Little change to 99L, which remains very close to tropical depression status

By: Dr. Jeff Masters , 7:11 PM GMT on October 20, 2010

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A tropical disturbance (Invest 99L) centered 160 miles southwest of the Cayman Islands is moving south to southeast at 5 - 10 mph. A Hurricane Hunter flight arrived in the storm at about 11am this morning, and found a closed circulation with top winds at flight level (700 feet) of 33 mph. A closed circulation and 30 mph surface winds are necessary conditions for a tropical depression to exist, but the storm must also have a great deal of heavy thunderstorm activity near the center that persists for many hours. In the judgment of NHC, 99L does not qualify as a tropical depression in that regard. The storm is bringing heavy rain to the Cayman Islands; 4.14" inches has fallen over the past 2 1/2 days at Savannah on Grand Cayman Island. Heavy rains have diminished over the Cayman Islands, but have spread to western Jamaica and west-central Cuba this afternoon. Recent satellite imagery shows that the surface circulation center is exposed to view, and 99L has a relatively meager amount of heavy thunderstorm activity. The center is more than 80 miles west of the heaviest thunderstorm activity, and it is likely that 99L's center will relocate itself to the east to be more underneath the heaviest thunderstorms. 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. A new hurricane hunter aircraft will be in the storm tonight near 8pm EDT.

Forecast for 99L
The current southward movement of 99L is carrying the storm into a region of lower wind shear, and we should see 99L accumulate more heavy thunderstorm activity near its center beginning tonight. The latest SHIPS model forecast predicts that wind shear over the Western Caribbean will decline below 15 knots Thursday afternoon through Saturday afternoon, which should allow the storm to become a tropical depression by Thursday. Steering currents will be weak today through Friday in the Western Caribbean, making it difficult to predict where 99L may go. The models are split into two camps, with the GFDL and HWRF models taking 99L to the west-northwest over the western tip of Cuba or the Yucatan Peninsula on Sunday as a hurricane. The rest of the models take 99L to the south over Honduras on Sunday, and keep the storm below hurricane strength. Given 99L's current southward motion and the possibility that the center will relocate farther to the east later today, this makes a track to the southwest towards Honduras more likely, I predict. NHC is giving 99L a 70% chance of developing into a tropical depression by Friday, which is a reasonable forecast. I expect this will become Tropical Storm Richard by Friday.


Figure 1. Afternoon 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 3 typhoon with 125 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, or as a strong Category 2, 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 Thursday morning.

Jeff Masters

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Quoting reedzone:
The GFDL makes alot more sense on this run, course it is the 12Z run, a better, amplified run. A major slamming into Mexico, then catches a trough in the GOM, moves NE. Very umm, Wilma like. It's a possible scenario. Not buying the HWRF yet, too far north. I believe that conditions will get favorable as predicted and this may surprise lots of umm downcasters in here ;)

*This is my personal opinion, don't hate*

Reed: Don't woory about the dowmcasting Reed haters. You are my Favorite Wishcaster. That is a complament.

Do you think it will go into FL?
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Quoting Stormchaser2007:
12z HWRF

(Not for the faint of heart)

Please dont show me that scary monster again! I just know it will come true!!LOL
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Quoting belizewunderfan:

:( Can you or someone please pinpoint the center of 99L? it is not so easily defined to the untrained eye....thanks!


POSS T.C.F.A.
XX/XX/99L
MARK
17.73N/81.88W
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Quoting CyclonicVoyage:


5 day cone would still be in the NW Caribbean.


Given the model spread, the 5 day cone will likely be a giant circle with the middle being the current COC and extending from Panama to the Bahamas...might as well include Florida and New Orleans in there.
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Quoting Stormchaser2007:
12z HWRF

(Not for the faint of heart)



Nice job setting in panic into the site :P haha jk. The HWRF isn't very realistic in its intensity forecast over the next 24-48 hours.
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Quoting Jeff9641:
This blog seems to be spiraling out of control now with imposters.

