Model Output Discussion 31/07/14 onwards.

[lorenzo]

It's definitively not a summery outlook as the trough solution well advertised from some 6 days prior verifies and continues to be projected across the remainder of August. 

 

The runs are toying back and forth with a resurgent Azores ridge to the West of the UK, however this morning GFS in lala land blows this aside as depressions begin their Autumnal procession across the Atlantic. Summer dissolving into Autumn would be the sum up.

 

Found this post with some amazing info. on MJO and GWO and also an up and coming monster African wave that is projected for later in the month which would serve to mix things up a little. A good read, especially with respect to the influence on the strength of the Jets and what this does to early pooling Arctic air. http://www.wsi.com/blog/energy/sub-seasonal-u-s-temperature-outlook-for-september/

 

Would be ideal to get a phase of this out of the way and then head back to some later summer heat courtesy of some plume action in September. What also would be great is if this early GH solution decides to be the background pattern for the next few months, might kick off Winter in style if it decides to echo through Nov/Dec.

[Frosty.]

A real autumn chill heading to scotland next week, they bear the brunt of the cold blast straight from the Arctic, max temps of 11c but add in the wind chill factor and it could feel like 5 celsius, these charts from the Gfs 00z op run are about as cold as it can get in mid to late august up north, not cold enough for mountain snow yet but not far off either. A very chilly, windy and unsettled spell for northern uk next week, cool and unsettled further south but not as nasty as scotland endures, it may warm up a bit across the south later next week as a ridge of high pressure tries to build in but next week shows autumn baring it's teeth...ouch..for scotland this is gonna hurt 

 

As paul hudson the weatherman would say..nithering northerlies are on the way

Edited August 15, 2014 by Frosty.

[knocker]

Whilst the midnight ECM ops is by means as bullish as the GFS it has also swung into this Atlantic pattern by the BH. The anomaly chart has produced an intense upper low with a brief transient ridge just to the west of the UK.

 

Depression moving into the UK with temps way below average  But wait. Signs of a very brief plume on Monday? Calm down.

 

Await the ens.

 

Thanks for that link Lorenzo

Edited August 15, 2014 by knocker

[knocker]

The ens seems to have brought a little sanity into play regarding the Atlantic depressions and the ECM has, shall we say adjusted the 500 anomaly. Still way below average temps but the Azores ridge back into play. It's not obvious how this can play a significant role given the current set up and the position  of the jet.

 

 

[Frosty.]

If anything, the Ecm 00z ensemble mean has strengthened the view that the weather will be gradually warming up again by the end of next week with winds eventually switching from N'ly to SW'ly and with the azores anticyclone ridging into the south/se and lower heights to the northwest of the BI, the scandi trough slowly filling and drifting further away as time goes on. We end up with a nw / se split with the driest, sunniest and warmest spells across the south & east and on the other side of the coin, the northwest of the uk having less settled and less warm conditions.

 

As for next week, a significant autumnal edge to the weather with very cool Northerly winds feeding south from the cooling arctic, very cool and unsettled next week, especially so across the north and east, cold and windy across the far north with frequent blustery showers, showery but gradually less windy further south with temperatures well below average across scotland, at least north of the central belt and struggling to reach average even on the south coast.

[Blessed Weather]

According to the BBC1 weather forecast at lunchtime today there's every chance of some snow falling on the tops of the Scottish mountains next week. Output from this mornings GFS 06z certainly supports the Met Office's thoughts. Here's a chart showing the height of the 0c isotherm for next Thurs 21st (but note that there are similar charts from Mon right through to Thurs).

Virtually the whole of Scotland has the 0c isotherm height at 1,500 metres or approx. 4,500 feet. With Ben Nevis at 4,409 feet that's one mountain top that looks likely to turn white!

 

[Yarmy]

According to the BBC1 weather forecast at lunchtime today there's every chance of some snow falling on the tops of the Scottish mountains next week. Output from this mornings GFS 06z certainly supports the Met Office's thoughts. Here's a chart showing the height of the 0c isotherm for next Thurs 21st (but note that there are similar charts from Mon right through to Thurs).

Virtually the whole of Scotland has the 0c isotherm height at 1,500 metres or approx. 4,500 feet. With Ben Nevis at 4,409 feet that's one mountain top that looks likely to turn white!

 

http:////f1.nwstatic.co.uk/forum/public/style_images/tctc91_simplify/attachicon.gif0degisotherm GFS 06z for 21 Aug.jpg

 

Not to be a pedant, buuuuut 1500m is 4921 feet. Still, there's a chance. 

[Blessed Weather]

Not to be a pedant, buuuuut 1500m is 4921 feet. Still, there's a chance. 

 

Whoops! You're absolutely right Yarmy. I never was very good at maths!

I guess it might need the temperature to be pulled down temporarily during heavy showers!

