West is Best
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Posts posted by West is Best
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A deep freeze 6z run with the first signs of proper cold pooling in Europe: something which has been remarkably lacking in recent years (climate change):
I still think the evolution to this however looks precarious and I urge caution for everyone's sanity.
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Just now, Daniel* said:
they showed a U.K. high on their day 10 forecast. We are not going to see a UK high.
A very rash remark indeed for the reasons I have just posted. I would say it's 60:40 we will indeed have a toppling high.
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Another word of warning about this easterly. The risks inherent in the evolution from this:
to this:
... are considerable.
It doesn't mean it won't happen but 'nailed on' it most certainly isn't. We await with bated.
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Squally heavy rain on the Cornish clifftops. Not surprised that it's rain although some of the heaviest snowfalls I've seen in recent times have been in Devon. All too marginal this time around for most people at low levels in the south but I wish great joy to those who get lucky.
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27 minutes ago, KTtom said:Solid agreement for the high to be aligned perfectly for an easterly feed,
There might come an easterly out of this but words about 'solid agreement for a perfect alignment' make me nervous. The progression of the high pressure cell towards Iceland is a precarious synoptic setup at the best of times. A small shift and we find ourselves under a high pressure not an easterly and many, many, many times easterlies have been promised even at short notice only to come to nothing (John Kettley's infamous beast from the east being the classic example).
The models have generally trended more cold over the past 24 hours but only by a notch. My concern is that there remains a lack of 1. robust upstream blocking and 2. significant cold pooling to our east, although this has improved slightly. It should also be noted that later on in the run 0z GFS has a south-easterly veering southerly: in fact what Steve Murr used to call the backdoor exit from a cold spell. This is because it has the hp evaporating. That also needs to be watched as it's a relatively new development with the GFS which has continued to be all over the place past T168 - another reason to be cautious. In addition we should note that in FI models are continuing to show Atlantic low pressure cells and without robust upstream blocking this should be a cause for concern. It can, of course, be the prelude to proper snow: when a low pressure collides with cold pooling and the undercut leads to real snow. We are a long way from that scenario at the moment. The 0z ECM indeed has the hp cell eventually moving so far north that the cold uppers over the UK lift from the south: we lose the cold source.
These setups are precarious. I can only really remember one perfect alignment for an easterly and that was February 1986 - one of the three coldest months of the C20th I believe but one hardly anyone remembers as it was simply cold. No snow. Just bone chilling boring dry cold.
At the moment I see evidence to stick with the Met Office that we're in for a week of cold weather, with rain, sleet and snow but also a lot of dry weather. Temps below average but nothing seismic or significant. Pretty much in line with the kind of below average conditions we experienced in July and October. Beyond T144 at the moment is unclear and uncertain. Caution should be the watchword not over-enthusiasm. At least for now.
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I've stayed away from posting on this thread because I haven't wanted to annoy people and it becomes a bit of a religion on here sometimes. However, this has never looked in the models more than a relatively slack 6 day cold snap. There will be some wintry precipitation even to low levels. But there's still nothing sustained showing up. There has been little or no robust upstream blocking and a notable absence of deep cold pooling over Europe: something I note as a feature of climate change.
UKMO goes for a toppling high as did yesterday's ECM and now the GFS shows a return to zonality. So that's all big three models going against any sustained cold spell.
It's there in front of us in the model outputs whether we like it or not.
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2 hours ago, Mapantz said:
Does anyone else get like a headache when the pressure drops rapidly? My eyes and head feel like a balloon being squeezed.
Yes I get that too.
That was a wild night.
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I'm on a Cornish clifftop. The first house for 3400 miles and right now I'd rather we don't hit 90 mph if it's all the same
It's so wild out there. Really quite scary.
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It's so wild out there. Crazy.
81mph recorded at Aberdaron so already exceeding the Met Office forecast of 70-80 mph.
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3 minutes ago, snowrye said:
Soz, waffled on a bit there didn't I, I meant I'll be up to hear it, normally I sleep through these events lol
No you didn't waffle. I was just worried that you are okay.
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A little video from earlier this afternoon on the Cornish clifftops as Bella announced her arrival
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4 minutes ago, snowrye said:
Im currently on my mum and dads armchair, which is where i've been for the last 18 nights, icy decking and ribs, say no more, not slept in all that time, so tonight could be fun, I wonder what will go for a burton 1st, stay safe all
Not sure the backstory but I hope you are okay?
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Incidentally, this isn't out of the blue. Different times of year but we had a cold northerly July and again in October.
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5 minutes ago, KTtom said:
what is stark is how many attempts the Atlantic ridge makes at getting into Greenland,
As a matter of interest, can this ever happen? I'm pretty sure we debated this once and the hp cell over Greenland is always distinct from the one in mid-Atlantic. They never truly join? Correct me if I'm wrong but I'm sure that's been stated on here even by Murr.
