Model Output Discussion 1200 hrs 30/09/14

[snowking]

It should be noted re: ECM Greenland heights - this seems to have been a bias over the past couple of years around this time of the year in the extended timeframe. Even back in 2012/13 there was constant suggestion of more significant retrogression and building of heights in to this region from the ECM, none of which really bore fruit.

So my advice would be when the ECM op is out on its own with this suggestion it might be best to apply some caution to the situation.

SK

[Gibby]

It looks like the different ECM op at Day 10 was out of kilter with its ensemble pack as the 10 Day Mean keeps the North/South mild split going.

 

http://www.wetterzentrale.de/pics/Reem2401.gif

 

[SMU]

ECM hasn't updated on Meteociel so you are using the wrong charts, however here is the 00z ECM at 168 & 192

 

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

 

http://www.wetterzentrale.de/pics/Recm1921.gif

No Sign of any vortex getting into shape with both weak NAO & AO signatures- probs in the order of -0.5 ish.

 

GEM is similar today with slightly more positive blocking towards Greenland-

http://modeles.meteociel.fr/modeles/gem/runs/2014102100/gemnh-0-168.png?00

 

Whilst its not Strong blocking, the heights are circa 528-544 @ 500 MB, where as the usual October Mean would suggest it should be nearer 500-504 DAM ...

 

In Summary around 60N a good anomaly signature for October & weak negative AO blocking, however at this time of year a weak negative AO is a STRONG inverse to the norm............

S

[knocker]

The ECM ens continuing with a similar pattern and one which is continued in the monthly update as noted.

 

[gottolovethisweather]

The EPS ens monthlies update. The temps are around average for month except the Arctic which remains above. Generally unsettled westerlies. Note they haven't quite loaded in the correct order

 

Sorry can you help me out here.

 

Do the yellows and red colours suggest higher than average Air Pressure readings and the blues, lower pressure anomaly readings? Or are they higher up in the atmosphere, i.e. not relative to what we get at the surface.

Edited October 21, 2014 by gottolovethisweather

[knocker]

Sorry can you help me out here.

 

Do the yellows and red colours suggest higher than average Air Pressure readings and the blues, lower pressure anomaly readings? Or are they higher up in the atmosphere, i.e. not relative to what we get at the surface.

 

The yellow and red are the positive anomalies given in decametres (dam) and the blues are the negative anomaly. In other words the departure of the geopotential height from average at 500mb. The NOAA charts do it differently with red and blue dashed lines as you know but it amounts to the same thing. You have to be a bit careful with the charts as the way they are presented can tend to overemphasise.

 

They are no different to the other anomaly charts people show on here apart from NOAA.

 

In fact JH's explanation of the NOAA chart covers it really.

 

500mb charts-are they a useful guide-8 feb 12.pdf

Edited October 21, 2014 by knocker

[Gibby]

ECM hasn't updated on Meteociel so you are using the wrong charts, however here is the 00z ECM at 168 & 192

 

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

 

http://www.wetterzentrale.de/pics/Recm1921.gif

No Sign of any vortex getting into shape with both weak NAO & AO signatures- probs in the order of -0.5 ish.

 

GEM is similar today with slightly more positive blocking towards Greenland-

http://modeles.meteociel.fr/modeles/gem/runs/2014102100/gemnh-0-168.png?00

 

Whilst its not Strong blocking, the heights are circa 528-544 @ 500 MB, where as the usual October Mean would suggest it should be nearer 500-504 DAM ...

 

In Summary around 60N a good anomaly signature for October & weak negative AO blocking, however at this time of year a weak negative AO is a STRONG inverse to the norm............

S

 

The ECM Ens data had updated at the time of  my above post so I can confirm a North/South split in a mild Westerly setup for the foreseeable from ECM today and I expect the Met Office update today to confirm that later.

 

PS I used wetter data for my main report today from ECM

Edited October 21, 2014 by Gibby

[johnholmes]

Sorry can you help me out here.

 

Do the yellows and red colours suggest higher than average Air Pressure readings and the blues, lower pressure anomaly readings? Or are they higher up in the atmosphere, i.e. not relative to what we get at the surface.

