Model output discussion 25th Jan onwards

[winterof79]

GFS at odds with the other models from as early as Friday.

http://www.meteociel.fr/modeles/ecmwf/runs/2014020400/ECM1-72.GIF?04-12 ECM

http://www.meteociel.fr/ukmo/runs/2014020400/UW72-21.GIF?04-06 UKMO

http://modeles.meteociel.fr/modeles/gfs/runs/2014020400/gfs-0-84.png?0 GFS

Exeter has this for Friday

http://www.weathercharts.net/noaa_ukmo_prognosis/PPVK89.gif?31415

[That ECM]

http://images.meteociel.fr/im/4491/ECH1-240_ova6.GIF

Maybe I am making the output fit my thoughts! But I have been talking of a change from mid month and this would be a good place to start from.

Prob gone by 12z just to make me look daft but I am encouraged by this.

[winterof79]

Trough disruption becoming the re-curring theme from ECM

http://www.meteociel.fr/modeles/ecmwf/runs/2014020400/ECM1-192.GIF?04-12

Colder uppers all the while mixing in

http://www.meteociel.fr/modeles/ecmwf/runs/2014020400/ECU0-192.GIF?04-12  could finally get interesting next week.

[bluearmy]

continuing the theme of ecm fi regarding a trend post mid month to colder with the upstream changes and euro height alterations against expectations. i wonder if the ens will begin to drift over with some consistency, run to run?

[Captain Shortwave]

To be honest I'm struggling to see the positives here, I mean yes it could snow.... after about another 6 inches of rain has fallen from successive fronts as the low pressure train travels west to east over the UK. It all looks very marginal and for many the wrong side of it. The 850s are completely mixed out under the upper trough so it's -2/-3s generally with dew points probably not looking that great as we can't get a cold surface flow establishing off the continent.

At this point in the season I rather have something to work with (a block) which can send some proper cold temperatures our way and what I certainly do not want is lots more rain. I mean many people are not going to celebrate if they get another half a foot of rain so that a sheep on top of a high hill in northern England gets snow.

For the next 5 days temperatures look above average, well at least in the south with temperatures of 8-10C

Edited February 4, 2014 by Captain shortwave

[Purga]

continuing the theme of ecm fi regarding a trend post mid month to colder with the upstream changes and euro height alterations against expectations. i wonder if the ens will begin to drift over with some consistency, run to run?

ENS just wet, wet, wet (especially the south!) and average temps no sign of cold so far really.

 

Edited February 4, 2014 by Purga

[Gibby]

Good morning everyone. Here is today's look at the midnight outputs from GFS, UKMO, GEM, NAVGEM and ECM for today Tuesday February 4th 2014, the text lifted from my website at http://www.norton-radstockweather.co.uk/Model-Analysis(2859336).htm

 

All models continue to paint a very disturbed period for the remainder of this week and the weekend for all areas as the never ending train of Low pressure crashing into the UK from the Atlantic continues. Today will see the first of these move up from the SW, deepening rapidly and bringing severe gales as well as heavy rain followed by showers though tonight and tomorrow. As this then moves slowly away North on Thursday a small but vigorous Low now looks like affecting the south later on Thursday and Thursday night with further heavy rain and gales in the SE before Friday sees yet another powerful depression move in from the SW to affect all areas over the weekend with further rain and gales for all over the weekend.

 

GFS then shows next week with very little improvements as further Low pressure moves up from the West or SW regularly with further rain and showers and strong winds. It may not turn out quite as wet though with some brighter intervals at times and there may be somewhat less wind too but it is unlikely that there will be any sustained dry and bright weather I'm afraid.

 

The GFS Ensembles remain very disturbed this morning with most if not all members showing a sustained period of rain and wind continuing in broadly West or SW winds around Low pressure areas moving in from the West throughout. Temperatures are likely to remain broadly close to average over the UK.

 

UKMO this morning starts next week with a deep low pressure area to the North of Scotland with a broad Westerly flow across the UK carrying blustery showers across the UK next Monday with the potential for further more prolonged rainfall looking likely too from the West over following days.

 

GEM in it's latter stages keep the UK under attack from multi centre low pressure areas keeping the trend for further spells of rain and showers, heavy at times very much alive next week too with average temperatures overall.

 

NAVGEM also shows a broad westerly flow to start next week with winds backing SW at the end of the run as something of a weak ridge dampens down some of the rain by Tuesday as a  weak ridge moves across from the West.

 

ECM is again unrelenting in it's prognosis of further deep Low pressure well in control of the UK weather next week too ending with Low pressure still sweeping onto the SW from the Atlantic with further gales and rain sweeping into the UK next Friday.

 

The ECM 9 and 10 Day Mean Charts remain unchanged in their prognosis that the likelihood of our weather will still be governed by Low pressure centred over or to the NW of the UK in 9 and 10 Days time with further copious periods of rain and showers likely for all in winds between South and West and average temperatures.

 

http://www.wetterzentrale.de/pics/Reem2161.gif

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

 

The Jet Stream remains one of the factors giving rise to such disturbed UK weather as it continues to blow very strongly over the Atlantic towards France and Southern Britain with little reliable indications supporting any major pattern change shown once more today.

