Model Output Discussion - 05/01/2016 18z onwards

[johnholmes]

Just now, carinthian said:

Well done John, now I know what you do with your Sunday mornings ! Looks like your thinking the same way of UKMO this morning. One of the Euros/UKMO or GFS will have to eat humble pie sooner or later. Its been great watching the models this weekend. Have to take rest now away from the computer and take my wife for a ski and lunch in the sun. Wish you were with us !

C

jammy sod

[Timmytour]

There's plenty of references to colder drier weather being good for drying out the flooded areas.  But genuine question,,,,  does the extent of cold currently modelled reduce the impact of the weather itself being drier?  Is it better to have mild southwesterly winds with periods of lighter rain interspersed with drier spells?  Can a spell of frrezing weather after floods end up causing more damage by freezing and expanding moisture in places where that moisture was not supposed to get into?

Edited January 10, 2016 by Timmytour
spelling

[bluearmy]

1 minute ago, Timmytour said:

There's plenty of references to colder dryer weather being good for drying out the flooded areas.  But genuine question,,,,  does the extent of cold currently modelled reduce the impact of the weather itself being dryer?  Is it better to have mild southwesterly winds with periods of lighter rain interspersed with dryer spells?  Can a spell of frrezing weather after floods end up causing more damage by freezing and expanding moisture in places where that moisture was not supposed to get into?

Not the most stupid post ever made Timmy.  very lateral. 

Suspect the the general lack of precip will be more welcome than any of the unexpected issues re freezing and expansion of saturated ground. 

[IDO]

17 minutes ago, johnholmes said:

I cannot see how you consider that GFS has been consistent. Take a look at how it has changed with its two main runs 00 and 12 on this site. You pick a date, I chose Sat 16th, and see how it changes?

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&CONT=euro&MODELL=gfs&MODELLTYP=1&VAR=prec&WMO=&ZOOM=0&RES=0&PERIOD=&PANEL=0&ARCHIV=0&BASE=201601100000%26HH%3D144

I think we are talking about when the cold uppers leave the UK. This has consistently been forecast by the GFS at around the same day or so.

If you were to compare who has been getting it wrong then all models have been all over the place, UKMO flip flopping, ECM going for locked in cold from the North to Easterly's to UK highs.

This is a very complex situation and I think most on here are more concerned how long the cold stays than whether precise mesoscale details have been pinpointed? Go to the bias charts here: http://www.wpc.ncep.noaa.gov/mdlbias/ and compare all the D6 bias for heights and all models are struggling! Compare the 5 day then to the 10 day stats and it is even clearer that lots of entropy at the moment as the 10 day stats are much better. We shall see the verification stats soon re the upcoming period, and expect all models to suck to one extent or another.

So it's more a case of consistency within the high entropy picture and GFS over the last 2-3 days has been consistent in a short cold snap, where as ECM keeps promising all sorts of blocked locked in cold. Who is right is the main question and until that is resolved we don't know if GFS is consistently right or consistently wrong (re cold snap longevity)?

[Chris1986]

End of Jan could be interesting.

[phil nw.]

Looking at the latest London Ens from both  00z suites

and we can see the dip in the 2mtr temps. for this week with the back end of the week looking the coldest after the lowest upper temperatures filter south.

Again the ens show that large split developing at the start of week 2.

Clearly GFS Op is keen to jump into a milder flow from the Atlantic into next week and to sink any high developing around the UK  from day 7/8,as shown on both ECM/GFS

ECM would at least prolong the cold at the surface with frosts even though the colder uppers are moved away east.

I can't finish without a mention of the UKMO output this morning.That is a nice chart at T144hrs as it re-amplies the Atlantic ridge into Greenland,re-envigorating the Arctic feed and likely increasing chances of a longer cold period.

 

We can certainly see why there is so much uncertainty into week 2 medium term when there are still differences in the next few days.

 

 

[snowice]

1 hour ago, nick sussex said:

Well reading some of the NCEP state discussions it seems that the UKMO has not gone completely mad this morning.

Although they don't refer to it specifically the actual expected pattern does lend support for the troughing to the west to sharpen up in response to more amplitude upstream.

They expect the pattern to flatten out temporarily before re-amplifying by next weekend with an eastern USA trough. The differences are really the degree of amplification and different handling of shortwaves running east between the respective outputs.

