Model Output Discussion 01/09/17

[Man With Beard]

Bit of a standoff between GFS/ECM for next weekend - Saturday mild and dry for most seems set in stone but Sunday could be beach weather or a washout when comparing the two (fronts are already into the NW on both charts):

  

The ECM ensembles have been pretty solidly behind a very mild pattern for Sunday for some time - this morning's were no different. Would be a surprise if they are wrong.

[knocker]

This little upper trough that can be seen away to the south west at T120 is on the tail end of the front on which disturbances are occurring and the models are struggling to agree on the outcome over the weekend as they run north east on the slow moving front

[ANYWEATHER]

Evening All and the charts that's the gfs and ecm have watered down the late heat for late week into the weekend by a vast degree. Probably reaching 21c/70f somewhere across south east Britain, as things stand now . later in the ten day period both models show a volatile outlook.....

[Allseasons-Si]

I know it prob won't come off but the ECM day ten chart shows a nasty little low crossing the BI and on the southern flank we would expect some very windy weather

ouch!!!

but not one gefs ens supports this thank god,who will be right.

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=240

in fact looking at the ens,there is a lot going for hp over or near the BI,and just to add,the 6-10 and 8-14 500mb outlook from NOAA reflect this with troughs/lows not getting through to the uk,so a NW/SE split continues.

 

 

Edited October 8, 2017 by Allseasons-si
correcting

[ANYWEATHER]

58 minutes ago, Ice Man 85 said:

Looking at the end of the ECM 12z, if I'm reading it right, then we would see some pretty chilly uppers. Maybe the pain of this Indian Summer muck would be worth it after all.

Evening ! There is a weather term called in  Meteoroligy called Shannon Entropy . The Low Shannon entropy means the forecast in the ten day period is more certain . the High Shannon Entropy" which we are in now" means the outlook in the next ten day period is very uncertain...hope this helps..!

Edited October 8, 2017 by ANYWEATHER

[Allseasons-Si]

Temps coming down!!!

after a brief warm up at the end of the week and into the weekend,will we see things cooling off

London ens not so bullish

[knocker]

There are some major difference between last night's GEFS and EPS in the later period  anomalies so just sticking to the earlier period for a brief run through.

They all agree on a low over northern Canada with trough Greenland to the NW Atlantic, ridging to the south east of the UK and also into the eastern Arctic (this may well be influencing the GFS as it strongly links this with strong ridging close to the UK in the later period). Thus, depending on just how the trough and ridge are orientated we are looking at an upper flow tending south of west and as Allseasons has already mentioned a NW/SE split with temps a little above average.

Today generally cloudy everywhere but more so in western areas where there will also be outbreaks of drizzle whilst in the east there may even be sunny periods. later in the day more general rain will reach n. Ireland and then Scotland Once this overnight rain has cleared tomorrow will be bright and breezy for most apart from the south east where the sporadic rain still lingers

But by Weds 00 the next deep Atlantic low has swung north east to be 967mb SE Iceland with the associated fronts already impacting N. Ireland and western Scotland accompanied by some heavy rain and strong winds and more general rain as they slide south east during the day. Brief ridging on Thursday before the amplification, which has been mentioned ad nauseam, gets going with the next deep Atlantic low drifting north to SW Iceland and the very long associated front stretches a long way to the SW as the trough extends south.

Over the next 24 hours disturbances run along the front as it battles to track  east against the HP and it eventually dissipates but the next wave is more active and by 12 Sunday there is a shallow low over Scotland which deepens rapidly all of which facilitates the front to track across the UK into the North Sea. Thus rain for all areas on Sunday before the Azores ridges in the south west Monday. One thing that is noticeable with this analysis is the marked temp difference between the North and south on Saturday. !8-20C in England and Wales against 10-12C N. Ireland and Scotland.

The aforementioned ridge is short lived as the Atlantic batters down the resistance but best left here as this getting too far ahead considering the very mobile pattern

[knocker]

You really couldn't make some of this up. The ecm more or less agrees with the gfs over the weekend, albeit it has the front and wave a tad further west before the front dissipates as it crosses the UK on Sunday.  But it develops a much more active low on the tail of the front which tracks NNE to be an intense feature south west of Cornwall by Tuesday 00. It then sweeps it NE across Wales and N. England in the next 12 hours accompanied by heavy rain and strong winds in the west. It then quickly clear away before the next band of heavy rain arrives in the west by 00.

I humbly suggest that for the moment the detail for the weekend and later goes in the pending file.

Edited October 9, 2017 by knocker

[Summer Sun]

ECM shows the peak of the temps between Saturday and Monday

After this temps slowly return down towards average

[knocker]

I didn't twig earlier but this is what the ecm is playing with and developing as an extra tropical feature. We shall see

[Man With Beard]

2 hours ago, knocker said:

I didn't twig earlier but this is what the ecm is playing with and developing as an extra tropical feature. We shall see

Rather on its own then!
For what it's worth, for next Sunday the ECM shows the majority of English getting to 20C or above with long sunny spells, and well into the teens in other areas. Rain affecting far western coasts from Wales northwards, and a bit more drizzly in the far SW.

