike Poole said:

Hello all!

There’s been talk of the Atlantic returning after months of absence.  I don’t see it.  I just can’t see a zonal attack on the UK that is any way prolonged.  

It is a mystery as to why zonal fayre has disappeared, last winter’s SSW might well have had something to do with it.  It didn’t deliver quite the patterns that most coldies wanted, but it did something, the question is what? 

Going into this winter, the QBO is easterly (that doesn’t happen as often as it used to), we are coming out of a solar minimum.  So what can go wrong this year?  Indian Ocean dipole.  No.  ENSO, not sure, but probably not.  SSTs maybe:

The hot seas in the eastern pacific (highlighted) may be bad news, but in the Atlantic we would expect to see a re-emergence of the tripole from summer, so I’m giving this a tick!!

Finally a look upwards:

Not much to talk about on today’s plot, but in a couple of week’s time the vortex looks like setting up shop - in a good place - for now.

I’m sure there will be much more to talk about as the cold season comes closer.

All the best, 

Mike

Perhaps not zonal, but meridional certainly so, and that has been the theme of 2021, anticyclonic followed by cyclonic/meridional and back again.. reason for the alternating cold and warm spells.. 

My calandar says Autumn begins on 22 September, and going by ECM/UKMO this evening, bang on cue autumn looks like it starting on time! Some cold uppers invading northern parts possibly by end of next week. 

[Allseasons-Si]

Evening all

not been on much of late as i have been watching the Iceland volcano,...a true spectacle that is

anyway's it does look like becoming cooler next week as the low transfers from west>east and we may pull in some cooler weather for a time from the NW as the low exits east of the UK (as it stands),i would love for the 12z gfs to be right but i can't see it as it's a major outlier and on it's own from the other models

the CPC/NOAA does show -ve heights N/NE of the UK on both the 6-10 and 8-14 day 500mb outlook with +ve heights NW Atlantic and up into S Greenland

now JFF i had to cherry pick one of the gefs ens out as it shows(in this local) a -6.6c uppers,...it is nice to see these cold charts but i will wait until winter,...THANKS!!!

have a great evening and weekend all

[Zenarcher]

I've been experimenting with an idea I've had for a while and finally figured out how to do it. One thing that's crucial in weather forecasting is trends and strong model agreement, but with so many models nowadays, obtaining a proper overview of everything can be a bit time consuming sometimes.

The aim is to combine all of the models into one image, giving you a quick and easy way to see what the best overall agreement is. I've been testing this technique over the summer and the last few days to make sure it works, and it seems to do a nice job at predicting future trends. Because it's a quieter time of year, I figured it'd be a good time to post it here. It makes use of most of the models available on the Meteociel website, including the GFS and ECM ensemble means, as well as the GFS control run. So we have 14 models in one image from 24 to 96 hours, 13 models for 120 and 144 hours, 12 models for 168 hours, and 9 models between 192 to 240 hours (up to 10 days outlook). I understand that it may not be everyone's cup of tea, but I find it beneficial in determining where the best overall agreement is, so others may find it useful as well.

Forecast over the next 24 to 72 hours (next 3 days) You'll notice the charts aren't perfectly clear because it's averaging 14 photos into one; the white lines are sharper on the first chart at 24 hours, but more spread out at 72 hours, as you go further ahead as the models gradually vary.

This weekend's forecast, there will be some rain on Saturday, but it will be a dry day in many locations. On Sunday, the outbreaks of heavy rain and thunder on the Eastern side of the country become a little more frequent. There may be some rain lingering in the South East of England by Monday, but high pressure will be rising across the country, bringing for the most parts a fine spell of weather.

     

Tuesday should be settled and dry for the most part, although there is a potential of more unsettled weather in the far north of Scotland. Low pressure will sweep in from the northwest on Wednesday and Thursday, bringing rainy and windy weather with it. The charts are becoming more muddled as they begin to differ even more, but you can still tell where high and low pressure is situated.

     

The longer outlook into the end of next week indicates the unsettled pattern continuing, with low pressure persisting, especially over the north, bringing more rain and wind, as well as cooler temperatures to the country.

       

Last but not least, an aminated GIF, and have a wonderful weekend everyone.

[Frosty.]

In my opinion the GEFS 0z mean suggests more of a glancing blow regarding the unsettled conditions later next week with the south largely escaping and the same is true of the Gfs 0z operational during the same period and further ahead, indeed the s/se could be warm as well as fine at times with most of the unsettled weather across nw / n Britain?…so, we may be looking at more of a nw / se split although this doesn’t preclude at least some rain affecting the SE from time to time?

[Scorcher]

Maybe the GFS run last night wasn't so outrageous at all? While an outlier, it picked up a trend for the low pressure to potentially miss the UK.

Who knows what could happen if further adjustments happen in subsequent runs.

[Singularity]

Tropical cyclone shenanigans in the northwestern N Atlantic for 2-3 days from now. How far north will it be? GFS furthest north, ECM furthest south, UKMO in between.

