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#1390724 - 19/10/2016 12:35 Re: Streamflow Observation [Re: Seira]
Purnong Offline
Weather Freak

Registered: 30/01/2011
Posts: 118
Loc: Tooperang, SA
100 GL would cause some problems for sure, I think the 1992 levels were around 90 GL
Then again I read that 1974 was about 180 GL and 1956 was 300 GL so while it will cause low lying areas some problems there won't be widespread devastation

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#1390857 - 20/10/2016 20:09 Re: Streamflow Observation [Re: Purnong]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6966
Loc: Adelaide Hills.
The upper Murray may be expecting more rain - based on a look at the Bureau's Seasonal Streamflow Forecast to December. The same outlooks (October-December) for the North Para River at Penrice (SA) seem a little bit more than a curiosity (if it turns out that way), if I'm reading it accurately.

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#1390936 - 21/10/2016 20:32 Re: Streamflow Observation [Re: Purnong]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6966
Loc: Adelaide Hills.
Originally Posted By: Purnong
100 GL would cause some problems for sure, I think the 1992 levels were around 90 GL
Then again I read that 1974 was about 180 GL and 1956 was 300 GL so while it will cause low lying areas some problems there won't be widespread devastation

Where exactly are you getting these GL figures from smile ? A weir, a dam, where? I am unfamiliar with them.

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#1390938 - 21/10/2016 20:51 Re: Streamflow Observation [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6966
Loc: Adelaide Hills.
Originally Posted By: -Cosmic- (naz)
Originally Posted By: Purnong
Originally Posted By: -Cosmic- (naz)
Hi Purnong,

Interesting times.


I was thinking the current heavy falls upstream in Vic and NSW will have an impact along with the snow melt and any other rain for the rest of the year
Some people up there are starting to talk 1974 flood levels which were pretty major

Moisture from the Pacific Ocean can interact in the Mid-NSW/NE VIC region with plumes from the Indian Ocean when cut-off lows move inland. Warm SST currents travel from the Indonesian Through-Flow (ITF) from the Tropical North-western Pacific – cross-equatorial, bringing with them additional latent heat energy. Combined with warmer waters from a negative phase Indian Ocean Dipole (IOD), these can interact near Java, Indonesia, bringing additional moisture to NW WA coasts. This moisture then transitions to become a plume once it interacts with the northern edge of the westerlies (at the middle to upper tropospheric levels). These plumes encounter pressure, thickness (kinetic energy) and thermal temperature gradients as they move from coastal NW WA to coastal SE VIC. Near-stationary surface ridging will displace these plumes if it has the same alignment (i.e. NW-SE). As the westerly belt has been quite dominant, it can generate a “gap” across the Southeast, which means ridges will have difficulty maintaining a NW-SE alignment without eventually being pushed further east. The pattern was/is fairly dynamic*, southerly and/or sub-tropical, hence wet conditions in those areas.

* Dynamic as in changeable/more variability. Stagnant is like stagnating water or winds -- negligible change or motion.

Bold - I think whether or not 1974 levels occur this year in those regions dependents rather a lot on the frequency of moisture and its ability to rain-out.

A tropical disturbance (which veered south from near Java and became anchored between Geraldton and Perth WA, near-stationary) may have formed a blocking pattern for the SAM back before early May, which subsequently broke down after surface ridging (higher-pressure systems) moved more east, changing the prevailing wind direction. Just an idea, but food for thought smile .

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#1390941 - 21/10/2016 21:17 Re: Streamflow Observation [Re: Seira]
Purnong Offline
Weather Freak

Registered: 30/01/2011
Posts: 118
Loc: Tooperang, SA
Originally Posted By: -Cosmic- (naz)
Originally Posted By: Purnong
100 GL would cause some problems for sure, I think the 1992 levels were around 90 GL
Then again I read that 1974 was about 180 GL and 1956 was 300 GL so while it will cause low lying areas some problems there won't be widespread devastation

Where exactly are you getting these GL figures from smile ? A weir, a dam, where? I am unfamiliar with them.


They were just the historic flows that I read about somewhere
There is an excellent graphic of the current river flows and levels in the below link

http://livedata.mdba.gov.au/system-view

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#1390958 - 21/10/2016 22:46 Re: Streamflow Observation [Re: Purnong]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6966
Loc: Adelaide Hills.
Thanks for the link.

