Model output discussion - cold proper on the way?

[Midlander]

(This is regarding model output). I don't think the UKMO is promising when you look at the weather forecast map on the MO website, all throughout the 5 day forecast the wind direction is westerly/north westerly, no sign of easterly. I think the UKMO has already switched to the ECMWF.

[Dominic Carey]

I just tweeted the ECM and told it to have a think about it’s behavior 

[kold weather]

2 minutes ago, ICE COLD said:

Oh I know that kold, we definitely have more bites of the cherry it’s just extremely frustrating when we had the first attempt so close (possibley could still happen if UKMO trumps the rest) but it means waiting longer for another chance to get that cold spell .

Think positive, we are so close, but that means Europe gets real cold, ready for all those low pressure systems nearby to help drag in cold surface air for lots of snow.

Hopefully!

[bluearmy]

16 minutes ago, BLAST FROM THE PAST said:

Scandi HP was always transient effect for U.K.  initially for me......although I did expect a more vigorous trough over us next week but that is shallowing on current runs.  Within t72 then I’ll review that affair

 

BFTP 

The form horse currently looking like it wins on both scores....wish washy scandi heights and short lived Euro trough   ........but not beyond salvation just yet .......

[Summer Sun]

GFS P taking a similar route to ECM at t144

[bluearmy]

The gefs mean a downgrade .... still enough members to hang something on though 

[Ricky c]

Ive always been told takes couple bites to get the beast in, not worried. Will be watching close to people that talk sense, and enjoy the model rollercoaster

[Frosty.]

8 minutes ago, bluearmy said:

The gefs mean a downgrade .... still enough members to hang something on though 

It's still a cold 6z mean, very cold at times, especially further north and there is a snow risk..still a million times better than the utter dross we had in the first half of winter!

Edited January 19, 2019 by Frosty.

[kold weather]

8 minutes ago, bluearmy said:

The gefs mean a downgrade .... still enough members to hang something on though 

Yeah not that surprising though given its been trending that way. Still probably 30-40% which are close enough to be worth a watch though.

[Snow Queen one]

To my un trained eye is on the SE tip of the UK might just still be in with a shot of cold.  We still may have a few surprises to come.  At least the models are not showing mild in the next 7 days that's a good thing.

[offerman]

Good morning All

Quite staggering really how the charts yesterday showing snowmegedan to today's charts so different.  

Does anyone know why the GFS charts vary so much from day to day.  Also can someone explain how the charts form where LP HP on what basis. 

It also seems to me that a major strong factor which I mentioned recently that really seems so stubourn on these charts is the HP Azores high which always seems to close to us and also the wrong orientation . We need or to do one of three things.

1. Move very far back westward to allow cold inversion from north or East. 

2. Change its orientation , so if it is going to be so stubourn then at least move in a vertical position as to horizontal. 

3. The HP itself to migrate northward mid Atlantic and further North then tilt to its Northeast. 

The GFS appeared to show all three recently but now seems to have reverted back.

 

does anyone know why it changes so much on a daily basis. 

 

Thank you if you can help explain

 

[joggs]

Agree with the downgrades and a bit of a suprise but got to go with what we have i guess.

Positives are the euro trough and background signals. Also JH great post.

If we think along the lines of, forget the easterly and still snow chances for some.

How many times has a good cold spell taken a few bites of the cherry to evolve.

I fear the ukmo 12z will backtrack but great longer term signals(again)on the rest of the suite. I'm sure us coldies will be rewarded.

Hang in there

[mushymanrob]

for the current ECM/GFS charts to be right, then these charts would need to be spectacularly wrong.  not impossible, but rather unlikely, its a game of odds and ill back these as being most likely .

 

[Dominic Carey]

I’m not sure what those charts are showing?

[feb1991blizzard]

18 minutes ago, bluearmy said:

The gefs mean a downgrade .... still enough members to hang something on though 

We've been here many times, and i think we know the outcome by now once these downgrades start.

