Model output discussion 02/02/20

[nick sussex]

2 minutes ago, weirpig said:

No fear  the Nav gem  is here   in line with other models  with a low of 985  as it passes the south east 

   

Lol ! I expect even the lowly NAVGEM to be more right than the UK4.

The issue isn’t just the track of the low but the precip rates . I think it’s tosh to be honest .

[weirpig]

Whilst myself and others have been watching Thursdays low   The icon on saturday really cranks the winds up a notch   some areas could see very excessive wind gusts  yet again.  Hate to be in Blackpool 

Edited February 25, 2020 by weirpig

[snowray]

1 hour ago, tight isobar said:

That's 1 of an array of plots\possible outs...and if we're nit picking data atm.....it's as we stand South of the Midlands in firing line for any snow!!!!..and the feature looks likely to end as just that....a channel lps

Interesting developments this afternoons from the Met Office, PPN further south than GFS, snow showers further north and a clump of snow around the London area of all places that they are keeping an eye on.

 

Here is euro4's take on things.

 

Edited February 25, 2020 by snowray

[Snowy L]

6 minutes ago, snowray said:

Interesting developments this afternoons from the Met Office, PPN further south than GFS, snow showers further north and a clump of snow around the London area of all places that they are keeping an eye on.

 

Oh yes the famous urban cold Island effect.

[snowray]

1 minute ago, Snowy L said:

Oh yes the famous urban cold Island effect.

Yes mighty strange to see that blob of white just over the London area.

[shaky]

9 minutes ago, snowray said:

Interesting developments this afternoons from the Met Office, PPN further south than GFS, snow showers further north and a clump of snow around the London area of all places that they are keeping an eye on.

 

Here is euro4's take on things.

 

Is that snow across the midlands on the met office chart or just cloud?

[snowray]

1 minute ago, shaky said:

Is that snow across the midlands on the met office chart or just cloud?

Cloud I think, but he did say snow on the northern boundary. I hate them graphics, much preferred the old magnetic symbols that they could just move around.

[weirpig]

4 minutes ago, shaky said:

Is that snow across the midlands on the met office chart or just cloud?

Cloud  i think.  Looks like the precipitation just get to the South Of Brum,  

[shaky]

8 minutes ago, weirpig said:

Cloud  i think.  Looks like the precipitation just get to the South Of Brum,  

Looks like ecm!!!maybe gfs will edge south after all on the 12zs

[stodge]

2 hours ago, IDO said:

I find it hard to be inspired by the next 16-days and Cohen's blog is confident a positive AO remains for that time period so basically more of the same with the odd interlude like this week where the scraps of cold may get some snow to some. Hopefully with the +AO we may see the bulk of the tPV relax in our sector to get a settled spell, but based on the repeating pattern it will not have longevity. No sign of any tropical forcing. Maybe you see it different?

The Cohen blog is quite interesting as he suggests the IOD was not the main reason for the mild winter:

https://www.aer.com/science-research/climate-weather/arctic-oscillation/

 

Cohen does suggest normal to below normal temperatures for the UK over the next couple of weeks.

I'd also suggest while he doesn't see the IOD as a reason for the mild winter, he hasn't got a better (or rather another) reason at this time. 

Finally, the question needs to be asked what happened this winter that the PV became so strong and the AO so positive.  I do believe that the extreme positive AO was in large part related to the strong PV.  But what caused the strong PV?  I know the direct answer to this question.  The large-scale circulation pattern in the NH was hostile to disrupting the PV for all three winter months of December, January and February.  The pattern most favourable for disrupting the PV is ridging/high pressure across Scandinavia and the Urals with troughing/low pressure in East Asia the northern North Pacific.  This pattern existed in November, when we observed the only disruption to the PV this fall and winter, but the opposite pattern has persisted non-stop for three straight months (see Figure iv). 