Generally, the further north it is, the more the Azores High is elongated east-northeast, across the UK, as opposed to more to the north with low pressure systems digging down across us instead.

[JBMWeatherForever]

Potential for a fair deal of early autumn warmth across the UK in the next few weeks. The colder northerly outbreaks seem to be trending less significant and high pressure more dominant.

[minus10]

Very noticeable the powerhouse of HP to the NE being signalled on the ECM 0z. This could certainly help to promote above average temps and stall the Atlantic systems. How long will it last?..

 

[Cambrian]

Some brilliant posts overnight and this morning.

The big differences between the ECM and GFS ops and the UKMO due to the vagaries of the ex-tropical storm in the western Atlantic take hold as early as between 72 and 96 hours on the 0z runs and is nicely illustrated by looking at the comparative drop in barometric pressure across northern Britain.

Looking at the Scottish central belt:

ECM 72h - 96h : 1024 falling to 1012

 

 

GFS 72h - 96h : 1026 (hardly) falling to 1024

 

 

UKMO 72h -96h : 1026 falling to 1016

 

[Methuselah]

11 minutes ago, JBMWeatherForever said:

Potential for a fair deal of early autumn warmth across the UK in the next few weeks. The colder northerly outbreaks seem to be trending less significant and high pressure more dominant.

Which would, hopefully, eradicate the relatively negative North Sea SST anomaly, which, in turn, may be a legacy of the cloudy August?

[Premiere Neige]

14 hours ago, Mike Poole said:

Hello all!

There’s been talk of the Atlantic returning after months of absence.  I don’t see it.  I just can’t see a zonal attack on the UK that is any way prolonged.  

It is a mystery as to why zonal fayre has disappeared, last winter’s SSW might well have had something to do with it.  It didn’t deliver quite the patterns that most coldies wanted, but it did something, the question is what? 

Going into this winter, the QBO is easterly (that doesn’t happen as often as it used to), we are coming out of a solar minimum.  So what can go wrong this year?  Indian Ocean dipole.  No.  ENSO, not sure, but probably not.  SSTs maybe:

The hot seas in the eastern pacific (highlighted) may be bad news, but in the Atlantic we would expect to see a re-emergence of the tripole from summer, so I’m giving this a tick!!

Finally a look upwards:

Not much to talk about on today’s plot, but in a couple of week’s time the vortex looks like setting up shop - in a good place - for now.

I’m sure there will be much more to talk about as the cold season comes closer.

All the best, 

Mike

However, there is a cooling trend going on in the area of the Pacific you mention...

[Methuselah]

10 minutes ago, Premier Neige said:

However, there is a cooling trend going on in the area of the Pacific you mention...

I think you've hit on something there, PN: wherever there's a strong anomaly, the trend will almost always be back toward the norm?

Edited September 18, 2021 by Ed Stone

[Premiere Neige]

13 minutes ago, Ed Stone said:

I think you've hit on something there, PN: wherever there's a strong anomaly, the trend will almost always be back toward the norm?

I'm hoping that area will cool further if la niña strengthens. It would be nice to not have a big fat high pressure sat in that area this winter.  COYS!

[damianslaw]

1 hour ago, minus10 said:

Very noticeable the powerhouse of HP to the NE being signalled on the ECM 0z. This could certainly help to promote above average temps and stall the Atlantic systems. How long will it last?..

 

Trouble is we have heights far to the west as well, and the pattern is meridional, the trough is destined to dig deep south between the two ridges. It's a highly 'meridional' flow. Increasingly colder air is wrapped under the southern flank of those heights to the east.. I guess if the ridge to the west moves further west we could end up with the trough further west and pull up a southerly, but look at the jestream it is digging far to the south.. The trough may split in situ though, end product could be a cyclonic flow with some warm uppers mixed in from the south. An interesting outlook after weeks of nothingness.

 

Edited September 18, 2021 by damianslaw

[Mark Smithy]

Now that the cricket season is drawing to a close I’ve spent some time looking at weather charts.

one thing has really struck me: is the GFS system normally this rubbish? It has been all over the place. This coming week is a case in point with its fervent desire to have a massive high pressure cell defying the actual facts that the others pick up.

[Methuselah]

Well, it looks as if the annual slide into Autumn is getting underway. But, not without one or two switchbacks along the way:

    

    

    

Not that that's in any way dependent on ONE GFS 06Z!

[Frosty.]

Just had a quick glance at the Gfs 6z op and I would say it’s generally a north / south split, changeable across southern u k but with some emphasis on fine intervals but more generally unsettled across the n / nw..does that sound fair?  …autumn May have found it’s mojo?.. ..just had a second glance.. …for sure there is some rain for all at times?…well it is autumn and I’m with the met office on this, autumn starts on September 1st…it’s like saying summer starts on June 21st or winter starts on December 21st..Bull Cr*p…nuff said!!!!!!!   

