Model Output Discussion 12z 01/06/13

[phil nw.]

Here we are then a brand new thread on the first day of the meteorological Summer.

 

It looks like there will be some nice sunshine to start the new season for many of us in the next few days with a lot of dry weather about and daytime temperatures on the up after a cool(in the shade)weekend.

The 12z outputs are out next where we can see if a gradual change to less settled conditions is still on the cards later next week.

 

As ever please keep on topic and polite and put any general chat into the correct threads.

 

OK then continue below when you are ready.

[snowking]

That met office forecast has basically put every possible outcome 'there will be rain at times', 'it will be dry at times'.Anyway back in November 2012 I remember all the long term signals pointing to a easterly in December, it basically never came off. So regardless of what says what, nothing is ever certain. This time next week a lot will change, and I'm pretty sure the NAEFS and whatever else will be saying something different. No disrespect Snowking but how you can say what will happen in mid July, 6 weeks away I do not know, never mind October!

 

(Sorry to be a little off topic with the first post Phil - just a few answers to some of the queries from the previous thread!)

 

Hi Barry,

 

No offence taken, this is a discussion forum and this is what it's all about.

 

I think Tamara covered it pretty well above really. The only addition to make is that signal for the upcoming settled spell was there all the way back in late March when I first began compiling the preliminary summer forecast for another website, and indeed this was mentioned within that forecast too. So for me, this upcoming spell is the first major piece of verification for the forecast, aside from the overall cooler and unsettled theme projected for May. This is beginning to suggest to me that the analogue QBO and ENSO years selected are currently providing us with helpful hints towards the broad-scale (longwave) setup well in advance, and hopefully this helps to answer why I am now offering (with slightly more confidence) insights into the other strong signals derived from the forecast.

 

The next such strong signal for a decent settled spell (i.e. more than 2-3 days in duration) is during mid July.

 

The insight into the potential for a decent October, again as Tamara alludes to, should of course be taken with a pinch of salt being so far away. The technique I have used will have to be re-visited in a couple of months time to see whether my projections for the QBO and ENSO indexes are still following the same pattern as this summer - if they are, then the projection for October will have higher confidence. If not, then I will need to re-visit the analogue years to produce new composites for the autumn.

 

I completely understand, given the track record of previous such forecasts from various organisations, that there is, and will likely remain, a lot of skepticism surrounding LRF's - i'm in the same boat, I was sceptical even of my own forecast, and remain so until I see further verification. However, hopefully the initial hit with the upcoming settled spell helps to add a little confidence to the forecast. And if I end up being incorrect, well then let's all hope its for the right reasons - i.e. unbroken sunshine all summer long!

 

Also, just to answer 049balt's question quickly - i'm not expecting anywhere near the rainfall totals seen last year in the UK, with values likely to finish around the seasonal average. By way of comparison, here is the rainfall anomaly from last summer:

 

 

And here is the projection for this summer based upon the composite years:

 

 

Anyway, I had best get back on topic before I get myself in trouble!

 

Just as a quick update - the 0z Glasgow ensembles, rather similar to yesterdays 12z in terms of the increasing precip. signal beyond the 10th:

 

 

So unfortunately the medium range signal continues to be a less settled and slightly cooler one once again, much in line with the most recent ECM32 run with a cooler outlook beyond the first 10 days of June:

 

 

SK

 

Edited June 1, 2013 by snowking

[phil nw.]

No problem with your post in here SK but maybe it would be a good idea to put your longer range analysis type contributions in the slower moving in depth Model thread  -or at least a copy of them-here

http://forum.netweather.tv/topic/76236-in-depth-model-discussion-and-summaries/

 

Your excellent work and projections are always welcome but as you probably know by now their impact can be lost in this thread as the page total mounts-especially in busier times.

Carry on with the good work anyway,it's always good to read about the background indicators and views on where they may lead.

Edited June 1, 2013 by phil nw.

[Frosty.]

