Model Output Discussion 26/08/2012

[Summer Sun]

Yes looks like a quick transition to a cool Autumnal set up this year. I do think that we will not see the the 20c temp being broken now until next year.

There is still ample time for some where to get 20c yet where only in mid September remember next weekend gets very close in the south

Edited September 16, 2012 by Summer Sun

[bluearmy]

Yes looks like a quick transition to a cool Autumnal set up this year. I do think that we will not see the the 20c temp being broken now until next year.

brave call snowflakey and likely to be wrong i think. its only mid september and with a trough looking likely to set up just sw of the uk and a ridge to our east, i suspect some warmer days are inevitable.

[Backtrack]

Yes looks like a quick transition to a cool Autumnal set up this year. I do think that we will not see the the 20c temp being broken now until next year.

Hmm, let's just keep in mind that 20C can be achieved in November? A pretty silly call if you ask me...

[William of Walworth]

I'm dreading a washout next weekend,

(which for me will start on Thursday, in the York./Lincoln areas)

But it seems more likely than not that there could very well be one, on the most recent runs ....

[Frosty.]

I don't think i'm buying what the gfs 6z is showing today, it just looks too settled and rather warm at certain times in the first half of the run and having just read the latest meto update which is right up there with one of the most unsettled and rather cold looking outlooks that you could ever expect at this time of year. I think the 6z is just plain wrong, especially compared to the ensemble mean so let's see what the 12z shows.

Edited September 16, 2012 by Frosty039

[Aaron]

Hmm, let's just keep in mind that 20C can be achieved in November? A pretty silly call if you ask me...

And -27C can be achieved in January, but I don't expect it to happen in my lifetime again.

[damianslaw]

Models are suggesting quite a cool unsettled outlook as we see a flow from between north and west rather than south and west, which at this time of year means chilly with showery rainy episodes and risk of frost in sheltered spots more so parts of the north. By the end of next week the models are showing quite a deep low pressure tracking down from the NW with its associated trough, meaning a potentially very unsettled wet windy and cool weekend with the first proper snows of the season for the higher parts of the Highlands. Before then we have a number of rather chilly showery days ahead with rain in the north and cool nights - very early autumnal.. and just what you might expect as we head towards the autumn equinox.

Longer term as we enter the latter part of the month, the models are keen to develop a robust mid atlantic high locking us into a rather chilly unsettled flow from the NW with every threat of the first cold northerly blast of the autumn occuring before the month is out - certainly no suggestion of the azores high influencing conditions once again, nor of heights building over the country or to the south and east, very much trough over and just to the east of the country. It could be a cold end to the month..

[Weather Boy]

I don't think i'm buying what the gfs 6z is showing today, it just looks too settled and rather warm at certain times in the first half of the run and having just read the latest meto update which is right up there with one of the most unsettled and rather cold looking outlooks that you could ever expect at this time of year. I think the 6z is just plain wrong, especially compared to the ensemble mean so let's see what the 12z shows.

Yes, I am very puzzled in what I see as a contradiction between the synoptic charts currently being provided by all the main models on one hand, which shows an at worst mixed outlook with a NW flow but with pressure to high to bring substantial rain (for the period mid-week to the end of the weekend); and the fax and met office predictions on the other hand which is firmly in the unsettled wet and windy camp. It is not as if the models are a one off rogue run as they have been saying this scenario since at least Thursday.

I have to declare an interest as I am walking in the Yorkshire Dales over that period and I am very puzzled.

I have begun to lose some faith in the Meto medium or long range as they seem to say unsettled all the time, pretty much regardless of the models or other signals. However, they are very firm on this, so I fear them to be right.

[Eskimo]

And -27C can be achieved in January, but I don't expect it to happen in my lifetime again.

Totally agree, 20C can be achieved but rarely, 21.7 is an all time record.

[IDO]

Models are suggesting quite a cool unsettled outlook as we see a flow from between north and west rather than south and west, which at this time of year means chilly with showery rainy episodes and risk of frost in sheltered spots more so parts of the north. By the end of next week the models are showing quite a deep low pressure tracking down from the NW with its associated trough, meaning a potentially very unsettled wet windy and cool weekend with the first proper snows of the season for the higher parts of the Highlands. Before then we have a number of rather chilly showery days ahead with rain in the north and cool nights - very early autumnal.. and just what you might expect as we head towards the autumn equinox.

Longer term as we enter the latter part of the month, the models are keen to develop a robust mid atlantic high locking us into a rather chilly unsettled flow from the NW with every threat of the first cold northerly blast of the autumn occuring before the month is out - certainly no suggestion of the azores high influencing conditions once again, nor of heights building over the country or to the south and east, very much trough over and just to the east of the country. It could be a cold end to the month..

