[Storms and Convective discussion - May 2024]

 weatherobsuk Newlands Corner in Surrey might work for you…

[SE, London and East Anglia Weather Discussion - Dec 2023 on]

18.5c according to my car just now..!

[#NameOurStorms: is it a good idea?]

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

[Storm Isha, Amber ⚠️]

6 hours ago, Paul said:

I agree that the matrix is an important part of the warnings. But, I'm wondering whether you're more highlighting an issue in the communication of the warnings and the matrix system itself, rather than anything else. I mean, if so many people aren't reading the warnings properly and potentially misunderstanding them, is it their fault or the warning's fault?

A warning ought to be as crystal clear as possible from the headline really, if you need to delve into the inner workings to see what's going on, I'm not sure that's ideal. 

Not Meto bashing by the way, as it's a difficult thing to get right, but the one thing a warning system ought not to be (imo) is confusing. 

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.

 

[Storm Isha, Amber ⚠️]

4 minutes ago, bradymk said:

Strongest gusts so far in Cardiff now. Nothing too unusual for here, but size of the wind field clearly impressive.

An upgrade in wind speeds on latest 21z UKV for NE Scotland, particularly right at the coasts. Perhaps explaining the red warning here.

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.

[Storm Isha, Amber ⚠️]

2 minutes ago, sunnijim said:

So true.

A heady combination here  of wild gusts, the wife snoring, and cat meowing as I lie in bed eating chocolate.

Living the dream

[Storm Isha, Amber ⚠️]

3 hours ago, IanT said:

GFS saying 102kph gusts for Cardiff, wildly out of line with the other models.

Latest METAR says gusting 36kts (67kph).

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

[Storm Isha, Amber ⚠️]

GFS saying 102kph gusts for Cardiff, wildly out of line with the other models.

Latest METAR says gusting 36kts (67kph).

[Storm Isha, Amber ⚠️]

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?

 

[SE, London and East Anglia Weather Discussion - Dec 2023 on]

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

[Model Output Discussion - Colder but how cold and for how long?]

30 minutes ago, Man With Beard said:

The ICON accumulated precipitation chart up to Saturday is a bit of slap in the face for snow lovers in central and southern areas - precipitation virtually everywhere in the Atlantic and Europe apart from here!

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

[Model Output Discussion - Colder but how cold and for how long?]

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…

[Model Output Discussion - Colder but how cold and for how long?]

Just now, Purga said:

Ugly - with a screaming jet right over us.

…but 11 days away!

[Model Output Discussion - Colder but how cold and for how long?]

4 minutes ago, ribster said:

To be fair I don't understand this either, it's been cold since Friday last week, snowed Monday and frosts several nights.

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

[Moans, ramps and banter]

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…

[Model Output Discussion - Colder but how cold and for how long?]

 

5 minutes ago, london-snow said:

Give this lad a lot of credit guys and girls. Never been too far away in a landing zone. Well done Scott

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

 

[Model Output Discussion - Colder but how cold and for how long?]

This “event”, this thread.

Surely the longest/worst/best chase in the history of NW…!

 

 

[Model Output Discussion - Colder but how cold and for how long?]

3 minutes ago, Hammy79 said:

They can only go off the data that they have in front of them at the time and hence why its highlighted as a risk rather than a dead cert. 

The GFS 6Z takes the system just south of the UK and wouldn't take much to bring that Risk back into play. 

Anyway,

Much better from the 6z for longevity- lets see where it takes us further on 

 

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”. 

[Model Output Discussion - Colder but how cold and for how long?]

Just now, January Snowstorm said:

What surprises me is the Met Office more or less went for the low pressure to be further North. Its almost certain now that won't happen 

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

[Model Output Discussion - Into 2024]

4 minutes ago, Scott Ingham said:

If we got cold weather and snow 15th to the 23rd I’d be over the moon with that especially as February looks interesting if not more interesting with angular momentum on the rise again from a much higher base state and further weakening if not ssw higher up!

100% agreed!

[Model Output Discussion - Into 2024]

6 minutes ago, Met4Cast said:

Here's the GEFS from the 1st January

Not sure there's any archive just had this saved for some reason.

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

[Model Output Discussion - Into 2024]

6 minutes ago, Purga said:

Been alluded to but some very good cold runs in the ENS. Also, a VERY encouraging & bullish UKM long range update today for coldies (check out the appropriate thread) !

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?

[Model Output Discussion - Into 2024]

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.

[Model Output Discussion - Into 2024]

3 minutes ago, Frigid said:

GFS 12z has produced possibly one of the most severe winter charts I've ever seen, this would rival the likes of 2010, 1987, 1979. On snow fields, those figures could easily dip below -20C.. fantastic run for cold. 

  

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

[Model Output Discussion - Into 2024]

Just now, steveinsussex said:

But where does it sit in the ENS

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