Model Output Discussion 18Z 18/6/13 onwards

[Downpour]

you mean this week or next week ?

He means next week – 27-28 June. 

Edited June 20, 2013 by Downpour

[Gordon Webb]

thanks , thought that's what you meant

[Summer Sun]

Longer range from the met office is suggesting a north south split now

 

Across northern areas, it is likely to be on the unsettled side with outbreaks of rain or showers at times, but also some drier and brighter interludes too. Conversely, the south will have some spells of fine and drier weather in between occasional rain or showers

 

Hopefully this will mean the jet stream is going to be further north than previous summers allowing pressure to rise especially but not exclusively for the south (depending on what there interpretation of south is of course)

[Frosty.]

 none of the currently available modelling suggest the likeihood of anything severe across the UK, let alone apocalyptic. 

in your opinion, I heard a few bbc forecasts which mentioned heavy torrential thunderstorms and flash floods, let's wait and see what transpires shall we, yellow warnings to turn amber soon...

Edited June 20, 2013 by Frosty039

[Captain Shortwave]

in your opinion, I heard a few bbc forecasts which mentioned heavy torrential thunderstorms and flash floods, let's wait and see what transpires shall we, yellow warnings to turn amber soon...

Trust us down here, no torrential rain, no thunder. Just grey skies and light rain. Radar shows that the rain in North West Scotland is more intense than the stuff down here 

[Frosty.]

Trust us down here, no torrential rain, no thunder. Just grey skies and light rain. Radar shows that the rain in North West Scotland is more intense than the stuff down here 

The worst weather is expected later today, tonight and tomorrow morning, especially for the southeast and eastern england.

Edited June 20, 2013 by Frosty039

[Thundery wintry showers]

Although 40mm might be overdoing it, there is some pretty serious rainfall likely to affect East Anglia in particular as we go through early tomorrow.  The storm rissk charts imply that the embedded thunderstorms will probably have largely fizzled out by the time they reach the British mainland, so just rain expected for most affected areas:

http://cdn.nwstatic.co.uk/gfsimages/gfs.20130620/06/27/ukprec.png

The weekend will have rain clearing eastwards early on Saturday leaving us in a sunshine-and-showers setup for the rest of Saturday and into Sunday.  However I think it will be the typically tame "British" version of sunshine and showers rather than the continental-style "sunny spells and sharp thundery downpours" type, with a fair amount of medium-level cloud associated with remnants of fronts tied in with the low, and shallow convection producing light to moderate showers.  The FAX charts highlight one such wrap-around frontal feature:

http://www.wetterzentrale.de/pics/brack2a.gif

 

There is now strong model agreement that a ridge of high pressure will extend over a significant portion of the country around midweek, which will promote dry sunny weather in central and western parts of the country with temperatures climbing up into the low 20s by day, but it is uncertain whether the warm sunshine will make it widely into eastern areas for more than 24-36 hours.  The GFS 06Z run strongly suggests yes, but the UKMO and ECMWF don't have quite as strong a ridge of high pressure.

 

The back end of next week is a long way off but the current model outputs are suggesting to me that the west-east split may reverse during the last couple of days of June, with a moist tropical maritime flow bringing grey and drizzly weather to the west, but chances of some warm sunshine at times to the east of high ground.

Edited June 20, 2013 by Thundery wintry showers

[Frosty.]

Not just east anglia, I go by the bbc forecasts and met office warnings and they say thunderstorms across some parts of southern and eastern england & wales today, but tonight and into tomorrow the storms risk transferring to the east of england with storms rumbling through the night and at first tomorrow before humidity levels drop as brighter, drier and fresher weather spreads across from the west during friday before wet and windy weather follows tomorrow night into saturday am and then sunshine and showers until early next week.

