Model Output Discussion 22/07/12 Onwards.

[William of Walworth]

I take your point, about Augusts tending not to deliver in recent years, but it's speculation to say the least to forget any hope of more heat given that we haven't even reached 1st August yet ...

Right now, with all due FI caveats added, I think some of the current trends for next month, uncertain as they are, are starting to look reasonably positive.

Not for next week I accept (Frosty's posts are suitably reaslitic there). But some of the longer term signals MAY be hinting at more summerlike, or starting to. FI is FI but some of the synoptic and more technical MJO type trends (such as those GP was mentioning) do seem to look better, and I do like the suggestions -- only suggestions so far -- of possible weakening of Northern/Greenland blocking later on, and fragmentation/northward movement of jet. Us sumemr preferrers can dream!

Lets hope anyway that these ideas start to get confirmed over future days -- but in no way can we write off August yet. And the switches and changes in the recent operationals should offer a cautionary note to pessimists, given how negative some of them looked as recently as a day or two ago ...

Plus the non-synoptic/non-meteorological idea (mine, and hopecasting) that we are DUE a less wet/less unsettled August after our largely dreadful June and July!

Edited July 24, 2012 by William of Walworth

[Bristawl Si]

Seems like latest model output means things shouldn't be all doom and gloom for August as some were posting on here a day or so ago.

I'll stick to my forecast of a couple of days ago, for next week, as sunshine and showers and about normal temps, esp for the south.

[johnholmes]

thought this might be of interest in here after dropping it into the Olympic thread

Met O Fax charts for 12z Friday

Currently if you are quick you can see 3 of these, including one given T+84 and time of issue 0608 this morning which I had not seen before, the latest one has date stamp of 1747 today.

Each subsequent one has shifted/amalgamated the cold front as it moves towards the London area.

This latest one has it almost on to London with a gradient about NW which would help to move it east I would expect. It might be that they are now expecting the cold front to clear the Olympic site before the opening ceremony begins.

Interesting to compare the 3 charts though.

link below

http://www.weathercharts.org/ukmomslp.htm#t60

Edited July 24, 2012 by johnholmes

[damianslaw]

The short term outlook is very much a north-south divide. The south should hold onto very warm/hot conditions until Friday, central parts will continue to be troubled by the ever troublesome front which looks like pepping up on Thursday to bring further rain to some parts, however, by Friday we will begin to a more pronounced change from the north as we see a cold front sweeping southwards with marked temp drop as it clears many southern parts.

Weekend - all models are showing a rather cool showery affair under a chilly northerly airflow. NE parts look like seeing the most showery activity, but anywhere could catch some hefty downpours, but in any dry parts, plenty of sunshine should occur, but temps back to average if not a bit below in northern parts.

As we end the month and start August, there is a lot of consistency in the models today, both ECM and GFS hold onto strong mid atlantic heights and the maintenance of a rather cool showery airstream but no washout.

Longer term - lots of mixed signals, but early August isn't renowned for major pattern changes, however, perhaps we might see similiar synoptics to now, with the jet tracking further north to bring the traditional NW-SE divide, good news for the SE, but not the NW.. as the last three days have witnessed - its been poor in the Lake District, no sunshine, low cloud and that fine drizzly rain just dampening everything and adding to the gloom.

[Glacier Point]

I hope you'll note 00z ECM and GEM trending day 7 onwards, as well as GEFS slightly later days 10 onwards.

That cut off upper low shifting its mean position west and south over time, allowing for a draw up of warmer uppers over Europe as the sub-tropical ridge shifts its position westwards in the Atlantic.

2nd week August definately looking better, and next week a little mixed but still lots of uncertainty given issues modelling shortwaves cutting south of Greenland, which has direct implications for shower activity and more organised rain bands.

Edited July 25, 2012 by Glacier Point

[Alex]

I hope you'll note 00z ECM and GEM trending day 7 onwards, as well as GEFS slightly later days 10 onwards.

That cut off upper low shifting its mean position west and south over time, allowing for a draw up of warmer uppers over Europe as the sub-tropical ridge shifts its position westwards in the Atlantic.

2nd week August definately looking better, and next week a little mixed but still lots of uncertainty given issues modelling shortwaves cutting south of Greenland, which has direct implications for shower activity and more organised rain bands.

I did see this trend, very interesting and well supported by the teleconnections. I couldn't think of many times this had happened but looking much better. I wonder if a further increase in angular momentum could accelerate this process?

