Model Output Discussion - 23rd Jan - 12z onwards

[Longshanks]

Yep. North Wirral - the very start of the Cheshire gap - temperatures again aren't advertised by any agency as dropping below a day time maximum temp of 4/5 degrees C on any coming day in next week? Don't know how much grandiose delusion and hope casting is involved in the clamour for registering a cold end to winter -seems more about psycho-sensitising beliefs and somatic thinkings unfortunately - hope I'm wrong.. ? Right in the firing line, we've not progressed beyond rain and a hail shower - so far. Quite bizarre stuff. Anyhow should be good conditions for wintery fell running this weekend in Wales - it's been a good season for us so far!

[West is Best]

A very sobering 18z it must be said. New signal? Rouge run? Tune in for the next instalment at 4:15 am

 

It's because after 11 successive operationals below the ensemble mean sooner or later an operational had to break. We need to see the scatter to see where this one sits with regards to the others, and then view the likely scenarios from there. For the last 3 days the ensembles have shown far too many milder members from 03rd Feb onwards for comfort, and particularly seeing the operational below the mean every time has been of concern (especially when the 12z ECM trended that way today).

 

Let's see what the 0z's bring tomorrow.

Edited January 28, 2015 by West is Best

[Banbury]

I think the concerning thing is that the gfs has picked up a new trend for next week to flatten that high and bring the

Atlantic back. Whether it's FI or not the ensembles have been hinting this.

But the good news is that in the reliable it's looking nice and cold with rain/sleet and snow, proberly nothing for my area but no change there.

Really?? surely a trend is when something starts to re-appear?? on the previuos runs a block was shown...................just one run

[Paul_1978]

A very sobering 18z it must be said. New signal? Rouge run? Tune in for the next instalment at 4:15 am

Hmmm, well only 6 hours ago we had people bashing one off about FI charts, so with these kind of changes between runs, there's no need to worry I'd say.

[Hotspur62]

18z in FI is quite frankly, gross

 

GFS FI.png

Doesn't look good but it is only one run and as you say it is FI.As Tamara discussed earlier there are building blocks in place so don@t be too downhearted just on this run. As we know GFS is too progressive pushing things Eastwards anyway. If this time tomorrow the next 3 runs are all saying the same thing and other models follow it maybe a different story but I think that is unlikely to happen.

 

Keep the faith!!  

[ITSY]

just a brief one from me as off to bed now, but no reason to be disheartened tonight. Snow wise the offers are actually an upgrade in the short-term term with events taking place tomorrow, overnight thurs/Fri, Friday during the day (providing uppers allow) and then a more organised front next Tuesday which, contrary to some observations, still takes shape to the tune of 10mms of rain/10cms of snow for some.

 

All conjecture, all could be wrong, but as we take all possibilities into account we should remember not to throw the baby out with the bath water. Tonight's offering offers something snowy for most of us over the coming 5-6 days - eyes should be peeled to the Beeb, Meto and the Fax charts for genuine information on features and precipitation etc.

 

Edit: things appear very quickly in these setups. Only yesterday I said there was nothing on offer for the East - this is no projected for less than 48hrs away:

 

 

It may well be gone in the morning, but it proves the point somewhat. Unstable cold air can produce things at short notice. Lets wait and see how this one turns out...

Edited January 28, 2015 by ITSY

[BurwellWeatherWatch]

No chance of pinning much detail onto the next week and it'll just be a case of enjoying whatever happens. Various variations on a theme but it should be cold (and potentially snowy in places) for at least a week. Despite the 18z tonight, the trend is still to maintain that into next weekend - but what will be will be.

I don't quite understand why certain members got incredibly excited about a puff of sleet into the North Midlands back on Boxing Day, and then seem to be utterly despondent about a week of virtually nationwide cold, and seeking every opportunity to find a forecast that ends it - but each to their own!

Looking forward to the next week and great that it is occurring in the thermal depth of winter. Would be great if we could get a March 2013 synoptic in Feb 2015!

[bluearmy]

Not a very convincing warm up! Probably quite a few blocked runs in there, given the low av wind speeds on the wind graph

[Frosty.]

Too many knee jerk reactions to a pub run in FI..unbelievable. Hi res is plenty cold enough with a risk of snow showers and plenty of sharp penetrating frosts. In the short to medium term nothing has downgraded, we have the potent polar maritime and by the end of this week we will have an even colder Arctic maritime blast and it wont be a straight forward wishbone effect, there will be troughs embedded in the cold flow too..lots to be pleased about in my opinion!

