Model Output Discussion 06Z, 13 Sep. 2013 ---->

[BlueHedgehog074]

Some potion bottles which could be useful during the Winter/late-Autumn period where the Model Output thread could start becoming a bit hectic...

 

 

Also, just briefly looking at the models such as the latest GFS, UKMO and ECMWF, there seems to a chance for areas to start settling down (especially for the South), mostly for late next week as Pressure from the South attempts to rise up and fight away some of the powerful Lows shown on the models. I do, perhaps, suspect the GFS 12Z has probably overdone the intensity of that storm that tries to scrape past to the North-West of the UK...

 

 

Either, the GFS will continue its (probably) unlikely evolution of this intense Low, or either start dropping its 'storm' idea considering the general lack of support from other models (except the GEM, which has it trying to go through the North of the UK).

[Frosty.]

The GEFS 12z mean shows the azores anticyclone building a strong ridge northwards through the uk by T+120 hours (friday) and the high then strengthens through the weekend and into the beginning of the following week, so there is currently a good chance that next weekend will be fine and sunny with temps into the low 20's celsius, perhaps nearer to 23-25c for the south/se next sunday and the following monday, beyond that, the mean shows a trend towards less settled and less warm weather but nothing dramatic, the weather pattern ends up looking pretty benign with light winds and average temperatures with sunny spells and a risk of showers but with light winds and where skies clear overnight, especially after late showers, there would be problems with fog through the morning rush hour, so things are looking good from later this week, it's unclear how long the fine spell would last but let's just enjoy whatever we get, it's a bonus.

[Summer Sun]

Pressure still on course to rise for the weekend from ECM

 

 

GFS still overcooking Humberto by miles this evening

 

Edited September 15, 2013 by Summer Sun

[Captain Shortwave]

Pretty similar run to this morning from the ECM until day 8 where it starts to form an elongated high. 

Edited September 15, 2013 by Captain shortwave

[Cheshire Freeze]

Pretty similar run to this morning from the ECM until day 8 where it starts to form an elongated high. 

 

The 192 hrs chart is a dead ringer for the 144 hrs UKMO chart in terms of that HP.

[Summer Sun]

t192 similar to UKMO at t144 as CC has said +10 uppers across the UK

 

 

t216 remains settled and warm by day chilly at night, low pressure back over Greenland

 

 

Edited September 15, 2013 by Summer Sun

[Cheshire Freeze]

ECM 216 hrs..... calm, warm by day and chilly by night

 

[Summer Sun]

The high stays in control at t240

 

 

Staying warm by day and chilly by night

 

Backs up the thoughts of the beeb's week ahead forecast as well hinting at warmer weather next week

 

Don't throw your t-shirts away yet there are signs it could turn warmer next week

 

Edited September 15, 2013 by Summer Sun

[Captain Shortwave]

ECM 216 hrs..... calm, warm by day and chilly by night

 

That trough over Russia is just too close to us to allow the southerly flood gates to open. Still would be very good for late September if you like pleasant sunny weather.

Day 10 - High pressure in total control,

 

normal caution applies here

[ANYWEATHER]

ECM 216 hrs..... calm, warm by day and chilly by night

 

You have to remember that nothing is set in stone , the tropical/ex hurricane storms will play havoc with northern Hemispheric pressure, just look at in Ingrid and Manuel,,,,,  Lets ride that rollercoaster,,,,,,,  

Edited September 15, 2013 by ANYWEATHER

[Gaz1985]

Very pleasant if this came off  

 

[bluearmy]

not another split flow scenario !!!

[Man With Beard]

That trough over Russia is just too close to us to allow the southerly flood gates to open. Still would be very good for late September if you like pleasant sunny weather.

Day 10 - High pressure in total control,

 

normal caution applies here

well the hurricane could turn into Indian summer's friend in the end, pushing right through the west of Ireland up into the Arctic, smashing the heights there for the time being and allowing heights to push up to us from the south

I'm guessing with the ECM scenario that we may see 22C-25C in the south by next Sunday/Monday but then as the high gets on top of us the temperatures will drop a degree each day and fog will linger increasingly into the morning - unless a good southerly drift can get established

[damianslaw]

Near timeframe - i.e. out to Thursday, its very much an autumnal picture and chilly to boot with strong winds and showers - the type of outlook which every other year usually shows its hands just after the equinox - so a little earlier than normal.

 

However, as we approach the equinox the models are suggesting a back flip to late summer conditions thanks to the projected path of ex hurricane humberto which will prop up ridge development from the azores and pull in much warmer uppers off the continent.

 

September very much yo-yos between summer and autumn and often tests the patience of those wanting the new season to start proper.