Edited June 20, 2013 by Frosty039

[Gordon Webb]

The Current BBC forecast do have the showers/storms worse by this evening in the midlands/East Anglia/SE England unfortunately for me but I've seen them before forecast and forecast and forecast and then 2 or 3 hours later change their forecast quite significantly

 

I'll just wait and see

Edited June 20, 2013 by Gordon Webb

[Methuselah]

We can only hope that there's a convergence zone somewhere way above the murk...

[Frosty.]

We can only hope that there's a convergence zone somewhere way above the murk...

Absolutely, and in the meantime, the netweather radar is going to be compulsive viewing as those storms burst into life and tracking the imported storms from france which will probably be more severe than our homegrown storms.

[Gordon Webb]

I'll also be watching the netweather radar but for completely different reasons

[AWD]

My thoughts on the next 10 days or so are that it's looking rather dry, especially so the further south you are and aside from the upcoming weekend, a lot of useable outdoor weather is to be had.

A look ahead then. Firstly, I'm not convinced about all this much hyped storm activity, this coming from a storm fan. There is potential for isolated thundery downpours around the South East and East Midlands area later, but even here the chance is relatively low IMO. Elsewhere, your either looking at cloud, drizzle, rain or hazy sunshine. More, and much better analysis of this however can be found in the convective thread.

Moving on to tomorrow then and for many of us it's looking like a mostly dry day with just a scattering of showers for some;

Plenty of weak, nuisance fronts around the country;

Giving a large amount of cloudcover however;

These fronts also sparking off a few, well scattered showers. Many of us should stay dry however, with temperatures up to around the seasonal average;

Although not as humid as recent days, there will still be a "muggy" feel to the weather over England and Wales with relatively high DP's;

And thickness values;

On Saturday, many of us should see some form of rainfall. Over the southern half of the UK this looks to be nothing more than drizzle or patchy light rain, over northern parts this will be a bit heavier, with some moderate falls;

With a load of grey crud, bits and pieces of nuisance, drizzly rain and below average temperatures for many;

Saturday is looking like a DANK day. You can see the front/depression responsible for the fresher, Atlantic dominated conditons below;

Later in the day, after the leading front has passed through, some convective activity might break out, thus something to watch for convective fans. After all, it can't be no worse than recent hope and failure.

Worth noting the strength of the isobars too, suggestive of some unseasonably strong winds over the weekend;

This could have an adverse affect on some outdoor activities such as the Weston airshow which I was hoping to attend.

On Sunday, we are still under low pressure domination;

But rather than frontal rainfall, the rain that does fall from the sky should be in the form of showers. No good posting charts showing the shower distribution this far out because it will change, as the nature of showers does. The isobars remaining tight so another windy day is likely;

Temperatures again disappointing for the time of year, especially giving this is the "longest weekend" in terms of light;

Looking at the total rainfall accumulations from the GFS by Sunday evening show nothing too substantial at all for the southern half of the UK, a little more perhaps for the northern half but even here, hardly worrying amounts;

Into the new working week then, do we see a change in our weather? Not initially no, but a little patience and as the week goes on, things look like improving substantially.

Monday looks like a tale of two halfs. In the east you are left with the weekend DANK;

In the west things should improve and become much drier, if not remaining rather cloudy still. This is all thanks to the trough dragging it's heels in clearing the east of the UK. Temperatures on Monday again, rather disappointing for the time of year;

The dissappointing temperatures are thanks to cooler uppers being dragged down from the north/north west;

With a lot of cloudcover around too, the sun is inhibited in helping minimise the effect of the below average 850hpa temperatures.

That's as far as we can look currently in the specific detail shown above. A look now at the rest of the working week in a more broad analysis. Firstly temperatures. These look like remaining a little below average or perhaps in the south, around average for the most part of the working week, with the exception of maybe Friday. This is due to a continual feed of below average 850hpa temperatures;

Now whilst locally, you may get something more seasonal IYBY, due to local environment conditons etc, taking the country as a whole, I think the high teens is going to be a typical thermometer reading for many of us for the first half of next week. Also worth pointing out the night time minima for the period in question too, something gardeners may want to pay particular attention to;

Whilst many urban areas may stay in upper single figures or low double figures, some rural western areas could stray very close to low single figures and ground frost conditons, dependant on cloudcover of course. Something to watch for now.