I agree with most of the above; 5/6 days of settled HP dominated weather for the south. Then 5/6 days of cooler LP influenced outlook. However both the GFS 0z and the 12z seem to say from around the 28th September HP edges in again to the south, bringing in southerly winds and above average temps. The GFS 12z still has us under this influence on the 2nd October. So I am not sure of a cold end to the month.

http://www.evernote.com/shard/s19/sh/51ab0fe4-5ccf-4b68-9cf5-8c63ceccd6f5/3946791ebef3aba93a1157d0ea060619

All in FI but pattern wise GFS are hedging in that direction.

[Dorsetbred]

Yes looks like a quick transition to a cool Autumnal set up this year. I do think that we will not see the the 20c temp being broken now until next year.

I wouldn't give up yet, especially down here, we are still still hitting that figure, (yesterday was 21.4C)

Although it has be acknowledged a turn to the NW as suggested will certainly cool things down, even down here

Seasons change time I think.

Edited September 16, 2012 by Dorsetbred

[MP-R]

Totally agree, 20C can be achieved but rarely, 21.7 is an all time record.

There's more of a chance of 20C in October than -27C in January to be fair, especially in the south. London probably has a day or two of 20C every year as London just stays warmer all year round, as I have experienced. The GFS shows how this can happen with a high pressure cell just to the east o the UK with southeasterly or southerly winds coming up the western edge.

[Eskimo]

There's more of a chance of 20C in October than -27C in January to be fair, especially in the south. London probably has a day or two of 20C every year as London just stays warmer all year round, as I have experienced. The GFS shows how this can happen with a high pressure cell just to the east o the UK with southeasterly or southerly winds coming up the western edge.

We were discussing November lol

[Summer Sun]

Could be heading for a decent weekend for some if tonight's UKMO is correct

Edited September 16, 2012 by Summer Sun

[SnowObsessor90]

One trend seems to be rather consistent lately across all the models is that diving low being pushed further and further back, I wonder will it end up arriving at all?

[Fozfoster]

If this was the two word story thread.........................CHERRY PICKING.

Could be heading for a decent weekend for some if tonight's UKMO is correct

If this was the two word story thread.....................

CHERRY PICKING

Edited September 16, 2012 by Fozfoster

[chionomaniac]

Not really Foz. The latest ECM is very similar at T+144. But after that a trough takes full control.

[Fozfoster]

Not really Foz. The latest ECM is very similar at T+144. But after that a trough takes full control.

Ok C, back under my rock.

[Gibby]

Good evening. Here's another attempt to decipher the models from the 12ZS from Sunday September 16th 2012.

From now until Thursday all models seem agreed on a generally cool and somewhat showery NW flow over the UK with the heaviest and most frequent showers in the North and West of Britain. By Thursday all models show something of a weakening trough moving down from the North with a spell of rain and showers for all albeit briefly and light in the SW.

GFS then moves into the end of the week and weekend with a slack pressure gradient over the UK ahead of Low pressure slowly sinking SE from Iceland. This trend continues with low pressure settling over Britain for several days before a ridge dries things up for a while. Late in the run a North/South split develops with Low pressure to the North and High to the South with rain bearing fronts crossing all areas though the heaviest rain reverting back to Northern locations.

The GFS Ensembles show 850's a little below normal throughout the run though not by much. From the 21st in the South it becomes quite wet at times before amounts of rain lessen a little again later. Further North 850's also remain close to the long term mean with rain at times throughout the run some of it heavy. the operational appears to be one of the cooler options North and South.

The Jet Stream blows across the UK currently which is maintained for several more days before things become diffuse for a while. hints of the flow are still shown South of the UK in a week or so time.

UKMO at midday next Saturday shows High pressure over the South with a strengthening Westerly flow over Scotland extending slowly South with rain later in North and West Scotland.

ECM also looks similar at 144hrs moving forward to extend Low pressure South to engulf the UK in the early and middle days of the following week bringing showers and longer spells of rain to all in cool and sometimes windy weather.

In Summary the models are still struggling somewhat in the synoptic pattern at the end of this coming week. However, they eventually all agree on Low pressure coming down from Iceland over the UK late next weekend or in the early days of the following week. In the meantime there are a good few days of fairly benign conditions to go through and although most places will see a little rain at times over the coming 5-6 days amounts look like being small for many away from the far north.

[johnholmes]

Having a close look at the troughs/ridges on the predicted 500mb anomaly charts over the last 3-4 days and there are 3 troughs from the west coast of America to the UK with one other about mid way between the meridian and the far west trough, so 4 in all. That is just about as stationary a wavelength as its possible to get. This from 100's of checks done many years ago long before computers to give forecasters some idea of the possible changes in the atmosphere using these empirical methods..

So, yes the wave length will change, but just what might change it is far from clear, possibly a very active TS or hurricane that would act as a short wave between the one at 90W and the UK disturbing the current pattern as it moved through. All speculation of course but that could be what may change the current status quo, or rather the status quoas it will be from about day 4 onwards to beyond day 20 possibly unless the above happens?

