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Model Output Discussion 31/03/14 onwards.


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Posted
  • Location: Reigate Hill
  • Weather Preferences: Anything
  • Location: Reigate Hill

No surprise the GEM 12z op from yesterday has backtracked as it was another outlier:

 

GEM 12z op:post-14819-0-31750700-1399957333_thumb.p  Compared to its mean at the same time: post-14819-0-43191700-1399957354_thumb.p

 

This mornings output for the same time: post-14819-0-14612800-1399957379_thumb.p

 

Very similar to ECM 12z.

 

GFS OP continues with its consistent output. The trough has covered the UK by midday Sunday: post-14819-0-91283400-1399957492_thumb.p

 

On this run it is a week before it retrogresses north: post-14819-0-86839800-1399957557_thumb.p

 

Heights to our east keep it from moving and it stays in situ filling before reinvigorating before it retreats. The control run also has Sunday midday as when the trough reaches the south coast. However 6 members of the ensembles delay this till early Monday. However 100% of the members have the UK in the trough by midday Monday. The mean at that time:

 

post-14819-0-15643700-1399958053_thumb.p

 

By T192 there are now no members similar to  yesterday's ECM 12z op. Solid continuity for a UK trough, the mean:

 

post-14819-0-93353800-1399958903_thumb.p

 

The NOAA 8-14 day remains in line with the GFS mean: post-14819-0-85998400-1399959044_thumb.g

 

I think ECM may backtrack again. Last night's 12z had little support from its ens; D8 it was 6c above the 2m temp mean:

 

post-14819-0-50662100-1399959191_thumb.g

 

Still confident GFS has nailed this pattern change, though you never say never with the weather.

 

 

 

 

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Posted
  • Location: Camborne
  • Location: Camborne

Quick note before copious amounts of coffee, that just supports previous comments.

 

GFS

Very warm on Friday and Saturday still but Sunday the low is 996mb over the Faroe Islands with associated fronts lying across northern England. Quite wet for most of the country except the SE which will still see the last of the, very brief, hot spell.

 

GEM

 

Sunday the low further north with fronts lying N. Ireland/N. Scotland thus prolonging the hot spell in England into Sunday.

Edited by knocker
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Posted
  • Location: st albans
  • Location: st albans

No surprise that healthy debate flourishes in here. I'm wondering what the point is of the Gfs model whilst others post that it has the pattern nailed.

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Posted
  • Location: Peterborough
  • Weather Preferences: Snow and frost in the winter. Hot and sunny, thunderstorms in the summer.
  • Location: Peterborough

I was going to write a rant about the GFS and it's poor handling of blocks to the north east of the UK. Unfortunately this mornings ECM happened.

Posted Image

 

Nice consistency ECM (someone give the computer a kick)  :nonono:

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Posted
  • Location: st albans
  • Location: st albans

I was going to write a rant about the GFS and it's poor handling of blocks to the north east of the UK. Unfortunately this mornings ECM happened.

Posted Image

 

Nice consistency ECM (someone give the computer a kick)  :nonono:

Ditto cap'n. Spreads have been large on this on all the ens so wouldn't be awarding rosettes yet. This op run was not expected, given the way the models were evolving on this.
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Posted
  • Location: Camborne
  • Location: Camborne

The surface analysis from ECM that differs from GFS and GEM Although by Tuesday the GFS and ECM are singing from the same hymn book. Beam me up Scotty.

post-12275-0-71079800-1399963787_thumb.p

post-12275-0-51475000-1399963795_thumb.p

post-12275-0-34171200-1399963803_thumb.p

Edited by knocker
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Posted
  • Location: bingley,west yorks. 100 asl
  • Location: bingley,west yorks. 100 asl

I wonder if the upgrades ecm went through are making it perform less consitently lol.

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Posted
  • Location: Kilmersdon Radstock Somerset
  • Weather Preferences: None Really but a snow lover deep down
  • Location: Kilmersdon Radstock Somerset

HERE IS THE LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM TODAY TUESDAY 13TH MAY 2014.

 

THE CURRENT GENERAL SITUATION. A weak and shower NW flow will ebb away today as High pressure steadily builds into the UK from the SW tonight and tomorrow.

