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phil nw.

Model Output Discussion 4th Dec.2013-12z onwards.

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given the relatively low spread on ecm at day 10, there isnt going to be much to excite anyone searching for cold on the upcoming op runs. hopefully we will begin to see the fi jet sinking convincingly rather than meandering north and south by the time we get to saturday nights runs.

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given the relatively low spread on ecm at day 10, there isnt going to be much to excite anyone searching for cold on the upcoming op runs. hopefully we will begin to see the fi jet sinking convincingly rather than meandering north and south by the time we get to saturday nights runs.

 

It will be another 8 days before the time period I'm looking at shows on daily runs

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Solid agreement at day 6 between the ECM, UKMO and GFS...for nothing that is going to make the spine tinglePosted Image

 

ECM

 

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UKMO

 

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GFS

 

 

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Thereafter I would be suspicious of any premature suggestions to take the jet stream too much further southwards as, under present conditions with the polar vortex anchored at chez zonal hostilry, the models will be prone to over amplify the pattern beyond the reliable time period.(i.e the agreement indicated above)

 

Of course, a time will come at some stage when the profile over the Pacific improves and this will provide a more reliable indicator of amplification of the pattern.

 

In terms of background indicators, this is more likely towards week two and very unlikely sooner. It could be then that we see the bulk of the polar vortex start to shift a little further east with more of a -EPO profile over the Pacific and this leading to rather colder conditions most especially towards Northern Britain. But we remain at present quite some way from anything significant colder and the change to much more unsettled conditions gets underway from this weekend.

 

The deep depression on the ECM from this morning is not indicated on tonights output at day 7, but we should continue to watch for secondary developments spawning on the south western perimeter of the vortex gyre, where the temperature gradient is very steep, and then tracking eastwards towards the UK. Before then, NW Scotland in particular is threatened by very strong winds as soon as the latter part of this weekend

Edited by Tamara תָּמָר

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The CFS has been hinting at these eastily winds and very cold weather for a while , not sure why it keeps on with this idea. Clearly wrong!! Shame

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Looks like the ECM would go on to develop some very active lows from Newfoundland based on the temperature contrast showing there.

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Its just a normal British, default ,December weather folks... Alternating between colder and milder spells with the odd spell of stormy weather thrown in as well.! The lead up to Christmas could well have a lead headline as stormy, rather than wintry, although there will be some wintry stuff on the heads of the highest ground from time to time perhaps even in the south, but this will be fleeting......Posted Image Posted Image Posted Image

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GEFS are zonal all the way. That said they were showing high pressure all the way a few days ago.

Looks like a wild few weeks coming up. The question thereafter is MLB or HLB once this wild period ends?

Jason

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The CFS has been hinting at these eastily winds and very cold weather for a while , not sure why it keeps on with this idea. Clearly wrong!! Shame

Wrong? Please elaborate. We are only 2 weeks into meteorological winter!

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Wrong? Please elaborate. We are only 2 weeks into meteorological winter!

Wrong yes, we are not going to be in eastilys with cold and snow by Xmas like it was saying, yes Jan onwards may deliver.

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and yet only a few days ago some were saying we going to be stuck in the current patern for weeks on end. The cfs maybe wrong then so could the other models be also wrong.

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The GEFS 12z mean shows the north of the uk becoming rather cold as time goes on with a risk of snow on hills & mountains, for the south it's a little milder at times, especially early in the period but even the south has some colder days. Looking further ahead, it still looks like cold zonality could spread to the whole of the uk between xmas and new year with the jet alignment tilting more towards nw / se with increasing polar maritime shots. In the reliable timeframe there is a stormy spell heading towards n.ireland and scotland during the weekend with heavy rain pushing northeastwards, windy and unsettled in all other areas too. Looking through the GEFS 12z perturbations shows anticyclonic solutions being very thin on the ground, so the balance is firmly weighted in favour of a very unsettled and occasionally stormy outlook with large rainfall totals and hill snow across scotland in particular, good news for the ski resorts in scotland with sub zero temps at munro level (3,000 feet above sea level).

