Model output discussion pm 13/01/2016

[Mark Neal.]

Yes Nick I just spotted that too!

[Nick L]

1 minute ago, Mark N said:

Yes Nick I just spotted that too!

It then piles it southwards into much of the Midlands. It's managed to shift that area of precip several hundred miles in one run - what on earth is going on with the models at the moment?!

[Geordiesnow]

19 minutes ago, blizzard81 said:

I have always noticed during the last 10 years plus that in similar situations, the fax's nearly always follow the ukmo raw output. In most cases they are wrong.

Thats what I keep on saying, too me it just seems like a forecasters drawing version of the UKMO op run going from experience. Yes, there may be also factors in it but I don't really think its adds to any uncertainty though. 

Tomorrow's UKMO run will be interesting, I think it will back down but may still show the slowest set up from cold to mild I feel. 

[Cheshire Freeze]

6 minutes ago, Nick L said:

What on earth...the latest Euro 4 has decided to thrown in a widespread snow event for Saturday night into Sunday morning. Decent accumulations for much of the Midlands and NW England. Quite simply pulled that out of nowhere.

How odd. Bet the MetOffice are scratching their heads at that one. 

[Man With Beard]

Errrr... back to 15C on some runs from latest ECM ens...

[Costa Del Fal]

8 minutes ago, Nick L said:

What on earth...the latest Euro 4 has decided to thrown in a widespread snow event for Saturday night into Sunday morning. Decent accumulations for much of the Midlands and NW England. Quite simply pulled that out of nowhere.

Could explain why the met office symbols now go for widespread snow for much of Sunday here now!

Edited January 14, 2016 by Costa Del Fal

[Nick L]

Just now, CreweCold said:

How odd. Bet the MetOffice are scratching their heads at that one. 

They're not the only ones believe me. Only just finished writing a dry and frosty weekend forecast for these areas.

Can't take that too seriously just yet to be honest. Both GFS and EC keep it over western Scotland, and it's completely at odds with the previous run. Still, an area of interest nonetheless! 

[Mark Neal.]

Just now, Costa Del Fal said:

Could be why he met office symbols now go for widespread snow for much of Sunday here now!

Yes Noticed that earlier aswell. Just going to show even the mesoscale models are strugglng. Strange goings on at moment. 

[karlos1983]

1 minute ago, CreweCold said:

How odd. Bet the MetOffice are scratching their heads at that one. 

It'll probably be corrected south into the West Country by tomorrow and by the time the 06z plays out it'll be in the Algarve 

[Bristawl Si]

Actually if you made a short summary of Ian F's tweets/posts of last few days ( basic message is fed from Meto into Ian as a BBC employee) it's one of model chaos/uncertainty, so why the surprise at the continuing uncertainty on each model output run?

[Nick F]

43 minutes ago, The Enforcer said:

That Jet streak hasn't reached the UK by Thursday. The Jet over the UK is still heading NW to SE at that point, so why do GFS/ECM show mild Atlantic air piling through on Monday?

Because the strengthening streak coming out of the U.S. coincides with an upper vortex/trough extending east out of NE Canada -both of which veer the upper flow and eventually the sfc flow  downstream and  allow milder air to spread NE towards the UK. 

However, before this jet streak arrives, the upper flow is weak enough to be deflected by the block this weekend, so we see the energy trying to under to our SW, hence T+120 UKMO-G and similar fax chart from Exeter have that more favorable 'negative tilt' to low pressure and fronts approaching from the Atlantic.

I think it's not a question of if the Atlantic comes back but more when, given the strong jet streak coming out the US ... the GFS ops are probably being a few days to early bringing in mild SWlys, it has a breakdown in the west as early as Mon morning whereas UKMO more like Wednesday, which could be more likely. Upper block and sfc cold don't give in that quickly from experience.

We are seeing corrections south in the jet and sfc lows on the latest GFS op, so wouldn't be surprised to see this trend continue in the morning runs. Think we will be hard pushed to retain cold until next weekend though, but been a funny few weeks of modelling, so can't totally discount.

