Model Output Discussion 14th May 2012 Onwards

[tinybill]

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

morning sorry the person to bring bad news looks like even into deep F1 us in the uk will have to put away the suntan lotion and find the wellies and macs looks like it could get a bit cool and and a lot of rain heading our way

[shedhead]

Even given the GFS' propensity to overcook expected minima, the kind of values we're likely to see later this week will be a real shock to the system and could be some 14-16c below

what we saw last Friday. Still plenty of dry weather around across the short to medium term however, but any half decent temps looks set to be confined to the far south and west, with

only the hardiest of hardy souls likely to fancy a dip in the N Sea during the long B H Weekend...

Edited May 28, 2012 by shedhead

[Alex]

Big drift of the MJO during last 2 days, now hints of phases 4/5. This will impact on FI heavily during the next few days and a pattern may not establish for a few days while we shift away from progged patterns of 8/1.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjo.shtml

[Costa Del Fal]

Big drift of the MJO during last 2 days, now hints of phases 4/5. This will impact on FI heavily during the next few days and a pattern may not establish for a few days while we shift away from progged patterns of 8/1.

http://www.cpc.ncep....k/MJO/mjo.shtml

What conditions can we expect from this? I presume Northern Blocking and cool for Britain however I dont know.

Meanwhile GFS 12z more positive next week with high pressure trying to build in again however its very different to recent runs so I have my doubts for now.

Edited May 28, 2012 by Blizzards

[William of Walworth]

please lets not make the mistake of over analysing op charts beyond day 7. wait for the ens. PE - 2 weeks ago' date=' you were a disciple of the daily express and look what happened. what is incredible is the persistence and strength of the retrogressive signal in our part of the hemisphere. i think that could well mean some pretty hot conditions as we move through the second half of june if the pattern holds.

[/quote']

No one forecast this hot spell correctly, not the MO or anyone here.

And certainly not you.

You're utterly incapable of predicting any benign/summery weather, anywhere, ever.

You're one of the least trustworthy model readers on this thread, because you trawl the models and somehow, amazingly, without fail, will find the most unsettled/coolest/wettest possible outcome out of various different possibilities.

Yet another case in point, merely the latest :

The chart preceding this hints strongly of the Upper trough moving SW towards

the UK in a weeks time - Its preferred position. If it sets up shop if it lasts as long as it did last time it will still be there come mid July.. What makes you thing we will have hot conditions from the middle of June ? Remember not to over analyse charts beyond 7 days, especially if they show a return to the average British summer.. This time next week the UK is surrounded by High Pressure to the SW, NW, NE and further SE.. with the only place for LP to go, over the UK..

Wow that is some drop in temps as we go into the beginning of June !

How unsurprising ....

ETA : Apologies for the offtopicness of that, which I now see Osbourne has warned people about. Couldn't help myself!

More ON TOPIC : my current expectation for the coming weekend on the latest output right now is similar to ledders above -- reasonably dry and pleasant for most places, but by no means hot or even all that warm.

But the constant health warning remains, lots of scope for changes in the detail/positioning as we move closer. As ledders also rightly said , very rash to try predicting much beyond the next 7 to 10 days. So summers writer-offers in particular please take note!

Edited May 28, 2012 by William of Walworth

[Alex]

What conditions can we expect from this? I presume Northern Blocking and cool for Britain however I dont know.

Meanwhile GFS 12z more positive next week with high pressure trying to build in again however its very different to recent runs so I have my doubts for now.

I would think that it's probably more suited to a trough to the north with ridging to the south ESP with the increasing angular momentum, something akin to the recent winter Synoptics. I would add though a more stronger MJO will need to drive this change.

FI is likely to change a bit for a few days whilst it adapts with little pattern direction as you note in the complete differences of the recent GFS runs!

[Summer Sun]

UKMO is also unsettled tonight

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

The ensembles will be interesting later to see how much support there is for GFS FI

[Summer Sun]

ECM is fairly unsettled tonight as well

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

[Frank Trough]

ECM is fairly unsettled tonight as well

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

it isn't just "unsettled" or "settled". There are a plethora of solutions in between - i.e. weather.

