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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465. Neapolitan
12:37 AM GMT on September 21, 2011
Quoting MiamiHurricanes09:
Dvorak satellite estimates still yield the classification of 16L.

Unless it fades away overnight, I'd say it'll be classified within the next 12 hours.
Member Since: November 8, 2009 Posts: 4 Comments: 13742
464. TropicalAnalystwx13
12:36 AM GMT on September 21, 2011
Quoting Tazmanian:




i did not say any thing about a pine hole eye in 96E


i this said 96E has a eye


Its a nice pinhole eye too! Good eye!
Member Since: July 6, 2010 Posts: 113 Comments: 32706
463. TropicalAnalystwx13
12:35 AM GMT on September 21, 2011
Quoting MiamiHurricanes09:
Dvorak satellite estimates still yield the classification of 16L.


The NHC has reverted back to their normal selves.

They classified Jose, so why not this? This should be Ophelia!
Member Since: July 6, 2010 Posts: 113 Comments: 32706
462. Tazmanian
12:35 AM GMT on September 21, 2011
Quoting DiddyVort:
Good call Taz....96E has a pin-hole eye man!






i did not say any thing about a pine hole eye in 96E


i this said 96E has a eye
Member Since: May 21, 2006 Posts: 5091 Comments: 115437
461. MiamiHurricanes09
12:34 AM GMT on September 21, 2011
Dvorak satellite estimates still yield the classification of 16L.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
460. JLPR2
12:34 AM GMT on September 21, 2011
Quoting BDADUDE:
You are infatuated with 99l dude. Maybe it will do something in the end.


Well duh! it's just to our east. :)
Member Since: September 4, 2007 Posts: 7 Comments: 8747
459. Chicklit
12:33 AM GMT on September 21, 2011
98L is pretty awesome, actually.
very understated.
LinkWVLoopCATL
LinkRainbowloopCATL
Member Since: July 11, 2006 Posts: 14 Comments: 11410
457. FrankZapper
12:31 AM GMT on September 21, 2011
I saw where Hot Pockets has a new offering. Hot crow with mushrooms. A "quick tasty treat" for the Blogosphere".
Member Since: May 26, 2011 Posts: 0 Comments: 1193
456. MelbourneTom
12:31 AM GMT on September 21, 2011
Quoting Chicklit:
449. MelbourneTom 12:27 AM GMT on September 21, 2011 +1
98L structure is a bit odd.

Nice presentation, Tom.


Thanks, that's from the Navy.
Member Since: June 2, 2007 Posts: 0 Comments: 619
455. Neapolitan
12:31 AM GMT on September 21, 2011
ATCF says no change in strength. As MelbourneTom said in #449, 98L still looks a "bit odd":

AL, 98, 2011092100, , BEST, 0, 120N, 396W, 30, 1007, LO, 0, , 0, 0, 0, 0,
Member Since: November 8, 2009 Posts: 4 Comments: 13742
454. BDADUDE
12:30 AM GMT on September 21, 2011
Quoting WeatherNerdPR:

Look at ex-99L's vorticity! XD
You are infatuated with 99l dude. Maybe it will do something in the end.
Member Since: September 3, 2008 Posts: 0 Comments: 605
453. Chicklit
12:30 AM GMT on September 21, 2011
449. MelbourneTom 12:27 AM GMT on September 21, 2011 +1
98L structure is a bit odd.

Nice presentation, Tom.
Member Since: July 11, 2006 Posts: 14 Comments: 11410
452. wxtropics1998
12:29 AM GMT on September 21, 2011
Quoting scooster67:

Technicalities. :)


an "eye" is a meteorological term for a hurricane. Not just a break in convection(which Taz incorrectly says). I could technically say there were many "eyes" today in the tropics because of a break in convection
Member Since: September 6, 2011 Posts: 0 Comments: 22
451. Chicklit
12:29 AM GMT on September 21, 2011
Member Since: July 11, 2006 Posts: 14 Comments: 11410
Quoting JLPR2:
there we go!

Look at ex-99L's vorticity! XD
Member Since: Posts: Comments:
98L structure is a bit odd.

Member Since: June 2, 2007 Posts: 0 Comments: 619
Quoting wxtropics1998:


no it doesnt.

Technicalities. :)
Member Since: Posts: Comments:
447. JLPR2
This increase in vort signature is ridiculous, CIMMS must have been glitching earlier.

