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


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Good morning folks. Here is the daily morning look at the midnight outputs issued by GFS, UKMO, GEM, NAVGEM and ECM for today Wednesday September 25th 2013.

 

All models indicate a warm South or SE feed across the UK between Low pressure down to the SW and High to the East. This pattern changes little over the coming days with a trend for Low pressure to edge closer to Southern Britain by and over the weekend with a stronger risk of rain at times than is shown currently. The North on the other hand will see the current occasional rain slip a little further South with much cooler conditions for a time before milder SE winds push back North later with just a little rain more likely in the West of this area.

 

GFS then shows a changeable pattern next week as Low pressure slowly migrates North and East to the West of the UK turning winds from the SE towards a Westerly point. Through this period all areas are still at risk of some rain but Eastern and NE areas may not fair badly with a lot of dry and still reasonably warm weather to be found. With the Low to the SW moved NE it opens the door for the Azores High to build again across Britain for the countless number of times over the last three or four months which would return fine and dry conditions for most with reasonable day temperatures but mist and foggy nights likely again too. Any cloud and rain would then become restricted to the far NW of Britain.

 

UKMO today shows an undercutting development with energy from Low pressure to the SW sliding East across France keeping Southern Britain at risk to rain at times, some of which would be heavy as fronts edge North. The North would become or stay largely dry as High pressure out to the East extends a ridge West towards Scotland with all areas experiencing winds from an Easterly point.

 

GEM today shows High pressure over Scandiavia towards midweek next week while Low pressure out to the West and SW continues to spin troughs up across the South and West of the UK. Rain at times would occur here with misty conditions in often leaden skies. Further north and East conditions will be drier but here too a lot of cloud and a little rain is possible at times. Fresher cleaner air could reach the SW at the end of the run as winds begin to turn towards the SW.

 

NAVGEM shows High pressure slipping South over Europe next week with the persitent Atlantic Low pressure to the West filling and moving slowly North. The net result would be for winds to turn from SE to SW with time with the occasional rain in the South and West transferring more towards the NW while Southern and Eastern areas could potentially become dry and warmer again later next week.

 

ECM is broadly similar as it too has Low pressure filling and moving NE to the West of the UK while High pressure over Europe extends a finger towards Southern Britain with a warm SW flow developing with the rain of early in the week in the South and West extending North to the NW but leaving the South and East relatively dry and possibly bright by the end of the week.

 

The GFS Ensembles show that warm weather is expected to persist over the Uk for the coming two weeks. A slow leak of warmth is shown over the period but even by the end of the run there is good support for a maintained spell of uppers above average. Rainfall amounts are showing a continued trend to lessen in amount from previous outputs especially later in the run and in the SE.

 

The Jet Stream shows the flow developing to the South of the UK over France for the next three to four days before this pattern weakens as a new arm now has good support for reforming at more northerly latitudes to the North of Scotland

later next week.

 

In Summary today the programmed breakdown in the weather continues to be watered down with every run. The culprit is High pressure over Europe which maintains a ridge West across Scotland early next week with rain from the Low pressure areas to the SW affecting Southern Britain at times. The High transfers South over Europe by the end of next week as Low pressure to the West fills and moves North. Winds then shift SW and a more NW/SE split develops with the South and East seeing the best of by then dry, bright and mild weather close to the High pressure ridge extending from Southeast Europe while the NW stay at risk from rain bearing troughs crossing by on occasion. Given the time of year and as a result of all this it looks unlikely there is any particularly inclement Autumn gales and heavy rain to come with the winds maintaining their period of unusually light strengths that we have seen for some considerable time of late.

 

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

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Based on the ECM 0z, next week will be a fairly cloudy affair, with the best of any sunny spells in the North & NW into the weekend and Monday. Into Tuesday and further on, the fortunes turn, with the west & north becoming fairly wet.. with the driest conditions in the south east corner, though it will stay generally cloudy here. By the following wkend the SE could expect some rain too.

Edited by draztik
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The Ecm 00z ensemble mean shows a locked in warm pattern for the foreseeable future with low pressure to the west/sw of the BI and high pressure to the east with warm southerly winds continuing to pump up from spain & north africa, occasionally a stronger breeze from south of east, sometimes a lighter breeze from the south and eventually trending more towards a brisk breeze from south of west, all of these bring very mild air, indeed it's essentially very warm and humid air with sunny spells and a risk of heavy showers, even a risk of scattered thunderstorms, the pattern is summery and the synoptics shown would bring a scorcher in summer but we are now well into autumn, even so, low to mid 20's celsius sounds realistic when you remember that october's past have brought temps of 27c with very similar charts to these.

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It looks as though the LP is making more of an inroad into the UK on the GFS06Z, certainly in the latter half of the timeframe.

The GFS 06Z run has the low furthest East in a Scandi high set up. This phrase is going to used a lot over the coming 6 months I think Posted Image

(unless there are no Scandi highs of course)

Edited by Captain shortwave
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Pressure build from the South & SW. @ 228HRS Posted Image

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However looks slow progress, that High in Atlantic gonna head our way soon after perhaps, aided by that Low pressure to the NW, moving North-Eastwards.