I quite like the trend from the GFS and ECM tonight (and it follows on the runs this morning). Cooler Jubilee weekend everywhere (it was always going to be, wasn't it?!) but i don't think it'll be a disaster in the south and west. Then the GFS and ECM both indicate the Atlantic low pushing warmer air up from the south from midweek (next week). Plenty of scope for change, obviously and inevitably there will be.

[PubliusEnigma]

Something of better prospect for the B/H weekend on both the 12Z ECM & GFS. Coolest weather reserved for the North east and the

best of any brighter weather now in the SW and Southern Ireland. A similar pattern Sun thru Tues with Slack winds North or N Easterlies.

should mean Bright sunny dawns after following cold nights with cumulus building up and flattening out to shut out the sunshine until supper

time when the clouds thins and melts away at sunset. I would suggest average or just below average temps for the time of year around

the ranging from 10 or 11oC in the East to 13oC or 14oC in central and southern parts..

You may do well not to plant out any tender bedding plants just yet.. GFS hits at -3oC in some central parts over the weekend.

Personally I think it won't get that low.. Maybe a 0oC or possibly a -1oC on Sandy loans in some well renowned frost hollows.

NOGAPS paints a winter paradise chart.. It would be bedlam in here, and snowing in many places if a chart cropped

up like that at the end of January with cold air sourced right from the north pole.. :o

[ANYWEATHER]

Both Ecm and Gfs showing a much cooler/unsetteld outlook from Friday ...

[Deluxe]

Something of better prospect for the B/H weekend on both the 12Z ECM & GFS. Coolest weather reserved for the North east and the

best of any brighter weather now in the SW and Southern Ireland. A similar pattern Sun thru Tues with Slack winds North or N Easterlies.

should mean Bright sunny dawns after following cold nights with cumulus building up and flattening out to shut out the sunshine until supper

time when the clouds thins and melts away at sunset. I would suggest average or just below average temps for the time of year around

the ranging from 10 or 11oC in the East to 13oC or 14oC in central and southern parts..

I would take those temperature charts with a hefty handful of salt! Also you're not suggesting those temperatures, you're reading off what the GFS says, which at this stage looks to be -3-4c off the mark. A max of 13-14c in central and southern areas is complete nonsense IMO. Before someone suggests it, yes I do enjoy the warmth, and I'm not in denial over the cooler spell coming up, however I'm not the only one on here who knows those maximums are too low - it's a GFS habit.

Edited May 28, 2012 by Hartle

[PubliusEnigma]

Both Ecm and Gfs showing a much cooler/unsetteld outlook from Friday ...

Is looking that way.. The BBC / MO long ranger have picked up on the trend in their monthly outlook to the

end of June. With the south coming off worse with below average temps at times.. Of course it could still change

but we would need to see a significant pattern change..

Monday 4 June—Sunday 10 June

The gradual return of some wet weather?

It will stay mainly dry and bright across many parts of the UK into the second half of the Jubilee weekend with the chance of some good spells of sunshine for western areas. There'll tend to be more cloud across southern and eastern areas where the cloud may thicken enough for the odd light shower. Temperatures will be around average for the time of year and accompanied by light winds but in the cloudier eastern areas, temperatures may be a little below average.

Moving into the early part of next week, there won't initially be a great deal of change with high pressure continuing to bring mainly dry and bright conditions to most areas. There will always with the threat of more cloud running down the North Sea though, threatening eastern parts with the odd shower.

By the end of the week conditions look more unsettled towards northwestern areas with the risk of rain and showers developing and spreading to all areas. At the moment there aren't any strong indications of another spell of very warm weather during this period but it should still feel pleasant in the brighter and drier interludes with temperatures reaching average values.

Monday 11 June—Sunday 24 June

No sign of a flaming June just yet

Early indications suggest that most areas of the UK will be affected by rather changeable weather through the middle part of June, with showery spells and periods of more prolonged rainfall. That said, there should also be some brighter periods too. At the moment it looks as if the south will bear the brunt of the more unsettled weather, with the drier and brighter weather being to the north. Forecast temperatures don't look particularly out of the ordinary with average values anticipated. That said, southern areas that do see more rain may well experience temperatures that are just a touch below the June average.

