IanT

I recognise that these are parochial terms, but could someone please offer a rough reminder / definition of each for those of us who have missed a few posts along the way...?

Good spot / interesting post. Thank you...

Wind, rain and moped muggers.

Unremarkable here in Surrey so far. Wind still has a large southerly component. I’ll be watching as the day develops though.

Promised..?

...missed parts of Surrey...

The radar looks like it did during the Dec 2010 streamer. Is my interpretation reasonable?

Volleyed and thundered, stormed with shot and shell....

4cm of somewhat wet snow that’s melting rapidly here in Woking. Like a night with Kylie Minogue (or George Clooney, as you prefer) the anticipation was perhaps better than the reality...

Temp here in Woking has fallen from 2.9c to 1.2c in the last 90 mins or so. Humidity per my Vantage Pro is 47%. Good!

Looks ok to me.

A little colder here (Woking) than was generally forecast. -6.3degC and still falling. Can’t hurt..!

That’s two posts containing charts with no date & time on this page alone....

Terrible performance? What is going to happen next week may well have changed. To suggest that a forecast updated by 48h more data is “terrible” is a viewpoint underpinned by an implicit assumption that the weather is a deterministic system in which no randomness is involved in the development of future states. A deterministic system being one that will always produce the same outcome from a given starting condition or initial state. But I think that we all understand innately that weather is far from deterministic. There are chaotic elements - the proverbial light left on in Fairbanks etc. - which influence outcomes. As forecast horizons extend the scope for these to have an impact increases. Given a specific set of starting conditions, multiple outcomes are possible. The weather that we get is one realisation, but there may have been other equally plausible outcomes at the point the forecast was made. Criticism of NWP outputs on this board (and others!) often follows a pattern. Posters will say that the models are "struggling to tie down" a feature, or that the models are "always poor in this type of setup". With the benefit of 20/20 hindsight, posters will say the model was "wrong because it failed to pick up ... [height rises over the Azores?]". Any verification gap is thus attributed to modelling weakness/failure, overlooking the possibility that something changed between the point at which the forecast was made and its realisation. What is the point of all of this? I guess it's a plea for acceptance that the models aren't "searching for a solution". We shouldn't criticise them when they "flip-flop" from one outcome to another, especially where longer time periods are involved. There simply isn't one path that the models have to "lock-on" to. Weather has chaotic elements. If the models this afternoon don't show the extended cold spell they were showing yesterday it might not be because they are inaccurate. Something might well have changed! NWP models are wonderful tools for forecasters. I'm sure that they have massively improved forecasting accuracy in recent years, and that these improvements will continue. But we should always remember that weather is not a deterministic system, and modulate our expectations and responses accordingly.

As this all happens before March 29th, we’re in.

“...rock solid...”? Whilst I understand and support the sentiment behind your post, I think “...rock solid...” is WAY too strong a phrase for UK weather that is still 12 days away...!

Thank you - most appreciated. Meridional and zonal flows are concepts with which I am familiar. Your explanation is helping me fill a few gaps. So “height” (in this context) refers to south-north distance on the map, as opposed to height above the earth’s surface?

The term "amplification" is used regularly in the hunt for cold thread. Could someone please explain what it means..? What is being amplified and how? Here's an example: "The 6z gfs starts less amplified than the 0z but somehow manages to amplify more than the earlier run by 120 hours."