The latest Gefs 06z mean shows the high point of the anticyclonic spell being early next week and then a slow decline although most of next week looks like being warm and settled for many areas with long sunny spells for a while and temperatures inland widely into the high 60's/low 70's F and heading towards the mid to upper 70's across southern & southeast england later next week (cooler for counties bordering the north sea with a risk of occasional sea mist) as time goes on, the main anticyclone drifts away to the north of the uk and low pressure creeps towards the southwest. As next week goes on, there will be an increasing risk of scattered heavy showers with thunder but whilst some areas get a deluge, others could remain fine, warm and sunny, the driest conditions look like ending up further and further north as scotland holds on to higher pressure for longest but pressure continuing to leak away further south where it will also become more humid with the prospect of thundery rain and showers continuing to increase, eventually the mean shows unsettled weather spreading to all parts of the uk and after the warmth/humidity peaks next weekend, temperatures also begin to drop back slowly although probably remaining at least just above average to pleasantly warm, towards the end of the 6z mean, low pressure is further north in the atlantic heading towards nw scotland and high pressure is to the south of the uk so a northwest/southeast split takes shape with the sunniest and warmest weather across the south/se and northern & western areas (northwest britain) being more generally unsettled, cooler and windier with rain and showers.

[J10]

An excellent analysis there by snowking, however even in May, at least locally there were long periods of mostly decent weather including 16th-26th May and there a similar period of the start of May. So within a "unsettled" theme  of weather there will be period of decent weather, as such there is no need to get that despondent given what some long term tools are suggesting.

 

Even the MJO tools are not in complete agreement, some are suggesting 3 or 6, best not to go there, although it could be argued there is nothing new about this. Also CFS has been consistent suggesting an above average June, in terms of pressure, temps and below average rainfall for most. 

 

 

Clearly there is a trend for less settled conditions going forward, interesting though to see if this is a temporary pattern or a more sustained one.

 

In anycase, It could be much worse though, June 2012 anyone. I think most though would gladly take the average rainfall suggest by Snowking.

Edited June 1, 2013 by Jackone

[Thundery wintry showers]

The general theme that I'm seeing for the upcoming week is a west-east split with the western two-thirds of Britain warm, dry and sunny bar the odd isolated thundery shower, and the eastern third often cool and cloudy- the east to north-easterly flow has been toned up a bit on today's runs, suggesting that cloud may penetrate a fair way inland at times.  For example, take the GFS 06Z's projected maxima for 1500 on Wednesday:

http://cdn.nwstatic.co.uk/gfsimages/gfs.20130601/06/105/ukmaxtemp.png

Allowing for the traditional underestimation from the GFS, most of the western two-thirds of Britain should be up at 18-21C, with 22 or 23C in some sheltered western spots (notably central and western Ireland) but near the east coast maxima of 13-15C are suggested.  Overall, much as per early June 2007 but a cooler version because of the lower SSTs in the North Sea.  It should still be warm enough for a positive start to the summer for outdoor activities in most central and western areas though.

[Summer Sun]

Looking at the 12z GFS this afternoon and the new working week will start off with some decent sunny periods for many

 

 

Into Tuesday and we see some thick cloud plaguing the south whilst else where its thinner allowing the sun to break through

 

 

Into Wednesday the east coast is stuck with the cloud during the morning but this is shown to thin and burn away during the afternoon for all but the South east and NW Scotland

 

Edited June 1, 2013 by Gavin.

[Barry12]

Differences between the UKMO and GFS at just 96 hours, UKMO looks much better especially for the south

the low hits Scotland on the GFS whereas it stays east of Scotland on the UKMO. Also the UKMO doesn't have low pressure effecting the south as of yet with the south keeping the high pressure for longer.

 

 

 

 

GFS keeps the high pressure for all at 120, the low to the SW is much nearer the UK on the UKMO.

 

 

GFS at 144 is an improvement to previous runs with more settled conditions, UKMO at the same time seems better for more settled conditions, but if that low to the south moves further north there could be heavy thundery downpours.