[BLAST FROM THE PAST]

Any change will be slow, as indeed the signs ten days ago of a 'westerly' flow did not materialise. The tentative signs that ECM show of trough moving in position a la GP would indeed bring summer to our shores. What we don't want is for the trough to anchor itself over us. IMO the jetstream pattern remains in a situation that helps/promotes longevity in synoptic set ups. Fingers crossed then for the shifting of the trough s and w of the UK and Ireland.

BFTP

[NorthNorfolkWeather]

I hope you'll note 00z ECM and GEM trending day 7 onwards, as well as GEFS slightly later days 10 onwards.

That cut off upper low shifting its mean position west and south over time, allowing for a draw up of warmer uppers over Europe as the sub-tropical ridge shifts its position westwards in the Atlantic.

2nd week August definately looking better, and next week a little mixed but still lots of uncertainty given issues modelling shortwaves cutting south of Greenland, which has direct implications for shower activity and more organised rain bands.

I see that the GFS is having little to do with any retrogression. It seems that it (GFS) is still struggling with the recent variations in angular momentum

[johnholmes]

I hope you'll note 00z ECM and GEM trending day 7 onwards, as well as GEFS slightly later days 10 onwards.

That cut off upper low shifting its mean position west and south over time, allowing for a draw up of warmer uppers over Europe as the sub-tropical ridge shifts its position westwards in the Atlantic.

2nd week August definately looking better, and next week a little mixed but still lots of uncertainty given issues modelling shortwaves cutting south of Greenland, which has direct implications for shower activity and more organised rain bands.

yes I noted this morning that the 500mb anomaly charts both show the cut off low being further west than they have suggested previously. Time will tell if its another hiccup or a change in 500 flow over the UK. If it is a change in flow then as you suggest Stewart a warmer spell would be the likely outcome, for how long is hard to say. I am quite surprised just how many changes are being predicted on the 500 charts in the past 2-3 weeks. So many changes in such a short time do seem quite unusual to me.

[Glacier Point]

Indeed John, the ensemble mean height anomalies have been generally well defined, but moving from one position to another on a daily basis of late within the Atlantic sector.

[shedhead]

Encouraging yes, but all the potential changes for the better being talked about are a long way off. In the shorter/more reliable timeframe it's still looking very much like a return to business as usual, with all the main players making LP the dominant feature for some considerable time, especially the rather more reliable/consistent GFS. ECM does indeed offer some glimmer of hope, but for my money it's no more than a glimmer right now and is not something I'm going to get too exited about.

[Methuselah]

Who was it who said that the progged 32C temps were 'impossible', due to the soil being wet? Do't the models take all that into account?

[Bobby]

There does seem to be a trend to put the trough more to our SW but that might mean it only gets wetter as warm moist tropical maritime air gets pumped up, for here anyway, though places further N and E might not be too bad.

Unless it clears off way to our SW, we'll see.

NAEFS +192 = wet

[phil nw.]

Well it does look like this very warm- and for many- sunny spell will finish by the end of the week as a low comes down from the north west.

This fax shows the cooler air coming in behind the front bringing showery rain through with it clearing the far south east overnight friday.

Temperatures will fall much closer to or slighlty below normal for mid-Summer with some showers and sunny intervals as the cut off upper trough becomes stationary around the north of the UK.

The UK T144hrs-fairly typical of the 00z`s modelling.

The south east would likely be favoured for longer drier periods in this slack south westerly flow with the tendency for some ridging over the near continent from the displaced Azores High.

It must be said detail from day to day is difficult to pin down at this stage but nowhere can be guaranteed a completely dry day.

The 00z GFS Ens for London pretty much sums up the outlook here as we go into August.

The mean(white)line on the rain graph is quite low.So a decent outlook for the start of the Olympics- the doubt is whether the opening ceromony itself can escape that rain coming through Friday evening- it`s touch and go at the moment.

Just a glance at the period up to the end of next week around day 10 and here are the images of the ECM/GFS ens 500hPa mean height anomls.

These show little change with troughing around the UK wedged between the upper heights around the Canadian Maritimes and Western Russia leaving us in the sunshine and showers regime.

In summary then the warmth and sunshine giving way to cooler weather with some showers,particularly in the more northern and western areas by the weekend and going into next week.Not all doom and gloom though with some sunshine at times but feeling much fresher than currently.

Edited July 25, 2012 by phil n.warks.

