99L a threat to develop; damage from Typhoon Megi still largely unknown

By: Dr. Jeff Masters , 1:38 PM GMT on October 19, 2010

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Heavy thunderstorm activity has increased and grown more organized this morning over the southwestern Caribbean between Honduras and the Cayman Islands, in association with a tropical disturbance (Invest 99L). The storm is bringing heavy rain to the Cayman Islands; two inches has fallen so far this morning at Savannah on Grand Cayman Island. Recent satellite imagery shows that 99L has some rotation, and the winds on the northeast coast of Honduras at Puerto Lempira have shifted to the west-northwest, implying that 99L may be developing a surface circulation. Wind shear is a moderate 10 - 20 knots, which is low enough to allow some slow development. Water vapor satellite loops reveal that the atmosphere in the Western Caribbean is moist enough to support development, and the waters beneath are plenty warm, at 29°C. The latest SHIPS model forecast predicts that wind shear over the Western Caribbean will mostly remain in the moderate range, 10 - 20 knots, for the remainder of the week. The current north-northwest motion of 99L should continue until Wednesday, when a strong ridge of high pressure is forecast to build in, forcing 99L to the south or west. However, steering currents will be weak Wednesday through Friday, making it difficult to predict where 99L may wander to. The only models that develop 99L are the GFDL and HWRF. The GFDL model predicts that 99L will spend enough time over water to develop into a hurricane, and brings the storm to the coast of Mexico's Yucatan Peninsula on Sunday morning. The HWRF model has 99L making landfall over Honduras late this week, before the storm has a chance to develop into a hurricane. NHC is giving 99L a 40% chance of developing into a tropical depression by Thursday. I believe the odds are higher, near 60%. The Hurricane Hunters are on call to investigate 99L this afternoon.


Figure 1. Morning satellite image of Invest 99L.

Damage from Super Typhoon Megi still largely unknown
The power is still out and communications are down over the majority of the northern portion of the Philippines' Luzon Island blasted by Typhoon Megi yesterday, so the extent of the destruction wrought by the great storm is still largely unknown. Preliminary news reports indicate that at least 10 people died, and the northern Philippine province of Isabela suffered severe damage. Megi hit Luzon on Monday morning at 3:30 UTC as a Category 5 super typhoon with sustained winds of 165 mph and a central pressure of 914 mb. Baguio near the west coast of northern Luzon received 7.72" of rain from the storm, and many mountainous regions likely received over a foot of rain.


Figure 2. Rainfall rates in excess of 1 inch per hour (orange colors) were observed by the polar-orbiting F-18 satellite in association with Megi at 00:40 UTC October 19, 2010. Image credit: Navy Research Lab, Monterey.

Passage over Luzon Island destroyed Megi's eyewall and inner core region, and the storm compensated by expanding and intensifying the portions of its circulation that were over water. Now that its center is back over water in the South China Sea, Megi has re-developed its inner core and has built a formidable new eyewall. At the same time, Megi has been able to maintain its larger size, and is now a much larger typhoon than when it hit the Philippines. This is similar to what happened to Hurricane Ike in 2008 when it passed over Cuba, and helped give Ike a very destructive storm surge when it came ashore over Texas. Wind shear is a low 5 - 10 knots over Megi, and the waters of the South China sea have a very high total heat content to great depth, so Megi should be able to intensify into a very dangerous Category 4 storm by Thursday. The larger size of Megi means that it will be able to deliver a significant storm surge in excess of ten feet to the coast of China of Friday or Saturday, when the storm is expected to make landfall near Hong Kong. As the storm approaches the coast on Friday, wind shear is expected to rise to the moderate or high range, and the total heat content of the ocean will drop significantly, so some weakening is to be expected. Still, Megi will probably hit China as a major Category 3 typhoon,bringing a significant storm surge, high winds, and widespread torrential rains that will likely make this a multi-billion dollar disaster for China.

"Daily Downpour" airing this afternoon
Our live Internet radio show, "Daily Downpour", will be airing today at 4pm EDT. The call in number is 415-983-2634, or you can post a question to broadcast@wunderground.com. You can tune in at http://www.wunderground.com/wxradio/wubroadcast.h tml, and I'll be discussing the latest info on Invest 99L with hosts Shaun Tanner and Tim Roche.

