Model Output Discussion 14th May 2012 Onwards

[Cheese Rice]

The bank holiday weekend looks awful, you can't put it any other way.

Persistent drizzle of the north sea, cool winds and suppressed temperatures.

YUCK!

[samadamsuk]

Some parts of Scotland saw 27oC over the weekend.. A drop to nearer 10oC will feel Brrrrrrrr.... Overtones to the end or March.. Wonder If June will be a repeat of April ?

Hi PE

It's definately a worry I'd say. Starting to get suspicious that the dice are loaded after 5 years of almost constant summer troughing!

[William of Walworth]

Hi PE

It's definately a worry I'd say. Starting to get suspicious that the dice are loaded after 5 years of almost constant summer troughing!

I'd be suspicious of that too, being something of a pessimist and low expectations type when it comes to summers.

BUT what I'm also aware of is this : Allowing yourself to base your thoughts on what this summer could be like on recent sumer precedent and assuming repeats are overwhelmingly more likely than differences, is a recipe for paranoia rather than meteorology!

Edited May 29, 2012 by William of Walworth

[William of Walworth]

Its not nonsense at all, under cloudy skies temperatures will be very suppressed. 13/14.c widespread under cloudy conditions seems appropriate, warmer in UHE for obvious reasons. Under any sunshine temperatures rising to 17/18.c, most likely across SW England/Wales/NW England and Southern Ireland.

A quick peek at the BBC forecast shows a max for Saturday at-

Newcastle: 11.c

Leeds: 13.c

Norwhich : 13.c

Cambridgeshire: 13.c

Birmingham : 14.c

London: 16.c

Apart from Newcastle all the places listed have similar year round temperature profiles.

Those temps still look a tad undercooked to me, even given the current quite discouraging output for the upcoming w/e.

[Uncle_Barty]

Not liking the look of the output at the moment - looking increasingly unsettled as next week progresses as the enemy of decent summers in the UK - the Greenland Block - starts to look increasingly limpet-like.

A little way off, so time for things to change on that score, but a darkening feeling of deja-vu here.....

[shedhead]

We're pretty used to listening to the 'Winter's over before it starts' soothsayers, but those who frequent the MDT across all seasons and all weathers can normally be relied upon to be a little less melodramatic! OK things are set to go downhill bigtime regarding temps across the rest of this week and yes the holiday weekend does look cool/very cool and a little unsettled, but even come the end of it we'll still be in the week 1 of a 13 week Summer. Again I know it's tempting to assume the pattern will set up much as across the last 3 or 4 summers, especially as the northern blocking seems determined to remain in place, but as the last week or so has shown things can change both quickly and dramatically.

Edited May 29, 2012 by shedhead

[Roadrunner]

We're pretty used to listening to the 'Winter's over before it starts' soothsayers, but those who frequent the MDT across all seasons and all weathers can normally be relied upon to be a little less melodramatic! OK things are set to go downhill bigtime regarding temps across the rest of this week and yes the holiday weekend does look cool/very cool and a little unsettled, but even come the end of it we'll still be in the week 1 of a 13 week Summer. Again I know it's tempting to assume the pattern will set up much as across the last 3 or 4 summers, especially as the northern blocking seems determined to remain in place, but as the last week or so has shown things can change both quickly and dramatically.

Very sensible and accurate post this one. Things are rarely as bad as they are predicted and modelled from my limited experience.

[Methuselah]

And, as we should all know, Britain's weather is characterized entirely by its pattern-changes...

[Summer Sun]

Both GFS and ECM paint an unsettled picture into June

http://www.null/ds/gfs.htm

http://www.null/ds/ecm.htm

UKMO soon follows

http://www.null/ds/ukmo.htm

[Weather Boy]

I'm not really getting this panic and alarm about BH weather.

As someone who's going to be abroad, I have no axe to grind. To me the forecast for the weekend looks cool but nothing exceptional. The GFS is much colder than the ECM. If the latter were to verify then there is no real northerly outbreak at all and I would expect around average temps. But it doesn't seem to me to be all that unsettled. The pressure overall seems too high to generate much in the way of showers and there aren't troublesome frontal systems about to speak of. The northern half of Scotland I would expect to be unsettled, if you take the GFS at least.

Maybe I am guilty of just picking up one run (the 0z) and running with it, whereas others are discussion earlier runs, but to me the coming weekend seems to be panning out as more average than poor, although I suppose that is disappointing after what we have had.

