Model Output Discussion - Spring Has Sprung

[Daniel*]

11 minutes ago, Eskimo said:

That's based on its own algorithm though so the ECM could still be entirely wrong. The GFS isn't on its own.

A low res algorithm? Expect an embarrassing comedown within next 24 hours IMO.

[feb1991blizzard]

 Daniel*

Normally i would agree but the ens are trending the wrong way too.

[Drifter]

 Daniel* You really are nailing your colours to the mast on this one. I hope you’re right!

[NewEra21]

Those Iberian heights just won’t drop for long enough this winter to allow any real chance of prolonged cold.

Pretty sure once Spring arrives, those heights will be nowhere to be seen. As always!

[Penrith Snow]

TBH I am not expecting much from  this coming cold spell, its nighly unusual for a mild, cyclonic December and January to be followed by a cold, wintry February.

2005 was an exception and even that was muted.

MRF models and indeed the MetO have been predicting cold weather in 10 days time since the New Year and it never seems to arrive in any meaningful way, I can't see mid February being any different.

Andy

 

[Rain All Night]

13 hours ago, RainAllNight said:

Two hours later than I would have liked to have posted this, owing to the ECM ensemble taking much longer than usual to load in full on Meteociel...

12z deterministic runs, Mon 5th to Sun 11th (day 7)

We still have the torment of just one or two models teasing with the possibility of a more ideal shape to the "big low" when it first arrives on our shores later this week. Beyond that, we have the interest of whether any meaningful troughing will form downstream over Europe, and what will happen to the high pressure that is being pushed along towards us by the next Atlantic low.

12z ensemble means, Mon 5th to Mon 19th (day 15)

ECM has a noticeably different flavour to the other two models this afternoon, with the low heights associated with the "big low" taking longer to clear the UK and be replaced by high pressure, and then showing lower mean heights to our south and west later on; nonetheless, the Atlantic is still blocked at the end of the run. ECM also has a better and more prolonged mean easterly for Scotland during the passage of the "big low" itself.

0z deterministic runs, Mon 5th to Mon 12th (day 7)

Hats off to the UKMO and the GFS for their persistence with their respective diametrically opposed solutions, and well done to the ECM for producing a believable middle ground instead of blowing up the low. The situation after the "big low" departs looks like a real mess that's going to take a few more days of runs to clarify.

0z ensemble member 850hPa temps (for Dorset), Mon 5th to Tue 13th (day 8 )

Fairly unanimous agreement that modest cold is coming to the south coast from about the 10th onwards. Note those fabulous wind roses on the ECM meteogram, in conjunction with my comments on the ECM ensemble mean below.

ECM

GFS, UKMO, ECM meteogram (black line shows day 8; note the wind roses)

0z ensemble means, Mon 5th to Tue 20th (day 15)

The ECM ensemble mean is great whether it's dry or cold that you want, with a mean anticyclone showing over the UK and/or Scandinavia for a significant part of the run. The GFS mean isn't as good for cold, with heights stronger over and to the south of the UK but weaker elsewhere. The GEM ensemble lets the mean Atlantic depression reach the southern UK twice, once as soon as our "big low" has departed, and then again right at the end of the run, but builds a similar mean anticyclone to the ECM in between. ECM and GEM both have some mean heights up in the south Greenland/Iceland area at the end of their runs.

 

Edited February 5 by RainAllNight

[CoventryWeather]

The GFS has virtually no support across any other models. Others have slowly started to head towards the ECM and UKMO, which will be the solution closest to reality. 

Short range modelling also siding more towards UKMO, some even further south than that. 

[nick sussex]

 feb1991blizzard

Yes the 06 hrs are awful. This really all stems from the blown up low tracking north . Compared to yesterday they are a massive downgrade .

[Benny123]

Beeb brings that snow-line a little further South this morning.. stresses uncertainty though. I imagine it'll be more transient than that. 

[AO-]

 nick sussex

It is not just awful, but also rather unlikely, I suppose. The outcome doesn't make sense to me and is caused by the bias towards deepening of shortwaves/throughs too much. The solution of EC makes more sense, but still the answer could be somewhere inbetween both GFS and EC. We cannot write it off instantly. What the EPS of GFS is concerned, I have seen it Swapping a lot the past few weeks. 

