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Polar Maritime

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

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The GFS has been very consistent with it's modelling for next week. Azores high ridges in and sends low heights packing into central Europe with dry and increasingly warm weather developing until the weekend, when some sort of troughing comes in from the north west. Similar to this week in some ways. Is it consistently wrong though?

If that day 5 chart from the ECM verifies then we might as well close this thread as having multiple cut off lows and cold pools in the European locale alone would making getting even remotely close to the correct solution near enough impossible.

Will find out tomorrow where the models will go. I will admit that I did expect a backtrack from the GFS to an extent, but it hasn't budged at all.

Ecm has been the leader of late..... :cc_confused:  :nonono:  :closedeyes:

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Ecm has been the leader of late..... :cc_confused:  :nonono:  :closedeyes:

Well this was the day 4 chart from yesterdays ECM

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Low pressure over the South of the UK with a sharp trough aligned through the UK. Reliable time-frame, there and there abouts. Right?

 

Todays T72

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Trough much weaker with a low developing over central Europe. That's a big change for a model which should be rock solid at that time.

 

GFS yesterdays T96

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Todays T72

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Near identical. As much as the GFS is bashed, you have to admire the resolute consistency here whilst other models have struggled. 

Very strange to see this though I must admit. The roles are usually reversed.

Edited by Captain shortwave

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Most models apart from GFS supporting trough dominance as we move through next week. The azores high looks like it is going to struggle to ridge sufficiently NE thanks to active trough action to our NW, and with strong heights locked in place to the NE, the trough has nowhere to go other than settle itself over the country before moving towards Germany. The main player is the strength of the jet - it is firing into gear at the moment. A weaker jet would enable the azores high to build NE and quite possibly link with heights to the NE - with all the promise this would spell for heat lovers..

 

Alas, we are in a very different position to this time last year, when the jet was sent packing way to the north and we saw the azores high build NE ushering in a spell of wonderful summer weather.

 

I have said before, this is a pivotal point in the summer, the way the jet behaves now often prevails in similar state throughout the rest of the summer, it traditionally stirs now after its spring slumber.

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There is a change of emphasis with the 500mb anomalies this evening apart from the GFS for next weekend. NOAA has moved the trough slightly west although still affecting the UK  The ECM is similar but the GFS isn't so keen to shift it from the UK. So rather than a NE/SW warm air linkage there is a NW/SE cooler air linkage with the cooler air over Europe.The Azores high taking a back seat to the west forcing the jet to curve around into a southerly route into n. Europe.

 

With the ECM ens this leads to a large slack low pressure area in the eastern Atlantic stretching into Europe with the N and NE coming under the influence from the warm air to the NE leading, for a change, to the warmer temps being in those regions.

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Edited by knocker

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Ecm has been the leader of late..... :cc_confused:  :nonono:  :closedeyes:

 

Which is good because the latter stages of the ECM 12z mean show the heat building and pressure rising from the south.

 

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Marked change in the GFS 500Mb anomaly from 12z yesterday for next weekend. The trough is now in a similar position to the NOAA and ECM having moved west to mid Atlantic resulting in a similar surface synopsis of a large slack area of low pressure over the eastern Atlantic and n. Europe. Temps in the UK should be slightly above average.

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Edited by knocker

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Was just thinking how the influx of warmer uppers from the east sets up an above av temp spell from next weekend ( though not nec settled) and the ecm op doesnt even get the warm front past the east coast!

Btw, all the ops are pretty poor at the moment. None deserve any special credit although gfs' persistence in pushing the high heights ne from the azores across the uk does seem to be odd. Ecm has picked the energy coming in from the nw although it hasnt managed to work out the resulting pattern. I guess a cut off upper trough causes headaches!

Edited by bluearmy

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Was just thinking how the influx of warmer uppers from the east sets up an above av temp spell from next weekend ( though not nec settled) and the ecm op doesnt even get the warm front past the east coast!Btw, all the ops are pretty poor at the moment. None deserve any special credit although gfs' persistence in pushing the high heights ne from the azores across the uk does seem to be odd. Ecm has picked the energy coming in from the nw although it hasnt managed to work out the resulting pattern. I guess a cut off upper trough causes headaches!

 

Yes a bit of a bummer that.

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Latter stages of the ECM ens show the chances of the Atlantic trough/downstream euro ridge scenario to be increasing. That may explain the higher london temps on the graph by mid month. What has so far been a decent summer may be about to take a turn for the even better. ??

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The route to something very warm or even hot is starting to appear around the week 2 range. The low which crosses the Atlantic at the end of the coming week is stalling around the Iceland region, Its presence eventually allows troughing to develop in the Atlantic as it phases with a new low coming off the Newfoundland coast. This causes a new upper ridge to build over Iberia which will allow heat to push up from the south.