 

 

 

GFS at 168 and 192 show conditions deteriorating for the following weekend, with unsettled conditions arriving. Especially by Sunday as the low to the south moves North and effects the UK.

 

 

 

Long term GFS is much better, low pressure stays firmly over Greenland with high pressure starting to push into the UK again in 12 days time. Hopefully this is a trend for the long term. The scary yellow colours don't attack Greenland on this run!!

 

Edited June 1, 2013 by Barry95

[Summer Sun]

Not a bad outlook at all tonight settled for the next 5 days or so before a breakdown but its only short lived before we see another building of pressure

[J10]

Looking at tonight's runs  - the general theme of High Pressure gradually edging Northwards and pressure lowering in the south is continue, with showers becoming increasingly possible toward the weekend. No surprises there for anyone.

 

According to GFS 12Hz, Low Pressure pushing in from Sunday from the south, but the current GFS keeping the worst of the conditions into the continent until the Monday. but quite a wet few days

 

Synoptics

 

http://cdn.nwstatic.co.uk/gfsimages/gfs.20130601/12/174/h500slp.png

 

http://cdn.nwstatic.co.uk/gfsimages/gfs.20130601/12/192/h500slp.png

 

http://cdn.nwstatic.co.uk/gfsimages/gfs.20130601/12/216/h500slp.png

 

http://cdn.nwstatic.co.uk/gfsimages/gfs.20130601/12/240/h500slp.png

 

http://cdn.nwstatic.co.uk/gfsimages/gfs.20130601/12/264/h500slp.png

 

Rainfall

 

http://cdn.nwstatic.co.uk/gfsimages/gfs.20130601/12/174/ukprec.png (Showery Saturday)

 

http://cdn.nwstatic.co.uk/gfsimages/gfs.20130601/12/192/ukprec.png (Rain starting to edge in)

 

http://cdn.nwstatic.co.uk/gfsimages/gfs.20130601/12/216/ukprec.png (Rain over S/SE - low res)

 

http://cdn.nwstatic.co.uk/gfsimages/gfs.20130601/12/240/ukprec.png (Rain over S/SE - low res)

 

We can see High Pressure starting to re exert its influence from the West towards the middle part of the following week, only 1 run,  but interesting to see what happens after next weekend.

Edited June 1, 2013 by Jackone

[Frosty.]

Considering how the models are generally showing a slow decline in conditions from the south towards the end of next week, this evening's ukmo 12z is a very nice surprise with a strong looking anticyclone still well in control of our weather, hopefully high pressure will have longer lasting influence in the next 7-10 days rather than the anticipated northward migration of the high with falling pressure to the south, let's enjoy the warmer settled conditions for however long it lasts.

[Summer Sun]

Considering how the models are generally showing a slow decline in conditions from the south towards the end of next week, this evening's ukmo 12z is a very nice surprise with a strong looking anticyclone still well in control of our weather, hopefully high pressure will have longer lasting influence in the next 7-10 days rather than the anticipated northward migration of the high with falling pressure to the south, let's enjoy the warmer settled conditions for however long it lasts.

 

Yes I was pleasantly surprised by tonight's UKMO longer term looking at that the high has a while to go yet before any major breakdown occurs

 

Edited June 1, 2013 by Gavin.

[reef]

Considering how the models are generally showing a slow decline in conditions from the south towards the end of next week, this evening's ukmo 12z is a very nice surprise with a strong looking anticyclone still well in control of our weather, hopefully high pressure will have longer lasting influence in the next 7-10 days rather than the anticipated northward migration of the high with falling pressure to the south, let's enjoy the warmer settled conditions for however long it lasts.

 

A setup like that shown by the UKMO is absolutely no guarantee of good weather on the ground (as TWS mentions above). I wouldnt be suprised if the weather in quite a few areas was pretty poor with that chart, with the still rather cold North Sea generating lots of cloud which could be particularly stubborn. Potentially the Midlands and central areas could be affected too.

