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: 55 - 5

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

Quoting Neapolitan:
I would strongly disagree:

Click for larger image:

Appropriate tropical weather-related image


If the XTRP says it's a major, then I'll believe it :)

The cooler water and dry air should prevent a major hurricane in the gulf.

But I've been wrong before. Twice, in fact. :)
Member Since: Posts: Comments:
GFS showing the same pattern, just no storm.

Member Since: September 9, 2008 Posts: 6 Comments: 3414
the thing i find interesting...is that the blob isn't the hurricane in making..at least my thinking...correct me if i am wrong, but just to the sw of the blob is where the actual low is...and few clouds around it...but if you look at the visible loop...it has serious rotation...and in my limited knowlede..i would think that if that thing starts to get moisture from the blob...it will become the storm...please..i am new at this...am i correct?
Member Since: Posts: Comments:
Good Morning, it seems to really be quieting down in tropics with the exception of Invest 99.

It's in the same location where Hurricane Lenny formed in Nov of 1999, but the steering currents are different.
Member Since: Posts: Comments:
Richard turning south
Member Since: Posts: Comments:
Quoting cat5hurricane:

Then it's probably not the model the NHC is currently going off of since they are anticipated a mid-level ridge to establish over FL through next Tuesday.


No, that's exactly it, imo.

Notice the ridging over FL. Step through the loop and watch it.

Loop

Member Since: September 9, 2008 Posts: 6 Comments: 3414
Quoting oracle28:


GOM is too cool for a Major, IMO.
I would strongly disagree:

Click for larger image:

Appropriate tropical weather-related image
Member Since: Posts: Comments:
Quoting bjdsrq:


Yeah, this thing is screwed once it gets north of Cozumel's lat.


The GFDL model solution, while low % at this time for that time frame, is that the ridging moves E and he rides around the left edge. Kind of like Paula, just further N.
Member Since: September 9, 2008 Posts: 6 Comments: 3414
Quoting rmbjoe1954:


Thanks. I should have read your previous post. Wow the models are aggressive in taking future Richard as a major into the GOM.


GOM is too cool for a Major, IMO.
Member Since: Posts: Comments:
Quoting Neapolitan:

Yes, they would. Vertically-sheared cyclones can not only maintain, but grow (and, in fact, undergo rapid intensification due to a combination of factors). I'm not saying they will classify...but the shear alone shouldn't stop them from doing so.


Alberto in 2006.
Member Since: July 1, 2008 Posts: 13 Comments: 7340
Quoting Seastep:
Based on the clear LLC, I'd say it is a TS now. Just naked, atm.

Would they classify it being a naked swirl, given that it does have plenty of convection associated with it, just not over the center?

Yes, they would. Vertically-sheared cyclones can not only maintain, but grow (and, in fact, undergo rapid intensification due to a combination of factors). I'm not saying they will classify...but the shear alone shouldn't stop them from doing so.
Member Since: Posts: Comments:
41. IKE
Recon getting there...Link
Member Since: Posts: Comments:
Quoting Jax82:
I like blue over FL :) and 99L is caught in a Dry air sandwich.



Yeah, this thing is screwed once it gets north of Cozumel's lat.
Member Since: Posts: Comments:
Quoting reedzone:


Like I said, whatever is left of 99L, should get pulled northward. If the storm is as major as some models say it could be, and if it speeds north, it may not weaken as rapidly and we could have a big problem, however, it is a long shot as of right now, but a potential scenario.


Thanks. I should have read your previous post. Wow the models are aggressive in taking future Richard as a major into the GOM.
Member Since: June 16, 2005 Posts: 0 Comments: 1177
17.8N/82.5W

Flash Loop

Member Since: September 9, 2008 Posts: 6 Comments: 3414
The CMC, GFDL and HWRF all have Richard moving into the GOM although it is still early in development. I just hope it comes to the northern gulf coast as a big rain event with no wind.
Member Since: Posts: Comments:
Quoting rmbjoe1954:


Hi Alan-

Do you see this as a potential threat to Florida once it gets east of the Yucatan?


Like I said, whatever is left of 99L, should get pulled northward. If the storm is as major as some models say it could be, and if it speeds north, it may not weaken as rapidly and we could have a big problem, however, it is a long shot as of right now, but a potential scenario.
Member Since: July 1, 2008 Posts: 13 Comments: 7340



Support for a strong storm in the GOM is possible!
Member Since: Posts: Comments:
Quoting reedzone:
99L is getting affected most by high wind shear to the west, you can see it as the clouds get pulled eastward. Dry air is NOT a big inhibiting factor, remember Paula? Strengthened to a Category 2 Storm while dry air surrounded the tiny system.


