Model Output Discussion 18z 28/07/13

[Methuselah]

Sorry i dont know why my above post has mixed with JH post.I quoted correctly but my reply has tagged on to his!.

It was the closing bracket, mate!

[Frosty.]

The Ecm 00z ensemble mean shows an impressive continental hot plume drifting north from france, enabled by a trough anchored to the southwest of the uk which slowly fills and drifts away north by northeast with pressure then building from the south, the outlook shows a warm and humid slack pattern with a lot of dry and sunny weather but with an ongoing risk of heavy, slow moving thundery showers breaking out at times. As for the incoming hot plume, temperatures are set to rise across the southern half of the uk by wednesday and then rocket into the low to mid 80's with high 80's to low 90's for parts of the south & east, a stormy breakdown looks likely but then turning fine and sunny with temperatures in the mid 20's celsius, there is nothing cool on the charts for the uk at all, temperatures never look worse than average and generally above or well above, tomorrow looks the freshest feeling day of the week with 19-22 celsius being the range across the board with rain across the south and sunshine & showers elsewhere but temperatures then on the rise, along with the humidity levels behind an active warm front pushing north during midweek with a band of heavy rain, it's likely to become hot and sultry for central, southern and eastern areas on thurs/fri/sat with the hot uppers only slowly easing away and remaining close to the south/southeast thereafter.

Edited July 29, 2013 by Frosty039

[joggs]

It was the closing bracket, mate!

Oh yes,cheers abns

[stainesbloke]

New month...same weather? Temps on the up again...Hard to believe to be honest, what with so many let down Summers we've had - a mixture to please pretty much everyone too.Wow

Yes, what a turnaround from the last 6 awful summers. Hallelujah! Some more heat to come later this week, the possibility of some strong thunderstorms and indications of high pressure building in next week. Details still to reveal themselves but I'm more than satisfied.

[Lincstim]

Please don't say thunderstorms and heavy rain for north lincs for Saturday

Local music festival happening

[shedhead]

New month...same weather? Temps on the up again...Hard to believe to be honest, what with so many let down Summers we've had - a mixture to please pretty much everyone too.Wow

 

Not sure this is an accurate discription of things to come as we move into Aug, though I also note your opening sentance was a question.  The overall pattern for the next 5 or 6 days is rather unsettled, though clearly not to any great degree, with a brief warm/very warm plume to come for many and a hot one for some later this week. Across the weekend and into next week there is a signal for rising pressure, especially across the north, but conditions still look a long way from the lengthy heatwave that domimated much of this month.   

 

No saying we won't get back there, but for now things remain quite a bit different.

Edited July 29, 2013 by shedhead

[William of Walworth]

I'm keeping an eye on that large area of High Pressure shown to the UK's SW on the later frames of Frosty's post. Hard to be sure yet how strongly? that might build towards us in FI but IF it were to do so, prospects for early, August, maybe for mid August too, could become very pleasant and summery. That would please many, including me who likes warm and settled more than hot and unstable/stormy.

 

Taking on board what shed has just said as well, as he correctly says nothing's nailed on yet.

 

I'm also taking notice too of john's warning that the anomoly charts allow different evolutions to be possible. And as he says, once you get into August, ex-hurricanes often render everything unpredictable in Atlanticland.

Edited July 29, 2013 by William of Walworth

[DTHFCJ]

I am slowly getting a few folk to at least look at them. Without wanting to sound as if I am talking down to anyone, I am thinking of trying to do a post explaining how to use them, when they give good guidance, when not, what they actually show etc?

 

In terms of the current output they are fairly different as I've posted earlier today. The next thing tp put a spanner in the model works will be if the hurricane season really gets going next month and onwards. In spite of different models being quite good at both predicting their track and development or non development into the Caribbean or Gulf of Mexico, they are less good once these things get into the Atlantic. The huge amounts of vapour involved must have something to do with it I feel and the very large changes in heat content as they change from tropical-hurricane-ex storms and transfer into the less warm sea areas, and the colder air the further north they get. Interesting though as most things meteorological are.

John that would be a very good idea ref an explanation of how to use them......

 

courtesy of Snowking(hope you dont mind Snowking me re posting this).......who posted this 29 June....

