Model Output Discussion - Early November Onwards

[trisnow]

hi and welcome to Net Weather.

Others have already described what happens on here especially during winter. Perhaps you might like to look at the Net Wx Guides section. In there are lots of explanations about all manner of things to do with understanding the models/weather etc. One on using the GFS output to try and forecast for your location. It needs very little understanding of the models. But to be honest I would spend time trying to learn, don't be afraid to ask questions, pm me if you wish.

Enjoy watching the weather.

oh, my old hobby horse! - could you stick your nearest town in your avatar so we all know where your reports of your weather are coming from please - thanks

Many thanks John. Will take a look and will add details now.

[shedhead]

If you are hoping for a cold winter look away now! http://www.cpc.ncep....s3/euT2mMon.gif

This time last year the CFS had north Europe under deep blue for December and light blue for January!

Expect the worst to avoid disappointment me thinks...

Karyo

I don't view them as the be all and end all, but I certainly take on board what they show and to be fair they have been pretty consistent of late - whether they ultimately prove to be accurate or not however, only time will tell. Once again tho the posting of them highlights just how fickle this forum can be, because I'm pretty certain that if they showed deep blue across the UK from now til March they'd be getting far more favourable and significantly greater coverage, as they did last Autumn.

[karyo]

Do you have shares in it? :smilz38:

It got the late winter and spring here completely wrong and I have very little faith in it. And given that this thread has been awash with doom and gloom recently maybe its best to not post that link in case it sends some people over the edge!!!

Lol!

I think it helps to keep expectations low and then hopefully one or two cold surprises may turn up!

[johnholmes]

Many thanks John. Will take a look and will add details now.

thanks for that-not too far away then, not far for you to travel when the famous height example of rain to snow in the Sheffield area occurs?

[Frosty.]

I don't view them as the be all and end all, but I certainly take on board what they show and to be fair they have been pretty consistent of late - whether they ultimately prove to be accurate or not however, only time will tell. Once again tho the posting of them highlights just how fickle this forum can be, because I'm pretty certain that if they showed deep blue across the UK from now til March they'd be getting far more favourable and significantly greater coverage, as they did last Autumn.

I'm hoping the ECM +32 DAY MODEL which we don't see, is still showing a change to cold by late nov/early dec or maybe that has gone pear shaped this morning, the ecm out to T+240 won't be showing anything cold for several more days at least.

[johnholmes]

I promised a more in depth look at what the 500mb anomaly charts have been shoing over the past few days, see the pdf below.

500mb charts etc on sun 6 nov 11.pdf

[karyo]

I don't view them as the be all and end all, but I certainly take on board what they show and to be fair they have been pretty consistent of late - whether they ultimately prove to be accurate or not however, only time will tell. Once again tho the posting of them highlights just how fickle this forum can be, because I'm pretty certain that if they showed deep blue across the UK from now til March they'd be getting far more favourable and significantly greater coverage, as they did last Autumn.

I couldn't agree more! If CFS was promising a cold winter or even a cold month, it would get more favourable comments here!

Karyo

[Frosty.]

Exacta weather is promising the coldest winter since last december but the models show no signs of that prediction coming true although at some point in the next 3 months, the 500 mb anomoly charts are bound to change..surely.

Edited November 6, 2011 by Polar_ Low

[thetonynator]

Exacta weather is promising the coldest winter since last december but the models show no signs of that prediction coming true although at some point in the next 3 months, the 500 mb anomoly charts are bound to change..surely.

Given that this is the first winter since last December is it not stating the obvious that it's going to be the coldest since then? It's also going to be the warmest, wettest, windiest, calmest and driest!

[shedhead]

I promised a more in depth look at what the 500mb anomaly charts have been shoing over the past few days, see the pdf below.

500mb charts etc on sun 6 nov 11.pdf

Thanks for that John. I agree that within a fortnight we might well be seeing a different 500mb pattern being progged, but by then we will already be into the last 3rd of the month and probably viewing any changes for early December. That of course is no bad thing, at least we may see some wintry weather as we offically enter it, but there's still a long way to go from here. As you say tho, 'tentative signs', which have to be better than the 'no signs' at all that we've witnessed for the last fortnight or so.

