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

By: Dr. Jeff Masters , 19:11 GMT le 20 octobre 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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There is white in that lime, no?

Little help, please. Color-blind.

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Member Since: 9 septembre 2008 Posts: 6 Comments: 3414
Quoting AEKDB1990:
TD 19 is looking better. I'm not confident about the track at all. HWRF is still not good. But we've never had a major hurricane hit FL that late in the historical record.

I hate to break to you buddy by the way I hope everyone his having a good night as my arm just fought a war with my pathfinder, but here is what I'm talking about Link
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Quoting AEKDB1990:
TD 19 is looking better. I'm not confident about the track at all. HWRF is still not good. But we've never had a major hurricane hit FL that late in the historical record.


Wilma (Cat 3) October 24, 2005.
Member Since: 30 janvier 2010 Posts: 0 Comments: 3259
sorry,old news...
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gn Kman.
We'll see what tomorrow brings.
Member Since: 3 août 2005 Posts: 10 Comments: 5684
Hello Megi!

Member Since: 2 août 2006 Posts: 47 Comments: 11709
anyone see we have td19??
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Quoting kmanislander:


I've had this station about 2 years now but changed out the anemometer recently for a heavy duty one with shielding from salt spray for the swivel arm bearing.

Really accurate with lots of features. When you set it up you programme in the lat and lon for your location including elevation above sea level etc. and the system actually knows where it is on the planet. Thus, it can accurately provide phases of the moon, forecasts etc.

Pretty neat.

Sounds cool. Now I know what to put on my santa list! LOL. Until tomorrow.
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Quoting kmanislander:


Yeah, both posts on the same thread at the same time. It has happened before LOL


Same topic, too, though... ;)
Member Since: 9 septembre 2008 Posts: 6 Comments: 3414
no pottery you are wrong I did not say anything about cuba I think the places that will be mostly affected would be the Cayman Islands (Grand Cayman) and the yucatan
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Quoting caymanlurker:

Well it has been a wet few weeks here in Cayman but I will take that if we avoid what you describe! How's the new weather equipment working out?


I've had this station about 2 years now but changed out the anemometer recently for a heavy duty one with shielding from salt spray for the swivel arm bearing.

Really accurate with lots of features. When you set it up you programme in the lat and lon for your location including elevation above sea level etc. and the system actually knows where it is on the planet. Thus, it can accurately provide phases of the moon, forecasts etc.

Pretty neat.
Member Since: Posts: Comments:
Quoting kmanislander:
The intensity forecast is the wild card here. The NW Caribbean is well known for exceeding intensity forecasts time and time again. The SST and TCHP will still support a major and a system with time on its hands basically strolling around this area could become a dangerous proposition.

Let's hope not but not out of the question.

Well it has been a wet few weeks here in Cayman but I will take that if we avoid what you describe! How's the new weather equipment working out?
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nite all.
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Quoting Hurricanes101:


they also said in the 1st advisory of Paula that she would not be a hurricane

I would watch the intensity of this system very closely; a weaker storm is likely to follow the NHC track, but if this intensifies further than predicted, that is where we could see that turn northward sooner and it missing land

The bamd (deep) model has a stronger storm not moving very fast at all and just missing w cuba before heading back towards sw FL.
I believe this could be a possibility if it strengthens quicker than expected.
Just a thought though here, I leave it upto the experts at the nhc as they seem to have done a pretty good job this year and seem to get better from year to year. Now if they could only nail down intensity, lol
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Quoting Seastep:
Spooky. LOL.


Yeah, both posts on the same thread at the same time. It has happened before LOL
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Spooky. LOL.
Member Since: 9 septembre 2008 Posts: 6 Comments: 3414
Well, I am out for tonight, unless nasty weather wakes me up in which event I will have to check in to see what is going on LOL

Have a great evening folks. Back in the morning.
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I have to disagree with the NHC on intensity. Mainly in the short-term, but that affects the long term.

If it sits there and keeps that upper level high atop, I do not see how it does not intensify quite rapidly.

On their track, it stays in the same area for two days. If that feature stays with it, I do not see this being a TS in two days. Highly unlikely, imo. Not having looked at everything, they must really be counting on dry air or that feature moving.

If the upper level feature does move away from the llc or vv, that would also be a problem for the system.

But they seem to have been trying to colocate the whole time.
Member Since: 9 septembre 2008 Posts: 6 Comments: 3414
The intensity forecast is the wild card here. The NW Caribbean is well known for exceeding intensity forecasts time and time again. The SST and TCHP will still support a major and a system with time on its hands basically strolling around this area could become a dangerous proposition.