 

Be very careful about anomalies. It takes a lot of watching these charts to feel reasonably confident in using the anomaly part. Knocker explains the colours fine but be careful. The best thing is to look at the contours, if you like isobars at 500mb around 18000ft. They govern what happens at the surface rather more than the other way round. Watching the 'anomaly' charts will give a good feel for what the upper air pattern is likely to be 6-15 days down the line. As with all charts from whatever source, continuity and consistency are key to making a considered judgement on the upper air pattern. Over the years I have found them, with a lot of care and time analysing them each day, as more consistent and accurate than the 2x or 4x synoptic outputs from GFS/ECMWF etc. Somewhere in the Guides is a post from me about using them, not sure just where, you might find it useful. The really hard part is then trying to work out what the surface pattern will be beneath the 500mb pattern. Much more difficult but the upper pattern will give a good guide to the overall type of weather, settled or unsettled, or changeable, warmer or colder than average, wetter or drier than average.

Hope that helps and if you want please pm me and I am happy to chat about them to you.

Edited October 21, 2014 by johnholmes

[knocker]

Be very careful about anomalies. It takes a lot of watching these charts to feel reasonably confident in using the anomaly part. Knocker explains the colours fine but be careful. The best thing is to look at the contours, if you like isobars at 500mb around 18000ft. They govern what happens at the surface rather more than the other way round. Watching the 'anomaly' charts will give a good feel for what the upper air pattern is likely to be 6-15 days down the line. As with all charts from whatever source, continuity and consistency are key to making a considered judgement on the upper air pattern. over the years I have found them, with a lot of care and time analysing them each day, as more consistent and accurate than the 2x or 4x synoptic outputs from GFS/ECMWF etc. Somewhere in the Guides is a post from me about using them, not sure just where, you might find it useful. The really hard part is then trying to work out what the surface pattern will be beneath the 500mb pattern. Much more difficult but the upper pattern will give a good guide to the overall type of weather, settled or unsettled, or chageable, warmer or colder than average, wetter or drier than average.

Hope that helps and if you want please pm me and I am happy to chat about them to you.

 

John I've just added part one of your guide to my original post.

[johnholmes]

John I've just added part one of your guide to my original post.

 

ta for that mate, not sure if I ever got round to doing part 2?

 

Part 2 has been done along with other illustrations of using these charts. When/if I get time I will put them all into 1 post as a pdf with a heading to make them easy to find. Then it is not cluttering up the current model thread.

Edited October 21, 2014 by johnholmes

[gottolovethisweather]

The yellow and red are the positive anomalies given in decametres (dam) and the blues are the negative anomaly. In other words the departure of the geopotential height from average at 500mb. The NOAA charts do it differently with red and blue dashed lines as you know but it amounts to the same thing. You have to be a bit careful with the charts as the way they are presented can tend to overemphasise.

 

They are no different to the other anomaly charts people show on here apart from NOAA.

 

In fact JH's explanation of the NOAA chart covers it really.

 

Thanks Knocker. Will re-read the learning again, I think I did so a few years back but I soon forget the ins and outs of our atmosphere understandings. I also quickly checked online (although it'll be shown in the attached link I suspect) for those unaware of what the 500mb readings are, these are measurements taken at approximately 3 miles up, some 18,000 feet up in the atmosphere. 

Edited October 21, 2014 by gottolovethisweather

[Radiating Dendrite]

Thanks Knocker. Will re-read the learning again, I think I did so a few years back but I soon forget the ins and outs of our atmosphere understandings. I also quickly checked online (although it'll be shown in the attached link I suspect) for those unaware of what the 500mb readings are, these are measurements taken at approximately 3km up, some 18,000 feet up in the atmosphere. 

 

Sorry to be pedantic but 3km is 9842 feet.

[gottolovethisweather]

Be very careful about anomalies. It takes a lot of watching these charts to feel reasonably confident in using the anomaly part. Knocker explains the colours fine but be careful. The best thing is to look at the contours, if you like isobars at 500mb around 18000ft. They govern what happens at the surface rather more than the other way round. Watching the 'anomaly' charts will give a good feel for what the upper air pattern is likely to be 6-15 days down the line. As with all charts from whatever source, continuity and consistency are key to making a considered judgement on the upper air pattern. Over the years I have found them, with a lot of care and time analysing them each day, as more consistent and accurate than the 2x or 4x synoptic outputs from GFS/ECMWF etc. Somewhere in the Guides is a post from me about using them, not sure just where, you might find it useful. The really hard part is then trying to work out what the surface pattern will be beneath the 500mb pattern. Much more difficult but the upper pattern will give a good guide to the overall type of weather, settled or unsettled, or changeable, warmer or colder than average, wetter or drier than average.

Hope that helps and if you want please pm me and I am happy to chat about them to you.

