Model Output Discussion - The Start Of Winter

[ukpaul]

.....and the biggest warming yet suggested.

 

[Mucka]

Further to the post above pointing out GFS shortcomings expect to see it make the same mistakes re upstream pattern being too fast and less amplified than likely.

Remember how GFS refused to have a closed low and was ejecting energy East into the trough thus no ridge and a flatter pattern with no Northerly?

 

 

Well check today's GFS/UKMO 144 comparisons below.

 

 

That looks like it may be making the same error all over again and UKMO could well go on to give another Northerly outbreak with a separation of energy to our West and low pressure sliding Southeast so today's GFS 12z chart with the Azores high playing spoiler and ridging in may well be more amplified come the time with the Azores high squeezed West. 

 

 

We shall see but someone should tell GFS, those who ignore history are doomed to repeat it.  

PS

(in fairness) I should say it has some support for a flatter pattern developing from other models today 

Edited December 7, 2014 by Mucka

[knocker]

Hi knocker, what exactly does this mean for the Uk? Sorry I dont understand the jargon. Thanks GSL

 

Hi GSL

Well to me it says trough Greenland, west into NE Canada and east into eastern Europe with Ridge Alaska, which is also appearing on some of the later EPS signals. HP lying south into central Europe with no NE blocking.

 

So basically what the expert opinions have been suggesting that the UK remains in this unsettled westerly flow with rapid short term variations in the weather as systems pass either through or to the north.

 

Others of course may have a different interpretation.

Edited December 7, 2014 by knocker

[Hocus Pocus]

Hi GSL

Well to me it says trough Greenland, west into NE Canada and east into eastern Europe with Ridge Alaska, which is also appearing on some of the later EPS signals. HP lying south into central Europe with no NE blocking.

 

So basically what the expert opinions have been suggesting that the UK remains in this unsettled westerly flow with rapid short term variations in the weather as systems pass either through or to the north.

 

Others of course may have a different interpretation.

For the next 7-10 days possibly but as Ian F alluded to great uncertainty remains past this.

[knocker]

For the next 7-10 days possibly but as Ian F alluded to great uncertainty remains past this.

 

In case this is difficult to understand I posted this as I thought it may be of interest, Michael Ventrice obviously thought the same which is good enough for me. I was not, repeat not, attempting to make a point or a definitive statement. If it's causing a problem I can easily delete it.

 

Oh and feel free to correct my interpretation. Rest assured I won't be offended.

Edited December 7, 2014 by knocker

[Hocus Pocus]

In case this is difficult to understand I posted this as I thought it may be of interest, Michael Ventrice obviously thought the same which is good enough for me. I was not, repeat not, attempting to make a point or a definitive statement. If it's causing a problem I can easily delete it.

 

Oh and feel free to correct my interpretation. Rest assured I won't be offended.

No need to correct you as I was highlighting what the pros over this side of the Atlantic were referring to and trying to add some much needed balance as there is a great deal of uncertainty in the outlook at the moment and all options are possible.

[Polar Maritime]

A few posts have been moved to the ramp/banter thread.. Back to 'Model Output Discussion' please.

Edited December 7, 2014 by Polar Maritime

[IDO]

For the next 7-10 days possibly but as Ian F alluded to great uncertainty remains past this.

That is a 30 day anomaly chart from today's current ENSO and MJO. So I would assume that is a medium term composite, for the foreseeable. It pretty much reflects the GFS FI for the next 16 days, though as you would expect the signal weakens at the end of the GFS op run. Of course this is assuming that these two background forces are the drivers for the current NH weather, and I think that they are likely to be. So to override this likely output we need a stronger trigger and I suspect we will have to wait for the SSW, that will hopefully arrive in 3-4 weeks time.

Apart from a brief cold spell for the North next week the output is very uninspiring. GEM is still trying to bring us a mild spell from D8.

Edited December 7, 2014 by i'm dreaming of...

[knocker]

No need to correct you as I was highlighting what the pros over this side of the Atlantic were referring to and trying to add some much needed balance as there is a great deal of uncertainty in the outlook at the moment and all options are possible.

 

I'm intrigued as to why you feel much needed balance is required. I would have thought the one common denominator is the agreement on long term uncertainty with perhaps a leaning towards towards no foreseen major changes in the next 14 day period.

[Hocus Pocus]

That is a 30 day anomaly chart from today's current ENSO and MJO. So I would assume that is a medium term composite, for the foreseeable. It pretty much reflects the GFS FI for the next 16 days, though as you would expect the signal weakens at the end of the GFS op run. Of course this is assuming that these two background forces are the drivers for the current NH weather, and I think that they are likely to be. So to overrun this likely output we need a stronger trigger and I suspect we will have to wait for the SSW, that will hopefully arrive in 3-4 weeks time.

Apart from a brief cold spell for the North next week the output is very uninspiring. GEM is still trying to bring us a mild spell from D8.