Jeff Masters

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1325. toddbizz
3:29 PM GMT on October 20, 2010
ok...I was watching the weather channel tropical update last night at 9:50 PM EST he stated that there's no chance of 99L coming near CONUS SFL...any responses...from you guys...they seemed pretty confident that this storm will not affect SFL...period the end...
Member Since: September 28, 2010 Posts: 0 Comments: 88
1324. utilaeastwind
2:25 PM GMT on October 20, 2010
Latest RGB loop shows a southward motion could be underway.
Member Since: October 12, 2007 Posts: 0 Comments: 192
1323. hcubed
2:06 PM GMT on October 20, 2010
Quoting CyclonicVoyage:



Mid-October storms in the NW Caribbean should have all Floridians on guard. It's nearly a no-brainer.


Can we use the words "FLstormwarning" and "no-brainer" in the same posting?
Member Since: May 18, 2007 Posts: 289 Comments: 1639
1322. SNOWARMER
1:39 PM GMT on October 20, 2010
Quoting aprinz1979:


LOL hadn't see this since August I think

WE ARE ALL DOOM!!! LOL
Here in Houston we have been DOMED since the early '60's LOL
Member Since: February 10, 2010 Posts: 0 Comments: 30
1321. scott39
1:36 PM GMT on October 20, 2010
Quoting IKE:
Water vapor in a loop...boxing itself in a corner?
Move like a butterfly sting like a bee!
Member Since: June 13, 2009 Posts: 0 Comments: 6912
1320. cat5hurricane
1:34 PM GMT on October 20, 2010
Quoting CyclonicVoyage:


06Z GFDL is not forecasting any significant development until 24-48 hrs. Analysis is pretty good and I think it's handling the current tracking well.


We'll see by then. It sure has time and conditions aloft on it's side to develop into something.
Member Since: August 17, 2010 Posts: 21 Comments: 6939
1319. Neapolitan
1:34 PM GMT on October 20, 2010
NEW BLOG
Member Since: November 8, 2009 Posts: 4 Comments: 13731
1318. scott39
1:33 PM GMT on October 20, 2010
A naked LLC does not make a dead 99L! Dangit Jim Give it time! LOL
Member Since: June 13, 2009 Posts: 0 Comments: 6912
1317. CyclonicVoyage
1:31 PM GMT on October 20, 2010
Quoting cat5hurricane:

I think instead as the shear begins to relax the convection should re-align back over the LLC.


06Z GFDL is not forecasting any significant development until 24-48 hrs. Analysis is pretty good and I think it's handling the current tracking well.

Member Since: January 30, 2010 Posts: 0 Comments: 3259
1316. IKE
1:29 PM GMT on October 20, 2010
Water vapor in a loop...boxing itself in a corner?
Member Since: June 9, 2005 Posts: 23 Comments: 37860
1315. cat5hurricane
1:29 PM GMT on October 20, 2010
Quoting pottery:

Shucks!!
I was looking for some action...
Well, I have things to do, and if you guys are going to keep agreeing with each other, I may as well leave.....

heheheheh

It won't last Pottery. lol
Member Since: August 17, 2010 Posts: 21 Comments: 6939
1314. Orcasystems
1:28 PM GMT on October 20, 2010
Quoting pottery:

Shucks!!
I was looking for some action...
Well, I have things to do, and if you guys are going to keep agreeing with each other, I may as well leave.....

heheheheh


31 years today Pottery... I am starting to get old like you.
Member Since: October 1, 2007 Posts: 81 Comments: 26512
1313. scottsvb
1:28 PM GMT on October 20, 2010
LLC has been well defined for the past 24hrs..

I dont think it looks better than Nicole. Not until T-Storms fire closer to the center.. infact 99L looked better 12hrs ago than right now.

Still this system has 2 possibilities. 1, the shear lessons over the next 12-24hrs and T-Storms fire over the center.. if this happens.. This will be upgraded to probably a Tropical Storm by Thurs. If it takes until Sat-Sun.. the LLC will move with the LLFlow SSW into Honduras and Belize by Sunday. If it gets its act together though again in the next day or so.. a stronger system will keep it stationary and then move it more W and WNW with the midlevel flow around a strong ridge over Florida and the Bahamas. Next 24-36hrs may determine this track thru the weekend.
Member Since: January 22, 2006 Posts: 0 Comments: 1723
1311. aprinz1979
1:28 PM GMT on October 20, 2010
Quoting scott39:
DOOM!!!!


