[Misc] The Award-winning official "More Snow Tomorrow?" Thread [2024-25 Season]

[Audax]

The only wrinkle at this range is the ECM Op run which keeps the high pressure too far south, so the worst / best of the cold air goes to our south. Need to check where on the ensemble set this run sits to understand its significance.

As much as I know it'll change 50 million times before we get there, the netweather.com forecast for Uckfield for next week is a thing of beauty. Snow most of Monday, then all of freaking Tuesday (and an ice day to boot), most of Weds, a bit more Thurs night.

Of course, now I've mentioned it it's not gonna happen, is it?

 

[Papa Lazarou]

As much as I know it'll change 50 million times before we get there, the netweather.com forecast for Uckfield for next week is a thing of beauty. Snow most of Monday, then all of freaking Tuesday (and an ice day to boot), most of Weds, a bit more Thurs night.

Of course, now I've mentioned it it's not gonna happen, is it?

The ECM ensemble shows that the Op was on the mild side.



Also, the latest GFS has the snow possibly starting here from Sunday lunchtime, with some very cold air.

 

[Audax]

Also, the latest GFS has the snow possibly starting here from Sunday lunchtime, with some very cold air.

I looked at the forecast on netweather first thing this morning, and it said the same - 95% chance of snow around Sunday lunch time. Went back a couple hours later and it was gone ... replaced by a balmy 1*C and bright sunshine. Will be keeping an eye on it, and flagging it with my boss as could very likely mean I'll be working from home all of next week if this verifies.

 

[Weststander]

"Monday onwards I will leave for now, as the details will change, but in general I'd suggest the most likely outcome is day time max temps of 1 to 2C, with some places at or below freezing. We will see an increasing chance of snow either from showers, or depending on synoptic details, longer periods of snow at times. Night time temps will be well below freezing where we see clear skies and close to freezing under any cloud / snow in a NE / E wind.

Forecasting snowfall is pointless at this range, as the best falls often come from small scale features that arise at short range, so let's just say there's potential.

I would see this cold spell last at least 3 or 4 days, but it could extend longer."



@Papa . The BBC is forecasting max temps of 4C for Brighton next Monday/Tuesday/Wednesday, with a very low probability of any precipitation at that time, with the same for towns just the other side of the South Downs. Your winter forecasts often appear snowier and colder than theirs. Have you found that the forecast data you use ends up better reflecting the eventual weather?

 

[Audax]

@Papa . The BBC is forecasting max temps of 4c fo Brighton next Monday/Tuesday/Wednesday, with a very low probability of any precipitation at that time, with the same for towns just the other side of the South Downs. Your winter forecasts often appear snowier and colder than theirs. Have you found that the forecast data you use ends up better reflecting the eventual weather?

BBC recently changed to a new supplier for their forecasts. From what I've heard they're using the ECM model outputs to produce their forecasts. At the moment, the ECM is one of the "warmer" models as it thinks the worst of the cold will slip south of the UK. The GFS and other models are currently on the colder side. Lots of uncertainty still - it's going to get cold, but exactly how cold, and whether or not it supports snow, we won't know for a few more days.

 

[Papa Lazarou]

"Monday onwards I will leave for now, as the details will change, but in general I'd suggest the most likely outcome is day time max temps of 1 to 2C, with some places at or below freezing. We will see an increasing chance of snow either from showers, or depending on synoptic details, longer periods of snow at times. Night time temps will be well below freezing where we see clear skies and close to freezing under any cloud / snow in a NE / E wind.

Forecasting snowfall is pointless at this range, as the best falls often come from small scale features that arise at short range, so let's just say there's potential.

I would see this cold spell last at least 3 or 4 days, but it could extend longer."



@Papa . The BBC is forecasting max temps of 4C for Brighton next Monday/Tuesday/Wednesday, with a very low probability of any precipitation at that time, with the same for towns just the other side of the South Downs. Your winter forecasts often appear snowier and colder than theirs. Have you found that the forecast data you use ends up better reflecting the eventual weather?

I find the BBC tend to err on the milder side at range and tweak it as they get closer. Just to check, is that the Online BBC 5 day forecast or an actual forecast with a person etc?

The only reason I ask is that the automated 5 dayer has no 'human' input and just represents the raw data from 1 run from 1 model, which makes it prone to inaccuracies and swings.

 

[Papa Lazarou]

BBC recently changed to a new supplier for their forecasts. From what I've heard they're using the ECM model outputs to produce their forecasts. At the moment, the ECM is one of the "warmer" models as it thinks the worst of the cold will slip south of the UK. The GFS and other models are currently on the colder side. Lots of uncertainty still - it's going to get cold, but exactly how cold, and whether or not it supports snow, we won't know for a few more days.

And that. I forgot that they used the ECM now, which as you say, tallies perfectly with the milder ECM run today and yesterday

 

[Weststander]

BBC recently changed to a new supplier for their forecasts. From what I've heard they're using the ECM model outputs to produce their forecasts. At the moment, the ECM is one of the "warmer" models as it thinks the worst of the cold will slip south of the UK. The GFS and other models are currently on the colder side. Lots of uncertainty still - it's going to get cold, but exactly how cold, and whether or not it supports snow, we won't know for a few more days.