Edited January 28, 2015 by Frosty.

[nick sussex]

I see the GFS 18hrs run continues with its flat shortwave over the eastern USA, flat shortwave there equals a more progressive pattern downstream.

 

I commented on this earlier re both the GFS and ECM, you'll see the big difference this makes to the UK by comparing the UKMO at T120hrs and the GFS 18hrs run to T114hrs:

 

GFS 18hrs run to T114hrs:

 

 

UKMO 12hrs run to T120hrs:

 

 

The latest from NCEP New Hampshire forecast:

 

A MORE VIGOROUS SHORTWAVE DIVES INTO THE EASTERN STATES SUN NIGHT
AND MONDAY. MODELS CONTINUE TO STRUGGLE WITH REGARDS TO THE
AMPLITUDE OF THE TROUGH AND THE CORRESPONDING SURFACE LOW AND TRACK.
THE LATEST 28.12Z OPERATIONAL RUNS OF THE GFS AND ECMWF NOW ARE MORE
PROGRESSIVE AND SHOW A WEAKER SURFACE LOW AND WELL EAST OF THE
BENCHMARK. HOWEVER BOTH MODELS DID JUST THE SAME SEVERAL DAYS
BEFORE OUR RECENT BLIZZARD...SO WE CANNOT HAVE ANY DEGREE OF
CONFIDENCE WITH EITHER A HIT OR A MISS THIS FAR OUT IN TIME. WE
WILL CONTINUE TO USE A MODEL BLEND INCLUDING THEIR ENSEMBLES AS
THERE IS A HIGH DEGREE OF SPREAD AMONGST THEM.

 

This shortwave globally is a small feature but its important to the progression of the upstream low and how much ridging develops ahead of that.

 

The benchmark commented on by NCEP is a low track further west and deeper, we'll see if that's still the case tomorrow morning.

 

Indeed if you look at the forecaster map I linked to earlier NCEP have that shortwave deeper and a little further west than the UKMO.
 

Edited January 28, 2015 by nick sussex

[Tamara]

I suggest that on those op runs that are more mobile, we look for the flow to dive se again days 10/12 as per now, creating another euro trough.

Yes. The rinse and recycle theme leads itself to a further +PNA retrogression across the Pacific hard on the heels of when the pattern (attempts) to flatten out - as spoken about earlier. This leads to subsequent repeated downstream amplification and euro trough. As suggested in the previous post this evening, the holding pattern of the current displaced vortex sustaining the northerly eats up time till both atmospheric and stratospheric forcings support a reload.  snowkings post this evening (the MJO element of the GWO budget) further covers future upstream amplification possibilities very well

[steveinsussex]

I think looking ahead further than the end of the weekend is rather futile at the moment, surely the main interest lays in what may pop up in the short term and the interesting potential on the doorstep.

[weather eater]

I would agree with WIB in regards the fact that at least one run would have to show something more shall we say progressive but it is one operational run and a possible breakdown in 5/6 days is a long way off in synoptic evolution terms. However, there is no getting away from the fact that it has credence if little support yet.

[Banbury]

Fax charts for Sat / Sun have troughs running down the UK, be very surprised if it stayed dry

[Mucka]

Good morning from "rainy" Manchester 

 

GFS 00z shows the 18z was just a progressive run and is more amplified again.

 

 

Of course that means UKMO goes the other way (compared to previous runs)

 

 

Not a terrible chart anyway but it looks too progressive from 96h to 120h to me so I wouldn't read much into it.

 

 

If I'm reading it right the low disrupts against the ridge enough to split some energy South so I really can't see how that low would develop so much and force so much energy NE. I think we will likely see a much better 12z, especially if the ECM is more in line with GFS..

Edited January 29, 2015 by Mucka

[KTtom]

Also worth noting that reasonable agreement that the low for early next week is modeled to the west of the UK, whilst of interest it is actually a bit of a pain as it temporarily cuts off the northerly flow just as its at its most intense.

 

 

GEM is an astonishing run from start to finish....don't suppose its recently had an upgrade and is now the most accurate model ???

 

 

 

Edited January 29, 2015 by KTtom

[Gary R Betreen]

Does anyone know about this low coming out of Atlantic Canada that may follow the jet stream down and  the UK could be in the path. From what Alex Deakin was saying last night that this could give alot of snow for the UK from Saturday?