LOL hadn't see this since August I think

WE ARE ALL DOOM!!! LOL
Member Since: October 5, 2010 Posts: 0 Comments: 269
1310. scott39
1:27 PM GMT on October 20, 2010
Didnt the NHC say earlier that wind shear for 99l will become favorable soon?
Member Since: June 13, 2009 Posts: 0 Comments: 6912
1309. Orcasystems
1:27 PM GMT on October 20, 2010



Member Since: October 1, 2007 Posts: 81 Comments: 26512
1308. pottery
1:26 PM GMT on October 20, 2010
Quoting GeoffreyWPB:


No argument here.

Shucks!!
I was looking for some action...
Well, I have things to do, and if you guys are going to keep agreeing with each other, I may as well leave.....

heheheheh
Member Since: October 24, 2005 Posts: 0 Comments: 24789
1307. cat5hurricane
1:26 PM GMT on October 20, 2010
Quoting 7544:
they will relocate the center latter on today maybe further east imo watch

I think instead as the shear begins to relax the convection should re-align back over the LLC.
Member Since: August 17, 2010 Posts: 21 Comments: 6939
1306. CyclonicVoyage
1:25 PM GMT on October 20, 2010
At 13:13:30Z (last observation), the observation was 334 miles (538 km) to the WSW (255°) from Key West, FL, USA.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
1305. Stormchaser2007
1:25 PM GMT on October 20, 2010
Visible reveals a rather weak circulation a good deal away from the convection.




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1304. IKE
1:25 PM GMT on October 20, 2010
Water vapor....

Member Since: June 9, 2005 Posts: 23 Comments: 37860
1303. 7544
1:24 PM GMT on October 20, 2010
they will relocate the center latter on today maybe further east imo watch
Member Since: May 6, 2007 Posts: 0 Comments: 6874
1302. Neapolitan
1:24 PM GMT on October 20, 2010
Quoting scott39:
Will that change?

Unless something occurs that is completely against the laws of physics, fluid dynamics, climatology, and meterology, yes, it will change.
Member Since: November 8, 2009 Posts: 4 Comments: 13731
1301. cat5hurricane
1:24 PM GMT on October 20, 2010
Quoting PensacolaDoug:



Badly sheared system but the circulation at the lower levels is as defined as it's ever been. Shear is forecast to relax a little today tho isn't it?

Shear is expected to ease some, yes
Member Since: August 17, 2010 Posts: 21 Comments: 6939
1300. GeoffreyWPB
1:23 PM GMT on October 20, 2010
Quoting IKE:


Easy to see now with visible on it. It's exposed.


No argument here.
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1299. scott39
1:22 PM GMT on October 20, 2010
Quoting IKE:


Easy to see now with visible on it. It's exposed.
Will that change?
Member Since: June 13, 2009 Posts: 0 Comments: 6912
1298. cat5hurricane
1:22 PM GMT on October 20, 2010
Quoting IKE:


Easy to see now with visible on it. It's exposed.

...and pretty badly. Conditions aloft handled it alright.
Member Since: August 17, 2010 Posts: 21 Comments: 6939
1297. Neapolitan
1:22 PM GMT on October 20, 2010
Quoting scottsvb:



Wrong... 99L is a very badly exposed LLC to the SW of the convection

99L does currently have an exposed LLC...but the OP stated that it looks better than Nicole did as a depression, and no one can honestly deny that.
Member Since: November 8, 2009 Posts: 4 Comments: 13731
1296. 7544
1:21 PM GMT on October 20, 2010
when then does this nnw turn come in ?
Member Since: May 6, 2007 Posts: 0 Comments: 6874
1295. IKE
1:20 PM GMT on October 20, 2010
Quoting GeoffreyWPB:
20/1145 UTC 17.8N 82.4W T1.5/1.5 99L -- Atlantic


Easy to see now with visible on it. It's exposed.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
1294. pottery
1:19 PM GMT on October 20, 2010
Quoting CaicosRetiredSailor:

typhoonfury:
Raw footage I shot in HD of typhoon #Juan #Megi slamming Philippines as well as aftermath shots - http://youtu.be/R9tckfJrTnI
about 2 hours ago from TweetDeck


typhoonfury:
Back home safely in Hong Kong. In need of a massive meal & lot of rest. Chill out day tmrw before probably venturing into China for #Megi
about 3 hours ago from TweetDeck

