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Hong Kong Braces for Category 3 Typhoon Usagi

By: Dr. Jeff Masters , 4:25 PM GMT on September 21, 2013

Dangerous Category 3 Typhoon Usagi is charging through the Luzon Strait between Taiwan and the Philippines on its way towards China, where landfall is expected early Monday morning local time (near 2 pm EDT on Sunday) near Hong Hong. The typhoon battered the northern Philippine Batanes Islands overnight with wind gusts of up to 155 mph (250 kph), ripping down power lines and damaging crops, according to the South China Morning Post. Torrential rains of over a foot (305 mm) have fallen in 24 hours over eastern Taiwan, where Usagi's counterclockwise flow of moist air rode up over the high mountains of the island. Usagi reached its peak strength on Thursday, taking advantage of low wind shear and very warm waters 30°C with high heat content, to intensify to a Category 5 super typhoon with 160 mph winds. On Friday, Usagi began an eyewall replacement cycle that the typhoon is still attempting to complete. This process, where the inner eyewall collapses and a new, larger-diameter eyewall forms from an outer spiral band, typically causes a reduction in intensity by one Saffir-Simpson category, but spreads out the storm's hurricane-force winds over a larger area. Satellite images show that Usagi has lost its symmetry and the cloudtops have warmed, indicating weakening; this weakening is likely due to disruption of the low-level inflow by the high mountains of Taiwan. Wind shear is low, near 10 knots, but ocean temperatures have cooled to about 29°C, and the heat content of the waters is much lower than on Friday.


Figure 1. MODIS satellite image of Typhoon Usagi, taken at approximately 04:30 UTC on September 21, 2013. At the time, Usagi was a Category 4 typhoon with 140 mph winds. Image credit: NASA.


Figure 2. Rainfall in Taiwan for the 24-hour period ending at 12 pm EDT (midnight in Taiwan) on Saturday, September 21, 2013. Rainfall amounts in excess of 300 mm (11.81", yellow colors) fell in less than 24 hours in several regions. Image credit: Central Weather Bureau.

Forecast for Usagi
Continued slow weakening of Usagi is likely as the storm tries to complete its eyewall replacement cycle as ocean temperatures cool to 28°C and the heat content of the water diminishes. By the time Usagi reaches the coast near Hong Hong in the early morning hours on Monday (local time), the storm should be at Category 2 strength. This is still strong enough to pose a formidable storm surge, wind, and heavy rain threat to China, and Usagi is likely to be one of the five strongest typhoons to affect Hong Hong in the past 50 years. If the eye of the storm hits just west of Hong Kong, a large storm surge capable of causing over a billion dollars in damage will inundate portions of the coast along the bay that Hong Kong, Macau, and Shenzhen share. Wunderground's weather historian, Christopher C. Burt, has a new post, Hong Kong's typhoon history, detailing the most notable storm's in Hong Hong's history. The most notable typhoon to hit Hong Kong in the past 50 years was Typhoon Rose of 1971, which sank over 300 boats and killed 110 people.


Figure 3. Super Typhoon Usagi, as seen by the VIIRS instrument on the Suomi satellite on Thursday, September 19, at 1635 UTC (375-m I-band 5). At the time, Usagi was a Category 5 super typhoon with 160 mph winds. The eye is at its narrowest at the surface, and slopes outward with altitude (like being inside a stadium), so that the cloud temperatures measured in infrared light in this image change dramatically surrounding the eye. The warmest brightness temperature inside the eye in this image is -11°C, which suggests that we are seeing a mid-level cloud deck in the center of the eye. Image credit: Dan Lindsey, NOAA/RAMMB/CIRA.


Figure 4. Visible light image from VIIRS taken under the full moon at the same time as the above infrared-light image. Image credit: Dan Lindsey, NOAA/RAMMB/CIRA.

Usagi Links
Southeast China radar

The University of Wisconsin CIMSS Satellite Blog has a nice animation showing the trochoidal (wobbling) forward motion characteristic of intense tropical cyclones.


Video 1. Typhoon chaser James Reynolds caught video of some impressive surf from Typhoon Usagi impacting Taiwan on September 21, 2013. His Twitter feed is here. He is now in Hong Hong to document the storm's arrival there.

Vulnerability assessment of storm surges in the coastal area of Guangdong Province, a 2011 journal article by Li and Li.

Quiet in the Atlantic
There are no tropical cyclone threat areas in the Atlantic to discuss today, and none of the reliable models for tropical cyclone formation is predicting development during the coming five days.

