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#1442662 - 29/11/2017 09:49 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: Petros]
ColdFront Offline
Meteorological Motor Mouth

Registered: 29/06/2008
Posts: 18617
Loc: The Beach.
Originally Posted By: Petros
.... on the potential development of a La Nino early next year.


Well that would cover two out of three options.

The effects of a volcano depend on many variables.
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#1442672 - 29/11/2017 10:33 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: Petros]
Locke Offline
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Registered: 27/12/2007
Posts: 4481
Loc: Brisbane
Originally Posted By: Petros
....and meanwhile flooding rain is set to arrive in SE Aus over coming days, and a period of cooler than average weather.

I note that AV has started to consider the impact if a major eruption of the Bali volcano occurred, on the potential development of a La Nino early next year.

Would add another variable to the discussion on this thread!


The last 2 major volcanic eruptions occurred during the lead in to significant El Nino events.
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#1442675 - 29/11/2017 10:43 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Kino Online   content
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Registered: 10/08/2017
Posts: 2690
Loc: Wollongong, NSW, Aus
Meanwhile I think we are really starting to see the atmosphere and La Nina couple here with broad instability and above average rain and below average temps forecast. Very La Nina'esque IMO. Hopefully this pattern pushes well into summer and we get a few southern dropping decaying one-eyed-whirly-things pass us by with big rainfalls.

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#1442681 - 29/11/2017 11:12 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: Locke]
CoastalStorm22 Offline
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Registered: 10/07/2006
Posts: 2856
Loc: Lane Cove, Sydney, NSW
Originally Posted By: Locke
Originally Posted By: Petros
....and meanwhile flooding rain is set to arrive in SE Aus over coming days, and a period of cooler than average weather.

I note that AV has started to consider the impact if a major eruption of the Bali volcano occurred, on the potential development of a La Nino early next year.

Would add another variable to the discussion on this thread!


The last 2 major volcanic eruptions occurred during the lead in to significant El Nino events.


I wonder if that was just coincidence, or if the eruptions actually caused these El Nino's?
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#1442776 - 29/11/2017 20:31 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Chris Stumer Offline
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Registered: 28/01/2010
Posts: 1823
Loc: Kingaroy
If the volcano in Bali does a Mt Tambora or worse, then we would be in trouble from the climatic effects.

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#1442778 - 29/11/2017 20:41 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Petros Offline
Meteorological Motor Mouth

Registered: 30/12/2002
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Loc: Maffra, Central Gippsland, Vi...
Re volcano effect, I've no idea, to clarify, I believe that AV suspects that a major eruption in Bali would have a detrimental effect on the potential development of La Nina for the Aus region over the next 4-5 months due to it near equatorial location. And for my 2 bobs, agree. Big impact on reducing incoming heat to earth.

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#1442860 - 30/11/2017 11:07 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: CoastalStorm22]
Locke Offline
Weatherzone Addict

Registered: 27/12/2007
Posts: 4481
Loc: Brisbane
Originally Posted By: CoastalStorm22
Originally Posted By: Locke
Originally Posted By: Petros
....and meanwhile flooding rain is set to arrive in SE Aus over coming days, and a period of cooler than average weather.

I note that AV has started to consider the impact if a major eruption of the Bali volcano occurred, on the potential development of a La Nino early next year.

Would add another variable to the discussion on this thread!


The last 2 major volcanic eruptions occurred during the lead in to significant El Nino events.


I wonder if that was just coincidence, or if the eruptions actually caused these El Nino's?


Very difficult to say. In both cases the transition into El Nino had already begun. What we can't tell is what the eruptions did to the amplitude of the events (inclusive of the temperature responses at the time).
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#1442864 - 30/11/2017 11:15 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Mike Hauber Offline
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Registered: 13/07/2007
Posts: 3360
Loc: Buderim
Crazy WWB

At the end of the 14 day GFS forecast so firmly in probably won't happen territory....

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#1442866 - 30/11/2017 11:20 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Mike Hauber Offline
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Registered: 13/07/2007
Posts: 3360
Loc: Buderim
Research suggests that a strong volcanic eruption can significantly cool the tropics. As the land cools faster than ocean the Australian region cools relative to the east Pacific and the walker circulation is weakened and a trend towards el nino conditions result.

This is for very strong volcanic eruptions that launch significant amounts of ash into the stratosphere where it stays for a year or three. Most major eruptions don't reach so high and the ash can be rained out within a few weeks so don't have the same impact. Some volcanoes can erupt for months, so perhaps a sustained ash plume in Indonesia could cause local cooling which would also encourage a weakening of the walker circulation.

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#1442905 - 30/11/2017 14:48 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Beltane Offline
Weather Freak

Registered: 15/10/2001
Posts: 456
Loc: Warriewood 2102 NSW
For example, the powerful eruption in 1991 of Mt. Pinatubo (2nd largest of the 20th century) released an enormous volume of aerosols and dust into the stratosphere.

