Western Caribbean disturbance 99L near tropical depression strength
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
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What a way to start the day...
13:33:30Z 21.733N 86.133W 392.1 mb
(~ 11.58 inHg) 7,711 meters
(~ 25,299 feet)
It can not be a fish storm
How can this be a fish storm? Do you know how many people live on islands anywhere this system can go?
Its not a fish storm it even doesn't rain fish
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
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?
Numerous models calling for a Cat 4-5 Storm into the GOM
AOI
TS BUSTED FORECAST ALIBI
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.
That's what I see too.
Not sure about 99L and it's future. But I'm an amateur.
Yeah...it blew by here about 7 weeks ago.
Paula was one of those unusual systems that had a nice tiny core, but its small size was affected by the dry air.
6z HWRF
Hi Alan-
Do you see this as a potential threat to Florida once it gets east of the Yucatan?
Support for a strong storm in the GOM is possible!
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.
Flash Loop
Thanks. I should have read your previous post. Wow the models are aggressive in taking future Richard as a major into the GOM.
Yeah, this thing is screwed once it gets north of Cozumel's lat.
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.
GOM is too cool for a Major, IMO.
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.
Click for larger image:
No, that's exactly it, imo.
Notice the ridging over FL. Step through the loop and watch it.
Loop
It's in the same location where Hurricane Lenny formed in Nov of 1999, but the steering currents are different.
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