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We need the low over Iceland to phase with the system upstream to allow a ridge to develop. Of course we could easily see the energy there drain south eastwards keeping the fairly warm but mixed conditions over the UK.

Edited by Captain shortwave

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Given the lack of support it was inevitable for GFS to backtrack on the midweek ridge, meanwhile its looking pretty warm in Scandinavia

 

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Pretty chilly in the SE under the rain

 

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Overall the week looks like seeing a mix of sunshine and showers but a chance of some more persistent rain in the east on Wednesday and Thursday

 

After a dry start showers get going during late morning some could be heavy and thundery during the afternoon

 

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Tuesday again sees showers developing maybe a bit more scattered than Monday but some could again be heavy and thundery

 

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By Wednesday the focus shifts to parts of the east with some more persistent rain possible and temperatures really struggle with highs in the low teens for the SE drier else where

 

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By Thursday its parts of the east again which sees the most persistent rain chilly under the rain with temps in the low teens for some

 

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By Friday the showers become more isolated with Kent most at risk of catching some heavy and possibly thundery showers with temperatures here in the mid to high 20s low to mid 20's widely

 

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GFS 6z has all the building blocks in place for a potential hot spell. Low pressure stalling over iceland, blocking high over Scandinavia and a the Azores high pushing up from the south west. Game on!

 

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looking at the extended ecm ens, it appears that a nw europe mid month plume is on the agenda. too early to have a strong opinion on its longevity or how likely it is to get as far north as here although this atlantic troughing is not a new idea.

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The Polar Vortex certainly seems to be tightening up at last towards the end of the run, With High Latitude blocking fading away. Something that has been prominent during Spring and the start of Summer so far..

 

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Edited by Polar Maritime

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I thought the yes no to next week's possible ridge was nearly resolved yesterday, however it remains in the air. The GFS 0z op is anti-ridge but the Control is pro-ridge:

 

post-14819-0-01079100-1404640399_thumb.p  Mean just favouring ridge though very close on the GEFS: post-14819-0-78344700-1404640467_thumb.p

 

Even if there is a ridge it is a brief affair. So despite the postings suggesting this is resolved I am not sure. Looking at the 5 day ECM postage stamps it is apparent that they are also split. The op and control are not in the main cluster and many show a stronger mid-week ridge.

 

Maybe a mix between the two, like GEM: post-14819-0-67408800-1404640753_thumb.p UKMO closer to ECMpost-14819-0-90894500-1404640821_thumb.g

 

As you can see from the 06z run the transient mid-week ridge is back again: post-14819-0-70979300-1404641402_thumb.p

 

I also still believe the models struggling to handle the energy from the ex-tropical storm Arthur. GFS and ECM handle the remnants differently; 2am July 10th:

 

ECM: post-14819-0-43475600-1404641858_thumb.g  GFS 06z: post-14819-0-22285200-1404641878_thumb.p

 

ECM pushes the low into the jet and pumps it up, promoting a more meridional pattern. At T120 the low is 1000mb whereas the GEFS mean is 1010:

 

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As the GFS op has the low less intense it allows the Azores to ridge into the SW again earlier than on the ECM. That Atlantic trough at D6 on both GFS and ECM  certainly looks a static feature for at least 3-4 days as the Atlantic has slowed and blocks to the east and south keeps it in situ. In the end the 06z fires up the Atlantic as the upstream flow goes flatter and we enter into a N/S zonal split for the rest of the run:

 

post-14819-0-32573900-1404643112_thumb.p  post-14819-0-52760100-1404643148_thumb.p

 

The GEM mean does not support the ECM at D10 with regard to the strength of height anomalies so this may again be due to the ECM bias:

 

GEM Mean:  post-14819-0-36385100-1404644014_thumb.p  ECM mean: post-14819-0-16463200-1404644224_thumb.g

 

If ECM is wrong with either the intensity of the Iceland low or the ridging mid-week then it's latter FI attempts to build the Euro ridge may be unfounded, and of course the whole suit will be skewed as the op has good support from its members. I can see why the models are performing poorly, lots of uncertainty.

 

 

 

 

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Although the risk of rain / showers can't be ruled out at first the ECM ens shows some warmer air moving in from the east by Friday

 

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This then lasts through-out the run with nowhere seeing 850's below +6 with the south under +10's at the end of its run

 

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GFS 06z gives us a very warm weekend with some thundery rain too

 

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The GEM mean does not support the ECM at D10 with regard to the strength of height anomalies so this may again be due to the ECM bias:

 

GEM Mean:  http:////f1.nwstatic.co.uk/forum/public/style_images/tctc91_simplify/attachicon.gifgens-21-1-240 (2).png  ECM mean: http:////f1.nwstatic.co.uk/forum/public/style_images/tctc91_simplify/attachicon.gifEDM1-240.gif

 

If ECM is wrong with either the intensity of the Iceland low or the ridging mid-week then it's latter FI attempts to build the Euro ridge may be unfounded, and of course the whole suit will be skewed as the op has good support from its members. I can see why the models are performing poorly, lots of uncertainty.

