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#1470690 - 13/09/2018 13:10 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Funkyseefunkydo Offline
Weather Freak

Registered: 30/04/2007
Posts: 657
Loc: East Lake Macquarie
About 98% of the time it blows easterly.

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#1470691 - 13/09/2018 13:19 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Petros Offline
Meteorological Motor Mouth

Registered: 30/12/2002
Posts: 7235
Loc: Maffra, Central Gippsland, Vi...
Honestly didnt know that WWB's are so rare.

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#1470692 - 13/09/2018 13:51 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Mike Hauber Offline
Weatherzone Addict

Registered: 13/07/2007
Posts: 3200
Loc: Buderim


This image shows both actuals and anomalies over time. WWBs primarily occur in the far west, and are associated with actual westerly winds, and have been happening regularly this year. Average winds in the far west are pretty close to neutral and actuals and anomalies are fairly similar. For much of the rest of the Pacific average winds are strong easterlies, so for most of this year there have been strong easterlies, and a mix of weak easterly and westerly anomalies.

Of note is the event in June. No actual westerlies occurred, but some moderate anomalies further east near the dateline. This corresponds to an area of substantially weaker easterlies. The strongest westerly wind bursts in 97/98 were able to turn winds westerly in this region, with actual westerly winds getting past 160W but generally in most el ninos actual westerlies are mostly limited to west of 180.

This is the impact of the westerly activity so far:



Substantial Kelvin wave activity and subsurface warming was initiated by the westerly activity around Feb-Apr, and again in the last couple of months. When the subsurface warming reached the east coast, substantial surface warming in the east followed. A lul in Westerly activity in June combined with some slight enhancement of trades in July resulted in a cool Kelvin wave which reached the east coast in late August and resulted in recent cooling. The new subsurface warming is raising subsurface temps to significantly past the activity earlier in the year, and I expect will warm the surface significantly further than the earlier surface warming.

Recall that models had forecast winds to switch to generally westerly (anomalies) from August in the western region, and this seems to have occurred, and would seem likely to continue due to the substantially elevated SST temps in this region.

I'd say odds of a genuine el nino are now getting quite high, maybe 80-90%.

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#1470694 - 13/09/2018 14:48 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: Petros]
ColdFront Offline
Meteorological Motor Mouth

Registered: 29/06/2008
Posts: 18443
Loc: Burnett Heads
Originally Posted By: Petros
Honestly didnt know that WWB's are so rare.


Most of the time the winds remain easterly in the Eastern pacific along the equator but weaken with the bursts. In El Nino the walker circulation changes and westerly winds penetrate out into the pacific much further towards the east. Easterlies usually continue in a weakened state off the South American coast.

HERE is perhaps the best example via diagrams as it shows the relative wind speeds with bolder / thinner lines.

*Note where the westerlies are in LaNina.

https://www.climate.gov/news-features/blogs/enso/walker-circulation-ensos-atmospheric-buddy
_________________________
"When it comes to the weather, "occasionally" is better than "not at all".

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#1470703 - 13/09/2018 18:34 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
ColdFront Offline
Meteorological Motor Mouth

Registered: 29/06/2008
Posts: 18443
Loc: Burnett Heads
_________________________
"When it comes to the weather, "occasionally" is better than "not at all".

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#1470786 - 15/09/2018 14:15 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
RC Offline
Weatherzone Addict

Registered: 29/09/2007
Posts: 2312
Loc: near Rockhampton, Qld
Nino 1+2 is showing a large rise in anomaly temperatures, will 3.4 follow suit in a couple of weeks?

It looks like that anomalous warm pool might be finally breaking to the surface.

Still odd that after the super El Nino of a few years ago, we are still stuck in a warm El Nino like weather. While last year was borderline La Nina, if at all, there were not much La Nina type weather events.

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#1470815 - 15/09/2018 18:47 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Petros Offline
Meteorological Motor Mouth

Registered: 30/12/2002
Posts: 7235
Loc: Maffra, Central Gippsland, Vi...
RC - if you are correct, that warm pool going up against a hefty surface trend atm:



....indicators are still showing neutral for weeks ahead to this tiro.

Regardless of anomolies etc... - heres what a look outside the window tells us for Aus right now:



Warm pools, upper or lower, WWB's, whatever. If the surface synoptics allow, there's adequate moisture from Australias "normal sources" to provide spring rain over coming weeks IMO.


Edited by Petros (15/09/2018 18:55)

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#1470817 - 15/09/2018 19:12 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
ashestoashes Offline
Weather Freak

Registered: 22/10/2017
Posts: 401
Loc: Voyager Point (South West Sydn...
Synoptics should start lining up as we should fall to a negative sam I'm just hoping that 500mb height anomalies continue with strength up to NT that will really tap into moisture.


