Model Output Discussion - 26th December - 1st January

[marksp]

if your looking for cold, snow, and proper winter weather, truly dreadful charts on the 12z, this is light model watching back 3 to 5 years ago.

i would say its even worse becauce at least 3 to 5 years ago there was some eye candy to look at. At present there's nothing. Charts from 180 out show nothing of interest ( if you want snow and ice).

today has been dreadful, grey leaden skies all day, no sun, no blue sky, not even any clouds to marvel at, just dreay grey, with heavy persistent drizzel.

yesterday was the same althouh there was a couple of heavy showers with hail mixed in.

there seems to be a constant theme of South Westerlies alternating with the odd North Westerlery, ands lets face it if you have some alevation you might have some heavy wet snow.

theres not been much windscreen clearing of frost in these parts, and at least I have some allevation, believe me.

My worry is that when the strato and teleconnections come into play and start to effect the weather it could be March and April, when we really need stuff to happen from Jan to Feb.

plenty of weeks to go at present but this first half has definately been a long hard slog. I would like to see some signs in the next 10 to 15 days of some proper winter weather.

(sorry for the rant in the model thread but boy oh boy it ain't half been a long winter so far if your looking for snow and ice.)

anyway, an early Happy New Year to all and lets hope the next 10 days show some promise

:w00t:

[chionomaniac]

Please stay on topic

All who like the cold would love a good rant - just don't do it here!!

[Great Plum]

Well what do you know, the 12z GFS was a mild outlier (again!) in FI...

http://www.netweather.tv/index.cgi?action=charts;type=ens;sess=

This is getting boring now...

[johnholmes]

Well what do you know, the 12z GFS was a mild outlier (again!) in FI...

http://www.netweathe...;type=ens;sess=

This is getting boring now...

interesting as well Great Plum, much as the majority over the past week or two have shown, there is no marked cool down predicted either?

[Nick L]

Is there any particular reason why the GFS op is persistently a mild outlier? It will be interesting to see how it verifies compared to the actual conditions because if it is wide of the mark then I think questions will need asking about its reliability at the moment.

[johnholmes]

Is there any particular reason why the GFS op is persistently a mild outlier? It will be interesting to see how it verifies compared to the actual conditions because if it is wide of the mark then I think questions will need asking about its reliability at the moment.

I have no idea Nick but it does seem a bit odd for it to happen so regularly

[chionomaniac]

Is there any particular reason why the GFS op is persistently a mild outlier? It will be interesting to see how it verifies compared to the actual conditions because if it is wide of the mark then I think questions will need asking about its reliability at the moment.

It has only been consistently a mild outlier in final FI. Why? I certainly don't know Nick but would love a reasoned answer.

If the outlier was the other way round I certainly wouldn't expect it to occur so I believe that this is a case of watching the ensemble trend and not the operational.

[Robbie Garrett]

Please explain what a mild outlier, and for that fact what a cold outlier (if that exists) is?

[Grimsby Snow Lover]

Please explain what a mild outlier, and for that fact what a cold outlier (if that exists) is?

Its when a particular run, in this case the operational have little if any support from the other ensembles.

[Nick L]

It has only been consistently a mild outlier in final FI. Why? I certainly don't know Nick but would love a reasoned answer.

If the outlier was the other way round I certainly wouldn't expect it to occur so I believe that this is a case of watching the ensemble trend and not the operational.

Agreed. There's usually a consensus of "if FI is mild then it's bound to be correct", but I'm not so sure at the moment. The ensembles must be seeing something to consistently go against the operational. I wouldn't want to be a medium range forecaster at the moment, but I don't think the doom and gloom mood is entirely justified. Yes the op is a bit of a dogs dinner lately, but I can't recall it ever having such a lack of support from its own ensembles over such a long period of time.

[chionomaniac]

Please explain what a mild outlier, and for that fact what a cold outlier (if that exists) is?

An outlier occurs when the operational run is a distance away from the other ensemble runs for a significant period of time during the run. This can be either on the temperature or pressure ensembles and can be either increased or decreased from the mean.

The significance being here that an outlier cannot be trusted when compared to the rest of the ensembles.

The green operational run is the mild outlier for London at the end of the run here.

[Great Plum]

interesting as well Great Plum, much as the majority over the past week or two have shown, there is no marked cool down predicted either?

Indeed John, it's right on its own at the moment. There isn't a marked cool down by the ensembles but they are at least heading the right way... They have, for 4 or 5 days now, headed below the long term average on the 7th Jan...

[Cloud 10]

Please explain what a mild outlier, and for that fact what a cold outlier (if that exists) is?

Here is a more extreme example of a cold outlier saved from a couple of years back.

