Model Output discussion 1st September 00z------->

[Frosty.]

The Ecm 00z op is superb again this morning and so is the ensemble mean, it really is as good as it gets for those of us hoping for a warm anticyclonic outlook with plenty of sunshine and light winds with chilly clear nights + mist and fog patches.

Edited September 22, 2015 by Frosty.

[knocker]

The latest EC32 update has HP in charge from Saturday until Sunday 4th October orientated mainly W/E before returning to a long fetch westerly airflow alternating between LP to the NW and HP to the SW. A not unfamiliar N/S unsettled/settled scenario.

[Frosty.]

The Gfs 6z shows high pressure building in from the southwest during friday and then the weekend and first half of next week show fine and pleasantly warm, sunny conditions, initially with light winds bringing a risk of mist and fog patches but not for long because during next week as the high drifts away NE the winds strengthen from the SSE but it stays fine with sunny spells until next thursday when rain spreads into the far west of the uk and then to the rest of the uk from next friday onwards when it becomes very unsettled with bouts of rain and strong winds interspersed by brighter but colder and showery conditions with a risk of showers turning wintry at times on the scottish mountains.

[Zenarcher]

Daily comparison using the GFS, ECM, UKMO, JMA, ICON, GEM, NAVGEM, NASA, CMA, FIM and the CFS all up to 240 hours along with the ECM and GFS ensembles. For each day whatever model has the most support will be shown for that time.

 

24 Hours Wednesday (ECM)

Low pressure remains over the UK and Ireland with another low pressure system to the West of Iceland making its way down to the North West of Scotland.

 

48 Hours Thursday (NAVGEM)

Low pressure sits to the North West of the UK it will start to move East while weakening and make its way to the far North of Scotland.

 

72 Hours Friday (JMA)

Low pressure remains over Northern Scotland but the rest of the UK and Ireland starts to see high pressure coming in from the South West.

 

96 Hours Saturday (GEM)

High pressure is expected to be over all of the UK and Ireland while another low pressure system forms to the South East of Greenland.

 

120 Hours Sunday (UKMO)

High pressure over the UK and Ireland continues to gain strength but moves slightly more East while the low pressure system near Greenland weakens.

 

144 Hours Monday (ECM)

High pressure still remains over the UK and Ireland while another low pressure system begins to form in the Atlantic.

 

168 Hours Tuesday (FIM)

While high pressure still remains over the UK and Ireland it starts to move East while a deep low pressure system sits in the Atlantic.

 

192 Hours Wednesday (FIM)

High pressure continues to move away from the UK and Ireland while the low pressure system in the Atlantic moves to the South West of Iceland and weakens.

 

216 & 240 Hours Thursday and Friday (FIM & GFS)

High pressure is expected to continue and move away but will remain close by.

 

[knocker]

The GEFS as eased it's position on the upper trough somewhat in six hours.

 

[Frosty.]

Having just read the met office update 6-15 day, they are still going for something like the ecm 00z op and ens mean which show a very settled and pleasantly warm outlook for most of the uk which lasts well into early October and nothing like the gfs 6z op which shows an Atlantic breakdown to very unsettled weather by the end of next week, potentially we could see the fine spell last a week longer than the 6z shows...let's hope the ecm and met office are right and we have a prolonged spell of quiet and warm weather through late September and early October.

[phil nw.]

Looking at the day 10 height anomalies from the ens runs there is no great appetite to wake up the Atlantic jet as we enter October.

The 3 images are t240hrs from NAEf's/ECM and GEFs(P)-parallel outputs.

 

all giving a similar picture of an area of high pressure around N.Europe from the UK towards Scandinavia into week 2.

Some variations will show over the coming days wrt surface features no doubt but the general idea of some sort of block developing from the south west building into the weekend is now showing on all the Op.runs.

It's just a question of how long this anticipated quieter spell may last and currently the ens. favour much of next week would remain largely under the influence of the high.

So today's outputs so far re-enforce last night's CPC chart for mean ht anomls. for day's 8-14 .

Certainly at the moment any Atlantic activity for next week looks very muted just a hint of troughing out west that currently looks slow moving.

 

 

[Polar Maritime]

The GFS continues to show the Atlantic push the block East as we enter the new Month.

[Scorcher]

The GFS continues to show the Atlantic push the block East as we enter the new Month.

 

It is very gradually moving towards the ECM solution within the reliable timeframe though- the Atlantic push is still in FI, and it's the GFS which is changing and not the ECM at the moment, which has been remarkably consistent.

 

For example, here is the comparison at around 120 hrs:

 

 

 

Now looking very similar for the latter part of the weekend- the evolution from there is where there is still disagreement though.

Edited September 22, 2015 by Scorcher

[Captain Shortwave]

The Euros continue to seem keen on building a robust and strong area of heights over the UK during the coming weekend and into the following week. Shown by the UKMO below.

That looks pretty good and in comparison to the ECM, there will likely be some very warm air aloft so in any sunshine temperatures would respond pretty well.

 

The GFS again never builds the ridge as strongly with lower 850s and consequentially brings a breakdown later on.

There seems to be an issue with the warm air tending to mix out and weaken the ridge, this not shown on the UKMO or ECM solutions over the past few runs. So at the moment we have the GFS which brings some drier and more pleasant weather before the Atlantic breaks through during the middle of next week, whilst the Euros show something much more prolonged and potentially very warm if we get a southerly vector to the wind. 