Jeff Masters


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

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624. indianrivguy
6:00 PM GMT on September 22, 2013
Quoting 516. PalmBeachWeather:
I heard that IRG... Is this a catch-22 IRG?


well, the futility is nearly the same...
Member Since: December 31, 1969 Posts: Comments:
623. whitewabit
5:38 PM GMT on September 22, 2013
new blog up Skye !!
Member Since: December 31, 1969 Posts: Comments:
622. Skyepony (Mod)
5:36 PM GMT on September 22, 2013
~
Member Since: December 31, 1969 Posts: Comments:
621. BahaHurican
5:13 PM GMT on September 22, 2013
Uh... New blog?
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620. Jedkins01
5:05 PM GMT on September 22, 2013
Who said sea serpents are myth? This is probably what ancient people have seen when describing a sea serpent :)


Member Since: December 31, 1969 Posts: Comments:
619. vis0
5:03 PM GMT on September 22, 2013
Quoting 451. mikatnight:
Good Morning!
6:58 am (10:58 GMT)

........
I hope everyone has been doing well in my absence. I must confess I haven't even had a chance to check in at all aside from reading Jeff's posts ...

Dexter is doing just fine (in case you were wondering), however his best friend Marley got attacked ... Marley is doing much, much better now, and even got to pal around with Dex for a bit yesterday. Meanwhile, this morning, I asked Dex what he thought of this year's hurricane season......

We got a couple of good rain days last week. If this next forecasted batch dumps on us, September might end up being the wettest of the year. It's gonna take over 4" to beat May's 14" though.

Have a great Sunday everyone! Go Fish!








1) Relieved to read Marley is better.
2) If a tree falls in the forest and no one is around we still don't know if it makes a noise but darn sure Dexter will be in the picture before the tree hits the ground.
3) And why is Dexter looking Northward? for hurricanes...just kidding i can't tell in which direction Dexter's looking.
Member Since: December 31, 1969 Posts: Comments:
618. LoneStarWeather
5:03 PM GMT on September 22, 2013
Quoting 602. Abacosurf:

Definitely some rotation.



Some wind too.

You could see it spinning just off-shore on the Brownsville radar yesterday. No doubt the rotation is intact.
Member Since: December 31, 1969 Posts: Comments:
617. BahaHurican
4:58 PM GMT on September 22, 2013
Quoting 499. LAbonbon:


Mmmm, Mmmm! The apple slice pancakes were really really good. Thanks for the idea.

Maybe next weekend it'll be the banana fritters :)

Plaintain is better... don't even need the batter... lol

Quoting 501. SLU:


A drought advisory may need to issued for the islands soon because we're looking at the prospect of about 8 - 9 months of bone dry weather on the heals of this bust season with well below normal rainfall.
The way things have been going, u guys could end up with an excessively wet "dry" season. Not saying it will happen, but things have been so contrary to expectation this season that just about anything seems possible.....

Quoting 526. Tazmanian:
i really think hurricane season is done for this year has we are starting too get more and more fall like winter storms in fac Montana could be looking at the 1st winter storm watch of the season

They had frost warnings up that way much of last week. And not just in the mountains.

Quoting 557. FunnelVortex:


What part of "upper Midwest" don't you understand?
Obviously, the MID part. You didn't even need to ask...

Quoting 584. flsky:


Posting a link takes up less blog space than loooooong articles.
Wonder which is easier for pple on phones and tablets? the article in the blog or the link, necessitating a new window?
Quoting 591. GTstormChaserCaleb:
9/2/0 to this point. We still have October and November to fill in. My prediction of 15/8/5 still stands, but I am least confident that all of my numbers will verify. I'll go with the named storms verifying.

I agree. I think the NS will verify. The 8 hurricanes? hmmm... we have had only 2 so far, so that means we'd have to get 6 more in the CAR and NW ATL for that to verify. I had 4 majors, and I doubt that we'll see that verify.

There's got to be something we can use to predict this sinking air in order to improve seasonal forecasts... what are we missing?
Member Since: December 31, 1969 Posts: Comments:
616. redwagon
4:56 PM GMT on September 22, 2013
Quoting 603. wxgeek723:
Like I said, people will not give up on this season until Christmas music starts playing on the radio.


Is it OK to wait til Dec 1 (end of season) before we give up on it? We're supposed to just walk out at half-time?
Member Since: December 31, 1969 Posts: Comments:
615. beell
4:56 PM GMT on September 22, 2013
The Cyclone Model-Part 1

The temperature gradients are not as extreme as in the examples. Consequently, neither is the strength of the system.
Member Since: December 31, 1969 Posts: Comments:
614. washingtonian115
4:54 PM GMT on September 22, 2013
Quoting 603. wxgeek723:
Like I said, people will not give up on this season until Christmas music starts playing on the radio.
I don't care who you are.Now that's funny.It'll be January and people will be saying don't give up.Meanwhile we're tracking winter storms.
Member Since: December 31, 1969 Posts: Comments:
613. muddertracker
4:54 PM GMT on September 22, 2013
Good grief. There's NOTHING to talk about in the Atlantic. A few people may need to seriously reconsider their fiber intake. Lighten up!