Edited September 18, 2021 by jon snow

[minus10]

1 hour ago, damianslaw said:

Trouble is we have heights far to the west as well, and the pattern is meridional, the trough is destined to dig deep south between the two ridges. It's a highly 'meridional' flow. Increasingly colder air is wrapped under the southern flank of those heights to the east.. I guess if the ridge to the west moves further west we could end up with the trough further west and pull up a southerly, but look at the jestream it is digging far to the south.. The trough may split in situ though, end product could be a cyclonic flow with some warm uppers mixed in from the south. An interesting outlook after weeks of nothingness.

 

Yes, interestingly the gfs 6z shows the jetstream digging down south later in the period with as you refer to a cyclonic flow developing which depending on where it sets up could result in anything from cool damp to warm and thundery    

As you say interesting times ahead with all to play for..

Edited September 18, 2021 by minus10

[Zenarcher]

Heavy rain will move in from the West tonight, sweeping over the country to the East, and the best weather will be in the West during Sunday, with some sunshine but heavy showers. Rain will fall heavily in the Eastern parts of England and Scotland. On Monday, a ridge of high pressure will move in from the South West, making it drier, but rain or showers may still fall in some parts of the East. Tuesday will be generally dry, with rain expected overnight, while Northern and Western Scotland will see windy conditions as low pressure passes to the south of Iceland. In some locations, gusts of up to 50 mph or more can be expected.

  

A band of rain is expected to move over the country on Wednesday, but England, particularly the Southern parts, should remain relatively dry. Looking ahead to Thursday and Friday, the models continue to show low pressure to our far North and high pressure to our West. The ECM, for example, sends a deep area of low pressure across the UK, bringing with it very strong winds and heavy rain, whilst the GFS and the UKMO show something less extreme, with low pressure about, making it unsettled but not as severe as the ECM.

  

The models mainly agree that things will stay unsettled through next weekend and the start of the following week, with low pressure persisting to our North that might move down and over the UK, bringing rainy and windy weather while temperatures are expected to drop. However, compared to those further North, the far South West and Southern parts of the country may occasionally avoid some of the unsettled weather.

   

Amination 19th Sept to 28th (average model outlook) 

[Cambrian]

06z GFS op - the GFS flinches first. It’s still more tentative in bringing us under the influence of low pressure next week, but it’s definitely shifted closer to the ECM and UKMO on this run.

Scottish central belt test Mk2

00z 96h : 1024mb / 06z 90h : 1018mb - much closer to UKMO now.

 

48 hours later, now bringing a northerly in to more of the northeast.

00z 144h / 06z 138h

 

Ex-tropical storm less intense, Azores high less intense, pressure 4mb lower across the UK and Ireland, with the trough sinking a lot further south over the North Sea.

[johnholmes]

2 hours ago, Zenarcher said:

Heavy rain will move in from the West tonight, sweeping over the country to the East, and the best weather will be in the West during Sunday, with some sunshine but heavy showers. Rain will fall heavily in the Eastern parts of England and Scotland. On Monday, a ridge of high pressure will move in from the South West, making it drier, but rain or showers may still fall in some parts of the East. Tuesday will be generally dry, with rain expected overnight, while Northern and Western Scotland will see windy conditions as low pressure passes to the south of Iceland. In some locations, gusts of up to 50 mph or more can be expected.

  

A band of rain is expected to move over the country on Wednesday, but England, particularly the Southern parts, should remain relatively dry. Looking ahead to Thursday and Friday, the models continue to show low pressure to our far North and high pressure to our West. The ECM, for example, sends a deep area of low pressure across the UK, bringing with it very strong winds and heavy rain, whilst the GFS and the UKMO show something less extreme, with low pressure about, making it unsettled but not as severe as the ECM.

  

The models mainly agree that things will stay unsettled through next weekend and the start of the following week, with low pressure persisting to our North that might move down and over the UK, bringing rainy and windy weather while temperatures are expected to drop. However, compared to those further North, the far South West and Southern parts of the country may occasionally avoid some of the unsettled weather.

   

Amination 19th Sept to 28th (average model outlook) 

Thank you, a fair amount of work has gone into that post, an interesting idea too. I'll keep an eye open for your next animation. Also be interesting to see just how close to the actual the video turns out.

Again my thanks

John

 

[Frosty.]

On 18/09/2021 at 14:57, Ed Stone said:

 

    

Just had a look at the mean on meteociel and to me it looks quite changeable, not full on unsettled but certainly some unsettled weather in it (especially further nw / n) and some less unsettled too with the south / southeast more favoured for the finer spells due to ridging between weather systems..pretty typical for the time of year and thankfully not the blocked snoozefest it was showing a few days ago..  blockquote widget

Edited September 19, 2021 by Paul
Removed quote from hidden post

[Frosty.]

Looking at the Ukmo 12h…the words glancing blow spring to mind?…  (A blow with less than full force that falls off to one side)…I looked it up!

Edited September 18, 2021 by jon snow