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It looks like n.ireland & scotland will have a stormy weekend with a double whammy of severe weather across the far northwest of the uk, the first on saturday and then later on sunday an even more severe storm with gusts of 80 mph plus. The Ecm 12z ensemble mean shows a progressively unsettled and windy outlook, the stormiest spells tending to be across the northwest corner of the BI with the best of any fine spells across the southeast corner. Temperatures up and down, more down than up across the north and the very unsettled spell is set to persist throughout christmas week with a seemingly never ending supply of atlantic lows which could eventually take a more southerly track and draw rather colder air further south in the process. In my opinion if we can't have deep cold and snow I would rather have this than weeks of benign boring stagnation and with such a disturbed outlook with rapid changes in airmass, the risk of cold incursions continues.

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Edited by Frosty.

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Its just a normal British, default ,December weather folks... Alternating between colder and milder spells with the odd spell of stormy weather thrown in as well.! The lead up to Christmas could well have a lead headline as stormy, rather than wintry, although there will be some wintry stuff on the heads of the highest ground from time to time perhaps even in the south, but this will be fleeting......Posted Image Posted Image Posted Image

 

 

this december, we have had (uk as a whole) snow, fog, frost and wind. we are forecast to have-  mild, cold, P.M incursions, heavy rain, storms, wintry showers, sunny spells..... etc.....etc..... models hinting at a change to.... colder snowy conditions?.... maybe.... who knows.

 

 

 

WE DON'T HAVE "DEFAULT " WEATHER!!!! Posted ImagePosted Image

 

 

 

(not picking on you in particular Anyweather, just keep hearing this term used too often)

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Don't rule out a white christmas, there are some wintry GEFS 12z perturbations on the big day and beyond,  arctic air digging southeast across the uk, especially the north.Posted Image

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Edited by Frosty.

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ecm ens means at day 10 has the uk at thicknesses 530 to 540 dam and uppers 0 to -2c in a strong westerly flow. naefs is somewhat less far south with the pfj so thicknesses are higher than 540 dam and only the scots are below the 0c isotherm. i have found naefs to be a generally better bet than ecm means at this timeframe.  ecm ens mean has tended to be at the extremes of the envelope at the relevant timescales. 

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Serious stuff if the LP sinks further SE

 

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Getting in the reliable timeframe

 

But...

 

Further afield in FI bonkersland

 

 

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Edited by Iceaxecrampon

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Overall not much change today in the models, very unsettled and stormy at times especially for the north.

 

The ECM was rather disappointing as it reformed the PV at T240hrs although it seemed overly flat upstream especially given comments from NOAA regarding the pattern in the eastern Pacific.

 

Initially the T144hrs outputs from the big 3 showed some interest, notable was more amplification towards the eastern seaboard of the USA and some ridging extending sw towards Svalbard, sadly this comes to nothing as the upstream pattern flattens out again past that point.

 

A mixed bag going forward, pretty dismal at times with a lot of rain especially to the nw, some sunnier interludes and showers in between, any snow looks reserved for the highest ground, perhaps a bit to lower elevations in the far north but any colder interludes are likely to be brief in nature.

 

In view of the output upto T240hrs I've decided to pull my horror rating and try and think positively so back comes the cold rating!

 

That stands sadly at a paltry 3/10

 

Snow rating 2/10

 

White Xmas the UKMO version 4/10 for northern areas, 3/10 for other areas., this might seem high given the model outputs but in this type of pattern you might get lucky and be in the more PM air that day, still the chance we could see a further southwards jet adjustment.

 

Overall its very much typical winter fare, frustrating for cold and snow lovers but we've been here many times before!

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Don't rule out a white christmas, there are some wintry GEFS 12z perturbations on the big day and beyond,  arctic air digging southeast across the uk, especially the north.Posted Image

Yes  - looking good.

 

Glad to break this near Tropical Sierra pattern - nothing can be ruled out but I fear for Lewis and Harris if next week comes off - that LP is perilously close and getting in a near reliable timeframe.

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Serious stuff if the LP sinks further SE

 

Posted Imagewindvector.png

 

Getting in the reliable timeframe

 

But...

 

Further afield in FI bonkersland

 

 

Posted Imageh500slp.png

Correct me if I'm wrong but that last chart screams potential doesn't it if a change to wintery weather is your thing. Just a shame its right at the far reaches of FI. Lets hope we see further similar trends on future runs. The met office update today also mentioned an increasing trend for colder weather to effect northern areas as we move towards the last third of December. Fingers crossed!

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I believe! If we all believe then it will happen Posted Image I might even subscribe to Mr Madden at this rate. Posted Image

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