Model Output Discussion - Early November Onwards

[ITSY]

GFS 12Z shows Easterly coolness at the end of the low res and beginning of FI only for...the Atlantic to gain strength with HP coming in from the mid Atlantic. Don't buy the outcome but certainly suggestive of what I think represents a misinterpretation of the current output in that: it will briefly get more seasonal and perhaps skirt with cold for a day or two somewhere, but ultimately it will be minor and return to mild November weather very quickly

[Snowmad79]

The UKMO at 144hrs is the most interesting output for weeks but there are some big differences between it and the GFS regarding the amplitude of that upstream trough.

Do mean the LP situated over newfoundland where on the UKMO it doesn't have the break off low to its south, with a better track and a much better drag on warm air which in turn could beef up HP over Greenland ?. This is what S.M was refering to at 168hrs on Fridays output no ?

[chionomaniac]

Hi Guys,

I am puzzled re.your exchanges about an "existing" -NAO .

I have run through the 12z GFS and out to T240 i cannot see a -NAO pattern.

I do see a lot of energy still north of 60degrees coming off the Eastern seaboard with quite a lot of mid-latitude high pressure in the Atlantic so i cannot see this -NAO, west based or otherwise.

Here at T144 is typical of this run

Certainly what we do have is "warm" euro high persisting for a while yet and a weakening atlantic trough keeping us in a mild southerly type flow.

Forgive me if i have missed something in which case i am sure you can enlighten me,

Regards,Phil

Hi Phil,

This chart here:

It may not look classical but would give a negative NAO. There have been a number like this over recent days which is why the NAO ensembles have looked to dip negative. Technically negative but a 'false negative' in terms of what coldies are looking for.

Edited November 6, 2011 by chionomaniac

[nick sussex]

Do mean the LP situated over newfoundland where on the UKMO it doesn't have the break off low to its south, with a better track and a much better drag on warm air which in turn could beef up HP over Greenland ?. This is what S.M was refering to at 168hrs on Fridays output no ?

Yes thats crucial for pressure rises over Greenland, lets hope the ECM backs the UKMO this evening.

The ECM looks more like the UKMO at 120hrs still waiting for the 144hrs.

Overall the ECM and UKMO are similar in terms of overall pattern. The GFS is much flatter with the jet, the actual differences begin to show up as early as 96hrs with the troughing near the UK and upstream in the USA.

So we'll have to see which model has called this correctly, however for the GFS to be right the UKMO and ECM would both have to be wrong from as early 96hrs which would be very unlikely.

Edited November 6, 2011 by nick sussex

[SMU]

http://www.meteociel.fr/modeles/ecmwf/run/ECH1-168.GIF?06-0

for reference this was the crux of my post the other night- Its nice to see the Euros now developing this pattern-

It all depends if the Euro high gets sucked up into greenland-

I think the models have been WOEFUL lately

S

[Frosty.]

An interesting Gfs 12z after the week ahead with the chance of a colder outflow from eastern europe replacing the mega mild breezes from southern europe BUT it will be turning very mild again during the next 5-7 days, up to 16c by wednesday and potentially up to 17-19c by fri/sat so the ridiculously mild autumn goes on and on for now but then it may turn colder, not cold enough for anything wintry but certainly it should begin to feel like november at least. The charts later in FI begin to get messy with the atlantic threatening to take charge but then giving up with pressure rising but less mild than the next week is going to be.

[nick sussex]

Not a bad ECM this evening with the high edging west and some colder temps likely, also a good shot of much colder air into Scandi and eastern Europe ready to be transported further west at a later date!

The GFS was ditched this morning by NOAA , they didn't like it because it was too progressive, still waiting for the latest update but given the rest of the output so far you'd have to think it's wrong.

If you take one major positive from this evenings output it's where the PV is, patience still needed but there is light at the end of the mild tunnel.

[snowfall09]

This euro high has got to give sometime, in the past have we ever had a euro high giving us very mild temps??? if so what happened next??

[johnholmes]

Hi Guys,

I am puzzled re.your exchanges about an "existing" -NAO .

I have run through the 12z GFS and out to T240 i cannot see a -NAO pattern.

I do see a lot of energy still north of 60degrees coming off the Eastern seaboard with quite a lot of mid-latitude high pressure in the Atlantic so i cannot see this -NAO, west based or otherwise.

Here at T144 is typical of this run

Certainly what we do have is "warm" euro high persisting for a while yet and a weakening atlantic trough keeping us in a mild southerly type flow.

