Model Output Discussion 29th December - Into mid-Winter.

[bluearmy]

8 minutes ago, chris55 said:

This is interesting Nick.

If the means/anomalies struggle with such synoptics/details, that ultimately have a profound effect on the outcome then how do we have confidence in the means/anomalies? And how do we read them with confidence?

I guess its a case of "best available tool" but not flawless by any means.

do you have a better method?

this is why, even if we do have cross model agreement at day 6, we still have to look for potential spoilers down to day 4. 

The ens/anomolies give a background and the ops generally show the potential detail within that background. 

[smogonthetyne]

Which model first predicted snow in Middlesbrough on NYD, and how far out. 

 

Its just verified

[Summer Sun]

 

[chris55]

5 minutes ago, bluearmy said:

do you have a better method?

this is why, even if we do have cross model agreement at day 6, we still have to look for potential spoilers down to day 4. 

The ens/anomolies give a background and the ops generally show the potential detail within that background. 

No I don't.

It just highlights how difficult it can be to get mid to long range weather forecasting right.

[chris55]

6 minutes ago, Summer Sun said:

 

How can you have a middle half??

[Seasonality]

7 minutes ago, Summer Sun said:

 

Middle half?

[bobbydog]

Just now, chris55 said:

How can you have a middle half??

I thought that! Divide it into quarters and use the middle two?...

Maybe referring to this- 

[John Cox]

1 minute ago, Larger than average Hobo said:

First Qtr, Middle Half, Last Qtr ??

2nd and 3rd week is my middle half of January 

[knocker]

Just now, chris55 said:

No I don't.

It just highlights how difficult it can be to get mid to long range weather forecasting right.

And further to ba's reply if one looked closely they didn't actually miss it. A brief look at random shows the LP pressure area in question and I think I mentioned on a couple of occasions the importance of this area, and how it wasn't cut off, when it came to the detailed evolution.

[bluearmy]

7 minutes ago, knocker said:

And further to ba's reply if one looked closely they didn't actually miss it. A brief look at random shows the LP pressure area in question and I think I mentioned on a couple of occasions the importance of this area, and how it wasn't cut off, when it came to the detailed evolution.

Indeed you did knocks though imagining the returning jet would force the low nw against the predicted southern split flow was a punt no one took 

[Catacol]

3 hours ago, Quicksilver1989 said:

Unfortunate to see another cold spell consigned to the bin. I think we can safely say that now.

I think there was a number of warning signs:

The sinking of high pressure to the south of the UK which really was a big blow, a northerly at the end of this week would have been a big help

Good agreement on the operational runs - Yes we should also look at the ensembles but we saw good agreement between the operational runs yesterday afternoon. The operational runs use a higher resolution then the accompanied ensemble members. The fact that three different models (UKMO,GFS and ECM) were showing stubborn heights to our SSE was a big warning sign, despite cold ensemble members still being shown. Most of these ensemble members saw the -10C isotherm barely clip the East Coast anyway.

Cold in Greenland and NE Canada - Pretty simple but with cold in these regions the Atlantic is always at risk of firing up. The low to the West of Iceland now goes against us given we don't have a northerly. The result is a flatter ridge to Scandi that doesn't get anywhere.

As for why this pattern keeps repeating... I don't think it's the westerly QBO as December 2010 was westerly. I did post this on NW a while back which is worth repeating for those who missed it and I stick by this interpretation:

Over the past few years we have had references to the North Atlantic cold blob, that has persisted. Some people say its gone but I think its still there. There is something in oceanography called the re-emergence mechanism. Basically in the winter the mixing layer (area that interacts with the atmosphere) is at its deepest due to the stormy weather. In the Summer months the mixing layer shoals. However the cold SSTs from the previous winter remain at depth, only to re-emerge again when it becomes stormier. Here is an example. First is March 2015, then December 2015.

 - March 2015

 

 - December 2015

See? the same SST pattern re-emerges again the following winter. It is interesting to note that this SST pattern is associated with increased cold air outbreaks filtering through the North Atlantic from NE Canada.

Unfortunately, here is March 2016....

