Typhoon Roke bears down on Japan; 98L continues to grow more organized

By: Dr. Jeff Masters , 6:48 PM GMT on September 20, 2011

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Powerful Category 3 Typhoon Roke is bearing down on Japan, and is expected to hit the main island of Honshu on Wednesday morning, local time. Roke is on a dangerous track for Japan, one that would take the storm over some of the most heavily populated areas of the country. Heavy rains from Roke have already reached the coast of Japan, as seen on Japanese radar. However, Roke is starting to weaken, as seen in latest satellite imagery. The eye is no longer apparent, the cloud tops have warmed, and a slot of dry air has gotten wrapped into the storm's northwest side. Wind shear should continue to weaken Roke as it approaches landfall; shear is currently a high 20 knots, and will increase to 30 knots by Wednesday morning. Given the current weakening trend, I expect Roke is most likely to be a Category 2 typhoon at landfall.

Typhoon's Roke's storm surge, winds, and heavy rains will all be a concern. A damaging storm surge is likely to the right of where the center makes landfall, since Roke is a large storm whose winds are spread out over a wide area. If Roke tracks farther to the east than expected, a large storm surge may affect Tokyo Bay. Perhaps the biggest concern from the storm is heavy rain. The soils over much of Japan are saturated from the passage of Tropical Storm Talas during the first week of September. Talas was a very slow moving storm, and brought extreme rainfall amounts of over six feet to some portions of Japan. Roke is expected to bring up to 20 more inches of rain along its path. Roke could bring winds of 30 - 40 mph and heavy rains of 3 - 5 inches to the damaged Fukishima-Dai-Iche nuclear plant northeast of Tokyo.


Figure 1. MODIS image of Typhoon Roke taken at 1:45 pm local time (4:45 UTC) on Tuesday, September 20, 2011. At the time, Roke was a Category 2 storm with 110 mph winds. Image credit: NASA Earth Observatory.

Invest 98L continues to grow more organized
A tropical wave midway between Africa and the Lesser Antilles (Invest 98L) has increased in organization this afternoon, but still lacks a well-defined surface circulation. Satellite imagery shows a number of curved spiral bands have formed this afternoon, and the area covered by heavy thunderstorms has steadily increased. An ASCAT pass from 8:21 am EDT this morning did not capture the full circulation of the storm, but did show winds of 30 mph on the east side of the center. Wind shear as diagnosed by the SHIPS model has increased to a moderate 10 - 15 knots, and is predicted to stay moderate through Friday. Ocean temperatures are 28 - 28.5°C, well above the threshold typically needed for a tropical storm to spin up. Water vapor satellite images show 98L is embedded in a moist environment, but there is dry air to the system's northwest. Given that the shear has now increased to the moderate level, this dry air may begin to hinder development on Wednesday. An analysis of upper level winds from the University of Wisconsin CIMMS group shows a pattern favorable for development, with an outflow channel open to both the north and south available to ventilate the storm and allow 98L to efficiently lift plenty of moisture to high levels.


Figure 2. Afternoon satellite image of 98L.

The latest 8 am EDT (12Z) runs of the computer models show either no development of 98L, or development of 98L into a tropical depression or weak tropical storm by Saturday. 98L's westward motion of 5 - 10 mph should bring the storm into the Lesser Antilles Islands by Saturday, though the models are not in strong agreement about the forward speed of the storm. The GFDL model brings 98L into the islands on Friday, while the HWRF model keeps the storm east of the islands through Sunday. If 98L takes a more west-northwesterly path through northern Lesser Antilles, which has been the preferred track for tropical systems this year, the disturbance should encounter high wind shear in excess of 20 knots due to strong upper-level winds out of the west. This shear should make it difficult for 98L to intensify as it moves though the islands. However, if 98L takes a more southerly path across Barbados, as predicted by the GFDL model, the storm will miss seeing the high shear area that lies over the northern islands, and the storm would have more opportunity to strengthen. The most likely scenario I see at this point is for 98L to be a weak tropical storm on Saturday as it moves through the Lesser Antilles--but there is more than the usual amount of uncertainty in both the track and intensity forecast. NHC gave the disturbance a 70% chance of developing into a tropical depression by Thursday in their 2 pm Tropical Weather Outlook.