[Bobby]

GFS 06z looks unsettled into August. Tuesday looks especially wet after a few showery days

Edited July 25, 2012 by Barb-

[legritter]

Afternoon all. We are now much closer to the weekend but still exact synoptic situation a bit unclear. Going by latest models data etc, I personally think Friday during the day will be hit and miss regards any potential rain, showers and the intensity of any storms etc - dependent on that front slipping south east with the strength of the front being important and the speed that it comes through. At this range aprox 48/54 hrs away from now, if it travels 2/4 miles per hour at a different spead to current predictions that could be a difference of 150/ 200miles, so to put todays forecast in perspective any forecaster making a forecast today will I'm sure in their professional job, be very care full with what they publish even at this fairly close range .

GFS showing plenty of action for next week, ECM and Met etc all giving broad agreement Could be a very wet period late mon till Thurs, at the moment i cannot see any shifting of weather systems untill the jet fires up again - only mother nature can. But probably all that information is up there but we are not yet knowlegable enough . only time will bring that as my post yesterday for new, young and older posters just learning the ropes I mentioned contrails. If you look today, the contrails seem a bit longer and last that much longer. Upper air becoming slightly more favourable by tomorrow and Friday maybe even longer. Don't forget its a good thing to read and will help you understand upper atmosphere. Don't forget to look at Met fax as i find these very interesting. How to read into these can be found on Netweather site .

Cheers legritter

[legritter]

If there are any new learners out there, go to SAT 24 and type in Europe. You can get a birds eye view of current conditions. Compare this to current chart and you can see the different air masses and which way they are moving, then this evening about 8pm have another look and you will notice where any convection is. The sun a couple of hours from sundown catches these features at a good angle.

When you become more experienced you can then get a picture in your mind for what it will look like in a further 24 hrs or so Currently waiting for GFS update, I'm half expecting any rain in south and central parts to arrive a bit sooner now as of what was predicted. Severall parcels of air now making it further into the atmosphere, but satellite will not pick these up, as its small fry compared to a cloud that is more developed through uplift into mid upper atmosphere. Enjoy the current heatwave

[Alex]

Interesting that the ensembles for the MJO on the GFS output want to pull the mjo away from phase 5 where the ECM ensembles want to keep it weak at phases 3-4-5. I wonder whether the ECM will follow the MET models output this evening in pushing that trough further north and west compared to the GFS for next week?

Edited July 25, 2012 by Alex

[Summer Sun]

Lovely end to GFS shame its FI

Temps would widely be in he 20's if it came off

Edited July 25, 2012 by Summer Sun

[Weather Wizard]

GP's scandinavian high showing up towards the end of the GFS

and at 144h the UKMO looks pretty warm

Edited July 25, 2012 by Weather wizard

[WheresTheSnow]

Although the model output is not as good for next week, BBC are showing temps of around low to mid 20's all of next week, although it will be more cloudy, with more rain, that doesnt seem too bad ?

Those charts above looks good, I will be praying they come off!

Edited July 25, 2012 by WheresTheSnow

[OldMetMan]

Quite a variation today in model output, but the thing that caught my eye in particular is how the UKMet FAX has slowed the SE progress of the cold front for Thursday/Friday, thus the heat will linger a bit longer over Kent/Essex. If that happens, it would also allow more opportunity for either heat storms or convergence lines of storms to form ahead of the front.

Looking at the developing upper flow over and to the W of the UK, the sharpening upper trough seems to be developing quickly as is the upstream upper low near Newfoundland, as can be seen clearly in this WV satellite loop:

http://www.ssd.noaa....l/flash-wv.html

Note also a large area of moisture moving out of Spain, associated with a significant thunderstorm outbreak, so I would not be surprised to see medium-level storms S and SW of the upper trough forming by tomorrow and tracking our way.

The broader and longer term view does show, as I said, some variation but there is a reasonable consensus for the short- to mid-term with an upper low very close to the UK. The GEM goes a bit weird with the main LP sitting to the SW and deepening but overall it seems mostly a mobile longer term, although pressure may remain high-ish over the south.

Edited July 25, 2012 by OldMetMan

[legritter]

yes certainly an area to keep an eye on later tomorrow ,france and our s/sw , but tomorrows charts will be eagerly awaited . im still sat on the fence a little but intersting modell watching coming up . and that looks like extending into next week . what awaits us weather enthusiasts . radar will play a big part im sure with things popping up quickly . just waiting for ECM to update ,will go and check cheers

[Summer Sun]

After a big drop this weekend temperatures slowly recover as we move into August and it turns drier as well

Another low en-route for next week

Edited July 25, 2012 by Summer Sun

[Cloud 10]

Weird synoptic charts of the day goes to the 12z GFS with a low forming over southern Scandinavia

at +132 which then heads west and deepens dramatically to sit just NE of Scotland at day 7.