Model Output Discussion - 12th December Onward

[Great Plum]

Ensembles confirm that the 18z op was one of the warmest:

http://www.netweather.tv/index.cgi?action=charts;type=ens;sess=

Does seem clear that we will have some very warm air for the time of year over much of the country in the week before Christmas and then maybe a cooler 'blip' around the big day itself...

[The Northern Ramper]

True Nick and worth pointing out the scandi high at 180hrs, or rather lack of one!!

I recall GP saying it would be a big feature in mid Jan.

Let's hope so because it aint there in late Dec

You understand that January is a different month to December, yes?

[Duane S.]

Hmmm 18z not a pretty sight... My pub run was far better.

Yesterday's GFS 12z was a tease, maybe a taster of things to come, just a bit too early. Better signs aloft of vortex disruption, you could see things going the way of early Jan 85 with a lovely arctic high forming as we see a proper split and major retrogression up through the UK into Western Svalbard. From there are on it would likely continue aka early 85. Do think we will have to endure some mild dross for a while later on to get there though.

[ZONE 51]

Remember the DWD? thats seems to have disappeared.. great loss indeed !

http://www.dwd.de/ - is this the one you mean?

[KTtom]

GFS Ensembles pretty much sum it up this morning. Expect absolutely anything after T+60! Don't think I have ever seen such inconsistancy.

[Nick F]

To me there looks to be fairly good consensus between GFS and ECMWF into the medium range of a strong westerly regime driven by low heights to the N and NW and a fairly strong Azores ridge, as shown by the 00z 8-10 H500 comparisons.

A little uncertainty on how far north the Azores high will influence southern areas, but it does look to be more unsettled the further north one is in the UK, but unsettled weather affecting the south at times too. There does look like some scope for some brief colder NW'erly incursions, but not enough amplification in the strong zonal westerlies to allow anything more.

Although it doesn't look particularly wintry away from the northern hills in the run up until Xmas for now, at least it doesn't look like prolonged southwesterlies are on the cards, though 00z ECM does show +10C T850s across soouthern Britain next Friday before colder Pm air returns quickly for the weekend.

[bluearmy]

i note the appearance of high heights other side of the pole on ecm T240. of course it means nothing other than the fact that they have been allowed to get there by the model ......................

Edited December 16, 2011 by bluearmy

[chionomaniac]

i note the appearance of high heights other side of the pole on ecm T240. of course it means nothing other than the fact that they have been allowed to get there by the model ......................

When looking at the vortex profile that is not a surprise to see heights rise there first as the vortex displaces towards Siberia.

[johnholmes]

To me there looks to be fairly good consensus between GFS and ECMWF into the medium range of a strong westerly regime driven by low heights to the N and NW and a fairly strong Azores ridge, as shown by the 00z 8-10 H500 comparisons.

A little uncertainty on how far north the Azores high will influence southern areas, but it does look to be more unsettled the further north one is in the UK, but unsettled weather affecting the south at times too. There does look like some scope for some brief colder NW'erly incursions, but not enough amplification in the strong zonal westerlies to allow anything more.

Although it doesn't look particularly wintry away from the northern hills in the run up until Xmas for now, at least it doesn't look like prolonged southwesterlies are on the cards, though 00z ECM does show +10C T850s across soouthern Britain next Friday before colder Pm air returns quickly for the weekend.

yes Nick, all 3 have trended over the past week for the type of chart you show from ECMWF-GFS this morning.

[shedhead]

After what has proven to be a massive damp squib re todays severe weather, all eyes turn to the future and as Phil says a milder interlude now looks inevitable. The north certainly looks set to remain in something

rather cooler than the south and giving the right timing a few wet flakes appear possible on the big day, especially over high ground. Looking further ahead, I'm yet to be convinced there are too many signal for a pattern change, hopefilly these will begin to a appear across the remainder of Dec.

[karyo]

The ECM hasn't updated on Netweather or Meteociel!

Karyo

[nick sussex]

The ECM hasn't updated on Netweather or Meteociel!

Karyo

Unfortunately it did on wetter.... I would have been happy for it not to show up today given its output!

However looking at the ECM ensemble maps there are quite a few more amplified solutions at 168hrs with less influence from the Azores high.

http://www.ecmwf.int/samples/d/inspect/catalog/samplers/banner/mean_sea_level_pressure_and_temperature_at_850hpa!168!pop!od!enfo!enplot!2009112700!!/

[tcc]

After what has proven to be a massive damp squib re todays severe weather, all eyes turn to the future and as Phil says a milder interlude now looks inevitable. The north certainly looks set to remain in something

rather cooler than the south and giving the right timing a few wet flakes appear possible on the big day, especially over high ground. Looking further ahead, I'm yet to be convinced there are too many signal for a pattern change, hopefilly these will begin to a appear across the remainder of Dec.

Why is it a damp squib? Do you mean in terms of wind? Or lack of snow in your backyard? It's been snowing here at Gatwick for the past two hours which has been a fantastic surprise and more than I hoped to see this month! So I wouldn't call it a damp squib based on what's falling out of the sky!

[Downburst]

Apart from a brief mild spell next week the pattern remains very polar maritime influenced so we know what to expect, a festive snow shower this morning after a heavy frost, 2nd snow this month and that is amazing here. We are running 1.5 C below average for the month, reflecting the general West to NW West flow with cold fronts moving in behind quick moving lows.