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Edited by Mark Neal.
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The GFS 06z operational run shows the warm spell lasting for around the next 10 days, eventually the pattern is finally shunted east but doesn't represent a significant pattern change, more of a reboot of the current pattern really with high pressure building in again and the pattern returning to benign mode although it would be cooler than before with a higher risk of slight frosts and thick fog.

 

The next 10 days show winds from the southeast, south and southwest drawing very mild air from either southern europe or the azores, so temperatures would be generally above the seasonal average with some very warm days for the time of year, the weather pattern has a summery look about it and on this run, there are no signs of change in the reliable timeframe so this means warmth, humidity, sunshine, heavy showers with a risk of thunder but at least there should be enough breeze to reduce the risk of fog.

 

There is really very little difference between this run and the ecm 0z op & 0z ens mean, they all look warm for the foreseeable future.

 

 

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So the theme continues this morning, with the models showing the low pressure system in the Atlantic unable to make any significant advance towards the UK proper, as high pressure over Europe keeps it at bay. So, like since late May - we continue to be ruled, in some way, by a stubborn ridge of HP, which is keeping us mild, and fairly dry. Looking at FI there is little hope of any substantial rainfall as we move into October that I can see. It just goes on!

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the gfs ens show a fall in pressure for a time for London, but rises again from the 3rd Oct. Spikes in rainfall are minimal.

 

 

And as a general theme I think its pointing in the right direction.  Don't put bbq's away yet folks

 

BFTP

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And as a general theme I think its pointing in the right direction.  Don't put bbq's away yet folks

 

BFTP

 

well if it's all anything like today here..i'll be BBQ' ing in the drizzle under a leaden coloured sky with a fleece on.

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well if it's all anything like today here..i'll be BBQ' ing in the drizzle under a leaden coloured sky with a fleece on.

Waterproofs and wellies at the ready according to the latest MO update still itl feel pleasantly warm in the waterproofs sweating and downing a burger ...Posted Image

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Latest Meto outlook still going for rain in south and gales in western areas for next week - confusing Posted Image

wow really, I haven't checked it yet, the update is changing every day so perhaps it's not surprising.

Edited by Frosty.
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Waterproofs and wellies at the ready according to the latest MO update still itl feel pleasantly warm in the waterproofs sweating and downing a burger ...Posted Image

yep and manchester is notorious for it's drizzle.Posted Image

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Latest Meto outlook still going for rain in south and gales in western areas for next week - confusing Posted Image

 

The ECM and GEFS ensemble mean both show the LP further East than there op runs. The GFS 06z op run also had the LP further East than last nights 00Z run. Could be also be what the meteo are thinking going by there update?

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The latest met office update is broadly speaking as yesterday and very much as the gfs 06z & ecm 00z op and ens mean shows with the main focus of the heavier rain becoming concentrated across the western side of the uk although all areas have unsettled spells, at least the temperatures are still expected to be on the warm side of average and feeling warm, especially during sunny spells between the showers and more persistent rain, it's not bad really, the further east/se you are, the longer the dry and sunnier, very warm spells would be, there is still that hint of rather colder weather later which today's Gfs 06z op run shows beyond T+240 hours.

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Taking parts of the update discussed above:

UK Outlook for Monday 30 Sep 2013 to Wednesday 9 Oct 2013:

"The unsettled regime looks likely to continue through the rest of this period though the rain will be interspersed by some drier and brighter interludes"

and

"However, temperatures are likely to be above normal and it may feel warm at times, especially in central, eastern and southern areas. Through the following weekend it may turn somewhat colder generally, especially for northwestern areas."

It kind of matches up to the GFS 06z run for early next week?? ECM is pretty close to but keeps the windy weather further west. Rainfall looks showery in nature but being a 5 days + away that could change to anything (or nothing!)

To me it sounds perfectly reasonable as the trough tries to repeatedly go against the High to our NE/E, then getting held back and pushed W and eventually N'wards, before another tries to swing towards the UK again. This squeezes the isobars on the pressure charts indiciating a stronger breeze at times, with perhaps some stronger winds on western coasts. The more east you are, the more likely it'll be warmer and drier at this stage.

All based on today's update and morning model runs, so how far east any low pressure has influence will chop and change each day. It doesn't look like any washout and it will still be drier at times with mild temperatures. Certainly nothing set in stone as I am sure you are all aware.

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Edited by Chris K
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It's as you were from the GEFS 06Z mean, as per the met office update and the ecm 0z mean with a prolonged warm spell ahead due to winds originating in north africa and then drifting up through spain, france in a modified form but essentially the same type of weather with temperatures above the seasonal average and very much on the warm side at times, the airflow eventually veers more to a southwesterly so we swap the african winds for the azores instead, not changing the temperatures much at all. it's not until much further ahead when low pressure to the northwest can force itself further east and introduce a cooler, fresher westerly or northwesterly flow but that's way off in the dim and distant future in meteorological terms.

 

In the reliable and semi reliable timeframe the uk weather will gradually come under the control of a large slow moving atlantic depression to the southwest of the uk with increasingly unsettled, breezier weather but warm and humid with the best of the dry weather and sunshine further east/se, there will be showers and more persistent rain at times, some of it heavy with thunder and occasionally windy across the south and especially the west.

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