 

GFS The GFS Ensemble pack today indicate the fine period towards the end of next week and the start of the weekend will give way to Low pressure moving SE across the UK to start next week. Rain and showers will develop for many on Sunday and continue to affect the UK through next week. The rest of the run shows the ensemble pack continuing to show at best showery weather for many with plenty of shallow Low pressure around the UK though with conditions warming over Europe it could become rather humid later over the UK.

 

UKMO UKMO shows Low pressure sinking slowly SE towards the UK at the end of the coming weekend with a UK trough delivering outbreaks of rain and showers as well as lowering temperatures back to average levels in winds from the SW or West.

 

GEM The GEM operational is somewhat different than the rest with Low pressure settling more towards being to the South of the UK while higher pressure develops towards the far North of Britain keeping things drier there while Southern areas see a cool and cloudy easterly breeze with outbreaks of rain at times.

 

NAVGEM NAVGEM continues to show Low pressure slip down into the UK from the NW later next weekend with rain and showers developing for all to start next week.

 

ECM today shows it's operational run has moved in line with it's recent ensemble pack by dropping Low pressure down across the UK from the North late next weekend and maintained through much of next week. Rain at times will be commonplace for all areas as a result with some drier and brighter spells mixed in with temperatures returning close to average generally.

 

MY THOUGHTS  For those looking for a sustained period of fine and warm weather following it's intervention into this showery Spring late this week had better look away now as by the end of the weekend and certainly next week Low pressure will move down across the UK on Sunday and though next week. There are a few differences in the extent of low pressure shown but the general message remains the same from all models in that all areas can expect some rain at least from Sunday on and through most days of next week as Low pressure settles close by to the UK. Looking into the far reaches of the output this morning there are embryonic signs that it may become slightly warmer, more humid and less showery in 2 weeks from now but there is little cross model agreement on any definitive weather type shown for then this morning.

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Posted
  • Location: Reigate Hill
  • Weather Preferences: Anything
  • Location: Reigate Hill

Possible thunderstorms spreading from the south heading north this afternoon and evening:

 

post-14819-0-26477800-1399966372_thumb.p post-14819-0-23313400-1399966380_thumb.p

 

 

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Posted
  • Location: Camborne
  • Location: Camborne

One thing i struggle with as someone fairly new to model reading is knowing where the weatherfronts will be. Tonights ECM for example looks quite dry to me, but some posts above are saying some rain will be about.

 

I know that the fronts are where the airmasses meet, so as an example below, am i reading it correctly that the charts below from tonights ECM show a front to the north west of Scotland, along the green band?

 

Posted ImagePosted Image

 

There are others on here far more expert than me that can answer this question in detail. What i will say is that if you are trying to identify fronts from the upper air output I think you need charts with rather more detail. The ones you chose are very broad brush. The same also applies to surface output. What you say is broadly speaking correct, the front will show where there are a tightening of isotherms (and contour lines) indicating a strong temperature gradient but there is more to it than this and as I have already mentioned I think you need more detailed charts which the forecaster will have available. You can get access to these but they are normally behind a paywall. The easiest pay is just pick them out on the precipitation forecast charts. Perhaps do a google search and find a guide to reading upper air output. I'm saying no more without consulting my lawyer.

Edited by knocker
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Posted
  • Location: Darlington
  • Weather Preferences: Warm dry summers
  • Location: Darlington

ECM ensemble has certainly remained consistent in a more unsettled outlook of late and now the Op has moved towards it best make the most of the next few days for warmth and sunshine next week looks more unsettled

 

Posted ImagePosted ImagePosted ImagePosted Image

Edited by Summer Sun
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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

There are others on here far more expert than me that can answer this question in detail. What i will say is that if you are trying to identify fronts from the upper air output I think you need charts with rather more detail. The ones you chose are very broad brush. The same also applies to surface output. What you say is broadly speaking correct, the front will show where there are a tightening of isotherms (and contour lines) indicating a strong temperature gradient but there is more to it than this and as I have already mentioned I think you need more detailed charts which the forecaster will have available. You can get access to these but they are normally behind a paywall. The easiest pay is just pick them out on the precipitation forecast charts. Perhaps do a google search and find a guide to reading upper air output. I'm saying no more without consulting my lawyer.

