Technical Current & Forecast Climate Drivers

POW Hungry

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MJO looks to be sustained strong through the IO at this point. Sure, a downgrade from the 3.5, but still oververifiying against that EC LR outlook.
rmm.phase.Last40days.gif
Looks like GFS going for an overtaking signal to return to the Western IO over the next week:
gfs_chi200_global_9.png
 

Hermon

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Quite a significant shift in the BOM climate forecast released yesterday. Potentially decent precip over inland Australia and Murray Basin this winter.

ENSO wrap comes out tomorrow and I suspect the IOD forecast might've shifted as well.
 

Michael Hauber

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Trade surge as the MJO moves through the Indian sector well underway and is putting a break on the warming trend:

surface.png


The recent WWB appears to have generated another warm kevlin wave. It does seem to be too close to the previous kelvin wave to allow it to properly surface
subsurface.png


Previous forecasts had suggested a quick MJO passage through the Indian and Australian sectors. Movement to date has been quite rapid, but now there is suddenly a bit of a stall forecast:

ensplume_full (9).gif


Two weeks ago (27th Apr) I posted a forecast showing westerly winds starting up again in the west at the end of the two week forecast. Current forecasts look quite similar with westerly winds starting up again near the end of the two week forecast. The forecast from two weeks ago had only week easterly anomalies but now we are looking at stronger easterly anomalies. Of interest also is some strong anomalies forecast in the Indian Ocean. . I recall a burst of strong activity in the Indian Ocean about this time of year that caused cooling near Australia and seemed to kill the possibility of a potential -ve IOD last year. This activity is further west more central to west Indian. Not sure what impact it will have - I see the IOD driven by SSTs in the east with the SSTs further west more a symptom than a driver.

u.anom.30.5S-5N (9).gif


Chances of an el nino have receded with this extension to the current period of enhanced trades. Neutral looks quite likely now to me. Maybe if the current activity can extend further a definite cool neutral and chance at la nina may emerge.
 

snowbarbie

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..as noted forecast westerly wind bursts out at two weeks again. Up until recently it did look like at least weakish westerlies might have held out in the west, but apart from the isolated & fairly weak pocket there now, the trades look set to crash the party. If gfs keeps throwing up wwbs at the end of forecast runs...the odds have to improve that something will finally click...
 
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Michael Hauber

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Indian Ocean activity causing an extension to the trade surge seems to correspond to some quite warm SSTs in the northern Indian Ocean. These SSTs are noticeably warmer than SSTs in Pacific (both by anomaly and by absolute temps).

cdas-sflux_ssta_global_1 (2).png


This activity culminates in a significant cyclone forecast to move along the west coast of India and impact Pakistan. EC Wed 6pm:

EC Wed 6pm.PNG


The warmest SSTs are more to the east of India, and this cyclone as forecast would cause cooling more to the west.

One thing I don't like about the Indian Ocean SSTs is that they are warmer to the north than south. An important part of IOD dynamics is the north-south temp gradient with warm temps to the north promoting stronger southerly wind and cooling in the south. There were some fairly solid cool SSTs in SE Indian following late SH cyclone activity off WA but these cool anomalies have eased a lot in the last few weeks.
 

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Michael Hauber

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The activity in the west Indian Ocean has resulted in some fairly strong cooling. Seven day SST change:

7 day sst change.PNG


Current SST anomalies maintain very warm SSTs in NE Indian. The North South temperature gradient I was concerned about seems to have eased a little with similar SSTs in SE Indian (at least close to North WA, still cooler further out). Also note that the NE Pacific SSTs are still a bit warmer than west Pacific, but not a large gap.

current anomaly sst.PNG


Current forecasts suggest a similar level of activity in the NE Indian to what we saw in the NW Indian, so I would expect a week from now we will see a similar level of cooling in the NE. This might leave us with a good N-S temp gradient, and also a decent E-W gradient, possibly putting in place a -ve IOD event.

At the same time the cooling in the NE Indian may shift the balance of warmest SSTs towards the Pacific supporting a forecast move of the MJO into the Pacific:

ensplume_full (7).gif


It seems to me at the moment that the MJO is making strong alternating pushes towards warm and cool at the moment, suggesting neutral. What could happen though is if the MJO goes weak then whichever phase had the most recent push towards warm or cool may have a more lasting impact, even if only to several months of definite cool neutral or warm neutral.
 
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POW Hungry

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What implications if any will the upcoming BOB cyclone have on any potential -IOD?
For Yaas?
Very little IMO.