 

I remain cautious in terms of the longer range outlook, we have seen a powerful jet appear in recent days and whilst it does look likely we will settle down by next weekend with ridge development - I am certainly not banking on a sustained warm dry settled spell seeing the month out - watch energy quickly resurge to our NW which at this time of year can easily shift any heights sat over or to the east of us into touch - the temperature gradients in and around the SW of Greenland increase rapidly at this time of year - don't be surprised if a split ridge pattern develops again with the trough finding its home directly over us again...

[Yarmy]

To my eyes, it looks like there is something for everyone in the current output. A decent (presumably) last shot of Summer and at the weekend too. Meanwhile into the week after a mass of cold pools over Russia preparing to deliver us something when it actually means something...

 

 

21c or 25c? Who cares, I'm going to the beach on Sunday.

Edited September 15, 2013 by Yarmy

[Summer Sun]

Latest from Gibby on the models

 

Good evening. Just rescuing this thread from the very rare event of it nearly falling off of page 1 of the forum here is the evening model report taken from the 12 noon output from GFS, UKMO, GEM, NAVGEM and ECM for today Sunday September 15th 2013.

 

All models show High pressure returning to the British Isles tonight. Before that happens though we have to get rid of the current deep depression close to Northern Scotland first as it transfers slowly SE and fills through the week. Further wave depressions look like crossing the South on Tuesday and troughs most places on Thursday with Wednesday being somewhat showery while Friday becomes more generally dry as pressure builds up from the South with sunny spells and cool nights.

 

GFS shows next weekend as a warm and fine one as High pressure builds across all of the UK and with winds inherently having blown up from the SW it will be warm by day but with some mist and fog night and morning. The latter half of the run shows fine weather largely persisting across many parts but things will slowly cool down day by day to become somewhat chilly by the end of the run with some mist and fog night and morning throughout and the chance of a ground frost late in the run.

 

The GFS Ensembles show the operational was a warm outlier in part 2 of the run and was not very representative of a rather changeable rest of the pack. Rainfall amounts look close to average for the most part though many areas look like having a drier interlude coinciding with next weekend.

 

The Jet Stream tonight shows the flow continuing to flow SE across the UK as further troughs and disturbances come through the UK over the next few days. It then ridges north of the UK in response to the drier period next weekend before it settles in a West to East flow across the Atlantic and Scotland through Week 2.

 

UKMO has High pressure elongated across the UK from a centre over Northern Norway. The weather would be dry and bright with some sunshine and daytime temperatures close to average but cool nights with mist and fog.

 

GEM is a little more reluctant and less extensive in its spread of High pressure across the UK next weekend. Nevertheless the South at least would see some decent weather with any rain and attendant cloud restricted more towards the North and west at first and towards the SW in the far end of the run.

 

NAVGEM has High pressure developing over the top of the UK next weekend and lasting into the following week. The weather would settle down with sunny spells and light winds by day when it will feel quite warm but cool nights with mist and fog problematical night and morning.

 

ECM shows quiet Autumnal weather developing from early next weekend with a light westerly breeze at first before High pressure builds over the UK with fine and quiet days with some sunshine but cool and misty nights with dense fog in places, slow to clear in the mornings.

 

In Summary the trend towards High pressure building back over the UK shown in previous output of late has gathered pace tonight with all areas looking like settling down next weekend at least for a time as High pressure builds across the UK from centres to the SW and NE. Though some warm uppers are shown by some output others show cooler conditions with all models that show High pressure over Britain next week likely to bring mist and fog problems overnight as well as making it feel chilly in the morning's.

 

http://www.norton-radstockweather.co.uk/Model-Analysis%282859336%29.htm

[Frosty.]

The Ecm 12z operational run has really produced something very special here, this turns into a stunning run with anticyclonic conditions tightening it's grip even by T+240 hours, there are a few incredible looking charts here, between T+168 & 192 hours with the 564 dam line well into the uk, these are mid summer charts near the end of september, it's incredible, if ever I wanted an ecm run to verify when there is still the potential for a very warm settled outlook, this is definately it, what an amazing transformation from what this model was showing only a few days ago, let's hope this trend is locked and loaded.

[BlueHedgehog074]

Near timeframe - i.e. out to Thursday, its very much an autumnal picture and chilly to boot with strong winds and showers - the type of outlook which every other year usually shows its hands just after the equinox - so a little earlier than normal.

 

However, as we approach the equinox the models are suggesting a back flip to late summer conditions thanks to the projected path of ex hurricane humberto which will prop up ridge development from the azores and pull in much warmer uppers off the continent.

 

September very much yo-yos between summer and autumn and often tests the patience of those wanting the new season to start proper.

 

I remain cautious in terms of the longer range outlook, we have seen a powerful jet appear in recent days and whilst it does look likely we will settle down by next weekend with ridge development - I am certainly not banking on a sustained warm dry settled spell seeing the month out - watch energy quickly resurge to our NW which at this time of year can easily shift any heights sat over or to the east of us into touch - the temperature gradients in and around the SW of Greenland increase rapidly at this time of year - don't be surprised if a split ridge pattern develops again with the trough finding its home directly over us again...