 

Its seems to be a common theme in this thread at the moment by some to see high pressure somewhere near the UK and assume the weather will be warm and settled. Its commonly not the case. If anything I would argue that any real countrywide warm and sunny weather is very far away with the high pressure centred so far to the North. Ideally it needs to be positioned over the continent dragging in a SE or preferrably SSE flow.

[Evening thunder]

The chart the UKMO shows gives quite a high likelihood of good weather for the SW, W (i.e Wales), Ireland, NW, and much of Scotland at least though.

Quite a tasty chart for me in my normal location of east Devon, I can't remember similar charts at this time of year that haven't given some warm sunshine even if a couple may have had a bit of patchy cloud (perhaps from the North Sea) a minority of the time. Indeed due to the location of the English channel it is pretty much the best wind direction (at least at the surface) for warm temperatures at home. A low closer to the south shouldn't be a problem for my preferences as it could add some thundery interest.

 

Of course in the east particular and maybe even some central areas sometimes it may not be so appealing, so can understand those near the east coast not feeling too enthusiastic over the charts if they want warm sunny weather, although the winds are quite light in the northern half of the UK.

I would rather be at home for this spell than just west of London (even with similar weather it's better to be in Devon..) but don't think the weather will be too bad here with charts like the UKMO run. As often is the case it is a matter of location.

[pad199207]

So indeed a fine week of weather to be had next week!

[Thundery wintry showers]

I think the UKMO chart at T+144 probably would bring warm dry sunny weather to most of the country with low cloud largely confined to east-coast counties, as the high pressure is strong and the easterly flow is quite weak.  Tonight's GFS on the other hand could well bring cloud and suppressed temperatures a fair way inland over eastern England during mid to late week which could penetrate into the Midlands at times:

http://cdn.nwstatic.co.uk/gfsimages/gfs.20130601/12/144/h500slp.png

http://cdn.nwstatic.co.uk/gfsimages/gfs.20130601/12/147/ukmaxtemp.png

 

It will be interesting to see which way the ECMWF goes- this morning's ECM run had a fairly stiff east to north-easterly flow which was more in line with this evening's GFS.

So indeed a fine week of weather to be had next week!

For Ireland I think that assessment is looking almost nailed on, bar some well-scattered thundery downpours around midweek.  It's rare for Ireland to have the warmest and sunniest weather in the UK but it could well happen this week.

[J10]

A setup like that shown by the UKMO is absolutely no guarantee of good weather on the ground (as TWS mentions above). I wouldnt be suprised if the weather in quite a few areas was pretty poor with that chart, with the still rather cold North Sea generating lots of cloud which could be particularly stubborn. Potentially the Midlands and central areas could be affected too.

 

Its seems to be a common theme in this thread at the moment by some to see high pressure somewhere near the UK and assume the weather will be warm and settled. Its commonly not the case. If anything I would argue that any real countrywide warm and sunny weather is very far away with the high pressure centred so far to the North. Ideally it needs to be positioned over the continent dragging in a SE or preferrably SSE flow.

 

Depends what you mean by warm and settled, if you mean temps high teens/low 20s and dry bright weather then the next week will deliver, at least for most. Getting a heatwave is a another story, but I have not really seen that many posts saying that.

 

There are very few conditions that give wall to wall sunshine to the UK, a moist SW flow this time of year, would mean yucky weather for us, but possibly very warm weather for the E/NE. But for us down here a High Pressure with E/NE is pretty good, with good warm sunshine especially as upper temps are quite high to the North East at the moment.

 

In short it is better having High Pressure than a trough bang on top of us circa June 2013, however you are right that there is sometimes that High Pressure can be seen as a panacea,

[phil nw.]

Yes it's fair to say with the High migrating just to our north through the week then an east/n.easterly flow will have us chasing the cloud breaks especially further east.

In a weaker flow then the strong June sun would burn back a lot of the cloud to the coastal strip through the mornings-i have seen this happen quite a lot here in the Midlands over the years in this setup.

Indeed a weaker easterly can bring some of the most enjoyable conditions for outdoor activities -low humidity,brilliant sunshine and clear visibility-assuming the clearance of any cloud of course.

