Model Output Discussion 26/08/2012

[Geordiesnow]

I think what the ECM is showing is at this moment in time bit of a longshot as the major player for such a flow to happen is "Nadine" it appears although no doubt the Euro high certainly plays some part aswell. Will certainly be interesting to keep an eye on it though.

At the moment, it seems a case of winds coming from the Atlantic with more of a favour of polar westerly which may turn into a mild SW'ly if the jet stream favours this.

[TonyH]

Seems Nadine may not be done with us yet. The actual Nadine still well out over the Atlantic merging with the bigger low on the jet stream Thursday and which MAY bring us warm tropical air next weekend (according to ECM anyway):

[snowstorm445]

The weather in Autumn does not determine what happens during winter. In fact, according to GP, a cold outlook for October tends to favour a milder winter, so there isn't much harm having high pressure nearby.

I really doubt we will see the temperatures we saw last October (which was an absolutely vile month btw). Highs of only in the low 20s at least. Bear in mind that the NAO is currently in a fairly neutral phase* to neutral phase, which means the normal westerly pattern will probably prevail.

Sorry, neutral to slightly positive.

[johnholmes]

Based on the outputs from the anomaly charts, and their trend over the past 2-3 days, still only a trend, I would not be too surprised to see a fairly warmish 500mb flow from s outh of west before the end of the first week in October. A bit early to 'go' for it but the trends are going that way at the moment.

I made these notes this morning

ec-gfs

fri 28 sept

ec-gfs

both show changes in the previous broad wly flow with height rises on both to the both, ec a touch further east than gfs shows, both treat the trough changes a bit differently with gfs sinking the low/trough further south than ec.

Wait for noaa this evening to see if it shows something similar and ec-gfs tomorrow but it may be a change is on the way?

and this note after seeing NOAA this evening

noaa

once again the 8-14 is much less meridional in parts and also less +/- than the 6-10 but a similar ‘tale’ really and a follow on from the last issues

it does tend to mirror to some extent the idea from ec-gfs this morning

all 3 have a trough in about the same place to give a flow s of west into the ukalthough noaa is more wsw

all 3 also raise heights over uk-not much but 4-6dm

so worth seeing what the picture is by Monday although the Sat and Sun outputs should give a clear enough indication before then?

Edited September 28, 2012 by johnholmes

[gottolovethisweather]

http://forum.netweat...80#entry2369718

Many Thanks John, I have clicked on the follow thread link so should get updates from here on in.

[Eskimo]

The thing that concerns me if the ecm is right would be a similar pattern to last october when we also had a late heatwave with temps touching 30c and then the weather patterns were absolutely dire for cold prospects for many weeks, well into winter actually before we got any cold weather of note, the mid to late autumn was generally very mild, I hope the weather does not have a memory and fancies a repeat. I'm looking for a more amplified pattern to arrive as we go deeper into autumn, as GP said recently..please no repeat of what happened in autumn and early winter last year.

Remember comparing two consecutive years and their weather patterns doesn't necessarily mean it will be the same.

[lorenzo]

Always wondered which mountains in the Tropics contributed to Mountain Torques? GP can you confirm>

[Polar Maritime]

Always wondered which mountains in the Tropics contributed to Mountain Torques? GP can you confirm>

The Altiplano, Or high plain of Bolivia and Peru...?

[Frosty.]

According to the latest ensemble mean, we can look forward to another anticyclonic spell from the end of next week onwards through to mid october and beyond, the gfs ens mean has changed significantly in the longer range and now mirrors what the ecm was showing yesterday, the ecm 12z mean from last night sticks to it's guns with a settled further outlook. The next week remains generally unsettled but with a few drier and brighter days but then the pattern looks like becoming much more benign with light winds, plenty of sunshine but at this time of year, there is probably going to be a lot of mist and fog overnight but clearing to warm hazy afternoon sunshine, it could become very warm as the flow is from the south.

[Gibby]

Good morning. Here's how the 00zs shape up from the big three this morning.

All models are united in showing a ridge of High pressure crossing East today. Beyond that and lasting through much of next week sees Low pressure bear down on the UK from off the Atlantic with a Low centre trundling East to the North of Scotland through the week. Disturbances in the flow will enhance the complexity of the system as it becomes very slow to move away late next week. All areas will see some rain by late tomorrow with a very showery week to follow with some heavy bands of rain thrown in for good measure, especially towards midweek. It will feel cool and be breezy for much of the time, even more so by the end of the week as winds turn more towards the NW.

GFS then brings a chilly ridge in from the West next weekend with a quieter few days with some sunshine and the chance of mist and fog patches overnight together with a touch of frost in places. In the following week (FI) GFS shows High pressure moving quickly away into Europe at the expense of a deep low pressure moving in from the West and settling over the UK for the remainder of the run. The pattern is not dissimilar to the system earlier this week as it is very slow to move off giving days of showers and prolonged rainfall for many in chilly air, the Low finally filling up in situ at the end of the run.

The GFS Ensembles continue to show a steady decline into mid Autumn for 850's in line with the long term mean, though at times they fall below average in what looks to be a changeable and Atlantic based weather pattern with some rain at times for all.

The Jet flow currently flowing SE over the UK takes up a West to East motion over Britain in a few days time, gradually sinking South as it develops a trough over the UK later next week.

UKMO for midnight on Friday shows a Low pressure west of Norway with a showery trough lying SW over Britain maintaining an unsettled and cool day next Friday.

ECM follows the GFS route this morning bringing in a couple of cool and dry days next weekend before Low pressure nudges in from the West once more with rain and showers returning to end the run.