[A.J]

my bad Yarmy, mis-read your post... your posts are restored back to the thread 

[Paul]

Whoops! You're absolutely right Yarmy. I never was very good at maths! :fool:I guess it might need the temperature to be pulled down temporarily during heavy showers!

Bear in mind that the snow line can be 200-300m below the 0c isotherm.

[damianslaw]

Very quiet in here today - must be because the models are showing the same thing they were yesterday - i.e. a very disappointing one for the time of year and distinctly autumnal in flavour with suppressed temperatures especially so in Scotland.

 

Any change to something warmer and settled looks like being a very slow affair and not in time for at least the start of the Bank Holiday.

[Frosty.]

Brrr the Gfs 12z op run shows increasingly cool days next week with lots of showers and cold nights with grass/ground frosts and even a risk of slight air frost later in the week. This will be a very unusual occurance for august to have some of the white stuff, I also reckon there is a chance of august snow high up in the scottish mountains before the end of next week..roll on winter, I hope the weather remembers to repeat this during winter.

[Man With Beard]

The theme tonight is very consistent with previous days - a fairly static pattern with low pressure never far from Scandi - until at least D8, when an Atlantic trough may be favoured. NOAA charts tonight backing that idea:

www.cpc.ncep.noaa.gov/products/predictions/814day/500mb.php

however no sign of a long lasting pressure rise, so any ridge that does build may be transient and, since the summer warmth has been pushed a long way south, the ridge may not be sufficient to lift temperatures that much - to do that, we'd need a stable southerly flow for at least 3 days I reckon - possible, but the outside bet ATM. Every chance then that the rest of August will stay average or below, with 25C not being reached again, and rain never being too far away.

[ANYWEATHER]

Very cool air descending over the uk from the weekend onwards, along with changeable to unsettled conditions. I think there well may be some record lows over the Uk for both night and day next week , for this time of year given the persistence of the synoptic charts! Both ecm and gfs show by next week show  the potential for a shortwave development by mid week. After that the bank holiday weather is still uncertain, although models indicate a brief ridge then low pressure in control.....Also ,plenty of opportunity for snow to fall over the highest mountains in Scotland, that indeed is fairly unusual.......Given the time of year. 

Edited August 15, 2014 by ANYWEATHER

[Summer Sun]

ECM offers some hope once again towards the BH weekend

 

 

 

However if a settled spell did develop its not shown to last BH Monday sees low pressure sweeping back in with it, it brings some warmer air

 

[Frosty.]

The GEFS 12z mean shows the pattern becoming flatter once next week's potent scandi trough weakens and then gets shunted away by a building azores ridge towards the south of the uk, so it should begin to warm up from the end of next week onwards with some settled weather, especially across the south but occasionally more unsettled, however, with winds generally south of west beyond next week, all parts of the uk are likely to see temperatures returning to where they should be in the 2nd half of august, the south / se having a good chance of some very warm and sunny days towards the end of the month into early september but the northwest of the uk probably more unsettled overall.

 

For next week the max temperatures will be a good 3-6 celsius below average which will be a shock to the system following such a warm summer ( June & July) It will probably feel more like late september / early october by the middle of next week.. August CET is currently 0.3 c above average but that is going to change.

[Nouska]

Brrr the Gfs 12z op run shows increasingly cool days next week with lots of showers and cold nights with grass/ground frosts and even a risk of slight air frost later in the week. This will be a very unusual occurance for august to have some of the white stuff, I also reckon there is a chance of august snow high up in the scottish mountains before the end of next week..roll on winter, I hope the weather remembers to repeat this during winter.

 

I was just looking back through my records for the last time we failed to reach 20c on an August day - 2010. A scan of the archives located this chart - not a million miles away from what is forecast next week. That was quite a nice memory recall in December of that year.

 

http://www.meteociel.fr/modeles/archives/archives.php?mode=0&month=8&day=24&year=2010&map=0&hour=12

[SMU]

Evening All-

 

A decidedly cool week with a polar air mass visiting our shores, fairly potent for August-

 

http://modeles.meteociel.fr/modeles/gfs/runs/2014081512/gfs-6-102.png?12

 

unusual to see the 0c isotherm visiting the UK mid august ( Some 8c below the average )

 

http://www.wetterzentrale.de/pics/Rmgfs932.gif

 

An early season mention of frost for Northern Areas- mainly Scotland.

 

Summer is over in 15 days so we are now in the final throws & its been pretty good here, however as we descend into Autumn thoughts turn to the winter ahead .....

[Summer Sun]

Obviously these change with ever run but the 2m temperature anomalies from the 12z show the UK well below normal for the next 8 days

 

[draztik]

Ecm ensembles show a moderation in temperature as we head post day 10, but nothing to write home about and no last hurrah as we head into September. In the 5-10 day space, its the trough to our NE dictating our conditions. So well below average, then a return to average. Though, it doesn't look all that settled into days 10-15, with the ens indicating the presence of another trough over the UK.