 

picking up on where Knocker was explaining, you can see these fronts on the Met Fax chart that go out to T+120 and are updated through each day, compare that with the upper air charts and it should begin to help you understand a little more. Believe me it is not always easy to fit surface features to the upper air pattern. The short answer is where there are large changes predicted at 850 and 500mb temperature levels then you are likely to find fronts. In the case of warm fronts then the temperature lines will be mainly ahead of the surface warm front. With a cold front they are packed behind the surface feature. Hope these two posts help a bit?

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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

Going on from Gibbys' assessment the 500mb anomaly charts at 6-10 days, NOAA and EC-GFS are pretty much along similar lines, air originating from Canada about the same latitude as southern Greenland so coolish and unsettled more likely than warm and settled in the period up to 23 May and the 8-14 NOAA keeps a similar idea, see below, that is a marked upper trough feature with some negative heights still suggested close to the UK. Thus after our shortish warm dry spell setting in from tomorrow into the weekend the outlook for May is coolish and fairly unsettled I would suggest?

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

Edited by johnholmes
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Posted
  • Location: Reigate Hill
  • Weather Preferences: Anything
  • Location: Reigate Hill

The GEM mean has also ignored its op run of late and again is in line with the other mean charts:

 

Monday: post-14819-0-39791100-1399973703_thumb.p  D10: post-14819-0-62362100-1399973724_thumb.p

 

Good cross-model support now with regard to  the timing and location of the trough, though the latter may moderate and probably its angle and how the low interacts may all  change, so surface conditions difficult to pin down; though cooler and wetter look a good bet. For example NOGAPS slightly further East:

 

Monday: post-14819-0-54165600-1399974165_thumb.p  D10: post-14819-0-85866400-1399974174_thumb.p

 

The ECM De Bilt op and control tally very closely with the mean for temps, which is a first for ECM for a while:

 

post-14819-0-06441800-1399974064_thumb.p  edit; ditto London: post-14819-0-72480800-1399982294_thumb.g

 

Now all we need is a few more runs with this consistency and we can see what follows; of which there is no clear signal yet. 

Edited by i'm dreaming of...
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Posted
  • Location: Camborne
  • Location: Camborne

There isn't a huge difference between the GFS and ECM next week regarding the upper air analysis apart from the orientation of the cold air. It will be interesting to see how they progress thisas  it is looking quite unsettled on the surface which fits in with the ops runs. Early days as there are quite a few variations on a theme possible here.

post-12275-0-81291000-1399976477_thumb.p

post-12275-0-31390400-1399976486_thumb.p

Edited by knocker
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Posted
  • Location: Camborne
  • Location: Camborne

There is something a bit strange on the 06z GFS.

 

The N. Atlantic chart for 12z Monday has a low 1000hPa just west of Worthing with precipitation over most of England. Yet it has STs of mid to upper 60s east of a line Bournemouth to Hull. Seems very unlikely to me. Time for a power nap.

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Posted
  • Location: Maltby, Rotherham - 150m ASL
  • Weather Preferences: Snow and Cold! Winter :)
  • Location: Maltby, Rotherham - 150m ASL

There are others on here far more expert than me that can answer this question in detail. What i will say is that if you are trying to identify fronts from the upper air output I think you need charts with rather more detail. The ones you chose are very broad brush. The same also applies to surface output. What you say is broadly speaking correct, the front will show where there are a tightening of isotherms (and contour lines) indicating a strong temperature gradient but there is more to it than this and as I have already mentioned I think you need more detailed charts which the forecaster will have available. You can get access to these but they are normally behind a paywall. The easiest pay is just pick them out on the precipitation forecast charts. Perhaps do a google search and find a guide to reading upper air output. I'm saying no more without consulting my lawyer.

 

 

picking up on where Knocker was explaining, you can see these fronts on the Met Fax chart that go out to T+120 and are updated through each day, compare that with the upper air charts and it should begin to help you understand a little more. Believe me it is not always easy to fit surface features to the upper air pattern. The short answer is where there are large changes predicted at 850 and 500mb temperature levels then you are likely to find fronts. In the case of warm fronts then the temperature lines will be mainly ahead of the surface warm front. With a cold front they are packed behind the surface feature. Hope these two posts help a bit?

