Model Output Discussion 12z 01/06/13

[johnholmes]

I know some have doubts about the guidance these charts give but to me they are about the best we can get, when used carefully, on the web. They show that all 3 main models that issue these type are quite solid with the upcoming pattern in the time scales shown on the 6-10 and 8-14 from NOAA this evening.

http://www.cpc.ncep.noaa.gov/products/predictions/814day/500mb.php

[nitro_deluxe]

Three hot days and a thunderstorm anyone?

Used to be two a penny in Summers of ye olde

[Alex]

Perhaps to be replied to me by PM or in the Summer 2013 thread to save clogging this thread up but what are your latest views in to the rest of summer? Surely not as bad as last year?

Hi Blizzards,

Mods can move this if they feel it is right.

My opinion on summer is still that it will be the warmest and driest summer since 2006 but if la nina develops then there is an increased chance of my initial thoughts going out of the window.

The problem we have now is that angular momentum has gone negative and the MJO is incredibly weak.

http://www.esrl.noaa.gov/psd/map/images/reanalysis/aam_total/gltotaam.sig.90day.gif

Both of these characterise La Nina development, I may be premature with my thoughts and more time is needed. My thoughts above look like the middle of June will be much more unsettled due to these Synoptics.

If we continue wiith neutral ENSO which is characterised by neutral AAM and a stronger MJO then there is an increased chance of a mid latitude ridge setting up somewhere, 2010 is a good example of this which set up over Europe in July and extended to Russia in August.

I hope I answer your question. If you have any other Qs then feel free to ask me on twitter - @alexbweather

Edited June 3, 2013 by Alex

[Cloud 10]

I know some have doubts about the guidance these charts give but to me they are about the best we can get, when used carefully, on the web. They show that all 3 main models that issue these type are quite solid with the upcoming pattern in the time scales shown on the 6-10 and 8-14 from NOAA this evening.

http://www.cpc.ncep.noaa.gov/products/predictions/814day/500mb.php

 

 

ECM and GFS ensemble mean charts for 10 days out are very close to each other with low pressure

just west of the UK,so looks like becoming more unsettled as the middle of June approaches,although

exactly how unsettled will depend on how far East the trough can get.

 

ecm..  gfs..

 

 

Some very pleasant weather to come before then though and looks like being the third nice 

weekend in a row coming up which is noteworthy in itself!

[Tony27]

18z is a horror show for this weekend, the heatwave is replaced by the oh so familar cool northeasteriles with heavy showers, dear oh dear 

[Carlrg]

http://176.31.229.228/modeles/bom/archives/2013060300/bom-0-240.png

 

 

The BOM's sending the lp over the top of us allowing the warmer weather and pressure to build over the south of the UK.

Edited June 3, 2013 by Carlrg

[Geordiesnow]

18z is a horror show for this weekend, the heatwave is replaced by the oh so familar cool northeasteriles with heavy showers, dear oh dear 

 

Whats more worrying for me is that last nights ECM showing lowering heights across Greenland have now gone and the models do seem to favor of having "yellow highs" over that area, never usually good news for us.

 

Hopefully the GFS 18Z is a little too quick in breaking things down, If the settled spell does break down, I rather it was more like the UKMO as there is more chance of pumping up some warm air before it finally leaves us, the 18Z will just end up cool and wet really. 

[summer blizzard]

GFS18z can be binned in my book, it's an outlier compared to the UKMO, ECWMF, JMA and GEM 12z runs as early as day 6.

 

[William of Walworth]

http://176.31.229.228/modeles/bom/archives/2013060300/bom-0-240.png

 

 

The BOM's sending the lp over the top of us allowing the warmer weather and pressure to build over the south of the UK.

 

That track would surely be the least worst outcome for many of us. But how valid is that scenario? Other models contradict it.

 

My main concern is not so much about any breakdown (which would hopefully happen after the weekend not during) but how temporary or not it is. Not looking forward to people 'writing off' June in its entirity, and I'm anxiously hoping for signs that HP influence might recover later. Few yet ...

[mushymanrob]

I know some have doubts about the guidance these charts give but to me they are about the best we can get, when used carefully, on the web. They show that all 3 main models that issue these type are quite solid with the upcoming pattern in the time scales shown on the 6-10 and 8-14 from NOAA this evening.

http://www.cpc.ncep.noaa.gov/products/predictions/814day/500mb.php

 

that chart though isnt too bad, warm but showery southerlies (showers more for the west), high anchored to our northeast...

