Model Output Discussion. 3/12/2022. How cold will it get?

[josh-weather]

17 minutes ago, Notty said:

It is odd that the model runs are published with impossible/unprecedented situations. I would have imagined that really silly modelling would be highlighted and reviewed by humans. It is a bit like poor payment systems that send ridiculously high payments out to people. Where is the common sense check?

There is a human check - professional forecasters do not just present a run as fact and will certainly not just take them at face value. The fact that us normies can also see them is nice transparency and a service to us all. It's really a great thing that we have access to so much raw output and can try and make our own forecasts from it - and if we do so, that necessarily has to include deciding what is or isn't realistic in the output.

 

Edit: and if someone in NOAA decided not to release a run on the basis of one low, what would the effect be on all the other forecasters internationally looking to use the model? They can't just pull a run on their own judgement. It is a model with international coverage and use.

Edited December 3, 2022 by josh-weather

[Battleground Snow]

I like the look of the control again this evening, looks more realistic.

Hard to take a break from each run at the moment, with these rare December synoptics on offer.

[sheikhy]

By the way another beauty of a control and mean out to 192 hours!!!

[Howie]

5 minutes ago, Eagle Eye said:

Ayy yes, seems to form in the mid Atlantic (ish) from an elongated wave of air from just off the coast West Africa.

The forcing that seemingly pushes it more extreme seems to almost be contaminated.

Look at all of that shearing churning around it, surely scuppering the low's development significantly?

The speed at which it forms is quite incredible in itself, a slightly lifting of forcing from the south and we see an almost immediate reaction.

SST's wise and we're above average in that area but it's still on the borderline for tropical cyclone development and I know we aren't close enough yet but I'm not seeing too much in the way of a loop current where it forms and that would be my only explanation other than significant forcing counteracting the shearing but as we get closer I think the track should start to shift. That shear is going to shift the Low Level Circulation (LLC) away (in my opinion and that's if it forms in the first place) from the Convective Centre (CC) meaning that the Storm essentially, shouldn't be able to increase it's strength and so shouldn't become too much of a problem except maybe helping dump some snow for us with some slight changes to it's track (only a couple hundred miles and it favours us really).  For whatever reason though, the GFS sees it's tail strengthening, perhaps it thinks it's entered a zone of significantly less shear and the LLC and CC push back together and therefore it follows the upper winds.

SST's

Upper-winds

The upper-level winds flow like that, not on their own but due to a divergent wind pattern just above the Amazon Rainforest which pushes up and eventually interacts with that Tropical Atlantic jet.

There's so much that can still go wrong with this potential disturbance that I think we could see a flip by tomorrow or Monday on either it's track, intensity or even it's formation.

Yup that second chart definitely looks like some kind of error in the data there? You don't even see a tropical storm form that quickly at peak hurricane season with 0 wind shear

Edited December 3, 2022 by Howie

[CSC]

What I have noticed in recent times is the GFS is good at picking up anomolies or feature changes, where as the MetOffice is good at picking up the general direction of weather. This is why tonight makes for interesting viewing. The GFS has just forecasted some bonkers looking tropical storm. Is this a new feature, or just a blip? We will find out soon!

[chionomaniac]

The Azores low looks overblown to me, but in any case will have blown itself out before it reaches the UK. The modelling of the energy in jet stream dynamics here is all important. 
 

So let’s get back to basics… a surface low pressure forms at the left exit point of a strong jet stream where temperature differentials are at the maximum. Because of the Greenland high this is occurring far further south than usual as shown below

because of this we have a player in the placement of a battle zone. But this will be a dissipating event should it reach the UK and we need to be concentrating on the background long wave patterns to determine what the future holds post this. And imo these are embedded and will be tough to shift. Scandi high will follow. Mark my words. 

[CSC]

I think overall the temperatures will be quite accurate, but these GFS ensembles don't look right to me. It seems like the one sheep has followed the pack. I wouldn't be surprised to wake up tomorrow with the average maximums being -2 for next weekend amd these numbers entirely shifted. It only takes a minor change for all these numbers to shift!

[blizzard81]

Much talk on here about that mega gfs atlantic storm and even more talk about discounting it as an impossibility. However, it's only 24 hours since THAT ECM which depressed a Friday evening on here (attached to jog memories). It was this same bomb system (all be it a more watered down version) that broke the cold spell on that run. Maybe it shouldn't be discounted totally if it has been shown by the ecm and gfs within the space of 24 hours. 

Edited December 3, 2022 by blizzard81

[CSC]

1 minute ago, blizzard81 said:

Much talk on here about that mega gfs atlantic storm and even more talked about discounting it as an impossibility. However, it's only 24 hours since THAT ECM which depressed a Friday evening on here (attached to jog memories). It was this same bomb system (all be it a more watered down version) that broke the cold spell on that run. Maybe it shouldn't be discounted totally if it has been showed by the ecm and gfs within the space of 24 hours. 

a very good point, one to watch for sure!

[Jason M]

Looking at the GEFS out to 192 and it's a mess tbh. Lots of uncertainty in the forecast. My advice is to ignore the 'mean' charts from this suite because they will be worthless looking through the individual ensembles. More runs needed .

