model discussion Model output discussion 11th July onwards

[Mike Poole]

7 minutes ago, damianslaw said:

Not surprised at the lack of comments.. have we ever had such a benign September.. 'Wake me up when September ends'!

You always say that @damianslaw.  

I look at September in two ways, one is late summer-ish weather, like now, which I like, and any hints the models may be giving as to the colder season to come, so it isn’t boring, I think.  

Hey, hint, they are giving some hints right now in terms of the unusually very meridional jet…we will see…

Edited September 23, 2021 by Mike Poole

[Frosty.]

Yet another last hurrah of summer in early October on the Gfs 12z operational, temperatures are currently running approx 3 / 4c above average for the time of year across southern u k…impressive!

 

 

 

[Mike Poole]

Just a thought going further into Autumn, it might be worth switching to NH view on the charts earlier this year.  The interest now is most definitely over the whole of the NH not just our little bit.  

GFS T240:

Euro chart could be interpreted as some kind of Atlantic blow, but NH reveals it isn’t it, is just a low floating around in a more summer-like pattern.  

GEM T240:

Raging atlantic jet?  NH reveals there is absolutely nothing driving this at all.  

The NH is a total mess with no trace of a coherent vortex forming, and in my view this is due to a persistent blocking meridional pattern, which now can’t let go into Autumn, so use the NH charts to distinguish troughs/ low pressures affecting the UK, from the zonal atlantic onslaught - so much needs to change before the latter is even possible, in my opinion.  

Edited September 23, 2021 by Mike Poole

[Mapantz]

On 23/09/2021 at 18:23, Mike Poole said:

Raging atlantic jet?  NH reveals there is absolutely nothing driving this at all.  

The NH is a total mess with no trace of a coherent vortex forming, and in my view this is due to a persistent blocking meridional pattern, which now can’t let go into Autumn, so use the NH charts to distinguish troughs/ low pressures affecting the UK, from the zonal atlantic onslaught - so much needs to change before the latter is even possible, in my opinion.  

The same could've been said on this day back in 2013. We all know what the outcome of that was?!

[Mike Poole]

47 minutes ago, Mapantz said:

The same could've been said on this day back in 2013. We all know what the outcome of that was?!

This one compared to today, do you mean?

Mmm, a mere few similarities I grant you, on the pattern, some differences too of course.  But not sure on the background signals then, certainly not near solar minimum, it was only a burgeoning hobby for me at that time, maybe others would like to adjudicate!   

Edited September 23, 2021 by Mike Poole

[Mike Poole]

Trough looks practically done and dusted T144 on ECM:

For the south anyway…

Edit NH chart

Weird NH, is all I can say, but it does matter - down the line…

Edited September 23, 2021 by Mike Poole

[Mike Poole]

And then there were five….ECM T192:

Inevitable that as we run into autumn the wave number comes down, now to 5, and also, it is not clear on most NH Z500 plots where the jet stream is so it is always good to find one that is clear!  High over the Arctic too, crucial that…for this to whittle down to a wave 4 pattern in late Autumn…well us coldies hope!

Edited September 23, 2021 by Mike Poole

[Frosty.]

Just been looking at the GEFS 12z mean and to be honest it doesn’t look too bad across southern u k for much of the time, the Azores high predominantly ridges in close to the sw / s with the lower heights mainly to the nw / n with its associated unsettled weather…of course it’s not as straightforward as that but essentially it’s a northwest / southeast or north / south split through to the end of September into early October, this doesn’t mean the more unsettled weather across the northwest wouldn’t occasionally push further southeast but most of the unsettled conditions would be focussed on the nw / n?….anyway, in the meantime there’s still plenty of summer like weather to come further s / se before a squally band of rain pushes from west to east either Sunday night or during Monday with a drop in temperatures.

Edited September 23, 2021 by jon snow

[Zenarcher]

Today, we'll return to the Northern Hemisphere maps for our average model outlook for the next 10 days,

On Friday, low pressure will be to the north and high pressure is to the south, resulting in plenty of cloudy skies with rain outbreaks in the northern and western parts, but drier weather with a few sunny spells elsewhere. This weekend will be mostly cloudy, but there will be some sunshine for some areas. The best chance of seeing sunshine will be on Sunday, although there will be scattered showers all through the weekend. A band of rain will head in from the west on Monday, but after it passes, it will be followed by sunny spells and showers. Between Friday and Sunday, temperatures will remain warm, but Monday will be cooler.

   

Temperatures will remain cooler through the middle of next week, from Tuesday to Thursday. At this moment, it's unclear how unsettled next week will be, but it appears that there will be showers or rain in most parts of the country, and on Thursday, both the GFS and the ECM show low pressure crossing over Scotland, bringing widespread rain and wind to all parts of the UK. But it's still too far away, and it serves as an indication of how unsettled next week may be, depending on where these low pressure systems form and move. If that doesn't happen, expect a week of generally changeable weather on the unsettled side.

  

As we move into October next Friday and into the weekend, the trend is for things to continue unsettled, with more wind and rain on the way and temperatures remaining on the cooler side.

