Model Output Discussion - cold spell to end Autumn

[weirpig]

1 minute ago, Frosty. said:

It does sound a bit cr*p for the south unfortunately as things stand. Perhaps becoming colder at times further north.

It's the very uncertain after Tuesday that's the tell for me. A few days yet I expect before all is settled 

Edited November 30, 2017 by weirpig

[mountain shadow]

1 hour ago, nick sussex said:

I

. However, in
evaluating mean ensemble guidance, it`s possible the plug is pulled
across the N Atlantic allowing zonal "escape" flow E by the weekend,
the downstream wall potentially having broken open.
 

I was enjoying that read and was hopeful of an amplified pattern until I read the bit above.

Looks like the Atlantic will be back in control sooner rather than later and we have to hope we can benefit from any amplification before the pattern flattens.

Will the GFS 12z follow the 6z or is it still playing catch up to the ECM?

[comet]

Why put so much emphasis on what the Met have to say. They have Been spouting cold for the first half of Dec for a week at least, now if it is going to be milder it does not fill you with confidence in what they have to say when they could not see this coming until it's right on their door step.

I said yesterday or the day before no one has a crystal ball. Let's see what this afternoon and this evening bring.

 

 

[festivalking]

So looking at the runs tonight the crucial point then is at 72hrs looking at that pesky shortwave over greenland?!

If anyone has the time or the inclination can someone post the area we are looking at and what we should and shouldn't see......thats if you are of the unhinged variety (coldie)

[Hocus Pocus]

4 minutes ago, comet said:

Why put so much emphasis on what the Met have to say. They have Been spouting cold for the first half of Dec for a week at least, now if it is going to be milder it does not fill you with confidence in what they have to say when they could not see this coming until it's right on their door step.

I said yesterday or the day before no one has a crystal ball. Let's see what this afternoon and this evening bring.

 

 

Off topic I know but to be fair the MetO haven’t been spouting anything, their forecasts have often highlighted the uncertainty going forward.

[Timmytour]

23 minutes ago, terrier said:

Well after reading the latest met update it seems they favour the ecm solution. With mild wet and windy further south. And colder further north. So it would seem the ecm could be on the money again. Looks like we are back to the realms of FI for a possible cold and wintry northerly. 

Met update from last week

 

Quote

 

UK Outlook for Tuesday 21 Nov 2017 to Thursday 30 Nov 2017:

To start it will often be cloudy with some outbreaks of heavy rain at times, possibly falling as snow over the hills of Scotland. It will remain rather breezy, with the risk of gales towards the north and west. Through the latter half of next week, the south of the UK should see spells of cloudy and wet weather, with temperatures generally around or above average. Meanwhile the north is likely to be drier, brighter, but colder with some frosty mornings. Towards the end of November confidence is low, but rather mixed conditions of cloud and rain (with snow in northern parts) is likely, interspersed with some drier and brighter interludes. Temperatures are likely to stay around average or just below.

 

Looking out my office window in London and seeing snow falling made me think that Frosty's summing up of what he saw from the models at the time for the week ahead was a lot closer to the mark! 

[Derecho]

9 minutes ago, festivalking said:

So looking at the runs tonight the crucial point then is at 72hrs looking at that pesky shortwave over greenland?!

If anyone has the time or the inclination can someone post the area we are looking at and what we should and shouldn't see......thats if you are of the unhinged variety (coldie)

So this is the same run just 15 hours later, that little shortwave I highlighted has cut off the link of the three key areas of high pressure:

- To the west of the UK
- Over Greenland
- Over the far NE of Canada

The cutting off of this link introduces some colder air to the West of Greenland, the high to the west of the UK is no longer pumping warm SE winds to this region. The colder air means more disturbances form and then the high sinks.

