Model Output Discussion 18z 28/07/13

[Frosty.]

 So you agree with TwisterGirl81 then, the difference being she seems to like stormy weather in autumn as much as you like mega heat in summer or severe cold in winter(as many others do) all these extremes with have a detrimental effect on people

 

Sorry Mods, last one from me.

Yes I agree with TwisterGirl, especially about staying indoors when the weather is very bad.

[Captain Shortwave]

I think we will need some form of tropical development to help us out here, the synoptics over our part of the northern hemisphere don't exactly scream high pressure over the UK in the near future. A big block over Russia which will naturally mean a trough somewhere between the UK and Scandinavia. The good news is by day 8 nearly all GFS ens have a tropical depression moving northwards into the north Atlantic. GEM also has the same feature which helps build high pressure close to the UK.

ECM did not have this so it will be interesting to see whether it will pick up on this, or whether the GFS/GEM will drop it.

Edited September 11, 2013 by Captain shortwave

[Summer Sun]

ECM looks unchanged so far

 

[Summer Sun]

ECM remains un-keen on shifting the low away like GFS and GEM do

 

 

t192 onwards it did do it this morning so lets see if it does again tonight

[DTHFCJ]

http://www.wetterzentrale.de/pics/MT8_London_ens.png

 

Yo-yo anyone.....

[Captain Shortwave]

Well the ECM has that tropical depression too now. And it's amplifying the atlantic ridge a lot more.

 

What do people want, if the low shifts east we get high pressure over us, if the low sticks we might get the first Arctic blast of the Autumn.

Edited September 11, 2013 by Captain shortwave

[Summer Sun]

http://www.wetterzentrale.de/pics/MT8_London_ens.png

 

Yo-yo anyone.....

 

Still support there for rising uppers for the final part of the month as per the latest met office updates

 

[Skyraker]

That low deepens really quickly on the Fax, it might turn out nasty for all of us.

 

When are the next Fax charts due out?

 

 

 

 

 

To follow the GFS view of how/when/where this low will devlop and move go here

http://www.netweather.tv/index.cgi?action=nwdc;sess=fe669b921dfa10d87c74b08a0b5772d6

 

input in one box the 500-slp chart and in the other the jetstream, and see how the current output may vary from the previous output, a useful check on how consistent the model is being. 

 

one can see how the low develops just ahead of the jetstream (called its left exit) and continues to deepen as the jet strengthens. Note, for those wondering if the low might not be further south) it cannot come south unless the jet is being predicted too far north=unlikely, as all 3 models show a similar area of formation (behind the original low) and track although the depth has some variation between the 3.

Edited September 11, 2013 by Skyraker

[Summer Sun]

ECM ends unsettled its going against what the met office update has but they could be wrong and so could ECM this low is causing a few problems at the moment until the final track of that is sorted anything beyond Tuesday or Wednesday should be viewed with extreme caution

[Frosty.]

I've lost count of the number of times the GEFS mean has shown a warm benign anticyclonic outlook with overnight fog but it's been a lot of consecutive days and here it is again, becoming settled with long sunny periods and light winds with temperatures into at least the low 20's celsius and probably closer to mid 20's c across the south, it will take time for the warmth to come back after such a cool and windy unsettled spell early next week but after midweek the green shoots of recovery should begin to take effect and the last 7-10 days of the month could bring a fine and warm spell to most of the uk...maybe lasting into the first 7-10 days of october.

[Frosty.]

There is something for everyone on tonight's GEFS 12Z control run, a very cool, windy unsettled spell, especially for the north/ne of the uk during the first half of next week and then high pressure building in and intensifying to bring a glorious spell of warm and sunny autumn weather with overnight fog, it's a fair and square run for those who love cool wet and windy weather and those of us who would like one more warm spell before autumn really begins to take hold during october..

Edited September 11, 2013 by Frosty.

[Summer Sun]

Latest from Gibby

 

Good evening. Here is the report on the midday outputs from GFS, UKMO, GEM, NAVGEM and ECM for tonight Wednesday September 11th 2013.

 

All models remain the same for events between now and Sunday with a changeable period expected for most areas as a series of troughs move slowly East and South across the UK over the period. A slow moving waving front over Southern Britain could give a dull and wet day in the South on Friday clearing only slowly on Saturday. The North will then turn windy, cloudy and wet on Sunday spreading to all areas by the end of the day. Temperatures through this period will be close to average after rather muggy day tomorrow in the South.

 

GFS then shows the Autumn storm crossing East North of Scotland late in the weekend followed by a secondary depression crossing the South early in the week with a spell of strong winds, showers and more prolonged rain at times over the UK. In FI tonight High pressure slowly builds back NE over the UK with fine and dry conditions developing as the NW wind eases. This then lasts through to the end of the run before any change to slightly less settled conditions is shown.