 

In Summary today the weather remains extremely and exceptionally unsettled. For me it's the longest and most volatile Atlantic period of weather that I can ever remember and it is still looking relentless over all output issued this morning covering the next few weeks. So as a result I can only predict more rain, gales and flooding disruption to be expected over the next week or two with only very short drier interludes at times. The NE will probably see the best of these with the heaviest rains and flooding issues again most likely in the Southwest adjacent to the strong and disruptive SW winds at times. Temperatures overall will be close to average but there will be some colder slots in between the depressions when the showers could contain snow over the hills.

[East_England_Stormchaser91]

Yes, March last year was cold. Think people are missing the fact that there was sub -20 uppers sitting over Poland and Germany.

I don't even think we have any uppers even below -5 over the whole of Europe at present. It really is going to take something special if we see a repeat of March last year. The current outputs are not promising in my view tbh.

[Weather-history]

Yes, March last year was cold. Think people are missing the fact that there was sub -20 uppers sitting over Poland and Germany. I don't even think we have any uppers even below -5 over the whole of Europe at present. It really is going to take something special if we see a repeat of March last year. The current outputs are not promising in my view tbh.

I don't think the uppers over Eastern Europe are really relevant now to how cold March may or may not turn out. We could get a wintry March via northerly flows, in which case European uppers are irrelevant. It could happen that there are very cold uppers at the end of February when they weren't at the start of February. There is too much water to flow under the bridge. And I add that no one knew how cold March last year would turn out even at the start of the month. Having said that I don't think March will be a repeat of last year but it doesn't have to be. Edited February 4, 2014 by Weather-history

[Frosty.]

The Ecm 00z op run shows colder uppers becoming established from T+144 hours onwards with 528 dam thicknesses covering most, if not all of the uk which means we potentially have the best chance of seeing snow and ice making the headlines during next week instead of torrential rain and storm force winds. If this trend locks in, and the signs are promising from the gfs and ecm 0z, next week would be the most wintry week of the winter so far with the snow line descending to lower levels as time goes on as colder polar maritime air mixes with increasing amounts of trough disruption.

[johnholmes]

Can one of you that use the term 'trough disruption' please explain just what you mean by this please?

A genuine question as I am a touch lost as to just what you are meaning.

thanks

 

Is this what you mean?

the process whereby part of an upper trough moves 'forward' (usually west to east), leaving a portion of the old trough behind. (See Anticyclonic and Cyclonic trough disruption.) 

 

another one

Anticyclonic trough disruption

If the northern (southern in the southern hemisphere) portion of an upper trough moves forward and warms out, leaving a quasi-stationary cut-off low in the base of the trough, the process is described as anticyclonic trough disruption - because the net result is a strong build of pressure/new high cell formation behind the retreating trough.

 

and the other type

Cyclonic trough disruption

The southern (northern in the southern hemisphere) portion of a trough advances, perhaps developing a cut-off circulation, and slowly warming out, whilst the opposite (residual) portion of the trough becomes quasi-stationary, maintaining a cyclonic pattern at the surface.

 

which one of these are you talking about.

 

I will go and see if I can find either of them, must be getting old.

 

 

Edited February 4, 2014 by johnholmes

[MR EXTREMES]

well the hemispheric charts show what cc said lastnight it could well turn out to be a re run of last spring.

heights building into siberia finland watch this progress futher over the coming days.

 

the vortex is having one last redbull then the stocks run out and we see a colder end to feb.

this is the t144 chart now watch tonights and tomorrows to see if we can build on this....

[Summer Sun]

The GFS ensemble is now showing an end to these deeps lows of the Atlantic albeit well into FI at this stage it does stay unsettled but probably not as much rain around in the south and south west as of late

 

Edited February 4, 2014 by Summer Sun

[johnholmes]

re my post above and it is a little sad that no one that has been using the term I asked about has replied but then maybe they are not around at the moment. Please drop a reply when you read it.

Until then why not simply say, having looked at various 00z GFS outputs using the excellent play back system on Extra, 1000-500mb and 850-1000mb thickness charts and surface msl and dewpoint that illustrate what the GFS model is suggesting will happen=

After the major low over the weekend shifts into the North Sea then colder air, at the surface and at higher levels, will move out from the main Canadian trough/vortex, over the UK. This is predicted to last until about 11-12 February when the model suggests a return to values similar to what we have had over the last few days. Much longer but is it not more easy to understand for a lot of folk?

[Nick L]

 

Can one of you that use the term 'trough disruption' please explain just what you mean by this please?

A genuine question as I am a touch lost as to just what you are meaning.

thanks

 

Is this what you mean?

the process whereby part of an upper trough moves 'forward' (usually west to east), leaving a portion of the old trough behind. (See Anticyclonic and Cyclonic trough disruption.) 

 

another one

Anticyclonic trough disruption

If the northern (southern in the southern hemisphere) portion of an upper trough moves forward and warms out, leaving a quasi-stationary cut-off low in the base of the trough, the process is described as anticyclonic trough disruption - because the net result is a strong build of pressure/new high cell formation behind the retreating trough.