I think that's a good point to be fair since their is quite a bit of doubt about how long any possible ridging from the High Pressure to our South/South-West for next weekend can last over the UK. It could go the way of the generally High Pressure dominated outlook in FI of both the GFS and ECMWF 12Z runs (and maybe the UKMO if it went out further), although clearly more runs would be needed to see whether those models are trending in the right way. Plus, the 00z ECMWF Pressure ensemble mean doesn't look entirely encouraging for something High Pressure dominated to sustain itself, particularly for the North, so you could be right that the High Pressure could get knocked away easily. (Especially as you say, the energy/Lows to the North-West could put it under threat).

Edited September 15, 2013 by DiagonalRedLine

[William of Walworth]

I take damianslaw's and Diagonal's points for sure, but another possible evolution would be more in the way of a N/S divide, or at least NW/SE divide (position of dividing line : anyone's guess!).

 

Anything can happen that far out.

[snowking]

As has already been commented upon this evening we really do have a very complex situation coming up with Humberto causing some headaches, not only on its track and intensity, but also with the fusion of energy as it interacts with the Jet. Therefore, it really is wise to give things another 48-72 hours before making any judgement.

What I would say is that for some time now (since March, in fact) my own composites have pointed towards October being a rather HP dominated month - and so as we edge closer to October my expectation is for high pressure to start taking charge of the outlook. At present we are still, other than the likelihood of a temporary ridge next weekend, chasing charts out at days 9 and 10 for anything extensively settled, and indeed that has been the case now for some days, but I feel that within the next week or so we should begin to reel this signal back in once again.

We have spoken previously about seasonal wavelength changes, but as we start to lose the tropical forcing once again it will be interesting to see whether we maintain the same background signal - I.E ridging - as we have seen in recent months.

SK

[johnholmes]

Picking up on the comments about model variability perhaps due to Humberto, this is the picture from the now 3 main models at T+120, that is next Friday. Remember this count down for then began at T+192.

GFS continues on its own in how it deals with Humberto.

 

Humberto for next Friday on Sat and Sun previously.pdf

 

the latest T+120 Fax=Friday 12z has no marked sign of ex Humberto other than a surface trough and slack area shown south of 40N and west of 40W. This corresponds to Miami sea forecast suggesting a centre about that area?

Edited September 15, 2013 by johnholmes

[Captain Shortwave]

Humberto's movement on this run is quite a bit slower, though the effect on the UK isn't very much at all

 

Compared to the previous run 

 

UKMO for the same time

Not far off the UKMO's placement at this point

This aside, the pub run looks like it could turn out pretty special here

 

This could potentially result in a southerly flow if the high continues to drift north east.

Great potential with uppers of 12C across the whole of the UK

Edited September 15, 2013 by Captain shortwave

[Gaz1985]

Friday looking good for the pressure increase..

 

 

Saturday more pressure.. 

 

 

 

Sunday too, fantastic GFS run, possibly a great weekend coming up with strong high pressure  

 

[Duncan McAlister]

If you look now at around +216, the 12z and 18z are virtually identical. Not often you see that at that range.

Edited September 15, 2013 by Duncan McAlister

[mushymanrob]

Yes but we also have to remember we'll be nearing the end of September by this point. Any HP over us will result in a rapidly cooling ground level and thus any warm uppers (such as shown) will result in mist and fog forming overnight. Temperatures would probably be supressed in some locations from the 21C shown as any mist and fog may be more stubborn to clear than it would have been a few weeks ago. There will be a crossover sometime in October where HP will mean cooler than average.

 

If it was a southerly flow shown (such as late Sept 2011) it'd be a different story

 

 

Please don't fall into the trap of putting too much emphasis on uppers during late September. They're much less relevant than they were a few weeks back. We'll be past the equinox by then with added implications of overnight mist/fog (depending on situation of HP). Will feel pleasant during the day in the sun though.

 

 

See my post above. I'm not rubbishing the potential for any warmth at all. However, given the time of year, there are many more variables to take into account when talking about potential max temperatures and weather at ground level etc. Come September 22nd the sun will be in the same position in the sky as it was on March 21st. You have to take these things into consideration.

 

very wise words mate.... viewing the runs before coming here you have already highlighted my concerns. these charts look fantastic for summer, but its not summer now (the weather so far this month highlights why september is autumn), and to see a nice big high sat over us does not automatically equate to sun and heat. im not clever enough to forecast the fog lifting to low cloud possibilities, but i do know that cool nights can bring troublesome fog. the exact centre/orientation of the expected anticyclone/displaced azored high will be crucial.

 

edit... im not suggesting though that we wont get some sun and warmth, that appears highly likely going off current model outputs.

 

interestingly the anomaly charts have started to suggest upper high dominance 6 - 10 day timeframe, lending support to the ops, IF subsequent runs support this.

Edited September 16, 2013 by mushymanrob