Might be a good idea just to do a quick illustration to clear this one up (I do understand it is confusing with the difference between heights and SLP - getting your head around the different pressure layers of the troposphere is one of the most tricky things to do, but its essential for more expansive forecasting)

 

So, heres a couple of basics, the sort of things that I used to take a look at when I only had a chance to glance quickly at the models. I have made some markings on the below image - the latest height anomaly projection from the ECMWF

 

 

As John has said, ignore the colours for now - follow the lines! (Again its tricky to get your head around, but don't automatically assume that the higher heights (reds) will always lead to high pressure, and vice versa with blues). By the lines, we are talking about the "horizontal" black lines, which are indicated by the green arrows drawn.

 

If anyone can think back to GCSE Maths (or possibly even physics), think of these in terms of a Sine wave. When they point up, they are a peak (or in meteorological terms, a ridge) and when they point down, they are a trough.

 

You might have heard that term trough used a fair bit on here - ridges and troughs are what make up the Longwave Pattern across the Northern (and Southern - though we rarely focus on this) hemisphere. By this, we mean that the weather all around the globe follows a series of ridges (areas of high pressure) and troughs (areas of low pressure).

 

We can identify such areas on the annotated chart above. I have shown a ridge (in the blue box) forecast across the UK - taken in current context, in around 8-10 days time, the current ECMWF suggestion is of ridging across the UK. How can we tell it is a ridge? Because those black bars are pointing towards the north pole.

 

I have also identified a trough (in the yellow box), which would indicate an area of 'troughing' - essentially, an area (or collection) of low pressure. We can tell its a trough because the black lines are facing towards the equator.

 

So, its a case of looking for ridges (black lines facing poleward) for the chance of more settled conditions, and troughs (black lines facing equator-ward) for unsettled conditions. 

 

It gets a lot more complex than that - we can start looking for closed ridges/troughs, and in the winter, we also look at certain colours of the black lines indicating where the 528DAM line (considered a good measure of the 'snow line' under most circumstances) is. But we'll worry about that another day.

 

In the meantime, when looking at height anomaly charts, look for ridges for potential settled spells, and troughs for potential unsettled spells, in the vicinity of the UK

 

thanks to Snowking

[johnholmes]

re the above post

I will be incorporating much of what SK posted when I get round to doing this.

[WheresTheSnow]

Although the 06Z might not be showing temperatures as high as they were showing on previous output  for Thursday/Friday, I still believe it is a good run as the warm/hot temperatures are maintained for the Central Belt of the UK, as well as the SE until Monday - with temperatures at or above 25C Thursday onwards.

 

Hot for most of England, and Wales, with Scotland and Ireland remaining on the cooler side.

The heat then dies away for areas further to the west, with areas further to the East hanging onto the warm temperatures. Sunday is similar with maxes of 25c for areas further to the East.

By Monday, the +10 850hpa temp starts build again from the SE, producing higher temperatures on a more broader scale Monday, but still with Ireland, Scotland and the NW missing out:

 

All in all, I am happy with that run. Temperatures are not too hot, but comfortable to be able to do things in, perfect. Not a bad Summer if it carries on this way!

[Man With Beard]

Many ensemble members on GFS 06Z go for another warm-up next week

 

http://modeles.meteociel.fr/modeles/gens/graphe_ens3.php?x=306&ext=1&y=141&run=6&ville=Londres&runpara=0 

[shedhead]

Not strictly model related, but interesting nonetheless that the latest MO update does not reflect the pressure rise towards the north shown by GFS and ECM, indeed their forecasts suggests the opposite. The plot thickens...

 

UK Outlook for Saturday 3 Aug 2013 to Monday 12 Aug 2013:

This coming weekend, any thundery showers in the east should clear during Saturday, otherwise, generally unsettled with bands of rain or showers affecting many areas, but some sunshine as well. Showers could be heavy, mainly towards the northwest, while southern and eastern areas should see the best of the drier, brighter weather. Breezy, especially in the northwest, where temperatures will be near normal, but warm elsewhere. Into the start of next week, the unsettled theme will probably continue, with a risk of rain or showers in many areas, perhaps thundery at times. There is, however, an increasing chance of more prolonged drier, warmer spells for a time next week, particularly in the south and southeast. Many places could then become noticeably cooler later next week and into the following weekend.

Updated: 1203 on Mon 29 Jul 2013

[forecaster]

The Thursday warm spell looks disappointing according to GFS 06Z run back trajectories, which show a maritime airmass in contrast to last Monday's event, which was a much lighter continental drift.

The descent and final period over the continent should be helpful for warming though.

 

 

 

 

[johnholmes]

an interesting piece of info there forecaster-useful to know that, I had that bookmarked some time ago but have lost it

[johnholmes]

John, which of the ECM-GFS 8 to 10 day charts would you advise using, the 0z or the 12z, which one is more accurate? Or does it not matter as long as you always use the same time of run, i.e. always 0z or always 12z with no mix and match, as per the standard models?

