Model Output Discussion 30/06/2012

[snowfluff]

So 3 days into a mean 6 week period you are dismissing GP's thoughts?

At least read the post properly that you are quoting.

Perhaps, but his forecast for summer predicted "above average temps, and below average rainfall,issued June 1.

[Alex]

Perhaps, but his forecast for summer predicted "above average temps, and below average rainfall,issued June 1.

Seasonal forecasting is extremely difficult and at least the effort was made, he often gets the trend correct - certainly this winter was well thought out! I think the problem with this summer has been the atmosphere acting in a Nina base state ie low angular momentum, MJO locked in phase 1/2 and a record low GWO to start July, who would of thought this when the atmosphere should of been at Least neutral like if not Niño like. You should see a far improved August coming up and one which is far more in line with the original summer forecast.

[mulzy]

Hats off to Gfs, it does get a lot of flack,but it has set the trend in recent days! No point fighting online as to which model is best! Anyway back to the models, and lots of heat and humidity for the south in the next week, then the north cental areas, plagued by that cold front...Looks as though some very thundery conditions developing later in the south by Thursday/Friday.....

What's there to fight about? The ECM is the gold standard as the verification stats show.

[PubliusEnigma]

OK this evenings Fax shows the prognosis for thursday. Friday is looking interesting. My take on

the most likely outcome would be as follows, and as per the illustration.

Hot still in the south, with a week ridge just to the north of the decaying stationary front over central

northern areas. Here cooler with cloud, possibly some scattered thunderstorms over the peaks and central england. A developing shortwave, will move smartly south east to position close to the south west peninsular. The decaying old front will merge with the approaching low, pushing a band of cloudy weather ahead of the approaching front associated with the LP. It will bring outbreaks of rain through northwest and central parts. The thundery low over Northern Spain will molst likely track NNE into central france with a lot of thundery activity here. And come the opening ceremony the storms will most likely just miss the south coast and remain the other side of the channel. A rogue thundery shower somewhere over the downs or generally east sussex or Kent can't be ruled out. However a veil of cloud from the cold front from the low now over SW parts will probably limit much vertical lift so there is a reasonable chance if the cold front remains far enough from the London area, that it could remain dry here, maybe even quite warm until the circulation from the shortwave mixes in cooler air over the British Isles.

What's there to fight about? The ECM is the gold standard as the verification stats show.

The GFS got it right, the ECM got it wrong, and is now falling into line with the GFS.

Edited July 21, 2012 by PubliusEnigma

[SP1986]

The GFS 18z is actually quite a good run.. althought apparently the 18z is not the most accurate run, it is in itself quite a decent run, in terms of warmth holding on over most of England and Wales. Also picks up on potential for isolated thunderstorm acitvity as the low pressure comes up against the warm, continental air.

The problem is that whilst the GFS outlook is now, not so bad, the ECM outlook is pretty dire, and one will have to give. However I would expect the ECM to tone down the extremity of the northerly. For what it's worth, I thought the 12z ECM run looked a little disjointed, can't put my finger on it but it lacked the fluidity in the evolution of the pattern.

[Snowy Easterly]

GFS is not too bad it stays warm all week over most of England and Wales http://cdn.nwstatic....4/ukmaxtemp.png

Then the thundery rain hits the South on Saturday, still subject to change though probably, but this run is fine by me if it comes off, better than the northerly crap that the UKMO and ECM show, lets hope they plays catch up again

Edited July 21, 2012 by Snowy Easterly

[bluearmy]

for those interested in throwing out plaudits, the GEM was the first op run to pick the pattern for the end of this week on its 00z run of the 17th. this model has a habit of picking out a change at 8 to 10 days range though it rarely sticks with it which makes it tough to take too much notice of these 'rogue' runs but similarly means you shouldn't ignore it when it does.

[johnholmes]

The GFS rainfall totals for the London area are 8 and 3mm with 3 for north of the Thames and 8 south of it. The 12z run showed 3 and 3mm.

It appears, whilst giving a similar overall idea, to have backed down on the 00z from the heavier outbreaks-not unusual and there will be further changes through the run up to T+00.

It would seem increasingly unlikely that the dry fairly clear evening and night initially predicted is going to occur.

The 500mb anomaly charts from ECMWF-GFS are missing this morning. The 12z issue from yesterday and ECMWF showed a marked trough over/just east of the UK with GFS still preferring a cut off 500mb low. So ECMWF has shifted more towards GFS than the other way round, the charts being valid for the end of July.

