IanT

18.5c according to my car just now..!

An outstanding idea for those tasked with promoting the climate crisis concept.

I’ve discussed this before - it’s what I call the “mostly harmless” problem. Whilst [low prob x high impact] and [high prob x low impact] are the same in EV terms (so useful for insurers etc) they aren’t the same when preparedness is the key outcome. In simple terms these two axes shouldn’t be reduced to one dimension (colour) because too much valuable information is lost in the final transformation. I like the matrix, but not the colour overlay. Perhaps retain the matrix but go with a “PxI” labelling system where P(Probability) is Low(L), Medium(M), High(H), Very High(V) I(Impact) is Low(1), Medium(2), High(3), Extreme(4) So Isha would have been “upgraded” to an V4 for a limited area late last night. Why? Because most people don’t need to make special preparations for high probability / low impact events, but they should for a low probability / high impact events. At the moment these two scenarios both end up being called Amber. That’s where the loss of valuable information occurs.

Agree 100%. The most impressive aspect of this storm (so far, I am mindful of the red warning just out) is the sheer scale of the wind field. Across southern Britain - based on posts here and my experience driving from Surrey to S Wales between 1900 to 2120 - the intensity has perhaps been unremarkable. Some strong gusts and rainfall but not out of the ordinary.

Living the dream

I’ve driven from Woking to Cardiff this evening. A bit wet & windy across the Severn, but otherwise unremarkable.

GFS saying 102kph gusts for Cardiff, wildly out of line with the other models. Latest METAR says gusting 36kts (67kph).

It’s winter here in the UK. A storm can be a storm without being historic. A cold spell can be a cold spell without being historic - as we have just seen. Would it benefit us to return to a time when forecasts were forecasts without hype?

-6c here this morning. That’s cold for my location.

Alternative viewpoint: if anything is wrong - or anything changes - with the current NWP forecast output there is potential in all directions. Time for some butterflies somewhere to flap their wings

In the investment world we recognise what is called the “pain trade”. It’s the outcome least expected/favoured by the majority of forecasters; the outcome that few forecasters expect or want and that even fewer are positioned for. It’s pretty clear that the pain trade here - for both the NWP models and NW’s forecasting community - would be for the SE (& London in particular) to get buried later this week. The “French low” tracking N to deliver a headline dominating Cobra-level snow event in the most heavily populated portion of the country… Pain trade outcomes occur more frequently than expected, because outcomes in the tails of distribution approximations are - by definition! - unusual and hard to forecast. That’s why experienced/canny forecasters like the MetO take great care to allow some space for tail outcomes in their forecasting language. I think we can see that in action here…

…but 11 days away!

You make the mistake of discussing the actual weather. This thread is only for discussing the weather in the models

Plenty of forecasts made here, but I haven’t seen anyone making promises. Almost without exception posters say “The models show…” or “If this chart verifies…”. Interpreting such statements as promises is such a needy and immature character trait…

Too early for that! Clearly plenty here who are still looking/hoping for a good lynching opportunity

This “event”, this thread. Surely the longest/worst/best chase in the history of NW…! RPReplay_Final1670488555.mov

This. It has long been my view that the MetO aren’t any more precise with their forecasting than many of the excellent posters here. They are far more precise with their use of language though, and particularly disciplined in their deployment of “terms of estimative probability”.

I think “almost certain” is too definitive / strong a phrase.

100% agreed!

Thank you. Sadly the y-axes are scaled differently so it’s hard to construct the time-shifted overlay I had in mind.

Is there a way to view this ensemble chart as it was 7 days ago? I think it would be instructive to compare last weeks iteration with this one, but I don’t know how to do that. Can anyone help?

Looking back in this thread to last Wednesday - where discussion of Cobra meetings and 1963 was commonplace - so much has changed. The cross-model consistency that highlighted a supposedly predictable progression from the current cold snap into a more prolonged GH episode has all but evaporated. The extended/deep cold spell kicking off on @Scott Ingham day isn’t now the well-backed central scenario it was. If it is it has something of Trigger’s broom about it, with many new parts. A fascinating period of model watching.

First mention (I think) of “snow fields” has given me a line on my NW bingo card

It’s probably a cold outlier. This run is for the bin…

So the reputation of GFS has been fully rehabilitated today. It’s a great model and we should favour its output? just trying to keep up…