[Jason H]

Just now, feb1991blizzard said:

We've been here many times, and i think we know the outcome by now once these downgrades start.

Do you? Could you enlighten me please?

[bluearmy]

6 minutes ago, mushymanrob said:

for the current ECM/GFS charts to be right, then these charts would need to be spectacularly wrong.  not impossible, but rather unlikely, its a game of odds and ill back these as being most likely .

 

They were based on output which is over 24 hours old rob

the 8/14 dayer still looks reasonable - it’s the 6/10 which is out 

[feb1991blizzard]

Euro troughing shallowing out in the extended now as well compared to a day or so ago, less frigid runs at the end of the GEFS as a result.

[Firefly2005]

7 minutes ago, mushymanrob said:

for the current ECM/GFS charts to be right, then these charts would need to be spectacularly wrong.  not impossible, but rather unlikely, its a game of odds and ill back these as being most likely .

 

Could you explain this more to those of us who are lay people and only have a very basic understanding? Thanks in advance

[Derecho]

Well another day and another change... I call them the swingometers for a reason

The 06z swingometers show a complete flip for January 25th and it now actually may become a mild day after all those runs showing an easterly yesterday. A very small number now show a very cold, snowy pattern that was in abundance yesterday. The problem lies with how the low dives across the UK and sets up shop over Italy. The low is nowhere near as deep this morning and therefore little cold is advected eastwards to Europe. The other key is the Azores high which needs to hold back or move across to Scandi quickly.

P10 gives us a straw to clutch but mild / anticyclonic has switched to being the form horse this morning.

 

For the end of the month still plenty of cold runs in there but it feels like chasing rainbows at this stage doesn't it? The control has a second go at a similar cold spell to that being modelled yesterday later on.

 

The global temperature anomaly plot is a picture in itself. The only area of above average temperatures in Europe is....

Edited January 19, 2019 by Quicksilver1989

[damianslaw]

Perhaps not a surprise to see the models trending away from the deep rooted easterly, scandi high scenario - the Ensembles for a long time now have shown mean heights to our NW, not NE, with a deep trough to the east and south east. The trend to deep cold therefore will come courtesy of arctic high joining hands with the azores high and settling over Greenland - GFS 6Z output today very much shows this evolution. The ridging and strong influence of the azores high is expected then, yes it scuppers an easterly onslaught but at the same type is a key ingredient towards the Greenland high scenario as we approach the very end of the month.

In the medium term, a flow from between west and north most likely, which will be cold and snowy for the north, with the jet elongated on a NW-SE path.

Some further short-term pain for long term sustained cold gain...

For the north - the models are showing a very snowy picture, ski resorts will be very happy.

[feb1991blizzard]

2 minutes ago, Jason H said:

Do you? Could you enlighten me please?

Yes, once a good few GEFS in the mid range start to trend up, it never goes back the other way again, rarely within 200 and never within 144.

[FetchCB]

6 minutes ago, offerman said:

Thank you if you can help explain

 

The simplest explanation is chaos theory 

https://en.m.wikipedia.org/wiki/Butterfly_effect

I may be corrected here but atm it seems the models are more sensitive to the initial inputs than is normal 

Although the other thought could be that they are no more chaotic than usual is just the output has more of a focus and the desired outcomes more fragile. By that I mean people don't seem to react when the models flip from a North westerly to a southerly as much as they do from an Easterly to a southerly as the desire is for cold and snow 

 

 

 

[Jason H]

Just now, feb1991blizzard said:

Yes, once a good few GEFS in the mid range start to trend up, it never goes back the other way again, rarely within 200 and never within 144.

So, you're basing this on historical ensemble behaviours? OK. Nothing scientific? I think I'll wait for this evening runs before I comment. No denying that the models in the 7+ day range have trended away from the very cold based on the latest runs though.

[Jackski4]

Not quite sure what to do with myself as I wait for the next UKMO run... Nervous times ahead