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#1391646 - 29/10/2016 14:39 Re: Streamflow Observation [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6966
Loc: Adelaide Hills.
Dewpoint temperature may exceed the overnight low in the next 3 days.

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#1392180 - 04/11/2016 17:20 Re: Streamflow Observation [Re: Seira]
Purnong Offline
Weather Freak

Registered: 30/01/2011
Posts: 118
Loc: Tooperang, SA
Flood advice given now for the lower Murray

http://www.bom.gov.au/cgi-bin/wrap_fwo.pl?IDS20371.html

FLOOD ADVICE MESSAGE FOR RIVER MURRAY SHACK AREAS

The State Emergency Service (SES) advises that, as a result of the recent high rainfall, flows in the River Murray are increasing. Predicted water levels are likely to cause minor flooding in the shack areas between Cadell and Mannum.

Shack areas that are likely to be affected include Morgan, Brenda Park, Scotts Creek, Walker Flat and Bowhill.

Flows into South Australia are currently 55 GL/Day and will increase to around 65 GL/Day during the coming week. They are expected to remain high into December.

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#1392181 - 04/11/2016 17:23 Re: Streamflow Observation [Re: roves]
Purnong Offline
Weather Freak

Registered: 30/01/2011
Posts: 118
Loc: Tooperang, SA
Originally Posted By: roves
60GL is enough for yabbies to get going so im happy with that though would love to see it go over 100GL to really give the flood plains a good drink.


I read they are predicting 95GL by the end of December so its getting there

http://www.adelaidenow.com.au/news/south...cce0289177b145b

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#1392631 - 08/11/2016 20:49 Re: Streamflow Observation [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6966
Loc: Adelaide Hills.
Local [Experimental!] Model Output suggests Mallee affected near the 13th of November.

Units, deg C/d, deg C/d, deg C/d, mm, dir (3 pm), dir (9 am)
Date, Max =, Min =, dpt =, Rain, tmWind, tnWind,

[Output]
12/11/2016, 27.7, 6, 3.8, 0, N, N,
13/11/2016, 15.9, 8.5, 9.4, 26.9, E, SE,
14/11/2016, 27.2, 9.5, 9, 1.2, N, NNW

See wind direction.

smile


Edited by -Cosmic- (naz) (08/11/2016 20:54)

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#1392822 - 09/11/2016 22:57 Re: Streamflow Observation [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6966
Loc: Adelaide Hills.
The previous post contains erroneous data -- the date was not reset to 8/11/2016, and remained on a previous tested data set date. Experimental it is.

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#1393288 - 12/11/2016 16:20 Re: Streamflow Observation [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6966
Loc: Adelaide Hills.
The dewpoint rose sharply yesterday afternoon, the vertical profile of the lower atmosphere becoming quite unstable with surface heating (i.e. colder-air characteristics above a mixed, warmer surface layer). Earlier signs of severe weather from about 1 pm ACDT near Hahndorf. The pressure fell below 1000 hPa which suggested stronger surface troughing (uplift with mixing) and convergence. This was not helped by the extent of troughing all the way to tropical regions in the north. It may have generated a huge temperature imbalance north-south, as the thickness raised inland temperatures and drew in moisture from the west. Hail was not only possible, but became a reality.

Minor flooding and large (2-3 cm) hail observed from Glen Osmond to Aldgate.

As note of benefit, the current system may retrograde slightly to become temporarily near-stationary over TAS/SE Australia, bringing a narrower plume of concentrated, higher-humidity air from the deep south NE-wards, forcing near-surface temperatures down, and shower activity to persist for another day or so over these areas.


Edited by -Cosmic- (naz) (12/11/2016 16:27)

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#1393771 - 14/11/2016 18:00 Re: Streamflow Observation [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6966
Loc: Adelaide Hills.
Riverland fruit-growers badly hit by Thunderstorms 11th-12th November frown . Falls between 30 and 70 mm recorded over a 3-day period in hills area.

