Goni and Atsani

Original post

Final update: AP report on August 25, 2015.

Update, Friday, August 21, 2015, 1:05 p.m. Pacific: Goni has gotten close enough to the Philippines to kill at least four people and cause the evacuation of thousands, per news reports.

Per the Joint Typhoon Warning Center, Goni is practically stationary. This is not good news for the northern Philippines. There, PAGASA says, there is:

  • Heavy damage to high–risk structures
  • Moderate damage to medium- risk structures
  • Light damage to low-risk structures
  • Increasing damage (up to more than 50%) to old, dilapidated residential structures and houses of light materials. Majority of all nipa and cogon houses may be unroofed or destroyed
  • Houses of medium strength materials (old, timber or mixed timber-CHB structures, usually with G.I. roofing’s); some warehouses or bodega-type structures are unroofed
  • There may be widespread disruption of electrical power and communication services
  • Almost all banana plants are downed
  • Some big trees (acacia, mango, etc.) are broken or uprooted
  • Dwarf-type or hybrid coconut trees are tilted or downed
  • Rice and corn crops may suffer heavy losses
  • Damage to shrubbery and trees with foliage blown off; some large trees blown down

Storm surges up to 8 feet high are expected in that northernmost region, and these will be topped with powerful waves many tens of feet tall.

This typhoon is expected to track over Japan as the equivalent of a Category 2 Atlantic hurricane, the JTWC says, and may transition to an extratropical cyclone at the end of the period (still lots of rain and wind, but it’s not running on heat any more). However, they do point out that due to the complex steering environment, this forecast track is still low confidence.

In the meantime, Atsani, which has been so spectacular, is expected to remain out to sea.

Atsani, on the right, is still impressive.  Goni's structure has changed, but it is interacting with land and has begun its career of messing up human lives and property that will continue over the next several days.  (Image:  NOAA)

Atsani, on the right, is still impressive. Goni’s structure has changed, but it is interacting with land and has begun its career of messing up human lives and property that will continue over the next several days. (Image: NOAA)

Update, Thursday, August 20, 2015, 1:45 p.m. Pacific: Just a quick note: Goni now is expected to make landfall in southern Kyushu, Japan, Sunday evening, as the equivalent of a category 3 Atlantic hurricane. That’s “major” in the Atlantic basin though not “super” in the Pacific. The forecast track appears to go right up the middle of Japan, but the Joint Typhoon Warning Center notes it has low confidence in the track, and Goni might end up hitting the Korean peninsula instead.

Update, Wednesday, August 19, 2015, 9:20 a.m. Pacific: The Joint Typhoon Warning Center’s website appears to be offline just now. However, per the five-day forecast track posted by Dr. Jeff Masters it appears that Typhoon Goni may miss Taiwan and the northern Philippines and roll over Japan while weakened to a point much less than supertyphoon or even major-Atlantic-hurricane-equivalent intensity:


Hope that verifies, although it will be hard on Japan. The equivalent of Saffir-Simpson Atlantic category 3 and then 2 hurricanes are very damaging and pack a lot of rainfall. However, densely populated Eastern Asia has been hit by recent flooding too, and it would be good if this typhoon doesn’t add to the problem there. However, I’d like to read the JTWC discussion to see what confidence they have in this long-term track.

Amazingly, Supertyphoon Atsani is also forecast to stay out to sea during this period. Yay!


Here are links to Taiwan’s Central Weather Bureau and the Japan Meteorological Agency (both in English) so you can follow any updates on the scene. The online Japan Times, also in English, doesn’t appear to have anything on Goni just yet, but that may be a useful news source over the next week, too.

Meanwhile, the current IR image at NOAA’s Tropical West Pacific satellite page shows these two powerful cyclones still close to peak strength (Atsani, on the right, is peaking), and now they’re starting to pull away from each other and moving toward their separate fates (with Goni being watched very closely by the Philippines, of course):



(Note: The front page image is the current NOAA satellite IR imagery of Supertyphoon Atsani’s incredible eye. Wow!)

Update, Tuesday, August 18, 2015: OK, first of all, Atsani is now forecast to reach supertyphoon status on the 20th, when it’s expected to peak at 150 knots (160 mph/260 kph)! The Joint Typhoon Warning Center’s current discussion states high confidence in the long-term track, which for the next five days anyway should be over the ocean:

Joint Typhoon Warning Center

Joint Typhoon Warning Center


As for Goni, the JTWC now expects it to peak at 115 knots (which would still be a major hurricane in the Atlantic basin, with winds of 132 mph/213 kph). The good news (for Taiwan) is that the current forecast track shows Goni moving off Taiwan’s northeastern coast.