[snowking]

6 hours ago, snowking said:

Something to be a little wary of out in the Pacific at the moment is this:

If this typhoon east of the Philippines does turn out to be a reality then the forecast recurvature will create all kinds of varying solutions hemispherically with consequences for the downstream longwave setup

This is not to say this changes our fortunes in any way, but just something to be wary of in day 7+ modelling at present 

A great image from Michael Ventrice over on twitter from the GEM ensembles to show just how varied the forecast track on this is right now:

Very different effects on the downstream pattern depending on whether this slams straight into the Philippines or recurves back into the Pacific (the latter of those would be preferable both for the people of the Philippines and for our selfish amplified hopes)

[karlos1983]

updated AO & NAO forecast.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/

[Paul_1978]

1 hour ago, Hocus Pocus said:

Off topic I know but to be fair the MetO haven’t been spouting anything, their forecasts have often highlighted the uncertainty going forward.

Indeed. 

We are in danger of straying, but @terrier didn't mention this key paragraph from the extended outlook. 

Confidence is currently low for which pattern will be most likely prevail at this stage as it currently looks to be a constant battle between weather systems arriving from the south and west against the push of colder air from the north. This suggests temperatures will generally be below average with some milder interludes.

Nevertheless, model watching in coming weeks sure to be as exciting as it is frustrating! Can't wait!

 

[Frosty.]

Just for fun, here is the Gfs 6z snowmagheddon wintry heavenly run since my last few posts were a bit negative..even the woodshed would get a covering..I would of course love this to verify!..in the meantime, enjoy the snow showers across eastern and later central parts of England through the rest of today and tonight.????

[Tom Jarvis]

Icon is rolling out and some small changes at t42 with the higher slightly stronger and the low in the Atlantic more flabby 

[Methuselah]

Right then, it's that time again...

Will our trend-friendly GFS12Z finally deliver the goods? Or will winter be put on-hold for the umpteenth time-being?

I think we might like to see an Arctic blast at around T+120ish. Anywho - here's hoping...

Prozac on standby...

[Robbie Garrett]

Been ages since I've posted a detailed thought on the model process. Based on the 06z ensemble, I wouldn't trust anything past the 3rd-5th of Dec.  It's all over the place, so looking past the 5th is pointless.

 

 

The key timeframe is 120hrs onwards, to see how much warmth from the Gulf gets pushed up over Greenland.  Once we have that in place, potential Wed-Thursday next week onwards for some low lying levels.  IMHO, the zonal default as per usual post that Greenland High forming is no mans land. Let's wait and see. ^ It's volatile.

[weirpig]

2 minutes ago, Ed Stone said:

Right then, it's that time again...

Will our trend-friendly GFS12Z finally deliver the goods? Or will winter be put on-hold for the umpteenth time-being?

I think we might like to see an Arctic blast at around T+120ish. Anywho - here's hoping...

Prozac on standby...

Yep  Pete eyes down lets see the trend from the 6z continue on the 12z.    im also keeping an eye on the ICON rolling out now.  The Icon!  times really are desperate. 

[karlos1983]

Just now, weirpig said:

Yep  Pete eyes down lets see the trend from the 6z continue on the 12z.    im also keeping an eye on the ICON rolling out now.  The Icon!  times really are desperate. 

separately, Worth noting the Icon slammed the Tropical Cyclone straight into the Philippines on it's earlier run, whereas the GFS takes it straight out into the Pacific south of Japan. 

Anyone know how well this model performs? or is it just a gap filler whilst we wait for the big dogs to roll out.

[bluearmy]

1 minute ago, karlos1983 said:

separately, Worth noting the Icon slammed the Tropical Cyclone straight into the Philippines on it's earlier run, whereas the GFS takes it straight out into the Pacific south of Japan. 

Anyone know how well this model performs? or is it just a gap filler whilst we wait for the big dogs to roll out.

Depends how cold the run is !!

it verifies below the big three but it’s generally not too far away from the general direction of travel of ecm later

[weirpig]

1 minute ago, karlos1983 said:

separately, Worth noting the Icon slammed the Tropical Cyclone straight into the Philippines on it's earlier run, whereas the GFS takes it straight out into the Pacific south of Japan. 