Days 5-10 height anom & temp anom.

Days 10-15 height anom & temp anom.

Edited August 15, 2014 by draztik

[lorenzo]

Sincerely hope respect is paid to the ECM Ens this Winter having read them being rubbished a whole lot last season, where in fact they performed as well if not better than 12/13, just served us some ugly, ugly predictions which meant last Winter was a big old grind..

 

Beginning to wonder at what date this trough solution will hint at change considering the 'inevitability' of the next 12 days or so, African wave minus the Saharan suppression of TD and TC formation may lead to some Hurricane interest before end of August and re-shuffle the deck.

 

For real early 'tea leaves' forecasting on Winter one thing that is visible just now simply through a few years of watching is the disruption of systems, this year Greenland seems to be the area for trough disruption already, whereas we were well beyond this position last season with depressions progressing readily and easily to Iceland before breakdown and change to pattern, fuelling troughs. This is thinking our loud and theoretical and October is the pivotal read on where the trend lies, still an early obs that hopefully bodes well..

[knocker]

Sincerely hope respect is paid to the ECM Ens this Winter having read them being rubbished a whole lot last season, where in fact they performed as well if not better than 12/13, just served us some ugly, ugly predictions which meant last Winter was a big old grind..

 

Beginning to wonder at what date this trough solution will hint at change considering the 'inevitability' of the next 12 days or so, African wave minus the Saharan suppression of TD and TC formation may lead to some Hurricane interest before end of August and re-shuffle the deck.

 

For real early 'tea leaves' forecasting on Winter one thing that is visible just now simply through a few years of watching is the disruption of systems, this year Greenland seems to be the area for trough disruption already, whereas we were well beyond this position last season with depressions progressing readily and easily to Iceland before breakdown and change to pattern, fuelling troughs. This is thinking our loud and theoretical and October is the pivotal read on where the trend lies, still an early obs that hopefully bodes well..

 

I wonder about that.

 

Dry Air Dominates the Atlantic

 

There are two tropical waves in the Eastern Atlantic worth mentioning today--one right at the coast of Africa, and another about 700 miles to its west, a few hundred miles southwest of the Cape Verde Islands. Both of these waves are headed west-northwest towards much drier air, and none of the reliable models for tropical cyclone formation is predicting development during the coming five days--though the wave farther from the coast of Africa has the UKMET model and a few members of the GFS and European model ensembles showing some weak development. In their 8 am EDT Friday Tropical Weather Outlook, NHC gave the disturbance near the coast of Africa 2-day and 5-day odds of development of 0% and 20%, respectively. Dry air dominates the tropical Atlantic, and it will be difficult for a tropical storm to form in the coming week.

 

http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2761

[knocker]

A quick look at the ECM ops for 00 Tuesday. Thank heaven it's not winter.

 

[IDO]

All models are aligned for the coming week. There is a cool upper flow, with the 4c isotherm failing to return north of Birmingham till around D8, and reaching the south coast for a time. The wind is from the N/NE for the coming 6 days so feeling cooler than the actual temp, with the south having highs of 3-4c below the last week and 8-10c below the late July/early August highs. No washout for the south with the north fearing worse for the next 8 days:

 

 

The GFS op this morning moderates the potential rise in pressure around D7, so again next Friday-Saturday probably similar to this. A brief lull before a return to more unsettled:

 

 

This time it will be from the west so uppers will recover and feeling warmer between the rain bands.

 

Out into FI it appears that we have an oscillating pattern of short wave transient ridging and troughing so for the south at least some nice days thrown into the mix:

 

 

 

The feint hope in some of the ensembles for a more sustained pressure rise by around D8 has gone this morning with the D10 mean offering little hope of a return to settled weather:

 

ECM mean from last night offering much the same: 

 

GEM offers a similar week 2 pattern with a transient ridge followed by a westerly flow though it is has slowed the flow; allowing a more settled weekend but the following low is deeper and slower:

 

 

GEM probably overdoing it again. 

 

 

Further out into September and the JMA monthly suggests a westerly flow, so probably mixed, with as a whole, surface pressure just below average for the UK:

 

 

It now looks like we have seen the last of Summery weather in Summer. Signs from the LR at the moment suggests September won't be too bad though no signal for an Indian Summer at the moment.

Edited August 16, 2014 by i'm dreaming of...

[bluearmy]

Just as we saw the modelled less settled weather being shortened and in some cases not occurring at all through June and July, so the pendulum has swung the other way and we now seem to be in a period where the promise of higher heights is one that fails to materialise or is very transient. strange to say that summer is over, but given how good it was for large parts of June and July, methinks that's pretty well it for warmth this season, apart from the odd day of two. it doesn't look like there is a chance of a flip back. anyone care to make a call on what changed! Was it really just down to the energy in Bertha being able to get the mean lw trough to our east? Surely not.