Edited July 22, 2012 by johnholmes

[chionomaniac]

Still big differences apparent in the type of troughing to affect us next weekend from the GFS and ECM. The T+168 GFS is still sticking with a cut off low, though this is deeper than previously modeled. The ECM has a super long, long wave trough from the Arctic. Just look at the isobar indicated, travelling from the Arctic to North Africa- and beyond!

GFS

ECM

I will be very happy if this is still showing in five months time!

[Uncle_Barty]

Hats off to Gfs, it does get a lot of flack,but it has set the trend in recent days! No point fighting online as to which model is best! Anyway back to the models, and lots of heat and humidity for the south in the next week, then the north cental areas, plagued by that cold front...Looks as though some very thundery conditions developing later in the south by Thursday/Friday.....

Or not, good call by Shedhead.

How can we say "hats off to GFS" etc, when we are still 5 days or more from the situation even starting to verify?????

[Kiwi]

for those interested in throwing out plaudits, the GEM was the first op run to pick the pattern for the end of this week on its 00z run of the 17th. this model has a habit of picking out a change at 8 to 10 days range though it rarely sticks with it which makes it tough to take too much notice of these 'rogue' runs but similarly means you shouldn't ignore it when it does.

This battle of the models always makes good interesting reading. The GFS does seem to have been fairly consistent on the coming set-up for the Olympic opening ceremony. The ECMWF has been the one playing catch up in my non-tech eyes.

Bluearmy points out that the GEM picked up on the pattern on the 17th. The GEM it seems is often overlooked as we focus on the GFS v ECM debates.

And what about our friend Piers, who is often dismissed out of hand ? ...he said this (taken from the Telegraph on the 16th!) “We’re very confident that there will be a lot of rain – a deluge, really – during the entire Olympic period, and we are 80 per cent sure that the Opening Ceremony itself will feature heavy rain, including hail and thunder.â€

What models/methods does Piers use? ...and can we get access to these? I'm sure they'd make interesting reading/debate

[mushymanrob]

the gfs did pick up on the developing trough long before the ecm, assuming this varifies then yes, hats off to the gfs for doing so and sticking with it...however... the gfs is still suggesting that this developing low will sit around us, close by, for most of the following week whilst the ecm has it drift eastwards by monday next. so atm, the gfs's insistance that there will be a developing low looks like being correct, but the important thing is what happens to it afterwards, because THATS what will influence our weather for the following week.

personally, forget the temps, ill settle for the driest option, im sick of the wet (working outdoors).

[bluearmy]

This battle of the models always makes good interesting reading. The GFS does seem to have been fairly consistent on the coming set-up for the Olympic opening ceremony. The ECMWF has been the one playing catch up in my non-tech eyes.

Bluearmy points out that the GEM picked up on the pattern on the 17th. The GEM it seems is often overlooked as we focus on the GFS v ECM debates.

And what about our friend Piers, who is often dismissed out of hand ? ...he said this (taken from the Telegraph on the 16th!) “We’re very confident that there will be a lot of rain – a deluge, really – during the entire Olympic period, and we are 80 per cent sure that the Opening Ceremony itself will feature heavy rain, including hail and thunder.â€

What models/methods does Piers use? ...and can we get access to these? I'm sure they'd make interesting reading/debate

i'm afraid piers wont reveal his technique to anyone kiwi. not really a problem cos he's wrong as often as he is right. shame about the language aswell - 'deluge' for two weeks ?? if he's right, given the level of groundwater, the sailing may as well take place in london !! regents park would be a good spot. btw, i dont think he will be right. (opening ceremony apart where he has a good shout and it was a good call on the 16th)

[ANYWEATHER]

How can we say "hats off to GFS" etc, when we are still 5 days or more from the situation even starting to verify?????

The point being, ecm has had a lot of playing catch-up as regards to the Gfs. Im pretty confident that Gfs has got this evolution correct, although out at this range any details IE, precipitation etc is not really worth taking too much notice of at the moment.!

[johnholmes]

latest musings on the predicted upper air pattern

Current model output (500mb versions) leads to little confidence in the upper pattern.

Best stab would be the wly not there and some kind of trough just east of UK with building heights to the west for end month/early august.