 

On another note this GFS run keeps the main area of rain just to our south by next week end-indeed the op shows quite a spike around day 10 for C.England,compared to the mean which only shows small amounts of pcpn from any unsettled incursion.

 

From this range i am sure we will see adjustments to any low pressure to our south or south west from  the models over the next few runs.

 

 

[Carlrg]

Looking at the models for the 10th June, not one is in agreement. All to play for in the medium term imo. The Gem 12z is just that a gem of a chart.

 

 

 

http://www.meteociel.fr/cartes_obs/comp_panel.php?mode=0&ech=216&size=2

Edited June 1, 2013 by Carlrg

[Frosty.]

A setup like that shown by the UKMO is absolutely no guarantee of good weather on the ground (as TWS mentions above). I wouldnt be suprised if the weather in quite a few areas was pretty poor with that chart, with the still rather cold North Sea generating lots of cloud which could be particularly stubborn. Potentially the Midlands and central areas could be affected too.

 

Its seems to be a common theme in this thread at the moment by some to see high pressure somewhere near the UK and assume the weather will be warm and settled. Its commonly not the case. If anything I would argue that any real countrywide warm and sunny weather is very far away with the high pressure centred so far to the North. Ideally it needs to be positioned over the continent dragging in a SE or preferrably SSE flow.

I only partly agree with you, the ukmo 12z chart at T+144 indicates light winds and high pressure in control, nobody knows for sure how persistent any cloud cover across eastern areas at T+144 hours would be, there might only be some transient low cloud or sea mist which could easily burn back to the coast or even well offshore and the sun is very high and strong in June so the jury is out as to whether it would be cool, dull and mizzle or be (or become) fine, pleasantly warm and sunny.

Edited June 1, 2013 by Frosty039

[Methuselah]

I only partly agree with you, the ukmo 12z chart at T+144 indicates light winds and high pressure in control, nobody knows for sure how persistent any cloud cover across eastern areas at T+144 hours would be, there might only be some transient low cloud or sea mist which could easily burn back to the coast or even well offshore and the sun is very high and strong in June so the jury is out as to whether it would be cool, dull and mizzle or be (or become) fine, pleasantly warm and sunny.

My guess: the warmer the uppers and the higher the RH, the thicker the North Sea cack...but, as you say: who knows?

Edited June 1, 2013 by A Boy Named Sue

[Summer Sun]

ECM is also showing pressure to try and re-establish its self in a weeks time

 

 

With temperatures around average

 

[Skeggy Winter Storm]

I only partly agree with you, the ukmo 12z chart at T+144 indicates light winds and high pressure in control, nobody knows for sure how persistent any cloud cover across eastern areas at T+144 hours would be, there might only be some transient low cloud or sea mist which could easily burn back to the coast or even well offshore and the sun is very high and strong in June so the jury is out as to whether it would be cool, dull and mizzle or be (or become) fine, pleasantly warm and sunny.

i agree Frosty ive seen plenty of times ive woken to grey skies here in the mornings but its burnt back as you say sun is strong and high up yesterday was an example was very cool at first turned out a lovely day

[Frosty.]

My guess: the warmer the uppers and the higher the RH, the thicker the North Sea cack...but, as you say: who knows?

My guess would be, dull misty am and sunny pm if I had to make a snap decision on it, kind of a compromise between dreek haar and sunny throughout.

[AWD]

IMO nothing much has changed over the last few days.

There have been variations of the pattern but the broad trend is for a settled and sunny working week for most of us with temperatures around average (give or take a few degrees depending on location).

As the week progresses and we come to the end of the working week and into the weekend we see a relaxation in SLP values, enough to promote shower activity in places, these showers possibly thundery.

This showery theme continuing through next weekend and into the start of the following week. Temperatures remaining around average.

I see no return to a deeply unsettled regime within the next 7-10 days and I see no heat wave or hot temperatures within the same timescale.

Typical June weather. Plenty of sun, some showers with time, respectable temperatures.

Edited June 1, 2013 by AWD