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#74443 - 19/07/2005 12:38 Very high atmospheric pressure
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2137
Loc: Manilla, near Tamworth NSW
Just now the air pressure is 1033 hPa here. Is this unusually high?

On a world scale, the Siberian High seems to be exceptional:

"The highest recorded atmospheric pressure, 108.57 kPa (1085.7 mbar or 32.06 inches of mercury), occurred at Tonsontsengel, Mongolia, 19 December 2001."
http://en.wikipedia.org/wiki/Atmospheric_pressure

What is known about Australian high pressure systems, their variation, and their extremes?

Is it a myth that high atmospheric pressure affects people?
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#74444 - 19/07/2005 13:32 Re: Very high atmospheric pressure
Blair Trewin Offline
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Registered: 13/07/2001
Posts: 3825
Loc: Melbourne, Australia
The Tosontsengel pressure was based on a highly dubious method of reducing pressure to mean sea level (Tosontsengel is at about 1700m elevation). The lowest near sea level was 1083 at a Siberian site.

Off the top of my head I think the Australian record is around 1044, and the highest I can remember seeing in the Southern Hemisphere is 1048.

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#74445 - 19/07/2005 14:04 Re: Very high atmospheric pressure
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2137
Loc: Manilla, near Tamworth NSW
Thanks, Blair.

What conditions would set up record high pressures in Australia? What month is likely?

Regarding the correction to sea level, surely we have the same problem. I find it amazing that our system of forecasting works so well, considering it is based on imaginary flows of air deep underground!
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#74446 - 19/07/2005 15:52 Re: Very high atmospheric pressure
Blair Trewin Offline
Weatherzone Addict

Registered: 13/07/2001
Posts: 3825
Loc: Melbourne, Australia
The extreme highest pressures in Australia are in Tasmania, and occur in winter (June 1967 IIRC). The further south you are the better your chances.

The main issue with the correction to MSLP is that it requires one to estimate the temperature of a notional column of aim between the station height and sea level. The approximate uncertainty arising from this is about 0.1 hPa per 100m elevation per degree C uncertainty.

It's not a huge issue in Australia because most of our stations are at low elevation, and because we don't experience the huge inversions that make surface temperature unrepresentative of free-atmosphere temperatures at some locations. (Australia also uses monthly mean temperature rather than current surface temperature for the correction). In the case of Tosontsengel, the surface temperature at the time was probably about 20 C lower than the free-atmosphere temperature at the same height (it is a major frost hollow and regularly gets temperatures well below -40), and the station height is 1700m, meaning that the pressure was unrepresentatively high by about (20 x 17 x 0.1) = 34 hPa.

WMO recommends not reporting MSLP at stations above 800m elevation - most countries with large areas above this height report 850 or 700 hPa heights instead (the US and Mongolia are two major exceptions).

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#74447 - 19/07/2005 18:49 Re: Very high atmospheric pressure
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2137
Loc: Manilla, near Tamworth NSW
Tosontsengel:

http://maps.google.com/maps?ll=48.739986,98.286953&spn=0.072570,0.105512&t=k&hl=en
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#74448 - 19/07/2005 19:45 Re: Very high atmospheric pressure
Keith Offline
Meteorological Motor Mouth

Registered: 16/12/2001
Posts: 6453
Loc: Kings Langley, NSW
I seem to recall seeing a year or so ago, a high of 1052mb over the Falkland Islands (~Lat 53S).

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#74449 - 19/07/2005 19:52 Re: Very high atmospheric pressure
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2137
Loc: Manilla, near Tamworth NSW
My computer has been locking up. Seems to be something to do with the link I gave.

Pity. It's a nice image.
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#74450 - 19/07/2005 20:06 Re: Very high atmospheric pressure
Mick10 Offline
Weatherzone Moderator

Registered: 02/11/2001
Posts: 25304
Loc: Kirwan, Townsville - NQld.
i have been sitting on 1037hPa most the day. been cloudy with some lunch time drizzle.
both my wife and I have been getting slight headaches all day, any chance it could be due to the higher pressure?
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#74451 - 19/07/2005 20:28 Re: Very high atmospheric pressure
Thunder head Offline
Member

Registered: 24/05/2005
Posts: 1274
Loc: Berwick, Melbourne
I've been very hostile towards my friends at school, maybe the high pressure alters peoples moods......

