Model Output Discussion - 8th - 14th January

[gottolovethisweather]

Why do some posters find it so hard to understand why people aren't discussing next week? Well maybe it's because High Pressure will be residing near to our shores and potentially as time progresses, it'll be right over us. Personally I don't mind HP cells being nearby at first, as is often the case, positioned correctly, they will lead to something much better down the line for coldies.

Of course, there is a risk that things won't go as planned during the period in question, but it is a must that we see some "building blocks" come mid January IMHO. Stratospherically we're getting there, trendwise we're getting there but only time will tell how good it gets. I would personally also like to see some cold plunges into europe too which enhance our chances of an cold easterly in the not too distant future.

Ok, some charts to back up my predictions as to why THINGS ARE GETTING BETTER for coldies.

Comparing corresponding 06z NH runs to those from two days ago. OK, most definitely in FI here.

However, now quite a bit closer to home, being potentially within the realiable.

Finally the temperature trends for the forseeable, note the persistent clustering of cooler temperatures from around the 15th January onwards, in line with NH action. THIS APPLIES TO BERKSHIRE ONLY but there is an undeniable downward trend in my opinion, run after run!

Will all these pieces of the puzzle start to fit together? Let's hope so.

Kind Regards

gottolovethisweather

Edited January 8, 2012 by gottolovethisweather

[SMU]

So basically you're saying the 06z is rubbish?

Well people say the 18z is rubbish as this is the 'pub run'

So that leaves us with the 12z and the 00z. I just don't believe that we can simply write off 50% of the data that's input into the GFS.

All 4 GFS runs have different starting data-

the 06z has the worst track record of the whole 4 suites & this is just day 5- it will only get worse out to 8,9,10

At day 5 for the ATLANTIC modelling the 06z is a DOGS DINNER- you are looking for the lowest score-

http://www.emc.ncep.noaa.gov/gmb/STATS/html4x/rmsmereg500.html

NOTE

the NH chart on the left the best run is 00z, but if you drill down to the atlantic you will see the 12z handles the pattern the best-

So in its own cacoon the GFS 00z & 12z are the best,- but the 12z handles the atlantic pattern 'generally' the best-

now if the GFS 00z is the BEST on the northern Hemisphere 20N-80N then so how does the 00Z stack up at 5 days V the rest-

http://www.emc.ncep.noaa.gov/gmb/STATS/html/rmsz56.html

Since December 11th to the 7th jan its been a consistent 3rd- & this week is in LAST PLACE-

whats the top model the ECM ( not sure if 12z or 00z)

So you can safely note that if the GFS 00z is currently last at day 5 & its the best GFS there is then the 06z & its even worse ensemble suite are about as accurate as the WMC model which doesnt even appear on those statistics because its usless-

In summary-

the 06z & the pub run sadly can burn in model hell as they are pisch..... just like the GFS ( most occasions)-

S

[Isolated Frost]

Anyway... as I have said before, it IS good to look at all output, I tend to think if you are going to accompany ANY NWP with the background details (tech thread and strat thread for more of that), it would be the ECM. I have taken note of the GFS, but I have been following the ECM output especially, I think it consistently performs above anything else and have more confidence in that than in the GFS per se.

Yesterday's 12z +192 on the ECM... if we can bring that trigger low, high alignment and immense cold pool up to +168 I believe the possibility of a cold spell around mid-january has widened substantially. Take that along with the extra stratospheric warming which should generally finish off the PV, then I think reloads galore in mid-late january.

Edited January 8, 2012 by Paul
Removed off topic comments

[kumquat]

IF the Strato warming occurs and disrupts the PV then the Jet will slow down, if not totally fragment. I wonder if there will be a delayed reaction to modelling this on the various model suites.

[ChartViewer]

Step back to cold lovers today after last nights optimism......06GFS/00z ECM show how you can get hung up over 1 or 2 runs...especially at T180.............However the chart posted of the artic high splitting us right down the middle was very impressive as it is very rare to see. Although that could send cold down into Greece Turkey etc.

Still lots to play for after last nights and this mornings models.....However caveats are UKMO T144 and UKMET outlook doesnt really inspire for coldies.

Regards

Edited January 8, 2012 by ChartViewer

[Matty M]

Interesting to see so many members on here at such a lull in model output.

But highlighting the emergence of the GEM as a possible model to follow.

The Canadian model has performed well recently particularly with recent storms etc.

It was first to pick up on the potential Scandy High pressure scenario, and the fact that its

0z backs the ECM 0z is very interesting.

The hope is that once we get these pieces in place by T144hrs that the strat warming will continue to drip feed

into the troposphere and model output, weakening the PV and jet and reducing the force of the Jet on top

of any High feature to our northeast, increasing the likelihood of cold and snow.

[Osbourne One-Nil]

Please remember, there are two separate threads; this one for model output discussion and this one, for general model comments, moaning etc.

[The Northern Ramper]

I think the issue is here, that some members are expecting a repeat of last December. This type of reliance on the models bringing up this type of scenario will inevitably lead to disappointment.

That explains alot in the nature of defeatest posts.