Hi Alan-

Do you see this as a potential threat to Florida once it gets east of the Yucatan?
Member Since: June 16, 2005 Posts: 0 Comments: 1177
6z GFDL






6z HWRF



Member Since: June 9, 2007 Posts: 4 Comments: 15776
Shear is forecast to relax and I expect this to be Tropical Storm Richard most likely tomorrow. I really don't see dry air choking the storm out, I tend to agree with the loop to Belize, not buying the Yucatan Channel track just yet, though eventually in time, as a trough swings by next week, should pull what's left of 99L northward. Some decent rains is coming to the Southeast soon, it will be some time though.
Member Since: July 1, 2008 Posts: 13 Comments: 7340
Quoting reedzone:
99L is getting affected most by high wind shear to the west, you can see it as the clouds get pulled eastward. Dry air is NOT a big inhibiting factor, remember Paula? Strengthened to a Category 2 Storm while dry air surrounded the tiny system.


Paula was one of those unusual systems that had a nice tiny core, but its small size was affected by the dry air.
Member Since: Posts: Comments:
29. IKE
Quoting cat5hurricane:

Whole lotta dry air closing in on it.


That's what I see too.

Not sure about 99L and it's future. But I'm an amateur.


Quoting portcharlotte:
Ike, do you remember tje "Pattern Change"? Did you see it?


Yeah...it blew by here about 7 weeks ago.
Member Since: Posts: Comments:
Based on the clear LLC, I'd say it is a TS now. Just naked, atm.

Would they classify it being a naked swirl, given that it does have plenty of convection associated with it, just not over the center?

Don't recall this situation with an unclassified storm.
Member Since: September 9, 2008 Posts: 6 Comments: 3414
"The pattern change is coming"



Member Since: June 9, 2007 Posts: 4 Comments: 15776
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
Member Since: October 1, 2007 Posts: 81 Comments: 26511
99L is getting affected most by high wind shear to the west, you can see it as the clouds get pulled eastward. Dry air is NOT a big inhibiting factor, remember Paula? Strengthened to a Category 2 Storm while dry air surrounded the tiny system.
Member Since: July 1, 2008 Posts: 13 Comments: 7340
Morning all. Invest 99L is having a hard time it appears with Shear from the West. As Dr. Masters pointed out shear will probably ease some in the next 24hrs. I find it funny how some on here post 1 model that takes it into the GOM when most models have it looping back toward South America. Oh Well!
Member Since: Posts: Comments:
Tropical Update Oct. 20th. 2010
Member Since: Posts: Comments:
Hey PensacolaDoug! :)

Is it too soon to know anything for certain about 99L and its future?

WTH is that one model showing it as a Cat 4 in the Gulf? That cannot be right, can it?
Member Since: Posts: Comments:
Ike, do you remember tje "Pattern Change"? Did you see it?
Member Since: Posts: Comments:
I like blue over FL :) and 99L is caught in a Dry air sandwich.

Member Since: September 2, 2008 Posts: 1 Comments: 1261
17. IKE
99L on water vapor...Link
Member Since: Posts: Comments:
The drought here in SW Florida is getting to be a major concern. No rain has been recorded in October and some parts are going into 6 weeks without rain! Some tropical moisture would be a welcome situation since we are going into the dry season. There is nothing scary about a tropical storm bringinh rain to Florida...we need it...especially when thr wells run dry.
Member Since: Posts: Comments:
Invest 99L
18Oct 12pmGMT - 14.1n81.8w - 25knots - 1010mb - ATCF*15.1n82.5w*15.0n82.4w*14.1n81.9w
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 - 1007mb - ATCF
* Before NHC reevaluated&revised the ATCF numbers
20knots=~37km/h _ 25knots=46.3km/h _ 30knots=~55.6km/h

Copy&paste 14.1n81.8w, 14.6n82.3w, 15.3n82.8w, 16.0n83.1w, 16.7n83.3w-17.4n83.4w, 17.4n83.4w-17.7n83.2w, 17.7n83.2w-17.8n82.9w, 17.8n82.9w-17.7n82.5w, ctm, cyo into the GreatCircleMapper for a look at the last 24^hours
Member Since: August 21, 2007 Posts: 0 Comments: 4860
Quoting hamla:
looks lik we gonna get richard and hope that it stays a fish storm

Its not a fish storm it even doesn't rain fish
Member Since: Posts: Comments:
Member Since: Posts: Comments:
Upper level winds probably will not be condusive for 99L today.
Member Since: June 13, 2009 Posts: 0 Comments: 6728
Thank you for the update, Doc.
Member Since: January 6, 2009 Posts: 0 Comments: 217
Quoting hamla:
looks lik we gonna get richard and hope that it stays a fish storm


How can this be a fish storm? Do you know how many people live on islands anywhere this system can go?
Member Since: Posts: Comments:
Quoting hamla:
looks lik we gonna get richard and hope that it stays a fish storm
land fish??
Member Since: June 13, 2009 Posts: 0 Comments: 6728
Quoting hamla:
looks lik we gonna get richard and hope that it stays a fish storm


It can not be a fish storm


Member Since: Posts: Comments:
Recon
13:33:30Z 21.733N 86.133W 392.1 mb
(~ 11.58 inHg) 7,711 meters
(~ 25,299 feet)
Member Since: January 30, 2010 Posts: 0 Comments: 3259
Member Since: July 12, 2007 Posts: 0 Comments: 5995

Viewing: 55 - 5

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.