Both Ecm and Gfs showing a much cooler/unsetteld outlook from Friday ...

What do -5oC's uppers equate to roughly at ground level in terms of surface temps ??

[samadamsuk]

Hey all.

Big question to me is does the trough set up and continue to drain the ploar northerlies across us, or does the low out in the atlantic join in the fun and form a more SW/NE trough with us parked on the warm advection side of it as the polar outflow goes over the top and into the atlantic. If the latter is the case I think we'll be in for more hot and humid weather after the bank holiday - i not then we could see some big rain events in june imo!

Cheers, Sam

[William of Walworth]

I always used to follow the weekly updates to the BBC forecasts in summertime - are they still updated every Monday? Those are Met Office output based aren't they? One thing I remember from last summer is that because of the infrequency of the updating, they can fluctuate madly at times from update to update. And obviously become progressively less up-to-date/useful as the week goes on. Monday/Tuesday being the best time to catch them (unless I'm out of date -- feel free to correct me).

Edited May 28, 2012 by William of Walworth

[William of Walworth]

Sam's right -- it's all about the positioning of the trough isn't it?

I was also interested in what Robbie Garrett was posting a while back about Northern blocking, which he didn't necessarily foresee persisting throughout future weeks.

Personally I dream of a summer where the Jet becomes Northerly tracking (at least most of the time) with Lows going past us to our West and North, rather than crashing right into us so frequenrly, as in many recent, wetter summers. Northerly tracking was what was supposed in some years to be our traditional summer synoptic track, but the persistent Southerly track in some recent years made that idea a bit of mockery.

Any thoughts on Jet positioning this year, other posters? I appreciate the Atlantic doesn't seem all that active right now but if that changes, where the Lows head becomes all-important at this time of year.

Edited May 28, 2012 by William of Walworth

[johnholmes]

What do -5oC's uppers equate to roughly at ground level in terms of surface temps ??

see the pdf posted below which I hope helps?

[johnholmes]

the podf re 850mb temperatures and surface values

sorry it is a bit small so hope those interested are able to enlarge it?

Edited May 28, 2012 by johnholmes

[PubliusEnigma]

Sam's right -- it's all about the positioning of the trough isn't it?

I was also interested in what Robbie Garrett was posting a while back about Northern blocking, which he didn't necessarily foresee persisting throughout future weeks.

Personally I dream of a summer where the Jet becomes Northerly tracking (at least most of the time) with Lows going past us to our West and North, rather than crashing right into us so frequenrly, as in many recent, wetter summers. Northerly tracking was what was supposed in some years to be our traditional summer synoptic track, but the persistent Southerly track in some recent years made that idea a bit of mockery.

Any thoughts on Jet positioning this year, other posters? I appreciate the Atlantic doesn't seem all that active right now but if that changes, where the Lows head becomes all-important at this time of year.

Things definitely seem to be on the change. Take this weeks breakdown. Its arriving from the north east. What ever happened to three hot days and a thunderstorm. Cooler cloudy weather oozes south into northern England and Eastern parts with cloud and light and patchy rain showers, rather than a thundery Spanish Low moving north across western France and into southern England. You used to lay in bed at night in sweltering sultry conditions. Not even a breath of air outside. And then usually around 2AM.. the curtains would begin to flap wildly in the wind and wake you. A distance flash of lightning would illuminate the bedroom, but no thunder yet. The air already began to fell a little cooler and fresher in the gusty breeze. Then you would hear your first distant rumble. You would rush to the bedroom window and see lightning in one direction and then spot flashes in other directions.. You knew a thundery low was heading your way.. It would rain like stairods as the ground disappeared in a mist due to the intensity of the rain.. Alas.. northerly breakdowns as in this week see cooler air rolling south as increasing amounts of stratus spread in and the temp slowly falls.. and thats it.. I wonder if this year will be the year of the northerly breakdown where in recent summers the breakdown has come mainly from the west.

