Model output discussion - 16th Nov onwards

[Rocheydub]

This is one mighty deep low heading towards Iceland a week today on the 06z down to 920mb?

 

Let's hope that it's just the GFS doing its usual and over deepening these LP systems, otherwise that will do severe damage!

[Man With Beard]

Also on the GFS 06Z - isn't this very early in the season for an Atlantic-sourced front to be so cold? Is this the affect of lower SSTs? (though low temps may be dumbed down nearer the time, of course)

If so, I wonder how cold a PM burst in Jan/Feb will be.

Accordingly, back-edge hill snow flagged up as a possibility.

[John Badrick]

well, i dont know but when you look at the archive charts in the lead up to it (probably the most famous winter in living memory), it seems to pop up out of nowhere. the weather seemed to change from standard zonal to epic winter very quickly. the notable point was the strong siberian high at the same timeframe it is showing today. it would be interesting to look back at the ENSO state and solar output etc back then. i might do so when i get time.[/quote

Please do, would be very interesting to know. Around what date in 1962 did the weather start changing?

[Nouska]

<snipped>

 

Worth noting the lack of Azores High displacement into Europe, too. It's a bit more like a CP El Nino so perhaps a reflection of the hybrid El Nino characteristics we see in the Pacific at the moment, whereas a Euro High is more a characteristic of a 'classic' (EP) type event. This is, however, an idea that's just popped into my head and requires scientific verification!

 

I thought that too but a very simple two year composite of the two strongest EN events, yields this for December.

 

A good read in the last post by Knocker, on the ENSO thread - experts are very unsure of where this event will lead.

 

https://forum.netweather.tv/topic/79367-enso-discussion/?p=3287363

 

The ECM Reading ensembles should still be updating on my previous post   ....   

 

https://forum.netweather.tv/topic/84434-model-output-discussion-cold-snap-incoming-16th-nov-onwards/?p=3289758 

 

That's a big spread of options in the later stages.

[VillagePlank]

Lorenzo, is anyone still trying to make use of the OPI, and if not, did anyone work out what was being used to calculate it, and if so, is it possible last year was a blip for UK/Europe and maybe this year it would have more usefulness? I couldn't find anything recent by searching online myself, but maybe someone knows?

 

I looked at it last year. It might have been modified, forgot which seasons where winter, and I could only get approximate data. Here's what I found,

 

https://forum.netweather.tv/topic/81494-october-pattern-index-opi-monitoring-winter-season-2014-2015/page-60#entry3063183

[nick sussex]

On the face of it nothing much to get excited about if you're looking for some extended wintry weather. The PV now energized is likely to remain to the north for some time.

 

The uncertainty currently is where the jet will sit in terms of how far north/south and of course this will effect chances of some PM air and also what the Euro high might do.

 

The operationals have played with taking this further north which of course isn't great for any PM air however the ensembles have been split here. You can see by the means especially in the ECM that the majority keep the Euro high further to the west/sw. The range of solutions looking at the spreads is high across the UK and northern Europe so its this that's more the issue of uncertainty moving forward.

 

The upstream pattern although progressive is still expected to develop occasionally more amplified low pressure systems, NCEP also suggest that the eastwards movement might slow. So perhaps a bit more amplified than is currently being shown.

 

 GIVEN THE
BLOCKINESS OF THE WRN NOAM PATTERN INTO DAY 6 SUN IT WOULD NOT BE
SURPRISING IF FUTURE GUIDANCE TRENDS SOMEWHAT SLOWER WITH EWD
TIMING BY DAY 7 MON.

 

It seems from NCEP that the ensembles are generally showing a flatter picture because of non-reaction to whats normally expected by the teleconnections, the suggestion of eastern USA troughing does impact Europe especially in terms of the movement of the Azores high, if that troughing does appear then the amplitude of that will determine whether this pulls further west and north.

 

Overall I think patience is going to be needed for those looking for something that has crispy dry snow and much colder conditions however I wouldn't rule out some briefer colder snaps associated with PM air, things might get a touch more interesting towards day 10 if we can find more amplitude over the eastern USA. However its hard to see anything lasting for too long given those low heights to the north-west.
 

Edited November 23, 2015 by nick sussex

[bradymk]

A possible growing anticyclonic signal as we move into December according to GEFS. 

[Mark Parsons]

A possible growing anticyclonic signal as we move into December according to GEFS.

