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14 minutes ago, tight isobar said:

Screenshoot (4 a bit of fun)

My assesment..

And poke it up wednesday morn.

?

Edit..

4 once i think its being UNDERHYPED!!.

and such as the met will upgrade warnings tmoz morn onward!!!!

Screenshot_2019-01-27-14-18-26.png

Not sure what your point is?I was just quoting the live weather update but whatever.good luck with your thoughts!!

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For those who think the SSW was a bust take a look at this at T+3   Then look at the NW/SE jet axis over us, then look at the fact that the downwelling has been delayed but is just und

Feel I have an apology to make.  If people are wondering why this thread vanished for almost an hour, basically I went ahead a locked the thread first. Then, went and hid it. Was feeling fed

Leaked express headline for tomorrow.   #sorrynotsorry

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Just now, Tim Bland said:

@bluearmy why does the downwelling response keep getting delayed? Didn’t this SSW happen about 5 weeks ago now? Are we really looking at 7-8 weeks for a response ?

No one knows Tim. Many have mused that the westerly QBO lower down in the strat has interfered or that this SSW is a slow burner type DSW.  unless Exeter lose their enthusiasm in the 30 dayer, I would stay optimistic 

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I find it ironic that whenever we get a cold spell in the mid-long term but nothing in the short term some people get all excited about the output... yet when we have potential snow events within the next few days people are complaining about the long range output!

What happens over the next week has a knock on effect for the week after so don't read into it too much yet. Just taking a look at the swingometers, the 5th of February for example still has some cold runs such as P7 which look good.

image.thumb.png.b587ef105eab9ba5e0e8aea97b24f27d.pngimage.thumb.png.91edd4420bc5b967f52523c0325abd46.png 

Not much blocking later on but there are some exceptions. P12 has a cold pool on our doorstep. The swingometers are milder but it is all very academic at this range, especially in the context of this weeks uncertainty. Look how much they flipped when we had the easterly fiasco!

image.thumb.png.6eea8f1d1ddb01b503b6b37f46338f5e.pngimage.thumb.png.def5499198c3cf9e49a988220a64ac47.png 

Globally we can see a cold NE Canada and warm USA which indicates a very active jet but I wouldn't be despondent yet. If the so called favourable background signals that have been around for the past month cease, maybe we will get a good cold spell? ??

image.thumb.png.a04e90897019986afcf309d3600f75f5.png

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4 minutes ago, Quicksilver1989 said:

I find it ironic that whenever we get a cold spell in the mid-long term but nothing in the short term some people get all excited about the output... yet when we have potential snow events within the next few days people are complaining about the long range output!.

 

If the so called favourable background signals that have been around for the past month cease, maybe we will get a good cold spell? ??

 

No complaints - but realistic about the likely limited impact of the events this coming week. A small swathe of the south may do ok out of it, but there will be rain in the mix too and uncertain precipitation amounts. And there seems little prospect of entrenched cold to prevent melt. The last time we had a channel low/slider that gave significant impact it was Feb 96 to my memory - but we had a block in place that stalled the advancing system. This isn't going to happen this time, and the snow will not hang around.

Your last point is counter intuitive despite the smilies. If the signals fade then so does the chance of cold. We certainly don't want that - a lot is riding on those signals.

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11 minutes ago, Catacol said:

No complaints - but realistic about the likely limited impact of the events this coming week. A small swathe of the south may do ok out of it, but there will be rain in the mix too and uncertain precipitation amounts. And there seems little prospect of entrenched cold to prevent melt. The last time we had a channel low/slider that gave significant impact it was Feb 96 to my memory - but we had a block in place that stalled the advancing system. This isn't going to happen this time, and the snow will not hang around.

Your last point is counter intuitive despite the smilies. If the signals fade then so does the chance of cold. We certainly don't want that - a lot is riding on those signals.

I think there is too much uncertainty to say impacts will be limited, Tuesday's low will probably be a bit too far south but there are still some runs which send it further north. Thursdays low is also very uncertain so I think we should sit on the fence. Further afield, If the output can suddenly flip mild for the easterly it can do the reverse... especially when we are talking about the medium time range.

With regards to the background signals they have had little to show so far. The SSW for example is still being sluggish. We may see an easterly in March but then again, easterlies are more common during Spring anyway... They may hold some importance but I never hear proponents of them admit they are wrong.

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1 minute ago, Updated_Weather said:

Anyone going to comment on the ICON12z? Further south.. Interesting still for southerns:)

Tis' indeed further south but that wave feature to the north of the low is still present.

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Yes the LP is a little weaker and hair south.

However its now looking increasingly clear that it will be the active cold front coming in from the west that will be giving us the snow. This is more or less identical in postioning and strength as previous runs...so I feel like the 12z suite will likely confirm the likely scenarios with this.