 

The GFS Ensembles show an undulating period of uppers which rise and fall as fronts and attendant Low pressure passes through the first half of the run. A wide spread values exist between the members from the mid point of the run with rainfall quantities gradually reducing for a time in the South as we move deeper into the run.

 

The Jet Stream shows the main arm of the flow blowing SE across the UK as we move towards the weekend and in association with Low pressure to the North of the UK on Sunday. As we move through next week the flow maintains it's NW to SE flow over the UK until it weakens later in the week as pressure builds from the SW pushing the flow slowly North.

 

UKMO tonight has Low pressure to the NW of the UK early Sunday moving ESE then SE down the North Sea early next week. The result off this is a period of cool or very cool NW then north winds with rain or heavy showers affecting all of the UK until midweek at least.

 

GEM tonight shows an unsettled start to next week as a showery NW flow following Sunday's wind and rain is replaced by a secondary Low enhancing the wind and rain in the South for a time. Later in the week High pressure does build slowly from the South with fine and dry conditions gradually extending North and east over the UK by the end of next week.

 

NAVGEM shows a UKMO type solution taking Low pressure down the North sea next week to end the run with a Low complex over the North sea and the UK bathed in very cool and showery North winds with some areas of more persistent rain possible near the East Coast.

 

ECM tonight also holds Low pressure over the north sea next week with rain and showers in cool air across the UK. Late in the week the weather moderates to some degree but continues to be changeable with further rain at times as further Low pressure trundles in from the West on somewhat milder Atlantic winds late in the run.

 

In Summary tonight the weather is shown to go one of two ways. We have GFS and GEM on the one side with a spell of wet and windy weather at the weekend followed by a slow improvement next week as High pressure builds from the SW. Alternatively we have UKMO, NAVGEM and ECM all showing Low pressure hanging around in the North Sea for some considerable time next week with a more sustained spell of very and almost exceptionally cool and showery weather. Which is right is hard to call at the moment though with the strength of the power horse models of UKMO and ECM batting on the same side one would probably favour the latter route as more likely to be the correct one.

 

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

[Skyraker]

Does Gibby only post on TWO now?

 

Latest from Gibby

 

Good evening. Here is the report on the midday outputs from GFS, UKMO, GEM, NAVGEM and ECM for tonight Wednesday September 11th 2013.

 

All models remain the same for events between now and Sunday with a changeable period expected for most areas as a series of troughs move slowly East and South across the UK over the period. A slow moving waving front over Southern Britain could give a dull and wet day in the South on Friday clearing only slowly on Saturday. The North will then turn windy, cloudy and wet on Sunday spreading to all areas by the end of the day. Temperatures through this period will be close to average after rather muggy day tomorrow in the South.

 

GFS then shows the Autumn storm crossing East North of Scotland late in the weekend followed by a secondary depression crossing the South early in the week with a spell of strong winds, showers and more prolonged rain at times over the UK. In FI tonight High pressure slowly builds back NE over the UK with fine and dry conditions developing as the NW wind eases. This then lasts through to the end of the run before any change to slightly less settled conditions is shown.

 

The GFS Ensembles show an undulating period of uppers which rise and fall as fronts and attendant Low pressure passes through the first half of the run. A wide spread values exist between the members from the mid point of the run with rainfall quantities gradually reducing for a time in the South as we move deeper into the run.

 

The Jet Stream shows the main arm of the flow blowing SE across the UK as we move towards the weekend and in association with Low pressure to the North of the UK on Sunday. As we move through next week the flow maintains it's NW to SE flow over the UK until it weakens later in the week as pressure builds from the SW pushing the flow slowly North.

 

UKMO tonight has Low pressure to the NW of the UK early Sunday moving ESE then SE down the North Sea early next week. The result off this is a period of cool or very cool NW then north winds with rain or heavy showers affecting all of the UK until midweek at least.

 

GEM tonight shows an unsettled start to next week as a showery NW flow following Sunday's wind and rain is replaced by a secondary Low enhancing the wind and rain in the South for a time. Later in the week High pressure does build slowly from the South with fine and dry conditions gradually extending North and east over the UK by the end of next week.

 

NAVGEM shows a UKMO type solution taking Low pressure down the North sea next week to end the run with a Low complex over the North sea and the UK bathed in very cool and showery North winds with some areas of more persistent rain possible near the East Coast.

 

ECM tonight also holds Low pressure over the north sea next week with rain and showers in cool air across the UK. Late in the week the weather moderates to some degree but continues to be changeable with further rain at times as further Low pressure trundles in from the West on somewhat milder Atlantic winds late in the run.

