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

[Summer Sun]

After almost 2 hours of no internet I am finally back online

 

Here's the latest from Gibby

 

Good evening. here is tonight's look at the 12 noon outputs issued by GFS, UKMO, GEM, NAVGEM and ECM for today Wednesday September 18th 2013.

 

All models show another depression steaming over the Atlantic to the North of Scotland carrying a system of troughs over the UK tomorrow with a spell of cloud, wind and rain for all before brighter skies return later in the day in milder air than of late. Through Friday, the weekend and the start of next week High pressure will build across the UK from the South, taking its time to reach the North with a few more days of cloud and drizzle here before fine and dry weather extends up here as well early next week. With warm air over the UK the temperatures should comfortably reach the low 20's in the afternoons in the South but nights will be cool with mid single digit minima and an increasing risk of fog as winds stay light, slow to clear in the morning.

 

GFS then shows several more days of fine and settled weather as High pressure just slowly ambles East of the UK with a Southerly flow developing in the West. However, any rain from this is very limited in its spread Eastwards with te High to the East holding ground and warding off any major attacks from the West of any wind and rain and maintaining a lot of dry and benign conditions especially in the south and East.

 

UKMO shows High pressure close to the SE on Monday with fine and warm conditions away from the far NW. by Tuesday a new High builds in from the Atlantic lowering the temperatures somewhat as fresher air moves in with fine and bright

days continuing but with mist and fog by night in rather chilly conditions.

 

GEM tonight maintains High pressure over the UK only slowly slipping SE later in the week maintaining a ridge back up over the UK from the SE. Though temperatures may fall a little later in the week as the warmest of the air leaks away the weather will stay generally pleasant and benign with bright and dry days with some sunshine and cool and misty nights with some fog patches.

 

NAVGEM too looks very similar as High pressure is shown to lie across the British Isles for much of next week with fine and bright days and the aforementioned mist and fog at night.

 

ECM shows a temporary blip through the middle of next week as a Low crosses by to the North and sends a rain bearing trough across the UK before the return of high pressure builds up from the SW again late in the week.

 

The GFS Ensembles show good support for a fine and warm period through next week with a slow decline in temperatures as the week ages with more changeable and cooler conditions arriving for most by the end of the run.

 

The Jet Stream is scheduled to move North through the rest of the week to the North of the UK where it remains for some considerable time. The pattern in the longer term is far less clear tonight and not worth commenting on.

 

In Summary the weather is set to become anticyclonic over the weekend and for much of next week. There is a blip shown by ECM through the middle of next week as an Atlantic Low and fronts brush by but this seems the exception to the general rule of fine weather continuing for the reliable timeframe albeit the warmest conditions by day will be early in the week as there is some support for temperatures declining somewhat later in the week with cool and potentially locally foggy nights throughout.

 

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

 

[Tony27]

2 hours of no internet how did you survive gavin?

Edited September 18, 2013 by Tony27

[Captain Shortwave]

Well hello there

 

Much better run for Monday, in fact with the winds from the south that should be a 25C+ chart.

Well the temperature chart shows 24C widespread across central/southern England

Should be able to eek a little more out of that set up if it happened 

Maxima for the weekend

Saturday - 22C* (there is a 23C in southern Ireland)

Sunday - 24C

In fact even Tuesday would be warm in the south

Edited September 18, 2013 by Captain shortwave

[Gaz1985]

Here comes the high pressure filled weekend 

 

 

 

High pressure still close by into the new week, could be a lot worse! 

 

[Frosty.]

The models look great, the weekend will warm up significantly to just above average, low 20's celsius but when the tropical maritime airmass sweeps northeastwards across the uk, it will bring a lot of cloud with it but it should thin and break to allow sunny spells and that's when temps will be boosted to 22 or 23c, by sunday or monday an even warmer continental airflow from more of a southerly point will draw drier air north with clearer skies and lots of sunshine which is then set to continue for most or all next week with winds becoming light and variable with sea breezes and max temps inland being well into the 20's celsius and high pressure over the uk.

[mushymanrob]

well its not looking like wall to wall warmth... both the ukmo and ecm suggest a temporary cooling down (slightly) as we lose the higher upper tues/weds before the higher uppers return later next week.

 

so anticyclonic domination starts from tomorrow and for the forseeable, with varying degrees of warmth and sunshine. after today theres no real sign of any more rain.