 

and the other type

Cyclonic trough disruption

The southern (northern in the southern hemisphere) portion of a trough advances, perhaps developing a cut-off circulation, and slowly warming out, whilst the opposite (residual) portion of the trough becomes quasi-stationary, maintaining a cyclonic pattern at the surface.

 

which one of these are you talking about.

 

I will go and see if I can find either of them, must be getting old.

 

 

 

I would also be interested in someone clarifying this! The term (among many in here) has had me scratching my head for a while.

[joggs]

Cant speak for others who use the term trough disruption,but i understand it as your last suggestion John.Although i dont use the term myself.

[MP-R]

re my post above and it is a little sad that no one that has been using the term I asked about has replied but then maybe they are not around at the moment. Please drop a reply when you read it.

Until then why not simply say, having looked at various 00z GFS outputs using the excellent play back system on Extra, 1000-500mb and 850-1000mb thickness charts and surface msl and dewpoint that illustrate what the GFS model is suggesting will happen=

After the major low over the weekend shifts into the North Sea then colder air, at the surface and at higher levels, will move out from the main Canadian trough/vortex, over the UK. This is predicted to last until about 11-12 February when the model suggests a return to values similar to what we have had over the last few days. Much longer but is it not more easy to understand for a lot of folk?

 

I haven't used the term but I always thought it was when a trough fills or dissipates more or less in situ when the energy supply is cut off. I also hope somebody with a bit more knowledge can answer this one.

[nick sussex]

A few signs of life overall today in terms of a chance for something a little colder, the main point of interest is the Canadian PV edging further to the nw.

 

The thermal gradient over the ne USA weakening and so a better chance to develop a more favourable pattern, however theres still no sign of a clear signal to bring in deep cold uppers, the ECM ensembles whilst showing a small improvement are still pretty underwhelming.

 

It's  a start at least but after months of garbage chasing marginal snow is really not going to appease disgruntled cold and snow fans in here!

 

We'll have to see whether the models can continue to edge the jet further south and whether we can find a decent cold pool that could be advected back into the UK.

Edited February 4, 2014 by nick sussex

[Gael_Force]

My understanding is that it is when the base of a trough cuts-off allowing an easterly flow over the UK rather than the long fetch returning polar maritime we are currently seeing.

[Mucka]

Trough disruption.

 

 

Not been on today but that is a decent example of how I would use it.

Edited February 4, 2014 by Mucka

[johnholmes]

re the trough disruption, essentially there are two types, one is called anticyclonic and the other cyclonic, the definition is in my post above.

As with some other terms they are used rather liberally by some folk. I prefer to use simple terms that everyone understands.

Edited February 4, 2014 by johnholmes

[Mucka]

Yes it is used rather liberally and quite loosely no doubt, as with much of the terminology used in here but I'm not sure I would have to preface trough disruption with cyclonic in the above example for people to understand what I was talking about. (The forum is not just for those with an academic meteorological background and caters for all levels - where people are wrongly using a term or misinterpreting a chart they usually get a gentle nudge in the right direction from other members which keeps the forum  popular and friendly, people shouldn't be afraid to post),

If I am using it incorrectly or people don't understand what I'm referring to I would personally be quite happy to change my ways.

[legritter]

Havent posted in a while ,but been watching in total amazement at our current stormy spell which as now been with us for Seven weeks or there abouts .about the same time scale as some of our notable severe winters but in a different weather type .looking at the Models and Data it looks like we enter slightly different territory next week with some colder uppers and colder temperatures at the surface .but its at a range that could change but still i think a fair possibility .A good post from Johnholmes regards Trough Disruption ,the weather is very complex with loads of physical things happening ,but for many the term is quite often used when a trough is acted upon by other atmospheric conditions ,and of course quite loosely talked about when a trough approaches the Uk from the west or  s west and runs into colder continental air hense bringing us our magical snow ,But it would be nice if we all stuck with the same definition for learning reasons ,but this Forum needs discussions like this as its all part of the learning experience.So interesting times a head and who knows where we could be this time next week ,cheers 

[EML Network]

Are people really looking at the charts and hunting for cold and snow ??

 

Surely there's no point when the Jet is powered up like it is ?

 

One of the wildest periods of weather for the channel coasts coming up than has been experienced for some time.

 

I don't even want to think about what sort of images we'll be seeing in the newpapers and on TV by the time we get around to this time next week, but I should imagine that it's not going to be very pretty .

 

Unless you happen to be a duck or a fish, or someone who sells sandbags or dinghy's !

[johnholmes]

The main reason I raised the topic was that I could not see where the trough disruption quoted by several posters this morning was occurring?

Does anyone else see trough disruption in the GFS output?

Please show me as I am honestly unable to see just where this is happening-that is all I am asking.

 

and to answer mucka, it is the loose and at times incorrect use of some terms that is misleading. Why use the term if others are not sure what you are saying?

Edited February 4, 2014 by johnholmes