Edited January 15, 2016 by Nick F

[bryan629]

10 minutes ago, Nick L said:

It then piles it southwards into much of the Midlands. It's managed to shift that area of precip several hundred miles in one run - what on earth is going on with the models at the moment?!

Synop imagery has this feature also for midnight saturday.. only difference here is this moves promptly west to east.. i think these are GFS generated also.

Your model sounds like something is sliding ... but non the less very intriguing 

 

[Nick L]

To be honest, the previous Euro4 run out to +54 (18:00 Sat) had it well into the Irish Sea, so it hasn't been so inconsistent after all. ARRRGGGGHHHHHHHHH!!!! 

[Singularity]

I don't find that sudden change from Euro4 surprising as Sunday is when the WAA driven by Alex starts to interact with the cold air across the UK. I have seen a few GFS det. runs toying with generating precip out of that in some way which has varied in position from Scotland to Wales.

I'm going to watch the MJO plots tomorrow, as if the MJO ends up closer to UKMO's more amplified solution in phase 2, the composite for Jan suggests we should see some attempt to get the jet to track down into Europe rather than through the UK. GEFS of late have barely produced enough of a signal to have much effect and ECM is right on the COD so no real impact at all.

With such a delicate balance of play coming up, I sense that even relatively small changes in the level of influence from the tropics could make or break a colder outcome with respect to mid-late next week.

 

The trough disruption this weekend through Monday does appear to be influenced mostly by the nature of that low development off Newfoundland, but the track of Alex may also sway things a bit should it end up being further east than expected. Or if it ends up shooting north faster that could also upset things, given how important the timing of interactions is.

I do get the impression that the unlucky outcome is not getting sufficient trough disruption, not based on the model guidance of late but just on the pattern that we are looking at this weekend. It seems a lot of different things are conspiring to come together in just the right way to trash things - but of course this is not yet a given. I believe that anyone who isn't in a state of inconclusiveness about the start of next week isn't taking enough into consideration and/or is overlooking the fact that in such a complex, pretty much unprecedented situation (in terms of this combination of events all at once), the usual ranking order of models isn't going to mean as much as usual. In theory higher-resolution should help, but it can also over-complicate matters... having said that I'm inclined to pay more attention to the high-res when it comes to the development of a compact low in an amplified pattern as we are looking at in the far-eastern U.S. this weekend.

There is a chance that this still won't be resolved in 24 hours time... which does cause the mind to hurt a bit I must say!

[The Enforcer]

40 minutes ago, Nick L said:

What on earth...the latest Euro 4 has decided to thrown in a widespread snow event for Saturday night into Sunday morning. Decent accumulations for much of the Midlands and NW England. Quite simply pulled that out of nowhere.

 

37 minutes ago, Mark N said:

Yes Nick I just spotted that too!

Fax chart has that as a warm front - mild sector alert? I have been expecting a frost on Saturday night (a "severe frost" confirmed as recently on News 24 - 12:25am forecast), which would then be at least something to show from this colder period of weather. I shall be EXTREMELY ANNOYED if this development simply results in some rain or cloud cover moving into this area keeping temperatures above freezing yet again.

Also, I had noticed the occluded front heading down the spine of the UK on the Fax chart for Friday 18z:

but Euro 4 making little of it at this stage:

 

Edited January 15, 2016 by The Enforcer

[chicken soup]

29 minutes ago, Nick L said:

It then piles it southwards into much of the Midlands. It's managed to shift that area of precip several hundred miles in one run - what on earth is going on with the models at the moment?!

Surely you would expect a hi-res model such as this to be correct its only 48 hours off

[Nick L]

1 minute ago, chicken soup said:

Surely you would expect a hi-res model such as this to be correct its only 48 hours off

I find the Euro 4 to be very hit and miss on occasion. At that range I'd rather use the EC, which keeps it firmly over Scotland. While the Euro4 makes it a much more defined trough.

