Evo
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Posts posted by Evo
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I think a pattern is emerging from this - we have probably all thought through empirical evidence that each model would cope with certain set-ups well, whilst struggling with others. I was slightly sceptical of this view but your analyses seem to be showing that this is the case.
The JMA has handled certain recent setups well but it hasn't got a clue with others. This even seems to apply to the GFS and the UKMO, though obviously to a lesser degree. The leader does seem to be the ECM, which given that statistically is the most accurate global model, makes sense. More often than the others, it has something which, whilst obviously not dead on, is good enough to make a pretty decent mid range forecast.
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After a glorious start to the day it clouded over just in time for the eclipse! However in the last 20 minutes it thinned enough for two brief glimpses, luckily. Interestingly, my horse has been going ballistic out there for the duration of the eclipse. Coincidence?
Perhaps the horse was annoyed that you didn't give him some eclipse glasses so he could watch?
Didn't get to see anything here - forgot to look but it was cloudy anyway.
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7.7 using my super secret and ultra accurate method of prediction.
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Thanks john, I think a little knowlege can be a dangerous thing!
I've found a formula to convert from QFE to QFF, do I need to convert QNH to QFE, then QFE to QFF or is there an easier way?
The formula I found is QFF = QFE / Exp (- ((g*Z)/(R*Tave)))
Where:
g = the gravitational constant, 9.80617 m/s2
Z = the airfield altitude in metres
R = the dry air gas constant, 287.04 m2/s2
Tave = the average temperature between sea level and the station altitude in degrees Kelvin. <--- I can see this being a problem.
If I've got this straight in my head, QNH is like QFF but QNH assumes the ISA standard atmosphere, so the above formula would convert QFE to QNH if the temperature used was adjusted from the observed temperature using the ISA tropospheric lapse rate of 0.0065 degrees K per metre. To find the QFF, I would need to know the true lapse rate to find Tave.
Am I on the right track or have I confused myself and made it more complicated than it needs to be? Would it instead be best to just allow a few hectopascals difference when analysing?
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Hi John
The data source I'm using for the GFS gives kph, so the METAR is converted from knots to kph, so they match. I'd rather they were both in knots but they way it's just done now is the easiest! Also, I'll have to check about the pressure, I think you're probaby right - the airfield METAR will be giving the QNH and the GFS will be predicting the QFE.
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Attached are some preliminary images covering the GFS from T+24 to T+96 at 18z for a couple of locations. Interesting to note that the GFS was pretty accurate, with the slightly odd exception of the dew point which was totally wrong really. In a couple of weeks, there will hopefully be something a bit better and at longer range to post up.
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Ultra light snow grain shower this morning. The very definition of the term "snizzle".
(Bournemouth)
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I definitely didn't receive anything - not to worry!
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I'm not sure if this is a problem or not. I decided to archive my PMs rather than sort through what needed to be kept (if anything http://nwstatic.co.uk/forum/public/style_emoticons/<#EMO_DIR#>/laugh.gif ). Having gone through the procedure I haven't received the email. The messages have been auto-deleted OK, they just weren't sent to me (or so it would seem). I don't think there's anything imporant in there - just wondered if it's a known problem?
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Evo, what language did you use to parse the meteostar document? Would you be willing to share the source code for it?
VB6.
If you give me a mo, I'll post the cost. Don't expect it to be pretty :blush:
Code PMd.
Sorry for cluttering up your thread John!
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Hi Mark
It's still very much in the alpha stage at the moment. The daemon is pretty much totally functional, but still a bit shakey and tends to fall over now and again. I'm fixing it up as I go. Within a couple of weeks I should have sufficient data for the output to make sense.
Anyway, I am getting the point data from here:
http://wxweb.meteostar.com/sample/
If you enter an ICAO airfield code, it will give you the point data.
I'm downloading the METARS from lfv.se because the weather.noaa.gov ones are a bit slow to update. The daemon downloads the pages at set times and then parses them to extract the data.
In terms of raw data, we have 16 rows (4 rows per ICAO site) of METAR data a day and up to* 96 rows (6 rows per ICAO site per run) of GFS data a day - it's not that much data to be honest. It's currently going into an access db but I also have MySQL and SQL Servers available to me to use.
* The meteostar site seems to update erratically, sometimes missing runs.
Once I have a proper dataset built up, I'll send you a copy and you can do your statistical magic on it. If you're interested in the code then at some point I can send this over as well. It needs a lot of tidying up first though.
One last thought - ideally the data would come from the GRIB output but this is just too complicated for me to attempt at the moment. Not only that, the GRIB files aren't exactly small!
hi Evothat looks very interesting. I'm no computer expert, if OON reads this he will probably die laughing - oh I don't know) but the idea like I say is interesting.
Just one point, in no time at all you will have a huge amount of data, so perhaps best to concentrate on 3 or 4 at the most. How to pick them, not really sure.
Puts in advert for self!