Core winds to 45-65knts. Be all over by tomorrow. If it lingered any more than a few days it might be worth taking a closer look.
BoB sits between the two indexed regions of IOD anyway.
If it was in the Arabian Sea like Tauktae was then it'd likely influence some SST change.
 

Spiral

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#1008
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The storm tracked to the eastern side of the Arabian sea. There was of course cool upwelling along its path. But it did not cool the whole Arabian sea.
Storms only cool a limited area along their path and the warmer water will start mixing back in not too many days after. Never will a cyclone cool the whole sea.
 
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Nature's Fury

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Is anyone able to explain the difference between the Interdecadal Pacific Oscillation (IPO), Pacific Decadal Oscillation (PDO) and ENSO cycles? I'm also interested to know how these long-term IPO/PDO trends work compared to short-term ENSO. I would have thought if there was a warming or cooling trend in the Pacific over decades that would translate to more or less corresponding warm or cool ENSO events during that time, but ENSO events appear to have the same regularity regardless. This article makes some interesting points, but doesn't really explain any of these questions:

https://www.news.com.au/technology/...e/news-story/ad0399796fbc8f2c311cfd87466c16a0
 
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Jellybeans

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Is anyone able to explain the difference between the Interdecadal Pacific Oscillation (IPO), Pacific Decadal Oscillation (PDO) and ENSO cycles? I'm also interested to know how these long-term IPO/PDO trends work compared to short-term ENSO. I would have thought if there was a warming or cooling trend in the Pacific over decades that would translate to more or less corresponding warm or cool ENSO events during that time, but ENSO events appear to have the same regularity regardless. This article makes some interesting points, but doesn't really explain any of these questions:

https://www.news.com.au/technology/...e/news-story/ad0399796fbc8f2c311cfd87466c16a0
They are all SSTA indexes for certain regions of the Pacific, at least on a basic level.

ENSO:
Unknown.png


PDO:
PDO-pattern.png


IPO (Difference btwn 1/3 and 2)
maptpiipo.sm.png
 

Michael Hauber

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The surface conditions show that temps have been quite close to neutral with no significant anomalies either positive or negative since mid March. There has been a decent easterly wind surge in the last few weeks, and it is intriguing to compare to the surge in October which was not a lot stronger (except in the far west) but seemed to cause some quite significant cooling.

surface.png


There seems to be some significant warm kelvin wave activity which may have been a warming influence which has cancelled out the initial cooling influence of the trade surge. However it seems likely that there may be a cool Kelvin wave to come following the strong switch from west to east anomalies.

subsurface.png


Previously I mentioned that if the MJO became weak then whichever was the last phase may have a lasting influence, and it appears that the MJO has collapsed just as it was approaching the warm favoring Pacific Sectors. In the shorter term the MJO is forecast to re-emerge in the Pacific sectors, but then weaken again after a short period. Forecasts generally seem confusing with different models showing different things after the short term re-emergence in the Pacific.

EMON_phase_MANOM_51m_full.gif


The activity in the bay of Bengal has caused quite a lot of cooling. We did have a warm north to cool south gradient, but now this has reversed with warmer in the south. But overall a weak gradient. There is a strong gradient from warm east to cool west in the Indian, but I see E-W as being more symptomatic and N-S as being the key driver of IOD variability. Definitely looks more on the cool side favorable to Australia though. Of concern is tropical activity forecast in the SH with a weak tropical low possibly reaching the NW Australia coast in June. This could cause some cooling in SE Indian.

Its also interesting to see strong warm anomalies in the Pacific a fair way north. Might be some significant tropical activity in the NW Pacific, but possibly further north blunting the amount of westerly winds triggered along the equator.

cdas-sflux_ssta_global_1 (3).png
 
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snowbarbie

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As I imagine an upwelling KW would look heading east to at least partially erode earlier KW warming


Notice that there are still wwb's forecast in the period ahead
GFS Sunday June6 00z, 21 knots on the crosshairs


but must be worth asking how many priming shots can be left in the locker? how depleted is the wpwp?
 
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snowbarbie

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While 3.4 has been trending gradually upwards, modest cool anoms have been persistent in far east, perhaps longer than expected?

Seen this described elsewhere as the effect of arriving KW's squeezing the remnants of an existing cooler water out ahead & up to the surface like a bulldozer, but I thought perhaps there is an element of additional upwelling been driven by low level northerly winds close in along the Peruvian coast.

Cooler water would then feed into the anomalous north-west drift.



Interesting with the equatorial surface current which was dominated by eastwards anomalous drift in April seems to have been pretty much stopped and even reversed for this month.

