Little change to 99L, which remains very close to tropical depression status
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
Reader Comments
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If you're gonna do a proper poll, you have to allow for every possibility. (Hint: ranges work better than absolutes.) At any rate, my answer--as it was the other day--f) 0%
Baby steps, but I am sure they have noticed, hence the language stating that a TD could form at any time tonight or tomorrow.
I say d) 10%.
Pretty darn unlikely that 99L will be our last named storm to me. Still plenty warm out there, and good conditions. La Nina years usually crank out a storm in November and December (2003, 2007, 1995, ect)
we will end this season with 19 named storms as i predicted earlier this year. http://www.wunderground.com/blog/Twinkster/show.html
Well, not really; odds or for the next 48 hours, so the increase in odds mean they're recognizing that conditions for development will improve...
Thanks. Winds very calm here now ( 4 mph ) out of the ENE and NE which pretty much confirms a new center to the SE of Grand Cayman. I suspect that once the HH gets in that deep convection we are going to see TS force winds.
Tampa Shield GONE!!
We're gonna have ta try diverting tha warp engines Cap'n!
I have been trying to make my avatar like Neopolitans but my blond hair keeps getting in the way...My hubby keeps saying"You are a true blonde, Live with it
have pretty much nailed it, the waters are still very warm out there and it is probable we'll see at least 2 more after Richard, Shary and Tomas, to give us a grand total of 19..
AS OF 2100 UTC...A 1006 MB LOW IS CENTERED S OF THE CAYMAN
ISLANDS NEAR 17N81W.
Yep, that is the position I had it at from about 4 pm today
210. kmanislander 9:16 PM GMT on October 20, 2010
Quoting whadat:
Yep. gregmerren. This system is killing me - don't know whether to do all out prep with the big boat or just expect marginal TS winds. If it does get going I probably won't have anytime to do much.
Ah, that explains it it LOL
Run this loop and you will see the old center virtually disappear from view into the deep convection located at 17 N and 81 W. This strongly suggests that a center relocation is underway but I won't know for sure until I see another 4 frames or so load and run. Regardless, the steering will remain weak for the next couple of days so this is unlikely to come up on us quickly even if it develops.
From where it is now the more likely track is to the WNW but we are not out of the woods yet.
Hard to say whether to prep or not because this time of year they can go anywhere but all indications are for very slow motion at least through 24 hours.
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Member Since: August 19, 2006 Posts: 0 Comments: 12172
That would make sense, if this were a month ago.
B
why doesn't it make sense now. Wilma hit florida as a cat 3 in late october. A major hurricane as depicted by HWRF is not entirely out of question
Tropical Update From Texas!
Tropical Update: Invest 99L Likely to become Richard; Shary Possible; Western Pacific Firing Up, With Video!
99L likely to become Tropical Storm Richard 10/20/10
Wilma hit in 2005 when there had been no cold fronts and no dry air over the Gulf prior to its arrival.
The weather patterns and temperature regime in that year were 2-3 weeks behind the average for that time of year in that year, unlike this year when the reverse has been true. This year, we spent nearly three whole weeks enjoying very dry and cool conditions here in Central Florida and the SSTs are much lower as a result.
Also, Wilma hit in extreme SW Florida, not just south of Tampa. As it turned out, the first significant cold front of the season followed Wilma's passage. That was a blessing to people who were without power across many areas of S. FL, because at least they did not have to suffer through days upon days of heat and humidity.
In 2005, the upper air patterns right through until just after Wilma came through were also much more favorable for tropical cyclones to venture as far north as the Florida Peninsula. This year they have been very hostile and the subtropical jet has made an early appearance. That also was not the case in '05 until after Wilma.
Wind shear may relax a bit over the Gulf next week but I doubt that it will be nonexistent, which it would just about have to be to support such a powerful hurricane as depicted by the HWRF model.
Lots of work ahead if it wants to grow up, but it seems to be trying!
AL, 99, 2010102100, , BEST, 0, 176N, 812W, 30, 1006, LO, 34, NEQ, 0, 0, 0, 0, 1011, 220, 70, 0, 0, L, 0, , 0, 0, INVEST, M,
If that model comes true, it would be the THIRD time a storm hit Belize this year.
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