 

I don't think it matters, for convenience I have always taken the 00z ec-gfs and the noaa 12z which tends to disagree with my oft given advice to use the same time runs each day!

Mind you as the anomaly charts are usually slow to make marked changes I think it matters less than with the 2x or 4x daily synoptic ouputs.

[Frosty.]

I like the look of the GEFS 06z mean within the T+240 hours timeframe, first we get the hot continental plume and then high pressure builds in from next weekend and well into the following week before pressure falls slightly and the pattern looks very slack next week which probably translates to a lot of fine and sunny weather with light winds and on the warm side but also a risk of scattered heavy, slow moving thundery showers from around the middle of next week after a more settled spell. The next few days look rather mixed, temperatures tomorrow will be about as cool as they are likely to get for some time, 20c 68f being a typical max temp tomorrow with a spell of rain across the south which will only slowly clear into the english channel and a rash of showers for most other areas along with sunny spells and a brisk wsw'ly breeze but then midweek heralds the much anticipated marked change as an active warm front sweeps north across the uk with a mass of heavy rain associated with it but behind the front, the winds back S'ly to SE'ly with a big injection of continental heat & humidity, by thursday the temperatures between 28-31 celsius and closer to 32-33c in the east/se on friday, with those very high temperatures and sultry conditions comes a risk of scattered big storms and also a line of storms along the advancing cold front from the west as it pushes into the hot sticky airmass, but then high pressure builds from the southeast and spreads the fine weather further north and west, once we lose the hot uppers, it remains on the warm side and next week could become warmer again and more humid with that risk of showers growing once again, a lot to keep an eye on during the next 7-10 days for sure.

 

PS..I like the new BBC lightning detector, it's very striking.

[shedhead]

The Thursday warm spell looks disappointing according to GFS 06Z run back trajectories, which show a maritime airmass in contrast to last Monday's event, which was a much lighter continental drift.

The descent and final period over the continent should be helpful for warming though.

 

 

Thanks for that forecaster. 

 

The local BBC output is only calling for 21-23c here on Thurs under a good deal of cloud and although the MO are talking about a localised 30c in the east it's pretty clear they are keeping their feet rather more firmly on the ground than some.

 

GFS have brought expected max down by at least a degree across the last 2 or 3 runs, so it will be interesting to see whether the 12's arrests or maintains this trend.

Edited July 29, 2013 by shedhead

[Cecil Hogmanay Melchett]

One has to say the outlook looks pretty damn fine by and large with the ecm and the gfs both promoting pressure build as we head through the weekend.Both models keen to send the PFJ north allowing a more settled spell (if not massively hot),as per norm the further Sand E looks better but all in all a very useable spell of summer weather looks odds on as we head though the first week of August.

06GFS ensembles look very warm for London with the mean well above average generally.

Edited July 29, 2013 by happy days

[shedhead]

NAE continues to go for some decent totals across the south tomorrow, but not a lot progged north of the M4 corridor.

 

 

 

 

 

 

 

Edited July 29, 2013 by shedhead

[Captain Shortwave]

Stronger ridging north on this run from the GFS

 

 

Warmer day on Friday now compared to recent runs, oddly the temperatures are a little lower on Thursday (29C instead of 31C), but that's probably due to other factors (forecast cloud cover etc)

Breakdown Friday night into Saturday

Edited July 29, 2013 by Captain shortwave

[shaky]

Much better gfs 12z so far!!heat lasts longer and high pressure builds straight in after that keeping temps into the mid twenties!!i really do think we are heading in for a very special august and therefore our summer in general could be a very special one after so many years!!

[Captain Shortwave]

Get in the initial build and the heat just reloads

 

 

Heat pushing north again

Atlantic train? More like derailed buffet cart 

Edited July 29, 2013 by Captain shortwave

[pandit-scholar]

Despite the medium and long range models previously showing a break down to wet and cooler weather, the main models have consistently shown this not to be absolutely the case with another possible heat reload nearer the time!

[Tim Bland]

Plenty of heat and storms from the GFS 12z to keep us going. Storm wise today has been much better than forecast. Fingers crossed this warm or thundery weather lasts until Nov! Then the snow watch can start

http://www.meteociel.fr/modeles/gfse_cartes.php?&ech=216&mode=11

[Captain Shortwave]

GEM still wants to push the 20C isotherm over the south east