 

well im not convinced there much of a thunderstorm risk this weekend, the far south/cornwall perhaps being favoured, but as the charts stand atm theres virtually zilch chance imho.

 

we have about another week (brilliant!) of mainly dry sunny warm weather (but not hot, its unlikely to produce widespread 25c+ , the higher uppers remain stubbornly over france), before the inevitable breakdown happens... now the big question will be, whats the nature of the breakdown? will it lead to another washout summer? will it return us to 'normal' june weather (mixed), will it be a temporary feature before more warm sunny settled returns...?... its too far off to be certain, but anything is possible at this stage.

 

btw... isnt it ironic that after a very cold spring, the first settled spell of the summer is also 'cold'? or should i say cooler then what a sunny high pressure regime in early june would normally be expected to produce?

Edited June 4, 2013 by mushymanrob

[Frosty.]

Smooth sailing from the Ukmo 00z this morning, long spells of sunshine all week and becoming very warm, locally hot towards this weekend with high pressure in complete control, the trough slides under the block and we import a more humid continental airmass and the risk of thundery showers would increase across the south, the way the ukmo is shaping up, next week would remain warm with no cooler atlantic breakdown.

Edited June 4, 2013 by Frosty039

[mountain shadow]

The GFS delays any breakdown until Wednesday next week also.

[Frosty.]

The Ecm 00z is a stonking run, high pressure and increasingly very warm & locally hot with plenty of sunshine and light winds, a hot and sunny weekend and the good news next week is the warmth and sunshine continues but with a more continental humid flow with a growing risk of scattered thunderstorms but still with lots of hot sun.

[Scorcher]

Yes a great run from the ECM this morning and great to see GFS has backed down from its idea of a breakdown early next week. Very positive runs for those looking for warm sunshine this morning.

[Gibby]

Hi everyone. Here is the report on the ever changing outputs from GFS, UKMO, GEM, NAVGEM and ECM for midnight today Tuesday June 4th 2013.There is still a general consensus between the models of dry and fine conditions prevailing over the UK between now and the start of next week with plenty of warm sunshine and relatively light winds, mostly from the East all due to High pressure drifting slowly away to the North of the UK. There is the risk of the odd isolated heavy late day shower each day but these will be the exception to the rule. There will be a cooling trend near the East Coast as misty low cloud invades from the North Sea affecting Central areas too in the early morning's.GFS then draws a thundery disturbance close to Southern Britain very early next week with a day or so of thundery rain or showers here. Then after a drier interlude under a ridge cooler and fresher Atlantic air crosses from the West midweek bringing rain and fresh breezes to all areas for a time. Thereafter, a more Atlantic Westerly based airflow pattern develops with some rain at times more especially in the North.The GFS Ensembles show a change to rather cooler and unsettled conditions look likely as we move into next week with temperatures returning to normal levels with rain at times.The Jet Stream currently flowing lightly well to the NW of Britain reinvigorates early next week on a West to East course towards France.UKMO shows Low pressure developing to the SW of the UK early next week with a potentially thundery breakdown of the weather looking likely. The thundery showers will be most prolific towards Southern and Western areas with the best of the dry and bright weather likely to the NW while the NE sees misty low cloud and cool conditions with a feed off the cool North Sea. Most areas will become rather humid but still warm in any brightness.GEM today also shows a threat of something rather thundery in nature for the SW of the UK while Northern and Eastern areas look at greatest chance of staying dry and fine. The progression towards a total breakdown of the weather is very half-hearted with some places still dry at the end of the run with any shower risk reserved mostly towards the West.NAVGEM brings a change to thundery showers more generally across the South early next week before they clear away East to leave a weak ridge over the UK with dry weather with sunny spells and average temperatures returning around midweek.ECM also shows a thundery breakdown from the SW early next week. The breakdown is hardly a clean one though with many Northern and Eastern areas remaining fine and dry for a good while with the SW seeing the largest changes where thundery rain would never be far away as low pressure develops close by at the end of next week.In Summary the models are still showing a lot of uncertainty in the course of weather events next week. Their struggle is built around their inability to chart how much the current high pressure area loses it's grip and to what extent any resultant Low pressure makes inroads into the UK. The best stab I can give it this morning is that it looks like the greatest chance of seeing a change to the current fine and warm spell is likely to be in the SW as all models look keen to bring at least a temporary spell of thundery rain in here early next week. They are much less keen to spread this on to other areas though later in the week with High pressure still nosing down from the North at times. Whatever happens it looks like the current gin clear skies will be replaced by hazy and more humid conditions with more cloud and poorer visibility from the weekend on. If ECM is to be believed a pretty wet spell could develop in the SW at the end of next week but this is just one of a variety of options shown for the UK by then.

