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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Member Since: July 15, 2006 Posts: 175 Comments: 54858
JASON, er, MODELSNEVERRIGHT - not sure why you'd want to waste your time here but you can count on getting removed shortly...it never fails with trolls of your inflammation level.
Member Since: August 28, 2006 Posts: 6 Comments: 2899
Yep, its a high schooler.

Probably in 11th or 12th grade.
Member Since: Posts: Comments:
We have to get used to it.....

From time to time one of a group of Trolls are going to infest the blog... and this repeats and is what we have seen.... So we should stay calm.... nothing new in them...

They will come with different approaches and attitudes...

1. Models don't work
2. Season ended
3. All invests are Fish storms
4. That will turn into a CAT 5 and I wish it will kill my area; or kill your area...
5. You are a bunch of #$%##
6. Post unapropiate dirty photos
7. USE THE CAPS IN EVERY POST
8. Send emails to bloggers
And the list goes on....

SO WHAT!!! THEY ARE JUST ...... trolls

Admin will take chage of them....
But saddly....they will return....
Member Since: August 2, 2010 Posts: 21 Comments: 9874
Quoting will40:


i agree Taz and i hope he does


it was a joke...lighten up...
Member Since: August 28, 2006 Posts: 6 Comments: 2899
Quoting KEEPEROFTHEGATE:
only thing over is me all over you


That sounds bad on so many levels...
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Major hurricane dealing with dry air...Should weaken it a category before landfall...Down to Cat. 2.

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<
Member Since: July 15, 2006 Posts: 175 Comments: 54858
Oh well...
Member Since: August 28, 2006 Posts: 6 Comments: 2899
Quoting Tazmanian:




injoy the ban thats how P541 got ban


i agree Taz and i hope he does
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Quoting hurricanejunky:


Could it be????





they will most likey ban ban you for that. Thats how P541 got ban
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Quoting scott39:
Does anyone else "feel" like 98L is being underestimated, in regards to its future strength?
I defintley agree.
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Quoting victoriahurricane:
Whack a Troll


LOL. Like that one!
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Quoting koolkiddvc:
I notice that WU has 98L at 12 North but Storm pulse still has the system down at 10.8 north, it has more than a degree south of the WU points in the past few days...can anyone explain this?

Wunderground is more up to date.
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Whack a Troll, Admin time for round 3.
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139. DFWjc
Quoting TropicalAnalystwx13:


I don't think your username is TropicalAnalystwx13 :P


Oh right right..:P
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Member Since: Posts: Comments:
Quoting kwgirl:
Good night all. Have fun. It looks like the trolls, er.. kids are out of school.


Hey KW Girl. Don't let 'em drive ya out. Stop on over when you get a chance...
Member Since: August 28, 2006 Posts: 6 Comments: 2899
Quoting DFWjc:


Well If Taz didn't stop me, i was going to do worse...


I don't think your username is TropicalAnalystwx13 :P
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some of you just loveeeeeeeeeeeeeeeeeeeeee to feed them that is very obivious
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132. DFWjc
Quoting hurricanejunky:


You're name calling? Wow...


Well If Taz didn't stop me, i was going to do worse...
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Quoting hurricanejunky:


You're name calling? Wow...


Its different.. :P
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Endurance is patience concentrated.
Thomas Carlyle

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Quoting TropicalAnalystwx13:


Idiot...

That's all I have to say, back to weather (:


You're name calling? Wow...
Member Since: August 28, 2006 Posts: 6 Comments: 2899
Quoting DFWjc:


Not sad, weather happens around the planet 24/7, and I'm going to read what every has to say and still form my own opinion, that's why we live in such a great nation as we do...




and stop Quoteing him plzs
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Err...do you want to run it by me why you would want to troll a blog?
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123. DFWjc
Quoting MODELSNEVERRIGHT:


Not sad, weather happens around the planet 24/7, and I'm going to read what every has to say and still form my own opinion, that's why we live in such a great nation as we do...
Member Since: Posts: Comments:
121. DFWjc
Quoting Tazmanian:





i would stop be for you get ban


Taz as much as I respect you, I'll quit for now... but in the future my patience may not be availible...
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Quoting DFWjc:



I'm going to have to agree to disagree...









i would stop be for you get ban
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Stop quoting the troll, please
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Quoting Gearsts:
Alot of shear north, dry air west and down MJO... No
Wind shear is its biggest obstacle. If it takes the more Southern track the GFDL is currently showing,more developement is likely. GFDL is why I have some doubt about a more N path for now.
Member Since: June 13, 2009 Posts: 0 Comments: 6891

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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.