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

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

Share this Blog
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

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 425 - 375

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27Blog Index

Pressure is dropping quite rapidly throughout this mission.

20:14:00Z 17.367N 83.517W 976.1 mb
(~ 28.82 inHg) 291 meters
(~ 955 feet) 1009.0 mb
(~ 29.80 inHg)
Member Since: January 30, 2010 Posts: 0 Comments: 3259
Quoting poknsnok:
99l fighting dry air and shear. not looking good down to 30% tomorrow am


I see the kids are home from school
Member Since: June 2, 2010 Posts: 0 Comments: 1339
A bit old...

19/1745 UTC 16.7N 82.9W TOO WEAK 99L
Member Since: Posts: Comments:
Quoting Stormchaser2007:


Doesn't really look "deep" or organized...yet

I'd say that by tomorrow morning this thing has it's act together and becomes a TD or storm.




Sorry, and forgot, that's -70C and cooling tops there on your image, albeit not very large area-wise at this point.

Few more frames.
Member Since: Posts: Comments:
Probably not at 5pm.

ATCF

FNMOC NAVY
Member Since: Posts: Comments:
Quoting Stormchaser2007:


Doesn't really look "deep" or organized...yet

I'd say that by tomorrow morning this thing has it's act together and becomes a TD or storm.




I hear you. But, watch, usually those expand and deepen when directly over the center.

We shall see. Only popped in the past hour.
Member Since: Posts: Comments:
was in westpalm beach florida thru wilma and the back end was worse then the front lost two big avocado trees my screened in back patio and my roof in the family room need i say more.....what are they saying about this 99l possibly hitting southwest florida would it come thru to the east coast or no...
Member Since: Posts: Comments:
Quoting Seastep:


Burst of convection directly over the last vortex fix as of 1945Z.





Now we see if it holds.


Doesn't really look "deep" or organized...yet

I'd say that by tomorrow morning this thing has it's act together and becomes a TD or storm.


Member Since: Posts: Comments:
Definitely passed the TD status when the NHC makes the call.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
99l fighting dry air and shear. not looking good down to 30% tomorrow am
Member Since: Posts: Comments:
99l really looked like it wanted to develop, just to much dry air infiltration and hostile upper level winds.The vaunted season my be coming to a end, to many fronts coming so far south for this time of year.
Member Since: Posts: Comments:
20:04:00Z 17.800N 83.283W

39 knots
(~ 44.8 mph)
Member Since: January 30, 2010 Posts: 0 Comments: 3259
Could be a similar situation to Paloma and Paula.

Quick intensification, then absolutely sheared to nothing in a matter of a day.

Member Since: Posts: Comments:
navy has it 99l
Member Since: Posts: Comments:
Member Since: Posts: Comments:
Quoting Stormchaser2007:
Really doubt that they call this a TD. Circulation structure is okay, but there is virtually no deep convection to speak of. Maybe a special TWO, but I wouldn't really expect more.

But hey...that's just me.





Burst of convection directly over the last vortex fix as of 1945Z.





Now we see if it holds.
Member Since: Posts: Comments:
Quoting Goldenblack:
I was actually talking about the Cayman Islands, but that is a very interesting tidbit about northern Honduras being Dole country, makes sense that area would be good for agriculture with river runoff from mountains and coastal plain.



actually..this place where i live...is the original banana republic...back when chiquita was united fruit and dole was standard fruit...the govt was run by the fruit companies...it was pretty grim..now all that is fixed...as it were...still poor though...but very beautiful here...
Member Since: Posts: Comments:
Really doubt that they call this a TD. Circulation structure is okay, but there is virtually no deep convection to speak of. Maybe a special TWO, but I wouldn't really expect more.

But hey...that's just me.



Member Since: Posts: Comments:
Good afternoon!

5 years ago today:

Hurricane Wilma did the unthinkable and became the strongest Atlantic hurricane on record.
Member Since: Posts: Comments:
IMO, that whole "Best Windshift" remark leads me to believe that if there's indeed closed circulation, then it's ill defined and difficult to pinpoint. (99L)

If they determine that we do have closed circulation, we just bypassed TD and have Richard...
Member Since: Posts: Comments:
Meanwhile, Megi is getting its groove back on; deep convection has wrapped completely around its shrinking eye, and things are beginning to look much more symmetrical. Some portions of the island have been dealing with tropical storm-force winds for nearly 50 hours now:

Click for larger image:

Appropriate tropical weather-related image
Member Since: Posts: Comments:
Quoting Neapolitan:

Sorry the weather can't provide you the stimulation you crave. I suggest you write to Mother Nature immediately and demand a full refund!!!

;-)


LMAO +10
Member Since: Posts: Comments:
They may hold off, though, as it will only have been a couple/few hours of convection over the center.
Member Since: Posts: Comments:
Just not seeing a great deal of them so far, changing its colors pretty steadily now, so bark on..

