Model output discussion - here comes the beast!

[John Michael How]

9 minutes ago, Lampostwatcher said:

gfs and ukmo fantastic for the South of the UK ☺

So a Kent clipper/ Thames streamer looking the most favourable on UKMO then? ( suits me and about half of the population that reside in Southern and Eastern areas ?⛷) still I do hope we have more of a blend of the outputs to favour more of the nation

[terrier]

Gfs & ukmo don’t look bad to me. Just a variation on theme at moment. But seems they is gonna be some of this tonight 

[Johnp]

1 minute ago, Staffordshire said:

I could counter that with the question, why would it not? If there is growing support for it to do so, the likelihood of it doing so thus increases.

Don't get me wrong, I would love for it to stay further North, but it shouldn't be ignored that there is growing support for the high to extended towards our Norhtern shores.

By that rationale the high will be over the Sahara by Saturday would it not?

[SMU]

1 minute ago, Staffordshire said:

Of course not, I am saying it because it can be determined that the extent to which the high will blow up has been underestimated thus far, and with growing support for it to end up further south, comes more confidence in it doing so.

How can you can have growing support when 1 model moves south by about 200 miles @144 & one model moves North by severel hundred miles at the same time-

There all within a cone of margin - 

What it actually means is theres no clarity or resolution- 

Just the same as the 12z ECM was The coldest & the 00z was the warmest -

 

 

[Derecho]

4 minutes ago, SLEETY said:

No the cold uppers would be not cut off ,how if the coldest uppers are further South and it moves North how can the uppers be higher

Easy, cold uppers heading to France, if the blocking moves to Greenland we get a northerly instead and the cold pool is stuck on the continent.

Yes there would be a brief period of very cold uppers but only its a risky pattern, any further south and convective activity would be really suppressed due to a more stable atmosphere. 

[Lampostwatcher]

all I know is atm in time 

the gfs and the ukmo 12z 

have very cold air still in place for UK with the coldest air south UK 

and snow for many 

[bobbydog]

can we stop with the North/South divide rubbish? wherever it ends up, its nobody's fault. while you're all bickering, the GFS is chucking out a run which looks good for snow for EVERYONE!

[Staffordshire]

1 minute ago, Steve Murr said:

How can you can have growing support when 1 model moves south by about 200 miles @144 & one model moves North by severel hundred miles at the same time-

There all within a cone of margin - 

What it actually means is theres no clarity or resolution- 

Just the same as the 12z ECM was The coldest & the 00z was the warmest -

 

 

ECM caught onto this yesterday, UKMO today, ICON today.

 

We await the ECM of this evening.

[pages]

6 minutes ago, bluearmy said:

no one should be surprised by these 12z  runs so far 

whilst this evolution is being dissected rather more thoroughly than would usually be the case, these changes in a non zonal environment are not unusual at a 5/7 day range and with the second warming also coming through over the past day or so, a reaction by the nwp shouldn’t be unexpected. 

I cautioned to wait for the Thursday 00z output before calling this 

I’m just as disappointed as any of you with the trend but totally not surprised. Hopefully we can see a swing back over the next couple runs to something better re snowfall. 

yes definitely the 2nd warming is causing massive differences to the output run to run. watch where the vortex goes after 84hr on each model all take in different directions and some send shortwave energy across Svalbard splitting the block while GFS just takes the whole thing from Greenland to Siberia around the outside of the block.

[Mucka]

Rather unlikely looking GFS with the embedded trough developing and then stalling over Scotland.

[Jason74]

1 minute ago, bobbydog said:

can we stop with the North/South divide rubbish? wherever it ends up, its nobody's fault. while you're all bickering, the GFS is chucking out a run which looks good for snow for EVERYONE!

Agree. This north/south thing does no favours. 

[SMU]

PS UKMO 144 uppers has -8c across the North of england 

-10c across from the NE to bristol & -12c from EA to IOW (-13 touching east kent )

Unstable flow & low heights will = snow

so if thats the worst southerly run then its still a great run - With a greenland high building -

[Duane S.]

1 minute ago, Staffordshire said:

I could counter that with the question, why would it not? If there is growing support for it to do so, the likelihood of it doing so thus increases.

Don't get me wrong, I would love for it to stay further North, but it shouldn't be ignored that there is growing support for the high to extended towards our Norhtern shores.

Eh? Yes but specifically why would it continue 'trending' southwards? Unless you explain your reasoning, it just looks and sounds like you are basing it on a rather unscientific 'gut feeling'.

 

[WalsallWeather123]

Colder air much further north due to position of high on GFS 12z vs 6z.

Edited February 21, 2018 by WalsallWeather123

[carinthian]

8 hours ago, carinthian said:

Morning all. Another great set of model runs this morning. Best stick to the short range outputs in this situation as we all know out to 240t charts hardly verify but they do indicate some sort of retrogressive set up.All in all, that's one heck of a cold block where ever the high is positioned. So my chart to highlight  is the UKMO 96 t, now showing a super extended block to the north east with central pressure heading towards 1050mb. The latest fax for Saturday shows the human input from the Exeter team, note the embedded warm front crossing Western France, as Ian McCaskell would say, " That's about as warm as a Polar Bears picknic " . I think this is probably a section of warmer upper air in the flow, but will not affect cold surface flow. Looking at this same chart the real cold air is heading for South eastern Britain behind the front moving SW from the Baltic countries. Most models indicate this very cold air mass into British Isles during Sunday. Thereafter , an increased chance of convective snow, especially in Eastern Britain but by then we may be looking for troughs in the flow to push through , hence keep a eye on the fax chart human inputs. Should get back later today with a report from our forecast team over here that may shed some light on snow chances for next week.

