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Author Topic: First Storm of the Season on it's way!  (Read 2012 times)
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Tugmistress
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« Reply #15 on: September 08, 2009, 06:12:00 PM »

highest gust up here so far (if it's not already gone past the worst) was 54.1mph at 5.29pm
baro been rising for a few hours too now.
OH has just driven through elgin and said it was very windy, he's hoping kessock bridge is open again (to high sided) when he leaves inverness to come up here tonight with the lorry, and i'm hoping by the time he gets here the worst is over as i don't fancy unloading a curtain sider in this!
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munrobaggins
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« Reply #16 on: September 08, 2009, 07:03:34 PM »

....OH has just driven through elgin and said it was very windy,.....
OH must have come right by my house then (I'm right by the A96 opposite Dr Grays Hospital)....and it is still quite windy even now..I hope the Kessock is open for the OH...I have noticed Scrabster, Skye marble and Stornoway trucks going past a lot over recent days, weeks, months etc.. Smiley Wink
« Last Edit: September 08, 2009, 07:08:42 PM by munrobaggins » Logged

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« Reply #17 on: September 08, 2009, 07:07:00 PM »

Orkney & Shetland still have a bit to go I think, but for the rest of us the Low is well to the north now and the pressure here is rising nicely.

Not bad work on the map there Sean, got it about right I think.  Grin
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weathermaster
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« Reply #18 on: September 08, 2009, 10:46:14 PM »

Thanks  Grin

Top gust here was 70mph at 12pm today.
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Tugmistress
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« Reply #19 on: September 09, 2009, 10:16:01 AM »

....OH has just driven through elgin and said it was very windy,.....
OH must have come right by my house then (I'm right by the A96 opposite Dr Grays Hospital)....and it is still quite windy even now..I hope the Kessock is open for the OH...I have noticed Scrabster, Skye marble and Stornoway trucks going past a lot over recent days, weeks, months etc.. Smiley Wink

kessock bridge was open Smiley he got here about 10.45 last night Smiley he'll be driving past again heading to aberdeen this afternoon (Northwards lorry). i'll be travelling with him next week Smiley  - oh and just for some light humour, when we got engaged i got the mickey for a while his name is Michael Fisher (on the local message board i'm the weather girl and someone shortened his surname and asked if it was a mickey take lol)
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munrobaggins
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« Reply #20 on: September 09, 2009, 10:18:51 AM »

Now that is some gust....was it real I ask?
« Last Edit: September 09, 2009, 10:20:25 AM by munrobaggins » Logged

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« Reply #21 on: September 09, 2009, 10:25:56 AM »

....he'll be driving past again heading to aberdeen this afternoon (Northwards lorry). i'll be travelling with him next week Smiley  - oh and just for some light humour, when we got engaged i got the mickey for a while his name is Michael Fisher (on the local message board i'm the weather girl and someone shortened his surname and asked if it was a mickey take lol)
See if you can spot the anemonmeters...one on the chimney and one on the topped leylandi tree next to the road...and as for M Fish..No wonder folk were thinking you were taking the mickey...what a thing he'll always be remembered for...I was passing thru' Heathrow (and then Cheltenham bound) the day after the "Storm"...what a mess there was down there..
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« Reply #22 on: September 09, 2009, 11:07:14 AM »

Now that is some gust....was it real I ask?

I would question that one, unless you're in a glen where the wind funnels past or you're on top of Munro.  Wink

I lived in Southampton in 1987 and knew anything about the storm until I was driving to work the following morning. I looked around at the fallen trees and wondered what caused it? Must have slept right through and not heard a thing!!  Cheesy
I did spend that evening helping out at the Lifeboat station with sunken fishing boats etc in the Hamble River.

Poor old Michael Fish, they keep on about what he said but he wasn't talking about the Low, he was referring to the remains of a hurricane that was active on the Eastern Seaboard of the U.S during the same week. It's only the media that keep dragging it up as a 'gaff'.  Roll Eyes
Bill Giles was actually the duty forecaster that night. 
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Budgie
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« Reply #23 on: September 09, 2009, 11:43:01 AM »

Just checked my visitor figures for yesterday, normally I get an average of 140 to 160 unique visitors per day with 250 to 320 page views.
Yesterday saw 648 unique visitors and 1409 page views!!  Grin
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skyewright
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« Reply #24 on: September 09, 2009, 02:18:35 PM »

Now that is some gust....was it real I ask?
If you look again you'll find no trace of that...

Something very odd seems to have been going on with the Inspeed/Hobby Boards anemometer ("wind8") between 0320 and 0610.

