Model output discussion - winter proper underway

[feb1991blizzard]

If ever we needed a good 46 its tonight, by 13 minutes past 10, will it be crying into our beers or will we be back in the game, cant see week 3 being any good after the ext EPS 0z, 12z ext EPS not filling me with confidence either I'm afraid.

[shotski]

Hi Feb, I assume you mean the ECM 46 day update ? Do you have access to this model. 

Thanks

[ANYWEATHER]

Evening! Tonights gfs is not without interest for Christmas day albeit a long way off ! If the chart Ive posted tonight comes very close some people will see a White Christmas , especially with some elevation ,and it does not have to be that cold to snow! After that well both models gfs and ecm pump up the jet stream between xmzs and new year which has been on the model output for some days now, and nothing showing anything really mild.....I will follow with interest

[bluearmy]

2 minutes ago, feb1991blizzard said:

If ever we needed a good 46 its tonight, by 13 minutes past 10, will it be crying into our beers or will we be back in the game, cant see week 3 being any good after the ext EPS 0z, 12z ext EPS not filling me with confidence either I'm afraid.

The 46 gets a fair bashing on here - i suspect week 3 is worth attention and perhaps week 4 at a push but thereafter it’s surely of no use to us without clusters and in house meto models to compare with

the extended eps are playing around with a more defined e sceuro upper ridge - probably a response to the e Atlantic trough 

the spreads on the eps lose the definition on the Alaskan ridge to greeny by day 8 with no guidance beyond there. Day 10 reveals a solid s greeny low height blob and the jet having every chance of heading well south into Iberia 

[feb1991blizzard]

Just now, shotski said:

Hi Feb, I assume you mean the ECM 46 day update ? Do you have access to this model. 

Thanks

We all do, but others some will have the whole hemisphere chart, we only have NW European / East atlantic view.

[phil nw.]

Just for interest really a look at the gef day 15 spreads

3 main features are the areas of greatest spread in possible outcomes(yellows/oranges).This far out of course we will see such a range but the point is that there is greater certainty of retaining low heights to our north which is the one area where we want change if looking to a possible cold setup.

The eastern heights where they show on the gefs stamps are generally too far east in order to bring cold from that direction.At the moment i would settle for a euro trough digging se and a little ridging to the west-a slider at this time of year might just be cold enough for lowland snow even from the north west.

 

Edited December 18, 2017 by phil nw.

[feb1991blizzard]

2 minutes ago, bluearmy said:

The 46 gets a fair bashing on here - i suspect week 3 is worth attention and perhaps week 4 at a push but thereafter it’s surely of no use to us without clusters and in house meto models to compare with

the extended eps are playing around with a more defined e sceuro upper ridge - probably a response to the e Atlantic trough 

the spreads on the eps lose the definition on the Alaskan ridge to greeny by day 8 with no guidance beyond there. Day 10 reveals a solid s greeny low height blob and the jet having every chance of heading well south into Iberia 

You've hit the nail on the head though - EAST sceuro, if it became reality, not sure I could see it ever backing west enough to become effective anytime soon, id still rather have it there though to drive some more ridging into the pole, albeit probably not at a perfect angle, but you would think some stratospheric impact would occur.

[bluearmy]

2 minutes ago, feb1991blizzard said:

You've hit the nail on the head though - EAST sceuro, if it became reality, not sure I could see it ever backing west enough to become effective anytime soon, id still rather have it there though to drive some more ridging into the pole, albeit probably not at a perfect angle, but you would think some stratospheric impact would occur.

Indeed 

the charts are mean and the clusters will reveal later how much support there is for dropping the jet far enough south to allow this ridge to back west across the top 

 

[nick sussex]

Good and bad news from the NCEP MJO update:

 The active phase of the MJO is currently approaching the Western Hemisphere, but is interfering with the background La Niña state that is suppressing convection near the Date Line.

 Models show eastward propagation of the MJO envelope for at least the next week or so, before diverging on whether the signal will weaken or continue across the Western Hemisphere.

 Some caution should be taken with the aforementioned model forecasts that show a weak MJO over the Western Hemisphere, as low frequency enhanced convection building over the Maritime Continent in association with La Niña could be biasing the RMM index towards Phases 4/5 and away from Phases 8/1.