Blowtorch or no blowtorch that is the question?

[bradymk]

Blowtorch or no blowtorch that is the question?

That would depend on the location of any high. Must note though that i am not saying it is going to turn more anticyclonic towards the second week of Decemeber, just a potential signal i saw when flicking through the GEFS suite just now.

[John Badrick]

well, i dont know but when you look at the archive charts in the lead up to it (probably the most famous winter in living memory), it seems to pop up out of nowhere. the weather seemed to change from standard zonal to epic winter very quickly. the notable point was the strong siberian high at the same timeframe it is showing today. it would be interesting to look back at the ENSO state and solar output etc back then. i might do so when i get time.[/quote

Please do, would be very interesting to know. Around what date in 1962 did the weather start changing?

Similar solar output

[knocker]

On 22 December. A high pressure system moved to the north-east of the British Isles, dragging bitterly cold winds across the country.

 

A belt of rain over northern Scotland on 24 December turned to snow as it moved south, giving Glasgow its first white Christmas since 1938. The snow-belt reached southern England on Boxing Day and parked over the country, bringing a snowfall of up to 30 cm.

 

After that it was downhill on a handcart.

 

UK winter 1962-3 in 20CR

 

This video shows sea-level pressure (black contours), 10m wind speed and direction (arrows), and 2m temperature anomaly (arrow colours), from the 20th Century reanalysis. The uncertainties for this time and place are small, so we can have confidence in the circulation reconstructions, and we do indeed see the southern UK being dominated by cold easterlies, particularly in January (the coldest month).

 

http://reanalyses.org/atmosphere/uk-winter-1962-3-20cr

Edited November 23, 2015 by knocker

[Ali1977]

I have to admit that when looking at the GEFS suite in FI, NH +384 panel I didn't expect to see a set of really quite interesting charts.  Several with blocking setting up over Greenland, Several with high pressure moving in over the UK (which could migrate North), and several with Blocking of some sorts developing over the pole (mainly Alaska/Siberia side).

Whilst not many are showing beasts or Severe Arctic winds on our shore, they do show the polar vortex broken and moving away from Greenland.  Something to keep an eye on, and also something maybe a foot.  

If someone please post the Z500 Panel at 384 for the NH that would be much appreciated, also, what do anyone with more experience than me think on this??

[Polar Maritime]

Just a 'polite' reminder that there is a Historic Weather thread here: https://forum.netweather.tv/forum/40-historic-weather/ 

 

Past Winters thread open here:  https://forum.netweather.tv/topic/84396-past-winters-discussion/

 

And a Winter 2015 thread open here: https://forum.netweather.tv/topic/84402-winter-201516-the-final-countdown/

 

For all Winter musings other than Model 'Output'    

 

Thanks. PM.

Edited November 23, 2015 by Polar Maritime

[bryan629]

I have to admit that when looking at the GEFS suite in FI, NH +384 panel I didn't expect to see a set of really quite interesting charts.  Several with blocking setting up over Greenland, Several with high pressure moving in over the UK (which could migrate North), and several with Blocking of some sorts developing over the pole (mainly Alaska/Siberia side).

Whilst not many are showing beasts or Severe Arctic winds on our shore, they do show the polar vortex broken and moving away from Greenland.  Something to keep an eye on, and also something maybe a foot.  

If someone please post the Z500 Panel at 384 for the NH that would be much appreciated, also, what do anyone with more experience than me think on this??

Here you go Ali 

http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=3&mode=6&ech=384

[carinthian]

Latest GFS wants to see dreaded Euro High back again in December. Not sure that will be the case, but will let you know our thoughts tomorrow. Freezing hard here at the moment with snow guns on full blast !

 C

[Liam J]

Latest GFS wants to see dreaded Euro High back again in December. Not sure that will be the case, but will let you know our thoughts tomorrow. Freezing hard here at the moment with snow guns on full blast !

 C

GFS is being very bullish bringing the Euro high back as we move towards December, could be a rain maker for parts of the UK as weather fronts and depressions run up against it with a long draw SW'ly, if it comes off.... 

 

[TSNWK]

Two posts in 2 hours, back end of November as the 12z run emerge - tell Mobile phone users all they need to know without burning up their allowance by downloading the charts..

[Singularity]

I thought that too but a very simple two year composite of the two strongest EN events, yields this for December.

 

A good read in the last post by Knocker, on the ENSO thread - experts are very unsure of where this event will lead.

 

https://forum.netweather.tv/topic/79367-enso-discussion/?p=3287363

 

The ECM Reading ensembles should still be updating on my previous post   ....   

 

https://forum.netweather.tv/topic/84434-model-output-discussion-cold-snap-incoming-16th-nov-onwards/?p=3289758 

 

That's a big spread of options in the later stages.

 

Good points, and this is why I tend to look at this year as being ahead of the usual cycle, as we've seen the AH displacement quite a bit already when usually it starts to become frequent in January. Just a theory though, built from the fact that this event seemed to get underway a bit earlier in the year than most, and escalated unusually fast to achieve record strong atmospheric signature relative to the time of year in July.

 

It sure seems that faith in longer range output should be set even lower than usual. We're going to need bigger buckets of salt...   

 

For example, it's hard to anticipate which model has the situation over Siberia handled correctly in the 7-10 day period at the moment. The comment from NCEP implying a more amplified outcome being probable does lend support to ECM 00 and GFS 06z det. runs over the GFS 00z and 12z det. runs, but a blend of the two outcomes is also possible.

 

I was a bit disappointed by the relatively low magnitude of wave breaking achieved by the GFS 06z det. despite its similarities to the ECM 00z det; it suggests that the GFS det. runs of a few days ago were being too optimistic with the alignment of the blocking highs. With a lot of 'standard' weather conditions on offer during the next 7-14 days, I'm daring to hope for the swift return fo some more interesting strat. output to discuss.

[SLEETY]

Two posts in 2 hours, back end of November as the 12z run emerge - tell Mobile phone users all they need to know without burning up their allowance by downloading the charts..

yes hehe thx for that,looks like euro trash high becoming the dominant  force again   

Edited November 23, 2015 by SLEETY

[Liam J]

Some horror show charts on offer, if we look back to winter 1997/98 which was the last El Nino year with comparable strength, I'm not sure but could this be a typical El Nino type pattern emerging? 

[Ali1977]

Will be an interesting update later from Cohen...assume it's related to Siberian high

Judah Cohen

Judah Cohen – â€@judah47

@WinterExpert What I am talking about would not show up on the weather models. Check my AO blog by tomorrow.

Something gives me the feeling that a big swing in the weather may happen around Xmas....FI charts are in the "revert to Zonal phase" , still not picking up Siberian snow cover and lowering sun activity influences...I think the GEFS are best to follow in FI for now.

[John Badrick]

Some horror show charts on offer, if we look back to winter 1997/98 which was the last El Nino year with comparable strength, I'm not sure but could this be a typical El Nino type pattern emerging?

El Niño just one piece of the puzzle, lots of other differing teleconnections that make this year unique

[Cheshire Freeze]

Something gives me the feeling that a big swing in the weather may happen around Xmas....FI charts are in the "revert to Zonal phase" , still not picking up Siberian snow cover and lowering sun activity influences...I think the GEFS are best to follow in FI for now.

 

Model output all fairly normal at the moment and following the trajectory nicely, it's kind of a waiting game at the moment and certainly quite normal to see a temporary power up of the vortex. How long are we looking at until the next period of interest rears its head in the shorter and medium range modelling?? I'd say probably about 2 weeks with the period of interest Mid-late December-seems a decent enough estimate of a landing point. Should have a good idea of where we're headed stratospherically by then too. As Singularity has pointed out, we seem slightly ahead of the curve this year and I'm struggling to keep remembering it's only late Nov!

 

Also, from the snippet I've just read, it seems Cohen expects the AO to tank at some time in the not too distant future. The evidence seems to suggest that the vortex will wind itself up only to pop like a balloon. It may be a wQBO and a nino fuelled stratospheric vortex but as they say, those that are biggest fall the hardest. All very interesting...

Edited November 23, 2015 by CreweCold

[Ali1977]

Again, not a zonal fest....

If on a mobile phone, turn to see picture properly if you have clicked on the image.

Edited November 23, 2015 by Ali1977

[SLEETY]

Will be an interesting update later from Cohen...assume it's related to Siberian high

Judah Cohen

Judah Cohen – â€@judah47

@WinterExpert What I am talking about would not show up on the weather models. Check my AO blog by tomorrow.

where you find this information,i want to read it