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#74452 - 19/07/2005 21:28 Re: Very high atmospheric pressure
TrenthamStormchasers Offline
Meteorological Motor Mouth

Registered: 15/04/2001
Posts: 6258
Loc: Trentham 705m
I'll put my hand up for a case of stuffed sinuses that have been getting worse over the past couple of days....that fits! But StormChaserDog's arthritis is just fine atm.....

I remember a nasty high in June 2000 of 1040something frown ...and yet to the north just on sunset was a hint of castellanus laugh

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#74453 - 20/07/2005 11:02 Re: Very high atmospheric pressure
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2137
Loc: Manilla, near Tamworth NSW
This morning eleven NSW stations have pressures over 1040 hPa.

Albury 1041.2, Khancoban 1042.2.

Khancoban is at 339 m amsl. Does that make it a bit dodgy?
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#74454 - 20/07/2005 11:21 Re: Very high atmospheric pressure
Blair Trewin Offline
Weatherzone Addict

Registered: 13/07/2001
Posts: 3825
Loc: Melbourne, Australia
I wouldn't have thought the height was a major problem at Khancoban, but something funny seems to be going on there because they had a sudden drop of 0.8 between 10 and 11.

At some major stations, the records (using 3-hourly data only for historical consistency) are:

Melbourne 1041.2
Mildura 1040.2
Canberra 1042.9
Wagga 1042.3
Sydney 1040.0
Adelaide AP 1040.5
Launceston AP 1044.3
Hobart 1043.6

Most of the NSW and Victorian records were set on 7-8 July 1987 (except for Mildura which was on 17 May 1973, as was Adelaide). The Tasmanian records were on 7 June 1967.

None of these records have been broken (yet), although several are getting within striking distance (Melbourne 1040.5, Mildura 1039.2, Sydney 1039.0).

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#74455 - 20/07/2005 12:15 Re: Very high atmospheric pressure
Keith Offline
Meteorological Motor Mouth

Registered: 16/12/2001
Posts: 6453
Loc: Kings Langley, NSW
Quote:
Originally posted by mick10:
i have been sitting on 1037hPa most the day. been cloudy with some lunch time drizzle.
both my wife and I have been getting slight headaches all day, any chance it could be due to the higher pressure?
Well when my head or arthritis start aching, it's often due to the barometer falling...right onto the source of the affliction.. laugh :cheers:

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#74456 - 20/07/2005 12:21 Re: Very high atmospheric pressure
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2137
Loc: Manilla, near Tamworth NSW
Blair, when you say "3-hourly data", does that mean the readings taken at 03:00, 06:00, etc.?
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#74457 - 20/07/2005 12:47 Re: Very high atmospheric pressure
Sonde Offline
Weather Freak

Registered: 27/03/2003
Posts: 282
Loc: Clemton Park 2206
yssy sydney airport toped out at 1039.4 at 9:40 and 9:50am

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#74458 - 20/07/2005 12:49 Re: Very high atmospheric pressure
Blair Trewin Offline
Weatherzone Addict

Registered: 13/07/2001
Posts: 3825
Loc: Melbourne, Australia
Quote:
Originally posted by Surly Bond:
Blair, when you say "3-hourly data", does that mean the readings taken at 03:00, 06:00, etc.?
Yes.

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#74459 - 20/07/2005 12:50 Re: Very high atmospheric pressure
Keith Offline
Meteorological Motor Mouth

Registered: 16/12/2001
Posts: 6453
Loc: Kings Langley, NSW
I don't know when Sydney's record of 1040 was achieved but the reading I had here at 10 am today of 1039.7 was the highest in 31 years of record.
:cheers:

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#74460 - 20/07/2005 13:18 Re: Very high atmospheric pressure
Papy_Zapy Offline
Member

Registered: 18/05/2005
Posts: 507
Loc: Melbourne
Where these records made during dry or wet years? Is there any correlation?

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#74461 - 20/07/2005 13:59 Re: Very high atmospheric pressure
Blair Trewin Offline
Weatherzone Addict

Registered: 13/07/2001
Posts: 3825
Loc: Melbourne, Australia
Quote:
Originally posted by Keith:
I don't know when Sydney's record of 1040 was achieved but the reading I had here at 10 am today of 1039.7 was the highest in 31 years of record.
:cheers:
7 July 1987. What did you peak at that day?

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#74462 - 20/07/2005 16:23 Re: Very high atmospheric pressure
Thunder head Offline
Member

Registered: 24/05/2005
Posts: 1274
Loc: Berwick, Melbourne
Melbourne City topped out at 1040.5hPa yet I saw CUMULUS going up, probably some 3000ft big eek someone please explain!

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