josh-weather
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Posts posted by josh-weather
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blizzard81 yes you're right probably was a bit harsh. Thanks!
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blizzard81 Said with confidence, but why?
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@TEITS An outlier compared to the ensemble members though - I thought the point of the control was to see if resolution was having an effect. If the op and control are the same then resolution isn't affecting the ensemble outcomes, which I'd take as reinforcing the outcome of the ensembles overall - which are mostly mild for that date. In other words the fact op and control match is an indication that the ensemble as a whole might be decently reliable. Please somebody explain where I'm getting this wrong, everything I learnt I learnt from this place
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Snow aside, I can't really see much difference between today and yesterday. Still going to be cold, not dramatically so but nothing much different to what has been showing for a while. Snow wise isn't it partly a matter of seeing what turns up anyway?
edit: Fair enough, the low did move south again - quite a shame for southern regions if that's what happens.
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29 minutes ago, Midlands Ice Age said:
I am afraid that we are now getting to the point that it is now the errors and assumptions in the software are causing the greater errors.
Until you get those sorted out you will just magnify the errors, and end up with even more chaos.
Spoken after 40 years in the software industry.
MIA
But model performance hasn't dropped... Has it?
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31 minutes ago, ICE COLD said:
What about the following weeks please ?
Here you go (Available here if you were wondering!)
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1 hour ago, Audaxian said:
Higher number better or worse? Just looking at that specific chart, you can see that 17th sticks out (all the models either right on the button or way off it), and then if you look at the days before the 17th vs the days after the 17th there's a noticeable shift from being mostly clustered in the 0.3 to 0.6 range, vs mostly clustered 0.5 to 0.7.
I'm assuming these appear with a bit of lag? How long would that be - a few days or are we talking week or longer? If it's a short enough lag, we could be using these charts to "estimate" how reliable the model runs we're seeing currently might be; eg if they've been trending "bad" pile on some extra salt?
If I'm reading it right, higher is more accurate. And it is showing the day 10 accuracy, so for example on the 17th, how accurate were the forecasts for the 27th compared to what a really happened on the 27th. There's a big dip at Christmas which is because there is less data available on Christmas day, meaning the forecasts made on that day have lower accuracy.
It is showing specifically accuracy of 500hpa anomaly.
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Latest from EC46. So it moved like the EPS did. Though I'm definitely not qualified to say what the implications are!
https://charts.ecmwf.int/permalinks/mean-zonal-wind-at-10-hpa-extended-range-forecast-64400
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10 minutes ago, January Snowstorm said:
Have we had even one decent ecm run in the last 2 weeks?? I'm far from convinced about all of this. Hope and potential yes, but it is far from guaranteed
The ECM runs out to 10 days, I thought we wouldn't see effects from the potential SSW until the very end of the run or afterwards, and certainly not at all a week or two ago?
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Has anything really changed that much since yesterday? You folks are the best but I swear this thread could be a case study in crowd dynamics
I'm waiting for the 46
https://charts.ecmwf.int/permalinks/mean-zonal-wind-at-10-hpa-extended-range-forecast-39219
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Just now, Kasim Iberian Heights Awan said:
In this case I think it was just the 12Z not the 18
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To be fair it doesn't have to go all the way across the continent to end the cold spell in the UK!
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RTE reporting more than 100,000 homes and businesses in Ireland without power due to the storm!
More than 100,000 properties without power due to storm
WWW.RTE.IE
More than 100,000 homes and businesses are without power this morning due to Storm Debi, an ESB spokesperson has said, as a Status Red wind warning remains in effect for...-
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17 minutes ago, WYorksWeather said:
It must be doing some sort of interpolation though - I thought GFS only has 3-hourly? I think nullschool also brings in other data. I've tried to research it though and it does seem a bit opaque exactly how it works.
Now that I'm not sure of! It does say "GFS / NCEP / US National Weather Service" when you're in the wind overlay to be fair, not just GFS. But I had always assumed the actual wind map (rather than the over animations it can overlay) was GFS. The source code is available so maybe it would be possible to see exactly what it does.