[MattTarrant]

24 minutes ago, Man With Beard said:

Rather on its own then!
For what it's worth, for next Sunday the ECM shows the majority of English getting to 20C or above with long sunny spells, and well into the teens in other areas. Rain affecting far western coasts from Wales northwards, and a bit more drizzly in the far SW.

The ECM may be predominately on its own, however it had a similar run last night (A day later of arrival).This area has to be watched carefully as it would be a seriously nasty period of weather. The GFS has the now classed tropical depression stalling out in the eastern Atlantic. The NHC Forecast Discussion on this was somewhat of a middle ground, with an expected east to north east track after a period of circulating around a similar area. So very uncertain track, needs to be kept an eye on.

[LightningLover]

18 hours ago, Allseasons-si said:

Temps coming down!!!

after a brief warm up at the end of the week and into the weekend,will we see things cooling off

London ens not so bullish

It's a start!

[I remember Atlantic 252]

More interest to me, Indian summer!

[BlueHedgehog074]

3 minutes ago, I remember Atlantic 252 said:

More interest to me, Indian summer!

Blimey! Such a marked contrast between Scotland and Central England! (lol)

[knocker]

The gfs takes the wave 984mb just north of Scotland on Sunday as the front prepares to sweep across the country whilst the HP to the south blocks any thought of northward movement of 91.

Obviously just theoretical at the moment but this volatile pattern could well throw up some severe gales.

Edited October 9, 2017 by knocker

[Dorsetbred]

47 minutes ago, knocker said:

The gfs takes the wave 984mb just north of Scotland on Sunday as the front prepares to sweep across the country whilst the HP to the south blocks any thought of northward movement of 91.

Obviously just theoretical at the moment but this volatile pattern could well throw up some severe gales.

It'll be interesting how deep Ophelia goes before she head our way. Looks like an interesting week next week.

 

Edited October 9, 2017 by Dorsetbred

[Polar Maritime]

Yes the GFS really wakes up the Atlantic into Wk2, With a very strong jet over the UK.

[LightningLover]

25 minutes ago, Polar Maritime said:

Yes the GFS really wakes up the Atlantic into Wk2, With a very strong jet over the UK.

That IS strong!

[knocker]

On a closer time scale the ecm has some very nasty weather overnight and into Weds, for Scotland, N.Ireland and northern England with heavy rain and gales, perhaps severe. Flash forward to 00 Sunday and the wave is west of N. Ireland and Ophelia is tracking east just south  of the Azores who could receive some very inclement weather from this and the front.

The wave continues on it's journey NE as the front loses it's identity over the western half of the Britain on Sunday as the rest of England basks in temps up to 23C in places. Meanwhile Orphelia is starting to swing NNE and is an intense little feature in the southern Irish Sea by 18 Tuesday. en route to the borders. Needless to say this scenario would drag some rain and warm temps with it.

That's just one theory of course.

Edited October 9, 2017 by knocker

[Ice Man 85]

2 minutes ago, knocker said:

On a closer time scale the ecm has some very nasty weather overnight and into Weds, for Scotland, N.Ireland and northern England with heavy rain and gales, perhaps severe. Flash forward to 00 Sunday and the wave is west of N. Ireland and Ophelia is tracking east just south  of the Azores who could receive some very inclement weather from this and the front.

The wave continues on it's journey NE as the front loses it's identity over the western half of the Britain on Sunday as the rest of England basks in temps up to 23C in places. Meanwhile Orphelia is starting to swing NNE and is an intense little feature in the southern Irish Sea by 18 Tuesday. en route to the borders. Needless to say this scenario would drag some rain and warm temps with it.

That's just one theory of course.

Yep, looks like the little swine is trying for a redux on Tuesday.

[Allseasons-Si]

The ECM day ten chart shows high pressure punching up into the southern tip of Svalbard,maybe watch the back door for an easterly to set up from there

the black arrow showing WAA and the red arrow pos producing an easterly

the latest 8-14 dayer 500mb outlook from NOAA shows this hp in that area too.

[ANYWEATHER]

Hello All! The Gfs and Ecm output is nothing more than the "WOW" Factor , with heat ,storms and cold. Lots to iron out , but after the short burst of heat , a wind storm, then turning cold , who could make this up !

[ANYWEATHER]

And the T+240 at the ten day range from both gfs and ecm show us some cold weather....

[knocker]

A quick look at the anomalies this evening merely confirms what we already suspect and that is unsettled continuing to be the percentage play for the medium term outlook, with the vortex lobe and trough to the NW and ridging to the south east being the major players. There is some differences between the orientation of the GEFS and EPS vis the trough and ridge bur essentially we are looking at a flow south of west probably portending a bias towards a N/S split and temps a shade above average,Of course a TS could cause a brief hiatus if it sticks it's oar in. In the later period no significant change with perhaps the trough taking closer order. and temps reverting to normal

And just out of interest a pretty solid pattern through to the lower Strat

 

Edited October 9, 2017 by knocker