Member Since: December 31, 1969 Posts: Comments:
612. wxchaser97
4:52 PM GMT on September 22, 2013
Quoting 603. wxgeek723:
Like I said, people will not give up on this season until Christmas music starts playing on the radio.

Lol, it starts in just over a month for me.
Member Since: December 31, 1969 Posts: Comments:
611. 7544
4:52 PM GMT on September 22, 2013
Quoting 602. Abacosurf:

Definitely some rotation.



Some wind too.


agree looks like a little se drift there too if it could get further south today and avoid all that dry air to the north it could pop keeeps one eye on it .
Member Since: December 31, 1969 Posts: Comments:
610. Abacosurf
4:52 PM GMT on September 22, 2013
Quoting 606. TropicalAnalystwx13:
Has nobody ever seen a frontal low before? Everybody is going crazy on Facebook and Twitter about the NHC completely ignoring a tropical cyclone in the northwestern Gulf. The low does not meet the qualifications to be considered a subtropical or tropical cyclone because it's connected to a cold front.
Now that we name all storms all year people think everything needs a designation or people will not know what to do. It's called dumbing down.
Member Since: December 31, 1969 Posts: Comments:
609. MahFL
4:51 PM GMT on September 22, 2013
Quoting 606. TropicalAnalystwx13:
Has nobody ever seen a frontal low before? Everybody is going crazy on Facebook and Twitter about the NHC completely ignoring a tropical cyclone in the northwestern Gulf. The low does not meet the qualifications to be considered a subtropical or tropical cyclone because it's connected to a cold front.


You can see the feeder bands coming in from the south.
Member Since: December 31, 1969 Posts: Comments:
608. GTstormChaserCaleb
4:51 PM GMT on September 22, 2013
Interesting I saw this on this mornings GFS run.

Member Since: December 31, 1969 Posts: Comments:
607. WunderAlertBot (Admin)
4:50 PM GMT on September 22, 2013
JeffMasters has created a new entry.
606. TropicalAnalystwx13
4:45 PM GMT on September 22, 2013
Has nobody ever seen a frontal low before? Everybody is going crazy on Facebook and Twitter about the NHC completely ignoring a tropical cyclone in the northwestern Gulf. The low does not meet the qualifications to be considered a subtropical or tropical cyclone because it's connected to a cold front.
Member Since: December 31, 1969 Posts: Comments:
605. PalmBeachWeather
4:42 PM GMT on September 22, 2013
Quoting 603. wxgeek723:
Like I said, people will not give up on this season until Christmas music starts playing on the radio.
"Chestnuts roasting on an open fire"
Member Since: December 31, 1969 Posts: Comments:
604. PalmBeachWeather
4:39 PM GMT on September 22, 2013
Quoting 603. wxgeek723:
Like I said, people will not give up on this season until Christmas music starts playing on the radio.
Heck.... They had Halloween costumes for sale at Walmart a month ago
Member Since: December 31, 1969 Posts: Comments:
603. wxgeek723
4:38 PM GMT on September 22, 2013
Like I said, people will not give up on this season until Christmas music starts playing on the radio.
Member Since: December 31, 1969 Posts: Comments:
602. Abacosurf
4:35 PM GMT on September 22, 2013
Quoting 598. MahFL:
I my opinion a low is definitely forming in the NW Gulf, you can see the banding curving.

Definitely some rotation.



Some wind too.
Member Since: December 31, 1969 Posts: Comments:
601. redwagon
4:33 PM GMT on September 22, 2013
Quoting 583. KEEPEROFTHEGATE:



stop it now yous


lol




Lookit these twins in the monsoon trof.
Member Since: December 31, 1969 Posts: Comments:
600. bappit
4:33 PM GMT on September 22, 2013
Quoting 533. congaline:
I always ck out NHC before coming here to see Sat images and get a feel for what's moving out there. Surprised to see the low in the gulf blowing up again at tail of cold front. Showing improvement in circ and convection firing, I think they need to put a circle around it again. Might even be a TS before it reaches Eastern gulf. At least some fun inclement weather headed this way. Usagi sure is pretty to look at.