[Liam Burge]

3 minutes ago, blizzard81 said:

Much talk on here about that mega gfs atlantic storm and even more talked about discounting it as an impossibility. However, it's only 24 hours since THAT ECM which depressed a Friday evening on here (attached to jog memories). It was this same bomb system (all be it a more watered down version) that broke the cold spell on that run. Maybe it shouldn't be discounted totally if it has been showed by the ecm and gfs within the space of 24 hours. 

I'm not discounting it, however I do believe that the models are overdoing the strength of this system. Like someone earlier posted that it deepens 20mb in 4 hours, which is just unprecedented deepening even in the most favourable conditions on the planet, and not some Atlantic ocean that is just a bit warmer than average. We just need to monitor this system and see where it tracks in the next outlooks, and I am 100% expecting the low to be weaker on runs going forward.

Edited December 3, 2022 by Liam Burge

[Eagle Eye]

Just watch it get even stronger on the 0Z runs 

In all seriousness, this can be discussed a length but I'm going to say what nobody wants to hear but needs to be heard, more runs needed.

[blizzard81]

2 minutes ago, Liam Burge said:

I'm not discounting it, however I do believe that the models are overdoing the strength of this system. Like someone earlier posted that it deepens 20mb in 4 hours, which is just unprecedented deepening even in the most favourable conditions on the planet, and not some Atlantic ocean that is just a bit warmer than average. We just need to monitor this system and see where it tracks in the next outlooks, and I am 100% expecting the low to be weaker on runs going forward.

I hope you are right. 

[Derecho]

9 minutes ago, blizzard81 said:

Much talk on here about that mega gfs atlantic storm and even more talked about discounting it as an impossibility. However, it's only 24 hours since THAT ECM which depressed a Friday evening on here (attached to jog memories). It was this same bomb system (all be it a more watered down version) that broke the cold spell on that run. Maybe it shouldn't be discounted totally if it has been showed by the ecm and gfs within the space of 24 hours. 

EDIT: Initially read this as December 2012 which produced THAT ECM, long day..

Mods feel free to delete haha.

Edited December 3, 2022 by Quicksilver1989

[Ladyofthestorm]

So synoptics and models ponit towards a lengthy cold and potentially snowy situation. 

 

I can't see that Greenie high relinquishing it's grip before the third week. 

 

 

[Notty]

2 minutes ago, Liam Burge said:

I'm not discounting it, however I do believe that the models are overdoing the strength of this system. Like someone early posted that it deepens 20mb in 4 hours, which is just unprecedented deepening even in the most favourable conditions on the planet, and not some Atlantic ocean that is just a bit warmer than average. We just need to monitor this system and see where it tracks in the next outlooks, and I am 100% expecting the low to be weaker on runs going forward.

The proof of the pudding is in the eating. It’ll be really interesting to see how this pans out !

[Liam Burge]

1 minute ago, blizzard81 said:

I hope you are right. 

If I am wrong, then we are going to be watching something completely unprecedented.

[CSC]

Ok this is playing devills advocate, but.. in the event that this ridiculous tropical storm ended up collding with severe cold in the UK, what kind of preci[ numbers are we thinking? Unprecedented if it verified..

[E17boy]

Just when I had thought it had been a superb evening of model watching and could go sleep without a flicker of worry on this upcoming cold spell. Now we have another thing to deal with this spinning low. Oh well I guess tomorrow shall give us more insight on this. Whether it’s a new developing trend that will change the pattern over us or whether it will be a passing feature and leave us alone who knows. Overall some interesting model watching.

night night all 

[blizzard81]

Just now, Quicksilver1989 said:

You cannot compare the two. That ECM (December 2012) was caused by an easterly that ended up being weaker then forecast so high pressure sank south. We then ended up with a mild southerly.

No tropical storm in sight.

The GFS is suggesting an unusually rapid intensification of a quite far north tropical storm in a high shear environment. Chalk and cheese

By THAT ECM, I was referring to yesterday's 12z run. You need to read my post again. 

[Derecho]

2 minutes ago, blizzard81 said:

By THAT ECM, I was referring to yesterday's 12z run. You need to read my post again. 

Noticed it as soon as I read it. THAT ECM is infamous on this forum....

Worth noting the EC yesterday gave that low an easterly push by interacting with a nearby secondary low, whereas the bombing in recent GFS runs has tropical hallmarks.

Edited December 3, 2022 by Quicksilver1989

[blizzard81]

2 minutes ago, Liam Burge said:

If I am wrong, then we are going to be watching something completely unprecedented.

If you are wrong we will just enter into yet another stormy mid December. 

[Allseasons-Si]

5 minutes ago, Liam Burge said:

If I am wrong, then we are going to be watching something completely unprecedented.

And interesting at the same time

we are going to have to pull out all the stops on this one...

...on the south coast

but seriously i am going to stick my neck out that this system will be further south.

Edited December 3, 2022 by Allseasons-si
typo

[Eagle Eye]

1 minute ago, blizzard81 said:

By THAT ECM, I was referring to yesterday's 12z run. You need to read my post again. 

That does make a bit more sense although I think you probably shouldn't call it THAT ECM as we've already seen THAT ECM before, I think yesterday's should forever on be called;

The GFS is better anyway ECM 

[Notty]