Model Output Discussion 01/09/17

[That ECM]

Gfs looking more like ukmo from this morning? Either way the theme continues. Could be a good start to the Bournemouth ski season ^^^ snap shortwave

Edited November 25, 2017 by That ECM

[tight isobar]

Much better early on..

We are most like getting the morph..

Every option is feasible...

And cold.....

6z.

Link coming?

[tight isobar]

As the ridge displaces' and cuts the flow via the north...850s..

Its tunes into scandi and taps into the flow there....

Its all gravy where-ever you look.

Edited November 25, 2017 by tight isobar

[Methuselah]

If the last few days' outputs are anything to go by (the 12Z and 18Z being 'better' than the 0Z and 06Z?) this afternoon's runs should be 'epic'...?

Now watch it all go pear-shaped...and bring on the BOM...

[Strider]

These are definitely the most promising charts we have seen at this time of year since 2010 - could we be set for a sensational start to winter 17/18?

 

GFS06z op showing the block slightly further north, leading to a trough undercutting from the east.

Edited November 25, 2017 by Strider

[karlos1983]

Could do with that short wave not appearing east of Greenland but maybe that’s being picky 

[Ice Day]

Just now, tight isobar said:

As the ridge displaces' and cuts the flow via the north...850s..

Its tunes into scandi and taps into the flow there....

Its all gravy where-ever you look.

That's the theme over the last few days.  When a model goes 'off-script' it still seems to end up in a cold outcome.  Atlantic is completely shut down at 162

  

[Weathizard]

Interesting differences this run between day 4-6, more energy going over the top of the Atlantic ridge but still not really harming the situation, could be another peach in FI

[swfc]

The only problem "if there ia one" is the run looses the more sustainable heights coming out of the esb.possibly a bit picky but it may stir things up ie low existing there.still good modeling for cold.hmmm850s on the way down and going into esb and pumping up the pv.bit flat imo but early days 

Edited November 25, 2017 by swfc

[Iceaxecrampon]

06Z

Thursday +120

Decent Chart - midweek onwards looks interesting even "dahn saaf".

[nick sussex]

Upgrades all round this morning which is great to see.

Better trough disruption to the west keeps the high further north.  The ECM is now evolving differently with hints of retrogression and a Scandi trough.

The UKMO is a huge upgrade on last night its T168hrs even with the restricted view is excellent.

If retrogression is going to be the trend then any easterly even if it appears will be short however that's not bad because you might still end up with a northerly after.

Things might get a bit messy for a while till the models catch onto the correct evolution but overall some positive signs this morning for coldies.

 

[Geordiesnow]

Its one of those outputs where even though there is signs of perhaps the Atlantic ridge will start to collapse, i just would not say its a definate by any means as the models can easily switch in respect of prolonging the ridge which will keep us in the cold air for longer.

Either way, a cold Northerly is definately coming up and the ECM is showing more colder uppers coming into the mix, nothing spectacular for the time of year but perhaps just about cold enough for snow showers down eastern coasts aslong the wind stays off shore.

[Catacol]

58 minutes ago, bluearmy said:

Away from th stats, the extended eps rebuild the mid Atlantic ridge and end up akin to the gefs as we head through week 2

Yes - not a time to start jumping up and down at the moment yet to be honest... but the sustained modelling of the greenland ridge could be very important going forward, particularly if the north pacific ridge establishes in situ concurrently. Strat could have a very tough time if that sustains for any length - a couple of posts on the strat thread this morning quietly suggest as much.

The safe money, and possibly still the safe money, would be to forecast a downstream return of jet energy on the back of the north pacific Nina ridge development and the gradual squashing of the greenland ridge... but the ensemble modelling of this is taking longer than I expected and the CFS prediction for Dec is another pause for thought. However model output could all reverse in a hurry if the Nina signal takes control - and everyone on here needs to be aware that this is distinctly likely. 2010 was a very rare setup as we know and unlikely to repeat...

... and yet our Nina is less strong than 2010, our strat is perturbed and we have a combo of falling solar and eQBO. So - who knows for sure? Definitely not I. This is what makes analysis of the pattern so interesting, whatever your weather persuasion.

Edited November 25, 2017 by Catacol

[Frosty.]

Just looking at next week, the Gfs 6z shows a potent arctic plunge for this time of year with snow showers, especially to exposed n / e areas with maxima only a few degrees above freezing and widespread frosty nights..impressive stuff!

Even this weekend, although temps on the thermometer will be at 6's and 7's..add in the windchill and it feels almost subzero, even more so next week if this verifies!

Edited November 25, 2017 by Frosty.

[bluearmy]

06z presents a good opportunity to see what gfs deep fi does re projected amplification from a quite different starting point upstream 

[Gavin Hannah]

I remember 2009 when we got that easterly (or was it greenie) on the 24th December. I'm in no way disappointed with whats coming, but if it was happening only 3-4 weeks from now. Boom!   What I like about the models just now is the consistency for a sustained cold setup. If this lasts all the way to Xmas, then it will be one of the best Xmas lead ups I can remember.  Even if low levels don't get the  quantity of snow of 2009 / 2010, it would feel truly festive compared with recent years.

Edited November 25, 2017 by Gavin Hannah

[swfc]

The gfs and ecm on the oz at 240hrs are basically in the same ball park. 6z gfs is either picking up a new signal or very wrong.that said its out of the reliable but its a big shift before that dropping the high eastwards!!!

[feb1991blizzard]

5 minutes ago, bluearmy said:

06z presents a good opportunity to see what gfs deep fi does re projected amplification from a quite different starting point upstream 

Yes, if it could somehow snatch victory from this mess then you know the atmosphere is primed for Greenland blocking in December.