So don't expect the Met O outlook for the 6-15 to change for a while yet and I can see why they suggest, apart from the POSSIBILITY of some settling down in the south early October why they persist with their below average temperatures, unsettled, windy at times in the NW and threat of both low minima in the quieter spells and possible snow over the highest upland areas in the north.

Edited September 16, 2012 by johnholmes

[ribster]

Ok C, back under my rock.

Not at all, if one looks only for synoptics/weather of a certain type, then they are likely to find it. For a more objective analysis, posts by Gibby, Frosty and John have made fantastic reading lately, giving a much clearer, unbiased view.

[IDO]

This morning the GFS has the much forecast trough hitting the far SE by late Monday (24th) and gone from there in 36 hours. HP before and after, giving average to above average temps (under the HP) down in the south. The north feels the effect of the trough for another 36 hours with associated lower temps and possibly more rain. However the trough is now being modelled as a transient feature rather than taking over. At the end of FI the Europe wide HP is sat over the UK. That is three GFS (0z &12z) runs in a row suggesting a HP scenario for late September onwards. The trend has definitely been going to a more settled setup and this scenario is now being modeled for further north in the UK.

Edited September 17, 2012 by i'm dreaming of...

[Gibby]

Good morning. Here is the latest report on the outlook from the models for this morning Monday September 17th 2012.

All models show a fairly benign pattern through the working week with A NW and somewhat showery airflow over the UK for the first few days before a ridge of High pressure affects all areas midweek. Later, a weak trough moves SE over Thursday bringing the potential for some rainfall followed by further High pressure on Friday when it should be dry and bright again for most.

GFS then shows next weekend as a deteriorating trend from the NW. Saturday will be fine and dry for many but through Sunday freshening SW winds courtesy of a depression to the NW slip down over the UK through the day with some rain following. The following week sees Low pressure in the North Sea for several days with wet and cool weather for many. Later in FI the trend is for things to dry out from the South with High pressure gradually developing near to and then over the UK by the end of the run with dry and bright weather developing for all.

The GFS Ensembles show a cool week to come before uppers return to normal values by next week. There is little rainfall for the South this week with a spell of wet weather next week before a trend to drier conditions occur again by the end of the run. Further North too average uppers look likely with rain at times throughout.

The Jet Stream currently streaming east over Britain takes up a more undulating pattern by next weekend and beyond troughing to the West and south of Britain by then.

UKMO for midnight on Sunday shows High pressure extending from Europe into the North Sea with Low pressure well developed to the West. A southerly flow develops with fronts approaching Western Britain later though through the day it looks from this pattern that most areas would stay dry. The East and South may become a little warmer through the day after a chilly start.

ECM shows a somewhat more progressive look with a trough to the west closer in on Sunday with rain likely here later in the day. The dry weather in the East on Sunday will be displaced for all by Monday and beyond by low pressure being fed down and over the UK from the NW with plenty of unsettled and sometimes wet and cool weather for all.

In Summary the weather still looks like turning unsettled and changeable from the NW later next weekend. It's progress has been repeatedly delayed of late leaving the interim period with rather quiet and unexciting weather with plenty of dry and bright if not overly warm conditions mixed with just a few showers or outbreaks of chiefly light rain at times. Night times look like being quite chilly at times this week with a risk of ground frost in places. Long term and the output does hint at a return to High pressure deep in FI with ECM too showing an embryonic sign of a more High pressure influence from the SW in the period after the end of the run.

Edited September 17, 2012 by Gibby

[Frosty.]

The further outlook is still looking very unsettled and cool but the week ahead is actually ok with all areas having sunny spells but with a scattering of showers but with chilly nights and even a risk of a touch of frost, the heaviest and most frequent showers tending to be across exposed northern and western coastal areas but occasional bands of showers spreading south and east to other areas, also a persistent area of rain midweek across central uk but just looking at the temps in the southeast, it will be feeling much cooler than recent times with 15 or 16c being the max on wed/thurs although some recovery in temps later in the week as high pressure spreads across the south and lasts into the weekend but further northwest it looks like low pressure will be moving in and the gfs 00z ens mean is showing low pressure dominant in FI with eventually a showery polar maritime airmass for all of the uk stretching out to at least T+300 hours. The Ecm 12z ens mean is also looking very unsettled in FI but with a high pressure cell before then across southern areas before we go deeper into a much more unsettled pattern but as it's FI, the eventual outcome may not be as bad.

[legritter]

I spent a considerable time about 8/10 days ago going through all charts and data and then putting together a forecast for about the 18/20th of September. This was just for personal reasons to see how using the forecast models etc would pan out - a total flop on my part. It now looks like any real change from the current setup will not take place untill around the 23/24th, with the possibility of some cold air being drawn south for a time with wet conditions for most and some chilly nights beyond this is definitely FI. I am looking foreward to the Met Office winter model as I've always said the key to future meteorological science could very well be in the upper atmosphere. Iinteresting times ahead for us weather fanatics.

Regards Legritter