Model Output Discussion 30/06/2012

[ANYWEATHER]

Hello Jonathan and welcome to the forum.

Yes at the moment next week looks drier at least as weak ridging extends from the Azores High.

so something a bit better for a few days perhaps.

But despite gfs output, Ecm makes nothing of the Azores High at this time range.......

[Luke McDonnell]

Bit of wishful thinking here, I was just wondering if there has been an instance where a pattern has changed in a stubborn pattern scenario and output has not picked up on it,Guessing it must be possible,In cases of hurricane activity or volcanic activity or something else.Would be interesting to know even better with detail.????

JT

I think that hurricane or tropical storm activity can cause changes at short notice in the synoptics - I do remember that the warm spell in July 2008 emerged at very short notice due to the effect of a hurricane coming of the eastern seaboard - does anyone remember how that evolved in the models? Yes people have came out to say that the pattern is set in for the foseeable and may last until the end of July but that is subject to unforseen changes at short notice - we do not know what the impact of the hurricane season will have on the synoptics in this part of the world.

[Thundery wintry showers]

This post is a good example of how you can end up chasing yer tail by trying to be too precise in this type of situation. What you said earlier this week has undoubtedly proven to be correct in so much as some places have seen little in the way of rain and even a little warm sunshine, but given the fact LP remains over or close to the UK for several more days the emphasis has to remain on showers or longer spells of rain imo, some of which will be heavy and thundery.

It's one of those areas where forecasting can be very tricky. I recall many examples of forecasts talking apologetically of dire unsettled weather only for the reality to be sunny with occasional sharp downpours leaving most people wondering what all the gloom was about, but in avoiding that trap I sometimes fall into the opposite one, i.e. forecasting brighter showery weather only for generally dull wet weather to persist. Even settled anticyclonic conditions catch us out sometimes, e.g. when slight changes in the positioning of the high make a large difference to cloud cover and consequently daytime temperatures.

This weekend is another forecaster's nightmare as the models are continually shifting the main belt of frontal rain. Friday is now looking like a complete washout except for the far south-east (sunshine and showers) and north-west (dry albeit rather cool and cloudy). Saturday, on the basis of the GFS 12Z, may see the rain belt retreat northwards to Scotland allowing England and Wales to become brighter and warmer with some showers, then on Sunday the rain belt looks set to head back south again in the northerly airstream though the rain associated with it will not be quite as heavy by this time.

The models seem to be all over the place regarding the specifics for next week, as I remember remarking earlier that they showed a repeat of June's weather, but the ridge from the Azores High on the GFS would indeed bring us a few mainly dry days with sunny intervals and just a broad scattering of showers, albeit remaining on the cool side. Meanwhile the UKMO/ECMWF keeps us in a north-westerly regime which would probably be cool with some belts of frontal rain interspersed with mainly cloudy conditions, a little sun and a few showers, but they have backed away from projecting deep southerly tracking lows.

[phil nw.]

But despite gfs output, Ecm makes nothing of the Azores High at this time range.......

Indeed Anyweather and by 168 it goes downhill !

UKMO/GFS at T144 do look less cyclonic than the 12z ECM Op and are similar to the 00z ECM mean in trying to bring in something less unsettled into next week.

Although this is all relative in relation to what we have at the moment we would still have some showers about in a coolish flow from the north so temperatures will still be rather on the low side for many as i have said.

Overall the main core of the Azores high remains too far away to our south west and It` is difficult to latch onto anything really Summery at present.

[damianslaw]

In a word the models continue to suggest a very changeable outlook for the foreseeable future. Short term and we have a potentially very troublesome 24 hours or so period ahead starting thursday evening and running into Saturday. Developments over the near continent in the form of a potent frontal feature is set to move NW across the country bringing further very heavy torrential rain. Just where will see the heaviest precipitation is difficult to say. GFS has northern england and SE scotland in the firing line, Meto also suggests these areas will be worse affected, not good news for NE England in particular given the flooding of last week.

Into the weekend and the frontal feature will slowly drift eastwards slowly along with the low pressure as we see heights rising to our west ushering in a cool long draw northerly for early next week which will mean cool conditions and further heavy showers but SW parts could see some decent dry weather.

