Model Output Discussion 26/08/2012

[Methuselah]

Can if you want.

I haven't been told not to as long as its model based which it is, and provides an insight into what the models that many of us haven't got access too are suggesting.

Why do these folks make pronouncements, if not to encourage others' discussions? If they didn't want to be quoted they wouldn't make their views public, in the first place...

Edited September 21, 2012 by chionomaniac

[Gavin P]

Hi all,

Here's todays model based update video: Nadine And The Spawn Of Nadine: http://www.gavsweathervids.com

Models pretty clear on the general direction of traffic now (though JMA looks rather differant this morning) Just got to nail down the detail now - Won't be able to do that until tomorow 12z, probably.

Looking a nasty storm. We also need to keep an eye on what the actual remains of Hurricane Nadine itself does. GFS and ECM trending towards taking it towards Iberia and then moving it north...

Lots to keep an eye on for sure. :o

Edited September 21, 2012 by Gavin P

[chionomaniac]

I think that if you are providing details of a model such as the ECM 32 dayer second hand, then you should state where you are taking the information from (ie Matt Hugo) in future please, but otherwise that is fine.

There is an obvious difference between a meteorologist passing on information about a long range model that we do not have access to, and a television forecaster on television giving a forecast on information that we do have access to, ribster.

[AWD]

Yes, I should of done Chino, sorry. On previous such posts I always have done, I just forgot to do so with this particular post. Sorry for the confusion.

[shedhead]

Can I start quoting what Alex Deakin has been saying then (and not credit him with saying it), thought the idea was to post your own thoughts, not regurgitate what someone else has been saying.

Would be nice if you posted some thoughts at some point too ribster, rather than simply barating others.

[Frosty.]

I can see where the latest meto update idea of colder air and wintry showers in the far north through the extended outlook is coming from, the cmc ens mean shows this and the ecm ens is possibly trending that way but the gfs 06z ens mean is not, it's actually digging a trough southwards further west into the atlantic and the jet buckles as pressure rises to the south and southeast. I think the outlook trend is for the north and west of the uk to become generally unsettled and remain that way, this is also the case for southern britain for a time but probably drying up later as high pressure to the south of the uk eventually extends further north but the near future shows some welcome rain for the parched southeast, yes it really has been very dry in recent weeks with the problems returning but a lot of rain is likely to help that situation during the next week or so but it's the north and north west which are likely to be hardest hit by low pressure in the longer term.

Edited September 21, 2012 by Frosty039

[A Winter's Tale]

There's currently some rain and cloud cover associated with a weakening front over central parts of England towards the north sea. Through the rest of today, sunshine should continue over Ireland, Scotland and NW England and this should slowly spread into western parts of England and Wales and further inland as the front clears the south of England. There could be a few showers around the NE coast of Scotland through the rest of today. On the whole, a cold day overall with maximum temperatures in cities typically 11-15C.

Tonight should be dry for all of us and clear skies for the majority but as shown in the chart above a cold night is expected with lows of 4-8C in town and cities and lower than that in rural areas where in rural parts of highland Scotland we could minimum values around -2C early tomorrow morning. Subsequently, a frost should be likely for favourable places. Tomorrow morning should glorious for many of us with lovely morning sunshine and clear, blue skes - perhaps north sea coasts and parts of Cornwall could have some pockets of cloud however. The stunning, but cool weather should continue into the afternoon but there should be more clouds than in the morning in the sky on Saturday afternoon. Maximum temperatures at 11-15C. Saturday night again should be dry with lots of clear skies but north sea coasts of England and Ireland are expected to have an overcast night and some rain could be knocking on the door of the south coast. A cool night with lows of 5-10C in cities and closer to freezing in the highlands.