Joint Typhoon Warning Center

Joint Typhoon Warning Center


The bad news (for Taiwan) is that the JTWC has low confidence in this track and it only shows the storm’s center and there probably will still be interactions with Taiwan even if the track verifies totally. It’s still a wait-and-see game for them. Also, I wonder if the northwest quadrant of a Southern Hemisphere typhoon is as bad as the northeast quadrant of a Northern Hemisphere hurricane? If so, and if the track jigs a little to the left, that would be very bad news indeed.

Goni’s current forecast track is also bad news for Japan’s Yaeyama Islands at the tip of the Ryukyu Arc, some of which are right in its path. These beautiful little tourism gems were also affected by Soudelor’s recent passage.

With due concern for the human impact of these storms in the near and distant future, it’s still undeniably awesome to have not one, but two of the greatest natural shows on Earth playing out in the West Pacific at this moment. It’s dark there now, so here’s an IR satellite view of Goni (left) and Atsani (right), both near peak strength and still close enough to fit on a single image. Check out this NOAA Satellite Services link for visible views once daylight returns to the area!




Update, Monday, August 17, 2015: From space, both Goni and Atsani have rapidly intensified and have that unsettling “buzz-saw” appearance now:


The animated front-page image of Goni today is morphed microwave imagery at CIMSS.

Typhoon Atsani is still many days from any landfall, but media headlines are now starting to put the words “Goni,” “supertyphoon” and “Taiwan” together. However, Goni’s future and the fate (or escape) of Taiwan are by no means clear yet. The current JTWC discussion notes:


Their current graphical forecast for Goni shows it making the northern turn while still over water…


…but it’s just too early to tell for sure what’s going to happen this week. Read the whole discussion (linked above). One thing’s for sure. The words “weak steering currents” are never good when associated with any tropical cyclone, especially one that’s expected to have two peaks, at 125 and 130 knots (both wind speeds are in the strong Category 4 range on the Saffir-Simpson scale, which isn’t used in the Western Pacific, as far as I know).

As a matter of fact, Goni’s current 115-knot wind speed puts it just above the Category 4 threshold now.

Of note – and I didn’t know this – 130 knots (150 mph/241 kph) is the minimum cut-off for a supertyphoon. So despite what I said below and what you are hearing and seeing in the news right now, Goni may not actually become a supertyphoon. We’ll see. I’m more worried about the rain right now, especially if this cyclone stalls near or over land.

Update, Sunday, August 16, 2015: Both Goni and Atsani are in “cyclone heaven” now in terms of meteorological conditions and they’re at typhoon strength and still intensifying. Here’s an animated GIF of their development over the last day or so from the NOAA Satellite Services West Pacific Tropical home page (which loads very slowly at the moment – a lot of people are probably using it!):




Per the following graphic, which is from Taiwan’s Central Weather Bureau, Goni very well could hit the island later in the coming week.

That's Goni on the left. Atsani, on the right, seems to be far enough away, on this graphic anyway, for the Fujiwara effect not to be an issue. (Central Weather Bureau)

That’s Goni on the left. Atsani, on the right, seems to be far enough away, on this graphic anyway, for the Fujiwara effect not to be an issue. (Image: Central Weather Bureau)


However, in the current discussion posted on their website, the Joint Typhoon Warning Center is less confident on Goni’s forecast track that far down the road that it was yesterday. They presently expect Goni to peak at around 130 knots (150 mph/240 kph) on Thursday and then weaken considerably after that. However, as veteran stormchaser James Reynolds says, wind speed is less important than rainfall amount when typhoons hit Taiwan.

I’m only an amateur, but I find it concerning that the JTWC mentions that Goni might become almost stationary near Taiwan. If that does verify, let’s hope that it happens while Goni is over water!

As for Typhoon Atsani, although JTWC has only moderate confidence in the long-term track, it should stay out to sea during the next five days but head in the general direction of Japan. The Japan Meteorological Agency is also keeping a close watch on it.


Original post, August 15, 2015:
Taiwan doesn’t need any more rain right now but another supertyphoon may be visiting in the next week or so. Meet tropical storms Goni (left) and Atsani (right):


Goni, which currently shows up on Guam weather radar, is the one that will probably reach Taiwan’s neighborhood, though it looks like Goni might only affect the southern tip of the island, since the the US Navy’s Joint Typhoon Warning Center says that they are pretty confident in their forecast track:

Joint Typhoon Warning Center's graphic forecast for Goni at the time of writing this post.

Joint Typhoon Warning Center’s graphic forecast for Goni at the time of writing this post.


The JTWC says it isn’t yet sure about Atsani’s future course because it is moving very slowly right now.

I’m curious about Fujiwara interactions. Between them, Goni and Atsani occupy a whole latitude/longitude block. They appear about equal in strength, and I wonder if they are orbiting each other or likely to in the near future. I haven’t seen any mention of it in the JTWC discussions. Time will tell, I guess!

Categories: Weather

Tags: , , , ,

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

%d bloggers like this: