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 TomTaylor:

is that a joke?


I don't think he is really cocky, but I do occasionally get that vibe coming off his posts. No offense to him, I have plenty of flaws my self, just a casual observation.
speaking of flaws, there's a nice typo.
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614. JLPR2
Well I'll be on and off for awhile. Got to do some homework and an essay. :\
Member Since: September 4, 2007 Posts: 7 Comments: 8747
Quoting Tazmanian:
if you stan under a tree you be safe from lighting
Wrong, that is the worse thing you can do other than be on or in the water.
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First of all, this Elenin crap is just that....crap.

Second, if there is a closed surface low, it is quite elongated. Notice the "well defined" part of the NHC discussion.
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611. JLPR2
The blog had a little burst of activity. This place has been a ghost town the last several days, comparing it to the usual activity.

Also, 98L still has some work to do, needs deep convection, shallow convection just doesn't do it.
Member Since: September 4, 2007 Posts: 7 Comments: 8747
Quoting MiamiHurricanes09:
If a renumber were to occur, anticipate one in 15-20 minutes.

I'll honestly be surprised if we don't get Ophelia at 11p.m.
Hard to say, although since it's currently at 70%, I don't think they will jump to TD status.

Latest ASCAT has winds from NE to SW, which means it's either open or a very elongated, weakly closed circulation. Not enough evidence to tell which it is at the moment.
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Quoting TropicalAnalystwx13:


Nooo...I do not recommend that.




i no i this wanted too see what evere one would say am this like mass with you all some time lol
Member Since: May 21, 2006 Posts: 5091 Comments: 115456
Quoting Tazmanian:
if you stan under a tree you be safe from lighting


Nooo...I do not recommend that.
Member Since: July 6, 2010 Posts: 113 Comments: 32860
Quoting jrweatherman:


Drakeon is a smart but also really cocky. thats why I like him.
is that a joke?


I don't think he is really cocky, but I do occasionally get that vibe coming off his posts. No offense to him, I have plenty of flaws my self, just a casual observation.

Quoting JLPR2:


Neither enough evidence to call it open since we are missing a little more than half of the system.

Now look what the crappy ASCAT started. XD LOL!
Well I guess you're right. If we are allowed to change stances, I believe there is not enough evidence to determine either way.
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CAPE CANAVERAL, Florida (AP) — NASA scientists are doing their best to tell us where a plummeting six-ton satellite will fall later this week. It's just that if they're off a little bit, it could mean the difference between hitting Florida or landing on New York. Or, say, Iran or India.

Pinpointing where and when hurtling space debris will strike is an imprecise science. For now, scientists predict the earliest it will hit is Thursday U.S. time, the latest Saturday. The strike zone covers most of Earth.
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Quoting BahaHurican:
Hey.... do u have internet back at ur house yet?


Yes....

and then last Friday I lost it (DSL that is) for 24 hours
...am a couple pages behind now and reading up to current.
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Quoting TomTaylor:
Well if I am saying there isn't enough evidence to call it closed and he comes along saying it's undoubtedly closed, how is that any different than saying he undoubtedly (in his opinion) believes I am wrong?

Regardless, it came off as arrogant even if that wasn't his intent.

Anyway, enough bickering, I guess I'll get out of here and go do some hw or something.


Didn't you just get here?
Member Since: July 6, 2010 Posts: 113 Comments: 32860
Quoting MiamiHurricanes09:
If a renumber were to occur, anticipate one in 15-20 minutes.

I'll honestly be surprised if we don't get Ophelia at 11p.m.


Prepare to be surprised.

Or not.
Member Since: July 6, 2010 Posts: 113 Comments: 32860
If a renumber were to occur, anticipate one in 15-20 minutes.

I'll honestly be surprised if we don't get Ophelia at 11p.m.
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Quoting JLPR2:



You took it out of context, he said that for him it 98L undoubtedly has a closed LLC and that's his opinion.

Just like you seem pretty sold on the idea that it is open.

Be careful, calling him arrogant could be viewed by Admins as a personal attack.
Well if I am saying there isn't enough evidence to call it closed and he comes along saying it's undoubtedly closed, how is that any different than saying he undoubtedly (in his opinion) believes I am wrong?

Regardless, it came off as arrogant even if that wasn't his intent.

Anyway, enough bickering, I guess I'll get out of here and go do some hw or something.
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598. JLPR2
Quoting TomTaylor:
My opinion is that there is doubt about it being closed and that at the time of the latest ASCAT pass, there was not enough evidence to call it closed.

At the moment, or by the next OSCAT pass, it may very well be closed, as it is very close on the last ASCAT pass. To reiterate, however, I don't believe there is enough evidence to call it closed based of that last ASCAT pass.


Neither enough evidence to call it open since we are missing a little more than half of the system.

Now look what the crappy ASCAT started. XD LOL!
Member Since: September 4, 2007 Posts: 7 Comments: 8747
Quoting TomTaylor:
If only we had the funds for more satellites...


The return of QuikScat would be great.
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Quoting TomTaylor:
If only we had the funds for more satellites...


QuikScat.
Member Since: July 6, 2010 Posts: 113 Comments: 32860
Quoting TropicalAnalystwx13:
Well, it doesn't matter. If its open, its open. If its closed, its closed.

The world may never know..
If only we had the funds for more satellites...
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594. JLPR2
Quoting TomTaylor:
I never said you needed to go back to lurking.

But yes, saying I am undoubtedly wrong is arrogant. Especially in the absence of any data to confirm your conclusion. You are assuming something, not observing.



You took it out of context, he said that for him 98L undoubtedly has a closed LLC and that's his opinion.

Just like you seem pretty sold on the idea that it is open.