Forgive me if i have missed something in which case i am sure you can enlighten me,

Regards,Phil

I'm afraid Phil that some are being just a touch easy shall we say with some meteorological terms and what a term actually means rather than analysing charts a touch more carefully. Always also with the proviso its one run..

Its looking like being a very very long winter in terms of reading the model thread judging by the hunting for cold on every run that is already occurring.

Edited November 6, 2011 by johnholmes

[phil nw.]

Hi Phil,

This chart here:

It may not look classical but would give a negative NAO. There have been a number like this over recent days which is why the NAO ensembles have looked to dip negative. Technically negative but a 'false negative' in terms of what coldies are looking for.

Mmm,I always regard a -NAO to be when we have Upper Heights north of the Polar front at High latitudes Chiono, with energy much more into the Southern Jet with low pressure towards the Azores.

On that chart it looks at best neutral with those hts around mid-latitude.

I don`t wish to nickpick for the sake of it mate but i think it`s important when we use these terms that we use the classic meanings otherwise newer members can get confused.

Having said all that i don`t think we are too far away where we could evolve into a -NAO- but not this week.

Anyway thanks for your reply.

[johnholmes]

Mmm,I always regard a -NAO to be when we have Upper Heights north of the Polar front at High latitudes Chiono, with energy much more into the Southern Jet with low pressure towards the Azores.

On that chart it looks at best neutral with those hts around mid-latitude.

I don`t wish to nickpick for the sake of it mate but i think it`s important when we use these terms that we use the classic meanings otherwise newer members can get confused.

Having said all that i don`t think we are too far away where we could evolve into a -NAO- but not this week.

Anyway thanks for your reply.

see my post above Phil could not agree more with your thoughts

[Frosty.]

Not a bad ECM this evening with the high edging west and some colder temps likely, also a good shot of much colder air into Scandi and eastern Europe ready to be transported further west at a later date! The GFS was ditched this morning by NOAA , they didn't like it because it was too progressive, still waiting for the latest update but given the rest of the output so far you'd have to think it's wrong. If you take one major positive from this evenings output it's where the PV is, patience still needed but there is light at the end of the mild tunnel.

Does that mean the Gfs 12z will also be ditched? the gfs 12z looks nothing like the 00z. I have seen plenty of worse gfs runs recently, the cold winds from eastern europe could develop into something more potent if the idea gathers any momentum.

Edited November 6, 2011 by Polar_ Low

[phil nw.]

I'm afraid Phil that some are being just a touch easy shall we say with some meteorological terms and what a term actually means rather than analysing charts a touch more carefully. Always also with the proviso its one run..

Its looking like being a very very long winter in terms of reading the model thread judging by the hunting for cold on every run that is already occurring.

Thanks John--i thought i was missing something,lol.

[bobbydog]

i may be completely misunderstanding what i am looking at here, but would this not give a very positive NAO?

[johnholmes]

i may be completely misunderstanding what i am looking at here, but would this not give a very positive NAO?

correct

Does that mean the Gfs 12z will also be ditched? the gfs 12z looks nothing like the 00z. I have seen plenty of worse gfs runs recently, the cold winds from eastern europe could develop into something more potent if the idea gathers any momentum.

you have to remember that there may be quite technical reasons and not necessarily impinging on UK weather for NOAA to make negative comments about the GFS run.

It happens all the year round but of course few read their ouputs other than in the approaching winter season and through it.

[SMU]

If you take the ECM at face value its backing the whole pattern westwards in 2 cycles-

Look at the inland runner over the NE states at 144 & the ridging to the east of it-

Thats getting linked with ridging from scandi -

The whole pattern is the same at 144 except the inland runner over canada is up west of the great lakes & the ridging a lot further west as well-

The 264 chart would look very similar to the 168 except the next cold shot coming out the pole would be further west-

All in all, still mild in the near future, however the pattern is progessively looking better as we come into the 8/9/10 day timeframes-

regards

Steve

[nick sussex]

NOAA in their updated discussions have excluded the GFS operational runs regarding that all important eastern USA troughing.

MODELS DO MARCH A HIGH

AMPLITUDE TROF ACROSS THE ERN HALF OF THE COUNTRY BY EARLY FRI.

UPSTREAM...MODELS CLUSTER REASONABLY WELL ON FORMING A CLOSED

UPPER LOW VICINITY OF 40N/135W THRU THU DAY 4. BEYOND THAT

TIME...THE ECMWF/CANADIAN/UKMET FAMILY OF SOLUTIONS AND A FAIR

NUMBER OF ENSEMBLES SUPPORT THE IDEA THAT CONSENSUS OF THE WRN

CLUSTER OF DETERMINISTIC MODELS...EXCLUDING THE GFS...WILL BE MORE

ACCURATE.