None of the models are suggesting any signs of the azores high ridging NE anytime soon - look at its progged position far to the west , not good news at all, with the state of the northern hemisphere, the path for the trough to continue to trouble the country will therefore remain firmly clear.. what a shocking first half to summer 2012!

Off topic but have to say this -

If the last three months had been our winter - what a snow fest freeze fest we would have endured.. the synoptics being ideal for sustained cold and copious amounts of snow..

Edited July 4, 2012 by damianslaw

[andymusic]

Bit of wishful thinking here, I was just wondering if there has been an instance where a pattern has changed in a stubborn pattern scenario and output has not picked up on it,Guessing it must be possible,In cases of hurricane activity or volcanic activity or something else.Would be interesting to know even better with detail.????

JT

Nothing like some positivity but - the metoffice have already heralded a fairly quiet season for hurricanes this year - so we may struggle to get anything like that to give us a pattern change - but we can but hope - I'd love a beautiful sunny week or two like we had at the end of May - to chill out in the garden - as it is with the models as they are the garden is beginning to resemble a tropical forest as it's growing at a fairly fast pace with plenty of rain and long daylight hours. We will all just have to keep our eyes peeled for the pattern change and signs of lovely high pressure!!!!!!!!!!!!!!!

[nick sussex]

The ECM output is an absolute horror show for decent summer weather with those Greenland heights forcing low pressure into the UK, the GFS is positively wonderful compared to it in its higher resolution as that at least brings a weakish ridge in .

The problem when you get stuck in this negative NAO rut is how quickly this ends, unfortunately the omens aren't good as these patterns once set are very hard to break down, in winter we do often see this becoming more west based at times and really this is looking like the last hope to salvage something for the UK this summer, if the core of those heights can transfer far enough west we might see troughing developing further west and north forcing some ridging ne towards the UK, though you need the right alignment to pull up that warmer southerly influenced flow, at least you manage some drier much warmer interludes.

For longer term summery weather of course the best option is the Azores high ridging ne and staying but that shows absolutely no sign of doing so at the moment.

[bluearmy]

the spreads on ecm and naefs promise nothing but depressions headed w-e. there is always the likelihood of a ridge here and there to give us a days respite but the overall pattern shows no sign of change for the next fortnight. i was mildly encouraged by the gefs 12z output but the 12z naefs doesnt reflect any possible improved outlook. at some point in the near future, if the ecm 32 dayer is going to be proved right re the last week of july, we should start to see some signs towards the end of naefs that something is changing.

[Bobby]

The NMM shows a washout few days for many

You can see how the air is being sucked up all the way from (warm dry) Spain/N. Africa. It mixing with the cool moist air around us is a recipe for trouble.

It looks like France and most parts NW of Europe are having a washout summer too.

[Jason T]

The ECM output is an absolute horror show for decent summer weather with those Greenland heights forcing low pressure into the UK, the GFS is positively wonderful compared to it in its higher resolution as that at least brings a weakish ridge in .

The problem when you get stuck in this negative NAO rut is how quickly this ends, unfortunately the omens aren't good as these patterns once set are very hard to break down, in winter we do often see this becoming more west based at times and really this is looking like the last hope to salvage something for the UK this summer, if the core of those heights can transfer far enough west we might see troughing developing further west and north forcing some ridging ne towards the UK, though you need the right alignment to pull up that warmer southerly influenced flow, at least you manage some drier much warmer interludes.

For longer term summery weather of course the best option is the Azores high ridging ne and staying but that shows absolutely no sign of doing so at the moment.

Hi Nick....Nice to see you post's. Winter must just be round the corner..!!! (It might as well be).An interesting bit of data i noticed a couple of days ago was the 0c isotherm not to far of the shores of Scotland which stunned me for this time of year,However taking everything in to consideration for this summer,temps etc i suppose its got plausibility. I suppose my next question is for all, If some of the current dire summer result is due to the Jetstream not high enough North,What stops it.???

Jason.

[k19]

Hi Nick....Nice to see you post's. Winter must just be round the corner..!!! (It might as well be).An interesting bit of data i noticed a couple of days ago was the 0c isotherm not to far of the shores of Scotland which stunned me for this time of year,However taking everything in to consideration for this summer,temps etc i suppose its got plausibility. I suppose my next question is for all, If some of the current dire summer result is due to the Jetstream not high enough North,What stops it.???

Jason.