 Even if the MJO does make it across the Western Hemisphere, any substantive extratropical teleconnections are unlikely until the signal reaches the Indian Ocean.
 

So good news that the models might have the MJO too weak  but not so good that the impacts might currently be muted and not appear till progression to the Indian Ocean.

[damianslaw]

Have taken a few days off model watching, and was expecting an amplified flow to be showing for the last few days of the month, alas what do I know.... the models have reverted to a very mobile flow to end the month, more mobile for quite some time, perhaps stormy conditions on occasion, heavy bouts of rain, some colder air in the north at times, wintry precipitation higher ground, perhaps lower levels as next week wears on.

Whether this is a major sustained change, or just a temporary mobile blip remains to be seen. I'm reminded of 2008 and 2012 in some respects, winters that produced a cold wintry start, then were mild and unsettled for a little while, more pronounced in 2012, but then the cold came back... late Dec in 2008, early Jan in 2013..

Typically late December is very unsettled, and this now looks like the seventh christmas in a row, with a run in that is predominantly mild and unsettled - all a bit rubbish for those liking seasonal cold conditions, but at least this year we've all had some of that already, something we haven't been able to say since 2012. Longer term - signs jet will dig ever south, so colder unsettled rather than mild unsettled could see in the New Year.

With the forecast pattern, I suspect this thread will be quiet in the days leading up to christmas, but my hunch is this is not a long-lasting trend for the rest of the winter, lots more twists and sudden changes ahead.

[winterof79]

1 hour ago, shotski said:

Hi Feb, I assume you mean the ECM 46 day update ? Do you have access to this model. 

Thanks

 I wonder do we have any stats on the ECM 46 day verification over winters gone by? Matt Hugo used to roll it out regularly but I am less than convinced.

Edited December 18, 2017 by winterof79

[ArHu3]

1 minute ago, winterof79 said:

 I wonder do we have any stats on the ECM 46 day verification over winters gone by?

From experience the broad (z500 anomaly)  pattern is generally correct but the devil is in the details and a small  shift can make a huge difference and the more south and west the more impact the little details can make 

[comet]

Fully expected to see a stronger ridge pushing into the Arctic and would expect to see further strengthening in the runs to come. This courtesy of wave breaking into the strat several days ago and downwelling into the trop, Regardless of the AAM and GWO budgets. Models could, repeat could look very different in a couple of days time. Not in time to prevent a green Christmas though for most people.

Edited December 18, 2017 by comet

[Catacol]

GWO holding the faith.... with return to phase 4 underway and AAM budget holding up - the monthly cycles very clear and climbing overall.

Confidence therefore sustained on models gradually picking up on a scandy ridge as we approach New Year. Typhoon interference close to Philippines may be interfering with the MJO forecast - but it looks to maintain a steady march towards phase 8. Extended EPS firmer on height rises to the NE today as part of an ongoing trend over the last few days

with possibility of associated wave 2 forcing on the trop vortex and considerably interest in resultant patterns. GFS op today is on the right lines I think in the extended... and I dont think it will be too long before some cold permutations start to win through in the ensembles. 

Where might we end up as we move through the first half of January? Well - I'm going to be a bit sneaky here. :-) From various sources I have read theories around 4 composite years for the current pattern: 1963, 1985, 1996 and 2006. Plotting the January anomaly for those 4 possible matches we get this:

I think we'd all take that from a coldie perspective... but there is a long way to go yet.

[Daniel*]

A bit irrelevant but speaking wrt to early discussion. A PV chunk/lobe paid us a visit 7 years ago to this day, I believe there was quite disruptive, snowfall across large swathes of country.

Wouldn’t it be great to see the same again..

[feb1991blizzard]

30 minutes ago, nick sussex said:

Good and bad news from the NCEP MJO update:

 The active phase of the MJO is currently approaching the Western Hemisphere, but is interfering with the background La Niña state that is suppressing convection near the Date Line.

 Models show eastward propagation of the MJO envelope for at least the next week or so, before diverging on whether the signal will weaken or continue across the Western Hemisphere.