September temperatures return to normal over the U.S.
The summer of 2011 was the second hottest in U.S. history, but September of 2011 is so far shaping up to be an average one for temperature. A series of cold fronts and cold-cored low pressure systems have moved southwards out of Canada this month, bringing typical amounts of cool air to the country. If you want to select dates for the start and end of the U.S. heat wave of 2011, the dates to pick would be May 20 - September 4. During the period May 20 - September 4, 2011, the number of daily record high temperatures at the 515 major airports in the U.S. exceeded the number of daily low temperature records every day but one. That's an astonishing 107 out of 108 days! Only July 15 had more record daily lows than highs during that 108-day period. I doubt one could find a similar stretch of days anytime in U.S. weather history where such a lopsided ratio of high temperature to low temperature records existed. For the 3-month summer period of June, July, and August, 2703 daily high temperature records were set, compared to 300 daily low temperature records--a ratio of 9-to-1. Not surprisingly, the summer of 2011 wound up as the hottest summer in 75 years in the U.S., and was only 0.1°F cooler than the all-time record hottest summer, during the Dust Bowl year of 1936. But so far this September, the ratio of high temperature records to low temperature records has been close to 1-to-1. There were 283 daily high temperature records set during the first sixteen days of September, and 246 low temperature records. Eight of the first sixteen days of September have seen the lows outnumber the highs, and eight have seen the highs outnumber the lows. The latest 2-week forecast from the GFS model shows a continuation of pretty normal weather over the U.S. for the rest of the month, and September temperatures will end up close to average.

Jeff Masters

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Quoting Skyepony:
Fresh WINDSAT of 98L. Little elongated but expecting an upgrade~ probably TS soon.



if recon was there it would already be one imo
Member Since: September 19, 2005 Posts: 2 Comments: 4110
i this saw the new WIS hurricane forcast and they upgrade the name storms from 18 too 21
Member Since: May 21, 2006 Posts: 5091 Comments: 114728
Quoting wxtropics1998:
what is next yrs predictions for hurricane season?



DOOM!
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FWIW...

WSI has upped their predicted number of named storms for this season up to 21 named storms.

To Whitney.
Member Since: July 6, 2010 Posts: 113 Comments: 31467
what is next yrs predictions for hurricane season?
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359. Skyepony (Mod)
Fresh WINDSAT of 98L. Little elongated but expecting an upgrade~ probably TS soon.

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Windsat , closed?
Member Since: April 29, 2007 Posts: 0 Comments: 7669
Quoting CybrTeddy:
Will you people STOP quoting BOGUSFORCASTAGAIN and all his other accounts??? Honestly, its getting on my nerves.. but not as much as the freak who keeps on making all the accounts, perma-banned should be allowed in this case. Its the same moron who's been posting and filling up my ignore. Here's the truth - BOGUSFORCASTAGAIN is some sad kid with nothing to do but to troll weatherunderground because he is either hurt still because he was a WU blogger himself but slipped up and got banned, or some kid who stumbled on a blog and decided to troll for his sick kicks and I refuse to be a part of them either way. I am sorry, but I've had enough of this. You're giving the kid ammunition, and he'll go away if you ignore him. If you all want him gone so bad, why do you give him food to just keep on coming back? I can understand the newer bloggers not understanding this, but in all honestly I don't understand why the older bloggers are doing this, even if I agree with what they're saying it has to end.

/rant off again.




well said
Member Since: May 21, 2006 Posts: 5091 Comments: 114728
Quoting TropicalAnalystwx13:


11PM PDT? That would make it 2AM EDT :)




you sure?
Member Since: May 21, 2006 Posts: 5091 Comments: 114728
Will you people STOP quoting BOGUSFORCASTAGAIN and all his other accounts??? Honestly, its getting on my nerves.. but not as much as the freak who keeps on making all the accounts, perma-banned should be allowed in this case. Its the same moron who's been posting and filling up my ignore. Here's the truth - BOGUSFORCASTAGAIN is some sad kid with nothing to do but to troll weatherunderground because he is either hurt still because he was a WU blogger himself but slipped up and got banned, or some kid who stumbled on a blog and decided to troll for his sick kicks and I refuse to be a part of them either way. I am sorry, but I've had enough of this. You're giving the kid ammunition, and he'll go away if you ignore him. If you all want him gone so bad, why do you give him food to just keep on coming back? I can understand the newer bloggers not understanding this, but in all honestly I don't understand why the older bloggers are doing this, even if I agree with what they're saying it has to end.

/rant off again.
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Quoting islander101010:
ninety nine is on my mind




Link
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Kinda old but almost there
Member Since: April 29, 2007 Posts: 0 Comments: 7669
Quoting JLPR2:


Eh.. you know what I mean. XD

Good call actually...its back in the outlook! (as so many of you have posted)

Quoting violet312s:


I'm in Durham. Not a local option :)

I don't see a problem with Greg Fishel (WRAL) myself, better than the meteorologists that blow up threats out of proportion in mainstream media (i.e. The Weather Channel...CNN Chad Myers to name a few)....
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Quoting Tazmanian:




there is no 11pm update on the two



they are has followed


2am 8am 2pm 8pm



no 5pm update no 11pm update un less they are TD TS or hurricane


11PM PDT? That would make it 2AM EDT :)
Member Since: July 6, 2010 Posts: 113 Comments: 31467
Quoting interstatelover7165:
Poll McPoll Time

What will Ninety-Eight-L be at Eleven?
Eighty Percent
Nintey
One Hundred
TD Sixteen

What will Ex-Ninety-Nine be at Eleven?
Zero
Ten
Twenty
Thirty
Invest Ninety Nine Again


both zilch!
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Quoting interstatelover7165:
Poll McPoll Time