C

Afternoon, as promised reporting back with our Forecasting Portal Service experts latest thinking with specific the United Kingdom regarding depth of cold , timing and snowfall. They talk about the large cold block in place over much of Europe by Wednesday with Britain well locked in its midst based on the model 300mb wind flow pattern over much of the Northern Hemisphere which looks conclusive to a prolonged cold spell. Their own model develops a core mass of very cold upper air now developing over Northern Russia, sub -40c  core at 500mb level ( at around 18500ft asl). They predict this cold pool to move W/SW in the direction of the British Isles with a quicker solution than shown by some of the bigger models. Further into the middle of next week looks like a trough or low formation to develop in the flow ,possibly over Poland or Southern Baltic as they have pressure value falling as low as 1015mb. That's something to keep an eye on in later runs. So light snow could start showing up in Southeast parts later in the weekend but the heavier convection snow more likely in Eastern parts in earlier part of next week with possible chance of more organised snowfall by Wednesday or the first day of the new month. So all in all follows UKMO latest forecast regarding snow prospects but the difference could be timing. Hope this all helps.

C

[frosty ground]

3 minutes ago, Staffordshire said:

ECM caught onto this yesterday, UKMO today, ICON today.

 

We await the ECM of this evening.

The operationals.......Hmmmm

ECM 0z 19th
ECM 0z 20th

ECM 0z 21st

Hmmm are you sure........ ?

[danm]

So, UKMO has a southward correction and the GFS has a northward correction - no agreement here beyond Monday. 

Surely this alone should make people stop and realise that the medium term pattern is still up in the air? 

At the end of the day we still have generally good to excellent output from the 12zs so far with plenty to play for.

Quite frankly, some of the "we've had less snow than you" arguments on here are pathetic. Are we school children?

[Southender]

Wow, just wow. There are some seriously inaccurate posts flying around at the moment. Please, if you do not understand how to read the models correctly either ask a question or read up on things, there is some excellent learning material on here and across the web. This is a place to learn, but at the same time posting wholly inaccurate info just inflames a situation further.

Anyhooooo, lovely GFS run eh?

Edited February 21, 2018 by Southender

[Singularity]

Still capable of prolonging the cold if the LP to the S can get far E enough.

Not only that but potentially making it more intense again for a time.

The huge contrast with UKMO regarding the orientation of the flow and how much the high remains extended out east tells us that, as with yesterday evening, we still don't really know anything beyond 'cold to very cold with snow chances widely' with respect to the likely outcome next week.

[Mucka]

I really would ignore this GFS run. It will be different tonight because the chances of that trough developing in the same way and stalling over Scotland are less than 1% IMO

[bluearmy]

3 minutes ago, Mucka said:

I really would ignore this GFS run. It will be different tonight because the chances of that trough developing in the same way and stalling over Scotland are less than 1% IMO

You could have just stopped there mucka 

the trend is currently not our friend and the gfs standing as a beacon against it gives me with no comfort whatsoever!

Edited February 21, 2018 by bluearmy

[kev238]

Just now, Mucka said:

I really would ignore this GFS run. It will be different tonight because the chances of that trough developing in the same way and stalling over Scotland are less than 1% IMO

I have to agree as well. That trough won't be there in tonight's run and will totally change the charts ( in my opinion)

What is becoming clear is that there are many different options for next week post the initial cold wave on Sunday night / Monday morning 

it doesn't feel as clear cut as a couple of days ago but a Messier picture might lead to more snow but less cold uppers 

[Staffordshire]

10 minutes ago, frosty ground said:

The operationals.......Hmmmm

ECM 0z 19th
ECM 0z 20th

ECM 0z 21st

Hmmm are you sure........ ?

ECM 12z on the 19th and 20th vs the 0z for 28th 01:00... yes I am sure.

 

GFS 12z much nicer though.

Edited February 21, 2018 by Staffordshire

[Paul]

So, that's another couple of people blocked from posting in here, any more takers?

Those wanting to just moan for moanings sake, please head to the moans thread. Those wanting to troll, please do one. Those wanting to discuss the models, please carry on  

[Mucka]

1 minute ago, bluearmy said:

You could have just stopped there mucka 

the trend is currently not our friend and the gfs standing as a beacon against it fills me with no comfort whatsoever!

I'm not thrilled by the UKMO, ICON and this mornings ECM all going for a less exciting evolution but I still think it is a trend that could be reversed, or at least revised back toward something more favourable for the whole country.

Certainly not something we want to see continued and progressed upon tomorrow but @carinthian's report of a quicker progression to cold sounds hopeful as that would likely have the initial ridge and high further North