 Some caution should be taken with the aforementioned model forecasts that show a weak MJO over the Western Hemisphere, as low frequency enhanced convection building over the Maritime Continent in association with La Niña could be biasing the RMM index towards Phases 4/5 and away from Phases 8/1.

 Even if the MJO does make it across the Western Hemisphere, any substantive extratropical teleconnections are unlikely until the signal reaches the Indian Ocean.
 

So good news that the models might have the MJO too weak  but not so good that the impacts might currently be muted and not appear till progression to the Indian Ocean.

Could that also be good news also in a way though Nick in that we may have found the reason the models dropped the scandi high solution and that the Met Office forecast was adjusted and that the signal is just delayed and some more amplified solutions but with a less threatening PV might start appearing again in a few days time again in the Ensembles and GFS FI.

[Catacol]

34 minutes ago, nick sussex said:

Good and bad news from the NCEP MJO update:

 The active phase of the MJO is currently approaching the Western Hemisphere, but is interfering with the background La Niña state that is suppressing convection near the Date Line.

 Models show eastward propagation of the MJO envelope for at least the next week or so, before diverging on whether the signal will weaken or continue across the Western Hemisphere.

 Some caution should be taken with the aforementioned model forecasts that show a weak MJO over the Western Hemisphere, as low frequency enhanced convection building over the Maritime Continent in association with La Niña could be biasing the RMM index towards Phases 4/5 and away from Phases 8/1.

 Even if the MJO does make it across the Western Hemisphere, any substantive extratropical teleconnections are unlikely until the signal reaches the Indian Ocean.
 

So good news that the models might have the MJO too weak  but not so good that the impacts might currently be muted and not appear till progression to the Indian Ocean.

Phase 7/8 impacts are all we need at present - I'd rather not project too far forwards at the moment as renewed teleconnective impact from the Indian Ocean would suppress the blocking signal. The longer it sits in 7/8 the better, and GWO orbit suggests it is playing its part in maintaining sufficient amplification to support an interesting looking January.

Where did you get the update? It's still stuck on 11th December over at the CPC.

[tight isobar]

Indeed...given current aspects..

7-into p/8 mjo would likely be the safe-cracker....

Anyway...ops are trying hard to pick the signal....

And its looking mouth-watering into the new yr!!!...

Edit: possibly.

Edited December 18, 2017 by tight isobar

[bluearmy]

Looking at the latest Beeb 10 pm forecast, seems they expect the trough to get to the east and a lee northerly to come down later next week. MOGREPS must be on this page - need to revisit the eps clusters ..........

[nick sussex]

13 minutes ago, Catacol said:

Phase 7/8 impacts are all we need at present - I'd rather not project too far forwards at the moment as renewed teleconnective impact from the Indian Ocean would suppress the blocking signal. The longer it sits in 7/8 the better, and GWO orbit suggests it is playing its part in maintaining sufficient amplification to support an interesting looking January.

Where did you get the update? It's still stuck on 11th December over at the CPC.

You might just need to refresh or alternatively if you put NCEP MJO update in your search engine you get the direct link and go to the PDF one. I just checked again and that works fine.

[northwestsnow]

6 minutes ago, bluearmy said:

Looking at the latest Beeb 10 pm forecast, seems they expect the trough to get to the east and a lee northerly to come down later next week. MOGREPS must be on this page - need to revisit the eps clusters ..........

WOW -thats very unexpected news Blue?!?!!?

[bluearmy]

The 46 on the limited view we get on Icelandic site shows the low heights becoming more nw/se as high anomoly grows to our ne - will await the global view on that 

the vortex seems to be heading towards Baffin as higher anomolys show over Newfoundland 

[tight isobar]

Pac ridge via 18z...continues to force into the pole!!

The jet gaining energy of us-seaboard...

Some notable interact-on the canadian lobe...

And we need that jet firing into iberia/or northern africa...as pv-makes tracks east....

Expect cold upgrades all around if modeling keeps the direction!!!!

Edited December 18, 2017 by tight isobar

[bluearmy]

The 18z takes the central USA plains temps to numbers which could be a record low ??.uppers of -30c into  n Kansas/Missouri !!!!

[feb1991blizzard]