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Model Output Discussion 18th Nov.2013-12z onwards.


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I suppose there's no reason today to regard what the models are giving us for a week's time with any more conviction than, in hindsight, we could regard what they were telling us at the weekend for this coming weekend and beyond. The science has come a long way, but there's still no way of capturing every little element that can produce a substantial impact within the programming.

I'm optimistic about an eventual prolonged spell. My feeling over the last few winters is that the models seem to press and probe at it when certain signals arrive and while those signals don't always deliver, in the end the pressure of them mounts up and we get there.

Just a gut feel, but i think it likely that things will get colder (properly so!) around the 16th December and the first clear signs of this will arrive in the models in the first week of December

Edited by Timmytour
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My broad brush statement regarding the upcoming weather in the UK, at least from my locale would be as follows.

 

Some short-term excitement throughout today and tomorrow for those like convective showery type airmasses. Some wintriness more exclusively at elevation.

 

From Friday 22nd November through to Tuesday 26th November at least, we will be under the influence of High Pressure, so it will be largely dry, if rather cloudy at times. As and when the cloud clears by night it will obviously set up the chances of rather harsh Frosts.

 

From Wednesday 27th November (a week from today) there is the possibility of the Atlantic breaking things down from the North. IMHO, it is most likely the first breakdown whenever that may be, will arrive initially from a cold Northwesterly flow. Read the Snow and Ice thread for more info as to how cold things are becoming around Iceland and Greenland in terms of sea-ice. Posted Image

 

Any FI charts will be lurking somewhere between t+120 and t+144 hours and BEYOND based on current projections. Any charts after this timescale, which intriguingly fits in with my comments above should be taken with a GRITTER load of salt, excepting any trends that might be determined over multiple runs and over multiple outputs.

 

I hope that helps assist anyone who simply dips into this thread from time to time and may or may not be confused by the wider Northern Hemisphere picture. Posted Image

Edited by gottolovethisweather
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I think the chances of something popping up unexpectedly are pretty much dead now as no energy is modelled to get under our block around the mid range now, pretty much consensus on a settled spell of weather for the UK then and most people will be tuning in to FI to look for the next opportunity for some HLB.

 

Some folk seem to want to write off such prospects for weeks which is a little silly but it is fair to say we can almost certainly write off the rest of November but...

 

There is a pattern change likely to take shape in around 10 to 14 days and currently the only real signal in among the noise is for pressure to drop over the UK and hopefully Europe with the Azores high being displaced West which if the troughing is strong enough could signal another mid Atlantic ridge and some WAA toward Greenland which would be our next shot.

It is just a case of wait and see but GFS ensembles did pick out the initial Atlantic ridge and the signal is similar again though of course there is a long long way to go before we can call anything (we are talking early part of Dec for developments here and even then the pattern change may something much flatter not more amplified)

 

Anyway I aid much the same last night so I won't keep banging on about it, it is just something to hold the interest while we go through this decent yet synoptically rather uninspiring period weather. In this regard I make no apologies for posting the deepest FI charts as an illustration of what I hope to see develop as a signal)

 

Deep trough and Azores high being displaced West. (GFS 06z Op)

 

Posted ImagePosted Image

 

GFS 00z Op much weaker signal, same theme results in a toppler

 

Posted Image

 

 

Hope that doesn't annoy some folk as these are not cherry picked charts, there are much better among the ensembles. They simply illustrate that currently the strongest signal in FI is for a pattern change early December and what shape that may take. It may also help beginners understand  a classic winter method of building blocking as a precursor to pulling in cold Arctic air to the UK from N/NE/E.

 

Edit insert: I should just mention that this signal will come and go in the Operational runs, it is more important to look through the ensembles to see how things are progressing.

 

Of course all the usual caveats apply at such a long range and it will also be worth keeping an eye on the pressure anomaly charts updates for December as well pertinent information from the likes of Ian Ferguson and the MetO.

Edited by Mucka
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It may not have been strictly zonal CH, but it became unsettled long before 26th Oct. Here is the 00 Exeter analysis from the 17th (1 month prior) and you can go back even further into Oct

to find very similar charts...