Let's hope not but not out of the question.
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Quoting kmanislander:


Not suspect anymore though, suspicions confirmed LOL



That's for sure, finally. A lot of speculation on the table the next couple days.
Member Since: 30 janvier 2010 Posts: 0 Comments: 3259
Quoting sunlinepr:
If cyclogenesis is dificult to pronosticate, Intensification is worst....They expect it to intensify into a storm in 36 - 48 hrs....



they also said in the 1st advisory of Paula that she would not be a hurricane

I would watch the intensity of this system very closely; a weaker storm is likely to follow the NHC track, but if this intensifies further than predicted, that is where we could see that turn northward sooner and it missing land
Member Since: 10 Mars 2010 Posts: 1 Comments: 7874
Quoting CyclonicVoyage:
Here's the next recon flight, 8am EDT.

000
NOUS42 KNHC 201445
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1045 AM EDT WED 20 OCTOBER 2010
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 21/1100Z TO 22/1100Z OCTOBER 2010
TCPOD NUMBER.....10-141

I. ATLANTIC REQUIREMENTS
1. SUSPECT AREA (WESTERN CARIBBEAN)
FLIGHT ONE -- TEAL 70
A. 21/1200Z
B. AFXXX 0419A CYCLONE
C. 21/0800Z
D. 17.6N 81.5W
E. 21/1130Z TO 21/1530Z
F. SFC TO 15,000 FT


Not suspect anymore though, suspicions confirmed LOL
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694. HadesGodWyvern (Mod)
Japan Meteorological Agency
Tropical Cyclone Advisory #1
TROPICAL DEPRESSION 19
9:00 AM JST October 21 2010
=================================

SUBJECT: Tropical Depression Near Wake Island

At 0:00 AM UTC, Tropical Depression (1008 hPa) located at 19.1N 160.1E has 10 minute sustained winds of 30 knots with gusts of 45 knots. The depression is reported as moving north northwest at 17 knots

Dvorak Intensity:

Forecast and Intensity
=======================
24 HRS: 20.5N 156.1E - 35 knots (CAT 1/Tropical Storm)
Member Since: 24 mai 2006 Posts: 52 Comments: 46911
Quoting wunderkidcayman:
I think TD 19 will follow the oposite of the track I think it will go N the NW then WNW I think the track will be further N than what they have it

I said yesterday, that it would go to Cuba.
So, we are both wrong, apparently.
Member Since: Posts: Comments:
Here's the next recon flight, 8am EDT.

000
NOUS42 KNHC 201445
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1045 AM EDT WED 20 OCTOBER 2010
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 21/1100Z TO 22/1100Z OCTOBER 2010
TCPOD NUMBER.....10-141

I. ATLANTIC REQUIREMENTS
1. SUSPECT AREA (WESTERN CARIBBEAN)
FLIGHT ONE -- TEAL 70
A. 21/1200Z
B. AFXXX 0419A CYCLONE
C. 21/0800Z
D. 17.6N 81.5W
E. 21/1130Z TO 21/1530Z
F. SFC TO 15,000 FT
Member Since: 30 janvier 2010 Posts: 0 Comments: 3259
I think TD 19 will follow the oposite of the track I think it will go N the NW then WNW I think the track will be further N than what they have it
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Quoting CosmicEvents:
I'd say the blog did good!
We did nail the NHC discussion...And for once we agree with their forecast! Yikes!

It's all a Big Conspiracy, you know.
This blog was actually instigated by the NHC, and they just sit around drinking coffee(?), and let the blog do all the hard work.
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Quoting CosmicEvents:
I'd say the blog did good!
We did nail the NHC discussion...And for once we agree with their forecast! Yikes!


Agreed.
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If cyclogenesis is dificult to pronosticate, Intensification is worst....They expect it to intensify into a storm in 36 - 48 hrs....

Member Since: 2 août 2010 Posts: 21 Comments: 9882
I'd say the blog did good!
We did nail the NHC discussion...And for once we agree with their forecast! Yikes!
Member Since: 3 août 2005 Posts: 10 Comments: 5684
Quoting scott39:
Where does it go in the GOM if it survives? I know too soon! LOL


Too soon is right, way too soon LOL

Let's get through the weekend first because I suspect that this will hang around the NW Caribbean until then
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Quoting pottery:
Based on the current track models, it seems that the Shower Curtain Shield in Florida is holding up really well....


Seems like it however, that shower curtain will be burned at the stake this winter with a Strong La Nina in place. We really need a tropical shot before the dry season kicks in.
Member Since: 30 janvier 2010 Posts: 0 Comments: 3259
Quoting kmanislander:
Well, all the stuff we talked about in the past few hours is in the discussion, reformed center, slow meandering motion etc.

Only the watching remains now LOL
Where does it go in the GOM if it survives? I know too soon! LOL
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Based on the current track models, it seems that the Shower Curtain Shield in Florida is holding up really well....
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Well, all the stuff we talked about in the past few hours is in the discussion, reformed center, slow meandering motion etc.

Only the watching remains now LOL
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Now it gets FUN!!
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Quoting TropicalAnalystwx13:
Expected to make landfall on the Yucatan near hurricane status:



Considering it shouldn't take to Friday to become a TS, I'd say the NHC forecast intensity is a little low, and this could become a 75 mph - 80 mph hurricane.


Wait until the new models come out, should be interesting then.
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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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