I'm not disputing what they are showing but merely highlighting that the MeO don't see it as clear cut, now if some think it is then good luck maybe your all in the wrong profession. This isn't a dig at yourself or anyone in particular really.

[ukpaul]

Short ensembles picking up on the potency of this week's snow - this for Glasgow (ish).

 

[Zenarcher]

Some interesting weather ahead for next week in parts of the country,

 

Monday Looks to be a fairly nice day across the UK mostly sunny, dry and bright. There will be a cold North Westerly strong breeze that could touch gale force at times in the North. During the evening minimum temperatures look to get down to around -6c in the North and around 0c to 3c elsewhere. Frost and ice will develop in most places. The Met Office issued a watch for this.

 

 

Tuesday it's good to see the models eventually got the hang of the deep low that's due to form on Monday evening to the South East of Greenland, earlier predictions had it track straight to the UK so it looks liked we dodged a bullet with this one.

 

 

For the UK it's looking like a wet and windy day with rain being widespread for most of the day turning to showers in the evening which may be wintry over Scotland and Northern England. Gusts up to 70mph are likely in the North West of Scotland and all of the UK will have windy weather with gusts ranging from 35 to 50mph. Tuesday morning will start off very cold with a chance of some frost but temperatures are expected to rise as the day goes on.

 

Wind Gusts

 

 

Snow Risk on Tuesday Night

 

 

Wednesday The deep area of low pressure has moved away from Greenland and now sits to the far North of Scotland although it has weakened in strength it will still bring a unsettled spell of weather with it.

 

 

The South East of England looks clear and sunny for most of the day. Elsewhere is expected to be cloudy with wintry showers mainly being in the North West,

 

Snow Forecast for Wednesday Day Time

 

 

Wednesday Night Time

 

 

The main concern is the strong Westerly wind speeds where gusts could reach 70mph in some places and the Met Office also have a watch issued for this. Gusts will be mostly around 40 to 55mph slightly more than Tuesday's strong winds.

 

 

Thursday The deep area of low pressure continues to dominate our weather its looking like another cloudy and wet day for many with wintry weather continuing in the North West,

 

 

Snow Forecast for Thursday

 

 

Strong gusty winds for the Southern half mostly reaching 40 to 50mph but coastal parts could see 60mph.

 

 

During the night cold temperatures start to return thanks to the wind changing to a North Westerly direction,

 

 

Although still a few days away yet the current forecast does have some snow falling in then North West again during the night,

 

 

And by Friday morning there's a chance of it reaching the Southern parts of the UK,

 

 

Friday Still a fair bit away yet but its looking like there will be partly cloudy conditions along with showers inbetween and these showers could be wintry anywhere. A strong Northerly wind keeps the temperatures on the cold side.

 

On a side note something to watch the ECM 0z this morning did show a rather nasty low pressure system cross over Scotland bringing some high wind speeds,

 

 

Although this hasn't appeared on any of the 12z runs it does show that Scotland could be hit with a lot of snow if this did happen,

 

Edited December 7, 2014 by weathermaster

[Hocus Pocus]

I'm intrigued as to why you feel much needed balance is required. I would have thought the one common denominator is the agreement on long term uncertainty with perhaps a leaning towards towards no foreseen major changes in the next 14 day period.

Maybe I didn't make myself clear but here goes, if the MetO suggest there is great uncertainty past the 7-10 day mark then maybe we should take heed in what they say, now by great uncertainty I'm not suggesting there is a deep cold spell hiding somewhere just that there remains uncertainty in the outlook. For further information I suggest you ask one of the pros and not some amateur like myself.

[IDO]

I'm not disputing what they are showing but merely highlighting that the MeO don't see it as clear cut, now if some think it is then good luck maybe your all in the wrong profession. This isn't a dig at yourself or anyone in particular really.

If you reread the afternoon's posts you will see IF elaborate on the uncertainty. It is more to do it the potential for snow at the weekend and wind later this week than any looming pattern changes.

[Mucka]

A little more detail on the possible evolution of the pattern post day 5 and the upstream pattern using GFS ensembles for illustration.

 

As pointed out Earlier UKMO 12z does not phase the low pressure moving South (West of Greenland) with the weak trough over Canada around day 5 whereas GFS does.

Unfortunately we only get UKMO out to day 6 so I will use GFS ensembles to show how this affects the pattern later.

 

The following show the the phasing day 5 and the following pattern day 7. (2 frames each run)

 

 

 

Obviously there will be variation but the general theme is obvious, a flatter pattern with a less cold flow develops as the phasing of the trough allows the Azores high to ridge in.

 

Now an example of where the energy to our NE is kept separate.

 

 

As we would expect we get a more sharply defined trough and more amplified pattern though it is not the best example of how UKMO would be better than GFS going forward as it still can't resist phasing the energy in the same region a little later whereas UKMO would almost certainly continue to keep it separate by this stage.

