Model output discussion pm 13/01/2016

[john mac]

2 minutes ago, blizzard81 said:

From my limited knowledge, isn't this tropical storm only going to increase the energy in the atlantic, adding energy to the jet stream? As a result, I can only think this storm is more likely to scupper the chances of a prolonged cold spell, not enhance one.

It all depends on the track of the storm. It is predicted to head up into the arctic by some models which would give plenty of waa up into Greenland which would help aid the cold weather staying in situ. As for anything else it's all up in the air still!!!

[Nick F]

33 minutes ago, blizzard81 said:

Anyone know what has caused this tropical storm in the first place? Also, how rare is it for this time of year?

The main reason appears to be above average instability in the Azores area, Levi Cowan (Tropicaltidbits) is a bit of an  expert in tropical meteorology an suggests thus:

https://twitter.com/TropicalTidbits

I think the track of #Alex is fairly well modelled, basically it gets steered by a shortwave upper trough rotating around the large upper low over NW Atlantic, so it goes N then NW and merges with a deepening low that comes out of NE Canada. But the formation of this hurricane has taken models by surprise.

It remains to be seen how this will affect the formation of the ridge north over the UK this weekend and also the direction the upper flow energy will take early next week. The Atlantic jet is fairly weak and wavy next few days and into early next week and ECM still has the jet diving SE on Monday, But a strong jet streak is indicated to drive out of the U.S. early next week and this seems to be what is driving GFS and ECM in progressive Atlantic mobility mode. 

EC JET T+132

GFS JET T+132

So, it's the invigorating jet roaring out of the U.S. next week, both agreed on by GFS and EC, that looks to finally put pay to our cold spell, but some uncertainty how quickly this transition will be. Not helped by the models getting jumpy with #Alex.

 

Edited January 14, 2016 by Nick F

[Djdazzle]

5 minutes ago, blizzard81 said:

From my limited knowledge, isn't this tropical storm only going to increase the energy in the atlantic, adding energy to the jet stream? As a result, I can only think this storm is more likely to scupper the chances of a prolonged cold spell, not enhance one.

I see your logic, but it's probably nowhere near as simple as that. The push of tropical air could cause WAA which may promote blocking. Doubt anyone has a clue at the moment. Wonder what MOGREPS is showing?

[Theresnoway]

26 minutes ago, Timmytour said:

If anyone needs to know why a hurricane forming in January would leave such a question mark hanging over the validity of the various models' output, it may well be worth having a look at the path the 1938 hurricane took ....

The best guide to what happens after such a phenomenon, may be to look back to what the weather did in January 1938. You can see from the below link that after the anticyclone on the 5th, travelled up the west coast of Irleland, a wet and windy month followed. May be the models that are showing a quicker return the Atlantic domination are onto something?

http://www.metoffice.gov.uk/media/pdf/2/j/Jan1938.pdf

Edit: Add link!

Edited January 14, 2016 by Theresnoway

[Timmytour]

Not sure a comparison with 1938 has any merit.....different strength, different path.....etc     but here's how things progressed chart wise anyway.....the month was unextraordinary and pretty mild after the hurricane had passed through... The hurricane formed on the 3rd Jan 1938... these charts shows from that date to the 7th

[radiohead]

Aren't the models quite consistent with showing Alex turning extratropical and then phasing with a low in the north Atlantic well to our west?

[blizzard81]

9 minutes ago, Nick F said:

The main reason appears to be above average instability in the Azores area, Levi Cowan (Tropicaltidbits) is a bit of an  expert in tropical meteorology an suggests thus:

https://twitter.com/TropicalTidbits

I think the track of #Alex is fairly well modelled, basically it gets steered by a shortwave upper trough rotating around the large upper low over NW Atlantic, so it goes N then NW and merges with a deepening low that comes out of NE Canada. But the formation of this hurricane has taken models by surprise.

It remains to be seen how this will affect the formation of the ridge north over the UK this weekend and also the direction the upper flow energy will take early next week. The Atlantic jet is fairly weak and wavy next few days and into early next week and ECM still has the jet diving SE on Monday, But a strong jet streak is indicated to drive out of the U.S. early next week and this seems to be what is driving GFS and ECM in progressive Atlantic mobility mode. 

EC JET T+132

GFS JET T+132

So, it's the invigorating jet roaring out of the U.S. next week, both agreed on by GFS and EC, that looks to finally put pay to our cold spell, but some uncertainty how quickly this transition will be. Not helped by the models getting jumpy with #Alex.

 

Is storm alex causing or adding in any way to that massive jet streak off the US?

[shotski]

23 minutes ago, Djdazzle said:

I see your logic, but it's probably nowhere near as simple as that. The push of tropical air could cause WAA which may promote blocking. Doubt anyone has a clue at the moment. Wonder what MOGREPS is showing?

Glosea 5 is showing a block just south of Greenland 

Edited January 14, 2016 by shotski

[Radiating Dendrite]

The problem comparing back to 1938 is the fact that it formed in a different location and under a completely different set of atmospheric conditions. 

