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#1440957 - 11/11/2017 01:44 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Pooraka Offline
Weather Freak

Registered: 24/02/2006
Posts: 119
Loc: Pooraka, Adelaide, South Austr...
Looks like the cold anomaly in the eastern Indian ocean is breaking up in that too.

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#1440958 - 11/11/2017 03:12 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: CoastalStorm22]
Mega Offline
Meteorological Motor Mouth

Registered: 03/02/2003
Posts: 6623
Loc: Maryborough, Wide Bay, QLD
Originally Posted By: CoastalStorm22
Anyone know why NOAA measure AO at 1000mb but the SAM at 700mb?


Really good question, would love to know the answer to that as well. Probably worth hitting one of the pros up on twitter I reckon.

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#1440959 - 11/11/2017 06:36 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
mammatus meestrus Offline
Cloud Gazer

Registered: 20/11/2008
Posts: 40
Loc: lennox head
Stream showers all week with cool and cloudy conditions, 150mm already for November (Ballina) after record rainfall in Oct.
A synoptic chart that looks profoundly La Nina-ish.
Warm water surrounding the maritime continent.

Whether BOM eventually raises the flag on La Nina this wet signal has already been quite profound for eastern Australia, and the NAM hasn't even started yet.

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#1440960 - 11/11/2017 07:54 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Locke Offline
Weatherzone Addict

Registered: 27/12/2007
Posts: 4361
Loc: Brisbane
Starting to look pretty warm in the subsurface in the West.
_________________________
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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#1440966 - 11/11/2017 09:40 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: mammatus meestrus]
Kino Offline
Weatherzone Addict

Registered: 10/08/2017
Posts: 1269
Loc: Wollongong, NSW, Aus
Originally Posted By: mammatus meestrus
Stream showers all week with cool and cloudy conditions, 150mm already for November (Ballina) after record rainfall in Oct.
A synoptic chart that looks profoundly La Nina-ish.
Warm water surrounding the maritime continent.

Whether BOM eventually raises the flag on La Nina this wet signal has already been quite profound for eastern Australia, and the NAM hasn't even started yet.



Agree. Hopefully it deepens because we could well have a wet, cool day warm night summer ahead.

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#1440969 - 11/11/2017 10:17 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Chris Stumer Offline
Weatherzone Addict

Registered: 28/01/2010
Posts: 1611
Loc: Kingaroy
Cold water in the east and warm water in the west in the subsurface is a classic La Nina signal. Let's hope it keeps it up.

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#1440972 - 11/11/2017 11:05 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Mike Hauber Offline
Weatherzone Addict

Registered: 13/07/2007
Posts: 2757
Loc: Buderim
Warm subsurface expanding steadily towards the east following a recent westerly wind burst probably means a warm kelvin wave.



A similar Kelvin wave in 2007 during a strong La Nina persisted and caused weak warming for several weeks despite being followed up by nearly 4 weeks of trade winds significantly stronger than anything we have seen so far this year.

Previously I had speculated that there might have been a shift in the North Pacific with the NE looking more La Nina like and the NW looking more El Nino like. But I think that has largely reversed, and it looks like we are back to the previous pattern.

The SW Pacific has been quiet for the last few months, after being a substantial contributor to the warming pattern earlier in the year. As tropical convection heads back to the SH it seems that the SW Pacific is starting to wake up, and it looks pretty similar to what we saw earlier in the year so far. The recent WWB was pinned largely by a low pressure system well east in the coral sea, in contrast to lows in the NH which caused westerlies only briefly as they moved north and east. Westerly anomalies forecast in days 7-14 are chopping and changing a lot, but have been featuring low pressure systems well east, suggesting that as SH monsoon season ramps up WWB activity will also increase.

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#1440978 - 11/11/2017 12:35 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Chris Stumer Offline
Weatherzone Addict

Registered: 28/01/2010
Posts: 1611
Loc: Kingaroy
We could get a reflected Rossby Wave which could trigger more cooling. The trades are still looking healthy and another trade burst is predicted in early December.

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#1440980 - 11/11/2017 13:12 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: Mike Hauber]
Kino Offline
Weatherzone Addict

Registered: 10/08/2017
Posts: 1269
Loc: Wollongong, NSW, Aus
Originally Posted By: Mike Hauber
The SW Pacific has been quiet for the last few months, after being a substantial contributor to the warming pattern earlier in the year. As tropical convection heads back to the SH it seems that the SW Pacific is starting to wake up, and it looks pretty similar to what we saw earlier in the year so far. The recent WWB was pinned largely by a low pressure system well east in the coral sea, in contrast to lows in the NH which caused westerlies only briefly as they moved north and east. Westerly anomalies forecast in days 7-14 are chopping and changing a lot, but have been featuring low pressure systems well east, suggesting that as SH monsoon season ramps up WWB activity will also increase.


