Model Output Discussion - Early November Onwards

[chionomaniac]

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

Yes and have you seen the ECM850's for that time?!!!!!

That was the point I clumsily laboured to get across!

[phil nw.]

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

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

Have to disagree Anyweather,

Icelandic low pressure on both.

The chart on the left i would say +NAO and on the right neutral at best.

See postings above.

[johnholmes]

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.

not always my favourite place for meteorological definitions but wilki suggests this

The NAO has multiple possible definitions. The easiest to understand are those based on measuring the seasonal average air pressure difference between stations, such as:

• Lisbon, Portugal and Stykkisholmur/Reykjavik, Iceland
  
• Ponta Delgada, Azores and Stykkisholmur/Reykjavik, Iceland
  
• Azores (1865–2002), Gibraltar (1821–2007), and Reykjavik, Iceland^[1]
  

I really think that we are wasting posts by discussing whether a particular synoptic chart currently shown by the models is showing a -ve or a +ve sign.

Forecasters rarely refer to this in the 'normal' synoptic time scale when preparing forecasts for issue, say on a time scale of 1-10 days ahead.

Its something that CAN be used CAREFULLY as a tool to trying to predict how the atmosphere might behave in timescales beyond that. I find the AO/NAO predictions are quite accurate out to about 10 days, fairly accurate to about 15 and less so but still useful when used with other tele-links beyond that.

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

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

does it really matter chio?

[chionomaniac]

does it really matter chio?

Not really John, but it is useful to demonstrate a -ve NAO that brings exceptionally warm weather.

I think that some may look at the NAO forecasts without taking into consideration the NWP output.

[johnholmes]

I think that some may look at the NAO forecasts without taking into consideration the NWP output.

I suspect you are right

Edited November 6, 2011 by Paul

[phil nw.]

Yes and have you seen the ECM850's for that time?!!!!!

That was the point I clumsily laboured to get across!

Yes i see what you were getting at--.Mild uppers from the South.

Technically -NAO but it`s a warm block extending from the Euro parent formed South of the PJF and soon collapses and we are back to square one by T216.

I don`t think we are too far away for something better C to be honest as the core of the Vortex is modelled on the Russian side of the Arctic at T168 dropping cold air into Russia and E.Europe.

We can see attempts on this ECM run and UKMO out to T144 for Hts towards Greenland .

We need some more energy going South to undercut.

[Snowmad79]

Yes and have you seen the ECM850's for that time?!!!!!

That was the point I clumsily laboured to get across!

Its warm because that is a developing NAO signature, not a sustained -NAO

[chionomaniac]

Yes i see what you were getting at--.Mild uppers from the South.

Technically -NAO but it`s a warm block extending from the Euro parent formed South of the PJF and soon collapses and we are back to square one by T216.

I don`t think we are too far away for something better C to be honest as the core of the Vortex is modelled on the Russian side of the Arctic at T168 dropping cold air into Russia and E.Europe.

We can see attempts on this ECM run and UKMO out to T144 for Hts towards Greenland .

We need some more energy going South to undercut.

Yes, I actually agree but where I differ from Steve Murr is that I think the we need a couple of attempts to bring down the Atlantic trough/ Scandi block. The first is thwarted and repelled but sets us up for a second attempt where Scandi heights will be more readily lowered, thus allowing heights to the NW to build and sustain. Then we may see the more traditional -ve NAO!

[snowfall09]

Hi all,

There's a program that may be of some interest for everyone on this thread, on bbc 2 at 9:00 tonight its called 'will it snow' and experts are to asses the uk weather in hope of finding out if it will be as snowy as last winter

[beng]

Since we're talking a bit about the NAO, Steve M posted this chart over at Two

http://www.wetterzen...00119621226.gif

which I think is a lovely example of how we don't always have to have a strongly negative AO, to get a decent negative NAO. Provided it's not rip roaringly negative up there, and the Vortex is out of the way (i.e. not too close to Greenland - preferably there's some kind of split too), then the UK can do okay. This was the start of the great 62/63 winter - a few days before this chart an easterly blast (~ -6 850s) had crossed parts of the UK - but with a very cold surface flow). Despite the real cold being behind the frontal system coming down from the North, there was enough cold due to the embedded surface layer to produce a big snow event.

Edited November 6, 2011 by beng

[phil nw.]

