Model Output Discussion - 30/6/2014 Onwards - Covering July.

[knocker]

Today's anomaly outputs seem to have the upper pattern pretty much nailed down so confidence fairly high on the surface analysis. I'll tale a rain check on how this will progress but just to say as the upper trough weakens the GFS is bringing the Azores high in as a major player.

 

 

[ANYWEATHER]

Both ecm and gfs  show a decline in pressure from now to more unsettled conditions,allbeit a rather slow change between now and day 7 or T+168. What both models show is a drop in temperature but nothing to drastic.....  Further afield ,it looks  like low pressure will be in control .............

[phil nw.]

Whilst the next 48hrs sees fresher Atlantic air spreading south east more widespread cooler and unsettled conditions are likely towards the end of next week in fact.

Until then it's promises to be more typical of average UK Summer weather,always warmer and brighter in the south with only small amounts of rain here.

Temperatures are still modeled to be in the low/mid 20'C for some areas.

It does look a lot cooler for much of Scotland and N.Ireland with more cloud and showery rain at times although certainly no washout.

The GFS ens means for next weekend- day 8- highlights the upper trough with that dig of much cooler air to all areas.

When compared to the setup currently( on the left image) we can see the change expected later next week.The Azores High which has been nearby for the last few weeks then much further away to the west.

 

 

The 500hPa forecast from the CPC site also modeling the upper trough over the UK in a few days time

 

Temperatures towards the end of next week would return much closer to normal that's for sure with a more unsettled spell looking more likely now as we enter August.

 

 

[Cloud 10]

NAEFS very keen to rebuild high pressure over Scandinavia after the generally cooler

and unsettled spell,which has been a familiar sight this summer.

 

[Man With Beard]

While I do not deny that D7 onwards looks a bit unsettled for a while, I would say buy a brollie but don't cancel the wedding just yet! A lot can happen when charts are at T168 - once they get to T120ish, then we can start talking about them as 'nailed', particularly in a low pressure dominated scenario. And the fact that most of next week will be sunny and warm i.e. not unsettled is being forgotten?

[phil nw.]

While I do not deny that D7 onwards looks a bit unsettled for a while, I would say buy a brollie but don't cancel the wedding just yet! A lot can happen when charts are at T168 - once they get to T120ish, then we can start talking about them as 'nailed', particularly in a low pressure dominated scenario. And the fact that most of next week will be sunny and warm i.e. not unsettled is being forgotten?

Some decent weather about especially further south in the next few days rjbw- as i alluded to in my earlier post.

 

Ensemble modeling has been pretty consistent with the upper air forecast and the developing trough by end of next week.

Hopefully the GFS mean for 10-15 day period is on to something with a rebuild of the Azores High

[Man With Beard]

Some decent weather about especially further south in the next few days rjbw- as i alluded to in my earlier post. Ensemble modeling has been pretty consistent with the upper air forecast and the developing trough by end of next week.Hopefully the GFS mean for 10-15 day period is on to something with a rebuild of the Azores High

Apologies Phil, you did mention that. Anyway, GFS 18z 'pub run' must have been reading my post, it really does drag out the best of the situation from a summery perspective, warmer uppers next week and the trough never makes the SE!

[Polar Maritime]

Again the GFS is showing unsettled cooler weather pushing in from the N/W by next Thursday, This theme continues through-out it's run, With Heights trying to push up into Greenland disrupting the Vortex. The ECMWF also shows this broad pattern, With the Atlantic notching up a gear. Quite an unsettled spell coming up, Compared to what we have endured over the past few Weeks. As I said yesterday, It will be interesting how the Models toy with this. And how stubborn the pattern will be.

 

Edited July 26, 2014 by Polar Maritime

[mushymanrob]

While I do not deny that D7 onwards looks a bit unsettled for a while, I would say buy a brollie but don't cancel the wedding just yet! A lot can happen when charts are at T168 - once they get to T120ish, then we can start talking about them as 'nailed', particularly in a low pressure dominated scenario. And the fact that most of next week will be sunny and warm i.e. not unsettled is being forgotten?

 

looks fairly unsettled to me sir, a reasonably mobile westerly isnt what i thought was 'settled'.

 

 

but its not looking bad, well not yet anyway. as has been monetioned 'average' for late july/early august isnt unpleasant weather at all most of the time and its not looking like the wet spells will be very wet at all. (owing to the current track of the atlantic lows being further north)as for the re-building of the scandinavian high , it wouldnt surprise me. theres been a high over there for most of the year. indeed if the azores high wasnt so close earlier in the year it might well have delivered a 'beasterly' in february. so another more settled sunny spell might be on the cards by mid august IF the forthcoming pattern doesnt establish.