 

In Summary tonight the weather is shown to go one of two ways. We have GFS and GEM on the one side with a spell of wet and windy weather at the weekend followed by a slow improvement next week as High pressure builds from the SW. Alternatively we have UKMO, NAVGEM and ECM all showing Low pressure hanging around in the North Sea for some considerable time next week with a more sustained spell of very and almost exceptionally cool and showery weather. Which is right is hard to call at the moment though with the strength of the power horse models of UKMO and ECM batting on the same side one would probably favour the latter route as more likely to be the correct one.

 

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

[Summer Sun]

Does Gibby only post on TWO now?

 

Yeah - http://forum.netweather.tv/topic/77405-model-output-discussion-18z-280713/page-116#entry2782426

[Summer Sun]

ECM ensemble goes for pressure to rise at the end of its run

 

 

Anomaly in agreement

 

[SMU]

A very cold unseasonal ECM tonight- enough to wake the winter codgers from their hibernation- MUCH below average for the 10 days & opportunities for snow over the Scottish mountains & frosts elsewhere..

[damianslaw]

Quite a typical outlook for the middle of September which is often a period of transition from the quieter times of the start of the month towards generally more changeable weather by the time we hit the equinox.

 

Early next week is looking decidely autumnal and chilly to boot with a stiff NW wind - the first proper taste of autumn for many..

 

Where we go after this remains uncertain, but as we enter autumn proper the likelihood of high pressure anchoring itself across the country becomes much less likely - my own hunch is that we will remain very changeable with heights to the SW struggling to battle against further low pressure and trough action from the NW.

[Gaz1985]

Thank fully any cool weather won't last - Temperatures on the up from the 20th 

 

 

[SMU]

^^ yes because the modelling will edge towards climatology rather than the recent trend of Autumnal +VE polar heights-

With that in mind the jet will end up further south as time approaches T0

Are people still using the GFS?

[No Balls Like Snow Balls]

A very cold unseasonal ECM tonight- enough to wake the winter codgers from their hibernation- MUCH below average for the 10 days & opportunities for snow over the Scottish mountains & frosts elsewhere..

Ah Mr murr we have been expecting you lol.

[johnholmes]

That low deepens really quickly on the Fax, it might turn out nasty for all of us.

 

When are the next Fax charts due out?

 

 

 

 

the link below is a good one as it shows what time the fax charts have been issued.

the most up to date was this evening and shows the low centre(s) developing further WSW than have been shown before. Note the quite large thermal differences with the thickness lines (the dashed lines) behind the lows cold front. This indicates a large temperature contrast at all levels and will produce a marked jet stream. The surface feature will form either on or just north of the jet, seen from the surface, and very probably at what is called the left exit, an area noted for marked deepening. The T+120 will probably be issued any time now

http://www.weathercharts.org/ukmomslp.htm#t120

 

looking at the latest for the 12z output and Met appear to have decided that the low is going to be further south, so it will be interesting to see just where they place it on their T+120 Fax soon to be issued?

Edited September 11, 2013 by johnholmes

[john pike]

updated fax 96

 

 

120

 

[johnholmes]

updated fax 96

 

 

 

120

 

 

those are not the latest John, the link I gave shows quite a change from those positions. their T+120 is very similar to their raw model output with a centre of below 972mb over Orkney.

If this turns out to be correct then stronger winds than GFS was suggesting seem likely over areas further south.

I would be surprised if the man/machine mix of the latest Fax is not nearest the mark. For them to have made such a change must mean they are pretty confident in the data they are receiving regarding the various parameters that go to developing a fairly major storm, tight thickness gradient, vorticity in the right place at the right time, the jet stream in the right place etc.

The 00z outputs from all 3 major centres will be interesting to see which idea is gaining preference with only 72 hours to run from 00z tonight.

 

for info again the Fax chart link which shows the date/time of issue of each chart; always take the later issue as being the latest ideas from the senior man.

http://www.weathercharts.org/ukmomslp.htm#t120

Edited September 11, 2013 by johnholmes

[john pike]

those are not the latest John, the link I gave shows quite a change from those positions. their T+120 is very similar to their raw model output with a centre of below 972mb over Orkney.

If this turns out to be correct then stronger winds than GFS was suggesting seem likely over areas further south.

I would be surprised if the man/machine mix of the latest Fax is not nearest the mark. For them to have made such a change must mean they are pretty confident in the data they are receiving regarding the various parameters that go to developing a fairly major storm, tight thickness gradient, vorticity in the right place at the right time, the jet stream in the right place etc.

The 00z outputs from all 3 major centres will be interesting to see which idea is gaining preference with only 72 hours to run from 00z tonight.

 

these are the updated ones john

 

check top left corner

 

http://www.weathercharts.org/ukmomslp.htm#t120

Edited September 11, 2013 by john pike

[johnholmes]

that shows the date as 10th John, it is the 11th and the chart below is the latest

 

 

Edited September 11, 2013 by johnholmes