Tulamben, Mount Agung, Current Situation...

[Dan]

No one at this stage what type of eruption may (or may not) occur. Pyroclastic flows, ash, lava?
Evidently the 1963 eruption lasted for a year, but as we in New Zealand know, just because a volcano is in a state of eruption does not mean that it is hazardous to a wide area. It is an ash cloud that is hazardous to air traffic, but often air traffic can be safely routed around the cloud - just has occurred here in New Zealand with Ruapehu and Tongariro. Pyroclastic flows are very hazardous, but the distance they can travel isn’t so great - this will be one of the deciding factors in the current evacuation zones.
Until Agung's eruption really gets underway I don’t think anyone knows what will happen and even then trying to predict how long it will last? Again it’s a case of wait and see.
I just hope that it doesn’t go on for too long and that people stay safe and a minimum of damage is done to the diving areas close to Gunung Agung - afterall the 1963 eruption put the Liberty in the water where she is now

Agreed.

Here is more info about the type of eruption it may create, based on the previous data collected from 1808, 1821, 1843 & 1963 eruptions, the patterns were about the same, that is explosive, shooting up firing rocks, molten lava, raining of pyroplastic lava & ash. Unlike the Eyjafjallajokull eruption in Iceland in 2010 that was emitting a lot of ashes and creating commercial jet traffic problem to about 20 countries, the past Agung eruptions did not produce such thick & wide spread ashes, according to the News Conference for Anticipation of Mount Agung Eruption taken place on Monday, Sep 25, 2017 (2 days ago) in Jakarta that I posted earlier the first couple pages of the presentation. I uploaded the full PDF of the presentation in my Dropbox, below. Unfortunately it is in Bahasa Indonesia. You can use Google Translate to decipher the content:
Dropbox - 45787_Konferensi pers antispasi erupsi Gunung Agung_25 Sep 2017.pdf

The plume of ash may hover within the island and head in northwest direction, according to this model:

 

[billt4sf]

As I mentioned in an earlier post, I am firmly double parked in the “wait and see” camp. As Nettie posted, at this point we really can not accurately forecast to eruptive frequency, magnitude, or duration.

Me, too, but I am glad I am not waiting in Amed or Tulamben. Here in Ubud, we are about 20 miles away as the crow flies.

- Bill

 

[billt4sf]

Does anyone know what direction the prevailing winds at altitude are?

From my point of view it would be great if the ash is blown as Dan's map has it.

- Bill

 

[Centrals]

Does anyone know what direction the prevailing winds at altitude are?

From my point of view it would be great if the ash is blown as Dan's map has it.

- Bill

I assumed you have stocked up some dust masks just in case.

 

[Scubamat]

My trip is a month away so I should know by then. I only have flights booked with tentative diving plans that did include liberty. Not going to outright cancel my trip maybe just adjust the dive locations slightly spending more time on Gili.

The best thing a tourist can do post event in a tourist area like Bali is the come back once things start to settle down and help get the dollars flowing again.

 

[Dan]

Does anyone know what direction the prevailing winds at altitude are?

From my point of view it would be great if the ash is blown as Dan's map has it.

- Bill

Ya, I surely like to know too.

Here is my guess, being in the equatorial zone and due to the earth rotation (moving from west to east), assuming there is no localized high pressure zone that would counter the wind direction due to the natural Earth rotation drag, I would think westerly direction make sense. That's why hurricane, being in the northern hemisphere, naturally would rotate in counter clockwise direction and moving in westerly direction from west Africa to US east coast and it gets stronger as it moves over the Atlantic Ocean. The warm sea temperature fuels the storm into a hurricane by the time it arrives in Bahama & Caribbean.

Now, why would it go to the northwest direction?My guess is the temperature change would also help the wind direction. Warmer air would expand and cooler air would contract. So wind would go from warmer to cooler atmosphere. In the morning, as the sun is shining the earth surface, the land, being a better heat conductor than water, would get warm sooner than the sea, so the morning wind would be going from land to sea to fish in the morning. In the old days, fishermen take advantage of this seaward wind and use sailboat to go out to the sea to go fishing. The sea next to Mount Agung is in the north. In the evening the reverse is true around coastal region, However, the southern larger land mass from Ubud down to Kuta will always be warner than the Mount Agung summit and creating high pressure zone wall that keep the coastal wind from going further south than Tulamben. Therefore, the northwest direction seems to make sense to me. And Ubud would be a safe place for you to hangout.

 

[Nettie-NZ]

Dan - nice logic, but there are also seasonal issues as well. Below is some more info. I’ve seen this in more detail somewhere else, but I couldn’t find it again in a hurry. But the prevalent wind direction does change with season, so the answer after November is different....


Bali News: The Answer is Blowing in the Wind
Experts Predict that if Mount Agung Erupts Before November, Volcanic Ash will Drift to the Skies to Bali’s North

‘Taufik Gunawan, the head of the Meteorology, Climate and Geophysics Agency (BBMKG) for Denpasar shared this projection. Continuing, he said: “Based on the current prevailing winds blowing from the east-southeast, the pattern of any clouds of volcanic ash will be to the west and north of Mount Agung. The tendency will be for any cloud will spread to the north with winds blowing from the southeast.”’

 

[Nettie-NZ]

You can also find a good summary of information from official sources compiled and in English here:
In the Company of Volcanoes: Agung Volcano Unrest Information

 

[gekodivebali]

Agreed.

Here is more info about the type of eruption it may create, based on the previous data collected from 1808, 1821, 1843 & 1963 eruptions, the patterns were about the same, that is explosive, shooting up firing rocks, molten lava, raining of pyroplastic lava & ash. Unlike the Eyjafjallajokull eruption in Iceland in 2010 that was emitting a lot of ashes and creating commercial jet traffic problem to about 20 countries, the past Agung eruptions did not produce such thick & wide spread ashes, according to the News Conference for Anticipation of Mount Agung Eruption taken place on Monday, Sep 25, 2017 (2 days ago) in Jakarta that I posted earlier the first couple pages of the presentation. I uploaded the full PDF of the presentation in my Dropbox, below. Unfortunately it is in Bahasa Indonesia. You can use Google Translate to decipher the content:
Dropbox - 45787_Konferensi pers antispasi erupsi Gunung Agung_25 Sep 2017.pdf

The plume of ash may hover within the island and head in northwest direction, according to this model:
View attachment 428149

That's great stuff Dan. Thanks for this!

 

[Dan]

Dan - nice logic, but there are also seasonal issues as well. Below is some more info. I’ve seen this in more detail somewhere else, but I couldn’t find it again in a hurry. But the prevalent wind direction does change with season, so the answer after November is different....


Bali News: The Answer is Blowing in the Wind
Experts Predict that if Mount Agung Erupts Before November, Volcanic Ash will Drift to the Skies to Bali’s North

‘Taufik Gunawan, the head of the Meteorology, Climate and Geophysics Agency (BBMKG) for Denpasar shared this projection. Continuing, he said: “Based on the current prevailing winds blowing from the east-southeast, the pattern of any clouds of volcanic ash will be to the west and north of Mount Agung. The tendency will be for any cloud will spread to the north with winds blowing from the southeast.”’

Thanks for the link. I forgot about the seasonal winds that the old merchant sailor used to sail east to west or vice versa for trading.

After November, the wind will go to the east. That means people living in the south, like Ubud (Bill), Sanur & Denpasar (airport) will still be fine, Good to know.

I wish it to not ever erupt for another 50 years.