 

Thanks JH and the two lines I've highlighted above stand out for me in your post. This illustrates how we all need to constantly watch for trends amongst many differing weather parameters and simply not to take one set of charts as a given for a specific forthcoming forecast period.   Clearly for me, it is your second highlighted comment on which I do struggle with in particular.

Edited October 21, 2014 by gottolovethisweather

[johnholmes]

500mb charts, how to use them and a few examples. It is a very large pdf something like 14 pages long with charts to illustrate, hence as a pdf for folk to decide if they wish to download or not, copied into the technical area as it may be easier to find in the winter season.

 

bugger! forgotten how to create a pdf file so can someone help the poor old fool please?

 

 

[Gael_Force]

Sorry to be pedantic but 3km is 9842 feet.

 

This graphic from, I think, Matt Hugo, has a nice clear scale of where everything is at. 500mb is roughly 18,000 feet up.

[johnholmes]

think its sorted thanks folks-old age is a sad affliction-buggers up the memory something rotten

herewith

 

500mb various posts in order of posting-21 oct 2014.doc

 

it has 16 pages so may take a while to download for some-free choice to look or ignore, will also post it into the technical thread although the contents are not at all technical

Edited October 21, 2014 by johnholmes

[phil nw.]

can't work out how I used to do it=the problem!

Hi John,

I have sent you a PM.

 

edit,

just seen your last posting John-glad it's sorted.

Edited October 21, 2014 by phil nw.

[Vorticity0123]

think its sorted thanks folks-old age is a sad affliction-buggers up the memory something rotten

herewith

 

500mb various posts in order of posting-21 oct 2014.doc

 

it has 16 pages so may take a while to download for some-free choice to look or ignore, will also post it into the technical thread although the contents are not at all technical

 

For the ones who prefer to use the PDF-version, here it is:

 

500mb various posts in order of posting-21 oct 2014.pdf

 

Hope this helps 

Edited October 21, 2014 by Vorticity0123

[Barry12]

GFS 12z is looking good, polar vortex very weak and some good blocking

 

 

 

Some strong heights moving into the arctic on ECM

 

Edited October 21, 2014 by Barry95

[phil nw.]

All 3 main models continue to show the changeable west/south westerly flow over the UK continuing.

Whilst there are indeed -ve ht anomalies over the Arctic the persistence of Icelandic/Greenland low pressure is the main driver of our current outlook.

Little change seems likely with occasional bands of rain or showers interspersed with some transient ridges giving drier intervals,particularly further south.

[ANYWEATHER]

A continuation of the unsettled weather looks likely right to months end .with  fluctuations  in the temperatures between cold and mild, pretty normal Autumn weather tbh!  Gone ,has the predicted pressure rise from the south as was hinted at from the ecm and gfs a few days ago as early as next week! giving us some very high unseasonable temperatures,,,,,It looks like some windows of fine and calm weather on offer, resulting in some frost, mist and fog. At last we have returned to a more normal Autumn pattern.    

[Ali1977]

T384 would be nice on the 00Z, I think that would turn out to be a prolonged cold spell.
Can't post images on my phone sorry.

 

Edited October 22, 2014 by Polar Maritime
Popped chart in for you.

[bluearmy]

T384 would be nice on the 00Z, I think that would turn out to be a prolonged cold spell.

Can't post images on my phone sorry.

There are forecasters who see a Canadian block stretching over Greenland to be the main upstream player D/J. not sure about feb. wouldn't be a surprise to see the system making some 'dry runs' at what could become a repeating general pattern. Latter part gfs op never worth dissecting in any detail but if this pattern begins to show more than one might expect it to .................

EDIT: note that ECM op at day 6 is raising heights over Canada

Edited October 22, 2014 by bluearmy

[knocker]

This morning GEFS anomalies are basically thus. D10 Cooler air Greenland mid Atlantic with warmer air Siberia to Southwest approaches but of no great intensity nor amplification upstream so basically a zonal flow with low pressure, albeit quite slack in Atlantic with above average temps in UK

 

Further down the line the slightly more positive anomalies in the Atlantic thus replacing the dominate low pressure with HP. No sign of a significant PV. Temps still above average. Not a very dynamic pattern it has to be said but little indication of any influx of colder air.

Edited October 22, 2014 by knocker

[cyclonic happiness]

Some nice charts this morning with the GFS especially dishing out the goodies with an almost northerly toppler (NN/W) followed the next week by a high pressure forming over the BI which then starts to retrograde to wards the northern Atlantic and southern Greenland.

 

I'll go to work happy after seeing that :-)

 

(at least it will be cooler than now....more seasonable)