swebby

We still not had one this year? Surprised if so, thought Scotlnd has had one or was that named by the RoI met services? Problematic winds are often something overlooked with channel runners heading into the l8w countries, as they are such localised features.

Don't know - a dominant Azores high in March/April to my mind means it will bucket it down for the rest of the summer!

Was there not a super-nino event during this 90s? No idea if that has any impact if there was - well beyond my understanding! Edit - scrub that - misremembering! There were strong events for nino and nina but it was the very end of the 90's.

True, but if you are stuck under high pressure (very slack winds) and looking for an inversion to form, then the sea temperature is not going to have much impact beyond the coasts.

If we are optimistic, it would be this But then again, this is more likely

Yep, I think the fur/toys will be flying over the next few hours. Will come back this afternoon once it has settled down.

We are probably looking at only the last 15 years where the models have had sufficient resolution and reliability beyond day 5, so for the UK that's a limited number of events to look at. And..... from the mid 90s, there were hardly any noteworthy prolonged cold events in the UK anyway. For those more recent events 2009/10, 10/11 and 18. The models were roughly singing from the same hymn sheet 5 days out. When there has been disagreement between them, then the result has invariably been cold not reaching the UK, often instead diverting to somewhere south and giving a dumping of snow in Greece or even Spain! So in that respect the models have successfully called 12 of the last 4 cold spells...... The current disagreement however? To be honest, I'm not sure we've seen this before? I'd be curious to know if the current model iterations have run backforecasts from events pre 90s to see how well they fair? Edit - as you are new, i'd advise if you use the rule of thumb of "if the met office model output is not on board, then it ain't happening" then you will avoid a lot of unnecessary disappointment. And! Always pay attention to @johnholmes

GFS currently showing a very high impact event. My take? MetO have probably discounted it as a possibility but..... while the GFS and/or ensemble clusters still suggest it as a possible solution, then they will have to mention it just in case it comes off. If large parts of the UK find themselves in the freezer at the end of the next week and they've not mentioned it all well ahead of time - then that's a PR nightmare up there with "BBQ summer".

Plus some toys that can be played with to see what a pattern the hemisphere is predisposed to given x, y or z. Climate Prediction Center - MJO 200-hPa Lagged Composites WWW.CPC.NCEP.NOAA.GOV MJO monitoring and evaluation IRIDL.LDEO.COLUMBIA.EDU MJO monitoring and evaluation maproom MJO DS.DATA.JMA.GO.JP

I was wondering when they were going to get around to issuing these given rainfall forecast for tonight in the SW/Westcountry/S.Wales! Looking at the Fax charts, once the low clears through on midnight Sunday, we should have a chance to dry out.

It's a potential feature that is assumed could help trigger a sudden strat warming (SSW), which in turn may translate to a reversal of the usual flows in the troposphere in the polar region = high latitude blocking. No guarantee of cold from any of that, but some of the UKs bigger winter events, especially Easterlies, have come off the back of a SSW.

Very windy for the South and the West!

Always thought March was the month with the most snowfall potential? E.g. white Easters are more common than white Christmases. That the traditional snow potential in March does not actually take the form of what many on here desire - winter wonderland scenes - but is instead very short lived coverings that will have melted by mid afternoon is another matter! 2018 was a truly freak event to my mind. Wrt to those SSWs? Was it 2013 or 2018 where the flow reversal/response of the polar trop was so strong that the northern block went from the initially favourable position (for the UK) of Scandinavia to the unfavourable position of Canada in a matter of 3-4 days? That was astonishing and yet another example of what can go wrong with the synoptics in our neck of the woods will go wrong. Edit Just looked at some of the synoptics for 2018 - so i suspect it must have been 2013 that was the fail? https://www.metoffice.gov.uk/binaries/content/assets/metofficegovuk/pdf/weather/learn-about/uk-past-events/interesting/2018/snow-and-low-temperatures-february-to-march-2018---met-office.pdf