[Djdazzle]

Just now, shotski said:

Mogreps is showing a block just south of Greenland 

Thanks. Which merely adds to the general uncertainty I suppose.

[Timmytour]

1 minute ago, Radiating Dendrite said:

The problem comparing back to 1938 is the fact that it formed in a different location and under a completely different set of atmospheric conditions.

We could derive some hope that it's a "gamechanger".  The November and December preceding the 1938 hurricane were both pretty anticyclonic with the first half of December being very cold in particular.  January and Feb went on to be meh.  Hopefully we'll get the reverse this time

[Trom]

15 minutes ago, Chris1986 said:

Well as it's only ever happend once before in Jan so what can the models compare it against haha. I might have a look at some historical data from that winter. Either way it's going to be interesting. 

Thats exactly at the core of the issues the models face.

As we know the numerical models essentially apply algorithms based on fluid and thermal dynamics to initial variables to attempt to predict a future state.  We also know that the robustness of the algorithms is tested by using historic data (analogues) to predict the past (a process known as backtesting or in the weather world as hind casting).  So in other words can the model predict the past - this is essentially the process used to build and refine the model.

Given in this current period we are dealing with an El nino event with warm waters in both indian and pacific oceans which is a very rare event (I think I read another poster saying the last occurrence was 1963) and a January hurricane in the North Atlantic (last experienced in 1938), it gives you some insight regarding why all the models are struggling and throwing out large changes run to run.  Essentially the algorithms are not really calibrated to cope.

[tight isobar]

Just now, shotski said:

Look a couple of pages back. 

Crewe Cold. 

Glosea "5"..

Not thr Moggy

[blizzard81]

1 minute ago, mulzy said:

Source?

And also what period is this block supposed to take place? Next week?

[Guest]

7 minutes ago, Radiating Dendrite said:

The problem comparing back to 1938 is the fact that it formed in a different location and under a completely different set of atmospheric conditions. 

Other than that, peas in a pod! 

[blizzard81]

Ecm control looks identical to the op and 10 day ensembles go generally very mild. Ecm says alex scuppers uk cold. Thanks alex! Never did like that name!

[blizzard81]

3 minutes ago, shotski said:

Look a couple of pages back. 

Crewe Cold. 

That's glossea seasonal model, not mogreps.

[Nick F]

15 minutes ago, blizzard81 said:

Is storm alex causing or adding in any way to that massive jet streak off the US?

Not really, because Alex loses identity/merges with a deepening normal depression in 48 hrs, well before that strong jet streak emerges from the U.S.

Looking at the 12z EPS postage stamps, majority in agreement for an Atlantic break through from Tuesday / t+120

Before then, on Monday, enough negative tilt in the trough/front moving in from the west to hold back mixing in of milder air to bring a spell of snow across many parts, (as per ECM charts on weatherbell) before turning to rain, these are the precip charts:

Edited January 14, 2016 by Nick F

[Froze were the Days]

33 minutes ago, ajpoolshark said:

help or hindrance?......basically no-one or no supercomputer can unravel this mystery, not even scooby-doo

Post of the day!...adds even more turmoil to the models, as if it wasn't bad enough already. One day we'll get a smooth route to real cold!

[grca]

4 minutes ago, blizzard81 said:

Ecm control looks identical to the op and 10 day ensembles go generally very mild. Ecm says alex scuppers uk cold. Thanks alex! Never did like that name!

I would slightly differ with your view there and suggest that the main group remains cold, and there is an even colder group visible too. Remember this is for the Netherlands therefore locally in the UK it could be different depending on location. The op and the control you could say are at the top end of the potential solutions available.

 

[Ali1977]

Think people are getting carried away here, no model is showing anything but a breakdown " at some point" next week. As far as I can see.

[blizzard81]

Just now, grca said:

I would slightly differ with your view there and suggest that the main group remains cold, and there is an even colder group visible too. Remember this is for the Netherlands therefore locally in the UK it could be different depending on location. The op and the control you could say are at the top end of the potential solutions available.

 

The op and control are run at a higher resolution compared to the ensembles. I disagree with your assessment of the ensembles. You can see with the ensemble mean that they trend much milder.

[SMU]

If anyone fancies doing this

 

also it would be interesting to see the locational plot of the hurricane & the pressure at 500mb at 12z v the locale & initialised conditions on all the models -
Whatevers closest may reveal the early favourite.....
S

[Bristawl Si]

So, is it now all eyes towards End Jan/early Feb for 'delivery' a la GP's &T's predictions?

[ANYWEATHER]

Evening all ! First of all Im  going to say Im loving the seasonal weather, bitingly cold but feels how January should feel! Some folks will get a covering of snow overnight and into tomorrow. High pressure builds briefly later tomorrow. Models show a quick return to the Atlantic during late Sunday into Monday. I really don't think that we will get a snow to rain event late Sunday into Monday as the milder air comes in before.....I would happy to be proved wrong! As for Alex ,I think the models are handling this situation well, although unusual , Models struggle with multiple tropical storms  and hurricanes during the summer.........., this is only one!