Western Caribbean disturbance 99L near tropical depression strength

By: Dr. Jeff Masters , 1:33 PM GMT on October 20, 2010

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A tropical disturbance (Invest 99L) near the Cayman Islands is drifting eastwards towards Jamaica, and has changed little in organization this morning, but is very close to tropical depression status. The storm is bringing heavy rain to the Cayman Islands; 3.85" inches has fallen over the past 48 hours at Savannah on Grand Cayman Island. Heavy rains will continue over the Cayman Islands today and spread to western Jamaica this afternoon. Recent satellite imagery shows that 99L has a well-defined surface circulation, but the center is exposed to view and 99L has a relatively meager amount of heavy thunderstorm activity. Wind shear is marginal for development, 15 - 20 knots, due to the clockwise flow of air around an upper-level high pressure system near the coast of Honduras. The high is bringing strong upper-level winds out of the southwest to 99L. Water vapor satellite loops show considerable dry air to the west and north of 99L, and the strong southwesterly winds over the storm are bringing some of this dry into into the core of the storm, keeping all the heavy thunderstorm development confined to the east side of the center. The waters beneath 99L are very warm, 29°C, but 99L will not be able to take advantage of these warm waters until the shear relaxes. The Hurricane Hunters will be in 99L around 11am EDT this morning to see if the storm is indeed a tropical depression.

Forecast for 99L
The latest SHIPS model forecast predicts that wind shear over the Western Caribbean will stay marginal for development, 15 - 25 knots, for the remainder of today, then decline to the moderate range, 10 - 20 knots, on Tuesday, as 99L positions itself more underneath the upper-level high near the coast of Honduras. Any motion by 99L to the southwest will tend to decrease the shear over 99L, and any motion to the north or east will increase the shear, so 99L's current eastwards drift is detrimental for development. Steering currents will be weak Wednesday through Friday in the Western Caribbean, making it difficult to predict where 99L may wander to, and how much shear might affect the storm. By Saturday, a ridge of high pressure is expected to build in to the north of 99L, forcing the storm on a generally westward track. This should allow 99L to find an environment with less shear. The GFDL and HWRF model predicts a more west-northwestward track, with 99L passing through the Yucatan Channel between Cuba and Mexico on Sunday or Monday as a hurricane. The GFS, ECMWF, and NOGAPS models predict a more west-southwesterly path, with 99L making landfall in Belize Sunday or Monday. NHC is giving 99L a 70% chance of developing into a tropical depression by Friday; I'd put these odds at 80%, and expect this will become Tropical Storm Richard by Thursday.


Figure 1. Morning satellite image of Invest 99L.

Death toll from Super Typhoon Megi in the Philippines remarkably low
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 full extent of the destruction wrought by the great storm is still unclear. However, the death toll from the great storm stands at only 19, reflecting the superior effort Philippines officials made to evacuate low-lying areas and get people out of locations prone to flash flooding and mudslides. Previous major typhoons to strike the Philippines have nearly always killed hundreds, and sometime thousands, so the preparation and evacuation efforts for Megi likely saved hundreds of lives. 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. Severe damage was done to Isabela Province in northern Luzon, and media reports indicate that 200,000 people are homeless.


Figure 2. Visible MODIS satellite image of Megi from NASA's Aqua satellite taken at 1:30am EDT October 20, 2010. At the time, Megi was a Category 4 typhoon with 135 mph winds. Image credit: NASA.

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 intensified into a formidable Category 4 typhoon with 135 mph winds. 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 remain a very dangerous major typhoon through Friday. 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 north of 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. The outer rain bands of Megi are already affecting the coast of China north of Hong Kong, as seen on Hong Kong radar and Taiwan radar.


Figure 3. Still frame of damage to NE Luzon Island from a video posted to YouTube by storm chaser James Reynolds of typhoonfury.com.

Next update
I'll have an update later today, with the timing depending upon what the Hurricane Hunters find.