 - March 2016

I get the feeling that unless some great atmospheric forcing overwhelms this then we will continue to see more westerly atmospheric circulation patterns then normal. I hope I'm wrong but in 2010 we had the opposite:

 - March 2010

 - December 2010

In 2013 we got bailed out by a good SSW event and I think we will need the same again. An SSW isn't a guarantee of cold but it increases the chances.

Now don't get me wrong I think this could easily turn around. Numerous ensemble members show northerlies for example. This however is well into FI.. I hope that the effects of low solar activity will kick in soon, like they did in 2008.

However for the reasons listed above, I am keeping my expectations very low. I am usually a cold ramper but this winter the background signals are favouring mild and this is what we have seen.

Good post. Atlantic Ocean temperatures havent been discussed much this winter - it is a subject that confuses me a bit I must confess as there seem to be contradictory conclusions on the impact of cold or warm water in the atlantic and whether it encourages or discourages cyclogenisis. I might go and read the Cold Atlantic thread again to brush up a bit.... but perhaps you are right in your analysis here. Not good for UK winters if so as my understanding of the billions of tons of ice being lost from Greenland each year makes the chances of cold ocean anomalies (perhaps accelerated by AMOC decline) more likely. It would be ironic if a cooling ocean acually reduced our winter cold through harder chances for polar continental air...

Edited January 1, 2017 by Catacol

[Summer Sun]

 

[snowwonder]

Not a great reader of the charts etc but have followed this discussion thread for a long time. Thank you all. Just looking at the model flip in the last 48hrs do you think it could flip back again as quick? Not sure I have seen such a quick change. But have learnt that no chart is worth getting excited about until it's <96hrs. Interesting all the same though. Happy new year 

[Scandinavian High.]

Is there any way we can still get the north easterly later next week or as the signal gone now for this and we look north west now thanks.

Edited January 1, 2017 by abbie123

[chris55]

6 minutes ago, abbie123 said:

Is there any way we can still get the north easterly later next week or as the signal gone now for this and we look north west now thanks.

Well it seems the MET put it at 20% so unlikely but not impossible.

[Ventnor Viking]

I know this is a bit off topic, but it's currently snowing in Shaftesbury North Dorset. I think this just proves that we look so far into FI chasing charts we don't look at all the little changes and things happening alot closer to the time 

[radiohead]

The GFS(P) is back...with a bang.

[booferking]

5 minutes ago, radiohead said:

The GFS(P) is back...with a bang.

When you said back with a bang i thought a flip to a cold NE wind for this weekend then i looked at the date on the charts.

Edited January 1, 2017 by booferking

[karyo]

4 minutes ago, radiohead said:

The GFS(P) is back...with a bang.

At this range it is only for entertainment value.

[radiohead]

4 minutes ago, karyo said:

At this range it is only for entertainment value.

Of course!

Still, impressively consistent with the GFS at T324 though. Will be interesting to see how FI looks on the 12Z.

[karyo]

Just now, radiohead said:

Of course!

Still, impressively consistent with the GFS at T324 though. Will be interesting to see how FI looks on the 12Z.

Yes, I suppose a northerly is slightly more likely to materialise than an FI easterly.

Something to watch as there is no interest before then.

[booferking]

If only we could get more heights into scandi day 4-5 we would be mighty close to an easterly. 

There is slight trend for increased heights this run but all a little to late likely.

Edited January 1, 2017 by booferking

[karyo]

8 minutes ago, booferking said:

If only we could get more heights into scandi day 4-5 we would be mighty close to an easterly. 

There is slight trend for increased heights this run but all a little to late likely.

Yes, the bitter cold makes a bit more progress westwards thanks to the orientation of the high pressure extending into Scandinavia.

No changes in the Atlantic though. We could have done with a slight shift there.

[cold snap]

UKMO at 144 might be cold ,very different to GFS,high pressure try's to pull out further west

[swfc]

well the 12z at 144 hrs shows possibly the flatest atlantic high ive ever seen

really getting tedious now imo given greece freezes.hopefully mid month may see a change unless dry and frost is your thing