Western Caribbean disturbance 99L near tropical depression strength

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

Share this Blog
2
+

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

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: 155 - 105

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10Blog Index

I wouldn't be surprised to see a decouple this afternoon and a regen down by the center.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
The high winds being seen are all located in the deep convection just to the West of Jamaica and well removed from the center of 99L. The readings are almost certainly gusts.

Compare the coordinates with the satellite imagery using the lat/lon feature

There will be no TD classification based upon this data.
Member Since: August 19, 2006 Posts: 0 Comments: 15842
Quoting SweetHomeBamaGOM:



because it is a low level closed circulation. the upper levels are currently aligning, i think...?


Flight level was < 900ft. Doesn't make sense IMO either...
Member Since: Posts: Comments:
Quoting VAbeachhurricanes:


how can the flight level be 26mph and the surface be 46?


The cyclone is not stacked. Max flight level winds are most likely with the convection to the E & NE.

Man, shear is still kicking hard on visible. Almost looks like it increased a bit.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
Now shear is kicking 99Ls butt, I doubt they do any sort of upgrade

In fact the center is moving south while the convection is being blown off to the northeast
Member Since: Posts: Comments:
Quoting VAbeachhurricanes:


how can the flight level be 26mph and the surface be 46?



because it is a low level closed circulation. the upper levels are currently aligning, i think...?
Member Since: Posts: Comments:
Member Since: Posts: Comments:
what is generally going to be required for this invest to start throwing up convection around the closed circulation?
Member Since: Posts: Comments:
Quoting CyclonicVoyage:
16:09:30Z 17.983N 80.583W

40 knots
(~ 46.0 mph)


how can the flight level be 26mph and the surface be 46?
Member Since: Posts: Comments:
40 knots
(~ 46.0 mph) strongest surface winds so far uncontaminated!
Member Since: Posts: Comments:
Quoting scooster67:
If you think opinion's make people "quacks" why are you hanging around in their blog?


Been hangin for a good bit. A sarcastic remark, didn't mean to offend. There's actually a good bit of intelligence around. If you read through what I was saying a good show is about to happen.
Member Since: Posts: Comments:
Last run posted sustained TS winds like yesterday.

They may call it if the circulation is confirmed as better organized...
Member Since: Posts: Comments:
Quoting TOMSEFLA:
has levi posted today?


No he hasn't but you can check his blog yourself if you need to.

Link
Member Since: October 12, 2010 Posts: 0 Comments: 48
16:09:30Z 17.983N 80.583W

40 knots
(~ 46.0 mph)
Member Since: January 30, 2010 Posts: 0 Comments: 3259
16:01:30Z 17.517N 80.617W 980.9 mb
(~ 28.97 inHg) 257 meters
(~ 843 feet) 1010.2 mb
(~ 29.83 inHg) - From 164° at 24 knots
(From the SSE at ~ 27.6 mph) 23.4°C
(~ 74.1°F) 17.6°C
(~ 63.7°F) 25 knots
(~ 28.7 mph) 31 knots
(~ 35.6 mph) 7 mm/hr
(~ 0.28 in/hr)
Member Since: Posts: Comments:
has levi posted today?
Member Since: Posts: Comments:
LOL! Little slow on the trigger today, IKE!
Member Since: Posts: Comments:
137. IKE
...
Member Since: Posts: Comments:
1st VORTEX:

Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 20th day of the month at 16:08Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 309)
Mission Purpose: Investigate eight suspect area (flight in the North Atlantic basin)
Mission Number: 2
Observation Number: 08
A. Time of Center Fix: 20th day of the month at 15:33:40Z
B. Center Fix Coordinates: 17°20'N 82°01'W (17.3333N 82.0167W)
B. Center Fix Location: 142 miles (229 km) to the SSW (197°) from George Town, Cayman Islands (GBR).
C. Minimum Height at Standard Level: Not Available
D. Estimated (by SFMR or visually) Maximum Surface Wind: 23kts (~ 26.5mph)
E. Location of the Estimated Maximum Surface Wind: 23 nautical miles (26 statute miles) to the ESE (121°) of center fix
F. Maximum Flight Level Wind Inbound: From 247° at 11kts (From the WSW at ~ 12.7mph)
G. Location of Maximum Flight Level Wind Inbound: 28 nautical miles (32 statute miles) to the ESE (115°) of center fix
H. Minimum Sea Level Pressure: 1009mb (29.80 inHg) - Extrapolated
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 25°C (77°F) at a pressure alt. of 274m (899ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 25°C (77°F) at a pressure alt. of 273m (896ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 18°C (64°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Not Available
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Wind, Pressure and Temperature
N. Fix Levels (sfc and flt lvl centers are within 5nm of each other): Surface and 1,500 feet
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 0 nautical miles
Remarks Section:
Maximum Wind Outbound: 24kts (~ 27.6mph) in the east quadrant at 15:54:50Z
Maximum Flight Level Wind: 24kts (~ 27.6mph) in the east quadrant at 15:54:50Z
Sea Level Pressure Extrapolation From: Below 1,500 feet
Maximum Flight Level Temp: 24°C (75°F) which was observed 7 nautical miles to the ESE (122°) from the flight level center

Member Since: Posts: Comments:
If you think opinion's make people "quacks" why are you hanging around in their blog?
Member Since: Posts: Comments:
Quoting cat5hurricane:

Not gonna object to that. They have been bone dry. Even a drop of rain would be welcome.


Amen!
Member Since: Posts: Comments:
Quoting Floodman:


Trust me, it's only entertaining for a short while...


priceless. If i hear one more xtrap joke i may puke. However, I must admit that "convention is not building around the center yet" ----OOOPS!
Member Since: Posts: Comments:
131. MahFL
I think the center is just rotating around the general broad cirulation.
Member Since: Posts: Comments:
Quoting SweetHomeBamaGOM:
i get the feeling some people in here aren't as meteorologically inclined as others, so they become wishcasters. once they are wishcasters they are no better than someone betting randomly on a roulette table. some of the same voices who just a month ago were calling for every storm to come CONUS as a major are now downcasting. it's kind of entertaining to watch. lol


Trust me, it's only entertaining for a short while...
Member Since: August 2, 2006 Posts: 10 Comments: 9922
Quoting IKE:
1009.4 mb
(~ 29.81 inHg)

Member Since: Posts: Comments:
AMZ089-202130-
SYNOPSIS FOR CARIBBEAN SEA AND TROPICAL N ATLC FROM 07N TO 22N
BETWEEN 55W AND 65W
1130 AM EDT WED OCT 20 2010

.SYNOPSIS...LOW PRES 1007 MB NEAR 18N82W DRIFTS SLOWLY S THROUGH
FRI THEN MOVES W INTO CENTRAL AMERICA NEAR HONDURAS AND
NICARAGUA OVER THE WEEKEND...POSSIBLY AS A TROPICAL CYCLONE.

http://www.nhc.noaa.gov/text/MIAOFFN05.shtml

Member Since: Posts: Comments:
125. IKE
1009.4 mb
(~ 29.81 inHg)
Member Since: Posts: Comments:
My guess is pressure is 1010-1011 at the moment in 99L
Member Since: Posts: Comments:
Quoting Ryuujin:


But..But... This season is over, and a fork stuck in it, according to some of the casters here on the blog! So there is no way that can happen!


It ain't over till its OVER! :P People will be people. Look at the trend, we should have 1 more named storm after this as the Caribbean remains favorable for mischief.

My prediction from May - 18/9/5

TOTALS (so far) - 16/9/5
Member Since: Posts: Comments:
The rains of low pressure in the Caribbean, are also affecting eastern Cuba, where Nicole left the soil saturated.
Member Since: Posts: Comments:
Product: Air Force Tropical RECCO Message (URNT11 KNHC)
Transmitted: 20th day of the month at 15:29Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 309)
Mission Purpose: Investigate eight suspect area (flight in the North Atlantic basin)
Mission Number: 2
Observation Number: 07

Mandatory Data...

