Dr. Jeff Masters' WunderBlog

99L a threat to develop; damage from Typhoon Megi still largely unknown
Posted by: Dr. Jeff Masters, 1:38 PM GMT on October 19, 2010 +3
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
Categories: Hurricane
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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: 11143
1303. 7544 1:24 PM GMT on October 20, 2010    
they will relocate the center latter on today maybe further east imo watch
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1304. IKE 1:25 PM GMT on October 20, 2010    
Water vapor....

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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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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
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: 20704
1309. Orcasystems 1:27 PM GMT on October 20, 2010    



Member Since: October 1, 2007 Posts: 77 Comments: 26077
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: 6207
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: 258
1312. clwstmchasr 1:28 PM GMT on October 20, 2010    
Quoting scott39:
Didnt the NHC say earlier that wind shear for 99l will become favorable soon?


Yes. tomorrow
Member Since: July 29, 2006 Posts: 0 Comments: 2753
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: 1065
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: 77 Comments: 26077
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: 37044
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
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
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1319. Neapolitan 1:34 PM GMT on October 20, 2010    
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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: 6207
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: 28
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?
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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
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: 30

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About JeffMasters
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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