Quoting CyclonicVoyage:



Several mid-high 40's on the last ob, more like a BARK, BARK.
Member Since: Posts: Comments:
If that CDO persists, TD at least at 5pm.

Last vortex was 17.4N/83.5W. Right under that burst.

Member Since: Posts: Comments:
Quoting Goldenblack:
is more like a "cheep cheep" at this point...lol




Several mid-high 40's on the last ob, more like a BARK, BARK.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
is more like a "cheep cheep" at this point...lol

Quoting CyclonicVoyage:
Walks and talks like a duck.

It's just not looking like a duck yet.
Member Since: Posts: Comments:
19:46:00Z 17.950N 82.883W

45 knots
(~ 51.7 mph)
Member Since: January 30, 2010 Posts: 0 Comments: 3259
Quoting jiminceiba:


problem solved...i just did a system restart...problem went away.....thanks for the advice though....
Great! That was going to be my first suggestion. Most modern operating systems do file housekeeping so to speak on start.



Fewer models runs tracking around in circles:



BAMD headed right for the Basque region.
Member Since: Posts: Comments:
Walks and talks like a duck.

It's just not looking like a duck yet.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
Back later
Member Since: August 19, 2006 Posts: 0 Comments: 15725
I was actually talking about the Cayman Islands, but that is a very interesting tidbit about northern Honduras being Dole country, makes sense that area would be good for agriculture with river runoff from mountains and coastal plain.

And very susceptible to the amount of rain you have been getting, stay safe.

Quoting jiminceiba:

actually...here in honduras..on the north coast..heavy rains can raise havoc with agriculture...there are mountains just a couple of miles south of the ocean, all along the coast..and the coast is where the bananas and pineapples are grown...this is dole country..so, when we get heavy rain...the rivers go crazy and everything floods..including the producing areas..tourist isn't real big here...tropical fruit is
Member Since: Posts: Comments:
Quoting Goldenblack:
Bingo, doesn't it have to be sustained for 6 hours to attain TD by definition?



Something like that. Persistent, deep convection over the coc, I believe.
Member Since: Posts: Comments:
Quoting BLee2333:
41.0 knots (~ 47.1 mph)
Tropical Storm

Wonder if they'll find enough to classify...


Location of that wind

19:37:00Z 17.450N 82.867W

There are quite a few uncontaminated TS readings in this observation.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
Recon found a whole page of 38-41 mph winds.

SFMR found 47 sustained, likely a gust.
41 knots
(~ 47.1 mph)
Member Since: Posts: Comments:
Quoting Goldenblack:
Forgive my ignorance, but I am assuming that tourism is probably the number 1 industry down there. All this tropical activity in the past two weeks must be hurting. Correct me if I am wrong.



actually...here in honduras..on the north coast..heavy rains can raise havoc with agriculture...there are mountains just a couple of miles south of the ocean, all along the coast..and the coast is where the bananas and pineapples are grown...this is dole country..so, when we get heavy rain...the rivers go crazy and everything floods..including the producing areas..tourist isn't real big here...tropical fruit is
Member Since: Posts: Comments:
Yes and so is the dramatically different (not necessarily dramatically improved) satellite presentation. Can really see the definition of circulation now.

Quoting pioggiasuper:
From an Orange Circle to TD 15...very interesting :)
Member Since: Posts: Comments:
41.0 knots (~ 47.1 mph)
Tropical Storm

Wonder if they'll find enough to classify...
Member Since: Posts: Comments:
Quoting Goldenblack:
Right! People always talk about financial services in the Caymans.....that is what I get for not taking the time to look it up (smacks head LOL).



Forgiven LOL !
Member Since: August 19, 2006 Posts: 0 Comments: 15725
Quoting BLee2333:
would you consider it a TD with this?

"BEST WINDSHIFT CENTER WAS AT 19:05:50Z AT 17 31N 83 35W"



With a vortex message and winds supportive of a TD, I would think so.

However,

There could be other factors negating an upgrade, like, the 50% medium chance at 2pm from the NHC.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
Right! People always talk about financial services in the Caymans.....that is what I get for not taking the time to look it up (smacks head LOL).

Quoting kmanislander:


Tourism and financial services are the twin pillars of our economy. Cruise tourism is the strongest portion of the tourism product right now and when we have bad weather the ships might either by pass us entirely or the number of passengers coming ashore are very limited.
Member Since: Posts: Comments:
Quoting BLee2333:
would you consider it a TD with this?

"BEST WINDSHIFT CENTER WAS AT 19:05:50Z AT 17 31N 83 35W"



It means that the winds shifted, as you would expect in a closed circulation.
Member Since: Posts: Comments:

Viewing: 425 - 375

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

Local Weather

Overcast
62 °F
Overcast