[BLAST FROM THE PAST]

if you look at the NH ens plots, you will see that the flow on our side of the NH is very amplified. assuming that continues, we have a shot at ending up in the right part of the amplification. agreed that for the foreseeable, we are in the warm sector of that blocking, but what happens as we enter the final third of november is open to question as upstream WAA could promote retrogression of the block. tenuous at the moment but much more likely to get something cold from an amplified pattern that a flat zonal one.

Indeed and well put. We have amplification, we don't have a huge PV just to our NW. This set up is apparently a 1-8 MJO phase which in winter is pro cold set up than in Nov. Will the MJO change? We won't be stuck in this particular pattern forever. The lack of bad position PV, the jet amplification and willingnes to send energy way south is all part of the good signs to increase chances of cold shots.

Re models not showing cold at mo is correct and is likely to be correct for next 2 weeks yet IMO ie mild to rule the roost. However there is very little likelihood of a flat jet PV to our NW scenario which is good. I am happy with and have been happy with the autumnal set up re jet behaviour etc thus far.

BFTP

[shedhead]

Exacta weather is promising the coldest winter since last december but the models show no signs of that prediction coming true although at some point in the next 3 months, the 500 mb anomoly charts are bound to change..surely.

I will not be judging Madden on his Nov forecast, I'll be judging him on how quickly and to what extent he admits that he got it wrong. Worryingly he updated (or rather re-stamped) his November forecast in late October, despite the fact it was pretty obvious that a pattern change to cold/very cold was a long, long way away at that point, so it will also be interesting to see if he updates Winter as a whole again before the end of this month.

[Frosty.]

Given that this is the first winter since last December is it not stating the obvious that it's going to be the coldest since then? It's also going to be the warmest, wettest, windiest, calmest and driest!

hmm I think you missed the point, last december was the coldest for many years but was then followed by a benign milder jan and a much milder feb. The current models are continuing to show this stubborn pattern repeating itself for the next few weeks at least and there are no building blocks to anything cold at the moment.

[Rocheydub]

hmm I think you missed the point, last december was the coldest for many years but was then followed by a benign milder jan and a much milder feb. The current models are continuing to show this stubborn pattern repeating itself for the next few weeks at least and there are no building blocks to anything cold at the moment.

I knew what you meant anyway!

Is there anyone on here with access to the long range ECM charts? Anything to report way out there?

[nick sussex]

I couldn't agree more! If CFS was promising a cold winter or even a cold month, it would get more favourable comments here!

Karyo

I think I've been pretty consistent regarding the CFC since we've had access to them, regardless of what they show I don't rate their reliability and thats my view across all LRF's.

Whilst we can look at background teleconnections to see what the atmosphere may be predisposed to offer in terms of colder or milder synoptics there are no guarantees either way.

I admire the time people put into their LRF's in here and of course only through people doing these and seeing perhaps where things may have gone wrong or right do we continue to learn and perhaps in the future get more accuracy with these however I will always stand by my assertion that we will never be able to accurately predict the weather months ahead.

[Frosty.]

I knew what you meant anyway! Is there anyone on here with access to the long range ECM charts? Anything to report way out there?

If you look back at yesterdays posts, you will see a post relating to the extended ecm but it could be old news by now.

[Rocheydub]

If you look back at yesterdays posts, you will see a post relating to the extended ecm but it could be old news by now.

Got it, thanks... Interesting. GFS up to mega FI (past 21st Nov) points to a sharp cool down again, with -5 uppers on the doorstep of my wee land with fairly low DAM line near also... Wouldn't take a lot to bring that over our 2 islands don't you think?

Yeah, I know it's way out in FI...

Edited November 6, 2011 by Rocheydub

[chionomaniac]

I promised a more in depth look at what the 500mb anomaly charts have been shoing over the past few days, see the pdf below.