Be careful, calling him arrogant could be viewed by Admins as a personal attack.
Member Since: September 4, 2007 Posts: 7 Comments: 8747
Well, it doesn't matter. If its open, its open. If its closed, its closed.

The world may never know..
Member Since: July 6, 2010 Posts: 113 Comments: 32860
with her distance from land NHC has plenty of time to upgrade
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Quoting TomTaylor:
I never said you needed to go back to lurking.

But yes, saying I am undoubtedly wrong is arrogant. Especially in the absence of any data to confirm your conclusion. You are assuming something, not observing.


Drakeon is a smart but also really cocky. thats why I like him.
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Quoting JLPR2:


Ok. We cant be 100% sure if it is closed or open since this is just a partial pass. So we are going by opinion. yours is that it is open and Drak's and mine that it is closed.
I hope Oceanscat gives us a nice view of the system to solve this dilemma.

My opinion is that there is doubt about it being closed and that at the time of the latest ASCAT pass, there was not enough evidence to call it closed.

At the moment, or by the next OSCAT pass, it may very well be closed, as it is very close on the last ASCAT pass. To reiterate, however, I don't believe there is enough evidence to call it closed based of that last ASCAT pass.
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Quoting Tropicsweatherpr:


That was made at 4:15 PM EDT.


The same time as the Windsat pass, was intended to show the lack of convection where the WindSat indicated a circulation.
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Quoting markot:
what are you talking about threat to bermuda, it is going west into the carribean...


Most experts are indicating is that it is going to be somewhere in the NE Caribbean and then turn north just like the other storms. That would put Bermuda in a potential path. The GFDL is an outlier but it has been an outlier for many of the storms this year.
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Quoting unknowncomic:
Has there been any good jokes about the next storm"s name?
I HOphelia the NHC declares Ninety-Eight-L Soon.
Member Since: August 18, 2011 Posts: 0 Comments: 994
Quoting Drakoen:
I'm arrogant? LOL. I need to go back to lurking.
I never said you needed to go back to lurking.

But yes, saying I am undoubtedly wrong is arrogant. Especially in the absence of any data to confirm your conclusion. You are assuming something, not observing it. Big difference.
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Quoting all4hurricanes:
This weather blog has jumped the gun on many tropical storms this year I don't think the NHC will upgrade it anytime soon




i disagree it has TS winds and a closed low the nhc is this waiting for the right time
Member Since: May 21, 2006 Posts: 5091 Comments: 115456
584. JLPR2
Quoting TomTaylor:
It will soon, if it does not already. At the moment, it's impossible to say (based off evidence, not ego) that this is a closed circulation.


Ok. We cant be 100% sure if it is closed or open since this is just a partial pass. So we are going by opinion. Yours is that it is open and Drak's and mine that it is closed.
I hope Oceanscat gives us a nice view of the system to solve this dilemma.

Member Since: September 4, 2007 Posts: 7 Comments: 8747
?
Member Since: May 26, 2011 Posts: 0 Comments: 1193
Quoting Drakoen:
I'm arrogant? LOL. I need to go back to lurking.


Incorrect.
Member Since: July 6, 2010 Posts: 113 Comments: 32860
I'm arrogant? LOL. I need to go back to lurking.
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Quoting TropicalAnalystwx13:


No, there really isn't.

I'd explain my reasoning but I'm too lazy :P
Well if you ever decide to take the time, I'm here waiting.

I see no reason why this can't have been an inverted trough (as opposed to a closed circulation) at the time of the pass.

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Quoting nrtiwlnvragn:


In my eyes in needs to develop convection where WindSat indicated a possible circulation.





Since designation is a subjective decision, it will always be "discussed"


That was made at 4:15 PM EDT.
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98 seems to be becoming more disorganized.
Member Since: May 26, 2011 Posts: 0 Comments: 1193
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Quoting nrtiwlnvragn:


In my eyes in needs to develop convection where WindSat indicated a possible circulation.





Since designation is a subjective decision, it will always be "discussed"


Can't disagree there.
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Quoting Drakoen:


You are undoubtedly confused on reading ASCAT passes. You're are using a different pass at a time when the structure of 98L was different and trying to prove a point about a current pass that is invalid.
No I'm illustrating a point.
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Quoting markot:
what are you talking about threat to bermuda, it is going west into the carribean...
No way. Its following Katia so will be no threat to Bermuda.
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Quoting scooster67:


How low? 16n?

If 98L can stay below 15N she has a chance of running the gauntlet.
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Quoting hurricanejunky:
Vorticity looks great. Does it have a well defined closed LLC yet?
It will soon, if it does not already. At the moment, it's impossible to say (based off evidence, not ego) that this is a closed circulation.
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Wake me up when Ninety-eight is classified. seriously.i'm getting bored.
Member Since: August 18, 2011 Posts: 0 Comments: 994
This weather blog has jumped the gun on many tropical storms this year I don't think the NHC will upgrade it anytime soon
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Quoting TomTaylor:
I lol'd.

Undoubtedly?

Let's draw a line through the last ASCAT pass to pretend that the pass was an incomplete pass like the current one and see what we get.






Look closely and we have SW to ENE winds. Not quite as complete of a circulation as the current pass, but if you look at the rest of the circulation it is clearly open.

There is definitely doubt that this is closed, Drakoen.


You are undoubtedly confused on reading ASCAT passes. You're are using a different pass at a time when the structure of 98L was different and trying to prove a point about a current pass that is invalid.
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Quoting WxLogic:


Well, quite conclusive of a TS in my eyes. I was expecting it to be a TD by 8PM but we'll see if it makes it by 2AM, but I would lean towards a TS than a TD.


In my eyes in needs to develop convection where WindSat indicated a possible circulation.





Since designation is a subjective decision, it will always be "discussed"
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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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