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#1459008 - 25/03/2018 19:30 Re: NSW/ACT day to day weather [Re: Grant]
Wave Rider Offline
Meteorological Motor Mouth

Registered: 27/01/2014
Posts: 7003
Little bit of moderate rain here and that I was all. I was out body boarding in it and there was no lightning that I saw. But some interesting cloud structure and a fair bit of wind happened.
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#1459016 - 25/03/2018 19:45 Re: NSW/ACT day to day weather [Re: Steve777]
Homer Offline
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Registered: 16/06/2007
Posts: 6000
Loc: Dural
Originally Posted By: Steve777
Maxima and minima are for 24 hour periods. 9:00AM is as good a reset time as any. Even in mid winter (or at the end of Daylight saving), it's nearly two hours after sunrise, about the usual time for the minimum, while it's also well away from the normal time of maximum. Places at high latitudes where sunrise might be 9:00 or later in Winter might have a problem with it.

There is the odd anomaly, for example, 'bonus additions' to maxima on some days. Also, if the minimum does occur around 9:00. I remember an unusually cool January morning a couple of years ago when it was bucketing down at 9:00AM and 14 point something. That resulted in two very low January minima, even though there was 'really' only one cold morning, with temps bouncing back towards normal later in the day and the following day.

Any other reset time would cause these sorts of anomalies. Getting away from 24 hour periods would just be too messy.

True highs and true lows will never be missed, but sometimes they might be recorded against the 'wrong' day.


You are missing my point.
Why can't the AWS's work to the 9.00 am to 9.00 am min and max time frame?

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#1459018 - 25/03/2018 19:50 Re: NSW/ACT day to day weather [Re: Grant]
EddyG Offline
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Registered: 19/12/2008
Posts: 5085
Loc: Port Stephens NSW
Homer, I would say someone is ball tampering!! Ooops I mean temp reading tampering.

I know what you mean.
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#1459019 - 25/03/2018 19:56 Re: NSW/ACT day to day weather [Re: Grant]
kizz Offline
Weatherzone Addict

Registered: 11/02/2002
Posts: 2044
Loc: Beacon Hill, Sydney 152m asl
That storm was about as severe as a sparrow's fart here. Even our hyper thunder-phobic cat stayed put at the back patio screen door.

Funny to see the old 9am reset bubble up again. There is a historic reason to keep the old 9am reset for consistency's sake as has been mentioned. But I agree with Homer (unbelievable, I know). When the BoM's obs pages use different time criteria for min and max it does get a bit messy. Rainfall accumulation sticks to 9am but the temperature ... confused

What really annoys me is when I go to check the rainfall after nine in the morning during a big rain event!

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#1459020 - 25/03/2018 20:05 Re: NSW/ACT day to day weather [Re: Grant]
Steve777 Offline
Weatherzone Addict

Registered: 20/10/2011
Posts: 4441
Loc: Artarmon (Sydney North Shore)
Originally Posted By: Homer
Why can't the AWS's work to the 9.00 am to 9.00 am min and max time frame?

No argument from me. For some reason,on the BOM site, resets seem to occur at 6:00PM (minimum) and 6:00AM (maxima). Doesn't make sense.

One thing about the 9:00AM reset, which would happen with any reset time, is that you occasionally 'lose' records like low maximum and high minimum, which has been the subject of the odd complaint by some posters. Also very heavy rainfall split either side of 9:00. But that's inevitable with any reset time. You won't lose high max and low min.

EDIT: Severe Thunderstorm Warning cancelled.
EDIT2: There was a bit of wind, with sites around Sydney reporting gusts in the 50s kmh. Sydney Harbour and Mt Boyce, at 67kmh, plus Holsworthy at 74, were the biggest gusts.


Edited by Steve777 (25/03/2018 20:14)
Edit Reason: EDIT2.