Well as you say if the ukmo hasn't gone completely mad it may be on to something, this evenings runs will be vital as we are entering the realibile time.

Lol I can here the voices what is FI,I just have a feeling there are more twists And turns to come in what has been a fantastic model watching week.I think tonight's outputs will be vital God help the poor contryfile forecaster on duty this evening! Just feel it's time us coldies  got a rub of the blue  not green lol.

 

[Eskimo]

Just now, Chris1986 said:

End of Jan could be interesting.

Unfortunately, any changes to the stratosphere take around 4-6 weeks to create an effect on the weather we see. That would take us to March. 

[lorenzo]

2 minutes ago, Chris1986 said:

End of Jan could be interesting.

Be careful with the 06z - it has a tendency to get excitable about the stratosphere, we have been here before with over-progressive warming projections..

 

4 minutes ago, IDO said:

I think we are talking about when the cold uppers leave the UK.

Am all for looking at mid-range IDO, but many am sure will be looking at the strength of the cold arriving first versus it's departure,no?

[Chris1986]

2 minutes ago, PerfectStorm said:

Unfortunately, any changes to the stratosphere take around 4-6 weeks to create an effect on the weather we see. That would take us to March. 

The next 4 weeks of model watching will be interesting, I look forward to see if the gfs continues to develop this feature!!

[johnholmes]

8 minutes ago, IDO said:

 

From the anomaly charts, not the GFS version, but NOAA and ECMWF, they both suggest that the 6-10 day outlook from now is for cold to be still over the UK. My own interpretation of these 500mb charts is that the cold will by then be largely a dry cold with both the upper ridge and a surface high beneath it governing the weather. How long post 10 days is open to doubt. Over many years the feeling is, and proven when working, that we try to shift cold air too quickly. The NOAA 8-14 suggests this may be starting in that time frame. Time will tell of course.

[bluearmy]

3 minutes ago, PerfectStorm said:

Unfortunately, any changes to the stratosphere take around 4-6 weeks to create an effect on the weather we see. That would take us to March. 

Depending upon the trop pattern and also how any SSW manifests itself re down welling we can see a quick trop response within a few days.  Irrespective of that,  I would say less than three weeks is usual for first downwelling wave to strike the trop. as others have said, an SSW can actually 'shake' the trop out of a cold pattern that is affecting us at the time any wave strikes the trop. 

we have a very strong strat vortex this winter and yet the trop is making pretty cold patterns. as big a disconnect as we've probably seen for a fair while. 

[IDO]

1 minute ago, lorenzo said:

Be careful with the 06z - it has a tendency to get excitable about the stratosphere, we have been here before with over-progressive warming projections..

 

Am all for looking at mid-range IDO, but many am sure will be looking at the strength of the cold arriving first versus it's departure,no?

Yes of course but I think we have agreement in the short term (up to D5), a cold spell is incoming that will feel bitter compared to the last 6 weeks of mild. Snow marginal but too early to be forecast with confidence, analysis 24 hours before may be the best here. So I had moved on to the longevity of the cold snap/spell and no strong consensus, I was just pointing out consistency. I have no preference or clue which way it will go, beyond my pay grade, just highlighting there is differences and we shouldn't all be swayed by those ECM D8-10 charts (at the moment).

[Chris1986]

6 minutes ago, lorenzo said:

Be careful with the 06z - it has a tendency to get excitable about the stratosphere, we have been here before with over-progressive warming projections..

 

Am all for looking at mid-range IDO, but many am sure will be looking at the strength of the cold arriving first versus it's departure,no?

Last few runs seem to be progressively bringing this in. I will watch the development over the next few weeks

[Chris1986]

8 minutes ago, bluearmy said:

Depending upon the trop pattern and also how any SSW manifests itself re down welling we can see a quick trop response within a few days.  Irrespective of that,  I would say less than three weeks is usual for first downwelling wave to strike the trop. as others have said, an SSW can actually 'shake' the trop out of a cold pattern that is affecting us at the time any wave strikes the trop. 

we have a very strong strat vortex this winter and yet the trop is making pretty cold patterns. as big a disconnect as we've probably seen for a fair while. 

I've got a nasty feeling this is why the various models have been so different going out to FI but I am certainly no expert. I can't find any strat charts for anything apart from GFS can anyone point me in the right direction? I'd like to do a comparison.

[Timmytour]

7 minutes ago, Chris1986 said:

End of Jan could be interesting.

Made me look at the run of that.....

How accurate are they?  Any more accurate than the SLA and 850 temps?  Is there an overall driver.

I notice that the 6z goes from this at T30



Build in the purpley pinks to T72

 

Then brings them out until by T120 they have disappeared

 

This seems to coincide with when the GFS run goes from a "oh could be..." one to a bit "it's all going meh"  .  would they be linked?

 

[johnholmes]

11 minutes ago, IDO said:

Yes of course but I think we have agreement in the short term (up to D5), a cold spell is incoming that will feel bitter compared to the last 6 weeks of mild. Snow marginal but too early to be forecast with confidence, analysis 24 hours before may be the best here. So I had moved on to the longevity of the cold snap/spell and no strong consensus, I was just pointing out consistency. I have no preference or clue which way it will go, beyond my pay grade, just highlighting there is differences and we shouldn't all be swayed by those ECM D8-10 charts (at the moment).

Nor should we be swayed by adherence to GFS outputs IDO. Check the 1, 3, 5 or 10 days 500mb statistics for the northern hemisphere and GFS is almost always behind UK met out to 120 and ECMWF to 240h and by increasing margins as one gets further from T=00.

A careful overall look at all outputs beyond about T+144h and looking, not for detail, but consistency in the upper air, not the surface. From experience it is hard enough to get the right pattern at 500mb but infinitely harder to get it at the surface, even without making it even more complex by the addition of moisture.

[Captain Shortwave]

Regarding model consistency, lets take the ECM day 10 from Friday morning.

Worth noting on this run we saw a deep low move through the south of the UK from the Azores, this of course has been settled into a shallow feature affecting France at a much earlier timeframe.

So what about the ECM yesterday at day 9

The correct modelling of the Azores low had be honed in on by now. Overall the longwave pattern looks quite similar, a ridge just west of the UK with a surface high right over the UK.

Today

Whilst the ridge is weaker and more susceptible undercutting, the actual longwave pattern is pretty similar. So at least for the 00z suite this has been a consistent trend beyond our cold snap, it actually extends this by creating a cold surface block over the UK as opposed to two days ago.

So the GFS

Friday (240h), Saturday (216h), Today (192h)

 

Again the chart on Friday can be forgiven as it also was struggling to model the Azores low consistently. Again the GFS from this point has gone for a milder solution though it is starting to drag that trough to our east further west and being shown to be a more significant feature which could prop up the high near the UK.

Take what you want from this, but the ECM has consistently gone for a deep trough over eastern Europe and in the western Atlantic at this point with high pressure over the UK. The GFS gone from a flatter and milder pattern, but with some signs of change. As for the 06z...

More significant trough to our east again. The ECM has been forecasting a deep freeze developing over East and south east Europe since yesterday morning. The GFS is trending towards this and gradually bringing further areas into the influence of that trough. If it does this again for the 12z then I would expect the high to be further north west and close to the UK at this time frame. One to watch.

I might do the 12z suites this evening to add a bit more to this, obviously after this afternoons output.

Edited January 10, 2016 by Captain Shortwave

[Weather Boy]

25 minutes ago, PerfectStorm said:

Unfortunately, any changes to the stratosphere take around 4-6 weeks to create an effect on the weather we see. That would take us to March. 

That's not correct. I said the same thing 2/3 years ago and Chio (who, for the benefit of newbies, definitely knows!) corrected me to say that it can have a more or less immediate effect on the troposphere. Alternatively it can take 2-3 weeks to cause changes in the trop. To say 4-6 weeks is pushing it I think but also wrongly dismisses the possibility of an immediate impact.

Of course that doesn't mean that it will have an impact, immediate or not, on our small part of the globe.

[Connor Bailey Degnan]

Here, i have attached the Precipitation, dew points, upper airs 850pha and precipitation type at 6am on 14/01/2016 and you can see just how incredibly difficult it is to predict. 

Edited January 10, 2016 by Connor Bailey Degnan

[Harsh Climate]

Looking at the gfs 06z in it's own right a very disapointing run, thankfully in it's essembles it's very much one of the more milder progressive members!

Regarding the essembles one thing to look out for in a possible milder breakdown from the west/south west. Any member that does not go above '0' 850hpa means the mild air hasn't won and at very least we would be under cold surface air with day time temperatures struggling to reach 1 or 2 degrees, So something to look out for.