This is good news in terms of how the pattern could evolve, although nothing shouts sledges and ear muffs the ECM at least brings a lowering in temps as the high centres further west and north.

We really need to see a further amplifying trough over the eastern USA which could finally force much lower heights into Scandi, but overall for the timebeing the ECM is not too bad and that PV at least looks like it doesn't want to start a courtship with Greenland!

[chionomaniac]

Mmm,I always regard a -NAO to be when we have Upper Heights north of the Polar front at High latitudes Chiono, with energy much more into the Southern Jet with low pressure towards the Azores.

On that chart it looks at best neutral with those hts around mid-latitude.

I don`t wish to nickpick for the sake of it mate but i think it`s important when we use these terms that we use the classic meanings otherwise newer members can get confused.

Having said all that i don`t think we are too far away where we could evolve into a -NAO- but not this week.

Anyway thanks for your reply.

I was commenting on the fact because the NAO forecasts had been trending negative ( http://www.newx-forecasts.com/nao.html ) and was trying to explain that just because the trend was negative it does not necessarily mean that the classic Greenland high is going to occur.

The point I was trying to emphasize and obviously still need to by the confusion by the following posts is that the NAO is measured as a pressure difference from average between Gibraltar and Iceland and not the whole of the north Atlantic.

http://www.newx-forecasts.com/nao.html

So it is possible to have a slight building/ lowering of heights over these areas without the full high latitude block.

[bobbydog]

correct

thanks john. i realise this is at the end of the run, therefore this particular chart is unlikely to occur, but it is nice to know i am reading the charts correctly

[Frosty.]

correct you have to remember that there may be quite technical reasons and not necessarily impinging on UK weather for NOAA to make negative comments about the GFS run. It happens all the year round but of course few read their ouputs other than in the approaching winter season and through it.

Hi John,

It looks like the discussion yesterday about the Ecm longer range modelling beyond T+240 hours has already begun to impact on the latest ecm run compared to the 00z this morning, I just noticed Steve Murr has commented on the latest ecm and it sounds like something colder after mid month is beginning to look more realistic...are they your own thoughts?

Edited November 6, 2011 by Polar_ Low

[phil nw.]

I was commenting on the fact because the NAO forecasts had been trending negative ( http://www.newx-forecasts.com/nao.html ) and was trying to explain that just because the trend was negative it does not necessarily mean that the classic Greenland high is going to occur.

The point I was trying to emphasize and obviously still need to by the confusion by the following posts is that the NAO is measured as a pressure difference from average between Gibraltar and Iceland and not the whole of the north Atlantic.

http://www.newx-forecasts.com/nao.html

So it is possible to have a slight building/ lowering of heights over these areas without the full high latitude block.

Thanks Chiono for clarifying.

I have posted the Wiki link explaining NAO states and how they are measured--for the benefit of any members that still need clarification.

http://en.wikipedia....tic_oscillation

Just to quote the first sentence

"The North Atlantic oscillation (NAO) is a climatic phenomenon in the North Atlantic Ocean of fluctuations in the difference of atmospheric pressure at sea level between the Icelandic low and the Azores high."

I think we have covered this now.

Edited November 6, 2011 by phil n.warks.

[ANYWEATHER]

If I look at the Gfs with the 06z and 12z one run puts some powerful heights across the Poles the Other not. Im certainly not looking for anything cold in the near future, but as regards the models they have" NO "clue past 240 hrs. Of course the pattern could change pretty quickly but for now, the same as.... , but perhaps some stormy weather in the West , with this set-up.!

[chionomaniac]

Thanks Chinio for clarifying.

I have posted the Wiki link explaining NAO states and how they are measured--for the benefit of any members that still need clarification.

http://en.wikipedia....tic_oscillation

Just to quote the first sentence

"The North Atlantic oscillation (NAO) is a climatic phenomenon in the North Atlantic Ocean of fluctuations in the difference of atmospheric pressure at sea level between the Icelandic low and the Azores high."

I think we have covered this now.

Yes I agree Phil........ but

out of interest - is the following chart a positive or negative NAO signature?

[ANYWEATHER]

Sorry Folks I should of Put this on my Previous Post.. :rofl: :rofl: :rofl:

Yes I agree Phil........ but

out of interest - is the following chart a positive or negative NAO signature?

I think that you wil find that is a Western based negative NAO....

[phil nw.]

Yes I agree Phil........ but

out of interest - is the following chart a positive or negative NAO signature?

Negative,lol yes that come out on the later ECM run--after our initial exchanges.

Edited November 6, 2011 by phil n.warks.