 

interestingly i see gibby mentions fog for prone areas, which some of us raised a few days ago. this morning its not imho looking like an immediate problem, but one that looks like becoming more widespread IF and WHEN we lose the warmer uppers. so whilst we have uppers of 10c + i personally dont think itll be much of an issue, but get below 5c then the chances increase, although im no expert on fog!

[Frosty.]

This is interesting...well I think it is anyway ...here is a comparison between the GFS 00z operational run versus the GEFS 00z mean at T+144 hours, it just shows you should never take an op run as gospel, however, you cannot take the mean as gospel either but the balance of probability would show the mean as the one most likely, the gefs 00z mean shows a very warm and settled spell for the southern half of england & wales next week, the further north you go, the less warm and less settled it becomes but for the south it would be a superb week, this weekend will be turning warmer, into the low 20's c with variable cloud amounts and sunny spells.

[johnholmes]

Thur 19 ST

the latest output from ECMWF-GFS shows yet another change for the 6-10 and probably out to at least 15 days in terms of unreliability of these charts.

http://www.meteo.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

 

Ec-gfs on 19 Sept

And another change with ec, gone is the ridge/+ve heights and the trough is back to some degree although the contours still show a v slight ridging over the uk

Gfs keeps the ridge/+ve heights but as a deepish looking trough now fairly close to e uk!!

Continuity ain’t what they are showing!

 

The NOAA version is rather more consistent over the last few days, suggesting a building upper ridge as the link below shows, the 8-14 is less so but that is the usual pattern with these NOAA outputs, only rarely does the 8-14 show a more definite pattern than the 6-10

http://www.cpc.ncep.noaa.gov/products/predictions/610day/500mb.php

 

So some kind of upper ridge from the west or WSW seems the most likely in the 6-15 day time frame but there is still doubt about this, certainly as to how marked it might be.

[Captain Shortwave]

Well all the models agree on a warm spell from Saturday through until Tuesday, in fact the GFS has 26C as a maximum on Tuesday which is very good for late September. Most models are now going for a trough to develop over Scandinavia and bring a weak cold front south over the UK, which then leads us into cooler and fresher weather, but still settled.

GFS and ECM look broadly similar

 

Something very different from the UKMO though with a much stronger ridge over the UK

 

The ECM seems to be picking up more of a westerly push by the end of next week, as in movement of the upper pattern, this is something to watch in the upcoming output.

Edited September 19, 2013 by Captain shortwave

[No Balls Like Snow Balls]

Oooo the temps take a tumble again after Tuesday according to ECM 12z ensembles. Can see the 00z ensembles going this way to looking at the op run.

 

 

Still looks settled even after Tuesday, but anything after Tuesday is FI land, wouldn't be surprised to see it turn more unsettled perhaps.

 

The warm spell isn't looking very long again this morning.

Edited September 19, 2013 by No balls like Snow Balls

[Summer Sun]

2 hours of no internet how did you survive gavin?

 

Easy I used my mobile

 

[No Balls Like Snow Balls]

Couple of updates from Matt Hugo re model winter offerings

 

Sept update of the EUROSIP model gives little idea for winter, but EC seasonal shows high pressure over or just to the W of the UK as an avg.

 

 

EC seasonal highlighting a possible -ve AO pattern in Jan/Feb in particular, so perhaps any cold weather later on rather than early winter.

[Frosty.]

Easy I used my mobile 

Same here gavin, I would be lost without my blackberry...models show a taste of summer next week with temps in the low to mid 20's celsius.

[Captain Shortwave]

Oooo the temps take a tumble again after Tuesday according to ECM 12z ensembles. Can see the 00z ensembles going this way to looking at the op run.

 

ensemble-tt6-london.gif

 

Still looks settled even after Tuesday, but anything after Tuesday is FI land, wouldn't be surprised to see it turn more unsettled perhaps.

 

The warm spell isn't looking very long again this morning.

Cross model agreement for 4 days (Sat-Tues), unless the UKMO is correct, then it would be longer. Scatter appearing from Tuesday onwards. No big surprise there given the split flow set-up.

The Eurosip output sounds similar to my winter forecast (wild guess), probably drunk like I was at the time 

[Summer Sun]

Latest from Gibby

 

Good morning everyone. Here is the report on the midnight outputs from GFS, UKMO, GEM, NAVGEM and ECM for today Thursday September 19th 2013.

