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#1458552 - 23/03/2018 14:41 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Mike Hauber Offline
Weatherzone Addict

Registered: 13/07/2007
Posts: 3817
Loc: Buderim
As I already stated, the drop in January was to a value a long way outside the range of what had occurred in the last 5 or so months.

And because of the way that SOI is calculated it is common for SOI to stay at close to the same level before switching to a neutral value all at once.

It is obvious that the recent rise in SOI is noise, and that the drop in January was a more significant signal of something changing.


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#1458553 - 23/03/2018 14:45 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Kino Offline
Weatherzone Addict

Registered: 10/08/2017
Posts: 3505
Loc: Wollongong, NSW, Aus
A -6 to a +10 change is absolutely not noise. Clear tropical wave activity propagating east to west, fuelled by a cold ENSO.


Edited by Kino (23/03/2018 14:48)

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#1458557 - 23/03/2018 15:36 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Mike Hauber Offline
Weatherzone Addict

Registered: 13/07/2007
Posts: 3817
Loc: Buderim
Its the MJO, which propogates west to east. MJO is usually considered noise. The SOI has been high when MJO is in Indian/Australian region, and low when it goes into Pacific. Rossy waves move east to west but are modulated within the MJO envelope.

Or maybe its not noise. And we went from la nina to almost el nino in January, then back to La Nina late in February, back to almost el nino in March. And we are about to go back into almost el nino in a couple weeks time as MJO goes Pacific again.

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#1458592 - 23/03/2018 18:38 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
RC Offline
Weatherzone Addict

Registered: 29/09/2007
Posts: 2601
Loc: near Rockhampton, Qld
I think Mike has a point. August to October the SOI shows consistently positive, which means lower then normal pressures over Darwin and higher then average over Tahiti. This would correspond with a reasonable spring rain events for my region. But come Summer it was like the tap was turned off, and the SOI then goes into major up's and downs.

You need to see those consistent positive values rather then see-sawing. See-Sawing to me represents the fluke rain events, not the consistent rain events.

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#1458600 - 23/03/2018 19:04 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Locke Offline
Weatherzone Addict

Registered: 27/12/2007
Posts: 4553
Loc: Brisbane
I would also argue that the SOI has been more positive than negative. This is why the 90 day value remains positive and is likely to be so for the near future.

The occasional WWB has interrupted this but the SOI has rebounded after each because the overall forcing is towards La Nina.
_________________________
This post and any other post by Locke is NOT an official forecast & should not be used as such. It's just my opinion & may or may not be backed by sound meteorological data. For official information, refer to Australian Bureau of Meteorology products.

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#1458603 - 23/03/2018 19:31 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: Locke]
ColdFront Offline
Meteorological Motor Mouth

Registered: 29/06/2008
Posts: 19046
Loc: The Beach.
Originally Posted By: Locke
I would also argue that the SOI has been more positive than negative.


.....and you'd be right.
_________________________


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#1458610 - 23/03/2018 20:00 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: Locke]
Mike Hauber Offline
Weatherzone Addict

Registered: 13/07/2007
Posts: 3817
Loc: Buderim
Originally Posted By: Locke
I would also argue that the SOI has been more positive than negative. This is why the 90 day value remains positive and is likely to be so for the near future.

The occasional WWB has interrupted this but the SOI has rebounded after each because the overall forcing is towards La Nina.


And I would not disagree with you about the 1st point.

On the second point I think the trend in most indicators is clearly away from La Nina and not towards La Nina, but you may have meant something different to trend by 'forcing'

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#1458611 - 23/03/2018 20:02 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Mike Hauber Offline
Weatherzone Addict

Registered: 13/07/2007
Posts: 3817
Loc: Buderim
Both ec and GFS now think the mjo will strengthen again.



So chance of a further significant WWB is increased. One thing though is the movement through the Pacific phases is quite quick on the current forecast.

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#1458637 - 23/03/2018 22:42 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: Mike Hauber]
Kino Offline
Weatherzone Addict

Registered: 10/08/2017
Posts: 3505
Loc: Wollongong, NSW, Aus
Originally Posted By: Mike Hauber
Its the MJO, which propogates west to east. MJO is usually considered noise. The SOI has been high when MJO is in Indian/Australian region, and low when it goes into Pacific. Rossy waves move east to west but are modulated within the MJO envelope.