 

Thank you knocker and johnholmes for your time and replies :) 

They have indeed helped. Always a learning curve the weather isnt it. Very fun though!

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Posted
  • Location: Maltby, Rotherham - 150m ASL
  • Weather Preferences: Snow and Cold! Winter :)
  • Location: Maltby, Rotherham - 150m ASL

Well so far on todays 12z runs the GFS and UKMO keep the low coming down and across us on Sunday afternoon, so it does look like a breakdown is coming after an all to brief taste of summer:

 

Posted ImagePosted Image

 

Good agreement there actualy, they look very similar to me!

Edited by Winter Cold
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Posted
  • Location: Peterborough
  • Weather Preferences: Snow and frost in the winter. Hot and sunny, thunderstorms in the summer.
  • Location: Peterborough

Both the GFS and UKMO eventually centre the low over Ireland next week. Meaning the warm summery conditions are just over the other side of the north sea.

Standard  :rofl:

Posted Image

 

Considering the set up going forward, you can't rule out the chance of warmer air trying to push in from the continent with thundery rain in tow if that did happen. Otherwise it is a fairly slack showery south/south westerly flow with temperatures around average.

 

GEM on the other hand

Posted Image

Posted Image

Still trying to bring warmer and more humid conditions next week

Posted Image

Decent 850s

Edited by Captain shortwave
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Posted
  • Location: Darlington
  • Weather Preferences: Warm dry summers
  • Location: Darlington

Whilst the other models go for something cooler next week GEM prefers to go a warmer humid route wouldn't rule out some thunder at times if GEM comes off

 

Posted ImagePosted ImagePosted ImagePosted ImagePosted Image

Posted ImagePosted ImagePosted ImagePosted ImagePosted Image

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Posted
  • Location: Keyingham, East Yorkshire
  • Weather Preferences: Spanish plumes, hot and sunny with thunderstorms
  • Location: Keyingham, East Yorkshire

Now that the UKMO has moved in a more unsettled direction i am starting to believe thats the direction things are heading. So chances are, we will see an unsettled week next week with showers of longer spells of rain. But temperatures dont look too bad. A welcome taste of summer to come between now and then though.

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Posted
  • Location: Camborne
  • Location: Camborne

Well according to the GFS Sunday is rapidly removing itself from the hot spell. At 12z the low is off NW Ireland with frontal troughs bringing rain down from the NW during the day.

 

The significant aspect is the colder air behind the troughs. Temps down to the the low 40s and even upper 30s in the west Midlands, Wales and NW England by 00z Monday.

 

By midday Monday the low is over Shannon 992mb.

Edited by knocker
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Posted
  • Location: Exeter, UK
  • Location: Exeter, UK

Thank you knocker and johnholmes for your time and replies :) 

They have indeed helped. Always a learning curve the weather isnt it. Very fun though!

 

As mentioned already it isn't easy looking at simple synoptic charts of parameters such as pressure or temperature to try and identify fronts. However, if you have access to charts with station circles and begin to plot a few simple variables, such as isobars, isodrosotherms (areas of equal dewpoint - very useful as different air masses will have different humidities, and a front divides airmasses!) and try and spot wind veer...combine that with simple knowledge of clouds and types of weather you'd expect along different fronts and you'd actually not do too badly identifying where they are!

 

However, it's much easier to look at the charts with these frontal features already positioned for you :wink:

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Posted
  • Location: Nuneaton,Warks. 128m asl
  • Weather Preferences: Snow then clear and frosty.
  • Location: Nuneaton,Warks. 128m asl

No change to the outlook for the rest of this week then with the all to brief warm up from tomorrow being replaced by the approaching low from the west bringing the cooler unsettled conditions for all by Sunday.

UKMO T120hrs-Sunday

post-2026-0-12972200-1400002954_thumb.gi

 

GFS for Saturday shows the change already into the west and north of the UK.

 

post-2026-0-33349000-1400002541_thumb.pnpost-2026-0-31455700-1400002553_thumb.pn

 

the far SE just about holding on to the warmth until the day's end.

Looking further ahead into next week this appears from the ens outputs today to have all the makings of a stalling pattern as the Russian block holds firm to the east.

 

This would keep things showery with sunny periods as the trough remains in-stu near the Uk taking some time to gradually fill. 

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