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20 minutes ago, James Maidstone said:
Doesn't nullschool just display the GFS model though (for wind anyway)? It won't update each hour, it will just show whichever hour you choose from the latest run it has, I think?
Edit: As others have said!
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It doesn't really matter though, its basically all one set of impacts. It makes more sense to call it one thing - the technicalities are less important than the consequences.
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Wow, that's really bad
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2 hours ago, northwestsnow said:
Euro heights are becoming almost a permanent fixture in winter.
Kiss goodbye to cold winters if this transpires..
It's hard to be optimistic but hope springs eternal !
To be honest with the speed at which things are changing, things that seem permanent might totally change any moment. The trend is gonna be for less cold overall but maybe more extremes including cold extremes, so you never know. My one positive (more like consolation prize!) from global warming!
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12 minutes ago, Djdazzle said:
The BBC forecasts are such a joke. Gone from 25C to 23C for Sunday. No way on Earth is Sunday cooler than Saturday when every parameter suggests the opposite.
GFS 00z Op and Ens both show cooler for your location on Sunday compared to Saturday. I've read BBC's provider primarily use ECM but who knows!
The 00z Op run is widely much cooler on Sunday. Just one run, etc etc. But the Ensemble mean is also lower. Let's see what the 06z says.
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11 hours ago, Metwatch said:
Why do I have the feeling you don't have access to the GDSM charts? I don't think many non meteorologists can access them to the best of my knowledge.
What is GDSM? I can't find any reference to it except for here
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35 minutes ago, matty40s said:
How pathetically bad the Metoffice radar now is...
That's the forecast, not the radar!
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3 minutes ago, Kentspur said:
But when the op and control are so tightly aligned I often think of them more as a trend finder given higher resolution. We live in hope
I guess it's probably more complicated than this (and I'm just going by what others have said here) but I thought Op and Control aligning was an indication of the validity of the ensemble run? I.e. that the result wasn't much affected by the different resolution. Which would make both the Op and Control outliers and if reality is slightly different to their (same) inputs we're more likely to end up closer to the ensemble mean?
Anyway no complaints here, we have lots of nice cold weather coming either way
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17 minutes ago, Notty said:It is odd that the model runs are published with impossible/unprecedented situations. I would have imagined that really silly modelling would be highlighted and reviewed by humans. It is a bit like poor payment systems that send ridiculously high payments out to people. Where is the common sense check?
There is a human check - professional forecasters do not just present a run as fact and will certainly not just take them at face value. The fact that us normies can also see them is nice transparency and a service to us all. It's really a great thing that we have access to so much raw output and can try and make our own forecasts from it - and if we do so, that necessarily has to include deciding what is or isn't realistic in the output.
Edit: and if someone in NOAA decided not to release a run on the basis of one low, what would the effect be on all the other forecasters internationally looking to use the model? They can't just pull a run on their own judgement. It is a model with international coverage and use.
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9 minutes ago, Liam Burge said:
I'm just as excited about this potential cold spell as much as the next person, however, isn't it always the real cold is day 10+?
Isn't this just a result of chaotic atmosphere Vs attempts at prediction? It can be seen with ensemble runs too, a widening envelope of possibilities into the future, because we can't really predict well out there.
Individual op runs can vary just the same, its just that we experience them one at a time and fixate on the very cold ones while binning the very warm ones.
The wildest of weather will always be more likely to show up in the distant reaches of FI, surely. Just because of the mechanics of how this whole thing works.
Meanwhile theres a nice more seasonal spell coming up, further cold in the ensembles and who knows we might get lucky.
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Model Output Discussion - Spring Has Sprung
in Forecast Model Discussion
Posted
GFS 06z and 00z both are warm outliers in the ensembles. The ensembles have quite a cluster of runs colder than average further north. Less so shown below for London but still the OP is way up at the top.