Edited July 26, 2014 by Polar Maritime
To remove personal Weather preferences, Which are not Model related.

[Man With Beard]

looks fairly unsettled to me sir, a reasonably mobile westerly isnt what i thought was 'settled'.

 

brack4.gif

I'm thinking what things will look like on the ground, and most things I've seen suggest mainly dry and sunny at least Tues-Thurs. Scotland excepted. Though everything does seem slightly less settled this morning, e.g. UKMO/GFS heights are less strong.

[Milhouse]

Looks like a cooler wetter start to August is gathering support. Thereafter there are signs from the ENS mean of high pressure having more of an influence as we move into the 2nd week of August.

 

[Summer Sun]

Looking at GFS I don't see anything worse than average temperatures for the vast majority of next week for the bulk of England and Wales with Tuesday and Friday both showing temperatures in the mid 20's for some parts of western Scotland though could really struggle next week at times with temperatures in the low teens at best

 

Monday sees temperatures widely in the high teens to low 20's with just isolated showers

 

 

Tuesday has temperatures widely in the low to mid 20's north west Scotland struggles though in the low teens

 

 

Wednesday again has temperatures widely high teens to low 20's possibly mid 20's for some southern parts, again very little rain for England and Wales, western Scotland again struggles though with temperatures struggling to get into the low teens for some

 

 

Thursday again sees temperatures in the high teen to low 20's but once again western Scotland again struggles though with temperatures struggling to get into the low teens for some, showers / rain more widespread

 

 

Friday sees temperatures ranging from the high teens to mid 20's some heavier rain around for the afternoon

 

 

And finally next Saturday sees temperatures widely in the high teens to low 20's

 

[William of Walworth]

William, the broad scale pattern is decided by the upper air pattern. This has for 3 if not 4 days now suggested less settled than for some time.

Take a look at the Extra 500mb chart or its 850 mb for the UK in this case; check that GFS/Extra agree with the upper pattern being predicted by the anomaly charts. If they agree, not necessarily totally, then you can start to take GFS/Extra charts out to 240h as a reasonable idea of what to expect at ground level.

Obviously it does not always work but whatever season if gives a more reliable and less constantly switching idea of what is most likely-honest!

All points taken John, you are right of course. I hadn't had time to properly check all the models when I posted my 'hopecasting' post yesterday. Signs/support definitely growing now for quite an unsettled spell for many around next weekend, but the devil will still be in the detail, I suppose its not impossible that the strength of the trough  might still get reduced somewhat, but the likelihood definitely seems against that for the moment.

Trying not to pin too many hopes for now on POSSIBLE signs in some models of a rebuild of pressure later on into week 2, but those signals will still be worth monitoring  over future runs to see if they remain/strengthen/disappear/get contradicted.

For summerlovers, whether or not the upcoming trough-influenced weather lasts or is just more transient could make a big difference. I'd caution against assuming anything one way or the other for now, usual FI caution applies -- In other words neither write August off nor assume the month will be cool and damp throughout .... 

[SteveB]

Well next week isn't looking to bad, not a write off by any means. Yes it turns cooler, but that's not such a bad thing as the temps return to a more pleasant low to mid twenties for the South of the UK  &  high teens for the North of the UK.

 

Rain amounts look low for all next week, so not a wash out.

 

All in all, another usable week.

 

 

 

Edited July 26, 2014 by SteveB

[knocker]

Morning update on the GFS and ECM anomalies. Not much change with the upper trough dominating next weekend. The ECM is currently translating this into a more intense cyclonic surface interpretation. both giving below average temps. How this will evolve, assuming this is correct, is of course still open to doubt although both the GFS and ECM weeklies are suggesting with the weakening of the upper trough a more westerly flow will become established with the Azores high playing a more prominent role in the mid and eastern Atlantic.

Edited July 26, 2014 by knocker

[Tamara]

Posted by Tamara תָּמָר on 11 July 2014 - 13:25 in Forecasting Model Discussion

So there remains no sign of any classic summer-time fully fledged mid latitude High solution to bring

prolonged settled weather, but still plenty of very warm conditions amidst the showers and rain from

time to time, especially in the south and east of the UK.

In that sense, no real break from the dominating average to warm background pattern we have seen so far this summer.