[PubliusEnigma]

the podf re 850mb temperatures and surface values

sorry it is a bit small so hope those interested are able to enlarge it?

Tanks John. So -5oC uppers equate to 10oC at ground level.. Surely the sun at this

time of year must modify those values if its not too windy ?

[Robbie Garrett]

Sam's right -- it's all about the positioning of the trough isn't it?

I was also interested in what Robbie Garrett was posting a while back about Northern blocking, which he didn't necessarily foresee persisting throughout future weeks.

Personally I dream of a summer where the Jet becomes Northerly tracking (at least most of the time) with Lows going past us to our West and North, rather than crashing right into us so frequenrly, as in many recent, wetter summers. Northerly tracking was what was supposed in some years to be our traditional summer synoptic track, but the persistent Southerly track in some recent years made that idea a bit of mockery.

Any thoughts on Jet positioning this year, other posters? I appreciate the Atlantic doesn't seem all that active right now but if that changes, where the Lows head becomes all-important at this time of year.

We are going from this....

to this...

Very wet start to June likely.

Azores high builds, end of June - we are back to where we are now....

Low pressure builds into below the high, stopping it from west of the Bay of Biscay (a likely solution)

Likely situation for me is high pressure firmly building into Europe, with low pressure firmly to the west of the Iberias/Portugal pumping that air up.

This is a long range model and as people have said use it with caution but it does say Northern Blocking may rid itself shortly...

[johnholmes]

The value is not something set in stone, merely a guide. With full sun I would suggest somewhere between 14 and 20C is probably the range to expect. BUT there is yet another factor to take into consideration-super adiabatic heating close to the surface. This occurs, usually in summer, when there is little wind, a very dry atmosphere, and a dry surface. This can add a further 2-6C in some instances.

So as you see, and all these things are already fed into the computer at start up time it is a very complex calculation.

My personal suggestion for the weekend and with -5C at 850mb would be, 9-12C, it is only the NE 1/3 of Scotland that GFS is predicting a -5C, other areas it is about zero C or a bit above.

I did remember some time later that I still have a copy of the Forecasters Handbook which is used as a written guide for new forecasters, updated as required. There are a number of other methods used which had slipped my mind at the time.

1000-850mb thickness, a whole host of MOS calculations (Model Ouput Statistics) for scores of places around the uk. These go back to the days long before computers when, in the dead of night, we often complied data for all manner of things to try and improve local forecasts. Min, Max, snow, etc etc and were then checked by the computers over several years before being accepted as part of the MOS data routinely fed into the models.

If I get chance I will copy 2 or 3 pages and add as a pdf at some stage. A bit under the weather at the moment though.

Edited May 29, 2012 by johnholmes

[PubliusEnigma]

The value is not something set in stone, merely a guide. With full sun I would suggest somewhere between 14 and 20C is probably the range to expect. BUT there is yet another factor to take into consideration-super adiabatic heating close to the surface. This occurs, usually in summer, when there is little wind, a very dry atmosphere, and a dry surface. This can add a further 2-6C in some instances.

So as you see, and all these things are already fed into the computer at start up time it is a very complex calculation.

My personal suggestion for the weekend and with -5C at 850mb would be, 9-12C, it is only the NE 1/3 of Scotland that GFS is predicting a -5C, other areas it is about zero C or a bit above.

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 ?

[johnholmes]

The pdf I promised looking at possible reasons why the heat was not predicted very far ahead?

Forecasts for the hot spell-28 may 2012.pdf

[Cheese Rice]

I would take those temperature charts with a hefty handful of salt! Also you're not suggesting those temperatures, you're reading off what the GFS says, which at this stage looks to be -3-4c off the mark. A max of 13-14c in central and southern areas is complete nonsense IMO. Before someone suggests it, yes I do enjoy the warmth, and I'm not in denial over the cooler spell coming up, however I'm not the only one on here who knows those maximums are too low - it's a GFS habit.

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.

Edited May 28, 2012 by Cheese Rice