Sunday should see the best of the dry and sunny weather in Scotland and Northern Ireland whereas as the southern half of England and Wales are likely to have overcast skies with some unpleasant, wet conditions in the southern third of England associated with a front moving north and Ireland could be on the cloudy side with a weaker front in the area. The exact details on where the rain will fall is unclear so we have to wait till nearer to the time to find out. Maximum temperatures of 11-14C. The band of rain should move further NE across England on Sunday night and Ireland is expected to have some rainfall for a time from a weaker front. Away from the west coast, much of Scotland should have a dry and clear night. Not as cold as previous nights with lows of 8-10C.

On Monday, at the moment the scenario seems to be that heavy, persistent rain should affect the eastern half of England and extending further west with light scattered over western areas. The far south of England and Scotland at the moment are shown to be the driest and sunniest places but it's quite an unclear scenario at the moment so I expect details to change. Maximum temperatures of 11-14C. Monday night at the moment is shown to be largely overcast for all of us with persistent rain affecting NE England/SE Scotland extending westwards into parts of Ireland and some showers could be possible around coasts of the south. Minimum temperatures of 8-10C.

Tuesday looks like staying overcast with some light rain and showers around the coasts and Ireland and possibly some more heavier rain on the north sea coasts for a time. Maxima of 11-15C. And Tuesday night at the moment remains largely overcast with light rain and showers near the coasts with minimum temperatures of 8-11C.

The outlook beyond Tuesday suggests that a northerly airflow will develop on Wednesday and continue towards the start of the weekend as high pressure moves in from the west.

So in summary a cold, clear night tonight and a largely sunny and cool day tomorrow. Remains dry and sunny in the north on Sunday and Monday but uncertainty remains on a tricky area of low pressure moving from the south and details the following days are unclear but it's an unsettled scenario. Possibly a cold end to next week then high pressure may move in - beyond that is anyone's guess.

[legritter]

just from a personal perspective i just love it when you look on the fax charts and you see CORRECTION ,Its like the personal touch ,something special , fax 84 Hrs . will catch up with you all after tonights modell runs ,cheers

[Rainy]

A meandering jet stream forecasted again and some big temperature contrasts about. Southern parts of Greenland looking warmer than the UK early next week.

http://www.meteociel.com/modeles/ukmo2.php?nh=0&ech=12&carte=1021

Incidentally, what a waste having all that lovely warmth and settled weather over the mid Atlantic. If only ...

[Mapantz]

GFS 12Z keeps Nadine out in the Azores at T+132, quite a stark contrast to the 06Z.

[Zenarcher]

Both the GFS and UKMO 12z runs looks similar at 96 hours for the first time yet,

UKMO

GFS

Still seeing the models making some changes within the 48 hour range so things aren't completely certain yet but this is the first time the UKMO and GFS have agreed on something.

Edited September 21, 2012 by weathermaster

[Summer Sun]

Quite a nice start to October from GFS tonight

Certainly a lot more settled than what early next week is looking like

[chionomaniac]

Quite a nice start to October from GFS tonight

Certainly a lot more settled than what early next week is looking like

............and is FI and completely different to the last run............

(Therefore take with the proverbial pinch of salt)

[Summer Sun]

A quick look at early next week

Monday should be ok apart from Rain winds look fairly light for most the exception been north west Scotland and some eastern coasts

Later in the day its the same

Into Tuesday and most of mainland UK remains ok for the wind but it starts to whip up for the far north west and in the English channel

Later in the day winds remain light for all but the far north west and in the English channel

Into Wednesday and its the same still mainland uk remains with light winds whilst the far north west and the English channel stays windy

............and is FI and completely different to the last run............

(Therefore take with the proverbial pinch of salt)

I didn't see the 06z FI run so I don't know

Edited September 21, 2012 by Summer Sun

[I remember Atlantic 252]

Gavin, you can view 06Z on netweather data charts, click on 'prev run'

I usually look at the 18Z at around 8am, after the 00Z, just to see what it showed, cos im not up for 18Z at around 11.45pm

Edited September 21, 2012 by ihatetherain

[AWD]

We now know that the weather is going to turn increasingly unsettled as the weekend progresses, with some wet & windy weather for all on Monday & Tuesday before things turn more showery into Wednesday.