[Evening thunder]

Both GFS and ECM paint an unsettled picture into June

http://www.jp2webdes...o.uk/ds/gfs.htm

http://www.jp2webdes...o.uk/ds/ecm.htm

UKMO soon follows

http://www.jp2webdes....uk/ds/ukmo.htm

2 of those show more of a SE flow across the south at least this weekend, and a ridge across the rest. Not so much of this northerly a few seem to think means June's over in terms of summer weather then? The GFS shows more of a northerly (but it doesn't last forever and you've got to expect some below average temps as well as above average temps).

Yes some then show low pressure moving in in FI but it wouldn't be that cold with more SW winds, and it's starting to dry out a bit here again we could do with a bit of rain for a top-up.

Edited May 29, 2012 by Stormmad26

[TonyH]

The stark cool down for the weekend appearing less likely now at least for central and western areas and going by ECM and UKMO. Ridge over as opposed to west of us so we do not get the NE winds in the west at least.

Then early next week an Atlantic low looks set to bring up warm humid south-westerlies, thundery perhaps?

All in all typical Summer weather coming up.

[tinybill]

http://www.meteociel.fr/modeles/gfse_cartes.php?mode=2&ech=6

as some else has said the weather is looking yuk from now to at least june 14 !!!

[shedhead]

http://www.meteociel...hp?mode=2&ech=6

as some else has said the weather is looking yuk from now to at least june 14 !!!

With respect that simply isn't the case. April's weather was yuk, what's projected for us through until mid June may not be everyones idea of high Summer, but it a-typical British Summer and as such is not that bad overall.

[Derp Patrol]

The stark cool down for the weekend appearing less likely now at least for central and western areas and going by ECM and UKMO. Ridge over as opposed to west of us so we do not get the NE winds in the west at least.

Then early next week an Atlantic low looks set to bring up warm humid south-westerlies, thundery perhaps?

All in all typical Summer weather coming up.

yes, the charts aren't looking awful. There has been a trend recently for higher pressure over the UK this weekend and beyond, so it won't be as cool as some are thinking. Beyond this weekend is very much FI at the moment

[Scorcher]

http://www.meteociel...hp?mode=2&ech=6

as some else has said the weather is looking yuk from now to at least june 14 !!!

Yet another poster who only seems to appear when unsettled, cool conditions arrive. On what grounds do you base your assertion than it will be poor until June 14th? There is a reason why it's called FI!

[BlueHedgehog074]

Useful video by Gavin P (check out his site for his latest vids: http://gavsweathervids.com/) about the models for the next two weeks. Plus today's and tomorrow's thundery potential. Indeed, as is shown on the models, such as the 0Z ECMWF, those Lows out to the West seem eager to spring back into action increasing the chanes of disturbed weather for most (though changes regarding the Lows' positions could still occur).

[MP-R]

Well this is the first model run I've seen where the Atlantic train kicks into gear... from the northeast of all places so I will reserve judgement until I've seen more runs. It's definitely going to get cooler but it doesn't look overly wet apart from where thunderstorms and torrential showers break out.

Until today, the GFS was keen on bringing high pressure back to the south pretty quickly during the first week of June with lows spinning off to the northeast of Scotland, warm uppers bringing a return to warm and possibly quite humid conditions, only on this run has the effect of lows been brought a lot further south. I don't buy the idea of a return to April's weather in June - rather I think this weather we've just had is a precursor of a change in pattern. Though time will tell of course.

[phil nw.]

I think there is too much pessimism wrt the model output by a few posters.

Indeed we are going to cool down during the rest of the week with onset of a cooler North Easterly flow and with some cloud and showers.

However because we have some heights over Greenland now it doesn`t mean they are going to adversly affect our weather for the foreseeable as one or two posts are hinting at.

The medium term outputs suggest retrogression of Greenland heights further to the West and a reallignment of the Scandi. troughing to sit more West to East to our North as we enter week 2.

Here the 8-14 day 500hPa chart and GFS/ECM Op. around days 7-8.

All suggest a more normal reversion to a warmer South Westerly flow as we get into next week.

As a general overview- yes we are approaching a less warm and settled few days, with showers around but there`s nothing to suggest this will become a long term pattern.

With the Azores High showing it`s hand there`s every reason to look forward to some pleasantly warm and sunny days as we enter the first week of Summer.

[johnholmes]

I've ticked it as 'I like' but I feel I must support one of the regular objective posters that post into this thread. Thanks Phil for an as usual sensible level headed look at what the models are ACTUALLY showing in the time scale you mention.

[Alex]

I think there is too much pessimism wrt the model output by a few posters.