What will Ninety-Eight-L be at Eleven?
Eighty Percent
Nintey
One Hundred
TD Sixteen

What will Ex-Ninety-Nine be at Eleven?
Zero
Ten
Twenty
Thirty
Invest Ninety Nine Again




there is no 11pm update on the two



they are has followed


2am 8am 2pm 8pm



no 5pm update no 11pm update un less they are TD TS or hurricane
Member Since: May 21, 2006 Posts: 5091 Comments: 114728
Quoting interstatelover7165:
Poll McPoll Time

What will Ninety-Eight-L be at Eleven?
Eighty Percent
Nintey
One Hundred
TD Sixteen

What will Ex-Ninety-Nine be at Eleven?
Zero
Ten
Twenty
Thirty
Invest Ninety Nine Again


1.) Lower - 70%

2.) Same - Near 0%
Member Since: July 6, 2010 Posts: 113 Comments: 31467
Quoting NCHurricane2009:
Evening,

Did everyone see Dr. M's outlook on the rest of the season yesterday? IMO...think that outlook is a bit too aggressive...I don't think we'll get to the "W" storm....

Also he mentioned GOM chances for a tropical cyclone have gone down I believe...but seemed to hint the east US coast? I don't think so...not this late in teh game...Caribbean and maybe Florida & Bermuda still in question though....


I completely agree!
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NHC a little hesitant to pull the trigger on 98L
Member Since: April 29, 2007 Posts: 0 Comments: 7669
Quoting WeatherNerdPR:
lol It won't give up.


It's a tiny happy little storm. Just twirling away like a girl in a ballerina costume. :)
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Quoting WeatherNerdPR:
lol It won't give up.


That's because its the remnants of Karen '07....Karen still lives!
Member Since: Posts: Comments:
Poll McPoll Time

What will Ninety-Eight-L be at Two?
Eighty Percent
Nintey
One Hundred
TD Sixteen

What will Ex-Ninety-Nine be at Two?
Zero
Ten
Twenty
Thirty
Invest Ninety Nine Again
Member Since: August 18, 2011 Posts: 0 Comments: 994
my WU e mail is being flooding with trolls tonight lol
Member Since: May 21, 2006 Posts: 5091 Comments: 114728
Quoting rkay1:
We all have different opinions, get over it.

That guy is "stressed" out from school according to his own account.
Member Since: May 26, 2011 Posts: 0 Comments: 1193
lol It won't give up.
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333. JLPR2
Quoting NCHurricane2009:


LOL...doesn't look happy to me....where's the eyes and mouth?


Eh.. you know what I mean. XD
Member Since: September 4, 2007 Posts: 7 Comments: 8500
i think we would have a TD if it was close enuff for recon data
Member Since: September 19, 2005 Posts: 2 Comments: 4110
Quoting NCHurricane2009:
Evening,

Did everyone see Dr. M's outlook on the rest of the season yesterday? IMO...think that outlook is a bit too aggressive...I don't think we'll get to the "W" storm....

Also he mentioned GOM chances for a tropical cyclone have gone down I believe...but seemed to hint the east US coast? I don't think so...not this late in teh game...Caribbean and maybe Florida & Bermuda still in question though....

lol, I thought this prediction of 7 was a tad too low.

Remember, we're in a La Nina year, which favors really active late seasons.
Member Since: July 6, 2010 Posts: 113 Comments: 31467
Quoting JLPR2:
I wasn't expecting ex-99L to look so happy.


LOL...doesn't look happy to me....where's the eyes and mouth?
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Evening,

Did everyone see Dr. M's outlook on the rest of the season yesterday? IMO...think that outlook is a bit too aggressive...I don't think we'll get to the "W" storm....

Also he mentioned GOM chances for a tropical cyclone have gone down I believe...but seemed to hint the east US coast? I don't think so...not this late in teh game...Caribbean and maybe Florida & Bermuda still in question though....
Member Since: Posts: Comments:
327. JLPR2
Quoting TropicalAnalystwx13:
How do they get that the center isn't well-defined?


I'm crossing my fingers ASCAT catches 98L.
Member Since: September 4, 2007 Posts: 7 Comments: 8500
We deserve a quiet 2nd half of the season and we will get it.
Member Since: May 26, 2011 Posts: 0 Comments: 1193
Quoting TropicalAnalystwx13:
How do they get that the center isn't well-defined?

I know right?
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Quoting violet312s:


I'm in Durham. Not a local option :)


ah, lol.
Member Since: July 6, 2010 Posts: 113 Comments: 31467
Quoting TropicalAnalystwx13:


Yeah.

I'd switch from WRAL to WECT though, much better IMO ;)


I'm in Durham. Not a local option :)
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another circle at 8:00
Member Since: September 19, 2005 Posts: 2 Comments: 4110
How do they get that the center isn't well-defined?
Member Since: July 6, 2010 Posts: 113 Comments: 31467


When the fronts come blasting through the gom that will cool the water and the season will get shut down in the gom and then caribbean
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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