Or maybe its not noise. And we went from la nina to almost el nino in January, then back to La Nina late in February, back to almost el nino in March. And we are about to go back into almost el nino in a couple weeks time as MJO goes Pacific again.


There is no MJO as shown in your graph. It is non existent. This wave, an Equatorial Rossby wave, has moved west from the Pacific resulting in these conditions

Originally Posted By: BoM
Equatorial Rossby wave activity, which was likely the most significant tropical wave associated with tropical cyclone Marcus, remains present across northern Australia. In its current location, the Rossby wave, a westward moving tropical pulse of low pressure, is reinforcing cross-equatorial flow into Australian longitudes and provides favourable conditions for enhanced tropical convection and tropical cyclone formation in the region.


While this Rossby Wave remains active, the chances of a WWB would remain low to non-existent.


Edited by Kino (23/03/2018 22:43)

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#1458638 - 23/03/2018 22:46 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: Kino]
ColdFront Offline
Meteorological Motor Mouth

Registered: 29/06/2008
Posts: 19046
Loc: The Beach.
Originally Posted By: Kino


Originally Posted By: BoM
Equatorial Rossby wave activity, which was likely the most significant tropical wave associated with tropical cyclone Marcus, remains present across northern Australia. In its current location, the Rossby wave, a westward moving tropical pulse of low pressure, is reinforcing cross-equatorial flow into Australian longitudes and provides favourable conditions for enhanced tropical convection and tropical cyclone formation in the region.


While this Rossby Wave remains active, the chances of a WWB would remain low to non-existent.



Absolutely Kino.
_________________________


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#1458662 - 24/03/2018 06:24 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: Kino]
Mike Hauber Offline
Weatherzone Addict

Registered: 13/07/2007
Posts: 3817
Loc: Buderim
Originally Posted By: Kino


There is no MJO as shown in your graph. It is non existent. This wave, an Equatorial Rossby wave, has moved west from the Pacific resulting in these conditions


For 30 day SOI:

First low value: Jan 8, MJO in phase 2
second low value feb 28, MJO in phase 2

First high value: feb 1, MJO in phase 7
Currently SOI near MJO cycle peak and MJO in phase 5

30 day SOI gets to its lowest values when MJO enters the Indian ocean - when the last 30 days the MJO has been mostly in the el nino favourable Pacific.

30 day SOI gets to its highest value as the MJO enters the Pacific - when the last 30 days has been mostly in the La Nina favourable Indian Ocean.

Originally Posted By: Kino

While this Rossby Wave remains active, the chances of a WWB would remain low to non-existent.


This Rossby wave contributed substantially to the strong westerly activity recently occurring in west Pacific. It will be gone by the time strong westerly activity is forecast later in the current forecast period. Rossby waves last a few days to maybe 2 weeks. As a wave they have an up part and a down part, both of which occur within a typical lifespan of less than 2 weeks. So cancel out when averaged over 30 days and Rossby waves never have any noticeable impact on 30 day SOI. They do have an impact on daily SOI figures.

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#1458711 - 24/03/2018 12:38 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: Mike Hauber]
Ronfishes Offline
Weatherzone Addict

Registered: 25/02/2013
Posts: 3911
Loc: Gordonvale
Originally Posted By: BoM


Pacific Ocean returns to neutral

La Niña has ended

_________________________

MTD: 37.8mm
YTD: 1693.4mm
18-19 Wet Season: 2458.2mm

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#1458716 - 24/03/2018 12:52 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
scott12 Offline
Weatherzone Addict

Registered: 10/11/2015
Posts: 1231
Loc: maadi Tully area
Yep BOM stated the following 2 weeks ago....