Jeff Masters

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Invest 99L had been heading 3.2degrees east of SouthSouthEast
18Oct 06pmGMT - 14.6n82.3w - 25knots - 1010mb - ATCF*15.7n83.2w*14.5n82.2w
19Oct 12amGMT - 15.3n82.8w - 25knots - 1009mb - ATCF*15.0n82.6w*15.1n82.7w
19Oct 06amGMT - 16.0n83.1w - 25knots - 1009mb - ATCF*15.7n83.0w*1008mb*15.8n82.9w
19Oct 12pmGMT - 16.7n83.3w - 25knots - 1009mb - ATCF*16.5n83.3w*1008mb*16.5n83.0w
19Oct 06pmGMT - 17.4n83.4w - 30knots - 1008mb - ATCF*17.0n83.0w*1009mb
20Oct 12amGMT - 17.7n83.2w - 30knots - 1009mb - ATCF*17.6n83.4w
20Oct 06amGMT - 17.8n82.9w - 30knots - 1008mb - ATCF
20Oct 12pmGMT - 17.7n82.5w - 30knots - 1008mb - ATCF*1007mb
20Oct 06pmGMT - 17.1n82.2w - 30knots - 1008mb - ATCF
* Before NHC reevaluated&revised the ATCF numbers
20knots=~37km/h _ 25knots=46.3km/h _ 30knots=~55.6km/h

Copy&paste 14.6n82.3w, 15.3n82.8w, 16.0n83.1w, 16.7n83.3w, 17.4n83.4w-17.7n83.2w, 17.7n83.2w-17.8n82.9w, 17.8n82.9w-17.7n82.5w, 17.7n82.5w-17.1n82.2w, ctm, cyo into the GreatCircleMapper for a look at the last 24^hours

Member Since: Posts: Comments:
I don't mean to complain, but this is the forum I always liked to come to to get the most insightful and accurate tropical forecasts. Sadly, I've noticed over time it has turned into a hodge-podge of mostly silly talk that has nothing to do with weather.

I still recognize some of the names that I had come to respect, but, some others are no longer to be found. Many new names have popped up. That would be fine if they would stick to the subject matter. I know I have no authority on here...but can you all PLEASE get back to what this forum is to be about. Leave the juvenile jokes, sports center talk, recipe ideas, etc., etc. out of this forum.

Dr. Masters, I hope you agree...
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NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
240 PM EDT WED OCT 20 2010

MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA
AND TROPICAL N ATLC...

WINDS REMAIN GENERALLY 10-15 KT ACROSS THE CARIBBEAN. A 1007 MB
LOW NEAR 18N83W HAS LOST ALL NEARBY CONVECTION TODAY...AND IS
EXPECTED TO DRIFT S THROUGH FRI THEN MOVE W TOWARD THE CENTRAL
AMERICAN COASTS OF HONDURAS AND NICARAGUA SAT AND SUN. VERTICAL
SHEAR IS FORECAST TO DIMINISH BY FRI...AND THE LOW MAY DEVELOP
INTO A TROPICAL CYCLONE BEFORE REACHING CENTRAL AMERICA.



http://www.nhc.noaa.gov/text/MIAMIMATS.shtml


Member Since: July 12, 2007 Posts: 0 Comments: 6051
Quoting bwi:
Kind of interesting that the HH went down to 120 meters flight level on their last pass. I guess when you're flying in the clear...


They were checking the SSTs...
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Quoting Jeff9641:
Off topic but when the hell is Wade Phillips going to get fired. Dallas 1 & 4 just doesn't sound right with all that talent.
Wade probably won't get fired because of the possible lockout next season...too much hassle...:(
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Quoting SeniorPoppy:


LOL...If I hear Wilma one more time on here..

The shear would tear this disturbance apart.
You mean if you "read" Wilma! LOL.
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Quoting victoriahurricane:


Minimal damage? Have you seen this video?

http://www.abs-cbnnews.com/video/nation/10/20/10/juan-ravages-palanan-isabela

Phillippines damage must be in the 100's of millions if not billions of dollars crops have failed everywhere. Lives lost is small I agree, but saying Megi did minimal damage is ridiculous.
their goverment reported only $30M for both, but will probably go up. Comparing it to what they usually get, yes I would say it is minimal, since it didn't hit in vastly populated area.
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Quoting acyddrop:


Oh I agree completely on the unreliable nature of the GFDL early on but it does get a good handle on it later as the storm presents itself. The thing I still really disagree with in it's forecast at 12Z is maintaining any kind of momentum in the gulf that just doesn't seem very likely. My biggest take away from any of these models even the ones not predicting too much right now is to keeping an eye on 99L is absolutely prudent.