[Weather Boy]

ECM and GFS ensemble mean charts for 10 days out are very close to each other with low pressure

just west of the UK,so looks like becoming more unsettled as the middle of June approaches,although

exactly how unsettled will depend on how far East the trough can get.

 

ecm..EDM1-240.gif  gfs..gens-21-1-240.png

 

 

Some very pleasant weather to come before then though and looks like being the third nice 

weekend in a row coming up which is noteworthy in itself!

 

Those charts don't necessarily indicate a breakdown, or at least not in the east/south-east.  Some of the more prolonged fine summer spells this country experience come from sluggish inactive LP systems in the mid-Atlantic throwing up warm continental air-masses ahead of them.

 

I for one have no idea how we can tell whether these systems chart their normal course over the UK and then on to Scandanavia, but sometimes they don't, presumably because they are bloked by the HP over the UK or Scandi/ northern Germany.  A half-way house is that they make some progress and then stall somewhere over Ireland, Wales, West Country, take your pick, bring hot weather to the eastern side and wet weather to the west.

 

That chart does not (at this point anyway) indicate a progress of the LP eastward and it seems to me that that may or may not happen.  The confusion of the models as to whether and when there is going to be a breakdown next week is presumably due to the uncertainty of this progress (if any) at this long time-range given that it looks like we are looking at at least 8 days ahead and probably 10.  The fact that some models were hinting at a breakdown as early as Monday and that this has been put back is arguably a good sign.

 

A breakdown is of course inevitable, but the question is when and whether there will be a HP re-build behind it.  It seems to me that currently the breakdown is too far away for the models to come up with a firm answer to this question, which means lots of fine weather to enjoy in the meantime whilst they search for an answer!

[summer blizzard]

It's notable that none of the models actually show a breakdown within the next 8 days, what they show instead is a relaxation of pressure and shallow low pressure making it through but not really defeating the warm air-mass (instead we get cloudy and humid most likely - the worst kind of weather). If your looking for a genuine breakdown then you have to look at the day 11 GFS..

 

[WheresTheSnow]

Looks to me as though the GFS 00Z has downgraded temperatures a little for Friday & the weekend, although I haven't viewed the ECM or UKMO, so Im not sure what temperatures their predicting.

 

Nevertheless, it still looks  pleasantly warm from viewing the GFS! 

Now we can't be complaining about that, can we. Bring on the heat!!!

[Frosty.]

Watch out for an area of sea fog (currently lurking in the north sea) rolling well inland from the north sea tonight which looks like making tomorrow a duller, mistier and cooler day for the eastern side of the uk (especially northeast england) but central, southern and western england and wales will again be warm and sunny with temperatures up to 23c 73f, scotland, away from north sea coasts also looks fine with sunny spells developing after a dull start in the east and north. From thursday, the risk of sea mist/fog/low cloud should slowly reduce and most of the uk is then fine and mostly sunny with just isolated heavy showers being sparked by temperatures soaring into the mid 70's F, and by the weekend we could be seeing temps close to 80f in parts of the south & east. Into next week the models currently indicate increasingly humid continental weather with hazy sunshine and scattered thundery downpours with temperatures remaining very warm and muggy.

Edited June 4, 2013 by Frosty039

[Carlrg]

The Atlantic train looks like it's waiting in the wings on the 00z.

Edited June 4, 2013 by Carlrg

[samadamsuk]

imo its only in lower resolution where the atlantic jet steams through - it's constantly splitting beforethat point, meaning an increasing continental influence for us, possibly with a stalling low to the SW, and some stormy conditions across the med coming up!

A fine start to summer - jsut need some humidity and storms now!

 

Sam

[Thundery wintry showers]

btw... isnt it ironic that after a very cold spring, the first settled spell of the summer is also 'cold'? or should i say cooler then what a sunny high pressure regime in early june would normally be expected to produce?