I've noticed over the past few winters that when in a zonal set up, the ECM op can be over keen on transporting waves of unmodified, very warm tropical air North eastwards, starting from the mid Atlantic, into the Eastern Atlantic and through into western Europe. Looking at the two ops this looks like one of those instances. Come the actual day however, while the pattern tends to be called correctly the air mass is heavily modified and the max temps are no where near to what was being shown 5-8 days earlier. I'm wondering if what we see here is the ensembles never going down this route of an unmodified air mass, showing up the ops tendency for that max temp as an unlikely outlier? I assumed this bug in the op is a bit like the historic tendency of the GFS to fail to pick out secondary low pressure formation in a trough at that time range, thus putting all the energy in one spot and creating those implausible dartboard lows.

I'm not sure it's an issue of limited historic data or current observations - I've always assumed it is just because such a set up is inherently unstable, which leads to a variety of computational solutions downstream, all of them seemingly viable. Normal climatic profile for the pole during winter is a vortex (low pressure) and so we should assume that is because it is the stable outcome. Solutions for what such a system will do next are predictable = reliable medium/long range forecasts. Go and stick a high pressure system in the middle of the vortex and instability has been increased, anything could happen and the probability of vastly different outcomes in respect to each other can only be clearly resolved in the short term. Hence the huge scatter in the ensembles, depending on where that high pressure finally ends up. Edit And just seen @Mike Poole post, which is saying similar - and i believe Mike models uncertainty, so knows his onions on that front.

A slightly tangential what if - But! What would the likely impact be for our Spring weather if we have strat PV @ +60m/s in late March?

That particular output, if you look at the hemisphere profile, has a polar high. Yes, the list of what can go wrong to prevent the UK finding itself in an artic sourced airmass is monumental, but to pick a model output that actually shows a polar high and then suggest there is no pathway to cold is a bit of a stretch? Under the usual winter hemisphere profile, height rises between the Azores and the Balkans are indeed a massive problem for those seeking cold, but the example you have posted there is not the common profile from the past two decades.

Not arguing with your analysis of the feature, i agree, it does look like a nuisance shortwave. But just to say it has been pointed out previously that the improved resolution of some of the models over the past few years means polar lows can now crop up in the solutions a lot further out than 48hrs. As to if they ever verify is another matter entirely.......

Is there a prize for the first mention of 62/63 synoptic patterns?

Excellent time lapse capture by a twitter user based in Cranbrook just to the west of Exeter, of this cell that was over me. Wind shear very clear, clouds going left right and centre in short space of time, also captures the barrelling downdraft to some extent. The twitter user may well be someone at the met office, which is just on the edge of Cranbrook.

Some very impressive wind shear on the the storm over Exeter, clouds going in every direction possible at some rate of knots with what looks like rotation to my untrained eye. Rolling thunder (cloud-cloud, no flashes) for the past 40 mins.

Unlikely if the location is as suggested, stuck in the middle of the weald, so it's well away from both the north and south downs. The discrepancy between there and Gatwick airport is odd - one of those readings must be off.

Well, it amused me.

Certainly agree with the wind speeds, but interestingly the actual impacts as listed on Saffir-Simpson are not that dissimilar. Cat #1 is - Very dangerous winds will produce some damage: Well-constructed frame homes could have damage to roof, shingles, vinyl siding and gutters. Large branches of trees will snap and shallowly rooted trees may be toppled. Mobile homes may be toppled. Possibility of coastal flooding. Extensive damage to power lines and poles likely will result in power outages that could last a few to several days. That is probably what we will get when you account for differences in US and UK infrastructure and building types. Cat 2 however is ott - that involves widespread damage to buildings.

No, i would not want it to go out at all! It was not the original post i was objecting to, it was the suggestion it should be pushed on social media. I've no issue with people getting excited (over excited in some cases?), or for giving their own forecasts and opinions to which they are perfectly entitled. But to stick a graphic on social media, that would certainly be mistaken as an official met office warning would be utterly reckless. Behind the scenes the met office will be currently advising the emergency services, local government, and national government of the potential life threatening outcomes. I'm quite sure they are busy enough as is without any "help" from us amateurs?