 

 

Of course that only results in a more amplified colder zonal theme within the 10 day period so it is really detail rather than any major synoptic shift but it is also reasonable to suggest a more amplified pattern offers better opportunities of any future blocking setting up.

 

 

At least it is something we can watch develop as it should be resolved fairly soon one way or another.

I hope for ECM to be more in line with UKMO than GEM or GFS come day 5+

Edited December 7, 2014 by Mucka

[Polar Maritime]

I'm not disputing what they are showing but merely highlighting that the MeO don't see it as clear cut, now if some think it is then good luck maybe your all in the wrong profession. This isn't a dig at yourself or anyone in particular really.

 

Ok....... Back to what the Models are showing please. Any more off topic posts reg the Meto or anything other than, Will be deleted.

 

PM.

[johnholmes]

Hi knocker, what exactly does this mean for the Uk? Sorry I dont understand the jargon. Thanks GSL

 

quite right to question

We all tend to assume that everyone understands the abbreviations. I have lost count of asking for them to be explained or at least links to them for those not used to the terms. If you look in the Net Wx Guides they are in there, well most of them-hope that helps?

[Captain Shortwave]

Maybe I didn't make myself clear but here goes, if the MetO suggest there is great uncertainty past the 7-10 day mark then maybe we should take heed in what they say, now by great uncertainty I'm not suggesting there is a deep cold spell hiding somewhere just that there remains uncertainty in the outlook. For further information I suggest you ask one of the pros and not some amateur like myself.

After browsing the thread, it seems to be more down to uncertainties regarding surface conditions rather than the dominating longwave pattern. Pretty much the risk of damaging winds and potentially how cold the following cold incursion will be for next weekend. The general pattern still seems to favour a westerly pattern with transient cold/milder spells with temperatures near normal. 

GFS extended ensembles have low pressure to hold on to our north with a generally westerly flow, though again enough scope for winds to veer northerly at times. That said the difference between the 12z and 6z ensemble suites seem stark. Of course as Mucka shows, that cut off low could change things rather dramatically of course.

Edited December 7, 2014 by Captain shortwave

[ukpaul]

To illustrate that lack of certainty -

 

Control by end of run -

 

 

 

Op by end of run -

 

[Duane S.]

Interesting control run at the end, troughing 500 miles off th SW tip of Greenland likely to aid amplification in all the right places and help lower heights into Europe

 

 

More of that in the coming days/week please

Edited December 7, 2014 by s4lancia

[Summer Sun]

The north could see some snow even at lower levels on Thursday evening its going to depend on how quickly / slowly the low clears

 

 

Maybe some sleet and snow further south for a time during Friday

 

 

Western parts of Scotland could be hit by Blizzards for a time during the coming week then the end of the week is more uncertain but we need to keep an eye out for some widespread snow in the north

 

Bar a spell of higher temps on Tuesday with temperatures for most around 8c to 12c east Anglia is likely to see the lowest temps around 5c, then from Wednesday the risk of snow begins to increase again

 

 

[Mucka]

To illustrate that lack of certainty -

 

Control by end of run -

 

 

Op by end of run -

 

 

 

Yes and there has been a subtle shift within GFS ensembles for the pattern in FI to become more amplified. That is encouraging because GFS ensemble FI will normally flatten rather than amplify unless it sniffs something and though it is not good with detail I have seen it sniff out the first signs MLB/HLB setting up in deep FI on many occasions. 

Edited December 7, 2014 by Mucka

[Jason M]

Just looking through the GEFS in deep FI, and a few different options starting to appear including a few HLBs. I'm very wary of Greenland highs on GFS FI as I think at long distance GFS charts / ensembles tend to over play this option. That said, the fact that the long wave pattern is essentially zonal for the next ten days, it's interesting that a lot of the ensembles are breaking with the pattern deep in FI.

Only a subtle signal and maybe gone by 18z but something slightly different anyway.

[nick sussex]

Given the outputs so far this evening theres no backing for the ECM 00hrs run which was very progressive, seeing as these outputs have 12hrs worth of newer data I would be shocked if the ECM 12hrs didn't backtrack.

 

The end result might still be underwhelming at T240hrs but in terms of the possible northerly next weekend perhaps it might at least be less progressive with the low heights piling east and se.

[Duane S.]

Just looking through the GEFS in deep FI, and a few different options starting to appear including a few HLBs. I'm very wary of Greenland highs on GFS FI as I think at long distance GFS charts / ensembles tend to over play this option. That said, the fact that the long wave pattern is essentially zonal for the next ten days, it's interesting that a lot of the ensembles are breaking with the pattern deep in FI.

Only a subtle signal and maybe gone by 18z but something slightly different anyway.

Yep, tail end of GEFS is sniffing something out for sure. Lots of wild and wonderful versions of increased wave activity being played out. Like you say, is it the start of a trend or a blip?!

Edited December 7, 2014 by s4lancia