In Summary the weather looks like staying rather unsettled over the next few weeks. the first week looks very showery and blustery and after a cool and dry weekend being possible week 2 looks much more likely to be unsettled too this morning as both GFS and ECM pull high pressure quickly away from Britain into Europe at the expenseof Atlantic Low pressure returning.

Edited September 29, 2012 by Gibby

[SMU]

No sign of any warmth there as depicted by the theta Charts- If anything cold at the surface & if the 06z is accurate ( not always a good run ) then frost appearing in the forecasts- & snow over the hills in Scotland as mentioned.

S

[UV-RAY]

http://modeles.meteo...snh-6-168.png?6

No sign of any warmth there as depicted by the theta Charts- If anything cold at the surface & if the 06z is accurate ( not always a good run ) then frost appearing in the forecasts- & snow over the hills in Scotland as mentioned.

S

Is that the same 06z you say to ignore in winter Steve?

[Fozfoster]

Is that the same 06z you say to ignore in winter Steve?

In Steve's defense i think the in brackets bit (not always a good run) is implying its a poor model.

[UV-RAY]

In Steve's defense i think the in brackets bit (not always a good run) is implying its a poor model.

It was a tongue in cheek reply Foz, I enjoy Steve's posts.

[SMU]

The 06z is the worst run of the day-

However irrespective of the fact its quite a cold run at the surface- out to 168 it does depict the model 'trending' for the last 24 hours, of course if you didnt believe the model output from yesterday anyway ( IE thoughts of some sort of indian Summer) then it doesnt come as a surprise!

Snow in the news next week for sure- obviously it will be overhyped but still- nice to see...

S

[Tattooed Fox]

Hi Steve,

Have u seen the front page of the Daily Express? Seems they think Armageddon is going to happen regards to the weather.

[snowstorm445]

The 06z is the worst run of the day-

However irrespective of the fact its quite a cold run at the surface- out to 168 it does depict the model 'trending' for the last 24 hours, of course if you didnt believe the model output from yesterday anyway ( IE thoughts of some sort of indian Summer) then it doesnt come as a surprise!

Snow in the news next week for sure- obviously it will be overhyped but still- nice to see...

S

I thought that 18z run was the worst one of the day. They don't call it the "pub run" for nothing.

12z is always the most accurate I believe, regardless of your weather preferences. I remember last year people would declare if a model was showing cold, that it was "accurate", and if the same model later showed "mild", it was "rubbish". Bit revisionist if you ask me.

[SMU]

In order of Fail.

06z 18z 00z 12z-

I will check the statistics at some point soon-

Steve

[johnholmes]

I'd love to see the statistics to see which if any GFS run is 'worse' than the others.

In my book I am talking about accuracy, did the subsequent weather at sensible time scales, T+12 out to T+240 perhaps show the model run was correct. I have never seen anything from NOAA to suggest one run is more accurate than another but that may just be me not delving far enough?

[SMU]

Hi John-

I cant add the link as im at work- but the NOAA have a model deterministic page which has RMS errors at day 4 5 & 6 -

They have graphs for all the models together plotted- ECM, UKMET, SHIPS , GFS ( 00z IIRC)

they alos bundle the 4 GFS runs together for areas of the globe-

NHem, SHem, Arctic, Pacific, europe etc

06z GFS is by far the worst performing run which is why I always ditch it.

best regards

Steve

( HELLO MATT)

Edited September 29, 2012 by Steve Murr

[lorenzo]

Verification links.

ECM for the win..

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/

http://www.emc.ncep..../html/acz6.html

A site to play around with that loops model bias.

http://www.hpc.ncep....bias/index.html

In respect of the GFS, comparing day to day 12z to 12z would be the way to go..

Edited September 29, 2012 by lorenzo

[chionomaniac]

GFS interrun statistics:

http://www.emc.ncep....gmb/STATS_vsdb/

Goto RHS and program in what you want.

Edited September 29, 2012 by chionomaniac

[IDO]

The pattern up to T144 is unsettled coolish autumnal.

Afterwards anyone's guess.

The models disagree; members in these models are split, and there is not even any pattern; instead runs flip-flopping between unsettled or the alternative, HP.

The HP option is interesting, with plenty of potential; below average temps. though predominantly settled, but with potential for LP blocking at the outer reaches of FI (on GFS 06z).

The SW'ly option will delay anything interesting for another 7-10 days, at least.

[johnholmes]

Verification links.

ECM for the win..

http://www.emc.ncep....gmb/STATS_vsdb/

http://www.emc.ncep..../html/acz6.html

A site to play around with that loops model bias.

http://www.hpc.ncep....bias/index.html

In respect of the GFS, comparing day to day 12z to 12z would be the way to go..

thanks for that last link especially L, had not realised that was available. Sort of knocks on the head, albeit by a small margin, that the 06z is the worst?

And the link that I generally use for inter model checking shows all taking a tumble over the last few days; UK Met worse than GFS.

Edited September 29, 2012 by johnholmes

[johnholmes]

Hi John-

I cant add the link as im at work- but the NOAA have a model deterministic page which has RMS errors at day 4 5 & 6 -

They have graphs for all the models together plotted- ECM, UKMET, SHIPS , GFS ( 00z IIRC)

they alos bundle the 4 GFS runs together for areas of the globe-

NHem, SHem, Arctic, Pacific, europe etc

06z GFS is by far the worst performing run which is why I always ditch it.

best regards

Steve

( HELLO MATT)

cheers Steve, lorenzo has supllied them as I'm sure you have seen by now