Anything to the thought that the system of equatorial currents shifting slightly northwards of mean position, having some influence?
 

Dylan Kearney

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I thought this may be the best place to post this, if not please let me know. :)
I was just scrolling through the EC 500hpa wind chart on windy for this coming Saturday and noticed that the jet stream stretches from the upper low over the Tasman Sea, nearly to Madagascar without interruption. Is this unusual?

BC3DC943-113E-4EAA-95FD-6B9E0B3EBC8B.png


E67B6811-F931-4606-AA0C-CF9EF081A80B.png
 

snowbarbie

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  • 30 day moving Soi drops to <0 first in awhile more decisive atmospheric response underway?
  • warming in far east consolidates and patchy weak westerly anoms set to persist
  • daily 3.4 upward trend steepens
last window on the boy-child awaiting mjo miracle?
 

Craig B

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If I'm reading it correctly from the source proving the chart below https://www.esr.org/research/oscar/equatorial-pacific-conditions/
....the boy-child's moment may have already gone
An interesting effort at enso prediction - I think it's saying a double dip nina, at least a bit on the cooler side than neutral coming up...but check out the link and decide fr yourself...

sc_sst_eof_3yr.png
Very interesting, thanks for the link!

And you are reading correctly. A westward sea surface current anomaly usually precedes warming, and movement towards La Nîna.
 

Michael Hauber

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Despite mediocre westerly activity as the MJO went through its Pacific phases, the warming trend seems to have continued. Westerly activity seems to be generally weaker than the preceding easterly surge.

surface.png


I suspect that a good part of this warming is due to the recent warm kelvin wave reaching the eastern edge of the Pacific. There is clearly a cool kelvin wave in progress, which would account for the easterly current anomalies that snowbarbie has noted. Unfortunately there are still weak warm anomalies in the subsurface in the west, and not that far west, already extending further east than the dateline. The subsurface could easily support further warm kelvin wave activity if westerly activity occurs.


subsurface.png


The MJO has had a weak pass through the Pacific sectors and is approaching the la nina friendly Indian Ocean sectors, likely to enter in the next couple of days. However forecasts suggest the MJO will become weak and confused and maybe even backtrack away from the Indian.

ensplume_full (10).gif


Satellite SSTs still show some cool anomalies in the central Pacific, so not much push on the atmosphere for convection to move further east away from maritime continent. Cool spot just north of PNG is concerning - see if it gets bigger to set up a significant cool west to warm east temp gradient which would tend to enhance westerly activity.

ssta.daily.current (1).png


Currently nino areas have warmed, whereas the IOD has been cool for a couple weeks. Latest weekly BOM:

nino 3: +0.23
nino 3.4 +0.21
nino 4 + 0.18
IOD -0.5

If the warming trend in nino indices continues then we would be easily getting to weak el nino territory later in Spring. However all models seem to be going for cool ENSO conditions, although probably not strong enough to qualify as La Nina.

In the Indian Ocean the cooling in Bay Of Bengal reversed and there are warm SSTs there again - but not nearly as warm as they were roughly a month or so ago. Cool anomalies continue in the far NW. Current wind patterns show an area of doldrums to the west of Indonesia, which is allowing for SSTs to warm up in the sun and very strong W-SW winds in the NW Indian which is causing evaporative cooling, and also upwelling off the coast due to Ekman effects.

EC Tue 3pm.PNG


It seems that the SH trade winds are being pushed around the area of doldrums in the east and funnelled into the NW. Not sure why this is happening. Maybe there is a direct impact of warm SSTs in the east causing rising air and low pressure, but there is not much a precipitation or cloudiness signature associated with this region (which would also cause some cooling). Maybe this does relate to the IOD SST signature with IOD index at -0.5, in which case we could be close to -ve IOD being self-reinforcing. Could be due to lower than usual SLPs over land in middle east and south Asia. I've often wondered whether land can have anything like an SST anomaly type impact either through increased soil temps, or variations in soil moisture levels. Or changes in pollution from heavily populated regions. Scientific literature has documented the brown ocean effect where rain over hot land ahead of a tropical cyclone/hurricane can act to sustain the system over land similar to warm SSTs. Trivia - the land heat content is is much lower than water on a weight for weight basis, but closer to 50% on a volume basis as rock/soil is much denser. However if the top 50 meters of the ocean is warm, and there is low pressure and cloudy/rainy conditions it is much harder to cool SST surface as the heat can easily mix through the top 50 meters of ocean. Whereas on land the heat can only quickly mix to much less than a meter.
 
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