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Model Output Discussion 01/09/17

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13 minutes ago, Man With Beard said:

Another winter season begins, another case of models getting overexcited in the Greenland region. Compare GFS T192 with T144:

gfs-0-192.png  gfs-0-144.png

For long-timers here, this was completely expected, I daresay?? Ridging into Greenland vs troughing over Canada modelled at D8-D10 = almost always troughing into Greenland when modelled at D5-D7.

GFS the culprit this time. 

Is there a model that does not have this tendency?

Ukmo but mainly because it goes no further than 168 hours. 

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Much more seasonal weather coming up.Maybe some frosts and Northerly outbreaks on the cards as we enter November.

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47 minutes ago, Man With Beard said:

Another winter season begins, another case of models getting overexcited in the Greenland region. Compare GFS T192 with T144:

gfs-0-192.png  gfs-0-144.png

For long-timers here, this was completely expected, I daresay?? Ridging into Greenland vs troughing over Canada modelled at D8-D10 = almost always troughing into Greenland when modelled at D5-D7.

GFS the culprit this time. 

Is there a model that does not have this tendency?

Yes it always seems to be the case year after year. It does make me wonder why this happens and if it would be possible for the models to be tweaked to correct this?

Height rises around or towards Greenland should always be viewed with a very sceptical eye until they get within at least 120hrs - probably less. That way you save yourself a lot of disappointment.

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17 minutes ago, Northern Sky said:

Yes it always seems to be the case year after year. It does make me wonder why this happens and if it would be possible for the models to be tweaked to correct this?

Height rises around or towards Greenland should always be viewed with a very sceptical eye until they get within at least 120hrs - probably less. That way you save yourself a lot of disappointment.

6z not quite so bad. Weakish UK heights sort of holding on. Yes is odd, though what is weird is that we have seen the height rises in Spring and Summer. 

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Weakish UK heights sinking to where it always likes to set up...and on the 06z to our south and then to the east. Only straw to grab at is Europe goes quite cold for a period and in the longer term it 'might' does us a favour if we can ever get hold of an easterly over winter. That continent needs to cool down.

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Another sub-seasonal model update....

I was making posts about MJO on Wednesday, talking about the forecast for it. But I have had another look at MJO and all of the equatorial waves.

IMG_2629.png

This MJO forecast shows the current MJO wave is actually associated with a Kelvin wave. Apart from being connected to the QBO, Kelvin waves aren't as important as the MJO though. Very interesting though. More to come.....

Edited by Snowy Hibbo
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21 minutes ago, oasis said:

6z not quite so bad. Weakish UK heights sort of holding on. Yes is odd, though what is weird is that we have seen the height rises in Spring and Summer. 

I think probably because spring and summer see the polar vortex disappear,hence the more northern blocking.

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To be honest, the 06Z OP continues to pique my interest.

The core of the HP remains well to the NW of the Azores even in far FI while the jet ridges round the mid-Atlantic HP and then SE over the British Isles.

What we aren't looking it is a long spell of tropical maritime air sourced from the Canaries or points further south or south west. The airflow is more west or even WNW at times so from south Greenland so a more seasonal temperature profile than in previous years for the first third of November.

It's also worth noting no strong signal for cyclogenesis with the Atlantic not overly strong so no autumnal storms at this stage - indeed, quite benign in the next week and we might see a bit more fog than we've had in previous years. All in all, at this stage, a more "typical" early November. It means nothing for the rest of winter.

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4 hours ago, blizzard81 said:

That almost semi permanent high the other side of the pole over western Alaska/eastern Russia does us no favours at all. When it balloons all it serves to do is fire up the pv over north eastern Canada which in turn fires up the Atlantic. This has happened over the last few winters now and looks to be there again this year. 

Is that the Pacific ridge you are alluding too? If so, then I certainly agree and don't quite get why people will be excited by this as I think the effects of cold weather on a UK perspective is quite minimal, yes the PV becomes disorganised but its useless for us if it does what you say it does and most of it heads into Canada and down the eastern seaboard and the other half heads into China leaving the UK and Scandinavia quite mild and deep cold air looking very far away from our shores. Of course, if the WAA heads up to the poles from the Atlantic side of the Arctic then things get more interesting as the PV will split into Scandinavia/Russia and Alaska and it suggests blocking over Scandinvia.

All that said though, the Arctic is too warm as it is and I don't see any benefits of a disrupted PV this early in the season and I rather see a rampant PV and stormy weather seeing as its still Autumn afterall, Sadly that is not the case at the moment as it look like we will be under the influence of fairly slack westerlies and fairly mild air so rather uninteresting outlook, not quite seeing much signs of a cold/dry start to November either really, if we get more amplification then maybe but most runs I seen dom't seem to back this up.

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1 hour ago, Northern Sky said:

Yes it always seems to be the case year after year. It does make me wonder why this happens and if it would be possible for the models to be tweaked to correct this?

Height rises around or towards Greenland should always be viewed with a very sceptical eye until they get within at least 120hrs - probably less. That way you save yourself a lot of disappointment.

I think the models struggle with the recent set up of less ice around Greenland. This feeds shortwave activity in the area and the height rises that are shown 10 days away get downgraded as we approach T0. Maybe they will improve over the years as more data is fed into the models. Basically, I think the models often show what could happen if there was more ice in the arctic and in particular around Greenland but sadly that's not what we have.