The green line represents the gfs operational run,and as can be seen is miles away from

the rest of the ensemble members.

I remember the gfs used to churn out some great FI charts for coldies,but that

was before it took an arrow to the knee!

[Duane S.]

And so it continues. None of the usual wavering about from the OP and the ens. They are trending cooler, the op remains steadfast mild and run after run the mildest run, some bordering on outliers. I'm sure it's happened plenty of times before but I don't remember it occuring run after run as consistently as this. Intriguing.

Imagine if perturbation 8 (its outcome below) had been the op....

[Cecil Hogmanay Melchett]

Looks like ECM is continuning with the flat zonal outlook with no sign of the PV wanting to give up the ghost and an intense anticyclone over the Azores.

I suspect the later stages may well show the high ridging towards the UK as per UKMO outlook.

Whilst its only fair peeps commenting on the out of kilter gfs op's i think many are ignoring the ecm is also promoting a very poor picture in terms of snow or cold potential.

Edited December 30, 2011 by happy days

[I remember Atlantic 252]

Is there any particular reason why the GFS op is persistently a mild outlier? It will be interesting to see how it verifies compared to the actual conditions because if it is wide of the mark then I think questions will need asking about its reliability at the moment.

isnt it because the 0perational is run at higher resolution, more accurate? meaning its mild for forseeable future, would operational be more accurate than all 20 ensemble members put together?

actually the last few operational runs been okay, showing much drier settled weather, high pressure been missing lately, bout time it returned, its not a pressure outlier

[Cloud 10]

The ECM12z has shifted tuesday's potential storm a bit further south,which would

mean the stronger winds further south and also an increased risk of snow for some

northern areas.

[mountain shadow]

Looks like ECM is continuning with the flat zonal outlook with no sign of the PV wanting to give up the ghost and an intense anticyclone over the Azores.

I suspect the later stages may well show the high ridging towards the UK as per UKMO outlook.

Whilst its only fair peeps commenting on the out of kilter gfs op's i think many are ignoring the ecm is also promoting a very poor picture in terms of snow or cold potential.

A bit early to call that, it;s only out to t+144

[feb1991blizzard]

isnt it because the 0perational is run at higher resolution, more accurate? meaning its mild for forseeable future, would operational be more accurate than all 20 ensemble members put together?

actually the last few operational runs been okay, showing much drier settled weather, high pressure been missing lately, bout time it returned, its not a pressure outlier

Only up to 192, which is when it becomes a mild outlier, as far as i know, the ensmebles are run at a higher resolution than the op post 192, i wouldnt ignore it completely though as other models, forecasting tools are pointing to milder than average, though i think that mild is a bit far fetched.

[Nick L]

I thought that the GFS op is run at a higher resolution to +192, but after that they are all run at the same res. This is where the main divergence is occurring so why it keeps happening is a strange one.

[mountain shadow]

Certainly looks promising if the PV will do one from Greenland.

http://www.wetterzentrale.de/pics/Recm1681.gif

[Robbie Garrett]

Its when a particular run, in this case the operational have little if any support from the other ensembles.

An outlier occurs when the operational run is a distance away from the other ensemble runs for a significant period of time during the run. This can be either on the temperature or pressure ensembles and can be either increased or decreased from the mean.

The significance being here that an outlier cannot be trusted when compared to the rest of the ensembles.

The green operational run is the mild outlier for London at the end of the run here.

Here is a more extreme example of a cold outlier saved from a couple of years back.

The green line represents the gfs operational run,and as can be seen is miles away from

the rest of the ensemble members.

I remember the gfs used to churn out some great FI charts for coldies,but that

was before it took an arrow to the knee!

Thanks guys, you learn something new everyday. So if all of the ensembles where to follow the operational down into a value, it's game on?

[bluearmy]

I thought that the GFS op is run at a higher resolution to +192, but after that they are all run at the same res. This is where the main divergence is occurring so why it keeps happening is a strange one.

i posted on this yesterday, i believe the op is still higher res than the gefs post T192 but by less than pre T192. the new parallel gefs ens are higher res post T192 but with less layers - 'you pays your money' etc

[Backtrack]

Thanks guys, you learn something new everyday. So if all of the ensembles where to follow the operational down into a value, it's game on?

The GFS is a mild outlier, so the operational would need to follow the ensembles.

Even then, it's not really game on. It's just a trend to cooler weather which could lead to something more promising as the month progresses.

Edited December 30, 2011 by Backtrack

[dixonoid]

looking at the ensembles at the moment, everything is reasonably settled with agreement from the models until about the 5/6th of January which is when Fi begins imo, so after this point is when the operational goes mild, and as good a guess as any of the spaghetti!