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#1459023 - 25/03/2018 20:09 Re: NSW/ACT day to day weather [Re: kizz]
Homer Offline
Meteorological Motor Mouth

Registered: 16/06/2007
Posts: 6000
Loc: Dural
Originally Posted By: kizz

Funny to see the old 9am reset bubble up again. There is a historic reason to keep the old 9am reset for consistency's sake as has been mentioned. But I agree with Homer (unbelievable, I know). When the BoM's obs pages use different time criteria for min and max it does get a bit messy. Rainfall accumulation sticks to 9am but the temperature ... confused

What really annoys me is when I go to check the rainfall after nine in the morning during a big rain event!


Exactly my point. And I'm not being difficult here. I just don't understand why other figures use the 9 am to 9 am cut off, yet the mins don't?
It's quite confusing.

I will say it again...... todays officially recorded mins will be less than what the AWS's are showing for todays figures .........since 9 am.
I'm just asking why the AWS's do this?

** I've just checked the AWS site and the figures have now changed.

http://www.bom.gov.au/nsw/observations/nswall.shtml

Why?

The reasons given before are now implausible.

I'm only asking this to try and understand how they work.


Edited by Homer (25/03/2018 20:09)

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#1459026 - 25/03/2018 20:14 Re: NSW/ACT day to day weather [Re: Grant]
Knot Offline
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Registered: 01/05/2014
Posts: 2560
Loc: Toronto N.S.W
You'll do your head in Homer trying to divine the reasoning of the Byzantine Office of Meteorology he he
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#1459028 - 25/03/2018 20:18 Re: NSW/ACT day to day weather [Re: Homer]
EddyG Offline
Meteorological Motor Mouth

Registered: 19/12/2008
Posts: 5085
Loc: Port Stephens NSW
Originally Posted By: Homer


** I've just checked the AWS site and the figures have now changed.

http://www.bom.gov.au/nsw/observations/nswall.shtml



Max temp is still before 9am?
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#1459031 - 25/03/2018 20:23 Re: NSW/ACT day to day weather [Re: Knot]
Homer Offline
Meteorological Motor Mouth

Registered: 16/06/2007
Posts: 6000
Loc: Dural
Originally Posted By: Knot
You'll do your head in Homer trying to divine the reasoning of the Byzantine Office of Meteorology he he


That's what I'm trying to work out Knotty!!!
None of the explanations above have as yet, however sincere, provided an answer!!
I'm not sure anyone knows.
Why would the mins update this evening?
Nothing to do with the 9 am to 9 am excuse I've been given.

In saying that, I back up my claim earlier that I'd seen updates outside of that time frame for mins. BOM have now proven it.

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#1459043 - 25/03/2018 20:59 Re: NSW/ACT day to day weather [Re: Grant]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 7616
Loc: Adelaide Hills
Originally Posted By: Homer
Why can't the AWS's work to the 9.00 am to 9.00 am min and max time frame?

If I'm understanding accurately, maximum and minimum temperatures can be measured during alternative time periods to 9 am to 9 am, i.e. maximum temperatures from 6 am to 9 pm and minimum temperatures from 6 pm to 9 am (source).

While there no definite reason given through the above link, I suspect it is due to the temperature-curve of how heat is absorbed by the surface and then atmosphere, over the course of 24 hours. It can take, under non-dusty, clear-sky conditions, much longer for the air to heat up in the morning than for it to cool down towards dusk. If this curve was measured, it would look like a skewed parabolic curve -- like throwing a ball into the air, where the path of the ball is the temperature curve. For this reason, there are times during the day/night when it is highly unlikely the maximum or minimum temperatures will be reached. They also come before each other, so if a minimum was higher than a maximum in the same time period, that would be unacceptable from a statistical point of view, therefore one would have to ensure that does not happen, even if does not represent the reality of the unaltered diurnal cycle.

My view, however I hope this is helpful, and relevant smile .


