Model output discussions pm 31/12/15

[swilliam]

Shortwave alert around Iceland - holding back the colder air.

[karlos1983]

Nice change from the GFS 06z to 12z

06z

12z 

Some decent WAA pumping up to the west of Greenland

 

[TSNWK]

3 minutes ago, swilliam said:

Shortwave alert around Iceland - holding back the colder air.

I wonder if they might drop down within the flow though and gift the north with some whiteness.. 

[Climate Man]

2 minutes ago, swilliam said:

Shortwave alert around Iceland - holding back the colder air.

Nothing wrong with that as may introduce a snow opportunity in it's own right and colder air does arrive. Also better heights Atlantic and Greenland

[Mucka]

2 minutes ago, swilliam said:

Shortwave alert around Iceland - holding back the colder air.

I think GFS throws up the worse possible scenario from 168 to 192 with all the energy going in the wrong directions and appearing in the wrong places so I am happy with the run out to the reliable.

[mountain shadow]

4 hours ago, swilliam said:

Shortwave alert around Iceland - holding back the colder air.

Negatively tilted though. May slide into the colder air.

[West is Best]

It's been threatening this kind of evolution for days. It doesn't mean we're on course, nor anything like it, but at least we can genuinely say it hasn't come out of the blue. Game's still on.

[Mucka]

UKMO looks very good to me @144, full of potential.

 

GEM cut off Greenland high, could just do with being a little further East.

Edited January 4, 2016 by Mucka

[radiohead]

GEM

[karlos1983]

All gone a bit messy.

 

Looks like the heights over Greenland have gone and the PV is rebuilding in later stages.

[TSNWK]

6 minutes ago, Mucka said:

UKMO looks very good to me @144, full of potential.

Does look nice.. And if my learnings are correct, then it is certainly unusual to see high pressure over Newfoundland instead of the next low pressure system lining us up. I also notice that there is low pressure area over the north eastern states, which might  prove helpful towards pumping up the Newfoundland high a little more.. So far I would the 12z suite has been postive for coldies.

Edited January 4, 2016 by TSNWK

[warrenb]

GFS revert to type.I look at the GFS as a rubber band, when a change is in the offing, it will always try to revert to standard fair

[TSNWK]

6 minutes ago, radiohead said:

GEM

Does look ok to me.. And with that vortex over north eastern Canada with its negative tilt, surely that can only help pump up the Greenland high

[Mucka]

5 minutes ago, karlos1983 said:

All gone a bit messy.

 

Looks like the heights over Greenland have gone and the PV is rebuilding in later stages.

This run is like a reverse of what usually happens in the search for cold. Normally the signal is tentative and we have to search around for runs where everything goes just right to get some eye candy - in this case everything goes just wrong to avoid eye candy. For that reason I would give much more weight to the positives out to 168 than the negatives thereafter. I think the ensembles and 10 day mean anomalies will be telling in that regard but we will see.

Edited January 4, 2016 by Mucka

[mountain shadow]

Very strange GFS.  Everything looked right and just went err wrong.

 

[ALL ABOARD]

Can you imagine that would just be our luckkk......

 

Cold spreading into africa?

[BLAST FROM THE PAST]

The 12z looks better on face of it compared to 06z but it isn't.  Block will collapse as that SW near Iceland puts spanner in works.

I get this feeling that the ridge is a temporary one and won't succeed to dig in and hold this time round.  This isn't to say it won't but just my take on it.  If it can get a propoer foot in then it could get very interesting cold wise.

 

BFTP

Edited January 4, 2016 by BLAST FROM THE PAST

[booferking]

We just always seem to be so unlucky previous runs the Greenland high would not build strong enough to meet the Arctic high now it seems the Arctic high is not strong enough to help the Greenland high you can,t write this stuff still plenty of time for improvements 

Edited January 4, 2016 by booferking

[tight isobar]

The gfs 12z'

Starts ok sniffs at cross polar positive flow..then quickly stamps on the idea!

Gem, pick of the 12zbunch (thus far)! With a partial greenland block' extending to a more pronounced one.

Its typical model mismanagement via gfs imo...

And plenty to be watching for on a northern hemispherical scale.

Be watching this evening ecm with KEEN interest! 

[ukpaul]

GFS is having a nightmare trying to model the US in the next week or so; there is no consistency at all. Because of that the building blocks are having so many contrasting things thrown at them that eventually one of them sticks.

Until that pattern is settled then anything beyond 144h is going to be on shifting sands.

[Captain Shortwave]

A real mixed bag of results in terms of developments after 5 days or so. Lets look at the northern hemisphere at six days out.

GFS

High pressure over the Arctic with a ridge over Western Canada and a weaker one over Newfoundland.

UKMO

This establishes a cross polar flow between Alaska and central Russia, the GFS doesn't even get close to the amount of ridging on the Russian side of the pole as the UKMO does.

GEM

Ridging on both the Russian and Western Canadian sectors is weaker, but we get a better Atlantic ridge supported by low heights beneath the high in the Atlantic. This low does show up on the other three in slightly different locations.

The GFS produces a very messy toppler event, whilst the GEM develops the Greenland high but the pattern sets up too far west, classic west based -NAO, this aided by low heights becoming cut-off over the eastern parts of the USA. 

This pattern looks rather complex to get all the pieces to fit together for cold over the UK, but we have enough disagreement at 5 days out, let alone whether we get the end cold spell or not several days later. At this point for me the key is to avoid at all costs creating a scenario which can regenerate that lobe over Canada (GFS does this), at the same time you need to ridge in the right place to allow cold air to plunge over Europe and the UK.

Edited January 4, 2016 by Captain Shortwave

[Stormeh]

The 12z GFS is bad but no point worrying about it as it will all change again by the 18z. All the models are struggling, so no point looking after 144.

[nick sussex]

Well the GFS backtracks towards the more amplified solution and looks good for a time before going downhill. Regardless of the later timeframes we do need to see that more amplified upstream pattern because this at least gives a chance for some WAA towards Greenland. The UKMO is more interesting especially as it takes the jet further south.

 

[Radiating Dendrite]

Let's just hope this is not a repeat of what happened last week. The ECM and UKMO were both optimistic and then back tracked to more of a blended version of what the GFS had showed.

The GFS gets criticised for showing messy scenarios when the Euros can often be cleaner but sometimes they are too clean and the ECM has had a tendency to over amplify things the last 18 months. 

[Mucka]

Disturbance in the force.

 

Looking at GFS ensembles out to 192, and predictions for the NH profile, I think we will be very unfortunate not to get something out of this one way or another. (At least first proper cold snap/spell of the Winter)

Edited January 4, 2016 by Mucka