Thursday's low looks abit more square on, which would suggest to me a more northerly based run than the 06z run was...but we will see!

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2 minutes ago, Updated_Weather said:

Anyone going to comment on the ICON12z? Further south.. Interesting still for southerns:)

Think it's heading into France tbh

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Indeed the ICON 12z is a touch south, but the features over the UK remain and the outcome is relatively similar. For the system on Thursday the low remains a little shallower at the moment and so less warm air is dragged into the system.

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22 minutes ago, Tim Bland said:

@bluearmy why does the downwelling response keep getting delayed? Didn’t this SSW happen about 5 weeks ago now? Are we really looking at 7-8 weeks for a response ?

Th SSW was a displacement one followed by a split as the second wave bullied the SPV into three daughter vortuies - one wee one and two larger ones.This happened around Christmas so you're right on that score - lots to be gleaned by looking at this thread...

As no two SSW's are identical as many people keep saying, the speed of downwelling to affect the troposphere, if it occurs, can vary from a quite quick response to a much delayed one. This all depends on the factors at play, positioning of the displaced SPV, QBO, MJO, GWO and probably a dozen more TLA's (three letter acronyms) which all go into the mix. I can't recall if the SSW in 2013 was a fast response or not but the March it delivered for us was epic, and we even had an ice day on April 1st, which is pretty good going. 

The trouble is with NWP, the output is based upon scenarios resulting from a specific set of data inputs interacting with algorithms. When the data changes, and as the effects of the SSW down well, that data will change, it can give false signals which, being computers and working on logic, brings different resulting outputs and hence the models flip, flop and do the hokey cokey with GPH, troughs and all the other associated weather features.

At least it's trending cold for this next week, after that I wouldn't bet the farm on anything other than it'll go dark at night.

 

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Conversely the ICON has the low/frontal system further north than the 06z suite. The main difference is there is a real lack of secondary lows on this run so the system has nothing to tug it into a shape that is better for the south, so the front remains square on and flat N-S which is pretty killer for the south and will mean we will import milder air from the channel.

Still plenty of time for changes on Thursday's track, as Tuesday's low is showing right now!

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5 minutes ago, kold weather said:

Yes the LP is a little weaker and hair south.

However its now looking increasingly clear that it will be the active cold front coming in from the west that will be giving us the snow. This is more or less identical in postioning and strength as previous runs...so I feel like the 12z suite will likely confirm the likely scenarios with this.

Thursday's low looks abit more square on, which would suggest to me a more northerly based run than the 06z run was...but we will see!

Tuesdays runner is turning into a diver which has more chance of affecting the french rather than English riviera ! 

Anyway, that Tuesday trough is getting a bit narrower by the run! 

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4 minutes ago, bluearmy said:

Tuesdays runner is turning into a diver which has more chance of affecting the french rather than English riviera ! 

Anyway, that Tuesday trough is getting a bit narrower by the run! 

I think we are losing some of the stuff in front of the cold front that was pushed up from the LP core itself. That's probably no bad thing as the stuff in front of the cold front was always very marginal anyways so more of the front is snow (especially the further west you go). I'd be more worried if the timing started moving up more.

Of ourse this is just one run, we'd be wise to hold fire until after the ECM before being totally confident! 

Edited by kold weather
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3 minutes ago, bluearmy said:

Tuesdays runner is turning into a diver which has more chance of affecting the french rather than English riviera ! 

Anyway, that Tuesday trough is getting a bit narrower by the run! 

Indeed. Actually not much in the way of snowfall so it does seem to tie in with the metoffice warning of 1-3 cm. I suspect the front will be quite patchy.

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4 minutes ago, bluearmy said:

Tuesdays runner is turning into a diver which has more chance of affecting the french rather than English riviera ! 

Anyway, that Tuesday trough is getting a bit narrower by the run! 

...........hopefully the LP for Thursday can move a little further south too then?

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ICON 1st low: anim_iuo2.gif

Should get 1.5 - 2.5 hours of snow out of that but with each run, the LP slipping further south this front will get weaker and not really as promising for the south as we hoped. Zero chance of the low coming anywhere near the UK and the second low is not going to be close, for snow, for the M4 south, so just hoping this run is not the trend.

Edited by IDO
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46 minutes ago, bluearmy said:

No one knows Tim. Many have mused that the westerly QBO lower down in the strat has interfered or that this SSW is a slow burner type DSW.  unless Exeter lose their enthusiasm in the 30 dayer, I would stay optimistic 

I agree , the one thing is the MO have been constant , they are probably thinking its not if its when , and its taken a tad longer...…….I hope that's right anyhow 

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