Lets see what the end of the week and next weekend currently look like though, see where we may be heading after next weeks unsettled weather.

The UKMO shows a northerly on its T144 chart, with showers anywhere in the UK, wintry over high ground in Scotland. Temps would stuggle to average at best in the south, elsewhere rather cool for the time of year.

The GFS still shows a shallow trough over the UK this time next week, but this quickly fills and high pressure nudges in from the South West bringing increasingly settled weather to the bulk of the UK, although the north of Scotland still prone to an Atlantic influence. Through FI and the GFS shows a rather slack, settled regime, although pressure does fall enough at times for showers to form in places. The Jet heads north over northern Scotland in FI.

Temperatures in FI could get quite warm for October too, until then the end of next week sees temps around average.

The GEM also shows a northerly this time next week similiar to the UKMO, with showers for most of the UK, wintery in the north on high ground.

[AWD]

Looks like some pretty good agreement now between the UKMO & ECM 12z output

JMA also looking more similiar to the above outputs than it has done recently

The GEM & GFS however have a shallower feature at the 72 hour timeframe, but do deepen it a little more in the next 24 hours afterwards.

[Zenarcher]

12z ECM Wind Speeds,

12pm Monday 30 to 40mph winds through the English channel and across Eastern Coasts,

6pm Monday still windy in the same places but the wind across Northern parts starts to increase,

6am Tuesday windy across most of the country with 35 to 45mph winds. North Eastern Scotland looks to get hit badly with 50mph wind speeds,

12pm Tuesday the wind eases in the North slightly but is still windy across much of the country, wind speeds ranging from 30 to 45mph.

After 12pm the wind gradually drops through the day. This evening we see most of the models starting to agree on this low although it's exact positioning and deepness is still yet to be figured out.

[Gibby]

Good evening. Here is a look at the 12zs from GFS, UKMO and ECM for tonight Friday September 21st 2012.

All models show a weak High pressure area over the UK tomorrow with light winds and fine weather for most. By Sunday Low pressure is developing over Biscay, deepening rapidly and moving NE towards Southern Britain. At the same time Low pressure is slipping down to the West of Scotland by Monday. The UK is then encompassed by deep low pressure with strong winds and a complex array of troughs delivering copious rainfall in many areas which lasts on until midweek. All three models illustrate this clearly tonight with GFS showing the least likelihood of disruption from wind (which is a switch from recently) while the Euro's (with the UKMO now on board) illustrating a potentially nasty period of weather for the South at least between Sunday afternoon and Tuesday.

GFS then shows the Low pressure filling up over Southern Britain to be replaced by a Westerly flow with further troughs moving East across Britain early in the weekend. Thereafter, the operational's FI output tonight trends towards warmer and more settled weather especially in the South for a while before things cool a little with some showery rain by the end of the run.

The GFS Ensembles show a wet week up and coming before things dry up somewhat. The operational was a warm outlier in the South at the end though uppers as an average to trend somewhat warmer for a while towards the end of the run.

The Jet Stream dives South to the West of Britain over the coming days before swinging NE across France and the Low Countries to start next week. Thereafter it is shown to maintain a position South of Britain albeit weakening with time.

UKMO at noon on Thursday has Low pressure stretching from Scandinavia to France with a cool Northerly flow over Britain. It would be very cool and showery with the air cold enough for some snow on Scottish mountains.

ECM shows the weather maintaining itself in a very changeable mode as we move into the later stages of next week. With winds often brisk and from a Westerly direction or a little North of West it will stay on the cool side. The trend though remains for a slow improvement in conditions temporarily as we move towards the end of the run.

In Summary the weather in the short term is less in agreement than the longer term pattern which looks like improving gently after a very wet week next week. In the short term it looks like a potentially nasty spell of weather is likely totally dependent on where the Sunday Low makes landfall and how deep it becomes. Each model update between now and Sunday is essential viewing for those interested in storm developments.