Observation Time: Wednesday, 15:24Z
Radar Capability: Yes
Aircraft Altitude: Below 10,000 meters
Coordinates: 17.1N 81.6W
Location: 153 miles (246 km) to the S (185°) from George Town, Cayman Islands (GBR).
Turbulence: None
Conditions Along Flight Route: In the clear
Pressure Altitude: 270 meters
Flight Level Wind: From 260° at 10 knots (From the W at ~ 11.5 mph)
- The above is a spot wind.
- Winds were obtained using doppler radar or inertial systems.
Flight Level Temperature: 23°C
Flight Level Dew Point: 18°C
Weather (within 30 nautical miles): Thunderstorm(s)
Mean Sea Level Pressure (MSLP): 1010 mb (extrapolated)

Optional Data...

Estimated Surface Wind: From 240° at 15 knots (From the WSW at ~ 17.2 mph)

Remarks Section...

Surface Wind Speed (likely by SFMR): 16 knots (~ 18.4mph)
Member Since: Posts: Comments:
GFS has been the most accurate model but it has had some issues in the Western and Middle Caribbean Sea. Don't think we'll have a better understanding of 99L's path for at least another 24 hours.
Member Since: Posts: Comments:
Quoting cat5hurricane:

Not gonna object to that. They have been bone dry. Even a drop of rain would be welcome.


i dont know if i am reading it right but it kinda looks like there will still be drought here in fla panhandle?
Member Since: Posts: Comments:
117. Jax82
Negative NAO currently and for a while.
Member Since: Posts: Comments:
Quoting TOMSEFLA:
waiting on levi update..........



same here...come on Levi !!
Member Since: Posts: Comments:
Quoting Orcasystems:
Complete Update

Numerous models calling for a Cat 4-5 Storm into the GOM



AOI
AOI AOI AOI

AOI AOI AOI

TS BUSTED FORECAST ALIBI


But..But... This season is over, and a fork stuck in it, according to some of the casters here on the blog! So there is no way that can happen!
Member Since: August 20, 2010 Posts: 0 Comments: 373
Member Since: Posts: Comments:
112. cre13
Quoting cat5hurricane:

Not gonna object to that. They have been bone dry. Even a drop of rain would be welcome.


Bone dry? We got 11" just a couple weeks ago from an extra (or was it sub?) tropical storm. We were definitely bone dry prior to that, though. Right now, a lot of rain is the last thing we need.

By the way, I'm in northeastern NC so what I'm saying only applies to here of course. I don't know about the rest of the region.

I hope if it does bring us rain, that it's only a small amount.
Member Since: Posts: Comments:
This talk of a “major” is ridiculous without being named, Come on, MAN. I agree 99l is much better organized this morning. I also agree the exposed LLC is only temporary and the current convection burst will continue throughout the day as he moves to protect itself from the dry air he’s boxed into. But the models are struggling with this storm in its current state and we won’t see a better solution until tomorrow or later. Yes, he may continue to build despite the hostile environment and become named, then maybe, as shear decreases to its north, it could latch onto a steering ridge which may allow it to move to the north and then east as is traditional and as some models might suggest. However troublesome, given the current long term setup, the scenario of a major event being “somewhat likely” is long shot at this point and track and intensity is anyone’s guess. But really, ..really!, ..no really!! a major hitting the US. COME ON, Mann, get a grip. Interest in FL and the Caribbean should remain vigilant and keep abreast with the NHC, (not a bunch of amateur quacks!) for any potential developments.
Member Since: Posts: Comments:
i get the feeling some people in here aren't as meteorologically inclined as others, so they become wishcasters. once they are wishcasters they are no better than someone betting randomly on a roulette table. some of the same voices who just a month ago were calling for every storm to come CONUS as a major are now downcasting. it's kind of entertaining to watch. lol
Member Since: Posts: Comments:
Quoting scott39:
It sure looks like it.


Here's why. 99L basically stranded where the steering is virtually non existent. This would promote meandering around which is what we are seeing.

Member Since: August 19, 2006 Posts: 0 Comments: 15842
Quoting kmanislander:


No it won't because the anticyclone that is shearing it is moving to the N and will then impart NW shear over 99L. To me it would appear the system is sagging straight to the South now in the visible loop
It sure looks like it.
Member Since: June 13, 2009 Posts: 0 Comments: 6860
waiting on levi update..........
Member Since: Posts: Comments:
Anyway I am out for now. Will check back later.
Member Since: August 19, 2006 Posts: 0 Comments: 15842

Viewing: 155 - 105

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10Blog 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.