Model output discussion 24/01/21

[swfc]

9 minutes ago, Drifter said:

I just can’t understand the driving force for the low just twonking through west-east with hardly any disruption or deviation. 
 

That's our normal flow across the UK. It's not unusual in winter even with a SSW or any jet deviation. Any blocking to the south will enhance it be it temporary. 

[Tim Bland]

6 minutes ago, frosty ground said:

Not sure I would use the London Ensembles when talking about the Pennines. 

What hope casting can you see Tim?

I’m using the London ensembles to evidence there is no chance of the snow in the south this week. I could equally use the Birmingham ones If there was a chance of a sudden backtrack (as some are suggesting / hope casting ) then you will see at least a few ensembles showing it. When the ensembles are that adamant on the pattern then we can accurately make a forecast ...which is some snow Pennines north,  then a brief easterly next weekend. Anything else is (in my opinion) hope casting

[sheikhy]

Para looks like ukmo at 114 hours!!

[swfc]

Just now, Tim Bland said:

I’m using the London ensembles to evidence there is no chance of the snow in the south this week. I could equally use the Birmingham ones If there was a chance of a sudden backtrack (as some are suggesting / hope casting ) then you will see at least a few ensembles showing it. When the ensembles are that adamant on the pattern then we can accurately make a forecast ...which is some snow Pennines north,  then a brief easterly next weekend. Anything else is (in my opinion) hope casting

The only snow as such this week will be in the north east and Scotland. Cold air hanging on there then transfers South at the weekend 

[Day 10]

10 minutes ago, Allseasons-si said:

The ICON from 61-120 might please a fair few...

low stalling over N England then heads southeast with a northerly/northeasterly to follow.

Edit: peeps don't look past 120 as there will be lots of chopping and changing to come before that.

Yes agree re ICON.

The angle of attack is also better now and further south, indication of fronts starting to struggle north east.

[MJB]

6 minutes ago, swfc said:

That's our normal flow across the UK. It's not unusual in winter even with a SSW or any jet deviation. Any blocking to the south will enhance it be it temporary. 

yes it is but normally the PV is sat in it's normal position 

Edited January 25, 2021 by MJB

[frosty ground]

2 minutes ago, Tim Bland said:

I’m using the London ensembles to evidence there is no chance of the snow in the south this week. I could equally use the Birmingham ones If there was a chance of a sudden backtrack (as some are suggesting / hope casting ) then you will see at least a few ensembles showing it. When the ensembles are that adamant on the pattern then we can accurately make a forecast ...which is some snow Pennines north,  then a brief easterly next weekend. Anything else is (in my opinion) hope casting

Agree with you or you are a hopecaster?

 

[MJB]

5 minutes ago, Tim Bland said:

I’m using the London ensembles to evidence there is no chance of the snow in the south this week. I could equally use the Birmingham ones If there was a chance of a sudden backtrack (as some are suggesting / hope casting ) then you will see at least a few ensembles showing it. When the ensembles are that adamant on the pattern then we can accurately make a forecast ...which is some snow Pennines north,  then a brief easterly next weekend. Anything else is (in my opinion) hope casting

I agree with you Tim , Sheffield northwards is about your lot and a cold push South after, then a blink and you miss it Easterly , that about  covers the next 5 or so days 

Edited January 25, 2021 by MJB

[nick sussex]

The GFS para looks the best at T114 hours . The shortwave west of Iceland is further west and the wedge looks better placed .

[swfc]

1 minute ago, MJB said:

yes it is but normally the PV is that it it's normal position 

You can have a greenland high and still have low pressure moving  west to east without disruption. Granted its not a true zonal flow but won't help the flooding ete

[Severe Siberian icy blast]

19 minutes ago, MJB said:

Blink and you miss it though , the Atlantic is bombing through 

I'm not sure I buy that tbh, the main vortex driving the pattern is northeast, the low song bomb up like that with nothing fueling it, the wedge picked up by the models inside t100 is because they're not picked up until nearer the time hence the models so quick to blow them away 

[frosty ground]

When we see changes like this in the mid term, and the flow west to east being held up in the short term I really don't understand the need to say people are hopecasting by simply highlighting what the actual models are showing and doing. 

