Model Output Discussion 17th Dec.2013-12z onwards.

[R.P. McMurphy]

 

Those charts are often innacurate Glenn,

 

If I cannot base it on charts or data, how does one predict the weather?

 

Is it the old lick of the finger and place it in the air trick?

 

Ahhh Yes, Cold & Snow....  

 

Edited December 18, 2013 by Glenn W

[legritter]

Model watching is always going to be a painfull process especially if you are looking for your type of synoptics to turn up .but i would say to new members ,Read the posts of some of the regular posters ,pop into the learning area and look at past events in history ,history in meteorology does not always mean things repeat themselves but you can learn fascinating facts and apply it to your learning skills .Well im pretty sure looking at all current data and models that the next 10 days or so will be full of interesting weather and each day giving the Forecasters a new challenge as new features pop up in a very mobile and gradually turning colder weather pattern .BUT cast your mind back to friday the 6th of December ,and as i said last week on that date it was all talk of Euro tripe etc ,I for one had the Euro blues ,but look where we are now ,and where we could be two weeks from now in what is an eternity in forecasting time .Well GFS is in the kitchen cooking up ,and ECM tonight could lets hope be a good one .

[A.J]

Well, I make it around 5-5 in the battle between Shed & Glenn......No injury time I'm afraid chaps, an honourable draw, unless you wish to fight to the death via pm? 

 

Ok, in the short term, the Met's Euro 4k model (now available on weatheronline) showing a decent signal for snowfall for parts of the west country and central southern england, interesting to see if the NMM hi-res 12z output concurs (around 5pm) 

[Paul]

Please don't reply to this in here as we'll end up way off topic, but for those wanting a more seasonal theme, the Xmas skin is now available for the forum:

http://forum.netweather.tv/topic/78800-christmas-skin-now-available/

[Cold Winter]

Yes interesting weather overnight and tomorrow. Some very heavy rain overnight moving east, cold air digging in behind with frequent snow showers across western Scotland. Then tomorrow some models are picking up on the idea of snow down to fairly low levels (above 100m) for some areas further south.

 

The Euro4 model (now available on weatheronline.co.uk) highlights a potential area of snow tomorrow evening across from S Wales, the Midlands and Lincolnshire pushing east, possibly settling over higher ground. Snow is possible down to low levels in the heaviest areas of precipitation (pink colours on this map below).

 

 

 

Meanwhile the NAE has the area of rain/snow extending a bit further north:

 

 

Edited December 18, 2013 by Cold Winter

[Paul]

Just for info, the Metoffice Euro4 model isn't actually 4km resolution, it's 12km - the 4 in the name is for another reason (not sure what).

[Tamara]

 Hello Egret,

The thermal gradient is likely to reach its peak across the North Atlantic over the next 10 days, hence the powering up of the Atlantic storms. The current synoptics across Europe and including the UK have been spot on ( rather mild ) with the modelling showing a rise of pressure across Europe with the jet deflected poleward in its seasonal  prediction.. A change of the course of the low pressure systems southwards are projected in January with a consequence rise in pressure over the Arctic. Confidence from our expects remain high for this to happen and I cannot argue with their advice, but is always open to be questioned.

 

c

Hi C and thanks for your post earlier

 

I think the big question is whether any southward migration of the jet stream is to be accompanied by a rise of pressure over the arctic.  Indications are that the jet stream perhaps coming south is a response to a progression of secondary lows spawning further and further south from the main core of the vortex over Canada and Greenland and may be a consequence of the possible factors that bluearmy outlined earlier, and as there is a slight eastward adjustment of the polar vortex. However, the vortex itself is unlikely to blink or be effectively disturbed to allow arctic blocking until seasonal wavelengths change and tropospheric wave breaking feedback patterns hopefully become more effective later in January and more especially into February. But that is a long long way off and well beyond the realms of this thread  I and many others would obviously like the suggestions you have relayed to be correct of course and it happens sooner rather than later !

[Cecil Hogmanay Melchett]

Tomorrow looks interesting GFS/NAE bring a pretty intense area of precipitation across  the NW of England and yorkshire,will need watching esp so for elevated routes.

Edited December 18, 2013 by happy days

[nick sussex]

Better Arctic profile on the GFS 12hrs run, note the area over northern Greenland, also the jet is further south digging into the mid Atlantic. You need the low over the UK as far south before it phases with the low coming out of the ne USA.

Edited December 18, 2013 by nick sussex

[Ali1977]

Xmas low pressure digging much further south on 12z, hopefully this could assist snow prospects!

Edited December 18, 2013 by Ali1977

[shaky]

Tomorrow looks interesting GFS/NAE bring a pretty intense area of precipitation across  the NW of England and yorkshire,will need watching esp so for elevated routes.

big disagreement with the ukmo4 model then which brings most of the snow across the midlands!!crazy to havr this kind off disagreement within a a short time frame. Well at least the ukmo4 model will be tested properly over the next 24 hours lol.

[Ali1977]

Stronger high pressure over Greenland looking like helping lows track further south..

[swfc]

12z looks ok on the nh chart at 126 hr mark ie weakening pv and pressure rise towards greenland.The eastern seaboard then fires the pv back up via its devil spawn low yet again!!!plus this euro high is a pain and needs nuking!!!

Edited December 18, 2013 by swfc

[Cecil Hogmanay Melchett]

Better Arctic profile on the GFS 12hrs run, note the area over northern Greenland, also the jet is further south digging into the mid Atlantic. You need the low over the UK as far south before it phases with the low coming out of the ne USA.

Hmm didn't really go to plan Nick!