Probably just 1 or 2 Trolls causing trouble. Ignore!
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Quoting Waltanater:
SouthDade...do you also reside in South Dade, FL? Just curious.
Yes I do. I'm currently an undergraduate student at Florida International University, studying meteorology.
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Quoting 7544:
if this does become a td will fla be in the cone if the nhc follows the tvcn model or others they seem to br trending that direction tia


5 day cone would still be in the NW Caribbean.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
65. 7544
if this does become a td will fla be in the cone if the nhc follows the tvcn model or others they seem to br trending that direction tia
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Holy Crap!
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Quoting Jeff9641:


Oh I see what your saying. I'm sorry I didn't understand what you meant but yes you are right.
No worries, sorry if I came across as rude or anything. You are correct with the statement that the NHC tends to follow this consensus frequently, however sometimes they will deviate from the TVCN if they feel it is biased and doesn't match synoptics. I believe if they issued a track right now, it would be very similar to the 12Z Euro.
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12z HWRF

(Not for the faint of heart)

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Quoting BobinTampa:


I'm not sure that's irony. :o) Irony is dedicating your life to saving the whales and then getting eaten by a whale. Irony is writing an entire song about irony in which none of the examples are actually ironic.


LOL

OK...I respectfully withdraw the word "Ironically". Better? ;-)
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It is starting to moisten up all the way around 99L.
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This is for Jeff.

12z HWRF.

900mb winds of 136 knots



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Quoting Stormchaser2007:


At the center of this image. (Not in the convection)


Thanks a lot!
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Quoting Stormchaser2007:


At the center of this image. (Not in the convection)


About 17N, 82W
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Quoting SouthDadeFish:
I agree. Once again, what is concerning about this storm is its potential, as the GFDL and HWRF demonstrate.
SouthDade...do you also reside in South Dade, FL? Just curious.
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Quoting DookiePBC:


Ironically, given the dry conditions so many places are experiencing right now, I think think people are hoping this comes their way. Granted...without the hurricane winds if possible.


I'm not sure that's irony. :o) Irony is dedicating your life to saving the whales and then getting eaten by a whale. Irony is writing an entire song about irony in which none of the examples are actually ironic.
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Quoting SouthDadeFish:
Thanks for the shout out on the site :~) Glad you enjoy it and recommend it to other people! I'll keep updating it as I find more great links.


No problem.

Use your site almost every day and I've also sent it to quite a few people over the past few months.

Thanks for putting it together!
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Yes, Kudos to the guy who made it, definitely! Excellent. Thanks for referring it as well. I have book marked it.
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WILMA WILMA WILMA PART 2 GONNA HAPPEN
OCTOBER 25-31.
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Quoting reedzone:


That's ok Pottery. I'm not looking for much of an impact in Florida if this does head this way, the subtropical jet should weaken it alot.


Ironically, given the dry conditions so many places are experiencing right now, I think think people are hoping this comes their way. Granted...without the hurricane winds if possible.
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Quoting belizewunderfan:

:( Can you or someone please pinpoint the center of 99L? it is not so easily defined to the untrained eye....thanks!


At the center of this image. (Not in the convection)

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Quoting Stormchaser2007:
Personally, I think the ECMWF solution wlll come very close to verifying.

Landfall somewhere on the Yucatan, then what ever is left could be drawn NE. Probably nothing more than a remnant low or depression.



I agree. Once again, what is concerning about this storm is its potential, as the GFDL and HWRF demonstrate.
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Quoting Waltanater:
Thanks Chaser! Great link. Very informative indeed!


That's actually SouthDadeFish's site.

He took the time to compile all those link.

Kudos to him.
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Quoting reedzone:


That's ok Pottery. I'm not looking for much of an impact in Florida if this does head this way, the subtropical jet should weaken it alot.


I'll take the rain. it could head this way as a weak tropical storm, dump about 4 or 5 inches of rain and then get pushed out by a cold front. A couple days of rain followed by 75 degree temps...yeah, I'll sign up for that.
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Quoting reedzone:
The EURO has landfall as a strong TS/Hurricane near Belize. Interesting, nothing from the last run to a Strong TS/Hurricane on the next run.

:( Can you or someone please pinpoint the center of 99L? it is not so easily defined to the untrained eye....thanks!
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Personally, I think the ECMWF solution wlll come very close to verifying.

Landfall somewhere on the Yucatan, then what ever is left could be drawn NE. Probably nothing more than a remnant low or depression.



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Quoting Jeff9641:


If NHC issues a track it will most likely be from the TVCN model. It is very important to note the drastic shift north on this run from the 06Z run.

