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Model output discussion 02/02/20


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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.

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A pretty lively weekend to come for the UK. Storm Dennis will impact the UK at the weekend, although it won't be as powerful as Storm Ciara. It is being powered once again by a very powerful jet strea

Im 'personally ' logging of now until October \November...and I honestly pray\hope that when I return...things will be a little better at least for our overall situation.!!! I wish you all happiness..

Sorry. But i think its time to stop all this now. None of us know what weather the virus prefers. Its new. I come on here to escape the 'expert opinion " on Covid 19, please  can we just continue with

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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     

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1 hour ago, stodge said:

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?

I think it is because the trop and strat vortexes coupled strongly in mid December and have never looked back, it's still going strong now up there in the strat:

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GFS has the zonal winds going into the mesosphere (sic).  So looking for reasons beyond mid December seems a bit pointless to me, the damage was done before then and the +IOD is on the naughty step!

 

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The core of the precipitation is well into France on the ICON, the SE gets some rain and maybe a band of light rain, sleet in the Midlands:

iconeu-1-46-0.thumb.png.bf1edb293a3baef89927ffe0101f105f.png 

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12 minutes ago, Snowy L said:

Moderate snow for North Midlands on that.

South Midlands could hit the jackpot...penny slots though.?

 

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MetO is quite confident on the track of the low being south as their favoured model solution, straight through the channel.  Not bringing much in the way of snow, more like rain.  Saturday I would suggest is looking like a rain only event, no sign of anything white.  

 

 

Edited by Beanz
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GFS sticking to its guns, no real change up to the 48hr mark.  Looking good for the Midlands particularly:

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Then the risk moves south and east during the afternoon.

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Looks nice, but I certainly wouldn't put too much money on this being the final outcome!

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their is no bitter easterly or northerly  airstream  over the u.k. before this weather system moves in wed night,so no chance of a decent snow event,so even though the low is engaging cold air ithe air is nowhere near cold enough for a decent snow event.

Just about sums up this rubbish winter.

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GFS track at T45:

image.thumb.jpg.d13dde8bb6aca72aab85e577454e49d8.jpgimage.thumb.jpg.411cf832ba408427db859fd254a74f8d.jpg

Looks better for snow prospects than ICON to me.  I'm struck by the amount of uncertainty that still remains about this, it is unusual.  Looks exactly like a situation that is difficult to forecast, and surprises could very well happen.

Edited by Mike Poole
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The Arpege at 10:00hrs and 13:00hrs on Thursday.  According to this, still decent for Wales and the Midlands but pretty much a non event for the south and south east.  Not to worry, the GFS is always right at this range ?

image.thumb.png.e5323565fda3d6bd10cd24346b5b097b.pngimage.thumb.png.da369cf5020de37d141825e541de6d8b.png   

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I say its 50/50 for Thursday's possible event, there's been many marginal events that has been on the right side and has given a dumping to areas. With it being in the coldest part of the day over the Midlands particularly, wouldn't that be a factor of whether its rain/sleet or just snow? 

Also the 12z GFS looks a little colder on the northern edge of that system, may make more of it snowfall instead of Sleet/Rain but still mostly rain for the most part say from stafford/stoke south, but even areas south of that may get some very back edge stuff as it moves south and east with the cold coming south with it, but its still all up for grabs.

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Here we go, GEM take on things, similar to the other models, snow apx north of the M4 into the Midlands clearing SE.

 

 

 

 

 

 

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Edited by snowray
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Just now, feb1991blizzard said:

An Easterly!!!

image.thumb.png.20047c0efd87ea7c8e2537c6e280a7cc.png

Yes and typically too late and with no cold air to draw on ! 

These huge highs even in mid winter are too big for their own good , we want to see a chunk of the PV drop south to the east to inject some cold into the flow . 

Scandi highs boxed in are much better , bigger isn’t always better ! 

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