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#1441050 - 13/11/2017 08:09 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: Mega]
Kino Offline
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Registered: 10/08/2017
Posts: 1253
Loc: Wollongong, NSW, Aus
Originally Posted By: Mega
And check out the forecast MSLP difference between 2016 & 2017 as per UKMET, absolutely nothing alike. Everything on that 2017 chart looks much more conducive for a wetter summer than last year, at least for QLD & NSW. VIC less affected, as usual.




Thatís a great graphic. Hard to argue against that classic signature. Loving the higher pressure over southern oceans, should lead to a decent monsoon as well.

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#1441056 - 13/11/2017 09:48 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Snapper22lb Offline
Weather Freak

Registered: 17/02/2015
Posts: 182
Loc: Golden Beach
Kino,(or others) could you please explain why high pressure in the Southern Oceans could enhance monsoon activity? Thanks in advance.

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#1441057 - 13/11/2017 10:09 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: Snapper22lb]
Kino Offline
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Registered: 10/08/2017
Posts: 1253
Loc: Wollongong, NSW, Aus
Originally Posted By: Snapper22lb
Kino,(or others) could you please explain why high pressure in the Southern Oceans could enhance monsoon activity? Thanks in advance.


Hi Snapper22klb - it's all about the processes that lead to monsoonal development known as Hadley Cells - colder waters over the southern oceans = higher pressure; higher pressure further south means the Hadley Cell which drive the monsoon can move form further south allowing the inter-tropical convergence zone to also form further south (not forgetting that those NE'erly trades swing to NW'erlies as they cross the equator due to the Coriolis Effect).



Edited by Kino (13/11/2017 10:13)

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#1441058 - 13/11/2017 10:13 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Chris Stumer Offline
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Registered: 28/01/2010
Posts: 1596
Loc: Kingaroy
The monsoon trough forms when northwesterly winds converge with the south east trade winds so in theory stronger high pressure over the southern ocean should lead to a stronger monsoon trough, it should also increase the chances of westward moving cyclones.

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#1441067 - 13/11/2017 12:36 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Locke Offline
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Registered: 27/12/2007
Posts: 4360
Loc: Brisbane
I would also assume that persistent higher pressures in the SE Pacific would aid in the upwelling of colder water off South America.
_________________________
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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#1441068 - 13/11/2017 12:53 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Snapper22lb Offline
Weather Freak

Registered: 17/02/2015
Posts: 182
Loc: Golden Beach
Thanks for info all - will do some further reading as well. Cheers

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#1441072 - 13/11/2017 13:13 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Chris Stumer Offline
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Registered: 28/01/2010
Posts: 1596
Loc: Kingaroy
I remember reading somewhere that La Nina favors a positive phase of the Southern Annular Mode.

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#1441079 - 13/11/2017 14:47 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
CoastalStorm22 Offline
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Registered: 10/07/2006
Posts: 2699
Loc: Lane Cove, Sydney, NSW
The SAM is constantly positive these days La Nina or not, seems to make no difference, which is part of the reason for the long term drying trend in western and southern Aus.

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#1441207 - 15/11/2017 10:19 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Chris Stumer Offline
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Registered: 28/01/2010
Posts: 1596
Loc: Kingaroy
The SOI seems to dropping back to more neutral levels.

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#1441212 - 15/11/2017 10:53 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Locke Offline
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Registered: 27/12/2007
Posts: 4360
Loc: Brisbane
MJO signal for the coming month seems to be very weak and unpredictable.
_________________________
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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#1441213 - 15/11/2017 11:09 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: Locke]
CoastalStorm22 Offline
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Registered: 10/07/2006
Posts: 2699
Loc: Lane Cove, Sydney, NSW
Originally Posted By: Locke
MJO signal for the coming month seems to be very weak and unpredictable.


Isn't that typical Nina behavior of the MJO?

Yes Chris, SOI not looking very special.


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#1441219 - 15/11/2017 12:38 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Locke Offline
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Registered: 27/12/2007
Posts: 4360
Loc: Brisbane
I'm not sure what's actually typical.

I think you then need to start to look at seasonality combined with long term averages also taking into account that even within La Nina's, each can have different characteristics.