TVCN - Consensus of GFS, UKMET, NOGAPS, GFDL, HWRF, GFDN, and ECMWF models (replaces old CONU model)
I understand what the TVCN is, all I'm saying is that it is not a really a model. It is simply a consensus. It is true that the NHC often uses it for a forecast track. I feel it is a little biased to the north at this time due to the HWRF.
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Thanks Chaser! Great link. Very informative indeed!
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Quoting Stormchaser2007:


Bookmark this page.

Everything you could possibly need and more...
Thanks for the shout out on the site :~) Glad you enjoy it and recommend it to other people! I'll keep updating it as I find more great links.
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Notice the multiple models still to the south. The hook at the end of the run is concerning though. If a track like that does occur, it will be interesting to see what upper-level conditions will prevail.
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Quoting Waltanater:
Can you provide a link to that TVCN please?


Bookmark this page.

Everything you could possibly need and more...
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Quoting pottery:

Hey Reed!
I appreciate your forecasts, man.
My previous remark was only intended to diss. the recent imposter on the blog.
Was not directed at you.


That's ok Pottery. I'm not looking for much of an impact in Florida if this does head this way, the subtropical jet should weaken it alot.
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CU blossoming near the center
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Typhoon Megi Leaves Northern Philippine Towns in Ruins

Rural towns in the northern Philippines are on alert after warnings that heavy rains from Typhoon Megi could continue through the night.

Megi left rural towns in the farming province of Isabela in ruins as it barrelled past with strong winds, blowing away rooftops and destroying homes made of light materials.

Downed trees, house appliances, and roof sheets littered the streets, as residents were busy reconstructing their homes. Walls were splattered with mud and windows lay cracked.

Power has not been restored.

On Tuesday soldiers joined residents in clearing fallen trees and patching up houses that had lost their roofing and walls.

Officials said some towns facing east to the Pacific Ocean remained unreachable.

Most houses appeared to have been destroyed after Megi hit land as a category 5 super typhoon with winds in excess of 150 m/h on Monday.
Link

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Quoting Jeff9641:
The Euro, TVCN, GFDL, and HWRF basically have the same thinking now with 99L. GFS behind the ball as usual. Hey should we get a downcast comment now or are all four of these models now wrong.
The TVCN is not a model and is so far east due to the outlier HWRF at this time. That makes only three models with a far northern component. Not saying this scenario wont happen, but there still are many models that keep this farther south. I believe we will see a motion towards the Yucatan, but I am skeptical because of the quick strengthening the GFDL and HWRF are showing in the next 24 hours. GFDL has a hurricane in 24 hours while the HWRF bombs it to 990 mb in 24 hours. Not very likely to me at this time.
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Can you provide a link to that TVCN please?
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Quoting reedzone:
The GFDL makes alot more sense on this run, course it is the 12Z run, a better, amplified run. A major slamming into Mexico, then catches a trough in the GOM, moves NE. Very umm, Wilma like. It's a possible scenario. Not buying the HWRF yet, too far north. I believe that conditions will get favorable as predicted and this may surprise lots of umm downcasters in here ;)

*This is my personal opinion, don't hate*

Hey Reed!
I appreciate your forecasts, man.
My previous remark was only intended to diss. the recent imposter on the blog.
Was not directed at you.
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Quoting Waltanater:
Can you provide a link for these runs please?


12Z EURO at 120 hours, landfall near Belize, MX
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Japan Meteorological Agency
Tropical Cyclone Advisory #5
TROPICAL DEPRESSION 18
3:00 AM JST October 21 2010
=================================

SUBJECT: Tropical Depression Near The Marianas

At 18:00 PM UTC, Tropical Depression (1004 hPa) located at 16.1N 144.8E has 10 minute sustained winds of 30 knots with gusts of 45 knots. The depression is reported as moving west at 9 knots

Dvorak Intensity: T1.5

Forecast and Intensity
=======================
24 HRS: 16.0N 140.1E - 35 knots (CAT 1/Tropical Storm)
Member Since: May 24, 2006 Posts: 51 Comments: 45739
Gulf is looking very....stable.

Doubt that will change much until next season.

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Quoting reedzone:
The EURO has landfall as a strong TS/Hurricane near Belize. Interesting, nothing from the last run to a Strong TS/Hurricane on the next run.
Can you provide a link for these runs please?
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Quoting Stormchaser2007:
ECMWF dissipates 99L as it makes it's way into the Gulf.

(Using StormVista)


Yep, the remnants surprisingly head to New Orleans LOL.
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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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