Model output discussion - heading into 2018

[Catacol]

Morning all - cold and frosty here... was woken by the sound of neighbours scraping their car windows... and there is snow on Exmoor - so a better December even for the tropical SW than the last few.

The last couple of days have brought in some more hard data, and a very interesting CPC report on the pacific. Following the disappointment of the collapse of the last MJO phase and resultant loss of confidence in a high lat block forming in the next week or so (though NWP is toying with weak features now.... residual impact of the brief glancing blow with phase 8 ) there is more to be interested in again today. SOI continues to hold moderately negative - indeed the running 30 day average has now dropped to below 0 and shows no sign of reversing yet

https://www.longpaddock.qld.gov.au/seasonalclimateoutlook/southernoscillationindex/30daysoivalues/

This indicates a Nino forcing sitting on top of a Nina base state - and the CPC report this week on the MJO has a bullish tone to it in terms of the next cycle. A couple of quotes here: 

"OLR anomalies based on the GEFS RMM-index forecast are relatively weak during Week-1 as the MJO competes with the base state. During Week-2, the MJO anomaly pattern becomes much stronger."

and

"The constructed analog depicts a robust MJO event emerging over the Indian Ocean during Week-2."

with this comment summarising their thoughts

"If the signal does emerge over the Indian Ocean in Week-2, however, the MJO midlatitude response becomes more robust and would favor a pattern change during the second half of January."

MJO phase 3 would therefore seem logical by mid month, and phase 3 composites for January, posted yesterday, suggest a renewed signal for blocking. If this blocking is to achieve high latitude then amplification will be required. Here we are too early in the cycle to be sure of what may happen with the next pulse of energy... but updates today show the expected path towards renewed possible momentum and something to help try and wobble that jet stream further. Most striking today is the sharp return to neutral of mountain torque.... it will be interesting to see how much further this may climb into positive territory.

So yesterday's discussion of a change by mid month stays on course today. MetO extended mentions weaker signals for a colder regime later in the month - would be pleased to see the text change to a more 50/50 sense of the prognosis in their eyes if the next MJO wave is to impact in January.

In the near term the vortex intensification increases to a generally positive profile at all levels and most latitudes by day 7

and this blunt, but handy, tool showing strat temp shows a return to below average for the first time since early December

My take would be that any NWP output pointing to blocking to the north in the next week to 10 days is ambitious and likely to be blown away by vortex strength. Angle of the jet may possibly produce some more transient events and snow for the usual high ground locations - but otherwise a westerly regime, stormy at times.

Final comment - I take my hat off the long term forecasters who have the bravery to nail their thoughts to a public mast. We know that often they come to grief... but we are all glad nevertheless to have something to work with when trying to forecast, and I hope we have the ability to maintain respect when these forecasts go wrong. We have 2 long range forecasts that pointed to a cold spell in late Jan - Ian Pennell and Roger Smith. Both lay out their methods clearly, and good luck to both of them. I've been a quiet fan of Roger's ability to nail a general pattern for many years now - though his methods totally bamboozle me. So far his winter thoughts have panned out fairly accurately - I hope the call for a very cold second half of January comes to fruition. 

 

[Tim Bland]

Anyone know what’s happened to Euro4? Is it just weather online or is there an issue with the model? 

[ribster]

54 minutes ago, danthetan said:

Noted that the GFS 6Z was completely different @96hr to its 00Z run with the placing of low pressure systems so charts @ 8-10day cant hold much credence

Not sure that makes any sense, I wouldn't expect it to look the same. A more informative analysis would be to compare it to the next 6z run...

Edited December 28, 2017 by ribster

[karyo]

14 minutes ago, Tim Bland said:

Anyone know what’s happened to Euro4? Is it just weather online or is there an issue with the model? 

I'd say an issue with the model as other models are still accessible on weatheronline.

[stodge]

Morning all

Another day, another set of interesting output and I imagine plenty on here will be hanging their Christmas hats on the ECM/GEM 00Z solutions which loom remarkably similar to this observer while GFS is in a very different place.

Here's GEM for North America at T+192:

I think they call it a "Nor'Easter" over there and would be a classic blizzard. The storm ambles NNE and this slowdown of energy out of the CONUS has huge downstream impacts.

ECM 00Z OP at T+192 for North America:

The storm is shallower and therefore moves more quickly but it does allow downstream amplification.

GFS 06Z OP at T+186:

Storm ? What storm ? No storm means the current mobile set up continues with LP formation in northern Canada and secondary formation further south.

 

[nick sussex]

The GFS 06hrs run fails to develop the first amplified wave upstream over the eastern USA but at least has the good grace to develop the second one near the US plains starting around the T192 hrs timeframe .

This second one is important as downstream it helps to carve a more se angle to the jet.

[Sky Full]

Hi to all you like-minded weather enthusiasts on wonderful Netweather....   Hope you all had a great Christmas and even got to see some snow, maybe.  They certainly got more than they bargained for at Stansted Airport...  