As for PPN, well as we progress through the working week things should become gradually drier everywhere for a time;

Might be the odd shower in the east, closest to the troughing, but really it will be a rather dry first half to the week. It will be a case of chasing cloudcover and sunshine I think, both will be prevalent on a regional bases but too early to say the extent of either currently.

How long will the dry and relatively settled spell last? Too early to say currently, dispite some enthusiastic Operational output. If we take a look at the UKMO and ECM at 144 hours (midweek next week);

We can see that they are both fairly similiar with troughing to our east (circled) and a strong ridge of high pressure coming up from the SW. This shows the small shower threat in the east well. It also shows the airflow to be generally north of west, hence the subdued temperatures. A look at the GFS at 144 hours;

and it's slightly different with shallower troughing to our east, thus allowing the ridge to develop a little further over the UK. What all 3 do show is a weakening of the Jet Stream north. As we go into the end of the working week and into next weekend things start to become a little more messy. The Met Office mention things becoming less settled from the north west and you can see this in the latest GFS Op;

The EC Det shows things turning more changeable to the north too, in association with a trough over the GIN corridor, but it shows much more of a struggle to push the changeable conditons any further south;

Until well into next weekend with the Jet Stream reluctant to push any further south than Scotland;

This is the Operational output however, and at this timescale is subject to vast change, as we have seen with the last two EC Det runs. Lets have a look at the ensemble data instead. The GEFS SLP suite shows the pressure rise clearly next week, but it does also show this to be a brief affair before values turn back towards average for the time of year;

These are for London. We don't see any true "low pressure" dominance there but what we do see is a more benign pattern setting up, similiar to the latest Met Office update of lengthy drier spells interspersed by occasional falls of light rain and showers. You can see that in the small increase in PPN spikes that I've circled.

The EC mean output for 192 hours;

And at 240 hours;

Show a flattening out of the pattern after the midweek ridge. Still with plenty of dry, useable weather in the south with occasional rainfall, a little more changeable for the north. A look at the NAEFS anomaly also backs up the above pattern for next week quite well. At 144 hours;

We have the troughing to the east and high pressure to the west. By 192 hours;

We have a decent ridge of pressure over the majority of the UK, giving a settled and dry midweek period. However, watch that trough to our north west. By 240 hours;

Weak troughing returns to the north of the UK as our ridge of pressure gets pushed back towards the Atlantic. FWIW, we are still under weak troughing come runs end;

Like I said before, the ridge of pressure next week is primarily thanks to a weakening Jet Stream pushing a little further north;

Even so, still very little rainfall shown to affect the southern half of the UK next weekend at this stage, good news for Glastonbury and Wimbledon. The GFS 192 hour rainfall accumulations show this well;

Little additional rainfall shown to the one I posted earlier in this post. A look at the 500mb anomaly charts show broad agreement between the main two;

along with the NOAA version;

All showing heights close by to our west/south west for the most part of next week, also showing the airflow to be north of west, again agreeing in the subdued temperatures likely. This may change to south of west as some FI NWP operational output shows if indeed the high does sink back SW next weekend.

And finally a look at the EC ens to see if they agree with any of the above. Temperature wise they do, with a largely average to slightly below average outlook for Birmingham;

And London;

Slight tentitive hints of something a little warmer than average beyond next weekend there, also supporters by some FI GEFS members;

So again, something to watch for now in the long run. Rainfall for London;

Show things flattening out somewhat after this weekends nuisance totals here, before various wetter options appear in FI. Similiar story for Birmingham too. The CFS v2 PPN projections also show average to below average rainfall for the next week at least;

So to summarise;

- a pretty DANK and fresh weekend coming up for all. Nuisance drizzly rain for the south, more moderate rainfall for the north. Temperatures primarily below average.