Very interesting pattern and far better than most years.

There is a lot of manic demands for Heights here there and everywhere and outright condemnation of a model run if it doesn't have it. Meanwhile the winter passes away. I encourage people joining to start with the ECM, 240 hours or 10 days is absolute max one can trust and stick to that.

[nick sussex]

The longer range ECM ensembles certainly suggest a mobile pattern , the main clustering from the 24th is not indicative of a strong Azores high pushing into Europe and suggests a more average west to east flow with still chances for the odd PM incursion for the UK.

http://www.weerplaza.nl/15daagseverwachting/default.asp?type=eps_pluim

Now that the models have flattened the pattern out, we wait to see whether they over reacted and if we can see a bit more amplification upstream.

[Summer Sun]

A mild ish New Year

http://www.wetterzen...s/Rtavn3842.png

Unsettled christmas day according to GEM

http://www.wetterzentrale.de/pics/Rgem2281.gif

Edited December 16, 2011 by Gavin D

[Ruzzi]

A mild ish New Year

http://www.wetterzen...s/Rtavn3842.png

Unsettled christmas day according to GEM

http://www.wetterzen...cs/Rgem2281.gif

New years is still over 2 weeks away. I'll eat my own face if that's what the chart actually looks like on new year's day

[bluearmy]

The longer range ECM ensembles certainly suggest a mobile pattern , the main clustering from the 24th is not indicative of a strong Azores high pushing into Europe and suggests a more average west to east flow with still chances for the odd PM incursion for the UK.

http://www.weerplaza...?type=eps_pluim

Now that the models have flattened the pattern out, we wait to see whether they over reacted and if we can see a bit more amplification upstream.

no time for a detailed post but the naefs far off fi draws the higher anomolies back into the atlantic from our south. continuation of the current pattern as you posted ????

[BLAST FROM THE PAST]

So the 'storm' finishes as an LP running up the channel with main LP top our NNE and colder conditions seting in. IMO this is as good/cold as it gets next few days for Dec but some further potential stormy weather over Christmas period. V happy thus far the way Dec has gone,

I think GFS nad ECM show a further mixture of cool and mild and cool etc etc GFS showing extremely mild set up for around New Year.? ?

BFTP

[Methuselah]

Aye, as the models have consitently shown (and continue to show) December looks like being the traditional 'mixed bag'. So yes, and 'average' month was a brave forecast...

[Bobby]

no time for a detailed post but the naefs far off fi draws the higher anomolies back into the atlantic from our south. continuation of the current pattern as you posted ????

True, looking at the ensemble averages it looks like the Azores high will nudge into the south for a few days before more unsettled fairly zonal weather spreads across the country. Probably unsettled across the North throughout.

Edited December 16, 2011 by Barb-

[Glacier Point]

The trend in the modelling around day 8 looks to be taking the mean ridge position further west allowing more the jet to take a more west - east trajectory. Interesting as it goes against the grain from recent solid model concensus to develop the ridge more towards the UK and France.

This is exactly the same as the most recent deep upper trough, where modelling was going (with strong ensemble mean support) for a ridge and this rapidly turned around.

Are we dealing with a second model bias here following on from the horrific job the models have done with the NAO this November and December ?

I'm very interested in the Azores ridge retreating westwards and a more NW-SE tilt to the jet developing as we hit January, so we're at the very outer limits of the modelling.

[BLAST FROM THE PAST]

The trend in the modelling around day 8 looks to be taking the mean ridge position further west allowing more the jet to take a more west - east trajectory. Interesting as it goes against the grain from recent solid model concensus to develop the ridge more towards the UK and France.

This is exactly the same as the most recent deep upper trough, where modelling was going (with strong ensemble mean support) for a ridge and this rapidly turned around.

Are we dealing with a second model bias here following on from the horrific job the models have done with the NAO this November and December ?

I'm very interested in the Azores ridge retreating westwards and a more NW-SE tilt to the jet developing as we hit January, so we're at the very outer limits of the modelling.

So am I Stew. Sorry for one liner but what else is there to say in answer to that. My post 689 very much supports that train of thought so I'm intrigued that GP has these thoughts.

BFTP

Aye, as the models have consitently shown (and continue to show) December looks like being the traditional 'mixed bag'. So yes, and 'average' month was a brave forecast...

Models have been very up and down pete, not consistent

BFTP

Edited December 16, 2011 by BLAST FROM THE PAST

[KTtom]

The trend in the modelling around day 8 looks to be taking the mean ridge position further west allowing more the jet to take a more west - east trajectory. Interesting as it goes against the grain from recent solid model concensus to develop the ridge more towards the UK and France.

This is exactly the same as the most recent deep upper trough, where modelling was going (with strong ensemble mean support) for a ridge and this rapidly turned around.

Are we dealing with a second model bias here following on from the horrific job the models have done with the NAO this November and December ?

I'm very interested in the Azores ridge retreating westwards and a more NW-SE tilt to the jet developing as we hit January, so we're at the very outer limits of the modelling.

...and as a concequence of this, higher pressure building to the North East during the start of Jan?

[Bogman]

So, in lay-mans terms.......................?