EDIT : and it is going to!!!

Edited November 25, 2017 by feb1991blizzard

[nick sussex]

Latest from NOAA:

...PATTERN ASSESSMENT AND MODEL CHOICES...

INDIVIDUAL MODEL SOLUTIONS CONTINUE TO DIFFER BETWEEN EACH OTHER
AND FROM RUN TO RUN FOR IMPORTANT DETAILS, BUT ULTIMATELY THE
PATTERN EVOLUTION AND BEST APPROACH FOR REPRESENTING THE MOST
LIKELY SCENARIO FOR EACH DAY DURING THE EXTENDED PERIOD HAVE
CHANGED LITTLE OVER THE PAST 12-24 HOURS.

GUIDANCE AGREEMENT MAINTAINS RELATIVELY HIGH CONFIDENCE FOR THE
LARGEST SCALE ASPECTS OF THE FORECAST.  EXPECT A PROGRESSIVE WAVE
TRAIN TO BECOME ESTABLISHED ALL THE WAY FROM THE WESTERN PACIFIC
ACROSS NORTH AMERICA, THEN SLOWING AND SPLITTING AROUND A
PERSISTENT BLOCK OVER THE MIDDLE ATLANTIC OCEAN.

[Duane S.]

With NH as completely disorganised as it is, we are likely heading into one of rare situations when (unless we get unlucky, as if ?)all roads lead to cold.

It seems like an even bigger Mid Atlantic amplification shot (following on from the one next week)  is being toyed with as well by the models. Worth keeping an eye on, that would have potential of dragging down some seriously cold uppers.

[Singularity]

Late on the scene this morning. Amazing how the Svalbard low has been adjusted in just the right way to increase the amount of cold air sent our way for the middle part of next week!

Other key themes I can see are  the vortex continuing to have a lot of trouble even as the current Arctic blocking spell takes a breather, which raises the possibility of the Atlantic troughs either disrupting as they advance (GFS 00z) or performing another dive via another round of amplification upstream (ECM 00z).

The 06z GFS is looking a bit dodgy as of +216, so perhaps it will be the least appealing run of the day from that model, much as it was yesterday. Not convinced it has the right idea taking so much of a LP system through far-N. Greenland in the 5-6 day range. This takes down the 'bridge-ridge' scenario that could see the mid-Atlantic and NW. Asian highs link up for a bit, which would do us nicely given the cold pool already imported by that time. A little (pleasantly) surprised to see UKMO making the most of that possibility this morning.

Certainly a lack of coherent westerly jet stream even in the GFS 06z at the range I just mentioned.

 In the stratosphere, the height rise associated with the warming event begins at +216 now, and the significant advancement of this toward N. America plus a little poleward (important, that part) begins at +264. This is earlier than yesterday's runs so the event is moving closer in time. 

This... well, we can dream.

GFS 06z slightly stronger with the 30 hPa height rises as of +240. This run of the day does tend to make the most of such events though, for some reason.

Meanwhile in the troposphere its all a bit unclear really. We've got our own high, not quite far NE enough to be pleasantly cold with frosty nights, there are low heights to the NW but not very much so and with an extreme lack of consolidation, and there's a low attempting to cut-off near the Azores and support height rises N. of it (toward Iceland).

Ah - the +264 t o +288 confirms this height rise 

 

A 'holding pattern' you might say... okay if we get the significant stratospheric events unfolding. The 30 hPa progression still looks very nice but has now become a little slower on this run despite having been ahead of the 00z at +240. Much remains to be resolved!

[karlos1983]

Hello PV lobe, welcome to the neighbourhood put your feet up, get comfortable and unleash your fury on our little island will you 

 

Edited November 25, 2017 by karlos1983

[Gavin Hannah]

1 minute ago, karlos1983 said:

Hello PV lobe, welcome to the neighbourhood put your feet up, get comfortable and unleash your fury on our little island will you 

 

That is a stonker of a chart. That would bring serious amounts of snow to quite a few locations! Not just on the mountains.

 

 

Edited November 25, 2017 by Gavin Hannah

[bluearmy]

For some balançe, whilst the eps clusters are obviously showing mid Atlantic ridging end week 2 they are certainly not converging on one solution 

[shaky]

9 minutes ago, nick sussex said:

Latest from NOAA:

...PATTERN ASSESSMENT AND MODEL CHOICES...

INDIVIDUAL MODEL SOLUTIONS CONTINUE TO DIFFER BETWEEN EACH OTHER
AND FROM RUN TO RUN FOR IMPORTANT DETAILS, BUT ULTIMATELY THE
PATTERN EVOLUTION AND BEST APPROACH FOR REPRESENTING THE MOST
LIKELY SCENARIO FOR EACH DAY DURING THE EXTENDED PERIOD HAVE
CHANGED LITTLE OVER THE PAST 12-24 HOURS.

GUIDANCE AGREEMENT MAINTAINS RELATIVELY HIGH CONFIDENCE FOR THE
LARGEST SCALE ASPECTS OF THE FORECAST.  EXPECT A PROGRESSIVE WAVE
TRAIN TO BECOME ESTABLISHED ALL THE WAY FROM THE WESTERN PACIFIC
ACROSS NORTH AMERICA, THEN SLOWING AND SPLITTING AROUND A
PERSISTENT BLOCK OVER THE MIDDLE ATLANTIC OCEAN.

Hi nick could you post the 168 hour ukmo chart if possible!!thanks!!