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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775. afj3
Quoting afj3:

Will that moving air ahead of that dry air move it east or will that thing over those other states let it move north and to that other place?

Sorry. I am not making any sense at all...
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774. afj3
Quoting shikori:
99l will probably lumber in the Caribbean for a while before it decides to do anything.

Will that moving air ahead of that dry air move it east or will that thing over those other states let it move north and to that other place?
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Hey Kman - gfdl swells 99l up then take it to cuba but appears to roll it around the coast headed ne. What is your opinion on track ifit does swell up as shown?
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hysterical.
roflmao

how close to Hong Kong will Megi make landfall?
it looks more north than forecasted earlier today.
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Quoting Chicklit:
oh oops. thought this would be him. guess not.

Richard is the next TC in the Atlantic :OP
Member Since: August 25, 2009 Posts: 20 Comments: 6785
Quoting Chicklit:
oh oops. thought this would be him. guess not.
You do know the next named TC is Richard?
Member Since: June 13, 2009 Posts: 0 Comments: 6706
Quoting Chicklit:
oh oops. thought this would be him. guess not.


You mean Richard, or Dick to his friends ?
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oh oops. thought this would be him. guess not.
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Quoting Chicklit:
high and dry to the north of 99L



if michael is to be he'd best stay in the caribbean.
Michael??
Member Since: June 13, 2009 Posts: 0 Comments: 6706
Quoting Chicklit:
high and dry to the north of 99L



if michael is to be he'd best stay in the caribbean.


Who is Michael ??
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764. afj3
Evening everyone!
I was away from my computer for a huge swathe of the day and evening and came back to see that little red circle on the NHC site (no longer yellow or orange). What happened? South Florida in the clear?
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Quoting AEKDB1990:
With the setup to the north I think a Paula like storm is the strongest possible outcome. And I doubt this will get that strong.


It looks like the whole BLOB is going to flow NE into East Cuba and into the Bahamas?

Live in North Florida! Could use the rain!
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high and dry to the north of 99L



if michael is to be he'd best stay in the caribbean.
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Quoting scott39:
Why is it taking so long to build convection and keep it?


The same two problems that have plagued every system this year, namely dry air and shear. 99L is surrounded by dry air and has been ingesting some today. In addition, the shear tendency map indicates increasing shear all around the system today. In fact, it sits now in a very small pocket of relatively low shear.

In summary, conditions aloft not entirely ideal for development.There is an anticyclone nearby but not directly overhead the center.

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99l looks great and will be td 19 at the 11.
I can't stay on long so bye

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Quoting kmanislander:
Good evening all

99L looks to me to be near 17.4 N and 82.8 West or essentially stationary with a drift to the East.

A new round of convection starting over the center this evening.

Good Evening, same thing I thought , though I stated a drift ENE a few post back, what I don't like is slow movement, this system IMO has the potential to just sit , intensify and create havoc for us, but thats my take only!
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Quoting kmanislander:


Hi, I didn't read back. Was there some discussion about motion ?
I said a few posts back that it looked a little farther E than than 83.4W
Member Since: June 13, 2009 Posts: 0 Comments: 6706
While Doc Masters' opinion was Yucatan, he qualified that with this comment,

...steering currents will be weak Wednesday through Friday, making it difficult to predict where 99L may wander to.

thus the spider model.
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Quoting Chicklit:

Nice here too but we need rain.

Yes i can agree with that. I have had no rain in october as of today. The grass looking a little blah. At least i dont have to cut it 4 weeks now.
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Quoting kmanislander:
Good evening all

99L looks to me to be near 17.4 N and 82.8 West or essentially stationary with a drift to the East.

A new round of convection starting over the center this evening.
Why is it taking so long to build convection and keep it?
Member Since: June 13, 2009 Posts: 0 Comments: 6706
Quoting Chicklit:
Hi Kman,

Thanks for the confirmation to the east.


Hi, I didn't read back. Was there some discussion about motion ?
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Hi Kman,

Thanks for the confirmation to the east.
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link to GFDL 99L
Link
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Good evening all

99L looks to me to be near 17.4 N and 82.8 West or essentially stationary with a drift to the East.

A new round of convection starting over the center this evening.
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Quoting stormpetrol:

No , not really to be honest, link please

oops just seen it above, to be honest thats kinda in line with what I'm fearing, though I'm personally not a storm "model" fan, though some here would bet the farm on them if you know what I mean!
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megi going closer to Hong Kong than expected, isn't it?
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746. IKE
Shear forecast with SHIPS through 60 hours on 99L...