Edited September 21, 2012 by Gibby

[Summer Sun]

The BBC have a new video update for the stormy weather

http://www.bbc.co.uk/weather/features/19677758

[johnholmes]

Looking well ahead from the uncertainty this weekend to 6-15 days down the line?

The 500mb charts are certainly showing signs of change, gone is the meridional pattern being replaced, especially on the NOAA outputs by a much 'smoother' type pattern. A mostly W'ly flow over N America and near enough that over the Atlantic with a smooth sort of trough in the UK area. Its possible that a ridge may build again in the Atlantic as another +ve area of heights is being shown but not as pronounced as it was shown during the meridional phase.

We shall see of course in about a weeks time if this is the case, maybe the ridge bringing more settled weather into SW'ern areas especially?

Edited September 21, 2012 by johnholmes

[Cloud 10]

Looking well ahead from the uncertainty this weekend to 6-15 days down the line?

The 500mb charts are certainly showing signs of change, gone is the meridional pattern being replaced, especially on the NOAA outputs by a much 'smoother' type pattern. A mostly W'ly flow over N America and near enough that over the Atlantic with a smooth sort of trough in the UK area. Its possible that a ridge may build again in the Atlantic as another +ve area of heights is being shown but not as pronounced as it was shown during the meridional phase.

We shall see of course in about a weeks time if this is the case, maybe the ridge bringing more settled weather into SW'ern areas especially?

The 12z ECM ensemble mean for day 10 shows the pattern you describe,with the jet

running across scotland, so looks like a rain in the north drier in the south type pattern.

[ribster]

I think that if you are providing details of a model such as the ECM 32 dayer second hand, then you should state where you are taking the information from (ie Matt Hugo) in future please, but otherwise that is fine.

There is an obvious difference between a meteorologist passing on information about a long range model that we do not have access to, and a television forecaster on television giving a forecast on information that we do have access to, ribster.

Sorry, I thought Matt had his own website, posts on TWO, tweets etc, where his musings could be read, which if you have access to the internet (must do by being here), then you could access his musings, my bad!

[OldMetMan]

I've been watching the model output all week regarding the threatened intense LP for this weekend and I have to say that I do not recall any such development happening before.

Hurricane Nadine has been an enigma since it formed and i know that the National Hurricane Centre in Miami have really been struggling with it's behaviour and forecast all week. In particular, the track has been shown to vary greatly from model to model and run to run and at times, they have not even been sure what sort of beast Nadine is - is it still a tropical storm, a post-tropical depression?

Since Nadine arrived near the Azores, the models have, and continue to have a bewildering variety of solutions as to what to do with Nadine. What I find so intriguing is that, while ex-tropical storms do arrive on our shores from time to time, I cannot remember seeing a LP that has been apparently generated by such a storm. Even more puzzling is the way the models have been maintaining Nadine, even intensifying it in the days to come.

As far as the threatened storm here is concerned, yes there is certainly a large amount of very warm, moist air travelling NE towards the UK that apparently originates with Nadine, and that, together with the presence of the jet, could indeed be a situation to allow a rapidly deepening LP to form. The upper low to the W and NW is sharpening as the surface LP sinks SE. But in recent runs the models have had difficulty in deciding which LP will be dominant. The last 2 runs of the GFS have backed off quite considerably on the new LP's intensity but the ECM has gone quite mad and is showing a very intense system developing.

Meanwhile, the UK Met is sticking to it's guns, as it has for several days now, of developing the LP quite rapidly.

I find it unusual that there is so much model divergence so close to the time. I think it will be most informative in this situation to watch the satellite images very closely over the next 24 hours as LPs such as these have distinct signatures.Interesting few days ahead!

[AWD]

All models now have the low deepening over the UK on Moday bringing a spell of wet & windy weather over the UK before the low slowly fills over the west/south west of the UK, in turn turning more showery as the week progresses before a ridge of HP develops over southern parts inparticular. After that, as we enter FI, the models diverge more so.

Using the GFS 0z data, this suggests Wales could be the wettest place over the next 96 hours, with Scotland bearing the worst of the winds.