The Australian Weather Forum

Agreed, a negative IOD is what we need and is the most reliable producer of rain in SE Australia. If the SAM plays ball we could get one of those wet winters that fills up all the storages. Here is hoping after this horrid flash drought.

Now this has got me interested. It wouldn't be the first time we had a dry start to a year that had a wet winter. Combined with Neutral SOI, it could mean a ripper of a snow season.

I have a question that may not necessarily be on topic. Why do coastal rain events dump their highest rain right on the coast and not on top of the Dividing range? You see this in NSW coast and Gippsland. In fact look at today's 24 hour totals to see this effect in the Hunter Valley.

However, when we get rain from the NW from the inland, the top of the ranges gets the highest falls.

Kind of depressing these coastal events don't put more rain into the inland areas.

Good question flyfisher....

Fairly complex subject with topography, atmosphere and sea temps etc....but my 2 cents worth on your examples would come down to a couple of important factors. If sea temps are warmer than the land temps, significant moisture advection can come into play, especially with surface lows. Coastal areas and mountains near the coast can get some incredible streaming. The classic NW cloud band during winter months which hit the range is more an upper level beast along with the range rain shadowing areas like Melbourne. So many other considerations as well....needs a whole thread

Another surge in Indian Ocean SST around indo in the last 7 days. Winter is becoming interesting

Interesting to see BOM's latest 3 month outlook sticking with average to above average rainfall for Vic: http://www.bom.gov.au/climate/outlooks/ ... seasonal/0

I had expected they might have bailed by now, but not so!

Gordon wrote: ↑Thu Apr 12, 2018 2:19 pm Interesting to see BOM's latest 3 month outlook sticking with average to above average rainfall for Vic: http://www.bom.gov.au/climate/outlooks/ ... seasonal/0

I had expected they might have bailed by now, but not so!

Yes Gordon and the latest BoM along with NASA modelling is still showing a solid negative IOD for winter. Water off Indonesia is still warming also.

This is getting very interesting now. UKMO model, arguable top 2 in the world is now showing a negative IOD in July EC not quite there but the UK update is significant.

Kind of hard to imagine right now as the water near WA keeps cooling. Obviously, something is going to kick in quickly to change that - perhaps once the Indian ocean reverse flows back towards India? That will cool water near Africa and our water will then be "relatively" warm?

The Indian ocean off WA continues to cool and right up to Indonesia. It's looking very much like a positive IOD right now which means less moisture for southern systems and possibly continued drought. It's really going to have to turn around to change things.

flyfisher wrote: ↑Tue May 01, 2018 9:08 am The Indian ocean off WA continues to cool and right up to Indonesia. It's looking very much like a positive IOD right now which means less moisture for southern systems and possibly continued drought. It's really going to have to turn around to change things.

Perhaps there's something lurking under the surface that the BOM know about and we don't?

That said, I'm sick and tired of March weather in May. AAO is heading the wrong direction too for decent cold fronts atm.

We can pretty much lock-in a -ve IOD over winter. Go you good thing.
http://www.bom.gov.au/climate/model-sum ... dian-Ocean

Something is definitely brewing....

BOM Seasonal outlook today is extremely pessimistic about the next 3 months - hot and dry due to a prediction of higher than average air pressure in Southern Australia.
http://www.bom.gov.au/climate/outlooks/ ... w/summary/

I think they'll be wrong, given the way the IOD is trending: http://www.bom.gov.au/climate/enso/indi ... okmark=iod

There is a massive upwelling in the Indian Ocean south of Sri Lanka. Take a look at nullschool and select currents and sea surface anomalies.

https://earth.nullschool.net/#current/o ... ,-8.00,825

This keeps up and our NW cloud bands (or the weather systems that form them) won't have a chance. I wonder what causes such a huge upwelling? Positive IOD on the cards with an El Nino in the Pacific forming.... sad..

Here I have tried to graphically represent what is happening with the ocean temps and why we are having drought like conditions - or at least lack of tropical moisture into southern systems.

3.4 nino - has dipped again. Now closer to La Nina than El Nino. Models got August wrong as well. I've been waiting for the worm to turn but it's turning the other way for 3.4 nino Atmosphere is currently not in sync with the ocean in the Pacific. Maybe this might change soon, maybe it wont....probably know in a month from now.

Nino 3.4 has bounced back well into the +ve's this week. Now at 0.3c.

Indonesia has been having a drought too:
http://www.abc.net.au/news/2018-09-20/d ... a/10249940

Trade winds are dropping around the equatorial Pacific..... SST's are spiking. El Nino well and truly back on the table