Well at the moment the Jet stream is unable to climb northwards due to the troughing over the UK, and also the high pressure place over Greenland. Ideally to stop this the pressure situation in Greenland will change and the trough over us will warm out.

[Alex]

OMG is that an actual ridge appearing on the ECM 00z at 168hrs or do I need an eye test?

Maybe I don't, it disappears quickly!

[Jonathan Lang]

Noticed the high pressure over greenland significantly weakens and even becomes low from the middle to end of the ecm and gfs. Sign of change?

[Summer Sun]

GFS remains very unsettled this morning with no sign of high pressure building

http://www.netweather.tv/index.cgi?action=nwdc;sess=

ECM also shows no sign of summer again this morning

http://www.netweather.tv/index.cgi?action=ecm;sess=

And UKMO completes the set

http://www.netweather.tv/index.cgi?action=meto;sess=

[shedhead]

Noticed the high pressure over greenland significantly weakens and even becomes low from the middle to end of the ecm and gfs. Sign of change?

Might well be, but we've seen this kind of pressure fall signalled up there several times in recent weeks, only for the models to undo it as we move towards the more reliable timeframe. So mildly encouraging, but still to be taken with a liberal pinch of salt for now imo..

[Thunder Snow]

Atleast the 6z keep the heaviest and prolonged rain out of northern England

[Bobby]

It looks like a more southerly track for that heavy rain now more likely with central and eventually SW parts now more in the firing line.

GFS rain accumulations

ECM rainfall:

HIRLAM:

GEM/UKMO meanwhile take it a bit further North. More adjustments to come no doubt

Edited July 5, 2012 by Barb-

[Frosty.]

The Gfs 06z and Ecm 00z are showing a gap in the bad weather at around the T+144 to T+168 hour mark but it only looks like being a brief respite before yet more low pressure pushes in from the west and the southerly tracking jet looks like being maintained through to mid month and beyond so there is still no end in sight to one of the wettest summers for a while. There is a lot more rain to come this week with some flash flooding due to violent storms but some areas will remain dry with sunny spells, tomorrow it looks like an area of widespread torrential rain will move north across england and wales, reaching n.ireland and southern scotland later tomorrow and then continuing to spread north during fri night and saturday with the far north having persistent rain and fresh NE'ly winds throughout the weekend but brighter for most areas with further showers, then becoming drier and brighter towards the middle of next week as a ridge pushes east but low pressure will soon chase the ridge away eastwards, there is a possibility of hot continental air reaching southeast england later next week but that would probably just act as a trigger for more thunderstorms.

[Thunder Snow]

Where can you find the rainfall total mm chars?

[Bobby]

Where can you find the rainfall total mm chars?

Here http://www.meteociel.fr/modeles/gfs/accumulation-precipitations/72h.htm

Or http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=ukuk&MODELL=gfs&MODELLTYP=1&BASE=-&VAR=rsum&HH=72&ZOOM=0&ARCHIV=0&RES=0&WMO=&PERIOD=

You can also ind the rainfall total charts for other models on those sites.

[shedhead]

UKMO appear to be ignoring their own model and going with GFS on Sats rain warning in the SW.

Yellow Alert of Rain for South West England

Yellow Alert of Rain for South West England : Cornwall, Devon, Plymouth, Dorset, Somerset, Torbay & Isles of Scilly valid from 0005 Sat 07 Jul to 2355 Sat 07 Jul

Edited July 5, 2012 by shedhead

[jethro]

Oh goody. We've hardly had a drop around here for ooo, nearly 24 hours now.

[Thunder Snow]

The 12z seems to push the rain quickly south and west tomorrow, before moving into Scotland maybe some good news for northern England

[Geordiesnow]

Ever so slight tentitive signs that we may see heights lowering over Greenland to some extent which may allow the Azores high to trickle in from the SW although I would think any prolonged warmth and sunshine may be a tad far fetched at this stage.

No doubt we may see some variable outputs but if we can see the trend of heights lowering over Greenland somewhat and for the Arctic Dipole to weaken then we may enter a more normal UK summer weather pattern and not a pattern of slow moving low pressure systems stalled over us.

[Snowy Easterly]

i hope the GFS is onto something with the azores high ridging in, the UKMO and GEM are awful with a horrible northerly just in time for my birthday next wednesday