I think the anomalously cool North Sea will be having an effect on the temperatures (mainly near the east coast, but to a lesser extent inland).  That said, dry and sunny but relatively cool weather has historically been more common in June than in July and August.  The dry sunny Junes of 1989 and 1996 both had a mean temperature close to the long-term average with warm days offset by chilly nights, and that looks like being the main story during this coming week.

[Frosty.]

The Ecm 00z ensemble mean shows a slow leaking of pressure from early next week with a warm and humid continental type airflow over the uk with an increasing risk of thundery showers but also with good sunny periods, not much changes throughout next week, low pressure remains out in the atlantic and the uk continues warm and muggy with a thundery type feel and occasional thundery rain with torrential downpours.

[AWD]

A quick glance through various model output and data reveals much of the same really. An increasingly warm and sunny week ahead, rolling into the weekend too with a small chance of some thunderstorm development over southern most counties then and a slow (key word being slow) deterioration in conditions as we progress through week 2.

A look at the Operational output at 144 and the theme is broadly similiar;

A relaxation in SLP values and a trough to the west in the Atlantic trying it's best to push east, only doing so very slowly. By midweek, the ECM shows the trough just about succeeding, although losing some energy as it does so;

Something else to note is the noteable trend to increase heights to the north of the UK, with the option of these said heights then moving to either the north west or north east further down the line. The CFS raw output for July shows such a scenario, with Scandiavian heights to our NE and a trough to our SW, resulting in warmer conditions further north and east and cooler further south and west;

Just something to watch out for in coming weeks anyway, not too important for now. What we do have good agreement for is a trough to spawn in the mid Atlantic as shown by the 500mb anomaly charts;

This said trough slowly pushes against the current High Pressure cell we have over or close to the UK now. What is becoming an increasing trend IMO is for the trough to disrupt some energy under the block and south of the UK into Europe. This partly due to the Jet Stream realigning on a more southerly path as shown below;

Could it be that whilst the HP cell is bringing some summer weather now and this week, it could also assist in the cause of aligning the Jet Stream in a more southerly path in the future. Certainly been hints of a more southerly tracking Jet recently.

The EC Op this morning had some rather warm and humid conditons in it's latter part of it's run. A look at the EC mean output at 144 hours;

and again at 240 hours;

shows the Op may have been a tad to slow in pushing the trough further east towards the UK, thus enabling warm, humid air to be pumped north first. A look at the London ens;

show the Op to be at the warmer end of the temperature suite in FI and at the lighter end of the wind suite;

This both suggests the Op being on the slower end of proceedings next week with the favourable EC ensemble outcome more geared towards something a tad quicker and cooler. The rainfall suite also shows the Op to be one of the drier options;

So perhaps something a tad more changeable is to be expected next week?

The CFS v2 anomaly for PPN shows the dry week we are receiving this week;

with something more wetter favoured in week 2, hence the green colours returning. The 15 day Birmingham ens show temperatures to peak at around the mid 20c's at the end of this week before falling back towards average or perhaps slightly below next week;

The 32 day suite also maintaining the slightly below average temperature theme through the mid month period;

Rainfall projections for Birmingham look to increase towards average values next week, and persisting along this line through the mid month period;

A more unsettled theme clearly evident there, as it is for the GEFS for London;

and for Cumbria;

Temperatures for both London and Cumbria again cooling off after the warm weekend period;

So IMO, all signs are still there for something more changeable to commence next week after what is going to be an increasingly warm and sunny weekend this weekend, with just the small chance of some thunderstorm activity down south. The latest 84 hour FAX shows a front near NW France;

which could indeed provide the possible thunderstorm activity if indeed it comes up towards the UK. The 96 and 120 hour FAX charts published tonight should be an interesting view.

To summarise, a slow breakdown is still looking likely after viewing all this mornings data collectively, with a return to more average temperatures and showery conditions after the upcoming warm weekend. Long term model and ensemble guidance does indicate the more changeable pattern to persist through mid month, but as ever with long range modelling, things do change, so take this lightly.

I do think that most (not all but most) of next weeks projected rainfall will fall in a more showery and convective nature rather than frontal so some pleasent days inbetween said showers are still possible.

Edited June 4, 2013 by AWD

[SteveB]

That sounds perfect, I don't mind an unsettled period as long as it stays warm!