 

All models show a system of troughs crossing steadily East over the UK in association with a Low pressure area swinging east to the North of the UK. All areas will see a spell of rain today followed by dry and fine weather this evening tonight as pressure rises. Tomorrow will be a dry and bright day with a weak ridge crossing the UK slowly through the day with some bright sunny spells and respectable temperatures. Over Saturday pressure will of risen well but a warm front will be crossing NE across the UK with a lot of cloud in the South and thick cloud to northern and Western areas with rain and drizzle in places. It will feel increasingly warm and humid. Then from Sunday and into the start of next week drier air is shown to filter North across the UK in association with High pressure just to the East of Britain with cloud breaking and sunny spells developing and it will become warm in the South and East but with the risk of fog at night increasing.

 

GFS then shows cloud in the far NW finally breaking up while transferring to NE coasts as a new High builds in from off the Atlantic. This drags some cooler uppers across the East of the UK with cloud amounts larger it will feel rather cooler for a time here with the best of the brightness and daytime warmth likely towards the West. High pressure is then shown to dominate over the UK for the remainder of the run but of a much colder variety with rather chilly air over the UK, pleasant enough in daytime sunshine but jolly chilly and potentially foggy conditions overnight slow to clear in the morning's.

 

UKMO today shows things rather warm and dry to start next week with High pressure well established over the UK giving all areas even the NW by then some decent dry and bright weather with temperatures above average by day with mist and fog patches overnight.

 

GEM is a little like GFS this morning with the precursor to building High pressure in off the Atlantic allowing a chilly NW feed to drag cooler uppers across Britain through next week meaning after a warm start temperatures will fall back but the weather remain largely the same with dry and bright days with cool nights with fog patches. Late in the run pressure leaks away as the High pressure slips SE into the Continent with Atlantic fronts and SW winds bringing the threat of rain into the UK from the SW by the end of the run.

 

NAVGEM shows High pressure across the UK early next week being squeezed into a ridge by late in the week. After a warm start it looks like temperatures will decline later in the week as cooler uppers get drawn in. Nevertheless, fine weather holds on for most with sunshine by day and cool, misty nights with little if any rain likely for most next week.

 

ECM looks a little like GEM this morning pulling High pressure away SE later next week and allowing unsettled and rainy conditions to replace it soon after midweek as fronts cross NE as the High declines SE into europe. The potential is there for much colder conditions to arrive at the tail end of next week and through the weekend as cold air arrives from the North.

 

The GFS Ensembles are firming up on showing the cool down as described above in one form or another following several warm and settled days early next week. There are some very cool options on the table with some members also introducing Low pressure and rain into the mix towards the end of the output.

 

The Jet Stream shows the flow moving North of the British mainland over the coming days where it is maintained for a time. Later next week it shows signs of moving South over the UK again in response to High pressure declining away from the UK. The end part of the run is very undecided with pockets of flow shown at various latitude with some suggestion it may end up South of the UK but this is very speculative at this range.

 

In Summary this morning the fine spell is still well and truly on the way though with subtle differences coming to light this morning. In the first half of next week things look clear cut as it will simple become dry, bright and reasonably warm for most of not all of Britain with a fog risk at night. Thereafter subtle movements in the high pressure could mean the Uk engages colder air into the circulation as the cold surge in northern Europe becomes perilously close to the East on some output. Other output such as GEM and ECM shows a seepage of warmth too but this time as Atlantic low pressure feeds over a declining High pressure moving SE into Europe resulting in a return to cooler and unsettled conditions late next week. ECM goes one step further with a particularly chilly looking 10 day chart with rain on a vigorous cold front slipping SE would be followed by a marked drop in temperature with potentially wintry showers over Northern hills and frost at night in the days that follow. So enjoy the warmth and sunshine early in the week because it might not last too long after midweek.

 

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

 

[Captain Shortwave]

GFS 06Z

 

GFS 00Z for the same time

 

Completely different, Tuesday onwards is definitely our sticking point at the moment when it comes to uncertainty 

Edited September 19, 2013 by Captain shortwave

[Frosty.]

The ECM 00z ensemble mean is an absolute BEAUTY....it's just as impressive as yesterday and shows the weather turning warm during this weekend and then very warm for the time of year by early next week and the fine & sunny anticyclonic spell persists all through next week across most of the uk with a risk of overnight mist and fog patches but it's a superb run for late september with another taste of the recent summer..ENJOY

[johnholmes]

High pressure yes frosty but sunshine in the amounts you are talking of?

I would urge some caution on that, dependent on where anyone lives and paying careful attention to the TD and wind track.

 

That is of course on top of the variability of different models in how they deal with the synoptic set up, just look at the difference between the 00 and 06z GFS?

