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Ben Sainsbury

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Posts posted by Ben Sainsbury

    Model output discussion - the beast arrives

    in Forecast Model Discussion

    Posted · Edited by Ben Sainsbury

    2 minutes ago, Nick L said:

    Those snow depth charts are completely inaccurate. No idea what algorithm they use but it's nonsense!

     

    4 minutes ago, parrotingfantasist said:

    They are complete nonsense at this range and often at any range. They aren't indicative of anything much and are almost always completely wrong. Take this years PM air streams for an example of why these are nothing but eye candy.

    Agreed, merely eye candy as all precipitation is accounted for in its accumulation. 

    As inaccurate as these snow depth charts normally are, my intention was just a case of showing how well the ECM has delivered (snow depth wise) compared to other models/previous runs.

     

    South West and Central Southern England Regional Weather Discussion 22/02/2018 Onwards

    in Regional

    Posted

    As the large potential snow event has now come into range on the NetwX MR model, I was intrigued to have a look. Can safely say I'm in shock and as unlikely and unpredictable it is to forecast as far ahead as Thursday.

    We're looking in excess of 18 hours of snow and as the rain to snow ratio is approximately 1:6, we're looking at 15cm+, likely much more.

    Just for fun tho and taking with a massive pinch of salt but interesting nevertheless given no marginality.

    • Like 1

    Model output discussion - Post SSW - Will it turn cold?

    in Forecast Model Discussion

    Posted · Edited by Ben Sainsbury

    11 minutes ago, Danielvn said:

    People are ignoring the elephant in the room because it suits their agenda. Only a fool would ignore the ECM aid it’s showing one thing and the others are showing another thing, yet the ECM is unwavering in its view of what the weather is going to do. But rampers gonna ramp I guess.

    I completely agree with you, without the ECM I have little confidence that the other big models are likely to get the pattern nailed on. 

    At the beginning of the SSW event, many of the models were playing with the idea of high moving NE across the UK, but as a whole the models generally flipped between cold & mild setup. I only feel once the ECM caught onto the pattern, that many of the other models were beginning to firm up on the pattern we are looking at. Given its such a complex setup we are looking at, the verification statistics and the exceptional vertical resolution of the ECM that it would be stupid to ignore personally.

    The ECM has the largest capability of correctly modelling this pattern.

    But as many of you have said, almost all the other big models have consistency forecast a very cold pattern for several days now with good cross agreement, so who knows. 

    Model output discussion - Post SSW - Will it turn cold?

    in Forecast Model Discussion

    Posted · Edited by Ben Sainsbury

    16 minutes ago, Penicuikblizzard said:

    Still plenty time for a spanner in the works to appear,,this event is still a week away a long time in terms of weather 

    This is where I disagree, for the deep cold we are most certainly looking a week away.

    But for the general pattern we are looking at 72-96 hours at most; we are very close to nailing this upcoming spell. (Although the GFS seems to bring the cold in 12 hours earlier compared to the ECM)

    GFS.png ECMWF.gif

    • Like 4

    Model output discussion - Post SSW - Will it turn cold?

    in Forecast Model Discussion

    Posted · Edited by Ben Sainsbury

    3 minutes ago, karlos1983 said:

    My understanding is the more levels the more likely it is to be accurate. Unless of course you have a historical SSW unfolding, at which point it could have 300 and we’d still be none the wiser lol

     

    5 minutes ago, titchjuicy said:

    May I please ask what the levels of vertical resolution refer to?

     

    Only have a basic understanding too, but the ECM which have double the vertical levels of GFS has a better grasp at predicting the track and development of weather systems than the GFS. 

    I think? :cc_confused:

    • Like 1

    Model output discussion - Post SSW - Will it turn cold?

    in Forecast Model Discussion

    Posted · Edited by Ben Sainsbury

    Interesting, done a little research...

    For comparison with JMA's 100 levels of vertical resolution.

    The ECM uses 137 vertical levels, whereas the GFS uses 64 levels. 

    Whether there are any relation to how the JMA & ECM have a similar pattern at the moment unsure. 

    EDIT: ARPEGE runs with 105 vertical levels.

    Therefore the 3 models all of which following a blocked pattern all have the largest amount of vertical levels compared to the UKMO and GFS which have less.

    • Like 6
    • Thanks 2

    Model output discussion - Post SSW - Will it turn cold?

    in Forecast Model Discussion

    Posted · Edited by Ben Sainsbury

    I have been thinking and reading about each of the models especially the GFS and ECM.