[gottolovethisweather]

One thing this current pattern does do is that it makes us coldies endlessly search for changes further down the road. For me, the more immediate timeframe is still often of interest, as I stated in here just three days ago.

 

http://forum.netweather.tv/topic/78671-model-output-discussion-4th-dec2013-12z-onwards/?p=2862368

 

Now I will post up comparative charts from that post to where we were to now, just three days on.

 

On the 15th December, the GFS 6z indicated the following 850s & SLP for today's depression at 1800 hours.

 

 

Now, today the GFS 12z shows the following situation at t+6 hours i.e. 1800 hours.

 

 

All in all a similar situation but with a deeper depression than previously forecast in evidence. Some twelve hours, later three days ago the following was hinted at for 0600 hours tomorrow morning.

 

 

The likely reality now shown by the GFS 12z in terms of 850s & SLP for 0600 hours tomorrow morning is.

 

 

By this timeframe the uppers projected are marginally higher than previously indicated which could be of concern for those expecting snow further South. Come midday tomorrow some three days ago the predicted situation was as follows.

 

 

Now according to the GFS 12z the predicted 850s & SLP for midday tomorrow are as follows.

 

 

Once again, come that time of day the wintry mix will likely simply be nothing better than wet snow given the uppers I would imagine, however............ By 0000 hours on Friday morning, the 15th December 6z run originally suggested this.

 

 

According to the GFS 12z, 0000 hours on Friday morning in terms of 850s & SLP now looks like this.

 

 

By the time of the last chart if there is any precipitation away from the SE corner, I would expect it to be largely falling of snow.

 

In summary, the next 36 hours look pretty lively with everything from snow, sleet, gales, hail, thunder and flooding all in the mix and of course, it doesn't stop there.

 

Remember my NH Jetstream watch, this was the predicted scenario from the GFS 6z two days ago for Tuesday 24th December at 1800 hours.

 

 

Now the watch is into t+150 hours and counting, see below.

 

 

The above most definitely shows a completely different Jet alignment, so still all to play for come Christmas week. Let's now compare Monday's 6z run with the NH Jetstream and where it is now predicted to sit over the UK on Christmas Day.

 

Monday 6z showed this.

 

 

Via today's GFS 12z the NH Jetstream on the big day now hints at the following alignment at t+174 hours.

 

 

Some similarities with the last chart to that of its predecessor but the best thing about it is where the Jet wants to go as we head into the final days of December and that is further and further South.

 

One thing to finally note is that my analysis comes courtesy of the GFS output only, we probably wished we had more tools in our toolbox, so with the UKMO giving a bigger thumbs up   to the immediate timeframe in terms of snow things are certainly better than most would have expected. To add to this, us coldies can also hope that the charts will perhaps start showing further wintry synoptics in the days forthcoming and I would suggest my next watch period would be Christmas/Boxing Day.

Edited December 18, 2013 by gottolovethisweather

[That ECM]

Hmm didn't really go to plan Nick!

http://images.meteociel.fr/im/2327/gfsnh-0-360_jcu0.pngWent to plan perfectly. Did you not see this coming??!!!

[swfc]

http://images.meteociel.fr/im/2327/gfsnh-0-360_jcu0.png

Went to plan perfectly. Did you not see this coming??!!!

well id put my morgage onthat  being gone on the 18z and i also didnt see it coming !!

Edited December 18, 2013 by swfc

[Cecil Hogmanay Melchett]

http://images.meteociel.fr/im/2327/gfsnh-0-360_jcu0.pngWent to plan perfectly. Did you not see this coming??!!!

nope

[MR EXTREMES]

the gfs in fi really is a close call we need the part of vortex to shift a little futher west and the other futher east as the gfs is trying to send a ridge into Greenland from the south on the western part of the alantic.

 

its so close but there could be if fi is right which I will say most likely not because I don't want to hopecast but the models are so close with this development as it stand though is the jet wont allow a futher push into southern Greenland as the part of the vortex in Canada is not allowing this but as nick sussex says the gfs is showing tiny signs of a pattern change.

 

but that's much later in the outputs.

for the hear and now its looking stormy with some surprises popping up futher west northwest and midlands north could well see something of a wintry nature.

 

and although there has been the model roller coaster from hell over the last 6 weeks or so there is now something for a lot of coldies can look forward to maybe some will be disappointed I for sure don't expect to see anything but some will which is better than the blow torch sw flow showing several days ago.

 

it wont last to long but its a start.

we really need to se the jet vortex and lower heights into Europe to play ball for jan but I do think as tamara suggested we might be waiting awhile yet although interesting charts might just keep us watching with an keen eye.

[Cumulonimbus Tower]

A new model for people to use now is the UKMO euro 4 which is now available here http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=euro&MODELL=euro4&MODELLTYP=1&VAR=prec&HH=3&BASE=-&WMO=&ZOOM=0

Well it will be interesting to compare the track of the minor feature tomorrow with the predicted NAE and Euro4 tracks as they have a signifigant diference between them. Less shower activity for the coasts shown on Euro4 too i think....

[Summer Sun]

Christmas eve still looking very windy especially in Scotland

 

 

Christmas day sees a welcome break from the strongest winds

 

 

Before the next low arrives on Boxing day

 

Edited December 18, 2013 by Summer Sun

[MR EXTREMES]

the gem out put also sends the jet futher and futher south

[Mucka]

Vortex doesn't look so mean and indomitable on this lates GEM chart. 

 

[MR EXTREMES]

infact the jma gem gfs and gefs all send the jet south most are just through the English channel this could be a turning point.

[Mucka]

infact the jma gem gfs and gefs all send the jet south most are just through the English channel this could be a turning point.

 

Shhh. 

 

A long way to go yet but I like the positive vibes (jinx  )