[AO-]

For London it is by definition an outlier, but only from the 13th onwards. This implies for me that this 06h is a rather unlikely solution. 

Edited February 5 by AO-

[bluearmy]

Whilst the macro pattern post the transition remains the same, the ridging looks too far east to allow for the wintry conditions most on here are looking for. Currently a Low Countries system deepening and drifting a little west is the most likely option to deliver next week.  But that’s currently a straw rather than a likely solution. 

we are seeing continued west Atlantic troughing on the modelling - that won’t allow a standard mid Atlantic ridge to establish (of the type many envisaged).  If things fall well then we could see an active southerly jet far enough south to make the south of the U.K. a battle zone.  For now, that looks 50/50 on those runs which develop that theme with that zone further north as the option. 

A quick downwelling wave from a possible split ssw would add more uncertainty re where the pieces of the puzzle end up for the last third of feb. 

at least we are in the raffle and have plenty to watch - been like that for much of this winter though.  

[Mcconnor8]

UKMO 06z run that goes to 66 Hours did shift the snow boundary North compared to the 0z run.

[AO-]

The best possible outcome in the 06EPS is p13. An easterly setting up at day 8.

[Chesil View]

Gfs 06z is even more laughable than the 0z.  No other models suggest this outcome in fact they've trendedmore towards the ukmo/ecm solutions in both the short and medium term.

That's the tbing with the Gfs though, when it goes nuts. It goes really nuts be that mild or cold solutions.

Anyone remember just before the the January channel low when it had a huge Griceland block and low after low dropping southwest across us out of Scandi.

[damianslaw]

I said yesterday the key factor is the depth and extent of cold air set to advect south through the UK on Wednesday. As we know cold air is denser and will hold forcing on the incoming low.. in these set ups it is very complex where the frontal activity will align. It won't be until Wednesday the models I feel will align, and they may still be wrong with the outcome. A coming together between GFS vs UKMO/ECM i.e. something inbetween may well be where we end up... but lots of time to go yet before we will know for certain. Sense today will be an exhausting one for anyone watching each model run churn out and trying to decipher eventual outcome. 

Edited February 5 by damianslaw

[Bricriu]

If the GFS doesn't backtrack  by this evening  I think we are going to end up in a half-way house solution which means cold rain for most on lower ground . As regards  later on this month, what if we see a repeat  of what happened in January  with a ssw scuppering a cold spell.  Although knowing our luck a proper freeze will finally take hold in March.  

Edited February 5 by Bricriu

[BarnetBlizzard]

11 minutes ago, bluearmy said:

at least we are in the raffle and have plenty to watch - been like that for much of this winter though.  

I think this sums it up well - not sure I've seen a winter with so many good day 13-15 charts. It feels like we've been in with a chance multiple times but the pieces have not quite fallen in place.

As you said though, we've still got a couple of tickets remaining - lets see if we can win the raffle right at the end. 

[phil nw.]

 CoventryWeather

Comparing the T84 fax  with gfs 06z we can see the fronts are further north on the gfs by Thursday 12z

 

The gfs has run 6hrs later of course but given this morning's met office warnings which fit the fax you would tend to favour their view  based on their short range data.Having said that there is still room for a small change even now as we are looking at a wriggling set of fronts extending from a complex developing area of low pressure out in the Atlantic.

[mountain shadow]

 Benny123

Now showing the snow band further North.

 

[Eagle Eye]

AAM tendency definitely down over next few days but the actual total momentum ignoring the tendency is still +VE easily compared to recent and long term averages, any +VE EAMT event soon would lead to probably the largest AAM response of the Winter.

[winterof79]

 LukesluckybunchThankfully the MET have much more at their disposal.

Wonder what NAO discussions think of GFS #Nick sussex

 LukesluckybunchThankfully the MET have much more at their disposal.

Wonder what NAO discussions think of GFS #Nick sussex

[MattStoke]

 mountain shadow Matches the ECM. Funny that.

[nick sussex]

 winterof79

Upstream NCEP are quite happy with the GFS .

The issues around the UK with the low aren’t greatly effected by the upstream pattern at that stage .

Its not just the track of the low which is the issue but whether it splits into a complex system . This makes a big difference . Nick F talks about this on page 95 .

Edited February 5 by nick sussex

[johncam]

So looks EC46 poor again,  no high to our NW just looks our now normal default winter weather. Nothing to get excited about.