Thanks for that, CRS.
Member Since: October 24, 2005 Posts: 0 Comments: 24789
1293. PensacolaDoug
1:19 PM GMT on October 20, 2010
Quoting scottsvb:



Wrong... 99L is a very badly exposed LLC to the SW of the convection



Badly sheared system but the circulation at the lower levels is as defined as it's ever been. Shear is forecast to relax a little today tho isn't it?
Member Since: July 25, 2006 Posts: 0 Comments: 646
1291. scott39
1:17 PM GMT on October 20, 2010
Quoting scottsvb:



Wrong... 99L is a very badly exposed LLC to the SW of the convection
What do you think in the short and long term for 99L?
Member Since: June 13, 2009 Posts: 0 Comments: 6912
1290. GeoffreyWPB
1:15 PM GMT on October 20, 2010
20/1145 UTC 17.8N 82.4W T1.5/1.5 99L -- Atlantic
Member Since: September 10, 2007 Posts: 0 Comments: 11513
1289. scottsvb
1:15 PM GMT on October 20, 2010
Quoting ackee:
99L SURE Looks better than nicole did when the NHC had upgraded it



Wrong... 99L is a very badly exposed LLC to the SW of the convection
Member Since: January 22, 2006 Posts: 0 Comments: 1723
1288. CyclonicVoyage
1:15 PM GMT on October 20, 2010
Quoting pioggiasuper:


I look at this and wonder why anyone says its coming to FL. It could back to the pacific for all we know!


My guess is that it's because that is the prevailing track for cyclones in it's current location. Your talking a 5+ day forecast which is HIGHLY speculative, IMO. Anyone who definitively says it's going here is out to lunch, IMO.

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1287. cat5hurricane
1:15 PM GMT on October 20, 2010
250mb plot 06Z GFS up to 36 hours
Member Since: August 17, 2010 Posts: 21 Comments: 6939
1286. scott39
1:14 PM GMT on October 20, 2010
DOOM!!!!
Member Since: June 13, 2009 Posts: 0 Comments: 6912
1285. CaicosRetiredSailor
1:13 PM GMT on October 20, 2010
Member Since: July 12, 2007 Posts: 0 Comments: 6069
1284. sammywammybamy
1:10 PM GMT on October 20, 2010
Quoting stormwatcherCI:
???????Where u get west from ?


His Pants
Member Since: June 17, 2006 Posts: 44 Comments: 5010
1283. 7544
1:10 PM GMT on October 20, 2010
Quoting Orcasystems:


Actually... 1 has a Cat 5, four more of them have a Cat 4


gfdl 139k

Link
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1282. scott39
1:10 PM GMT on October 20, 2010
Quoting Orcasystems:


Actually... 1 has a Cat 5, four more of them have a Cat 4
:O :O :O :O !!!!
Member Since: June 13, 2009 Posts: 0 Comments: 6912
1281. whadat
1:09 PM GMT on October 20, 2010
Member Since: September 8, 2010 Posts: 0 Comments: 33
1280. Orcasystems
1:09 PM GMT on October 20, 2010
Quoting Vincent4989:

Wow. One of the predicted models is a WTF bomb.


Actually... 1 has a Cat 5, four more of them have a Cat 4
Member Since: October 1, 2007 Posts: 81 Comments: 26512
1279. cat5hurricane
1:08 PM GMT on October 20, 2010
Quoting scott39:
what about some lightning?

Ahhh what the heck. We'll throw that in too.
Member Since: August 17, 2010 Posts: 21 Comments: 6939
1277. scott39
1:07 PM GMT on October 20, 2010
Quoting cat5hurricane:

For some showers & maybe a clap of thunder.
what about some lightning?
Member Since: June 13, 2009 Posts: 0 Comments: 6912
1276. niederwaldboy
1:05 PM GMT on October 20, 2010
richard richard richard!!!!!!
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1275. kitkat954
1:03 PM GMT on October 20, 2010
Quoting CyclonicVoyage:


Because it's all speculation at this point and it's not even classified as a tropical entity yet.



Thanks - I guess they pick and choose which models to show us because these are not the ones I saw this morning.
Member Since: August 8, 2007 Posts: 0 Comments: 11

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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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