  

Latest amination, 24th Sept to 3rd Oct (Average model outlook, click to view larger, clearer image.) 

[Eagle Eye]

I will only do 1 run for September seeing as how it hasn't finished

September 3rd run

5th September

A typically close model run not too much difference especially in the high visible to my eyes, the low's strength changes a little bit throughout the models but positioning around this time is a concensus of all the models, statistically if the high happens the models seem to have a concensus as to the positioning of the high, the vast majority of differences in the high is the depth in which it goes into the south of England and especially how close it gets to Ireland.

Model agreement : 97%

 Outcome : 97%

Mostly the same, the small changes in the UK seems to be a slight south-west change

7th September

Low changes strength to north of Russia, whereas the high changing position is very slight across the UK, I find it weird how the low changes strength yet the high changes position rather than strength typically.

Model agreement : 88%

Outcome : 82%

GFS got this the worst in my opinion, the high's positioning changed against pretty much all models

9th September

A lot of difference in the ECM but less in the other models

Model agreement : 65%

Outcome : 58%

Finally

11th September

Model agreement : 44%

Outcome : 38%

I will write up my final post soon, the post putting all the statistics and what to look out for in the future

 

Edited September 23, 2021 by Eagle Eye

[MATTWOLVES 3]

Morning gang.

Just a quick look at the 46 anomalies moving forward...it trends more unsettled next week and perhaps into the following week,but dare I say it....turning more settled again as we move into the new month! How extensive this becomes is obvious open to debate at this range. But perhaps Heights never to far away from the South for some time.

So for me still no raging Atlantic onslaught...well not for a sustained and prolonged spell anyway!

Have a good evening,watching silence of the lambs is making me feel hungry. So it looks like a plate of beans and a nice chianti for me

[damianslaw]

2 hours ago, Mike Poole said:

Trough looks practically done and dusted T144 on ECM:

For the south anyway…

Edit NH chart

Weird NH, is all I can say, but it does matter - down the line…

Aleutian low and strong scandi/west Russia high.. have we just had a SSW.. these are two features you want in the bag when looking for a quick route to sustained cold. Unusual for late September when the PV should be gathering pace.. but not abnormal I guess. If this was late November it would be abnormal.

[damianslaw]

Not been keeping an eye on the trajectory of ex hurricanes.. but it's been an active season so far, yet we have yet to feel the effect of any storm system I.e no wind or heavy rain..yet they are having an opposite effect.. instead they have all tracked north into the Arctic aiding the absence of the Atlantic last 4 weeks and pulling in an airstream from SW to east. 

[Frosty.]

The Gfs 0z operational turns into a generally unsettled (cyclonic) run with spells of rain and strong winds interspersed with sunshine and showers, there are some drier intervals but not to be relied upon, more like suckers ‘ gaps between weather systems…as for temperatures, well, initially well above average across much of southern u k through to the end of the weekend (feeling more like summer at 22 / 23c…perhaps even 24c locally across the SE)  but then a marked drop from next Monday following a band of heavy rain and a generally much cooler more autumnal theme persists although there are a few pleasantly warmer days thrown in but nothing like the current warmth!…however, this is only based on this particular run and certainly doesn’t preclude further warm and fine weather coming back at some point beyond this week. 

Edited September 24, 2021 by jon snow

[Frosty.]

Maybe I’m wrong but the Gfs 6z operational seems a little less unsettled than the 0z op?..or perhaps that’s just my perception!.. ..anyway, if you like unseasonable warmth, enjoy it, it should last to the end of the weekend further s / se but then it becomes much more autumnal, more seasonal! ? 

[Zenarcher]

Afternoon all, a little of an early update from me today than usual, let's take a look at the next 10 days using the average model outlook,

Low pressure will eventually begin to take control of our weather over the weekend. On Saturday, clouds will break up more as the day goes on, allowing for sunny spells to occur in certain areas. Patchy cloud and sunny intervals are expected on Sunday, with showers. Highs in the mid-teens and low-twenties are expected, which is unseasonably warm for this time of year. A band of rain will move eastwards through the UK on Sunday evening and Monday morning, leaving sunny spells and heavy showers once it passes. On Tuesday, there will be a combination of sunshine and heavy showers.

   

Low pressure will persist over the UK from Wednesday to Friday, bringing cooler temperatures nearer to average for this time of year. The weather will be generally unsettled, with some sunshine and showers that might be heavy at times, and some areas will be a bit windy.

  

Looking ahead to next weekend as we enter October, it appears that low pressure will weaken further or move away from the UK, making the first few days of October a bit more settled.

  

Latest amination, 25th Sept to 4th Oct (Average model outlook, click to view larger, clearer image.) 

Despite the fact that there isn't much to talk about right now, as evident by the lack of posts in recent days, I noticed yesterday that the GFS predicted an ex hurricane in the Atlantic near the UK on October 7th,

 

It reappeared again this morning on the 06z GFS run, but this time much further west.