 

[Kentspur]

10 minutes ago, swfc said:

That's our normal flow across the UK. It's not unusual in winter even with a SSW or any jet deviation. Any blocking to the south will enhance it be it temporary. 

Also the NE US is set to have atleast a temporary very cold spell later this week and with the winds generally flowing into the Atlantic off of mainland USA this could be partly behind the cyclogenesis& lows deepening out to our west as we know cold air here with a steep thermal gradient difference often blows up the jet stream-never a good thing

Edited January 25, 2021 by Kentspur

[Allseasons-Si]

The gfs is a better run and it would just need a tweak SW and disrupt the low SE at 192 as there is a lot of cold air to our NE with a slither of heights to our north.

 

Edited January 25, 2021 by Allseasons-si
Added text

[Tim Bland]

10 minutes ago, Day 10 said:

Yes agree re ICON.

The angle of attack is also better now and further south, indication of fronts starting to struggle north east.

If you look at the area that is hatched (snow) it is only the high ground of the Pennines. Either side EG Manchester and Leeds is rain. 

[nick sussex]

The GEM shows the importance of not having that bloated shortwave west of Norway which stops some ridging developing to the ne .

[Day 10]

Just now, Tim Bland said:

If you look at the area that is hatched (snow) it is only the high ground of the Pennines. Either side EG Manchester and Leeds is rain. 

I know.

[ALL ABOARD]

You have 4 models that potentially show the cold reasserting itself at day 5,  even if it's only for a brief period saying it won't snow in the south in the next week is ludicrous. 

 

[Battleground Snow]

1 minute ago, nick sussex said:

The GEM shows the importance of not having that bloated shortwave west of Norway which stops some ridging developing to the ne .

Indeed nick by 168 the cold is really trying to push back the Atlantic, similar to the ECM of yesterday evening

[Valleyboy]

25 minutes ago, Drifter said:

I just can’t understand the driving force for the low just twonking through west-east with hardly any disruption or deviation. 
 

Regardless of any background signals, i.e. SSW, one thing that is rarely mentioned but is a constant, it the earths rotation.  This is the main driver.  Now if we could just reverse this, we would be in a great place!

 

27 minutes ago, MJB said:

Low after Low coming our way , just why is this ? I would have expected a quieter time 

 

[nick sussex]

The models agree on the Atlantic low moving east quickly by day 6 .

The uncertainty is the angle of attack and whether we might see more trough disruption and some frontal snow as that happens .

[SLEETY]

Weird how great day 5 looks then 24 hours later all the models look hopeless,and all cold air getting pushed away.Maybe they are all wrong and fl is 4 days away.Lets hope so anyway or its miles away to cold again.

Edited January 25, 2021 by SLEETY

[Severe Siberian icy blast]

3 minutes ago, ALL ABOARD said:

You have 4 models that potentially show the cold reasserting itself at day 5,  even if it's only for a brief period saying it won't snow in the south in the next week is ludicrous. 

 

How many charts even past 120 come off? 

Especially when we have wedges of high pressures popping up that just don't get picked upon at that range. 

Once one goes under, they all will 

[Day 10]

1 minute ago, SLEETY said:

Weird how great day 5 looks then 24 hours all the models look hopeless,and all cold air getting pushed.Maybe they are all wrong and fl is 4 days away.Lets hope so anyway.

Yes exactly, if day 3-5 is a struggle then what's the point in looking much further. I am hoping to see some form of frontal snow develop.

[Battleground Snow]

By 210 on the gem the cold wins out and a Iceland high forms, this is probably the best we can hope for in the midterm, on to the ECM we go.