500mb charts etc on sun 6 nov 11.pdf

One can see from those charts that even though the NAO is programmed to go negative, the position of the Atlantic trough is such that cold meridional transport does not arrive at our shores. When looking at the NAO forecasts it is worth point out that it is always worth aligning this to the NWP output available as well. Whereas generally we can say that a negative NAO is good for delivering cold to our shores, this is a particular time when it is not. Again, Fred (BFTP) has repeatedly mentioned the pattern that is set to deliver a more pronounced negative NAO to our shores and it could be a case of being so right and yet so wrong! ( that is the assumption that most have made - me included - that if we have a negative NAO it is game on!)

Edited November 6, 2011 by chionomaniac

[nick sussex]

Looking at the UKMO extended outlook that IMO is basically saying we don't know whats going to happen and have put together a non- descript outlook.

If you take the output as a whole together you could make a case for both a continuation of the current stalemate but also for some changes, at the moment I'd edge towards a change as the upstream pattern is unlikely to allow that high to sit there especially with high pressure towards eastern Canada.

Most likely IMO is pressure falling over Scandi, the high being squeezed westwards with that trough retrogressing, and some pressure rises to the nw.

[Frosty.]

I will not be judging Madden on his Nov forecast, I'll be judging him on how quickly and to what extent he admits that he got it wrong. Worryingly he updated (or rather re-stamped) his November forecast in late October, despite the fact it was pretty obvious that a pattern change to cold/very cold was a long, long way away at that point, so it will also be interesting to see if he updates Winter as a whole again before the end of this month.

LOL he posted a nice pic of a wet snow shower in ireland and a snowdrift near the summit of cairngorm to prove his point about moderate to heavy october snowfalls but he may struggle this month. The models are still hinting some sort of pattern change in around 2 weeks time but that could easily get shunted back as the current pattern may continue to renew itself for a while yet!

[rich1]

Some curious charts on show at the moment, very unusual really for the time of year with a lot of High pressure around

surface temperatures are likely to fall after mid month though I reckon, and it looks pretty dry for quite a few areas. This November could be a odd month, its usually a lot more disturbed than this

[BLAST FROM THE PAST]

One can see from those charts that even though the NAO is programmed to go negative, the position of the Atlantic trough is such that cold meridional transport does not arrive at our shores. When looking at the NAO forecasts it is worth point out that it is always worth aligning this to the NWP output available as well. Whereas generally we can say that a negative NAO is good for delivering cold to our shores, this is a particular time when it is not. Again, Fred (BFTP) has repeatedly mentioned the pattern that is set to deliver a more pronounced negative NAO to our shores and it could be a case of being so right and yet so wrong! ( that is the assumption that most have made - me included - that if we have a negative NAO it is game on!)

Hi C

Correct and I agree. I did mention when I made posts like that, that a -ve NAO will not promise cold to these shores as west based -ve NAO is so not good for us. It does however, enhance our chances and that a southerly jet will be another aid.

BFTP

[nick sussex]

The UKMO at 144hrs is the most interesting output for weeks but there are some big differences between it and the GFS regarding the amplitude of that upstream trough.

[phil nw.]

Hi C

Correct and I agree. I did mention when I made posts like that, that a -ve NAO will not promise cold to these shores as west based -ve NAO is so not good for us. It does however, enhance our chances and that a southerly jet will be another aid.

BFTP

Hi Guys,

I am puzzled re.your exchanges about an "existing" -NAO .

I have run through the 12z GFS and out to T240 i cannot see a -NAO pattern.

I do see a lot of energy still north of 60degrees coming off the Eastern seaboard with quite a lot of mid-latitude high pressure in the Atlantic so i cannot see this -NAO, west based or otherwise.

Here at T144 is typical of this run

Certainly what we do have is "warm" euro high persisting for a while yet and a weakening atlantic trough keeping us in a mild southerly type flow.

Forgive me if i have missed something in which case i am sure you can enlighten me,

Regards,Phil

[I remember Atlantic 252]

A fantasy chart ensemble no 7, deepest FI, but 0perational seems more realistic