 

UKMO is perfection 10/10 this morning

A return of the greenland high that many have already written off, no support but never the less nice to see.

 

ECM is middle ground territory this morning, not a bad run at all. 

144h really cold chance of the odd snow shower in places, no sign of an atlantic breakdown, good.

192-240 pretty bog standard but notice the siberian high build, for me an easterly would be on the cards if this run was to play out further, again no sign of atlantic breakdown.

.

 

All in all I would have the chances of a milder atlantic breakdown after next weekend sitting around 40% now. For me that has flipped from 60% to 40% overnight, we are certainly heading in the right direction! Rearding snow nothing has really changed, next week looks very messy but I certainly see snowfall's just quickly cropping up out of the blue and could be just about anywhere. Obviously a little elevation would be hugely beneficial in this set-up.  

Edited January 10, 2016 by Harsh Climate

[Severe Siberian icy blast]

47 minutes ago, PerfectStorm said:

Unfortunately, any changes to the stratosphere take around 4-6 weeks to create an effect on the weather we see. That would take us to March. 

I have no idea where you got that from . On average it's 21 days . Sometimes a little longer . Let's not forget we also can have an almost immediate response.  If the vortex is primed rightly it can happen within 5 days

[Midlands Ice Age]

38 minutes ago, Captain Shortwave said:

Regarding model consistency, lets take the ECM day 10 from Friday morning.

Worth noting on this run we saw a deep low move through the south of the UK from the Azores, this of course has been settled into a shallow feature affecting France at a much earlier timeframe.

So what about the ECM yesterday at day 9

The correct modelling of the Azores low had be honed in on by now. Overall the longwave pattern looks quite similar, a ridge just west of the UK with a surface high right over the UK.

Today

Whilst the ridge is weaker and more susceptible undercutting, the actual longwave pattern is pretty similar. So at least for the 00z suite this has been a consistent trend beyond our cold snap, it actually extends this by creating a cold surface block over the UK as opposed to two days ago.

So the GFS

Friday (240h), Saturday (216h), Today (192h)

 

Again the chart on Friday can be forgiven as it also was struggling to model the Azores low consistently. Again the GFS from this point has gone for a milder solution though it is starting to drag that trough to our east further west and being shown to be a more significant feature which could prop up the high near the UK.

Take what you want from this, but the ECM has consistently gone for a deep trough over eastern Europe and in the western Atlantic at this point with high pressure over the UK. The GFS gone from a flatter and milder pattern, but with some signs of change. As for the 06z...

More significant trough to our east again. The ECM has been forecasting a deep freeze developing over East and south east Europe since yesterday morning. The GFS is trending towards this and gradually bringing further areas into the influence of that trough. If it does this again for the 12z then I would expect the high to be further north west and close to the UK at this time frame. One to watch.

I might do the 12z suites this evening to add a bit more to this, obviously after this afternoons output.

https://nwf.nwstatic.co.uk/forum/uploads/monthly_2016_01/image.gif.4c30ab8de318c2f68a00da9fb111c3c7.gif

I am not sure that the GFS hasn't backtracked lads.

The above is the forecast for this week. Note the high pressure in the Eastern Atlantic.

Two or three days ago it was forecasting this --

 

 

 

The above was the start of my thoughts...

Captn has beaten me to it so I stopped.....

As you can see, from the GFS it has consistently modelled the heights to our south pointing towards Spain. (ie ne wards). It has made huge changes to the north, with no consistent longwave pattern.

As Capn points the longwave pattern over the Atlantic on the ECM has not changed, apart from the high instead of pointing north seems to be angled more towards the North west.

It is this that is effecting the timing of the return of milder air. To claim that the GFS is more consistent is incorrect.

 

Edited January 10, 2016 by Midlands Ice Age

[IDO]

 

It looks like the ECM has lots of entropy with respect to it's members and spread by D7 is amazing. This shows with the op being the coldest run at D9 in the De Bilt graphs:

Looking at it's members it does appear that many are dry but milder so I suspect a good cluster in line with the GEFS mean. Would not rule out anything from the ECM tonight with that spread!

[ukpaul]

ECM for London, in fact, is showing that the op is at the mild end for the key timeframes of the 14th-16thy, any spread at day seven being because of a few isolated members.

Would a chart for the US have an effect on the UK at the same time? Not as much as it would down the line.