[Scorcher]

Yes CS that high being shown by the UKMO this evening, which is similar to what the ECM has been showing is going to take some shifting. The GFS is notoriously progressive with situations like this- I tend to worry when the Euros are showing a breakdown- but there is no sign of one from them. Let's see what the ECM throws up this evening- I predict more of the same.

[cyclonic happiness]

Just a quick question. What would be the chances of frost in the HP next week?

 

We still haven't got the heaters fixed in the glasshouses at work, so I'm being very attentive as to whether frost is forecast or not.

 

Thanks :-)

[Frosty.]

i'm pleased to say the GEFS 12z mean supports a more prolonged warm anticyclonic spell which lasts all next week with no premature atlantic breakdown as the Gfs 6z / 12z op runs showed, this is more in line with the earlier ecm and met office update. Hopefully the ecm 12z will be as good as the 00z.

 

PS..just my opinion but I don't think there will be any frost next week, just cool dewy nights with mist and fog patches developing and some areas staying clear.

Edited September 22, 2015 by Frosty.

[knocker]

That's more like it. GEFS back in the fold after that silliness.

http://www.tropicaltidbits.com/

 

[Polar Maritime]

Yes knock, It certainly wasn't taking any chances to say the least..

[Frosty.]

Ecm 12z looks anticyclonic, it also becomes very warm for the time of year for most of next week across the southern half of the uk, low to mid 20's c 

Edited September 22, 2015 by Frosty.

[blizzard81]

Ecm 12z looks anticyclonic, it also becomes very warm for the time of year for most of next week across the southern half of the uk, low to mid 20's c 

The models always struggle with the direction in which high pressure blocks drift. East? West? South? North? Etc etc. Ecm op tonight toys with the idea of drawing the high west by day 9, allowing cooler air to drift south eastwards across the uk. Just another possibility and no model will have a firm idea at that range as to where the high migrates, if indeed it migrates at all.

[knocker]

And all systems are go.

 

[ANYWEATHER]

Good Evening folks! After an unsettled week ,pressure builds for the weekend and into early next week. Good news ! The gfs model has been consistent over the last few days of a breakdown more or less from the south or south west next week around the middle of the week. Ecm in my opinion is really handling this badly as the ecm model is completely different at  T+216 12z is completely different from its 06z.   But of course the T+216 timeframe  is in la la land. But gfs in my opinion is on the money.......

[johnholmes]

And all systems are go.

 

Yes, 2 weeks or so of settled weather about 2/3 of the UK, exceptions possibly nw/w Scotland parts of nw N Ireland. The key for warmth and sun will be just where the surface feature sets up.

Edited September 22, 2015 by johnholmes

[Frosty.]

But gfs in my opinion is on the money.......

Why do you think the very progressive gfs op is on the money when the met office don't expect even a slow breakdown of the anticyclonic spell to occur until at least 7th October? The Gefs 12z mean looks set fair from this weekend until the week after next, in my opinion most of the uk away from the far northwest is going to have a prolonged very pleasant spell with potential for unseasonable warmth.

Edited September 22, 2015 by Frosty.

[ANYWEATHER]

Yes, 2 weeks or so of settled weather about 2/3 of the UK, exceptions possibly nw/w Scotland parts of nw N Ireland. The key for warmth and sun will be just where the surface feature sets up.

Hi John, what model are you looking at , A two week settled spell  I cant see!!???

Edited September 22, 2015 by ANYWEATHER

[Geordiesnow]

I would not like to call on a 2 week settled spell either, especially when you got tropical storms lurking which could interact with the weather patterns however it does seem at least for Saturday and Sunday, it should be fine, settled and dry, touch and go regarding any fronts in the far North West but hopefully any frontal clouds will stay off shore.

 

Regarding frosts, I think the main chance will be this weekend as the uppers are at its coolest then but even then, its not true proper polar maritime air(850 temps 0 or below is polar maritime air) and the uppers do tend to warm up as the weekend goes on and potentially next week, the uppers are forecast to go even higher up to 10C hence forecasts of temps potentially climbing as we head into next week and I would imagine the chances of frost will reduce. 

 

That is uncertain and by no means a guarantee at this range because of how tropical storm Ida will interact with the weather pattern and there is also hints the high could head northwards around Scotland which pull in a more cooler Easterly flow thus upper air temps are more modified therefore temps are cooler more widely.

[damianslaw]

High pressure is notoriously fickle in where it decides to position itself, and conditions underneath it can be very different due to subtle changes in its position, meaning the difference between a cloudy murky sky and a gin clear blue sky and plenty of sunshine. Keep an eye out for ex tropical storm development over the mid atlantic (Storm Ida) I believe, such systems can easily disrupt things when they get caught up in the jet - the projected path of the jet would send such system to our NW but then quite easily SE to our shores pushing the high out to the west. Far from certain we will end up with a lengthy settled spell. The Jetstream has a lot of oomph to it at the moment and the propensity for much of this year has been for the longwave trough to anchor itself to the NW but then drop SE over our shores, strong heights to the north would help trigger such developments once again.

[knocker]

And the ecm is also on the money with perhaps an intrusion to the NW later in the ext period.

Edited September 22, 2015 by knocker