Since we're talking a bit about the NAO, Steve M posted this chart over at Two

http://www.wetterzen...00119621226.gif

which I think is a lovely example of how we don't always have to have a strongly negative AO, to get a decent negative NAO. Provided it's not rip roaringly negative up there, and the Vortex is out of the way (i.e. not too close to Greenland - preferably there's some kind of split too), then the UK can do okay. This was the start of the great 62/63 winter - a few days before this chart an easterly blast (~ -6 850s) had crossed parts of the UK - but with a very cold surface flow). Despite the real cold being behind the frontal system coming down from the North, there was enough cold due to the embedded surface layer to produce a big snow event.

Yes the Winter that started it all for me.

Suprisingly looking through the archives there were many days when the sypnotics were not "perfect` with quite modest Upper air temps.

However once the snow lay and with a lot of clear nights between the snow we got very cold surface conditions at times.

Edited November 6, 2011 by phil n.warks.

[Snowmadsam]

Hi all,

There's a program that may be of some interest for everyone on this thread, on bbc 2 at 9:00 tonight its called 'will it snow' and experts are to asses the uk weather in hope of finding out if it will be as snowy as last winter

thank you watching it now

[Grimsby Snow Lover]

Hi all,

There's a program that may be of some interest for everyone on this thread, on bbc 2 at 9:00 tonight its called 'will it snow' and experts are to asses the uk weather in hope of finding out if it will be as snowy as last winter

Thanks mate, just sky+ it.

[bluearmy]

the ecm ens mean and spreads show the mean ridge centred over the uk by day 10 with the colder uppers making it as far west as denmark. its slowly retrogressive and i tend to agree with chio - we're getting there but rather more slowly than some would like to see. from my perspective, 10 days is only mid november and i'd rather not see a stellar pattern at a time of year which is unlikely to deliver the best surface consequences. give it another few weeks ...........

[95 Degrees]

Don't know why people call British weather unpredictable, very predictable boring British like weather for everywhere next week until Thursday where fronts don't look like going that far east being shown on all models with widespread cloud and little temperature variation day and night with drizzle at times. hopefully the very mild and sunnier weather shown on the models for late next week ends of being true, where are the Atlantic SW winds?

[Snowmadsam]

I assume the next GFS model (18Z) will start rolling out within the next 15 minutes?

Just saw netweather on Will it Snow on BBC Two

Edited November 6, 2011 by Snowmadsam

[Grimsby Snow Lover]

I assume the next GFS model (18Z) will start rolling out within the next 15 minutes?

Just saw netweather on Will it Snow on BBC Two

As soon as the wife goes to sleep I will be putting it on the telly lol.

She is now snoring, a definate sign to put the snow programme on now.

Edited November 6, 2011 by Grimsby Snow Lover

[peterf]

miss Humble reckons we are now in winter?

[Frosty.]

It's a snowy outlook on bbc2 in the northeast and scotland for late november, wintry showers throughout december and then blizzards in the new year...so that's winter sorted

The models don't show it yet but I now believe it's going to get colder before december and the ecm is already hinting at change.

[Tim Bland]

Wouldn't bother if I was you! They basically said "who knows" and dragged it on for an hour! Not 1 mention of forecasting models!

[Snowstorm1]

miss Humble reckons we are now in winter?

Oh well it must be true then...

[Fozfoster]

As soon as the wife goes to sleep I will be putting it on the telly lol.

She is now snoring, a definate sign to put the snow programme on now.

I think you might be a sleep by the end. GSL. zzzzzzzzzzzz.

[peterf]

i thought it was a poor dumbed down show, with very little to offer to the viewer.

why she said we are now in winter beggars belief.i'm still picking strawberries and the trees havn't shed 20% of leaf yet lol.

[Grimsby Snow Lover]

Wouldn't bother if I was you! They basically said "who knows" and dragged it on for an hour! Not 1 mention of forecasting models!

That will be because they will think we are too stupid to understand forecasting models. In the bbc's eyes only those working for the met are intelligent enough to understand them. Thats my opinion anyway.

[Isolated Frost]

I'm no moderator but surely all of this is in the wrong topic? I know this post is off-topic, but it's only to help prevent all of this. http://forum.netweather.tv/topic/69782-weather-in-the-general-media-newspaper-features-etc/page__pid__2155582__st__220#entry2155582

Thanks