So I looked at the GFS ensembles and only about three of them out of thirty different runs showed it reaching the UK. Although it's still two weeks away and a lot will change between now and then and may even disappear completely in a day or two, I thought it was worth mentioning because it could be something to keep an eye on as we head into October.

 

[Mike Poole]

17 minutes ago, Zenarcher said:

Afternoon all, a little of an early update from me today than usual, let's take a look at the next 10 days using the average model outlook,

Low pressure will eventually begin to take control of our weather over the weekend. On Saturday, clouds will break up more as the day goes on, allowing for sunny spells to occur in certain areas. Patchy cloud and sunny intervals are expected on Sunday, with showers. Highs in the mid-teens and low-twenties are expected, which is unseasonably warm for this time of year. A band of rain will move eastwards through the UK on Sunday evening and Monday morning, leaving sunny spells and heavy showers once it passes. On Tuesday, there will be a combination of sunshine and heavy showers.

   

Low pressure will persist over the UK from Wednesday to Friday, bringing cooler temperatures nearer to average for this time of year. The weather will be generally unsettled, with some sunshine and showers that might be heavy at times, and some areas will be a bit windy.

  

Looking ahead to next weekend as we enter October, it appears that low pressure will weaken further or move away from the UK, making the first few days of October a bit more settled.

  

Latest amination, 25th Sept to 4th Oct (Average model outlook, click to view larger, clearer image.) 

Despite the fact that there isn't much to talk about right now, as evident by the lack of posts in recent days, I noticed yesterday that the GFS predicted an ex hurricane in the Atlantic near the UK on October 7th,

 

It reappeared again this morning on the 06z GFS run, but this time much further west.

So I looked at the GFS ensembles and only about three of them out of thirty different runs showed it reaching the UK. Although it's still two weeks away and a lot will change between now and then and may even disappear completely in a day or two, I thought it was worth mentioning because it could be something to keep an eye on as we head into October.

 

Yes, one to watch.  It is interesting with ex-tropical storms, one way in which they can affect our weather is indeed a direct hit on the UK and the concomitant strong winds and rain.  But it isn’t the most usual way.  That, it would seem to me, is that the storms mosey around in the Atlantic, while all the while helping to push up a ridge ahead which would be lesser if the storms weren’t there.  I wonder if this is the reason why UK Septembers are so often settled.  

ICON 12z has the low retracting by T180 compared to the 0z run, when it was all over us like a jellyfish.  

[Methuselah]

And another chance for a last-chance barbecue?

    

[Mike Poole]

Models at T144 on the 12z:

UKMO and GFS detract the low much more quickly than the others, and that probably explains the summery charts later in the GFS run.  

A look on the ECM NH view:

Aleutian low, east Scandi high, try get the vortex going against that, like driving with the handbrake on, and as early as this in Autumn.  Wave number not easy to determine on this plot, but probably still 5.  So a question to you - if the Atlantic is going to come barrelling through towards the UK in the second half of autumn, which it often does, how is that going to happen from this position?  By what mechanism?  Because I can’t think of one…

Edited September 24, 2021 by Mike Poole

[Cambrian]

12z UKMO accumulated total precipitation has an interesting story or two to tell.

Next 48 hours, higher totals in the warm sector of the incoming system confined to western parts of Scotland and Ireland.

 

During the following 4 days, by the end of next Wednesday (144h), up to 80mm over parts of west Wales (no big surprise there perhaps!), but look at that area of up to 70mm hugging the coasts of Suffolk, Essex and Kent.

On a closer look the heaviest of that falls early next Wednesday, up to 40mm in 12 hours. 

 

The UKMO forms a more pronounced little low further south along the clearing cold front as it exits the southeast, which just about shows up as a small feature on the Europe chart for noon Wednesday (120h).

 
 

The GFS develops a small low further north and out in the North Sea, and doesn’t deliver near as much rain to the southeast, so this will be interesting to follow.

[Liam J]

Some more interesting weather on the way as Autumn moves up a few gears in the coming days  

Numerous areas of low pressure look to affect us next week bringing wet & windy conditions. Risk of the first named storm of the season. 

Also noticeably cooler than it has been for much of September. A shock on the way  

 

[Weather Enthusiast91]

50 minutes ago, DisruptiveGust said:

Some more interesting weather on the way as Autumn moves up a few gears in the coming days  

Numerous areas of low pressure look to affect us next week bringing wet & windy conditions. Risk of the first named storm of the season. 

FullSizeRender.mov 20.17 MB · 1 download Also noticeably cooler than it has been for much of September. A shock on the way  

 

FullSizeRender.mov 14.27 MB · 1 download

 

I haven't been this excited about the weather in a very long time. 

Edited September 24, 2021 by Weather Enthusiast91

[Jamie M]

A trickle from CFS if you lot want it. 

[snow mad]

On 24/09/2021 at 22:18, Weather Enthusiast91 said:

I haven't been this excited about the weather in a very long time. 

Our summer had only just started here in east anglia. I was hoping for good warmth until the end of the month at least 

[Polar Maritime]

Tuesday could give some very active weather compared to late..