- into next week and a ridge of high pressure exerts it's influence from the South West. Whilst it may start showery in the east, things should slowly dry up and a dry midweek period for all looks favourable. Temperatures again no better than average however due to a below average 850hpa airmass and unknown levels of sunshine due to likely cloudcover for some of us. Some rather chilly night time temperature also possible for rural areas.

- towards the end of next week things look a little messy. A trough in the GIN area will exert pressure on our ridge from the north. This will squeeze our ridge promoting more changeable conditons towards the north. Unclear how far south these changeable conditons will get but I currently favour a good deal of useable, dry weather for the south still with just occasional rainfall. Temperatures perhaps creeping up towards average values.

Edited June 20, 2013 by AWD

[Methuselah]

Absolutely, and in the meantime, the netweather radar is going to be compulsive viewing as those storms burst into life and tracking the imported storms from france which will probably be more severe than our homegrown storms.

I'll believe it when I see it, Frosty...

[Frosty.]

I'll also be watching the netweather radar but for completely different reasons

I like storms, it's the most thrilling summer weather you can get.

[Frosty.]

I'll believe it when I see it, Frosty...

Yes, it's more about the potential right now than what's occuring, we will soon find out.

Edited June 20, 2013 by Frosty039

[J10]

As for the weather towards the end of June, It wouldn't surprise me that closer to the time winds revert back to more a Westerly / North Westerly which has been the theme for a while.

[shedhead]

I'll believe it when I see it, Frosty...

Ditto, I think what Frosty needs to accept is the MO will always err (quite rightly so) on the side of caution, both with regard to intensity and distribution of storm activity.  I tend to view the warnings they issue as being likely worst case senario 9 times out of 10, with today's output from them looking a classic case in point, but that is not to say some places will not get a deluge.  It's worth remembering this started after Frosty suggested the forecast was, at least for some areas 'apocalyptic' I saw nothing in the modelling to support that and I still don't.... neither by the way do I see anything within the current MO Warnings to support it either.

Edited June 20, 2013 by shedhead

[Frosty.]

As for the weather towards the end of June, It wouldn't surprise me that closer to the time winds revert back to more a Westerly / North Westerly which has been the theme for a while.

That's what the Ecm 00z ensemble mean shows and i'm sure the 500mb anomaly charts do too.

[Gordon Webb]

I like storms, it's the most thrilling summer weather you can get.

 

everybody to their own

 

Dull and Placid suits me fine

[Frosty.]

 

 

Dull and Placid suits me fine

sunny and placid suits me better,

[Tony27]

Well how often do we get a high risk of torrential thunderstorms over a wide area with warnings for torrential rain, i'm sure if you got caught in a torrential hailstorm or flash flood today, you would think differently, there is a high risk of disruptive weather today and tonight with hail, torrential rain and lightening strikes, probably not a plague of frogs or locust though.

well nothing here frosty, no sun, no rain and no thunder, its just been warm grey here this week instead of cold grey, you are like the press always over hyping things

 

However i have been keeping my eye on some rain for Friday which the GFS has been showing on and off all week flirting with the east coast, i will probably be too far south though and miss out http://cdn.nwstatic.co.uk/gfsimages/gfs.20130620/06/27/ukprec.png

[Methuselah]

Well how often do we get a high risk of torrential thunderstorms over a wide area with warnings for torrential rain, torrential rain and lightening strikes [?]

 

About ten times more often than they ever happen...And I think it's getting worse, too?

[Kentspur]

So am I right in thinking my holiday caravaning it in South Devon should be pleasant 24th/25th-29th June, then when I return home it will be better back in the South East than the south west? Keep seeing different posts saying different areas are inline to be the wettest/ driest etc

[Gordon Webb]

according to how the models are currently been described as far as I know YES I THINK