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I thought the whole idea of computer modelling was to factor in all those different parameters?

I for one think they are all useless and strangly seem to be getting more so.

Would it not be easier for all concerned to say "high pressure to the south of the uk will ocasionally ridge northwards after which some weakish fronts will effect the north and west,slight frost in places"

Take out the frost bit in summer and theres your forecast.

Simplistic I know but for 99.9% population who are'nt particularly interested it would suffice and 99% of the time would be accurate.

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4 minutes ago, SW1988 said:

I thought the whole idea of computer modelling was to factor in all those different parameters

Impossible to factor them all in. They try their best, but we are still refining it. TBH it is pretty amazing what we have achieved.... accurate 5-7 day outlooks of the weather. We are still working to refine longer range forecasts.

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The gfs this evening makes rather more of the wave on the trailing front next Thursday and has it 997mb just NW of Ireland. It then runs it east into Scotland, accompanied by rain and quite strong winds, on Friday and it continues on into southern Sweden leaving the UK in a showery NW with a small disturbance south of Iceland waiting to track SE into the UK. This it duly does overnight Saturday and by midday Sunday the SW has veered northerly over the UK and the next ridge is about to nudge in from the west. All, of course, subject to revision.

gfs_ptype_slp_eur3_25.thumb.png.fa0284ab1be9b77c3574cb9198399603.pnggfs_ptype_slp_eur3_29.thumb.png.2dfb86e16bf27fda7ee7a06ad97a429a.pnggfs_ptype_slp_eur3_34.thumb.png.e1877b41dc809a83ae4dfa8b718cfe81.png

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And just to emphasis that nothing is sorted from the middle of next week onwards the ecm takes a different approach to the gfs.

It continues to form a low on the front and has it west of Coruna by 12 Thursday. with the high pressure ridging over the top into the UK. But this ridge is quickly shunted south west as the trough to the NW phases with the one to the SSW and by 18 Friday there is a  tongue of low pressure and front running from Cornwall to Portugal with rain over the south west whilst the north is in strong WNW airstream courtesy of the large low pressure area to the north  The front crosses the southern half of England Saturday morning clearing the east coast by midday leaving the whole of the UK in showery north westerly.as once more the HP ridges in from the south west.

ecm_mslp_uv850_natl_8.thumb.png.23456ae57d40f31c2f6d64343f7d8c83.pngecm_mslp_uv850_natl_9.thumb.png.829418f3891465c80e59fdd2eb3c0b61.png

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Evening , if you look at the gfs and ecm plenty of opportunity for benign conditions and Frost will be the big issue first half of next week.. then models agree on a swathe of cold winds from Greenland  to fire up the jet stream and give us cold winds and rain at times , but nonetheless some sparkling sunshine in between and of course we have some stormy periods to look for in day ten perhaps.....:rofl: Actually a Proper Autumn Scene:D

ice cream man.png

ice cream manx.png

000_dv1630957_si.jpg

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The ecm still making rather more of the wave on the front at the end of next week and at 00 Saturday has the low over south west England with the band of heavy rain tracking north east into the North Sea during the morning  Thereafter it pushes the ridge in a tad quicker before the Atlantic assume dominance by Tuesday.

ecm_mslp_uv850_natl_8.thumb.png.3885617f1ef6334371f0e68adfee2efd.pngecm_mslp_uv850_natl_9.thumb.png.54f3507a0de3f8b66c366d0ae08a4a16.png

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21 hours ago, Geordiesnow said:

Is that the Pacific ridge you are alluding too? If so, then I certainly agree and don't quite get why people will be excited by this as I think the effects of cold weather on a UK perspective is quite minimal, yes the PV becomes disorganised but its useless for us if it does what you say it does and most of it heads into Canada and down the eastern seaboard and the other half heads into China leaving the UK and Scandinavia quite mild and deep cold air looking very far away from our shores. Of course, if the WAA heads up to the poles from the Atlantic side of the Arctic then things get more interesting as the PV will split into Scandinavia/Russia and Alaska and it suggests blocking over Scandinvia.

All that said though, the Arctic is too warm as it is and I don't see any benefits of a disrupted PV this early in the season and I rather see a rampant PV and stormy weather seeing as its still Autumn afterall, Sadly that is not the case at the moment as it look like we will be under the influence of fairly slack westerlies and fairly mild air so rather uninteresting outlook, not quite seeing much signs of a cold/dry start to November either really, if we get more amplification then maybe but most runs I seen dom't seem to back this up.

Yes, I was referring to the Pacific ridge and I agree with your thoughts. It doesn't seem to help us in the slightest. 

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It is the final day of BST today until March 25th which means from tomorrow's 00z's all models will update 1 hour earlier 

GFS 12z will start from around 15:30

ECM 12z  18:00 to 19:00

UKMO 17:00 to 18:00

All times are approx

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Yes November looking good. Shots of cold from the north, the continent getting a lot colder, and then that increasingly more southerly jet. Lots to be happy about! 

Edited by JBMWeatherForever
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Netweather GFS ImageNetweather GFS Image

Yes the 12 gfs run has my interest with some PM /  northerly outbreaks, but it still looks a bit mobile to me .The jet though is tring to dig south, certainly worth keeping an eye on.

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