--------------------------------------------------------------------------------

I apologise for the way this post has formatted, but I am typing on an unfamiliar small laptop that has presentation format ideas of its own!! It also accounts for the lack of charts and graphs I would usually post in support of

these updates

So, its been a while since the last update, but that concluding extract from

the previous posted update sums up reasonably well what has transpired over the last two weeks or so.

That said, one can certainly argue that classic summer weather in the UK (according to popular taste on this forum) has in fact occurred, in the form of an abundance of storms and heat.

Any southern European drought style dry-heat that 'classic summers' like 1990

and 1976 provided through the persistence of mid latitude high pressure belts stretching from the Azores into Europe has not been able to take a foothold this

summer so far for any especially long period of time

Both 1976 and 1990 'classic' summers, despite their intense heat, had a low

occurrence of thundery outbreaks.

So, the first half of this summer has been defined by a very cyclical pattern rather than any one dominating pattern courtesy of any one strong coherent background signal. The overall background 2014 summer pattern is about to complete another full circle and return to the retracted High pressure anomaly in the central/western atlantic and downstream trough that was witnessed some month or so back.

Why is this the case? The background disconnected (ocean to atmosphere) El Nino pattern continues to support this retrogreesive pattern phase recurring in tandem with monthly tropical thunderstorm wave orbiting (the MJO).

This stubborn disconnect has prevented 2014 summer patterns from evolving into

any full blown summer heatwave drought conditions (such as seen in 'classic

summers' like 1976 and 1990). The Pacific jet stream amplifying regularly

courtesy of a sequential +EPO signature (High pressure anomaly on the US Pacificwest coast)that periodically pulls our downstream mid latitude ridges west from time to time and sends colder air into the US, shifting the Jetstream back south. This sequence is well advertised in the 10 day modelling and the downstream effect of it is to retrogress the pattern and prevent any longer

term establishment of Scandinavian and Azores ridges that have also been a temporary cyclical feature of this summer. Low pressure in the atlantic hereby has been cutting-off and leading to the plumes we have seen (one in early Mid June and of course the other much more notable one in the last week or so).

The most recent plume was accurately picked up from around the first to second

week of July but has proved to have had more longevity than expected at that time. However, the change as anticipated cyclically thereafter and as highlighted in the previous post earlier in July is finally occurring from this weekend.

We should therefore expect a warmer version of the last UK trough dominated/

more unsettled spell, but should watch in the models in the coming days for the

pattern to keep evolving and changing towards a flatter atlantic profile as

energy transport across the NH manifested through effects of changes once more

in the Pacific jetstream filter downstream.

The upstream atlantic high pressure should eventually de-amplify in response,

with a shift in troughing orientation towards the NW of the UK introducing a more tropical maritime influence following the slack NW'erly, and rather weak,

polar maritime phase of the coming week.

This should encourage something of a NW/SE split in the weather after a more

generally changeable spell around next weekend.

What about after that? More cyclical evolution to come as a downstream ridging

response occurs following the increased energy upstream and extends from the

south west to settle things down again further south. A good chance that such an eastward moving ridge may in turn extend into Europe/Scandinavia as per recently and coincide with a split energy in the atlantic and hence another cut off low to engage the next plume perhaps towards mid month.

Edit: The amplified US West Coast pattern clearly indicated in the Pacific jet stream model forecasts as the next +PNA spike occurs and no coincidence the models are accordinglyretrogressing the downstream atlantic pattern

[url=http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/pna.sprd2.gifhttp://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/pna.sprd2.gif]http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/pna.sprd2.gif[/url

NAEFS anomalies show repeat cyclical signal for cut-off low to occur from main upper trough close to the UK, as discussed above, during week two and perhaps invite a next plume?

http://modeles.meteociel.fr/modeles/gens/naefs/run/naefs-0-0-168.png?0

Edited July 26, 2014 by Tamara תָּמָר

[Summer Sun]

GFS showing some very warm days for next week

 

Tuesday is the first with temperatures possibly hitting 28c in parts of the south mid 20's for widely for England

 

 

Wednesday temperatures drop slightly but the south coast could still hit the mid 20's

 

 

By Thursday temperatures are on the rise again for England mid to high 20's for most of central and southern england

 

 

Friday again is another very warm one with temperatures widely in the mid to high 20's for england

 

 

Next Saturday also looking rather warm for England with some heavy rain around

 

 

So bar Monday and Wednesday its looking quite warm still next week for England

Edited July 26, 2014 by Summer Sun

[Man With Beard]