Posted Image

Here's the 14th for instance.....

 

Posted Image

So a month and more of strictly zonal no, but definately a month or more of unsettled/changeable and mild...not sure most who were under all the rain would be to pedantic about where it came from. 

Edited by Paul
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The track of Melissa is still evolving, but on this chart, only one model takes it northwards to a significant degree and some send it southeastwards, therefore underneath the high, I assume

Posted Image

 

Which exactly where we want it to go

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The Arctic blast shown at the end of the Gfs 06z op run has some support from the GEFS 06z perturbations, so it's not just some plucked out of the air fluke, therefore, the 6z mean is also showing a colder looking pattern during early December, hopefully a wintry blast will be brewing early next month.

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Posted · Hidden by Osbourne One-Nil, November 20, 2013 - But it's the model discussion thread, and he's discussing the models, so drop the crusade and stay on topic please.
Hidden by Osbourne One-Nil, November 20, 2013 - But it's the model discussion thread, and he's discussing the models, so drop the crusade and stay on topic please.

At that kind of range Frosty even 100% support would mean very little.  So much water needs to pass under the bridge before we can even hope to get a handle on the 6th Dec's weather and I suspect come this evening the 12z perts will be very different.

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Hi all,

been following this forum for many years and followed the highs and lows with you all. so I thought it's about time I joined lol.

So first of all id like to thank you all for some fantastic reading,

So on to the current models , as above^ catacol-highlander said it started on 26th and we had some great winter charts.! Then the models changed course it's far from game over and not even winter yet. Have faith things will change, our winter weather is a lot different now than it was 5yrs + ago. anything from 120hrs + can and often does change very quick in the winter months?Let's see what the 12z's have to say.

This is only the start plenty more ups and down to come..

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It may not have been strictly zonal CH, but it became unsettled long before 26th Oct. Here is the 00 Exeter analysis from the 17th (1 month prior) and you can go back even further into Oct

to find very similar charts...

Posted Image

Here's the 14th for instance.....

 

Posted Image

So a month and more of strictly zonal no, but definately a month or more of unsettled/changeable and mild...not sure most who were under all the rain would be to pedantic about where it came from. 

 

Would also be nice if someone could simply make a statement, whether factually correct or not, without it being labelled 'provocative' or similar.Posted Image

 

Well... perhaps I agree on the labelling point. My previous post somehow has been turned into gibberish but a couple of pointers: this was the situation on 17th Oct, and it was a million miles away from being zonal.

 

Posted Image

 

and if we are going to discuss the models and the reasons for our weather type I have to disagree with you - unsettled weather can come from a range of different synoptics, but the zonal call made by IB is one of low pressure to the north and high pressure to the south... and that hasnt been the case for a month. I posted yesterday that weather is grey and not black or white. That is a subjective interpretation of forecasting... but when it comes to an analysis of historical trend or past data then it is very definitely black and white. If its a daisy call it a daisy... but it would be wrong to call it a daffodil. Your 2 fax charts have high pressure over Greenland - they are also not zonal.

 

Was I unfair in using the word provocative? Perhaps. The trouble with Ian is that there is a very clear sense that he understands the weather very well. He is not a weather novice and no less knowledgeable than I - but too often I think we get comments that are designed to cause frothing at the mouth from those who dont fully understand the models and what is going on. That breeds confusion and upset. Those that know the weather tend just to ignore him when he makes such statements - but for those that are still learning or are craving for cold such comments are unnecessarily provocative. On that basis I think I'll stand by my judgement.

Edited by Catacol_Highlander
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Back to the charts - if there is anyone wondering why I am getting scratchy over the use of the word "zonal" here is a true zonal chart from GFS this morning for 1 Dec.

 

Posted Image

 

Horrendous chart if it is cold that you are after and a difficult pattern to break once it is established. Fortunately it is a long way out - and my own interpretaation of the upstream pattern is that we will have continued amplification. I posted this 100hPa chart showing a very wobbly pattern at 192 earlier, but it got trashed somehow. Here is is again.