Now, I know its frowned upon to post charts from the CFS but it IS a model, after all, and it can't possibly hurt to have a peek beyond FI now and again, just looking for trends, of course!

Imagine my amazement when I saw what the CFS thinks MIGHT happen in mid-January...

   

Just look at that ridge building over Scandi and is that a Murr Sausage I see?  The colder uppers pool nicely over central Europe and then head our way. The easterly sets in at the end of the sequence and in the following frames things get even more interesting!  The best sequence I have seen in a looong while.  What a shame its such a long way out, but who really knows - it might just happen.  In any case, its a very clear illustration that whatever is happening now, the situation can change drastically over only a few days in this country.  With 10 weeks of winter left, a set-up like this could easily hit us with very little warning.  Don't bet against it is all I'm saying.    

[andymusic]

37 minutes ago, karyo said:

I'd say an issue with the model as other models are still accessible on weatheronline.

still accessible - but it's not completing it's calculations on it's last few model runs - just a bit weird - guy doing them taken some time off maybe lol

Edited December 28, 2017 by andymusic

[danthetan]

1 hour ago, ribster said:

Not sure that makes any sense, I wouldn't expect it to look the same. A more informative analysis would be to compare it to the next 6z run...

The point being that the GFS has no consistency as far out as 96 Hrs so what chance has anything beyond that got of being correct. It was an observation.

[phil nw.]

So we continue to see the jet wavering across us during the coming couple of weeks by the looks of things as we continue in this sometimes quite cold westerly setup.

Snowfall possibilities never far away over the north and particularly higher levels and sometimes- as we have seen already this month- further south too.

The end of next week looks interesting for another possible dive south of cold as the upper trough heads  se into europe.Gefs stamps going with this as are the ec clusterings,also shown earlier by MWB.

The warks 2m temp graph showing a dip around that date too

In fact the week following looking quite cold for C.England so hints that the cold air may stick around.

With signs of heights developing  E.Europe towards Scandinavia this would seem quite possible.

 

as the trough is prevented from further eastward progress and energy continues to be directed se across the UK and W.Europe.

On a side note although we see those +ve height anomalies developing further east there is no real sign of a strong high building further north-yet.The majority of ens outputs still favouring a similar west/n.west pattern but at least it keeps us in a regime where further snow and cold is quite possible.

[Snowy Hibbo]

These are some of my thoughts on European Long Range weather, from my blog about Long Range snowfall. I talk about MJO, GWO and the Stratosphere, and potential effects on the teleconnections that matter to Europe and the UK.

The MJO is forecast to have a Phase 2/3 event in the early stages of January on EPS. EC Monthly(below)shows a similar progression, with the cycle continuing to the more favourable phases of 6/7 (for a Sudden Stratospheric Warming event). Phase 3 + 10 days correlates with a +NAO.

GEFS shows a +NAO for the first few days of January, before moving back down to neutral into Mid January. CFS shows a +NAO pattern for all of January and February. That would certainly help the Northern Alps.

The Global Wind Oscillation is currently in Phase 1(below) and has been stalling there for the past week there. I predict that it will move towards Phase 4 in Early January, and reduce the current -AAM. A -AAM is often associated with a -AO type of pattern. However it looks like during Mid January, we could start to see a more +AAM, which would be more +AO like.

EC is showing another disturbance(below) to the stratospheric polar vortex in Early January. This could correlate with a -AO or -NAO, but the vortex isn't warming very much. The disturbance isn't disturbing the vortex enough to form a proper -AO pattern, but it might affect the AAM.

Original blogpost

[Snowy Hibbo]

2 hours ago, Catacol said:

Most striking today is the sharp return to neutral of mountain torque.... it will be interesting to see how much further this may climb into positive territory

I reckon it might climb up a lot....

It all follows this (blunt) chart I made a few days before Christmas. The Phase 1/2 event is currently running longer than I expected, but the GWO will eventually get back on cycle. I might have to adjust the dates though.

The yellow line is my forecast for the GWO.

I will update it tomorrow I think....

Any live shots of the Frictional Torque? WDT haven't fixed the AAM Plots for me yet.

[comet]

Just thinking aloud the warming that Catacol has shown to have taken place at 30mb and possible subsequent geo heights could very well still be showing its hand as it continues to downwell  as we go into January. Normally there is a lag period and we have seen the affects this week of wave breaking and downwelling that occurred around the 9th of the month. The models are still toying with weaker heights to the north and north east which may be traced back to this downwelling . Again the ESRL mean and more especially the anomaly composite charts give perhaps a better idea of what I am referring to

The mean composite chart for the 25th at 70mb where you can see the weakness between the low heights

The anomaly chart for the same time shows the weakness better

The anomaly chart for 23rd Dec at 2OOmb

Now for the 25th of Dec and you can see there is an anomaly for stronger heights over the pole.