Can you explain how the SW Pacific will reverse the cooling tend? Surely in La Niña / cool neutral years that’s where you’d expect activity to be rather than eastern Pacific?

And given models keep chopping & changing, then surely you’d go with status quo which is cooling tend / trade winds?

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#1441002 - 11/11/2017 19:32 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: Kino]
Mike Hauber Offline
Weatherzone Addict

Registered: 13/07/2007
Posts: 2757
Loc: Buderim
Originally Posted By: Kino


Can you explain how the SW Pacific will reverse the cooling tend? Surely in La Niña / cool neutral years that’s where you’d expect activity to be rather than eastern Pacific?


A proper La Nina has the cool water a much further west which helps pin the cyclones/low pressure systems close to the coast, limiting the westerly activity associated with the Coral Sea cyclone season. Currently warm water extends further east, so there is the potential for systems to form further east and create more extensive westerly wind bursts.

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#1441011 - 11/11/2017 21:30 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 7166
Loc: Adelaide Hills.
#1440560:
One thing that can be required for rain is a mechanism to drive temperatures down and lapse-rates up. Which means whatever happens with whatever phase of the MJO, cloud-formation increases. Applies to a lot of features in weather systems.

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#1441012 - 11/11/2017 23:10 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: Mega]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 7166
Loc: Adelaide Hills.
Originally Posted By: Mega
Originally Posted By: CoastalStorm22
Anyone know why NOAA measure AO at 1000mb but the SAM at 700mb?


Really good question, would love to know the answer to that as well. Probably worth hitting one of the pros up on twitter I reckon.

The AAO/AO - Southern/Northern Hemisphere - would be based on SLP, so it would be nearer to the 1000 mb level. I think the SAM 700 mb is based on an Empirical Orthogonal Function or Principle Component Analysis from memory. I have not investigated either function/method to a great extent. There are clearly differences otherwise two different pressure levels would not be involved.

There are definitely different index versions for measuring similar phenomena.


Edited by Seira (11/11/2017 23:17)

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#1441028 - 12/11/2017 17:24 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Kino Offline
Weatherzone Addict

Registered: 10/08/2017
Posts: 1269
Loc: Wollongong, NSW, Aus
Looking better and better - those eastern cold anomalies are growing and pushing west. SST's in key areas around Aus are also improving.



CFS showing that this event is only just started, with some petrol in the tank



Edited by Kino (12/11/2017 17:25)

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#1441032 - 12/11/2017 18:41 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Petros Offline
Meteorological Motor Mouth

Registered: 30/12/2002
Posts: 6599
Loc: Maffra, Central Gippsland, Vi...
smile ...hopefully a benign fire season ahead for Victoria.

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#1441035 - 12/11/2017 19:56 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Chris Stumer Offline
Weatherzone Addict

Registered: 28/01/2010
Posts: 1611
Loc: Kingaroy
The 1949 to 1951 La Nina didn't really get going until December of 1949. The PDO looks to be going negative too.

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#1441036 - 12/11/2017 20:42 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
CoastalStorm22 Offline
Weatherzone Addict

Registered: 10/07/2006
Posts: 2703
Loc: Lane Cove, Sydney, NSW
Latest POAMA shows a drier than normal summer(Especially down the coastline) for most of EAUS from the gulf right down into NSW, looking at 2016 in comparison at this time and they look freakishly similar. I'm not yet convinced that La Nina = wet summer.


Edited by CoastalStorm22 (12/11/2017 20:45)

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#1441038 - 12/11/2017 20:52 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: CoastalStorm22]
Kino Offline
Weatherzone Addict

Registered: 10/08/2017
Posts: 1269
Loc: Wollongong, NSW, Aus
Originally Posted By: CoastalStorm22
Latest POAMA shows a drier than normal summer(Especially down the coastline) for most of EAUS from the gulf right down into NSW, looking at 2016 in comparison at this time and they look freakishly similar. I'm not yet convinced that La Nina = wet summer.


CFS doesn’t agree


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#1441040 - 12/11/2017 21:12 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Mega Offline
Meteorological Motor Mouth

Registered: 03/02/2003
Posts: 6623
Loc: Maryborough, Wide Bay, QLD
For what it's worth, November UKMET looks very wet right down the eastern seaboard for summer while EC looks about average to slightly above.

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#1441043 - 12/11/2017 22:11 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Mega Offline
Meteorological Motor Mouth

Registered: 03/02/2003
Posts: 6623
Loc: Maryborough, Wide Bay, QLD
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.



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#1441045 - 13/11/2017 01:05 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Chris Stumer Offline
Weatherzone Addict

Registered: 28/01/2010
Posts: 1611
Loc: Kingaroy
The summer of 2016 was largely due to the positive SAM and the lingering effects of the 2015/2016 El Nino. POAMA are only going for cool neutral which is why it's predicting a dry summer.

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