Have you noticed a pattern where several forecasting models, invariably forecast a greater likelihood of snow and lower temperatures, than the ECM/BBC data?

I follow this thread, as well as some websites than use GFS data, and over time the BBC forecasts seem to be milder and less snowy for SE England.

 

[Audax]

Have you noticed a pattern where several forecasting models, invariably forecast a greater likelihood of snow and lower temperatures, than the ECM/BBC data?

I follow this thread, as well as some websites than use GFS data, and over time the BBC forecasts seem to be milder and less snowy for SE England.

The netweather community has been saying a lot of late that the ECM model hasn't been the most accurate for most of this winter so far - GFS has largely done a better job. Having said that, the effects of the SSW has given *all* the models a major headache. There's been a lot of flip-flopping. There's been some comments shared on netweather this morning that some forecasters on the continent think the ECM currently has "got it wrong" and is holding the cold air too far west for too long, and expecting the ECM model to correct itself tonight.

 

[Papa Lazarou]

Have you noticed a pattern where several forecasting models, invariably forecast a greater likelihood of snow and lower temperatures, than the ECM/BBC data?

I follow this thread, as well as some websites than use GFS data, and over time the BBC forecasts seem to be milder and less snowy for SE England.

I think it varies - the problem is the websites that rely on the Operational run for ANY model,, without any analysis.

For example, the ECM Op has been towards to the top of the ensemble for the past 2 days (in terms of surface temps) and therefore pages processing that raw data will give skewed outlook. The same applies to those that use GFS data, although the GFS Op has been firmly in line with its ensemble for the past 24 hours.

The best forecasts review ALL available data and make a judgement; which is what I hope I do... although I do WANT snow!

 

[Napper]

I find the BBC tend to err on the milder side at range and tweak it as they get closer. Just to check, is that the Online BBC 5 day forecast or an actual forecast with a person etc?

The only reason I ask is that the automated 5 dayer has no 'human' input and just represents the raw data from 1 run from 1 model, which makes it prone to inaccuracies and swings.

That's very interesting and explains how hard it is to predict I guess.

Rarely use the BBC 5 day forecasts now as they change constantly and its pointless looking.

 

[Papa Lazarou]

That's very interesting and explains how hard it is to predict I guess.

Rarely use the BBC 5 day forecasts now as they change constantly and its pointless looking.

There are times (like the past week) where the models have really struggled to process the impacts of the SSW, and in these cases forecasting becomes VERY hard. At times the upper air temp spread at even 5 day range was up to 20C, which illustrates the uncertainty. In such a scenario any automated forecast might show snow and 2C for a specific date and then 12 or 6 hour later 14C and sun.

Even in such uncertain periods the inclusion of an actual forecaster in the mix makes such a difference.

 

[Papa Lazarou]

The netweather community has been saying a lot of late that the ECM model hasn't been the most accurate for most of this winter so far - GFS has largely done a better job. Having said that, the effects of the SSW has given *all* the models a major headache. There's been a lot of flip-flopping. There's been some comments shared on netweather this morning that some forecasters on the continent think the ECM currently has "got it wrong" and is holding the cold air too far west for too long, and expecting the ECM model to correct itself tonight.

West? Do you mean East?

 

[Audax]

I notice everyone's favourite grumpy Uncle has been rather quiet now that even the BBC are showing pretty cold temps for next week (Uckfield day time max of 2*C for the 27th). That's a good bit lower than the 8-12*C that was presented as a certainty not so long ago...

 

[Audax]

West? Do you mean East?

Gah ... yes, I meant East. Monday-itis strikes again!

 

[Papa Lazarou]

I notice everyone's favourite grumpy Uncle has been rather quiet now that even the BBC are showing pretty cold temps for next week (Uckfield day time max of 2*C for the 27th). That's a good bit lower than the 8-12*C that was presented as a certainty not so long ago...

To be fair, he didn't give a detailed view on NEXT week, he only forecast the temps for THIS week. He did make some general comments about there being no snow, and no cold though.

 

[Audax]

To be fair, he didn't give a detailed view on NEXT week, he only forecast the temps for THIS week. He did make some general comments about there being no snow, and no cold though.

True. But then, BBC's also got it down to 5*C for the 23rd and IIRC that was his key date where BBC were suggesting 8*C or higher. BBC forecast has been gradually trending colder as we've got closer to that date.

 

[Weststander]

I find the BBC tend to err on the milder side at range and tweak it as they get closer. Just to check, is that the Online BBC 5 day forecast or an actual forecast with a person etc?

The only reason I ask is that the automated 5 dayer has no 'human' input and just represents the raw data from 1 run from 1 model, which makes it prone to inaccuracies and swings.

Hi. The online version.

 

[Papa Lazarou]

True. But then, BBC's also got it down to 5*C for the 23rd and IIRC that was his key date where BBC were suggesting 8*C or higher. BBC forecast has been gradually trending colder as we've got closer to that date.

Oh I agree. I was just waiting to see what actual temps we get this week before commenting.

 

[Papa Lazarou]

Hi. The online version.

That makes sense. As [MENTION=33374]Audax[/MENTION] and I have mentioned, they can be very unreliable (at short range they're usually fine)