I someone who has no allegiances to the outcome (ie I don't care if it gets cold or mild, that doesn't interest me), I can see potential for cold judging by the models, but not severe cold, but calls for disappointing runs, are a little wayward too, as that is not really the case.

It actually is a case of taking the mid-point.

I take your point, the problem about expectations being some knowledgeable posters keep mentioning historic months in years in realtion to what the potential could be.

Anyhow enjoying the current evolution, i fully expect the models to start throwing better charts out once they get to grips with the stratospheric changes.

[nick sussex]

Not long to wait now before the next episode of the easterly soap opera.

Given theres good agreement for the Arctic high and a lobe of higher pressure developing towards Svalbard then it's really now how amplified the pattern will be upstream.

The key timeframe is between 120 and 144hrs and the orientation of that approaching low west of Greenland, the further west and south this is the better and you want it orientated at least north/south.

If its aligned ne/sw thats not good news so you're looking for either a negatively or neutral tilted low, a positively tilted one will likely lead to less of a stronger ridge ahead of it and energy will topple too far east.

If you get the right amplification around 120-144hrs then some form of easterly would have a good chance.

Regardless of what the GFS and ECM shows you must have the UKMO on side.

[OldMetMan]

Hi OMM

You asked/mentioned why models are now 'suddenly' picked this view/trend up, I have my views and indeed RJS predicted this....we're not there yet but huge improvement, but I go back to posts saying that the PV will be really hard to breakdown. Well if there are forces/influences timed not to break it down until approaching mid Jan, and we see it collapsing before our eye...is it really hard to break down? Or were there just no 'forces' at all into place to make any real atttempt until now and it never really was due to change until now? What I'm saying is take RJS theory, if it doesn't break down, move , split as aroungd his timings or of course GPs method then maybe yes its hard to breakdown.

Hi BFTP, thanks for that.

Today's models are even more interesting, GFS trying to return to zonality, the ECM sticking to its guns and setting up a cold blocking pattern. It's a little hard to fathom the differences, other than repeating the regular accusation that GFS defaults to a zonal flow.

I see what you are saying regarding the PV. The jet position and strength is clearly going to be critical if the model trend is to happen.

I've got a 200mb hemispheric chart that shows the current situation very nicely:

I was discussing jet locations yesterday and I think the current situation does favour a breakdown of the strong polar jet.

First, we have a split flow to our west. We need that at least if any easterly has any chance of developing.The most energy seems to be in the Pacific jet right now whilst the sub-tropical jet to our south is weakening and heading off E into S Europe and Asia. At the same time new energy is developing from the Caribbean and heading out into the Atlantic as well as the SE Pacific heading for Mexico and the Gulf.

Looking at the polar jet from the US to here, this has weakened quite a lot from what we have seen lately.

What I am trying to say in my roundabout way is that it looks to me as if we are seeing energy transference southwards with the main jet pushing eastwards to our south. The GFS is re-introducing the strong jet right at us again before any blocking can take hold and this doesn't look right given the current jet positioning. The ECM on the other hand looks more likely with a weaker polar jet to our NW.

Jet postions apart, with the current HP over us for a few days, the model development of a low plunging SE over E Europe and pulling in the extremely cold air from Siberia is a very reasonable prediction, one I have seen on many past occasions. With the very cold air comes the opportunity for intense HP to develop.

So, I think it all comes back to what I said at the beginning; jet position and strength and based on what I see in the current positioning, I would favour a block developing.

Of course, my reasoning could all be spurious! As always, I am happy to be corrected by those more knowledgeable about these technicalities!

[johnholmes]

The utterly realistic view is that other than turning generally country wide less mild and very probably more settled for southern areas, deep cold is not certain. As I tried to show in the pdf the longer term charts are far from clear as to the outcome. The Stratosphere has not YET gone the way its needed to go to introduce a higher proability of blocking. Until that happens then any prolonged cold is highly unlikely. That is not to say that cold (By Met O definition) will not occur over a few days from time to time. But prolonged cold does seem to need what the Stratosphere thread is all about and very well explained by chio and Co. For those new to all this its well worth reading through the thread much of it is written in an easily understood manner and there are explanations along the way.

Be realistic, don't expect another December 2010 and then if you are a cold-snow lover remember there is still 23+29 days (if my maths is right) of winter left.

[summer blizzard]

Interesting to see so many members on here at such a lull in model output.

But highlighting the emergence of the GEM as a possible model to follow.

The Canadian model has performed well recently particularly with recent storms etc.

It was first to pick up on the potential Scandy High pressure scenario, and the fact that its

0z backs the ECM 0z is very interesting.

The hope is that once we get these pieces in place by T144hrs that the strat warming will continue to drip feed

into the troposphere and model output, weakening the PV and jet and reducing the force of the Jet on top

of any High feature to our northeast, increasing the likelihood of cold and snow.

GEM is overlooked a lot.

At day 5 it is actually quite close to the GFS in verification (or was last summer) in 4th place however i have followed it the past two Autumns at day 10 and it is not far off the ECWMF in 2nd place, well ahead of the GFS at that timeframe.