[Captain Shortwave]

Still big questions on the risk of snow early next week. The ECM again showing a slower solution for the low moving over the Azores ridge

 

The GFS ens this morning showed a fairly large cluster of Scandi high solutions around the 7-10 day range. The ECM may go the same way.

 

The GEM is a complete snowfest this morning, but it has no support whatsoever. Shame.

[West is Best]

18z flicked the op with the milder members:

 

 

But the 0z has reverted to the op back below:

 

 

But it's closer to the mean and there is a fair bit of support for it. In fact those ensembles are a slight improvement.

 

ECM is interesting at T120:

 

 

But there are problems with the uppers at the key time:

 

 

As with the last slider, the angle isn't great, nor the preceding temps. Colder air briefly is pulled in behind but that's after the bulk of the precipitation has passed.

 

All models are now pointing to a breakdown next week. It looks like it's just a question of when rather than if, and whether it's via a toppling high or straight back to the Atlantic. I'm favouring the latter from upstream signals and ensembles, but we'll see.

 

In the short term we should make the most of what we have. There are some marginal issues with the upper air temps leading to rain and sleet at lower levels especially in the south, particularly this weekend when it will actually be a little milder with temps close to average, but for those who see snow fall, and hopefully settle, enjoy it:    

[That ECM]

http://images.meteociel.fr/im/1295/ECH1-72_ysj0.GIF

I still need convincing the breakdown is coming at the end of next week.

[Jason M]

The GEFS are very interesting this morning IMHO. Although there is still a lot of scatter there is an increasing signal for a mid range easterly this morning. The temptation might be to disregard GEM this morning but I wouldnt personally be betting large sums on it being wrong in the final analysis.

[TEITS]

As others have said I am not convinced of a breakdown just yet, neither would I dismiss the GEM (Shock lol).

 

The reason why the GEM is so excellent is because its your classic scenario of low pressure in the Atlantic that undergoes trough disruption with this going SE. This allows pressure to build to our N. Obviously a rank outsider but cannot be dismissed.

 

Overall though I am very happy with the output. The cold spell continues till at least the 5th Feb and may continue thereafter. What pleases me the most is we seem to be in a position where we are pointing towards a cold outlook even if the Atlantic breaks through. What I mean by this is if this mornings ECM is correct it wouldn't take long before we see a repeat of a trough digging SE once again with cold NW,lys returning. The other option is the Atlantic doesn't break through and we see an E/NE,ly. So for me we are in a win win situation.

[bluearmy]

I might suggest that the modelling post day 8 is to be treats with great caution. strange things are afoot over the polar field, especially on the Asian side although the n pacific and Alaska are also ebbing and flowing with amplification.

there was a time when we had such little confidence in the modelling up there that we would just bin the output when big changes were afoot. I wonder if we have moved on since then?

[nick sussex]

I see the GEM delivers a great run, if you track how this develops its very much in relation to its view of the shortwave which I discussed in my last post and its effect on the upstream low and low heights in ne Canada.

 

Today the GFS 00hrs has now developed that shortwave more compared to its flatter 18hrs run so an improvement in its shorter term output, the ECM is still the weakest with that and develops this later.

[Severe Siberian icy blast]

I might suggest that the modelling post day 8 is to be treats with great caution. strange things are afoot over the polar field, especially on the Asian side although the n pacific and Alaska are also ebbing and flowing with amplification.

there was a time when we had such little confidence in the modelling up there that we would just bin the output when big changes were afoot. I wonder if we have moved on since then?

I wish I could post charts but damn useless iPad is crap !

It really amuses me how one or two can promote breakdown every day , when every day we see the cold air extended . When I look at the GEM it's evolution looks more than feeseble . Why ? Because this isn't just something it's picked out a hat . The models have been slowly sniffing around the idea of an easterly post 5th February for a while now . Even at t168 on the big two we can see the high trying to ridge into Scandi . Indeed in fi the gfs creates a major block silencing the Atlantic and lots of trough distruption , sending europe well and truly into the freezer , then a look at the ensembles and we can see there's somethign in the water. Definately onto something .

In the mean time we have a good cold 7 days to look forward to with snow at times for many at some point . Really quite optimistic going into February and certainly wouldn't stick my kneck out and say when not if the Atlantic breaks through . Interesting times