I agree with all your points.

And yes, it sure is hard to believe that a storm entering the Gulf in this year, with all the shear and the lower-than-average SSTs is going to be at Cat 3 or Cat 4 strength all the way up to a FL landfall.

You never know exactly what the models are working with in the early runs. For example, they might not be factoring in climatology enough or they may be picking up on some obscure detail in the atmosphere and that detail may be causing a misinterpretation of some other factor, which in turn is causing something else, maybe a data dropout or something.

Once the storm gets named though, it is a whole different story. So much more data gets entered into the program and now the model has something really solid to work with.
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Quoting lightningbolt73:
Good afternoon all! I've got a question! I just posted a comment quoting a member and I don't see my comment. Would someone mind showing me how to set it up so I can see my comment when I quote a member? thanks.

No set-up needed.
Click on 'quote' and scroll down to the comments box, add comment and click 'post comment'.
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Quoting lightningbolt73:
Good afternoon all! I've got a question! I just posted a comment quoting a member and I don't see my comment. Would someone mind showing me how to set it up so I can see my comment when I quote a member? thanks.


Posts do get eaten on occasion, but always refresh once or twice before reposting because there can also be a delay in it showing up. Happens all the time on the initial "Post Comment."
Member Since: September 9, 2008 Posts: 6 Comments: 3414
Good afternoon all! I've got a question! I just posted a comment quoting a member and I don't see my comment. Would someone mind showing me how to set it up so I can see my comment when I quote a member? thanks.
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Quoting Floodman:


No, they wet them down...keeps him disoriented enough that they can give him his meds...LOL

Ah! Thanks for clearing that up.
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Quoting pottery:

Hello, young Fellow.
they changing your sheets?


No, they wet them down...keeps him disoriented enough that they can give him his meds...LOL
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Quoting Grothar:


Didn't know you worked for the Susquehanna Hat factory, or was that Niagara Falls? LOLOLOLOL


Now THAT'S some funny stuff...LOL

I myself prefer the "Susquehanna Hat Company"...
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Quoting Jeff9641:
News 13 in Orlando is saying that the NHC as feeling that a FL landfall from this thing next Tuesday is a good bet. Sorry downcasters!


I wouldn't have made that call yet. Not without a caveat or two.
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Quoting Levi32:
Vertically growing cumulus bands west and south of the center indicate that 99L is ready to develop a core if the wind shear and dry air will allow it. We could see this get named in a hurry if we get a convective burst near the center to tighten in a well-defined vortex.



Levi, I'm a rookie but does that sat photo also look like some banding?
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Quoting katadman:



Hey, wildman. Good to see you. Just enjoying the banter between the doomsayers and naysayers.


It's pretty funny stuff, isn't it?
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Quoting pottery:

Yeah! And when I click on it, all I get is a small blue ?.
A shame, really....


LOL. Was thinking the same thing!
Member Since: September 9, 2008 Posts: 6 Comments: 3414
Quoting Grothar:


Didn't know you worked for the Susquehanna Hat factory, or was that Niagara Falls? LOLOLOLOL

Hello, young Fellow.
they changing your sheets?
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Quoting FLWaterFront:


The thing to watch will be how the GFDL and HWRF handle this system once it becomes a TD or especially once it has actually made hurricane status in a couple of days.

In the past, these models and others, such as the Euro and the CMC have had a tendency in some years to way overdo a storm forecast when the system is still an invest. But once the system develops a closed circulation, gets vertically stacked and finally gets going for real then the models have much more reliable data to work with and become more realistic.