Edited by Seira (25/03/2018 21:00)

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#1459045 - 25/03/2018 21:19 Re: NSW/ACT day to day weather [Re: Grant]
Wave Rider Offline
Meteorological Motor Mouth

Registered: 27/01/2014
Posts: 7003
Surely Dr Trewin would know?
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#1459054 - 25/03/2018 22:00 Re: NSW/ACT day to day weather [Re: Grant]
Steve777 Offline
Weatherzone Addict

Registered: 20/10/2011
Posts: 4441
Loc: Artarmon (Sydney North Shore)
As so often happens, the storms reignited out to sea. I can see distant lightning to the East, but it's a long way away.

EDIT: There are more shower cells about - the Central Coast, Blue Mountains and Illawarra. No lightning though.


Edited by Steve777 (25/03/2018 22:02)

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#1459067 - 25/03/2018 23:49 Re: NSW/ACT day to day weather [Re: Grant]
Stormy3 Offline
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Registered: 12/06/2013
Posts: 1783
Loc: Ellalong,10kms SW of Cessnock ...
A long train of showers,some might be thundery to my west,they are moving towards my area, see what happens about mid-night or a bit after.
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#1459070 - 26/03/2018 00:26 Re: NSW/ACT day to day weather [Re: Stormy3]
rain gauge Offline
Weatherzone Addict

Registered: 16/02/2006
Posts: 4534
Loc: Gorokan NSW 4klm West of the ...
Originally Posted By: Stormy3
A long train of showers,some might be thundery to my west,they are moving towards my area, see what happens about mid-night or a bit after.
I hope you get something Stormy. Your area has been deprived.
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#1459071 - 26/03/2018 01:34 Re: NSW/ACT day to day weather [Re: Grant]
Stormy3 Offline
Weatherzone Addict

Registered: 12/06/2013
Posts: 1783
Loc: Ellalong,10kms SW of Cessnock ...
rain gauge,Nothing up to 1.30am.There looks like something lining us up from the west though.just a light shower earlier



Edited by Stormy3 (26/03/2018 01:35)
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#1459072 - 26/03/2018 02:37 Re: NSW/ACT day to day weather [Re: Grant]
Knot Offline
Weatherzone Addict

Registered: 01/05/2014
Posts: 2560
Loc: Toronto N.S.W
This night warmth is not very pleasant. No sky juice. Maybe later.
Keep diggin Homer. Keep em honest
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#1459073 - 26/03/2018 02:56 Re: NSW/ACT day to day weather [Re: Grant]
Knot Offline
Weatherzone Addict

Registered: 01/05/2014
Posts: 2560
Loc: Toronto N.S.W
Nobbys has recorded only 1 below average min so far this March.
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#1459075 - 26/03/2018 05:43 Re: NSW/ACT day to day weather [Re: Grant]
Quagmelson Offline
Weather Freak

Registered: 15/11/2001
Posts: 904
Loc: Glenorie NSW
Had a storm with heavy downpour around 1am then a mod/heavy rain band 3am to 430am just cleared up north now. Up into "bushranger" territory, looks like Lefty and Poncho should get 5-10mm hopefully

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#1459077 - 26/03/2018 05:52 Re: NSW/ACT day to day weather [Re: Grant]
DerekHV Offline
Weatherzone Addict

Registered: 12/02/2010
Posts: 1202
Loc: Aberglasslyn (Maitland) NSW
Some showers this morning, and on the way to work in Singo.
Did not expect them, and they were not on the forecast.
Anyway, Singo missed the big downpours of other places in the Lower Hunter last week, so will still be some useful rain.
IF it sticks around today, I doubt we will be getting all that hot temps either.

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#1459079 - 26/03/2018 06:08 Re: NSW/ACT day to day weather [Re: Grant]
Knot Offline
Weatherzone Addict

Registered: 01/05/2014
Posts: 2560
Loc: Toronto N.S.W
Good steady rain for past few hours.
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