 

 

I'm not sure how much we should be reading into the GEM really as brought to my attention by Knocker in the model banter thread:

After cooking along for almost 8-months, Canadian global model 5-day skill for NH has hit the skids. pic.twitter.com/WPrzjuAxan

 

I suppose it could have improved again. I'd certainly take the ECM over it any day though, especially as in comparison it still tops the verification stats on average, despite whatever bias it has (I have seen a graph somewhere that showed the GFS has nearly as much 'height bias', whereas the GEM/UKMO were at the other end of the scale with interestingly no models near the centre with neutral bias)

The ECM ensembles have been quite consistent with this trend towards day 10 and the op gets there too, though the op seems a bit different compared to other models for this week.

GFS ensembles (00z) have trended towards this compared to their previous runs

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and the mean certainly isn't poor:

http://www.wetterzentrale.de/pics/MT8_London_ens.png

(These will probably update to the 06z ensembles soon)

Would this supposed bias always lead to higher pressure predicted over the UK than occurs? what's to say it wouldn't lead to the ECM overdoing high latitude blocking which forces lows further south towards the UK?

 

As you say there seems to be a fair amount of uncertainty around, and perhaps slack pressure patterns.

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^^^ Looking at the ECM D10 verification for the last 4 0z runs they are performing terrible. GFS are also below the 30 day average for the last 4 runs but the ECM has reached new lows; last three into negative!!!

 

post-14819-0-19644600-1404647213_thumb.p The 12z nearly as poor: post-14819-0-72081000-1404647456_thumb.p

 

So I am now taking D10 charts from ECM at the moment with a pinch of salt.

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^^^ Looking at the ECM D10 verification for the last 4 0z runs they are performing terrible. GFS are also below the 30 day average for the last 4 runs but the ECM has reached new lows; last three into negative!!!

 

http:////f1.nwstatic.co.uk/forum/public/style_images/tctc91_simplify/attachicon.gifcor_day10_HGT_P500_G2NHX (2).png The 12z nearly as poor: http:////f1.nwstatic.co.uk/forum/public/style_images/tctc91_simplify/attachicon.gifcor_day10_HGT_P500_G2NHX (3).png

 

So I am now taking D10 charts from ECM at the moment with a pinch of salt.

Probably because the ECM was repeatedly going for Scandi trough for the week just gone, the flatter solution verified as the south east experienced with conditions turning very warm for a couple of day. Hence also why the GFS is faring a little better.

The ECM solution for week 2 makes sense, if the low stalls over Iceland you would expect a trough in that vicinity to develop in due course which would correlate to a Euro ridge developing with the potential to affect the UK as well.

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Mmm reliable timeframe is quite short at the moment. Models are struggling, we are only now seeing them latch onto a strong trough development to our east come mid week ushering a possibly very wet cool day in the east on Wednesday. It is a tricky set up to predict with the UK in a bit of a no-mans land at the moment almost 'col' situation, with strong heights to the SW and NE and low heights to the NW and SE.

 

Expect the models to continue to play around with developments as we move into the middle part of July and what traditionally marks the start of 'high summer'. There are tentative signs though we could see a strong trough developing over east atlantic thanks to a stronger core of low heights within the polar vortex, this would have the effect of allowing a strong ridge to develop over Spain/France and with both the azores high and scandi high in place - it could set up the first proper very warm spell of the summer.. but this is some way off and developments next week could easily scupper such an evolution.

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The Polar Vortex certainly seems to be tightening up at last towards the end of the run, With High Latitude blocking fading away. Something that has been prominent during Spring and the start of Summer so far..

 

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Low resolution but its about the time you see the -10 isotherm reappear.

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Thursday's low further east on UKMO's 12z run

 

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Yesterdays 12z

 

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Bar the odd isolated shower Friday looks drier for all

 

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GFS for Thursday

 

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Edited by Summer Sun

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Certainly a trend this afternoon to weaken low heights more substantially as the week progresses, still Thursday looks pretty bad for the East.

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Probably some heavy rain with some disappointing temperatures, probably high teens. Worst case scenario is the ECM tonight.

There are signs of a ridge from the Azores across all models into week 2 as low heights phase in the Atlantic to finally give a better shot of more substantial warmer and drier weather.

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Probably overdone but positive signs across all models tonight. Looks like the ECM is on a day9/10 heat quest tonight.

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The ECM has indeed been here there and everywhere recently, but this is not a totally unlikely endgame scenario when there is a Scandi High and Azores High - eventually, the Atlantic gets blocked to our west, and at this time of the year, that means a dry, hot southerly:

 

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GFS ens mean for the same time: less Scandi High influence so flatter pattern (though not totally dissimilar). As I said yesterday, I would usually back the ECM when it comes to Scandi High developments

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