The anomaly map of GEO heights are not that strong as can been seen on the mean chart below but are the very  reason the states are seeing the brutal cold wave that is engulfing them.

These slightly higher heights moving across the pole are what the models are trying to portray in the H500 charts over the coming 10 days or so. That is perhaps why we are not seeing the normal west to east zonal or very mild south westerlies that we would normally see under a very strong vortex.

[Pajcov]

Been following this model forum for years since it won me money betting on a white Christmas... thought it was time I joined.. very limited knowledge but love the extremes weather can bring.. especially cold...

[mountain shadow]

Yes the 12z GFS op was that bad. Zonal throughout with occasional Pm incursions. 

Attempts of a sliver of heights over Scandinavia around  t+216 were quickly snuffed out.

[Weathizard]

No posts for 2 and a half hours in amongst the 12z's says it all! Blimey that's up there with the lowest of the low, model thread wise. Harks back to the nightmare winters of the recent past.

Have only just checked the latest, pretty awful viewing... raging vortex over Greenland showing no real sign of moving. Like the annoying in law that stubbornly refuses to leave.

[ACCOUNT DELETED]

5 minutes ago, mountain shadow said:

Yes the 12z GFS op was that bad. Zonal throughout with occasional Pm incursions. 

Attempts of a sliver of heights over Scandinavia around  t+216 were quickly snuffed out.

It still looks like it could turn colder by the end of next week though don't you think?

[knocker]

11-15d looking like a classic La Nina +NAO configuration. This pattern means warmer temperatures for the East heading towards mid-January H/t MV

[Captain Shortwave]

At this juncture I think the only issue here is whether that weak high develops to our north east which is currently at the 8-10 day range. Now we have the GFS and GEM developing this now. We will have to wait a few days for the ramifications of this but I doubt much can be taken from a low resolution operational output.

So the fact we have model output starting to consistently build that weak high is a start at least. It could disappear on the model output or remain with a diffrrent path taken beyond this point.

Edited December 28, 2017 by Captain Shortwave
Charts

[Ali1977]

Not sure why so few comments on the 12z, no cold from the East or even the North but some pretty cold days here and there from the NW, with more chance of snow in many places (although prob melting the next day). Could be much worse!!

edit - GEFS still of interest in FI - several showing a developing Arctic high and a few attempting PV split. 

Edited December 28, 2017 by Ali1977

[bluearmy]

15 minutes ago, knocker said:

11-15d looking like a classic La Nina +NAO configuration. This pattern means warmer temperatures for the East heading towards mid-January H/t MV

Registers at average +1 so hardly a roaring return. TBH, I was taken on recent suites across extended ens  modelling that nao was fairly neutral and on the gefs actually more negative than positively neutral 

[Weather-history]

20 minutes ago, knocker said:

11-15d looking like a classic La Nina +NAO configuration. This pattern means warmer temperatures for the East heading towards mid-January H/t MV

What strikes me is the higher pressure anomaly run towards Newfoundland on that chart. That screams cold zonality to me or at least only short term tropical maritime incursions. 

[nick sussex]

Strange to see the thread so quiet after the GFS  12 hrs run has increased the amplitude upstream and the trend in terms of developing a battleground scenario has increased.

NOAA have commented on a big change re the speed of the upstream pattern, and you can clearly see this if you compare ECM op runs of a few days back .

The Pacific area looks like it’s being effected by the MJO movement which is feeding into the upstream pattern to increase the amplitude and consequently slow that.

The GEFS have been slow to react and the GFS op runs  until recently failed to develop the ne USA coastal low which is the bellwether moving forward .

Regarding the MJO NOAA have more faith in the ECM projections  which might be why that was the first to pick up on the amplification increase.

 

Edited December 28, 2017 by nick sussex

[knocker]

Looks like there or thereabouts for mjo phase 2

[bluearmy]

10 minutes ago, nick sussex said:

Strange to see the thread so quiet after the GFS  12 hrs run has increased the amplitude upstream and the trend in terms of developing a battleground scenario has increased.

NOAA have commented on a big change re the speed of the upstream pattern, and you can clearly see this if you compare ECM op runs of a few days back .

The Pacific area looks like it’s being effected by the MJO movement which is feeding into the upstream pattern to increase the amplitude and consequently slow that.

The GEFS have been slow to react and the GFS op runs  until recently failed to develop the ne USA coastal low which is the bellwether moving forward .

 The gefs 12z have decent continuity with the previous run - jet angled nw/se into Europe with the uk probably under the mean trough - could easily be fairly wintry. in fact, given that we are looking at a strong zonal flow heading down through the strat by day 10, surprising how the AO and NAO manage to be negative in the 11/16 day period and there is plenty of northern blocking evident on the gefs members. maybe day 16 is too soon for the trop to respond to the increased flow higher up. That goes against the theory that we won't see any n blocking evident before day 16.