Anyone know how well this model performs? or is it just a gap filler whilst we wait for the big dogs to roll out.

To be Honest  I really have no idea  took no notice until a few days ago.   Update its more amplified  than its last run!  i expect its on par with the Bom etc

[captaincroc]

3 minutes ago, weirpig said:

To be Honest  I really have no idea  took no notice until a few days ago.   Update its more amplified  than its last run!  i expect its on par with the Bom etc

Even if it's the dogs dinner any positive movements do bode well for later, so if it is more amplified then that is a bonus, be it small. 

Edited November 30, 2017 by captaincroc

[Yarmy]

4 minutes ago, karlos1983 said:

separately, Worth noting the Icon slammed the Tropical Cyclone straight into the Philippines on it's earlier run, whereas the GFS takes it straight out into the Pacific south of Japan. 

Anyone know how well this model performs? or is it just a gap filler whilst we wait for the big dogs to roll out.

It's the new version of the German GME model. I don't have any stats, so I've no idea how it performs. On the subject of verification, the GFS is now lagging in 4th behind the Canadian GEM.

At day 5:

and day 6:

 

 

 

[Methuselah]

4 minutes ago, weirpig said:

To be Honest  I really have no idea  took no notice until a few days ago.   Update its more amplified  than its last run!  i expect its on par with the Bom etc

Tonight's BOM is going to go off with a bang...Reverse zonality, anyone?

[East_England_Stormchaser91]

Relating to the typhoon in the Pacific, wouldn't that help out chances of blocking going by the theory of dumping warmer air into the pole and then translating into blocking further down the line? 

Also with a potent cold blast down to right near the Gulf of Mexico, surely that would aid WAA up the eastern seaboard, which the models have now been keen on showing. Watching a programme on the notorious 1962/63 winter, they mentioned how cold and bad the winter was in the GOM, so I'm thinking this may not be a bad thing.

 

[karlos1983]

1 minute ago, Yarmy said:

It's the new version of the German GME model. I don't have any stats, so I've no idea how it performs. On the subject of verification, the GFS is now lagging in 4th behind the Canadian GEM.

At day 5:

 

that's not very reassuring  given this mornings output

[chrisbell-nottheweatherman]

21 minutes ago, Robbie Garrett said:

Been ages since I've posted a detailed thought on the model process. Based on the 06z ensemble, I wouldn't trust anything past the 3rd-5th of Dec.  It's all over the place, so looking past the 5th is pointless.

 

 

The key timeframe is 120hrs onwards, to see how much warmth from the Gulf gets pushed up over Greenland.  Once we have that in place, potential Wed-Thursday next week onwards for some low lying levels.  IMHO, the zonal default as per usual post that Greenland High forming is no mans land. Let's wait and see. ^ It's volatile.

That analysis seems very valid to me; as someone who can't predict the movement of a shortwave two model frames ahead, I stick to my strengths and use my scientific training to take the approach you've use here - where does entropy cause divergence of ensemble members and the op. and control runs?  By so doing I avoid all the emotional torment many on here seem to endure by putting their faith in set-ups which are deep into F.I.  At present, I'm not that interested in anything past the 6th as it's evident from these line graphs that uncertainty is rampant beyond that stage.  In fact, the only thing I do check past that point of inter-run divergence is to check where the ensemble mean and the operational and control runs are relative to each other to give me an idea of whether they're obvious outliers.

Edited November 30, 2017 by chrisbell-nottheweatherman

[Yarmy]

4 minutes ago, karlos1983 said:

that's not very reassuring  given this mornings output

I don't know why the put so much time and resources into generating 4 runs a day. Perhaps concentrating effort on a 0z and 12z would help. They've thrown a lot of money into it over the past few years, but it doesn't appear to be improving.