IF this does occur then we have gone from the long ensconced trough close by the UK to a wly flow and back to a trough/ridge set up for the UK in an unusually short space of time, around 7-8 days from the first dropping of the trough to its re-emergence again.

I have to say that does surprise me with the pattern shown a week ago, 3 major troughs around the northern hemisphere usually means only slow changes, sometimes as retrogression. It’s rare in my experience to see such marked changes over such a short space of time with this wave length.

Edited July 22, 2012 by johnholmes

[Methuselah]

This battle of the models always makes good interesting reading. The GFS does seem to have been fairly consistent on the coming set-up for the Olympic opening ceremony. The ECMWF has been the one playing catch up in my non-tech eyes.

Bluearmy points out that the GEM picked up on the pattern on the 17th. The GEM it seems is often overlooked as we focus on the GFS v ECM debates.

And what about our friend Piers, who is often dismissed out of hand ? ...he said this (taken from the Telegraph on the 16th!) “We’re very confident that there will be a lot of rain – a deluge, really – during the entire Olympic period, and we are 80 per cent sure that the Opening Ceremony itself will feature heavy rain, including hail and thunder.â€

What models/methods does Piers use? ...and can we get access to these? I'm sure they'd make interesting reading/debate

Piers just makes it up as he goes along, IMO...He's wrong more often than he's right, anyway, so why would anyone consider his 'forecasts' to be a viable alternative to the models?

[Bobby]

The NAEFS signals high pressure slowly migrating back to Greenland with troughing back over us from later next week and into early August, looks like the same old pattern we've had since April.

+168

+274

Starting the second week of August

The best hope is that the high pressure sticks around in the N. Atlantic instead of going to Greenland which should at least allow for some settled weather from time to time.

Edited July 22, 2012 by Barb-

[TonyH]

Improved prospects at long last, perhaps not in the longer term for the start of the Olympics though:

http://forum.netweather.tv/blog/309/entry-4439-weather-guide-monday-23rd-to-sunday-29th-july-2012-west-wales-and-central-midlands/

[summer blizzard]

http://62.89.145.4/gefs/gefsens850London0.png

Ensembles say it all really, a couple of days of warmth and sunshine for England followed by average/below average type weather (though i suspect more northerly than Channel low types).

[mushymanrob]

....and the 06z gfs caves in and now supports the ecm's version of the next weekends troughs departure, drifting to our east allowing in a cool northerly.

hats off to the ecm? (assuming this scenario varifies)

[Frosty.]

The ecm 00z again shows high pressure building from the south later in FI but a breakdown to the hot and sunny weather in the south seems inevitable with either homegrown thundery showers or storms drifting up from northern france towards the southeast on fri/sat, then cooler and more unsettled briefly before high pressure begins to regain control. In the meantime, northern britain improving but a persistent front across the middle of the uk will be a nuicance with occasional rain along it and a lot of cloud with the clearer skies and hot sunshine across southern areas, especially hot in london midweek at 31c 88f, maybe even 32c before the storms or heavy showers wash away the heat.

[johnholmes]

....and the 06z gfs caves in and now supports the ecm's version of the next weekends troughs departure, drifting to our east allowing in a cool northerly.

hats off to the ecm? (assuming this scenario varifies)

mushy how do you arrive at that comment please?

the precip chart (okay pretty useless I know this far out but just comparing run to run) the 06z has got much more rainfall accumulation in the London area than the 00z showed?

Edited July 22, 2012 by johnholmes

[mushymanrob]

mushy how do you arrive at that comment please?

the precip chart (okay pretty useless I know this far out but just comparing run to run) the 06z has got much more rainfall accumulation in the London area than the 00z showed?

the gfs has consistently shown this developing area of low pressure sitting over us, even being locked in by ridges of high pressure to our north joining the azh and continental hp. the ecm has been suggesting an earlier exit to our east.... the 06z gfs now supports the ecm, dropping the 'locked in' low it had previously shown.

[Evening thunder]

http://62.89.145.4/g...s850London0.png

Ensembles say it all really, a couple of days of warmth and sunshine for England followed by average/below average type weather (though i suspect more northerly than Channel low types).

I count about 6 days going by those ensembles, though yes after that look average/below average.

[Bobby]

I think it's more it merges with the trough over Scandinavia than clearing east. GFS 06z shows 4 days of heavy rain/showers Friday-Tuesday

Some cold air being dragged down from the North too, one chilly chart for 1st August

Edited July 22, 2012 by Barb-