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The ever-present threat of high pressure rebuilding is becoming more clear in the GFS ensembles and now apparent in the ECM operational. As it's the form horse it would be unwise to dismiss the possibility.
This might be reverse psychology for my self-protection but at the moment I remain of the view that we are likely to see several days of colder conditions with perhaps a little snow to low levels for some fortunate people. Nothing substantial or seismic before settled conditions prevail ahead of the next Atlantic reload. It will make the first half of January cold.
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If you want a bit of a giggle watch the lovely Louise Lear right at the end of the latest forecast
2:22 onwards
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I've been keeping off here because I haven't wanted unintentionally to annoy people.
However, in the interests of balance I have to post this as it has been showing up for days and days. If anyone tells you that the really cold scenarios after Boxing Day are 'nailed on' then there are three significant reasons why I don't yet believe it.
1. We always get this and they always downgrade. Without exception.
2. The upstream blocking still doesn't look sufficiently robust to me. Whether it's the mid-Atlantic High holding in place or retrogressing into Greenland, neither remains for very long and that's, frankly, a recipe for trouble.
3. Most significantly the ensembles continue to show a significant number of members bucking the trend. This from the 6z where, once again, the operational is running below the mean:
I'm sorry to appear like a party pooper and I hope I'm wrong.
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14 minutes ago, The PIT said:The cool/ rather cold start to December at one point looked likely to last longer before the models suddenly flipped.
I didn't think it looked at all likely. Why so? Because there was no upstream blocking: people were relying on the high pressure in Russia / Scandinavia to turn into sustained blocking here and that's a fraught pathway to cold in the UK. Looking east not west is like beginning a book on the last page and reading backwards to the start. It can be done but it's sub-optimal .
This time there's upstream blocking showing up: a proper Greenland High which is very different.
Doesn't mean it will happen, mind you (so I agree about that), but at least the starting position is on much firmer ground. Damn the flow upstream first and watch the results. This is a cracking chart:
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7 minutes ago, mb018538 said:
I probably just phrased my answer wrong - I was agreeing (in a rather unclear way) !
Haha no worries! If this kind of model run appears with 72 hours to go this place will be chaos and we'll all be posting and replying in a febrile state!
Fingers crossed, although John Holmes may need to remind us that we should be careful what we wish for. A 1947 or 1962-3 would be a sucker punch for a lot of people after this year. Not for most of us on Net weather model output discussion though
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3 minutes ago, mb018538 said:
Believe me - I've seen many major outliers in my time here.....this isn't one of them!
Which is presumably why I stated that it is not an outlier. Or did you rush to reply before reading properly?
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The first properly exciting model run of the winter. The first one to make me sit up. Notice the all-important Greenland High. Upstream blocking is the key, which wasn't present in previous flashes of cold.
It doesn't have great support but neither is it an outlier. Something to watch.
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A particularly stormy 12z GFS. If that came off it would cause a large amount of chaos. There's a vicious storm on Christmas Eve but the real humdinger is reserved for Dec 27th/28th. Would be nigh-disastrous.
The GFS does this regularly: wildly over-ramping Atlantic and polar storms only to downgrade, sometimes at the last minute.
However ... just in case you think this couldn't materialise at this time of year I can still vividly remember the infamous storm of New Year 1976 "The Capella Storm" which caused chaos across the UK and especially Europe. It killed c. 100 people, 24 of whom were in Britain:
Gale of January 1976 - Wikipedia
EN.WIKIPEDIA.ORGSo this chart is very similar to those synoptics and would be pretty dramatic:
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27 minutes ago, swfc said:
I'd suggest anything going forward is probably going to come from the nnw. Atlantic ridging ete looks the form horse with the jet going sse. Possibly into early January but has folk have said very fluid output
I think this post nails it.
I'd only add that there's the ever present risk of a return to flat zonality but, if not, then this is likeliest scenario and one we've seen all too often in recent years. Not bad for Scottish ski resorts when the gales abate enough for the lifts to open. Any sustainable block looks very unlikely to me and there is a notable absence of cold pooling in places which once upon a time we could bank as certainties: over Russia into Siberia and Scandinavia, even Eastern Europe. It's just not there at the moment.
I feel like we are Canute before the incoming tide. There's no escaping the fact that climate change has altered our winters.
Don't shoot me. It's not my fault.
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The likeliest progression is that a couple of days before the colder snap the 'northerly' will get slacker and slacker and turn into a damp squib. The ECM points the way here I suspect.
Sorry to be a grinch but we've all seen this sooooooooo many times. It needs to pep up considerably for the inevitable downgrade to retain potency.
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Model Output Discussion - Into the new year
in Forecast Model Discussion
Posted
This may fall on deaf ears but I continue to urge caution. The easterly scenario is by no means nailed on. With these ensembles I continue to think it's 60:40 high pressure will settle (topple) back over the UK after the northerly: