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#1446410 - 30/12/2017 23:05 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Mega Offline
Meteorological Motor Mouth

Registered: 03/02/2003
Posts: 7016
Loc: Maryborough, Wide Bay, QLD
Speaking of tropical moisture - just look at QLD's next trough system - no shortage of moisture there, and streamlines all show this humid N'ly flow coming down from the tropics. In an El-Nino that area is usually very dry so down here you'd more often than not end up with endless dry heat and no storms with such troughs.


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#1446411 - 30/12/2017 23:12 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Long Road Home Offline
Meteorological Motor Mouth

Registered: 08/10/2007
Posts: 8520
Loc: Northern Beaches Syd
Agreed with Kino and John. Extra moisture associated with the tropical low with a NW cloudband dropping significant rain in SE AUS and hundreds more over inland WA. Why extra moisture? Because higher SSTs nearby and around the country. Why higher SSTs? Because La nina. Simple logic there, you could argue whether you believe it's attributed or not til the cows come home, but is it not fair to say that the excess moisture and rainfall aremore likely than not caused by La Nina?

If we bring the IOD into the picture, what helps a negative IOD come about? La Nina.

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#1446412 - 30/12/2017 23:15 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
GringosRain Offline
Weatherzone Addict

Registered: 19/06/2007
Posts: 1576
Loc: Quorrobolong NSW
You need to read posts more carefully. I didnt say there was an El nino or -IOD. I said you could look at years with that combo and it would likely show the pattern of rainfall anomalies you are seeing now and it doesnt matter what the ENSO state is....when there is active NW moisture Victoria is likely to benefit.

You said "Moisture across the continent" as if to suggest that moisture across the continent generally never has anything to do with IOD and El nino.....thus my response.

If you are actually saying " the current moisture" across the continent has been contributed to by La nina, I wont disagree entirely, but it just looks like standard enhanced convective activity in warm water to the NW of continent with good shear environment. The trades are only just picking up across that area anyway and were fairly benign in the lead up to cyclone formation werent they? Im just saying the Indian Ocean looks to be playing a bigger role in moisture availability to the east of the continent as it also did across the winter and spring season.

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#1446416 - 30/12/2017 23:26 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: Long Road Home]
Mega Offline
Meteorological Motor Mouth

Registered: 03/02/2003
Posts: 7016
Loc: Maryborough, Wide Bay, QLD
Originally Posted By: Long Road Home
The way systems position themselves and utilise the moisture is an important aspect, as it dictates where gets what and when.


Don't know why you deleted this from your post but I think that's a great analysis, you're spot on there imo. That's why it annoys me seeing trough after trough amplify in the east Tasman Sea because it usually leaves us ridged in with no real triggers to help tap into that moisture from the tropics. Seems like such a waste of water when it happens so often.

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#1446417 - 30/12/2017 23:33 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: Mega]
Kino Offline
Weatherzone Addict

Registered: 10/08/2017
Posts: 2263
Loc: Wollongong, NSW, Aus
Originally Posted By: Mega
Originally Posted By: Long Road Home
The way systems position themselves and utilise the moisture is an important aspect, as it dictates where gets what and when.


Don't know why you deleted this from your post but I think that's a great analysis, you're spot on there imo. That's why it annoys me seeing trough after trough amplify in the east Tasman Sea because it usually leaves us ridged in with no real triggers to help tap into that moisture from the tropics. Seems like such a waste of water when it happens so often.


Thoroughly agree; the nuances associated with the various climate drivers!

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#1446418 - 30/12/2017 23:35 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Long Road Home Offline
Meteorological Motor Mouth

Registered: 08/10/2007
Posts: 8520
Loc: Northern Beaches Syd
lol I was gonna leave it there, but thought my main paragraph was enough. Anyway, glad you plucked that part out.

Anyway EC has this shift in pattern happening toward the end of the run with a broad inland trough and highs back south again. Whether it'll be a swift or slow shift is to be seen.

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#1446419 - 30/12/2017 23:39 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: Long Road Home]
Kino Offline
Weatherzone Addict

Registered: 10/08/2017
Posts: 2263
Loc: Wollongong, NSW, Aus
Originally Posted By: Long Road Home
lol I was gonna leave it there, but thought my main paragraph was enough. Anyway, glad you plucked that part out.

Anyway EC has this shift in pattern happening toward the end of the run with a broad inland trough and highs back south again. Whether it'll be a swift or slow shift is to be seen.


EC also pegged monsoon incursion next week so that effect should flow down ~ 2 weeks later if it happens.

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#1446420 - 30/12/2017 23:39 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: Mega]
ColdFront Offline
Meteorological Motor Mouth

Registered: 29/06/2008
Posts: 18406
Loc: Burnett Heads
Originally Posted By: Mega
Originally Posted By: Long Road Home
The way systems position themselves and utilise the moisture is an important aspect, as it dictates where gets what and when.


Don't know why you deleted this from your post but I think that's a great analysis, you're spot on there imo. That's why it annoys me seeing trough after trough amplify in the east Tasman Sea because it usually leaves us ridged in with no real triggers to help tap into that moisture from the tropics. Seems like such a waste of water when it happens so often.


Yes, spot on. When people debate why the south east of the country has had plenty and the nth east tropics have had none it is due to this very fact. The ridge on the east coast has sent moisture down the centre out of the tropics into the sth east of the country. It's not rocket science.
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#1446421 - 30/12/2017 23:40 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
gazzatsv Offline
Weather Freak

Registered: 19/03/2011
Posts: 661
Loc: Townsville
The Ssts over the NW are nothing remarkable and not why there was a cyclone, not had anything to do with LaNina. If you want to look at high Ssts look at the Gulf but nothing coming from there. Not saying that there isnít a La NiŮa but I think you are all overplaying itís effects that is for sure.

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#1446422 - 30/12/2017 23:42 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Long Road Home Offline
Meteorological Motor Mouth

Registered: 08/10/2007
Posts: 8520
Loc: Northern Beaches Syd
gazza, that's because there are no disturbances in the Gulf, if there was it'd explode overnight. Once the monsoon kicks in, you'll have disturbances all along it delivering massive widespread falls across the north. It all comes down to where they form exactly. I've never seen SSTs this high go to waste, from experience somewhere gets hammered in the end.

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#1446427 - 31/12/2017 00:07 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: GringosRain]
Thunderstruck Offline
Lightning man

Registered: 10/05/2001
Posts: 14938
Loc: Seaford Meadows, SA
Originally Posted By: GringosRain
Originally Posted By: _Johnno_
La Nina having very little impact.. As record breaking rainfall continues to fall over parts of Victoria and southern NSW

First link Vic 24 hours rainfall

http://www.bom.gov.au/jsp/awap/rain/inde...d=daily&area=vc

Second link NSW 24 hour rainfall

Third link rainfall month to date for Victoria spot falls of 400-600mm ranges north east of Melbourne in 30 days!

http://www.bom.gov.au/jsp/awap/rain/inde...=cmonth&area=vc

Fourth link rainfall month to date for NSW southern galf of the state 3-6 times more than the average normally for December

http://www.bom.gov.au/jsp/awap/rain/inde...=cmonth&area=ns

Fifth link rainfall anomalies for Dec so far NSW

http://www.bom.gov.au/jsp/awap/rain/inde...=cmonth&area=ns

Sixth link rainfall anomalies so far for December for Victoria with spot falls close to 400mm above normal north east of Melbourne

http://www.bom.gov.au/jsp/awap/rain/inde...=cmonth&area=vc

But sure this La Nina is having minimal or no impact. One bad month in parts of Queensland and some people come to this conclusion... Um ok. It is possible there are other factors at play here but it sure isn't La Nina or lack of it. Could it be possible its where the bulk of the troughing and upper troughing has peaked which has been south eastern Australia this month hence the exceptional rainfall? But with this you need moisture and there has been no shortage of it! The proof is in the pudding.

If you get one great month with exceptional rainfall somewhere in south eastern OZ of course you won't get a great month in your area and vice versa if QLD was wet Vic and southern NSW may be drier. How about we look at the 3 month rainfall deciles once December is over and get a bigger picture of what's really happening than just focus how dry it is the last few weeks in parts of QLD.







I dont see any of this as nina related. Victoria copping it is directly related to the blocking high that has been there for years now and the NW tropical feed, probably lingering effects -IOD (yes yes it doesnt count in summer) well it does and it is, because look where the moisture is coming from. The NW moisture is being triggered over the area right in the pointy spot for low pressure in this L shaped high blocking high right over that NE area of Vic. The wet winter down there was due to -SAM and NW moisture too. Look at all the cyclones off the NW coast one this week and long term GFS going for another 2 in the next 2 weeks. Yet there isnt a cloud in the coral sea.....sure its La Nina! Its all being driven from the NW moisture and a blocking high due to the positioning of the LWT...just like cold fronts post a page back.
I recon with the pressure systems as they are you could have full blown Nino and still be collecting rain like that which fell across Victoria recently.


Now this is not right.

Check back to 2016, record breaking rainfall across SA due to negative IOD and a co-operating SAM at the time of the infeeds. Significantly better than VIC did in spring and summer. NW feed meeting up with southern fronts peaking in the Bight and the Central SA region. Some help from pacific but minimal.

Fast forward to 2017 no negative IOD, closer to positive if anything but a developing La Nina and very warm SST's in the Tasman. NW moisture??? well where is my damn rain then in Adelaide!!!! cos I can tell you right now it aint coming from the NW this season, there has been absolutely sweet jack johnny coming from the NW and hence we are bloody dry. Many fronts have smashed Perth then dried out over SA without any supply only to magically and incredible erupt over the border into VIC and NSW. Why? SURFACE MOISTURE and bucketloads of it feeding in off the Tasman and the Coral, aided by those SST's. NW moisture has got bugger all to do with this season - that sort of moisture is usually middle and upper level....looks pretty on satpic but what's the good when it's dry as a nonger below 10,000ft.

TS cool

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#1446431 - 31/12/2017 00:53 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
_Johnno_ Offline
Weatherzone Addict

Registered: 08/11/2009
Posts: 1744
Yes spot on Thunderstuck.. Could not put that better myself.
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#1446449 - 31/12/2017 08:35 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: Thunderstruck]
GringosRain Offline
Weatherzone Addict

Registered: 19/06/2007
Posts: 1576
Loc: Quorrobolong NSW
Fair enough.....but if the blocking high was sitting 800ks further west, you would likely be getting that same peaking of fronts and a trigger over your region and it would be little to do with the pacific and your view might be different.
Its not like the NW is cold there is cooler water at 100W and warm water 120W so this would seem to be a nice setup for injecting moisture? Its just the trigger that is the key.

As I said in my earlier post is the Tasman heat anomalies due to La nina or is due to the blocking high? In which case if Victoria is benefiting from eastern moisture is it really La nina related or just a a helpful benefit of the blocking system causing high SST temps and triggers over the region...

The driver that embeds the LWT and creates these blocking systems is really what is paying up the rain. Im becoming less interested in other climate drivers and more interested in what creates the blocking systems, LWT nodes, Jet stream etc. I recon we could have cold temp anomalies off the east coast, but if we had HP systems sitting low in the tasman and long fetch easterlies blowing into cutoff cold pools we would get floods just the same as if you had warm water anomalies.

There is a load of atmospheric moisture up here too but it hasnt done anything yet due to the pressure systems and lack of triggers.

Anyway its not far off a proper change to what will obviously be a nina pattern so my agitating re what has been happening will change. N-hemisphere is super cold in Asia and US so this might also play a role in driving some serious events in a warm Australian region.

Happy New year!

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#1446472 - 31/12/2017 11:38 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Dawgggg Offline
Meteorological Motor Mouth

Registered: 25/03/2007
Posts: 23687
Loc: Townsville
I will be revisiting this thread in a few months just to talk about how the Monsoon failed again for NQ haha.

Got northerlies today, its 50% humidity.

Allllll that moisture....
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#1446473 - 31/12/2017 11:40 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Dawgggg Offline
Meteorological Motor Mouth

Registered: 25/03/2007
Posts: 23687
Loc: Townsville
22mm here for the month too, only 100mm behind average for the month.

This is the driest oct-dec period Ive seen. Sorry but I cant see a monumental shift in a weather pattern. You cant blame us either.


Edited by Dawgggg (31/12/2017 11:44)
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2015/16 Storms
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#1446477 - 31/12/2017 12:44 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
Petros Offline
Meteorological Motor Mouth

Registered: 30/12/2002
Posts: 7055
Loc: Maffra, Central Gippsland, Vi...
Hopefully the latest GFS run is correct in predicting troughier conditions for Qld towards the end of next week Trav.

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#1448259 - 10/01/2018 10:41 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: GringosRain]
Thunderstruck Offline
Lightning man

Registered: 10/05/2001
Posts: 14938
Loc: Seaford Meadows, SA
Originally Posted By: GringosRain
Fair enough.....but if the blocking high was sitting 800ks further west, you would likely be getting that same peaking of fronts and a trigger over your region and it would be little to do with the pacific and your view might be different.
Its not like the NW is cold there is cooler water at 100W and warm water 120W so this would seem to be a nice setup for injecting moisture? Its just the trigger that is the key.

As I said in my earlier post is the Tasman heat anomalies due to La nina or is due to the blocking high? In which case if Victoria is benefiting from eastern moisture is it really La nina related or just a a helpful benefit of the blocking system causing high SST temps and triggers over the region...

The driver that embeds the LWT and creates these blocking systems is really what is paying up the rain. Im becoming less interested in other climate drivers and more interested in what creates the blocking systems, LWT nodes, Jet stream etc. I recon we could have cold temp anomalies off the east coast, but if we had HP systems sitting low in the tasman and long fetch easterlies blowing into cutoff cold pools we would get floods just the same as if you had warm water anomalies.

There is a load of atmospheric moisture up here too but it hasnt done anything yet due to the pressure systems and lack of triggers.

Anyway its not far off a proper change to what will obviously be a nina pattern so my agitating re what has been happening will change. N-hemisphere is super cold in Asia and US so this might also play a role in driving some serious events in a warm Australian region.

Happy New year!


Doesn't work that way....if the blocking high was 800km further west we'd simply have even drier weather...with a stronger ridge than ever! Because the lay of the land will just re-shape the high, troughing will still form in the east as it always does in summer, it just might stop the pure NE/E feed into VIC as they would have more attempts at southerly and SE intrusions. In a nutshell we are simply too far west to benefit for significant NE infeeds of long duration, the only exception when we can maximise potential is during a very strong positive SAM, combined with very significant inland troughing PLUS a strong La Nina where the moisture does not dry out when it gets to us so we actually have a chance down here. But it doesn't take much for the Bight ridge to reform at the slightest hint of cooler air pushing up from the SW-S..and the trough/lifting mechanisms just shift 700-800km N whilst the coastal and growing regions of the state become more stable and drier again. This is our bread and butter in warmer months mate!!

TS cool


Edited by Thunderstruck (10/01/2018 10:43)

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#1448262 - 10/01/2018 11:22 Re: Climate Driver Discussion 2017 (Enso, IOD, PDO ,SAM etc) [Re: ColdFront]
GringosRain Offline
Weatherzone Addict

Registered: 19/06/2007
Posts: 1576
Loc: Quorrobolong NSW
I dont think anybody knows exactly how it works TS, so starting off your posts with, "no this is not right" and "doesnt work that way" seem to suggest you have total authority over weather dynamics. Its just another opinion bud, and its probably a good one, but doesnt mean mine isnt equally so. There are so many variables, if that HPS was 800ks further west, with the correct combos of SAM, LWT, PDO, ENSO, SSTs etc there could be a million outcomes, including heavy rain or drought over your region. No absolutes, so dont present that way.
Isnt it raining in SA right now? Isnt it coming from the NW?
Some nice storms events about in the east....but no real Nina payday yet whichever way its spun. The blocking high just pushes on for the forecast period with some evidence in the models that what I have described above will mean more rain for SA in the coming weeks....

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