La Niña ends, El Niño-Southern Oscillation returns to neutral
The 2017–18 La Niña has ended. El Niño–Southern Oscillation (ENSO) indicators have eased back to neutral levels over the past several weeks. This means the ENSO Outlook has shifted from LA NIÑA to INACTIVE.
The end of the La Niña is clear in oceanic and atmospheric indices. Sea surface temperatures have warmed steadily since December, and are now in the neutral range. Waters beneath the surface have also warmed. In the atmosphere, cloudiness near the Date Line has returned to near-average levels, and trade winds are generally near average across the equatorial Pacific. Likewise, the Southern Oscillation Index (SOI) is well within the neutral range.
Most models indicate that ENSO-neutral is the most likely scenario through the southern hemisphere autumn and into winter. However, model accuracy during autumn is lower than at other times of year. A neutral ENSO pattern does not necessarily signify average rainfall and temperature for Australia. Rather, it indicates a reduced chance of prolonged very wet or dry, or very hot or cold conditions, and that other climate drivers may have greater influence over the coming months.
The weak and short–lived La Niña had relatively little effect on Australian rainfall patterns over the 2017–18 summer. However, it may have kept temperatures higher than average in southern parts of the country due to weather patterns being slower moving, and further south than normal.
The Indian Ocean Dipole (IOD) is currently neutral. IOD events are unable to form between December and April. Current outlooks suggest a neutral IOD for autumn and early winter.


Edited by Mick10 (25/03/2018 00:36)
Edit Reason: edited comments

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#1459225 - 26/03/2018 18:40 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Petros Offline
Meteorological Motor Mouth

Registered: 30/12/2002
Posts: 8071
Loc: Maffra, Central Gippsland, Vi...
Feb/Mar rainfall for N Qld coastal regions for this current weak La Nina can only be described as "incredible" for this "way down south southerner".

....when a Nylex gauges, capable of 275mm, overflow in one day, ....and not talking about mountain top locations!

How did we all perform with our climate-educated seasonal rainfall predictions for this period when we look back at the start of this thread???



....and we ignore what transpired, and continue our talk about looming dry conditions (like we have for months), ...while NE Qld is swimming - without reference to learnings that are sitting amongst huge rainfall total records.

Why dont we go back, analyse, and adjust our seasonal predictive models/concepts so we dont get this wrong next time.

If I was a farmer in NQ, based on this thread, I would have expected a continuation of record dry.


Edited by Petros (26/03/2018 18:48)

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#1459331 - 27/03/2018 07:53 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
RC Offline
Weatherzone Addict

Registered: 29/09/2007
Posts: 2601
Loc: near Rockhampton, Qld
I don't really think the rain that fell up north was really caused by the La Nina.

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#1459339 - 27/03/2018 08:25 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: Petros]
Mike Hauber Offline
Weatherzone Addict

Registered: 13/07/2007
Posts: 3817
Loc: Buderim
Originally Posted By: Petros


How did we all perform with our climate-educated seasonal rainfall predictions for this period when we look back at the start of this thread???



Certain posters have been regularly posting predictions of wet conditions, and it looks to me like the overall wet season for East Australia as a whole is still below average. I can't recall anyone forecasting dry conditions, but if they had they would have been more accurate.



Overall March looks to be above average, but with substantial areas in Qld, and most of NSW/VIC being below average I doubt it is enough to remove the dry anomalies from earlier in the season.


Edited by Mike Hauber (27/03/2018 08:25)

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#1459341 - 27/03/2018 08:38 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Flowin Offline
Weather Freak

Registered: 15/10/2017
Posts: 966
Loc: Pinjarra Hills, Qld
Calendar year to date precipitation relative to historical conditions:
http://www.bom.gov.au/water/landscape/#/...rate///2018/1/1

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#1459372 - 27/03/2018 10:33 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
RC Offline
Weatherzone Addict

Registered: 29/09/2007
Posts: 2601
Loc: near Rockhampton, Qld
I have a theory that minor La Ninas and minor El Nino's both create dry periods in Queensland.

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#1459382 - 27/03/2018 11:40 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
ifishcq Offline
Weather Freak

Registered: 31/01/2018
Posts: 134
Loc: Rockhampton - Xtra Dry Dust La...
< La Nina | El Nino >
WET............DRY..........V DRY


Edited by ifishcq (27/03/2018 11:40)
_________________________
“It's so dry the trees are bribing the dogs.”
Charles Martin

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#1459402 - 27/03/2018 13:54 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ifishcq]
Kino Offline
Weatherzone Addict

Registered: 10/08/2017
Posts: 3505
Loc: Wollongong, NSW, Aus
Originally Posted By: ifishcq
< La Nina | El Nino >
WET............DRY..........V DRY


Actually it's more like

La Nina....Neutral....El Nino
WET OR DRY OR AVERAGE

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