[winterof79]

Am i the only person not looking for an easterly on the 12z output?I am just happy to see the evolution of the ever colder senario come closer into the more reliable time frame,be it from the North/North west or whatever.The overnight output gave us numerous chances of snowfall.long may it continue.

[Zenarcher]

My take on the weather models this morning,

GFS

Between 72 hours to 120 hours it has the low moving along the Atlantic ridge in a similar position to many of the other models and places it to the South East of Greenland this positioning agrees with the GEM and NOGAPS but not with the UKMO and ECM. At 144 hours it is keen like all the models to bring down the high pressure from the North but looking out to the Atlantic the GFS brings in a strong low which creates problems for us at 168 hours. No other models suggest a low this deep and we all know the GFS likes to overdo them. However the other models do show a low in that area but with higher pressure over the Atlantic stopping this low from causing problems later.

ECM

Between 72 hours to 120 hours it has the low moving along the Atlantic ridge and places the low just South off Greenland. Only the UKMO agrees with this as the other models have it slightly further North. From 144 hours to 168 hours the ECM brings in that high pressure into the Atlantic and pretty much kills off PV and this then allows the high pressure to move in from the North over the UK. The GEM model also shows something like this.

UKMO

This model is hard to compare to the others but it does seem to support the ECM up to 120 hours and at 144 hours it isn't really keen to let high pressure build up in the Atlantic.

However there are improvements on the UKMO over the last 24 hours as shown below,

It starts to agree more with the ECM and other models at 120 hours.

GEM

The model that picked this 24 hours ago and a day on is still keen on giving us a pattern change. In fact its looking better than what it did 24 hours ago. The model pretty much shows the same as the ECM so good solid agreement between these two at the moment.

NOGAPS

A pretty bad run showing something similar to the GFS with the high pressure struggling and pretty much failing to reach us as that low out in the Atlantic moves in and ruins any chances. However there may be light at the end of the tunnel for NOGAPS as its 06z run this morning changed things slightly its pushed the low moving in that causes problems further North as it notices high pressure is building in the Atlantic something the ECM and GEM are showing. It also made the high pressure heading our way in the north a lot higher and has more of a chance reaching us than before.

Overall some disagreement from 144 hours onward. With the ECM and GEM showing the best agreement beyond that time range. The UKMO has started to agree at 120 hours as well. The GFS and NOGAPS don't like the idea at the moment of high pressure building in the Atlantic to kill of PV later however this mornings NOGAPS run has decided to change things for the better and agree more with the ECM and GEM. Perhaps the NOGAPS and GFS may be playing the catch up game at the moment.

[johnholmes]

a lot of thought and work their W-thanks for that analysis

[Matty M]

It will be of interest this evening to see if the GFS 12z can build on last nights GFS 12z run.

It is very important to compare like with like similarly tonights 12z ECM with last nights 12z ECM, this is how

you can map whether a trend is gathering momentum or not.

If we see charts similar to last nights on the GFS and ECM it will be a step forward in the right direction for cold weather supporters.

Early signs on the 12z run point to a bumper run but i am a gambler!

[Summer Sun]

Looking good so far cold air slowing getting into more of Eastern Europe

Could be a good run tonight

[dixonoid]

Looks like the high pressure is starting to ridge north earlier on this run.

[tinybill]

all i can say is than end of jan 21 looks interesting at the moment!!!

[Harsh Climate]

all i can say is than end of jan 21 looks interesting at the moment!!!

I bet in 20 minutes time, that will have completley disappeared

[Thundery wintry showers]

If we are to get a shot at a few days of "easterly" weather (and yes, there is a cold enough airmass there on the ECM to bring snow showers over the North Sea) we need to see a lot made of the gap between the Scandinavian and Icelandic lows at around T+120-144. This would allow a build of pressure in between the gap to allow an easterly incursion in, though as John's post suggested the current state of the stratosphere would point towards any such easterly being short-lived.

My current feeling though is that the easterly is odds-against, particularly as the ECM ensemble mean doesn't show much support for its operational run. However, the general consensus is colder and probably a bit less settled as we head into the 5-7 day timeframe.

Before that, most of us look set to have a cloudy mild week with drizzle in the west, but note that the GFS 12Z indicates a clearer slot moving in on Monday night, which may lead to a slight frost in many areas. In general southern parts of England are most likely to see a few breaks in the cloud sheet, which may become rather more extensive by the end of the week as the tropical maritime airflow is cut off.

[pinball wizard]

all i can say is than end of jan 21 looks interesting at the moment!!!

There is more chance of Ipswich going the rest of the season without conceding a

goal than there is of that chart verifying.

[sebastiaan1973]

I think GFS12 is a failure. At 114 we can clearly see a zonal and not a meridional development in the East of America.

[Matty M]

@ T132 on the GFS we just need the Arctic high to take the initiative and strike southwards. Believe and you will win.

[Isolated Frost]

I think GFS12 is a failure. At 114 we can clearly see a zonal and not a meridional development in the East of America.

Indeed- the hi-res of this GFS should be similar to the 6z. Note 'should be'... there is potentially much better developments in ne europe.. but it's best not to take every nwp run as gospel right now.