Edited by ashestoashes (15/09/2018 19:15)

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#1470828 - 15/09/2018 22:09 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Chris Stumer Offline
Weatherzone Addict

Registered: 28/01/2010
Posts: 1804
Loc: Kingaroy
A negative SAM in late spring and summer brings an increase in heatwave as westerly winds push hot and dry desert air eastwards which will create nasty bushfire conditions.

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#1470834 - 15/09/2018 23:23 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Kino Offline
Weatherzone Addict

Registered: 10/08/2017
Posts: 2426
Loc: Wollongong, NSW, Aus
Sept is hardly late spring though. If that were November then different story.

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#1470842 - 16/09/2018 11:15 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ashestoashes]
Petros Offline
Meteorological Motor Mouth

Registered: 30/12/2002
Posts: 7235
Loc: Maffra, Central Gippsland, Vi...
Originally Posted By: ashestoashes
Synoptics should start lining up as we should fall to a negative sam I'm just hoping that 500mb height anomalies continue with strength up to NT that will really tap into moisture.


AccG and EC are showing the high pressure due next weekend to be centered more along the Aus S coastline which supports the above.

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#1470844 - 16/09/2018 11:22 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
RC Offline
Weatherzone Addict

Registered: 29/09/2007
Posts: 2312
Loc: near Rockhampton, Qld
Negative SAM's do not help northern Australia though.

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#1470869 - 16/09/2018 22:17 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Kino Offline
Weatherzone Addict

Registered: 10/08/2017
Posts: 2426
Loc: Wollongong, NSW, Aus
But given northern Aus is still in their dry season, thatís not unexpected?

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#1470884 - 17/09/2018 18:40 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Petros Offline
Meteorological Motor Mouth

Registered: 30/12/2002
Posts: 7235
Loc: Maffra, Central Gippsland, Vi...
What is peoples opinion on the present state of play out in the Pacific?

......WWB's, WWB anomolies, trade winds weaker (...or stronger)?

I thinks its all a hotch potch - and indecipherable for models at present.

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#1470888 - 17/09/2018 20:26 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
CoastalStorm22 Offline
Weatherzone Addict

Registered: 10/07/2006
Posts: 2817
Loc: Lane Cove, Sydney, NSW
Latest weekly IOD has skyrocketed into positive territory coming in at +0.85!

Looks like that positive event is coming to fruition.
_________________________
Lane Cove Weather - WU

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#1470889 - 17/09/2018 20:58 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: Kino]
RC Offline
Weatherzone Addict

Registered: 29/09/2007
Posts: 2312
Loc: near Rockhampton, Qld
Originally Posted By: Kino
But given northern Aus is still in their dry season, thatís not unexpected?


October is really the start of wetter conditions though.

August, September are the two driest months, at least for CQ region.

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#1470890 - 17/09/2018 21:10 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
ashestoashes Offline
Weather Freak

Registered: 22/10/2017
Posts: 401
Loc: Voyager Point (South West Sydn...
In a turn of events though Nino 3.4 has dropped to a negative level.

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#1470891 - 17/09/2018 21:24 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
RC Offline
Weatherzone Addict

Registered: 29/09/2007
Posts: 2312
Loc: near Rockhampton, Qld
Temporarily. When you look at an animation you can see how it all travels in waves, so it all oscillates up and down all the time.

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#1470898 - Yesterday at 09:32 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Mike Hauber Offline
Weatherzone Addict

Registered: 13/07/2007
Posts: 3200
Loc: Buderim
Depth averaged temperature (to 300m) of equatorial Pacific in September, and peak nino 3.4, for selected years (including to March following year):

1982 0.44, 2.43
1986 0.24, 1.23
1987 -0.18, 1.53
1991 0.34, 1.62
1994 0.11, 1.21
1997 0.67, 2.42
2002 0.51, 1.41
2006 0.39, 1.10
2009 0.39, 1.81
2014 0.38, 0.89
2015 0.70, 2.57
2018 0.60, ???

While the subsurface build up of heat is moderate rather than extreme in the east, it is quite extensive, spreading a long way west, and also north and south, and so it is the third strongest build up of equatorial heat after 1997 and 2015.

MJO is forecast to emerge with some strength towards Atlantic/Africa. Could boost westerly winds in the eastern pacific making for some dramatic warming as the subsurface heat looks like it is also starting to make its presence felt. Will then be interesting to see if the MJO continues with some strength into the Indian Ocean, which would put a significant damper on the developing el nino.


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#1470903 - Yesterday at 12:16 Re: Climate Driver Discussion 2018 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
RC Offline
Weatherzone Addict

Registered: 29/09/2007
Posts: 2312
Loc: near Rockhampton, Qld
But really it was supposed to be in El Nino by now.

I do not know if it is getting harder to predict ENSO or it was always this unreliable.

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