I mean, come on! A reflection all the way to 200mb level?
Member Since: September 4, 2007 Posts: 7 Comments: 8747


LinkLOOP
Member Since: July 11, 2006 Posts: 14 Comments: 11410
445. SLU
CIMSS-UW vorticity analysis show that the strongest vorticity is at 11n 40w near the deep convection.
Member Since: Posts: Comments:
Quoting Tazmanian:
96E has a eye




no it doesnt.
Member Since: September 6, 2011 Posts: 0 Comments: 22
96E has a eye


Member Since: May 21, 2006 Posts: 5091 Comments: 115437


98L is taking the leisurely route across the Atlantic
Member Since: July 11, 2006 Posts: 14 Comments: 11410
440. JLPR2
there we go!
Member Since: September 4, 2007 Posts: 7 Comments: 8747
Quoting CybrTeddy:
Those points, FrankZapper, imo are about as good milk 3 years after its expiration date.

He has done absolutely nothing to back up his points and has reverted to downcasting, a term I tend to use lightly unless we're generalizing. He's been banned again and again, because he continues to make those points.
The pattern would have to change significantly for 98 to have a chance at being a land shark.

And the blog right now is sorely in need of new blood to make up for recent losses.
Member Since: May 26, 2011 Posts: 0 Comments: 1193
Quoting Tazmanian:



no its not its still dead in other words 99L is still EX 99L

Technicalities! :)
Member Since: Posts: Comments:
436. JLPR2
Quoting Skyepony:
Orange wind arrows indicate that the Variational Quality Control flag is set, i.e. the Wind Vector Cell is spatially inconsistent. An orange dot means that the KNMI Quality Control Flag is set. More information on the quality flags can be obtained from the ASCAT Wind Product User Manual.


Ah I see, it is similar to the black arrows on the other version.
Member Since: September 4, 2007 Posts: 7 Comments: 8747




Which one is better?
Member Since: July 6, 2010 Posts: 113 Comments: 32706
All current and future forecasters be warned. This could be you on trial for failing to predict a natural disaster...

http://www.cnn.com/2011/09/20/world/europe/italy- quake-trial/index.html?hpt=hp_t2

Member Since: Posts: Comments:
432. Skyepony (Mod)
Orange wind arrows indicate that the Variational Quality Control flag is set, i.e. the Wind Vector Cell is spatially inconsistent. An orange dot means that the KNMI Quality Control Flag is set. More information on the quality flags can be obtained from the ASCAT Wind Product User Manual.
Member Since: Posts: Comments:
Quoting JLPR2:


Forgot what orange arrows meant... stronger winds?

ASCAT sucks! LOL! Caught just the eastern side.


I have NEVER been on this blog and seen a good ASCAT pass...NEVER...LOL
Member Since: Posts: Comments:
428. SLU
Quoting CybrTeddy:


ASCAT however, different story.. latest past showed what appears to me to have tightened up considerably since the last pass. That could lead to an upgrade, but I've seen much more loosely defined systems this year get upgraded.. one with 12 different vorts *TD Emily off Florida*.


Remember those systems with poor circulations that the NHC named (EMILY, IRENE, MARIA) were all threatening land and were all generating winds of tropical storm force as per the RECON even with weak circulations. My experience over the years has taught me that the NHC will never renumber an invest 1400 miles out in the Atlantic without 100% proof of it meeting all the conditions required. That's why they kept it at 70% all day too when it deserved more.
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427. JLPR2


Forgot what orange arrows meant... stronger winds?

ASCAT sucks! LOL! Caught just the eastern side.
Member Since: September 4, 2007 Posts: 7 Comments: 8747
Quoting NCHurricane2009:


I think Ophelia should have been retired 'cause that shingle....


No, not the shingle.

If it needs to be retired, its because of that raindrop.

Now that was a raindrop, I tell you!

Gosh..What a horrible raindrop.
Member Since: July 6, 2010 Posts: 113 Comments: 32706
hey kids! Time to do your homework!

Member Since: September 6, 2011 Posts: 0 Comments: 22

419. Tazmanian 8:09 PM EDT on September 20, 2011

Taz please dont quote him i think he has friends in low places
Member Since: Posts: Comments:
Those points, FrankZapper, imo are about as good milk 3 years after its expiration date.

He has done absolutely nothing to back up his points and has reverted to downcasting, a term I tend to use lightly unless we're generalizing. He's been banned again and again, because he continues to make those points.
Member Since: July 8, 2005 Posts: 259 Comments: 24550
Quoting MississippiWx:


Geez, what did that shingle do to you?


I think Ophelia should have been retired 'cause that shingle....
Member Since: Posts: Comments:
Quoting FrankZapper:
Come on Teddy. There is nothing wrong with a spirited debate about the tropics. And the kid has some good points.




you got too be jokeing
Member Since: May 21, 2006 Posts: 5091 Comments: 115437
*Ahem*
Member Since: Posts: Comments:
Quoting MississippiWx:


:-)

Just kidding.


The shingle didn't do anything to me btw, lol.
Member Since: July 6, 2010 Posts: 113 Comments: 32706

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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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