 

Posted Image

 

 

 

So coldies do not despair.... though no signs yet of a significant cold spell.

Edited by Catacol_Highlander
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The track of Melissa is still evolving, but on this chart, only one model takes it northwards to a significant degree and some send it southeastwards, therefore underneath the high, I assume

Posted Image

 

 

The NHC seem pretty confident on the track now, and it's a big change for the inital track that was taking it north. She has also transitioned from subtropical to tropcial. I'm not really sure how much of an impact the system will have overall, but I suppose it's one less piece of energy that will be going up over the high.

 

Posted Image

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The Arctic blast shown at the end of the Gfs 06z op run has some support from the GEFS 06z perturbations, so it's not just some plucked out of the air fluke, therefore, the 6z mean is also showing a colder looking pattern during early December, hopefully a wintry blast will be brewing early next month.

 

Indeed Frosty, potential for a colder NW to SE flow (polar), yes zonal by nature but not the same type of dreaded zonal like those of the era which wouldn't dare be mentioned by a coldie such as myself. Posted Image My non rose-tinted spectacles do show nothing particularly inspiring in terms of prolonged cold right now at any range in the various outputs, pretty much as described by a few in the Stratosphere thread from earlier today. Posted Image  Some showers, then dry and hopefully crisp and sunny (far from certain) for most and then by this time next week, a whole range of options possible, but again I suspect some alteration from the then well-established drier spell. Posted Image

Edited by gottolovethisweather
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The track of Melissa is still evolving, but on this chart, only one model takes it northwards to a significant degree and some send it southeastwards, therefore underneath the high, I assume

Posted Image

hopefully that props up the high and we get a cold easterly developing.the models recently have taken it north and over iceland but now it looks like its heading straight for spain instead so does that mean there will probably be drastic changes in the output this evening? Edited by shaky
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I haven't seen anything that spells doom and gloom in the GFS up to t.144.  Yes it looks like HP is the order of the day come thur/fri and it looks set to remain in place. But temperatures will still struggle with some sub zero 850's remaining over much of the country. 

The HP also has a favorable tilt to it.  We may find that it retreats Eastward somewhat the closer we get to the weekend and the models firm up on what's going to happen in the 24/48 hr time frame.

 

Overall, I'm optimistic that as we progress towards this weekend, we may yet get some pleasant surprises in the outputs.  I certainly wouldn't be concerned with models showing anything Zonal past t.144. In fact the 06Z shows some very pleasant days ahead for the next week or two. A few warmer days early next week but colder 850's soon move back in. 

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hopefully that props up the high and we get a cold easterly developing.the models recently have taken it north and over iceland but now it looks like its heading straight for spain instead so does that mean there will probably be drastic changes in the output this evening?

Probably not, the only way would be for the tropical storm to drag the low coming off Newfoundland with it, that looks very unlikely as the main low is taken north when it engages the polar jet.

Looking at the GFS ensembles, the main objective is to see how cold the European mainland can get, by day 7 there is about as much divergence as you can get, some perturbations have Eastern Europe fully in the freezer whilst others show mild temperatures with all things in between. Worth noting there isn't much variance in this part of the world. 

Edited by Captain shortwave
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Maybe stating the obvious but if the last 7 days as shown nothing it has shown the variability of our climate over the uk ie how things have quickly changed in the mo.On that basis the next 7 days may move to and fro showing different scenarios because its a certainty whats shown at 144 hrs now will not be there in the mo come that date!!!Posted Image

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It was a bit little late last night but heres my post from last night if anyone missed it, the GFS 06z shows the continuation of the ridge in FI:

Posted Image

 

The ensemble for the 06Z shows a slight ridge at 360hrs:

Posted Image

 

It will be interesting to see what the 12z shows as the past 3 runs has shown this (with today's runs showing a better ridge)....

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The LP over the Canaries is much deepr and compact on the 12z and the High to our west is lower pressure so maybe the whole will shift N?

Posted Image

This chart has UK high written all over it for a long period, there is nowhere for the high to go until pressure rises in Europe at which point it will sink.
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