I stripped all the "wind8" data out of the meteohub database between 0315 and 0615, restored the 0048 backup of WD, then reran this morning from the (edited) logged data, with wind data from the 'old' WMR200 filling the gap. All that was still going on when you grabbed your screen shot.

I now need to do some data analysis to see if I can find a way to "logically" spot and exclude such a thing. Sad

I have 1 second resolution "debug" data from the  Inspeed/Hobby Boards. It doesn't appear to be quite what I had before installing the 'low pass' filter as there isn't a single "off the scale" reading, just a lot of "unreasonably high" ones. There was no rain at the time. My HB lightning detector didn't spot anything (but it's still in the house). There aren't dramatic fluctuations in the 'click' count from second to second. If it was electrical is was low frequency (or intermittent) enough to only add 20-30 'clicks' a second to the count and that would be very hard to filter out without loosing real data. And of course it all happened while no one was watching!

It's a case of being "obviously wrong" to the human eye, but it may be very awkward to define logically (but I'll try).

All very strange.  Sad
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« Reply #25 on: September 09, 2009, 02:23:36 PM »

I would question that one, unless you're in a glen where the wind funnels past or you're on top of Munro.  Wink
Me too. Gone now. Investigating...

I believe that it was just a temporary anomaly and yesterday's data was valid. I also still believe a 77mph gust squall one Saturday evening in late August that isn't reported on the website - I witnessed that one and it was a wild few minutes!
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« Reply #26 on: September 09, 2009, 04:10:16 PM »

It's a case of being "obviously wrong" to the human eye, but it may be very awkward to define logically (but I'll try).
All very strange.  Sad
The funny thing is that it was all brought to my attention by a pal of mine over here....and he was wondering if it was real?  All very strange as you have said, but interesting none the less..
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« Reply #27 on: September 09, 2009, 05:39:54 PM »

All very strange as you have said, but interesting none the less..
As I have the OS gear there as a fallback, and have code set up so that fallback is automatic (i.e. if wind8 doesn't appear in a given minute, then data from wind1, the WMR200, is automatically fed to WD instead) I hope to come up with a test (probably something erring on conservative) for "better ignore this one". However given how gusty and strong wind can really be here that's not necessarily going to be easy to define!

To some extent it's a matter of deciding what is the maximum "reasonable" acceleration, then combining that with a few other things. I've not come up with a formula yet but I have a ton of those stuff to do too (and it might be that I'd be better trying to refine the 'hardware filter" anyway). Oh, well, must remember 1 Tim 6:8 and keep smiling.  Smiley Worse things happen at sea (and many other places!)...
« Last Edit: September 09, 2009, 05:42:20 PM by skyewright » Logged

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David
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« Reply #28 on: September 10, 2009, 10:14:34 AM »

...and it might be that I'd be better trying to refine the 'hardware filter" anyway
The more I look at it the more it looks as though hardware (perhaps plus some extra spike logic) is the best angle of attack. Some sort of electrical interference at a level that hadn't cropped up so obviously before seems the almost certain cause.

Taking a close look at the data the 105 mph gust could have been spotted logically quite easily (a 50mph acceleration between one second and the next!), but just before that there was another well over 90mph that was much more subtle, with each step in the chain quite reasonable in itself.

I'm assuming that the interference is coming in short bursts of highish frequency rather than being sustained low frequency (as low as 20-30 Hz).

IIRC the current low pass filter clips at about 160 Hz in theory (well beyond any real weather), but that assumes no extra resistance or (probably more important) capacitance in the circuit. Without a scope (and ideally a signal generator) it's hard to be certain exactly what it is clipping at and (aside from reporting invalid data) the last thing I want to have is a system that starts clipping real gusts!


If the weekend is dry (as looks possible) I may take wind8 out of the WD equation, then try adjusting the filter so that the theoretical clip is within what is actually happening and see how theory compares to reality. Then I can maybe adjust the filter to values that are tighter.

So what chance a flat calm, eh?  Wink
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David
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« Reply #29 on: September 11, 2009, 09:42:02 PM »

If the weekend is dry (as looks possible)...adjust the filter to values that are tighter.
An opportunity appeared late afternoon today. I swapped the resistor for a much bigger one bringing the theoretical 'clip' down to about 9mph. It was gusting to around 15mph at the time, but with the changed filter the anemometer wouldn't register above 11mph. That seemed reasonably close to theory to me.

The anemometer is now back in service running with a resistor & capacitor combination that clips at slightly less than half the previous frequency, which hopefully will be enough to avoid future problems.

There is probably scope for further reduction but that would involve either series or parallel resistors (there's just one resistor and one capacitor at present) so probably best left for a soldered version rather than the connector block arrangement that is currently in use!
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