SHEAR (KT) 16 21 20 21 26 17 15 12
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Quoting severstorm:

Because west central fl is me and i dont want it here. nice outside 68 here

Nice here too but we need rain.
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Quoting weatherlover94:


have you checked out the latest GFDL on 99L

No , not really to be honest, link please
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Quoting RufusBaker:


Why is it always south FL why not west central FL??

Because west central fl is me and i dont want it here. nice outside 68 here
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you are a funny boy weatherlover.



I think they need to move the floater.
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Quoting stormpetrol:
I personally think 99L has the potential to become a very dangerous system, JMO.


have you checked out the latest GFDL on 99L
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Quoting Chicklit:

what megi?


no mam 99L
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Pressure rose 1mb. Winds remain the same as the system moves slowly towards the north.

AL, 99, 2010102000, , BEST, 0, 176N, 834W, 30, 1009, LO

Satellite estimates have increased however. SAB and TAFB both at T1.0. In reality though, this is still quite low for a tropical depression.

19/2345 UTC 17.7N 83.4W T1.0/1.0 99L

TAFB, JA, V, 5, 1010 /////, , , GOES13, CSC, T, DT = 1.0 BASED ON 0.3 BANDING. NLINE NLINECLOUDINE
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dry air and ulls sucking the life out of everything.
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Looks like 99L COC has moved a little to the E. Convection is starting to fire around what seems to be the center.
Member Since: June 13, 2009 Posts: 0 Comments: 6706
ATCF says 99L's pressure has gone up a millibar to 1009, while winds are still at 30 knots. 17.6N/83.4W

AL, 99, 2010102000, , BEST, 0, 176N, 834W, 30, 1009, LO, 34, NEQ, 0, 0, 0, 0, 1011, 200, 50, 0, 0, L, 0, , 0, 0, INVEST, M,
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Quoting MiamiHurricanes09:
99L has continued to get better organized though it still lacks organized and deep convection. Just a minor increase in organization will likely result in the formation of a tropical depression. My best guess as to when this will occur is during the morning hours of Wednesday.

I think you're right on the button, 4am CST, around D/Max
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Very anemic looking on water vapor imagery.

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Quoting Jeff9641:


Oh you will and it could move fas past Cuba toward FL. You will see landfall Tuesday in SW FL.


I've noticed that some people are claiming that Richard will develop into a major hurricane over the Caribbean Sea during the next couple of days. This is a good possibility, IMO.

But some are also making the claim, already, that Richard will then eventually get pulled N/NE into the GOMEX and hit Florida, with the implication being that it will still be a major hurricane when that happens.

Some mention also that Levi32 made reference to the possibility that this storm could eventually get pulled in a northerly direction, over the Gulf and perhaps threaten the SE US and indeed he did. But he also said that it may pay a visit to the Yucatan first before doing this, in his excellent video blog analysis from this AM.

And Levi pointed out that the good news (for the US) is that the subtropical jet seems to be setting up shop over the GOM in the area roughly from 22-25N. He didn't elaborate on this but I assume that he meant that this factor will make it difficult for hurricanes to move freely into the Gulf and make landfall at maximum strength.

So I have a question. So far, I have not seen this addressed here in detail by anyone, most especially those who are claiming that Florida is under the gun for a major hurricane strike next week...

My question is how are the lower SSTs in the Gulf, the obviously lower Tropical Cyclone Heat Potential (TCHP) in the Gulf of Mexico vs. that in the Caribbean and the potentially hostile upper level winds over the Gulf going to affect Richard if he decides to take a big jaunt to the north?

I am not trying to be a downcaster here so much as trying to find out what others with a lot of knowledge about this subject think about these factors. Thanks.
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I personally think 99L has the potential to become a very dangerous system, JMO.
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Quoting weatherlover94:
the latest GFDL has the winds at the end of the period at 130 knots 150 mph....devistating!! if that comes true

what megi?
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the latest GFDL has the winds at the end of the period at 130 knots 150 mph....devistating!! if that comes true
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99L an invest with prospects.
Was it 70% at 8 pm?

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Quoting Chicklit:
Hi Wunderfolks,
Models are all over the place with 99L


So True confused as we are! Looks like its drifting east of due N or even ENE.
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Quoting Stormchaser2007:
Extremely hostile.




looks mabie like the atmosphere is trying to moisten up a little but cant tell yet
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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.