Sulfur dioxide oxidized in the atmosphere to produce a haze of sulfuric acid droplets, which gradually spread throughout the stratosphere over the year following the eruption. This injection of aerosols into the stratosphere is thought to have been the largest since the eruption of Krakatoa in 1883.

This very large stratospheric injection resulted in a reduction in the normal amount of sunlight reaching the Earth's surface by roughly 10%. This led to a decrease in northern hemisphere average temperatures of 0.50.6 C and a global fall of about 0.4 C, and at the same time, the temperature in the stratosphere rose to several degrees higher than normal, due to absorption of radiation by the aerosol.

The stratospheric cloud from the eruption persisted in the atmosphere for three years after the eruption, and was clearly visible in Sydney during dawn and dusk. The sunrises and sunsets at that time were quite brilliant.
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#1442915 - 30/11/2017 15:35 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
_Johnno_ Offline
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Registered: 08/11/2009
Posts: 1745
I am led to believe major volcano eruptions in the tropics distrupt trade winds and lead to more westerly anomalies more wwbs which therefore lead to more dominance of El Nino in the Pacific. I don't think it was a coincident that Pinnitubo blew in 1991 and we had four years in a row of El Nino or thresholds of El Nino between 1991-94 which caused major drought to QLD and northern NSW but oddly enough the southern states saw heavy rain and even flooding during this period especially in 92-93.
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#1442917 - 30/11/2017 15:36 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
_Johnno_ Offline
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Registered: 08/11/2009
Posts: 1745
Which makes it even more impressive that global temp anomaly dropped 0.5c after Pinnitubo blew while El Ninos dominated the Pacific.. Imagine if it had the impact of creating more La Nina's.. The global temp would of dropped more possibly double up to 1c.


Edited by _Johnno_ (30/11/2017 15:37)
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#1442965 - 30/11/2017 19:42 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
mammatus meestrus Offline
Cloud Gazer

Registered: 20/11/2008
Posts: 49
Loc: lennox head
Meanwhile, in the real world, in this case sub-tropical coastal NSW (highly susceptible to ENSO derived Pacific moisture fluctuations) 235 mm for Nov, after 211 for Oct.
Another cool, cloudy day with heavy showers to go with the rest of the last 2 months of Spring.

Warm, humid, unstable tropical air dominates: classic La Nina conditions.


Edited by mammatus meestrus (30/11/2017 19:44)

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#1442976 - 30/11/2017 20:55 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Mega Offline
Meteorological Motor Mouth

Registered: 03/02/2003
Posts: 7272
Loc: Maryborough, Wide Bay, QLD
That yucky orange shade is slowly being replaced by green again on CFSv2's precip anomaly charts for Jan. Hope it continues.

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#1442988 - 30/11/2017 21:52 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Chris Stumer Offline
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Registered: 28/01/2010
Posts: 1823
Loc: Kingaroy
I wonder if 1816 was an El Nino year after the 1815 eruption of Mt Tambora?

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#1443020 - 01/12/2017 07:15 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: Chris Stumer]
DarrylS Offline
Weather Freak

Registered: 07/12/2011
Posts: 120
Loc: Camp Hill, QLD
Originally Posted By: Chris Stumer
I wonder if 1816 was an El Nino year after the 1815 eruption of Mt Tambora?


You might find this report from the International Journal of Climatology which gives year by year reports of drought on Australia's east coast: "Rainfall variations in south-eastern Australia: 1788-1860"

That report says that there was a severe drought around Sydney from 1809 to 1815, and then again from 1824 to 1830. There were dryer conditions in 1816, but Feb, May, June, Oct and Nov 1816 actually had wet conditions around Sydney. The years 1817-18 had an abundant harvest and also insect plagues, suggesting pretty good growth conditions.

Hope that helps.
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#1443115 - 01/12/2017 14:58 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Chris Stumer Offline
Weatherzone Addict

Registered: 28/01/2010
Posts: 1823
Loc: Kingaroy
Thanks for the link. GFS seems to be easing off the strength of the predicted WWB and is increasing the strength of the trade wind burst. My thinking is that the MJO is stalled in the western Pacific, that could be why GFS keeps on throwing up WWBs.

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#1443139 - 01/12/2017 16:47 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Funkyseefunkydo Offline
Weather Freak

Registered: 30/04/2007
Posts: 710
Loc: East Lake Macquarie
Regarding volcano interruptions in atmosphere. This tweet is a nice graph.

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#1443149 - 01/12/2017 17:25 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
ozone doug Offline
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Registered: 06/11/2006
Posts: 1874
Loc: Roma SW QLD Eye to the West...
Good work Darryl S ,For that link.
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#1443215 - 02/12/2017 05:04 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Mega Offline
Meteorological Motor Mouth

Registered: 03/02/2003
Posts: 7272
Loc: Maryborough, Wide Bay, QLD
So BoM went from this:



to this:

I mean, I hate to be that guy but...that's some backflip in such a short a short space of time. Hard to believe there was any major changes in the modelling to influence their sudden switch from dry to wet.

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