Edited September 19, 2013 by johnholmes

[Frosty.]

High pressure yes frosty but sunshine in the amounts you are talking of?

I would urge some caution on that, dependent on where anyone lives and paying careful attention to the TD and wind track.

 

That is of course on top of the variability of different models in how they deal with the synoptic set up, just look at the difference between the 00 and 06z GFS?

Yes John, i'm just happy to see high pressure and warm uppers, that is most of the battle won already.

Edited September 19, 2013 by Frosty.

[Geordiesnow]

The outlook does look mainly dry for most and for a warm up and even if your under the cloud/drizzle in the NW the feel of things should be warmer due to the very warm airflow from the SW. 

 

I think the uncertainty stems into Next week although more in terms of temperature with hints we may get something cooler from the North but some outputs have shown high pressure staying over us so it should remain warm and sunny for most. 

 

Shame that there will probably be more cloud around for most Northern areas on Saturday than previous thought barring a last min trend of edging the ex TS further North-Westwards but a last burst of summer warmth is still on the cards though. 

[Frosty.]

A quick look at how I think the temperatures will improve in the days ahead, not much change tomorrow as it will be rather cloudy across the board, 15-17c, saturday closer to 20c in the south/se and nearer 16-18c further north & west and on saturday it's a nw/se split with some rain and fresh sw'ly winds for the far northwest of the uk but away from there, it looks dry and bright with sunny spells and temps feeling pleasantly warm at around average values, by sunday it will be a little warmer at around 22c for the south/se and 17-19c further north/west, then next week it continues to warm up with sunny periods and light winds with temps into the low to mid 20's celsius, parts of the south will probably exceed 80F at times next week so it will be feeling like it's summer again although sunshine amounts will be variable and overnight mist and fog would need additional time to burn away.

Edited September 19, 2013 by Frosty.

[Summer Sun]

Every chance now as well of finishing above average for the CET which would make it 3 above average months in a row with this warmer weather coming this weekend and into next week

 

Rainfall also looks low for most of us for the next 16 days

 

 

Also CFS continues to back high pressure and mild weather dominating our weather next month

 

Update from 2 days ago - http://forum.netweather.tv/topic/77189-autumn-2013-thoughts-prospects-and-forecasts/?p=2789503

 

And today's update - http://forum.netweather.tv/topic/77189-autumn-2013-thoughts-prospects-and-forecasts/?p=2790794

 

Of course given its October fog could become an Issue but once its burns away temperatures would respond

Edited September 19, 2013 by Summer Sun

[mushymanrob]

 

The warm spell isn't looking very long again this morning.

 

.... that depends which set of data you chose to believe.

 

the 06z gfs brings the warm upper (10c isotherm) over the country on saturday, and for at least half the country thats where it stays until next friday... 7 day of potential warmth. that run also suggests we are under at least the 5c upper for most of the country for most of the run.

 

ok thats possibly the run that suggests the warmest scenario.... and we are likely to get something less then what the 06z gfs would have us believe. but so what? the outlook is warm/above/near average... thatll do for me!

[Scorcher]

.... that depends which set of data you chose to believe.

 

the 06z gfs brings the warm upper (10c isotherm) over the country on saturday, and for at least half the country thats where it stays until next friday... 7 day of potential warmth. that run also suggests we are under at least the 5c upper for most of the country for most of the run.

 

ok thats possibly the run that suggests the warmest scenario.... and we are likely to get something less then what the 06z gfs would have us believe. but so what? the outlook is warm/above/near average... thatll do for me!

 

The ECM op runs have consistently been warmer than the GFS as well- the 00Z shows the 15C isotherm covering much of the UK on Monday- in fact only the north west of Scotland just misses out.

[Frosty.]

The GFS 06z operational run shows an anticyclonic spell and a big warm up by early next week with temps rocketing into the mid to high 70's F, I would not be surprised if some parts of the south & east reach 27-28c during next week, the uppers certainly look good enough, very impressive by late september standards and indeed, summer, so the 6z shows a very warm spell with increasing amounts of sunshine as time goes on and light winds but from a week tomorrow it turns generally unsettled but continues just on the warm side of average across the south of the uk, trending cooler across the north and more cyclonic across the uk, the unsettled weather is most persistent across the north & west later in FI with occasional high pressure in the southeast where the best of the weather would be, however, I think the unsettled FI is unlikely as i'm going with the much more settled/benign ecm 00z ens mean as guidance with the settled spell set to continue into october.

Edited September 19, 2013 by Frosty.