Indeed we are going to cool down during the rest of the week with onset of a cooler North Easterly flow and with some cloud and showers.

However because we have some heights over Greenland now it doesn`t mean they are going to adversly affect our weather for the foreseeable as one or two posts are hinting at.

The medium term outputs suggest retrogression of Greenland heights further to the West and a reallignment of the Scandi. troughing to sit more West to East to our North as we enter week 2.

Here the 8-14 day 500hPa chart and GFS/ECM Op. around days 7-8.

All suggest a more normal reversion to a warmer South Westerly flow as we get into next week.

As a general overview- yes we are approaching a less warm and settled few days, with showers around but there`s nothing to suggest this will become a long term pattern.

With the Azores High showing it`s hand there`s every reason to look forward to some pleasantly warm and sunny days as we enter the first week of Summer.

Yes, this is all very much in line with the evolution I pointed out yesterday evening, with the MJO looking to swing into phases 5/6 and with strengthing angular momentum, I would expect the Azores high to be a player with some ridging expected at times so probably changeable ESP in the north but drier further south with some decent days on offer.

Edited May 29, 2012 by Alex

[phil nw.]

Yes, this is all very much in line with the evolution I pointed out yesterday evening, with the MJO looking to swing into phases 5/6 and with strengthing angular momentum, I would expect the Azores high to be a player with some ridging expected at times so probably changeable ESP in the north but drier further south with some decent days on offer.

I don`t know how much we can consider any MJO influence at the moment Alex.It`s not been very strong for sometime-very close to it`s centre on the chart.

We do have a low amplitude 500hPa wave pattern around the hemisphere now which makes it difficult for models to place those the height anomilies with any consistency in the medium term.

We can see a very flat hemispheric flow at T144hrs with hints of a retrogressive pattern as i suggested earlier-those Northern heights becoming less of an influence with time to be replaced by low pressure to our immediate north.A more conventional UK Summer pattern.

I see the 12z GFS brings that low pressure further south towards the UK by later next week-keeping the Azores high at bay,different to earlier runs.

This highlights the model difficulties i was alluding too.

[The Northern Ramper]

Yes, this is all very much in line with the evolution I pointed out yesterday evening, with the MJO looking to swing into phases 5/6 and with strengthing angular momentum, I would expect the Azores high to be a player with some ridging expected at times so probably changeable ESP in the north but drier further south with some decent days on offer.

Interested to hear your thoughts on how Phase 5/6 will play out and what time scale this will begin/last for.

I don't know a great deal about mjo.

[Robbie Garrett]

I don`t know how much we can consider any MJO influence at the moment Alex.It`s not been very strong for sometime-very close to it`s centre on the chart.

We do have a low amplitude 500hPa wave pattern around the hemisphere now which makes it difficult for models to place those the height anomilies with any consistency in the medium term.

We can see a very flat hemispheric flow at T144hrs with hints of a retrogressive pattern as i suggested earlier-those Northern heights becoming less of an influence with time to be replaced by low pressure to our immediate north.A more conventional UK Summer pattern.

I see the 12z GFS brings that low pressure further south towards the UK by later next week-keeping the Azores high at bay,different to earlier runs.

This highlights the model difficulties i was alluding too.

I take it this is the answer to the long-range models showing the greenland block being replaced by low pressure?

[Thundery wintry showers]

From what I can see, the Bank Holiday weekend looks set to be cool, quite showery but also reasonably bright, especially towards the south-west where there probably won't be many showers around due to the low pressure being centred towards the E and NE- the direct arctic maritime airmass source and lack of mixing with continental air from the NE should help to prevent widespread overcast conditions. The isobars are quite well spaced, suggesting that it won't be particularly windy. After a cool end to the week with maxima of 12-15C likely on Friday for many of us, daytime temperatures will most likely rise to near normal by Monday, with highs of 15-18C, although nights will remain chilly.

There appears to be strong agreement on the prevailing airflow switching around to the west or south-west during next week and a weak ridge of high pressure over the south, allowing a couple of warmer days on Tuesday/Wednesday with a scattering of showers in the north and some sunshine. After that we'll be exposed to Atlantic depressions, and it's unclear how things will turn out from there. I can see parallels with recent summers in the GFS/ECMWF FI charts but note that recent summers had a strong jet powering across the British Isles- if we end up with a relatively weak jet then there's more chance of the low pressure spells being predominantly showery rather than dull and wet, and of the Azores high periodically throwing ridges up into Europe promoting more of an anticyclonic/southerly influence over the British Isles.