I do know that in January 2011, the MJO was very strong in phase 5 when the Brisbane floods occurred.
_________________________
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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#1441252 - 15/11/2017 16:38 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Squeako_88 Offline
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Registered: 23/09/2005
Posts: 401
Loc: Elimbah 4516
Hi Locke,

Looking at the MJO gragh back in January 2011 it looked like it was weak until the end of the flood event when it rapidly intensify into Phase 6.

http://www.bom.gov.au/climate/mjo/graphics/archive/MJO_phase/201101.phase.90days.gif
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#1441253 - 15/11/2017 16:51 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Mike Hauber Offline
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Registered: 13/07/2007
Posts: 2750
Loc: Buderim
A moderately strong but short lived WWB resulted from that MJO event which helped give birth to Yasi and as the trade winds snapped back quickly that pushed Yasi onto the coast.

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#1441287 - 16/11/2017 08:34 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Mike Hauber Offline
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Registered: 13/07/2007
Posts: 2750
Loc: Buderim
The possible warm Kelvin wave is approaching the cool pool, so it will be interesting to see what happens. I hadn't expected the cool pool to bounce back so quickly after the end of the last cool Kelvin wave. There is some hint of maybe a second cool Kelvin wave when looking at TAO data for 2N, or maybe its just the strength of the current trade wind burst.



Trade wind forecasts going forward are a bit unclear. It seems like trade winds are generally weakening after the recent strong burst, with some areas of westerly anomalies in the forecast, but more easterly anomalies than westerly overall. There is also disagreement between EC, CFS and GFS on where the westerly and easterly anomalies might be.

There does appear to be some likelihood that easterly anomalies will be primarily a long way east, which is quite unusual, with weak westerlies in the west. My current thinking is that wind anomalies further east have a greater impact on the surface and lesser impact on the subsurface.

To guess at a possible impact of the warm Kelvin Wave it looks like currently heat content in the west has surged by about 0.075 10^10 J/m2. (The 0.05 contour is progressing east but the 0.1 contour has stalled). The cool anomalies in the east are mostly under 0.1, with a solid core above 0.1. So the core would remain but significantly weaker, and some areas would be pushed above 0.

To this add further warming if there is a cool Kelvin wave now in progress, as the cool Kelvin wave clears the area (0.02 to 0.05?), any error in my estimation of the strength of the warm Kelvin wave, and any further impacts from trade wind anomalies in the next week or three.

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#1441297 - 16/11/2017 09:51 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Mike Hauber Offline
Weatherzone Addict

Registered: 13/07/2007
Posts: 2750
Loc: Buderim
The 90 day SOI may be within La Nina thresholds. But looking at the last 90 day's SLP map Darwin is just barely within the region of low pressure anomalies, and most of the rest of the country has been in a region of high pressure anomalies.

High pressure anomaly in western Coral sea and low pressure further east is not helpful either.


[/quote]

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#1441299 - 16/11/2017 09:57 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Chris Stumer Offline
Weatherzone Addict

Registered: 28/01/2010
Posts: 1596
Loc: Kingaroy
I'd imagine if the atmosphere couples with the cool Pacific then the SOI will take off. In 2007 the SOI was the last indicator to reach La Nina levels.

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#1441307 - 16/11/2017 10:54 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Mike Hauber Offline
Weatherzone Addict

Registered: 13/07/2007
Posts: 2750
Loc: Buderim
More like if the ocean couples with the atmosphere. SOI went +ve, and enhanced trade winds appeared in July. Cool SSTs appeared in August. SOI and trade winds are currently within BOM thresholds for La Nina. SSTs are not.

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#1441323 - 16/11/2017 14:14 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
CoastalStorm22 Offline
Weatherzone Addict

Registered: 10/07/2006
Posts: 2699
Loc: Lane Cove, Sydney, NSW
I see the latest climate outlook coming on board with what POAMA has been saying. Which as we know is contrary to what some other models are saying.

I think we might see another strong positive Subtropical Indian Ocean Dipole event this summer if those persistent SST anomalies are anything to go by. I believe last years was a strong event.

Another wet summer for WA perhaps?

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#1441336 - 16/11/2017 16:28 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Locke Offline
Weatherzone Addict

Registered: 27/12/2007
Posts: 4360
Loc: Brisbane
Extended GFS has been quite variable on recent runs in terms of strength and westward penetration of the trades with the latest runs having dispensed with strong WWB's seen in a couple of earlier runs.

As we get into cyclone season a lot hinges on the formation of tropical lows and cyclones.
_________________________
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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