GFS showing some very warm days for next week

 

Tuesday is the first with temperatures possibly hitting 28c in parts of the south mid 20's for widely for England

 

 

Wednesday temperatures drop slightly but the south coast could still hit the mid 20's

 

 

By Thursday temperatures are on the rise again for England mid to high 20's for most of central and southern england

 

 

Friday again is another very warm one with temperatures widely in the mid to high 20's for england

 

 

Next Saturday also looking rather warm for England with some heavy rain around

 

 

So bar Monday and Wednesday its looking quite warm still next week for England

Thanks Summer Sun, the reds/yellows speak of a north/south split, certainly cooler in Scotland but in the south, I think your average man on the street will think he/she we are still in the same heatwave. Saturday though... this is where the fun starts. Do I detect a push up from the south ahead of the incoming low? I wonder if this will develop a little more?

[IDO]

Thanks Summer Sun, the reds/yellows speak of a north/south split, certainly cooler in Scotland but in the south, I think your average man on the street will think he/she we are still in the same heatwave. Saturday though... this is where the fun starts. Do I detect a push up from the south ahead of the incoming low? I wonder if this will develop a little more?

 

 

As nice as the GFS 12z op run was for temps it was an outlier for next week:

 

 

Taking the mean the south should still have above average temps. Though of course it may be prudent to follow the hi-res runs at this range. GEM suggesting around 24c for highs in the SE for 3-4 days next week.

 

ECM still in line with the lowering pressure at the end of next week:

 

D6:   D7: 

 

The GEFS are still indicating a pressure rise from the SW around Week 2 of August. The mean at T300:

 

 

So a N/S divide next week, cooler than average up north, still above down south, but cooler than of late  Then 5-7 days of a cooler/wetter regime UK wide before maybe a warming from the Azores for week 2 in August.

[Polar Maritime]

The GFS is showing high pressure pushing well up into Greenland on tonight's run, Pulling the Lows from the West off the Atlantic further South over the UK. It does show things flattening out a little again towards the very end of the run..

 

Edited July 26, 2014 by Polar Maritime

[bluearmy]

Tamara's post says it all really. 'Rinse and repeat'. Even the model evolution is similar approaching the cycle. so it will get worse, but prob not as bad as it looks currently and then better again though margins of error on exactly where the retrogression gets to does allow for it possibly not being as broadly pleasant as the last cycle.

[mushymanrob]

Tamara's post says it all really. 'Rinse and repeat'.

 

with all due respect to tamara, (whos insight is far greater then mine), the question that springs to my mind is 'why'? ... now its true that so far this whole year the azores and scandinavian highs have been big part players in our weather, stuck between both systems. and IF the cycle continues then further down the line we might get another shot at something hot again.but this pattern/cycle will not last forever, sooner or later it will be broken and another will emerge. so from my pov (a rather ill informed one) im not so confident that these highs will again be major influences on our weather, especially the scandinavian high as i dont know what has caused high pressure to dominate our northeast this year. is whatever has caused that still in place?

[draztik]

This has definitely been quite a summer for our Scandinavian friends. GEFS shows this 'rinse and repeat' well this morning. Heights to our NE being squeezed by lowering heights to our N. Troughing, for a while looks to dominate proceedings for the UK, while heights rebuild to our NE, pushing further west into wk 2. The UK looks to "benefit" again, by being on the fringe.

GEFS height anom/ days 1-16

[SteveB]

Well this week coming isn't looking to bad at all. The further North you go the cooler it gets.

 

Rain fall looks low, and I would be surprised if I saw any rain at all.

 

Not a bad out look at all..

 

 

 

 

 

 

FI turns more unsettled (but doesn't it always)

[Man With Beard]

This has definitely been quite a summer for our Scandinavian friends. GEFS shows this 'rinse and repeat' well this morning. Heights to our NE being squeezed by lowering heights to our N. Troughing, for a while looks to dominate proceedings for the UK, while heights rebuild to our NE, pushing further west into wk 2. The UK looks to "benefit" again, by being on the fringe.

GEFS height anom/ days 1-16

Good spot drastik, and with the models traditionally struggling with blocks to the east, next weekend's evolution remains in the balance - on the one hand, GEM brings in a monster low, while GFS again holds the low up, keeping it hot in the SE on Friday and Saturday - which is interesting in itself as GFS is often the more progressive model. UKMO slightly closer to GEM, ECM in the middle but the trough never clears east of the UK, keeping most of us on the warmer side.