    I have seen many mention on here that the ECM has been particularly poor this winter, whether this be the case or not, this has no impact on the current projections from the ECM. If I'm going to be quite honestly I think this is merely a case of all the models performing exceptionally poor given the SSW. Given a record breaking SSW how can any of us expect the models to handle this well when this is data they haven't received before? (If you know what I mean)

    For the cold scenario that we all hope for the ICON has been excellent with consistency but I have a lack of knowledge to comment on it's general consistency, however now the ECM is in line with the ICON (and should take the lead in regards to the upcoming pattern) I next expect the GFS to move in line. After some research it seems that the GFS whilst using the ECM initialisation data performed much better than using its own "initialisation" data, you may wonder why this is relevant?

    Well I expect as I mentioned already for the GFS to be the next model to now move in line with the ECM as it begins to latch on to the trends that the ECM have picked up on.

    Whether this is relevant or not, it's my own personal opinion (& very much an amateur), we'll see what happens! For the time being lets enjoy some very controversial model outputs!

    • Like 1

    Model output discussion - Post SSW - Will it turn cold?

    in Forecast Model Discussion

    Posted · Edited by Ben Sainsbury

    27 minutes ago, Southender said:

    Question is can the UKMO be wrong at day 4/5? Yes, of course it can. But me personally I would rather a UK model on board with cold than not, over an American/French/Ugandan/*insert any random country you wish model. If we see a UKMO climb down this evening, then we can perhaps start to question whether it has day 4/5 nailed over the rest. My personal feeling is the cold is coming in the next 7-10 days, it’s just how long will it last and how cold will it be are the questions. 

    I completely understand where you are coming from, but I still struggle to believe that the pattern will completely flip being just 96 hours out. We can of course see small changes but I just don't see its latest run being wrong given its current consistency.

    South West and Central Southern England Regional Weather Discussion 19/01/2018 Onwards

    in Regional

    Posted · Edited by Ben Sainsbury

    It's interesting with this upcoming event Thursday night into Friday. The current GFS shows rain turning to snow readily across the SE as the colder 850hpa temps move in from behind. There has been an increasing tendency over the last few days for our weather pattern to correct east. Not only that but from my own experience I don't expect the front to move so quicker into the block of cold air sat over us, have a strange feeling the front is likely to slow down or to be pushed further as it moves eastwards hopefully allowing the cold air to undercut the front. Obviously the NetWx SR currently shows just a band of rain for Friday but if the front doesn't move through so swiftly, who knows what will happen.

    • Like 1

    South West and Central Southern England Regional Weather Discussion 19/01/2018 Onwards

    in Regional

    Posted · Edited by Ben Sainsbury

    10 minutes ago, karlos1983 said:

    Predicted and actual

    5EE813ED-5A02-4861-97F8-A31F3F183008.thumb.png.0a50811c0c265800f7042a669cdedce2.pngF52E3FB4-A59F-430C-8A92-5E79ECAFD5EE.thumb.png.0d3b8e2039cab87f263103b88e70c105.png

    certainly seems to have a bit more poke that predicted ATM.

    Aye don't be so sure that screenshot of the current radar is a good 20 mins in front of the predicted rainfall! For all we know that rain band could fade that much within 20 minutes! :nonono:

    From what I've seen according the Netweather SR model that the band of precipitation seems to reinvigorate as it passes through the Irish Sea.

    Model output discussion - proper cold spell inbound?

    in Forecast Model Discussion

    Posted

    1 minute ago, Daniel Smith said:

    The South-East contingent is busy radar watching and running to the window every 30 seconds. 

    That and the fact the 12z GFS has barely changed at all from it's previous run, there's not a whole lot to comment on. 

    Quite amazed how few changes there are up +180. Here we begin to see a much deeper low develop near Newfoundland bringing greater WAA into Greenland which could benefit us later on; in the realms of FI tho.

    • Like 1

    Model output discussion - proper cold spell inbound?

    in Forecast Model Discussion

    Posted · Edited by Ben Sainsbury

    12 minutes ago, MattStoke said:

    On the 12z Thursday's front looks a bit further east, with the cold air ahead of it further east. However, the air behind the front is colder (-8 uppers more widespread). 

    Blimey. Where is everyone?!

    Some 148 members viewing the chat right now!

    On topic you're right, even though the timing of the front is a good 6 hours in front of the 0z, the warmer uppers seemed to be more efficiently mixed out bringing quite heavy snow to central areas. If we can see the warm uppers mix out a little earlier we could end with a widespread event.

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