It is strictly extra tropical. Beautiful day in Houston. Low was in the mid-60's last night. Dry air. Beautiful blue skies. Dew points running a little high because of all the rain we had. Woot!
Member Since: December 31, 1969 Posts: Comments:
599. BahaHurican
4:31 PM GMT on September 22, 2013
Quoting 451. mikatnight:
Good Morning!
6:58 am (10:58 GMT)

7:14

7:25

Sunrise in Lantana Florida overlooking the Intracoastal Waterway.

I hope everyone has been doing well in my absence. I must confess I haven't even had a chance to check in at all aside from reading Jeff's posts - I've been busier than a one-legged dude in a butt-kicking contest...

Dexter is doing just fine (in case you were wondering), however his best friend Marley got attacked by a much larger dog last week and had to be rushed to the hospital. We are very relieved and pleased to report that Marley is doing much, much better now, and even got to pal around with Dex for a bit yesterday. Meanwhile, this morning, I asked Dex what he thought of this year's hurricane season...

Oh well, everybody has an opinion.


I am way too fast for you! Hahahahahahaha

On the way home we stopped by the tennis courts to play a little ball. I couldn't get a decent picture, but here's one from last year, playing tug-of-war with Mom...
6:33 pm (sunset), October 15, 2012


So Dex, is this the end of hurricane season?

Hmmmmm. Still a long way to the end of November. Wishful thinking, or perhaps...prescient?

We got a couple of good rain days last week. If this next forecasted batch dumps on us, September might end up being the wettest of the year. It's gonna take over 4" to beat May's 14" though.

Have a great Sunday everyone! Go Fish!
Great series, Mik! I'm glad to here my fave canine pal is doing well and as opinionated as ever... lol
Member Since: December 31, 1969 Posts: Comments:
598. MahFL
4:30 PM GMT on September 22, 2013
I my opinion a low is definitely forming in the NW Gulf, you can see the banding curving.
Member Since: December 31, 1969 Posts: Comments:
597. PalmBeachWeather
4:21 PM GMT on September 22, 2013
Quoting 595. GTstormChaserCaleb:
By the way where are my manners...Good Sunday morning everyone.
Good afternoon GT
Member Since: December 31, 1969 Posts: Comments:
596. PalmBeachWeather
4:18 PM GMT on September 22, 2013
Quoting 583. KEEPEROFTHEGATE:



stop it now yous


lol
Ok... Sorry.
Member Since: December 31, 1969 Posts: Comments:
595. GTstormChaserCaleb
4:18 PM GMT on September 22, 2013
By the way where are my manners...Good Sunday morning everyone.
Member Since: December 31, 1969 Posts: Comments:
594. ncstorm
4:17 PM GMT on September 22, 2013
Quoting 584. flsky:


Posting a link takes up less blog space than loooooong articles.


and your comment is blog worthy?..LOL..

You guys have fun bickering and complaining..I'm off to watch some sunday football..
Member Since: December 31, 1969 Posts: Comments:
593. weatherxtreme
4:16 PM GMT on September 22, 2013
I have to admit this has been a slow and almost uneventful season. I like to track these storms just like everyone else but am thankful we haven't had any large damaging storms this year. I know I am really tiring of all the rain we keep getting in Florida as there really isn't anywhere else for it to go.
Member Since: December 31, 1969 Posts: Comments:
592. TropicalAnalystwx13
4:16 PM GMT on September 22, 2013
Quoting 578. Tazmanian:





ok then if we can get from now tell NOV 30th with out a name storm then i come back on NOV 30th and say i was right the hole time

oh dont worry i still be here posting two lol

Okay.
Member Since: December 31, 1969 Posts: Comments:
591. GTstormChaserCaleb
4:15 PM GMT on September 22, 2013
9/2/0 to this point. We still have October and November to fill in. My prediction of 15/8/5 still stands, but I am least confident that all of my numbers will verify. I'll go with the named storms verifying.

Member Since: December 31, 1969 Posts: Comments:
590. Orcasystems
4:15 PM GMT on September 22, 2013
Quoting 588. KEEPEROFTHEGATE:
hello big fish good sunday too ya


That it is.. but I do miss the sunny weather... its been gone for a few days now :(
Member Since: December 31, 1969 Posts: Comments:
589. hurricanes2018
4:15 PM GMT on September 22, 2013
good news here
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588. KEEPEROFTHEGATE (Mod)
4:14 PM GMT on September 22, 2013
Quoting 587. Orcasystems:


:)
hello big fish good sunday too ya
Member Since: December 31, 1969 Posts: Comments:
587. Orcasystems
4:13 PM GMT on September 22, 2013
Quoting 583. KEEPEROFTHEGATE:



stop it now yous


lol


mod = Duty Babysitter :)
Member Since: December 31, 1969 Posts: Comments:
586. GTstormChaserCaleb
4:12 PM GMT on September 22, 2013
In the world of sports it is the 2nd half of where games are won. If you want to tie that in to the hurricane season think of it as getting off to a bad start and coming from behind to win the game. October is just around the corner and will see more activity than September.
Member Since: December 31, 1969 Posts: Comments:
585. LargoFl
4:12 PM GMT on September 22, 2013
Member Since: December 31, 1969 Posts: Comments:
584. flsky
4:11 PM GMT on September 22, 2013
Quoting 564. ncstorm:


Posting a link takes up less blog space than loooooong articles.
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583. KEEPEROFTHEGATE (Mod)
4:11 PM GMT on September 22, 2013
Quoting 581. PalmBeachWeather:



stop it now yous


lol
Member Since: December 31, 1969 Posts: Comments:
582. Hurricanes101
4:10 PM GMT on September 22, 2013
Quoting 577. KEEPEROFTHEGATE:
true taz is not a mod but your use of shutup was just as uncalled for but I understand and say that's once


Thank you, I did not use the word to directly tell someone to do that. It was more of a general comment
Member Since: December 31, 1969 Posts: Comments:
581. PalmBeachWeather
4:08 PM GMT on September 22, 2013
Quoting 552. Hurricanes101:
wow seems the whiners are on here in full force today

Oh no, the season is not what we thought, big deal. There are other things more important. Also the activity so far this year has no bearing on what will happen for the rest of it. We very easily could end up with a high impact system next month as the main development areas in October have been largely untouched and those waters are still very warm

If we get a late season storm with high impact, that should shut some people up
My goodness 101... You seem to have gotten up on the wrong side of the bed.... Speaking of whining,you seem to be in the lead. You can only whine for so long, then you need to get your life back 101
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580. washingtonian115
4:08 PM GMT on September 22, 2013
Quoting 574. Hurricanes101:


well its implied when we have a strengthening hurricane in the BOC with the potential to cause massive flooding in Mexico and you come on complaining about the storm because it developed in the BOC

You hate that all the storms developed on there and you would come on here and make your frustrations known, while some of us were looking at the storm.

Sorry just my opinion. I will leave it alone now
Maybe if it was two storms that developed in the BOC there wouldn't be a problem.But more than half of the storms formed there this season.Making it very predictable.I want a long track beautiful hurricane like Danielle in 2010 and 2004.
Member Since: December 31, 1969 Posts: Comments:
579. LargoFl
4:08 PM GMT on September 22, 2013
Member Since: December 31, 1969 Posts: Comments:
578. Tazmanian
4:07 PM GMT on September 22, 2013
Quoting 573. TropicalAnalystwx13:

It may end early, it may not. We have no way of knowing for sure. Declaring it completely over on September 22 is completely foolish.





ok then if we can get from now tell NOV 30th with out a name storm then i come back on NOV 30th and say i was right the hole time

oh dont worry i still be here posting two lol
Member Since: December 31, 1969 Posts: Comments:
577. KEEPEROFTHEGATE (Mod)
4:07 PM GMT on September 22, 2013
Quoting 572. Hurricanes101:


you are not a mod Taz, quit acting like one
true taz is not a mod but your use of shutup was just as uncalled for but I understand and say that's once
Member Since: December 31, 1969 Posts: Comments:
576. LargoFl
4:06 PM GMT on September 22, 2013
Quoting 561. FunnelVortex:


There we see our nor'easter developing from former 95L
yes something to watch next week.
Member Since: December 31, 1969 Posts: Comments:
575. washingtonian115
4:05 PM GMT on September 22, 2013
Quoting 563. KEEPEROFTHEGATE:
there is another strong front for next weekend as well early week


06z gfs

12z is currently running awaiting results

I'm not complaining.We need the rain.We've been running a 3 inch deficit.
Member Since: December 31, 1969 Posts: Comments:
574. Hurricanes101
4:05 PM GMT on September 22, 2013
Quoting 571. washingtonian115:
Lol.can you point that out?.And I've barely been blogging.When did I say I wanted a storm to impact the U.S?.I said I wouldn't mind a 2010 season where all the majors stayed out to sea.There you go putting words into peoples mouth.


well its implied when we have a strengthening hurricane in the BOC with the potential to cause massive flooding in Mexico and you come on complaining about the storm because it developed in the BOC

You hate that all the storms developed on there and you would come on here and make your frustrations known, while some of us were looking at the storm.

Sorry just my opinion. I will leave it alone now
Member Since: December 31, 1969 Posts: Comments:

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Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather

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