Again I would comment that the SSW has the potential to impact NWP accuracy. However, to say models are "unaware" of it is wrong in several ways and is misleading for those trying to learn. I hope that is not what the BBC article is telling people. They may as well say the model is not aware of rain, snow, high pressure or low pressure or you or I.

My understanding is that although there is no inherent bias or AI architecture in NWP algorithms, the resolution with height varies model to model (the EC having more layers than the other two top models). Therefore changes filtering down from above may not be modelled very well with respect surface output, and as said parameters are subject to almost hourly adjustment (primarily satellite data), the volatility is adversely affected.

For the resolution reasons I tend to take more note of the extended EC ensemble when we’re interested in 15 plus days in a SSW (ongoing with another warming) event.

This output is predicting a shift of the mean trough east in the next ten days and heights building to our N and NE and the reason why I’m still optimistic of a colder end of January than the GEFS for example is currently projecting. 

---

Had some fun this morning in the snow. Just over 2cm over the higher ground and drifted in places to have a snowball fight with the kids, albeit briefly. My winter perception has changed a little now with this experience.

All eyes down for the next event.

---

Such a shame it goes badly wrong from here. Normally you would bank this

Yes exactly - onje would look at that chart and it's eye candy with a perfect set up with HP over Svalbard and into Greenland a very strong ridge but for some reason it doesn't deliver and I don't know why that low pressure doesn't get forced southwards - is it the low pressure out in Atlantic or the Azores high pushing another low in or both?? It's frustrating! What's the cause here?

 

 

---

 

Given some of the charts, a yellow submarine may be more useful. 

 

Norwegian Flood?

---

 

My understanding is that although there is no inherent bias or AI architecture in NWP algorithms, the resolution with height varies model to model (the EC having more layers than the other two top models). Therefore changes filtering down from above may not be modelled very well with respect surface output, and as said parameters are subject to almost hourly adjustment (primarily satellite data), the volatility is adversely affected.

For the resolution reasons I tend to take more note of the extended EC ensemble when we’re interested in 15 plus days in a SSW (ongoing with another warming) event.

This output is predicting a shift of the mean trough east in the next ten days and heights building to our N and NE and the reason why I’m still optimistic of a colder end of January than the GEFS for example is currently projecting. 

I can agree with that completely. However, my point was that it is wrong for people to say the models are "not aware" of the SSW. They are not aware of anything because it is all simply 1s and 0s resolving complex equations ( see Wiki: Navier-Stokes).

---

FWIW GEFS35 is still favouring colder conditions in Feb. Others may disagree but I think it has been performing well this winter.

---

A few GEFS still giving some hope. but we know it wont happen

---

FWIW GEFS35 is still favouring colder conditions in Feb. Others may disagree but I think it has been performing well this winter.

Yes I was just looking at ENS for next 30 days- no sign of anything mild but it does look unsettled and cool - maybe cold zonality is the way forward? However after the SSW and the 2nd reversal of zonal flow do you still think there is a chance for proper cold Brian - we are now over half way through winter?

---

If only. Still enough to keep the interest going until the 12zs

 

---

https://www.flightradar24.com/airport/lpl 

---

From a rather cursory look it seems that now the GFS has opted for a less favourable (for us) pattern it has become rather more consistent with the overall picture. Detail obviously changes from run to run but not the major shifts we have been seeing.

---

https://www.flightradar24.com/airport/lpl 

Interesting. Here are the raw METARs. Are they having a barbecue? 
https://www.ogimet.com/display_metars2.php?lang=en&lugar=EGGP&tipo=ALL&ord=REV&nil=SI&fmt=html&ano=2021&mes=01&day=15&hora=11&anof=2021&mesf=01&dayf=16&horaf=11&minf=59&send=send

 

---

GFS appears to be firming up on a very mild spell in the south and Midlands with, as predicted a few days ago, temperatures into the low double digits, possibly up to 13-14c in any sunshine. This was initially showing for one day, but is now showing 2-3 days. A growing sign of a significant warm up and no sign of winter.

---

 

Interesting. Here are the raw METARs. Are they having a barbecue? 
https://www.ogimet.com/display_metars2.php?lang=en&lugar=EGGP&tipo=ALL&ord=REV&nil=SI&fmt=html&ano=2021&mes=01&day=15&hora=11&anof=2021&mesf=01&dayf=16&horaf=11&minf=59&send=send

 

 

LOL. That should skew the modelled temperatures for the next day or so when it is fed into the NWP!!!

---

GFS appears to be firming up on a very mild spell in the south and Midlands with, as predicted a few days ago, temperatures into the low double digits, possibly up to 13-14c in any sunshine. This was initially showing for one day, but is now showing 2-3 days. A growing sign of a significant warm up and no sign of winter.

 Too early still to be confident. However, it could get those of us who plumped for a mild winter back on track. It's a bit like being 65 for 5 and and the sixth wicket putting on 150. 

Edit: I think you may say there are signs of the pitch beginning to lose its pace and bounce. 

---

I notice the GFS esp Operational run in particular has always been the milder option in the FI range or from the 24th. Is this a trend setter? who knows?

---

As the last of this mornings snow now melts its time to start looking to the next event.

Here in Folkestone I've witnessed 3 separate altitude brief snow events locally this winter (4th December, 8th January and 16th January).

At FI 120 hours these charts look tantalising.

Greenland High far enough east to prevent prolonged Tm incursions, deep low pressure advecting cold air south across the UK and an arctic high nosing into Svalbard acting as a conveyor to start ushering very cold very deep arctic air SW'wards. Check out historic cold events of the past and you'll notice many charts looking like this a week or two before.

This progressing pattern with secondary lows spiralling on ever southward tracks will bring cold air a good deal further south with time. 

GFS 120

ECM 120

 

UKMO 120

GEM 120

---

As the last of this mornings snow now melts its time to start looking to the next event.

Here in Folkestone I've witnessed 3 separate altitude brief snow events locally this winter (4th December, 8th January and 16th January).

At FI 120 hours these charts look tantalising.

Greenland High far enough east to prevent prolonged Tm incursions, deep low pressure advecting cold air south across the UK and an arctic high nosing into Svalbard acting as a conveyor to start ushering very cold very deep arctic air SW'wards. Check out historic cold events of the past and you'll notice many charts looking like this a week or two before.

This progressing pattern with secondary lows spiralling on ever southward tracks will bring cold air a good deal further south with time. 

GFS 120

ECM 120

 

UKMO 120

GEM 120

Nice pics - your inbox is full Steve so can't reply!?

What time was the pic taken? Snow falling must have been dry then for it to settle on main roads?

 

---

Such a shame it goes badly wrong from here. Normally you would bank this

Given the current uncertainties due to the SSW I think T+144 is near the limits of accuracy. 

Out towards day 10 and both GFS versions want to put a high pressure centre over southern Portugal; ECM and GEM put it over Morocco. That's a difference of 500-600 miles, which whilst very little in global modellling terms is very significant in terms of whether there's room for LP systems to run to our south or not.

---

 

 Too early still to be confident. However, it could get those of us who plumped for a mild winter back on track. It's a bit like being 65 for 5 and and the sixth wicket putting on 150. 

Edit: I think you may say there are signs of the pitch beginning to lose its pace and bounce. 

There's always the option of the odd beamer, Brian....

Or what the Yanks call a curve ball, perhaps?

---