Weather patterns typically change every week or so what caused the same weather pattern to persist for three months?  I have no idea and I don’t think there are any easy answers. For much of the winter as I have discussed previously, I do believe that Arctic sea anomalies were not favourable for disrupting the PV but I fail to see how that is really the answer.  The Madden Julian Oscillation (MJO) did behave strangely this winter but it did vary and the MJO were in the phases considered most favourable for disrupting the PV (Garfinkel et al. 2012).  People have mentioned the Indian Ocean Dipole (IOD) being in the positive phase but I just checked and the period when the PV was the least susceptible to weakening and the AO was its most positive, the late 1980’s early 1990’s, the IOD was predominantly negative.  So, for now I believe any easy answers will remain elusive.

So the question remains - why, once the pattern changed in December did or has it remained so persistent?

[Ice Day]

The Arome (not the best I know), going for quite a bit of wintry shower activity this afternoon / evening. 

  

The old adage on here of 'now-casting' has rarely been as relevant as over the next few days.  For what it's worth, I think the middle swathe of Wales and England could well do quite nicely out of this upcoming period, maybe some back-edge snow for the South East/East Anglia?  

Finally we have some interest during this most pathetic excuse for a UK winter!!! 

[Mapantz]

The UKV has been very consistent regarding Thursday - not much of a deal. Ties in with the E4 and the FAX charts.

[shaky]

6 minutes ago, Mapantz said:

The UKV has been very consistent regarding Thursday - not much of a deal. Ties in with the E4 and the FAX charts.

Yeh if gfs shows the same as the 00z and 06z though i shall then be taking gfs very seriously!!if and its a big if!!if the the gfs turns out correct it would a huge fail for e4 and ukv as im sure they are the higher resolution models?

[snowray]

5 minutes ago, shaky said:

Yeh if gfs shows the same as the 00z and 06z though i shall then be taking gfs very seriously!!if and its a big if!!if the the gfs turns out correct it would a huge fail for e4 and ukv as im sure they are the higher resolution models?

Surely the 12z runs will start to pin this down, ICON about to roll out, will there be any more surprises this afternoon? 

[Mike Poole]

Yesterday's PEARP ensembles showed not much chance of snow except in the top 10% for the midlands and south. Today's show an improvement but with a proviso, here the 6z cumulative snow at 10%, 50%, 90% of the probability distribution, at T66 so covering Thursday event:

So increased likelihood of seeing some snow for some compared to yesterday, but does look north of the M4 now, that's the proviso, and by no means certain there either.  I think this one will come down to a nowcast, but let's see what the 12z's say!

Edited February 25, 2020 by Mike Poole

[snowrye]

Another non snow event for anyone below the m4 lol

[shaky]

Icon out to 30 hours

[weirpig]

3 minutes ago, shaky said:

Icon out to 30 hours

Further south on this run.  I would have thought  if only slightly 

Edited February 25, 2020 by weirpig

[Mike Poole]

ICON T42:

Difficulty coinciding the precipitation with the cool (I can't say cold) uppers here, if this one is right, could be a non-event.

[weirpig]

A rain to snow event showing for Thursday       roughly same position as the 6z run  for the Arp

 

Edited February 25, 2020 by weirpig

[Mike Poole]

1 minute ago, weirpig said:

A rain to snow event showing for Thursday       roughly same position as the 6z run 

 

For northern France?

[weirpig]

4 minutes ago, Mike Poole said:

For northern France?

No  Surprisingly for us   Thats the Arp   after it turns to snow.   before that its a rain/sleety mix    to compare  here is the icons position 

Edited February 25, 2020 by weirpig

[Radiating Dendrite]

3 minutes ago, weirpig said:

 

 

Just looks a rain event anywhere south of Brum - which is where the precipitation will be.

This looks like a cold rain / sleet fest to me.

[Snowy L]

2 minutes ago, Radiating Dendrite said:

Just looks a rain event anywhere south of Brum - which is where the precipitation will be.

This looks like a cold rain / sleet fest to me.

Moderate snow for North Midlands on that.

[weirpig]

2 minutes ago, Radiating Dendrite said:

Just looks a rain event anywhere south of Brum - which is where the precipitation will be.

This looks like a cold rain / sleet fest to me.

Yep  nothing exciting  i would have thought    sums this winter up