I'm now doing T+168 with Doncaster, or rather my forecast based on T+168, as check.
Any chance of sending me the programme, assuming its simply a matter of click this then that and hey presto its there??!!!
As I say, along with TWS we may actually start getting some proper data to use to get real solid comparisons.
John
just seen your edit re the 3 airports. I would keep it at that for the time being.
John
Hi John
To be honest the program wouldn't do a lot for you, it needs to be running on a server 24x7 and have permanent internet access. You are quite welcome to share the data it creates though, in whatever format is best for you. Your input is obviously valued so please feel free to let me know what you think!
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Hm try again, the first post got killed by a crashing Internet Explorer
Hi John,
I am currently working on a program that will download point data from the GFS runs for a number of UK locations automatically at regular intervals at distances from T24 through to T168. It will also download the relevant METAR for the times of the predictions and present the result in a self-updating image like this:
[ignore the actual figures here, it's mostly dummy data]
Once a sufficient data set has built up it should be possible to do some calculations to establish how accurate the GFS is at various ranges and for various locations. Quite exactly what, how, why and when I'm not sure but it should be something else interesting to throw into the pot.
Edit: P.S. The current locations are Bournemouth, Heathrow, Manchester and Glasgow. These will probably change at some point to give a good geographic spread.
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Light snow in Bournemouth now, dusting on cars and roofs overnight - not on ground.
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No problem chaps, glad to help
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In view of the WZ problems tonight, here are some alternate pages which use different WZ links. These are working OK.
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Evo, i have used the correct spell, and its definition is a split Jet Stream.
i.e. at least two Jet Streams
Please could you provide a link showing this definition?
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Just a point that's been niggling me JS, I've never heard of the the term beaurificated. Do you mean bifurcated?
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Hi TWS
I've done the other times and added the other oddball models in - it's obviously up to you which ones you use!
Here are the links:
Only Nogaps, GFS, JMA & GEM have 850s on Wetterzentrale, with the GEM 850s only going out to T+120.
If you can, save the above pages to your hard drive by using the File -> Save As menu item in your browser, as they may not stay on the above links forever. If you save them to your desktop, you'll have ready made shortcuts.
Hope this helps!
Oh and one last thing, try to check the model shown is correct (at the bottom of the image) as once or twice the radio button on the right has said one thing but the Nogaps has been displayed! I think this only happens when using the refresh button. The image goes back to Nogaps but the radio button on the right will stay on whatever it was before you press refresh.
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TWS
I don't know if this will be of any use to you. I fixed it up from an old semi-broken page I found on the Internet.
This is for T+96 but if it's useful I can do other timebases too. I think they will all line up timewise with 12z data just before the 18z GFS comes out?
Sometimes the fader breaks. Just hit the refresh button to fix. Best viewed at 1024x768 screen resolution or greater.
Let me know...
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Cheers Paul. I thought the satellite might be tricky as most of the images are skewed to some extent, and then there's the scaling... What I was thinking of for the compass was to be able to click and drag to make a line and get a distance and bearing reading. What you have in planning sounds better anyway.
Thanks again
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I'm guessing this is a known issue but I'll prattle away anyway
On the radar, there seems to be issues with the caching of the images. If you view the radar one day and then view it again the next day, you'll sometimes get the current image and you'll sometimes get the cached image from the day before. If you press the refresh button the latest image will show but then when the page auto-refreshes you get the old cached image again. Also if you try to animate you'll get the cached image, even if you've used the refresh button.
Can you send an "content-expires" tag with the page or do something to stop this?
P.S. This has happened on several machines, but they are all XP with IE6 so it could be a browser thing...
P.P.S. Features that would be nice for the next version (IMO)
* Adjustable animation speed, ping-pong option
* Satellite overlay option
* A drag-able tape measure and compass rose so you can measure rate and direction of a feature (I know what I mean but does this make sense?!?)
There are other ideas I've thought of in the past but my mind has gone blank now I've tried to write them down
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6.2 for me. An up and down month I reckon with a bit of everything.
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15 minute very heavy snow shower. Eventually began to settle but thawed within 5 minutes of the sun coming out again.
(Bournemouth Seaside)
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Brief heavy snow shower on Bournemouth coast. Lasted about 10 minutes, no settling.
Vantage Pro 2 Question
in Spring Weather Discussion
Posted
If you look on the cable sheath, it will often have the cable type printed there somewhere. I've no idea what cable you have but you've mentioned telephone cable so I would suggest external grade Cat 5e becuase normal cable will rust and rot eventually, even breakdown under UV from the sun. I bought some to do some external telephone wiring on a 300m reel for about £100, you should be able to find shorter lengths on the Internet. Something like this: http://www.betterbox.co.uk/acatalog/Produc..._Grade_441.html.
I can't see that trying some el-cheapo telephone cable (which is actually Cat 3 cable) will do any harm. The worst thing that will happen is that you have to replace it again in a couple of months.