With regards to mild sectors, Euro4 does indeed have one, but uppers remain at -5c or below for much of the Midlands and N England with DPs around zero. On the latest run it would only really be Wales and the far west Mids worrying about marginality.

[The Enforcer]

29 minutes ago, Nick L said:

I find the Euro 4 to be very hit and miss on occasion. At that range I'd rather use the EC, which keeps it firmly over Scotland. While the Euro4 makes it a much more defined trough.

With regards to mild sectors, Euro4 does indeed have one, but uppers remain at -5c or below for much of the Midlands and N England with DPs around zero. On the latest run it would only really be Wales and the far west Mids worrying about marginality.

What does the NMM say - I haven't got all the links to its various outputs at the moment? EDIT - NMM 18z says 'No' on Friday evening and keeps Saturday night to a Scottish affair: http://www.meteociel.fr/modeles/wrfnmm.php?map=20

Does it even get as far south as Oxfordshire on the Euro 4? In my experience every time there is a frontal assault from the north-west incorporating a mild sector, this location is always on the 'rain' side of a diagonal line stretching from North Wales to the South-East.

 

Edited January 15, 2016 by The Enforcer
Found NMM link

[Nick F]

38 minutes ago, Nick L said:

They're not the only ones believe me. Only just finished writing a dry and frosty weekend forecast for these areas.

Can't take that too seriously just yet to be honest. Both GFS and EC keep it over western Scotland, and it's completely at odds with the previous run. Still, an area of interest nonetheless! 

The warm fronts bringing the area of rain, sleet and snow across to the NW and in across Scotland late Saturday appear to be tied in with band of moisture pushing out ahead of Alex, as seen in PWAT charts, given the volatility of Alex once it merges with the deepening low coming out NE Canada, I suspect it's worth keeping on eye on adjustments in that area of precip.

[Timmytour]

 I seem to recall seeing a couple of model runs from the Stella charts of last week where the pressure over Greenland was touching 1080mb

I presume that would have been a record had it come to be?

what would be the record low?  Is GFS 18z in the far reach of FI getting anywhere near it?

Edited January 15, 2016 by Timmytour
typo

[Cheshire Freeze]

Ruddy nora are we about to see a GFS Volte Face?

UKMO day 6 shows a N sea block of sorts

This truly is a fascinating (if infuriating) period of model watching. Never seen anything quite like it.

The question is how far will that Atlantic troughing be pegged back come t+ 0?

Edited January 15, 2016 by CreweCold

[Mucka]

Operationals still can't manage two runs the same even over the usually reliable time-frames but we are seeing them head toward greater trough disruption and cut off high pressure around Iceland though we just need the trough to disrupt a little further South

 

UKMO is of most interest to me out to the mid term because it shows something new again - a diving low

If that comes off then it opens a whole host of new possibilities.

I think below is a good example of how all the models have struggled. It shows UKMO 00z  comparison for what it was predicting for 19th on 00z run yesterday and 00z run today and then below that the same with GFS.

You can see that today's UKMO is more  like yesterday's GFS than its own output while conversely today's GFS is more like yesterday's UKMO than its own output.

To illustrate that I have blended the output below GFS/UKMO then UKMO/GFS but if you didn't know better you would say the adjacent charts were from the same model with just natural run to run variation.

 

If that doesn't prove the folly of having allegiance to one model over another I don't know what does. Yes they each have their own bias but that doesn't make one output right and another wrong - it just means we should take account of it when considering where the reality might lie when we have conflicting output. More opften than not the blend will be your friend.

[chicken soup]

Anyone know what time the euro4 updates please....was looking good on its 18hrs run for sat sun.

[Cheshire Freeze]

Just now, chicken soup said:

Anyone know what time the euro4 updates please....was looking good on its 18hrs run for sat sun.

Another hour

[chicken soup]

Cheers crew