Oh I agree completely on the unreliable nature of the GFDL early on but it does get a good handle on it later as the storm presents itself. The thing I still really disagree with in it's forecast at 12Z is maintaining any kind of momentum in the gulf that just doesn't seem very likely. My biggest take away from any of these models even the ones not predicting too much right now is to keeping an eye on 99L is absolutely prudent.
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Ciao, y'all.
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381. HCW
99L 18Z model runs from the NHC with Intensity

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Quoting Jeff9641:


Hey bud nice avatar!

Yeah! And when I click on it, all I get is a small blue ?.
A shame, really....
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Quoting Floodman:


Slooowly I turned...step by step...


Didn't know you worked for the Susquehanna Hat factory, or was that Niagara Falls? LOLOLOLOL
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378. Jax82
FYI

Member Since: Posts: Comments:
Quoting Jeff9641:
Off topic but when the hell is Wade Phillips going to get fired. Dallas 1 & 4 just doesn't sound right with all that talent.


After the end of the season, unless the team makes a dramatic turnaround in the meantime.

However, the GFDL is showing him as canned by 5PM CDT today!

j/k ;-)
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Quoting Jeff9641:


Hey Pottery, what's cooking friend.

Doing Good, as the showers come down.
Some flooding in the City on Monday, with one bank having their entire basement area filled to ground level with muddy water from an overflowing paved river!
Pandemonium with people trying to get out of the City and all but one exits closed!

Just coming out of our "Petit Careme" which is a 2 week dry spell around this time of year.
Some strong gusts recently, blowing off the occasional roof.
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Quoting Jeff9641:


That's the one the NHC uses. Any intensity forecast for that model.


Not sure where to get that. SFWMD just posts the plots.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
That being said, a few more runs will be the tell tale.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
It seems like the forecasted track of megi has sure changed since yesterday! There's now another system developing in the west pac!
Quoting victoriahurricane:


Minimal damage? Have you seen this video?

http://www.abs-cbnnews.com/video/nation/10/20/10/juan-ravages-palanan-isabela

Phillippines damage must be in the 100's of millions if not billions of dollars crops have failed everywhere. Lives lost is small I agree, but saying Megi did minimal damage is ridiculous.
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That's a pretty significant development as the TCVN has held a southern solution from the get go.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
Quoting acyddrop:


It isn't even heading at Florida anymore until the end of the run and is actually better aligned with the environmental conditions that are in play right now. Intensity is probably still too high but it's being more realistic at 12Z.

Link


The thing to watch will be how the GFDL and HWRF handle this system once it becomes a TD or especially once it has actually made hurricane status in a couple of days.

In the past, these models and others, such as the Euro and the CMC have had a tendency in some years to way overdo a storm forecast when the system is still an invest. But once the system develops a closed circulation, gets vertically stacked and finally gets going for real then the models have much more reliable data to work with and become more realistic.
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366. afj3
Can we expect doom and damnation for South Florida from 99l or just garden-variety doom?
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Quoting chrisdscane:


is ur tidbit out yet?


Yes.
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Quoting bwi:
Kind of interesting that the HH went down to 120 meters flight level on their last pass. I guess when you're flying in the clear...

Good thing that Kman was'nt out there on his boat.
They might have clipped his mast....
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TCVN now switched around more in line with the HWRF and GFDL 12Z

Member Since: January 30, 2010 Posts: 0 Comments: 3259
TAFB is going with the southern solution as of 12Z.

Member Since: September 9, 2008 Posts: 6 Comments: 3414
99L looks like its trying to build some convection on the S and NW sides.
Member Since: June 13, 2009 Posts: 0 Comments: 6871
358. bwi
Kind of interesting that the HH went down to 120 meters flight level on their last pass. I guess when you're flying in the clear...
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Quoting BobinTampa:


excellent good sir! back to teh tropics. is this a South Florida threater? thank you in advance most kind sir.

:o)

Only if you wish it so, Bud!
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Quoting pottery:

and the initials stand for Just Freaking Vexing.
Now, enough of that!


excellent good sir! back to teh tropics. is this a South Florida threater? thank you in advance most kind sir.

:o)
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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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