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#1394740 - 27/11/2016 14:05 Re: Streamflow Observation [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6966
Loc: Adelaide Hills.
Notes: 24th of November 9:10 pm ACDT [Updated from 23rd, 8:30 pm]
It has become increasingly clear what has been happening recently…

There now appears to be a persistent plume of higher 500-1000 mb thickness air from the tropics (Broome-Darwin region) migrating S-SE into the Australian continental interior, which is not only driving interior temperatures up due to sensible heat, but pushing the northern edge of the west-coast ridge, south – compressing it as it drifts east. This will not cause fronts to buckle because the western, drifting ridge (which narrows north-south when it reaches the higher thickness) is weakened. The NW-SE troughing and diffuse regions of tropical lower-pressure disturbance across the interior are able to interact with the southerly upper trough. 700-500 hPa winds and moisture from the south may contribute to this by anchoring (at 500 hPa) in the NE region of the compressed ridge. This is also a mechanism for tropical (700 hPa), interior moisture to drift down, hitting a large temperature gradient.

Compression means the pressure-gradient force becomes greater than the Coriolis Force/Effect. This can induce troughs.

If this continues, there seems a greater risk of more thunderstorm activity in the NE quadrant of the compressed ridge [Mallee/Riverland/SW NSW], plus isolated to scattered showers across SE Coasts. Also, areas adjacent Alice Springs may be a risk of significant weather outbreaks. These are humid sub-tropical conditions. The western ridging is acting as a catalyst.

This is valid roughly (+/-) 2 weeks from the 24th of November.

Again, these are my views, so I cannot guarantee their accuracy. I can however point in a reasonable direction smile .


Edited by -Cosmic- (naz) (27/11/2016 14:07)

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#1394747 - 27/11/2016 14:16 Re: Streamflow Observation [Re: Seira]
teckert Offline
Weatherzone Moderator

Registered: 27/05/2001
Posts: 17478
Loc: NE suburbs, Adelaide, South Au...
Think you are on the money there. Looks humid, thundery conditions for much of central and SE Australia from about the second week of December onwards.

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#1394889 - 28/11/2016 17:18 Re: Streamflow Observation [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6966
Loc: Adelaide Hills.
It was partially a precautionary note smile -- about the risk of significant weather outbreaks, hopefully not understating it.

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#1395592 - 03/12/2016 12:30 Re: Streamflow Observation [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6966
Loc: Adelaide Hills.
Dynamics have shifted slightly...however dew points are very interesting for next probable change -- ~ 18-to-20 range on ACCESS/GFS. That's a lot of moisture, I think.

Unless I'm mistaken, this moisture will (locally) be drifting off the eastern slopes of the Mount Lofty Ranges (NE-to-SW) with a north-westerly wind, because the higher temperatures are to the NE, lower, SW.


Edited by -Cosmic- (naz) (03/12/2016 12:36)

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#1395810 - 04/12/2016 11:52 Re: Streamflow Observation [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6966
Loc: Adelaide Hills.
19-20 C, near 90% RH.

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#1396182 - 06/12/2016 21:55 Re: Streamflow Observation [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6966
Loc: Adelaide Hills.
Originally Posted By: -Cosmic- (naz)
19-20 C, near 90% RH.

A note about humid sub-tropical conditions settling in, for the first event, with 6.6 mm to 2 pm that day.

Clarity: 18-to-20 probable/observed dewpoint range applies to end of forward 2-week period (i.e. 8th of Dec).


Edited by -Cosmic- (naz) (06/12/2016 21:59)

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#1396769 - 10/12/2016 15:19 Re: Streamflow Observation [Re: Seira]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 6966
Loc: Adelaide Hills.
Rewritten 8:35 pm ACDT:
It seems the southern-ocean 500-hPa troughs have been aligning to the north-eastern flank of the west-coast surface ridge, bringing with them milder temperatures due to travelling so far north (they gain latent heat), ...in the process they seem to be destabilising the northern thickness plumes (generating pressure gradients) and increasing mixing. 21.2 mm in 32 hours to 8 pm, 8th, not isolated stuff going by the area map for SA. There may potentially more on the way. A rough calculation gives:
Vapour pressure: 22.4 hPa (32/22, max-min Tuesday)
Dewpoint: 19.3 C
Surface barometric pressure: 995 hPa
Precipitable-Water: 25-40 mm.

The reference below may also help smile .
-------------------------------------------------------------

Post #1245515 - 03-03-2014 11:27 PM:

HypothesisIs Southern Australia becoming more Humid Sub-tropical?

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