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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Quoting Waltanater:
Excellent! Good luck to you and your studies there. FIU is a great university and is it ever growing!
Thank you! speaking of studies, that's what i'm going to do now. Physics exam tomorrow.... Gross. Later everyone.
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good afternoon every body .....the models still look like a spider web lol
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Coincidentally, today's Wiki feature article is on an October looper, the 1910 Cuba Hurricane
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Quoting Waltanater:
Holy Crap!
This isn't twitter.
We don't need to know what you're doing every moment.....:)
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Quoting WStormW:
Just wanted to say hello. Have a great day!


welcome back buddy...we missed ya
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Quoting lightningbolt73:
I don't mean to be a pest, but I've asked 2 questions about posting on here and none of them have been answered! I'm not a troll I'm a totally blind new user who wants to enjoy posting just like evryone else!


You can adjust what you see using the filter at the top of the comments box. i.e. "see all", "see bad", etc. Didn't see your other question. What was it?
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Quoting kmanislander:


Look at post 106. The center would have to be, and always has been, to the West of that buoy all day to get those wind direction readings. A SW or WSW wind is the result of the flow around the Southern side of the low center coming up from the SW
Sorry I was judging WSW by the elongated inflow I'm seeing on satellite. Since the reading has been like that since this morning, you are correct. I think a relocation is coming farther east though.
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Quoting shawn26:
When is the next hurricane hunter mission?
8 pm tonight.
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99L's Surface circulation is beginning its entrance into the heavy thunderstorms.
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Quoting CybrTeddy:
Watch this loop, check out what the COC has been doing. It has been removed from the convection, and has broadened out and unwinding considerably in the last few frames, but has rapidly been moving southward. There is likely a COC developing where kman thinks it might be.
Link


Yep and we should see RI soon enough now. The CoC is trying to move to a better environment.
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Quoting SouthDadeFish:
Yes they did, its only a few years old and pretty small for some reason. Dr. Hugh Willoughby leads the program and I'm currently taking a Hurricanes class taught by him this semester. Very interesting and fun!
Excellent! Good luck to you and your studies there. FIU is a great university and is it ever growing!
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Quoting Jeff9641:


I think the GFDL seems more realistic.


More realistic but still not highly realistic.

Remember what Levi said. The GFDL and HWRF both have a poleward bias in the early model runs. That will likely be altered once this officially becomes a TC.

And the earlier runs for both models were showing no land interaction at all.

I'm thinking that both models have other biases in their program and which come out in a situation like this, where a system is in the early formative stages.

You may call me a downcaster but if this were mid-August through late September or if it were 2005 I'd be likely keeping quiet on these points.
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Quoting Jeff9641:


I agree it gets a little much after awhile and when you say something that the models are showing then you get slammed for it. I think a FL landfall of a hurricane maybe a very very real possibility next week.
Jeff, I wasn't hassling you yesterday, just saying not to get overzealous. McLuvincane heckled me for that (and my name LOL). I like the way you word it this time....."maybe a very very real possibility next week" Maybe being the key word. On another note, what is it with the models always throwing Florida into the mix on almost every early run of every model? Sometimes that is a good omen for us because the models change so much that we end up out of the mix in the end. Wilma was a once in a few decades type of storm and the chance of that happening again are low, not impossible but low. I think the front coming to pick up this system is going to be a stronger one than the previous ones and will probably rip it up as it moves NE. Always prepare for the worst and hope for the best!!
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Quoting SouthDadeFish:
Well either the reading is faulty or the center is NE of that location.


Look at post 106. The center would have to be, and always has been, to the West of that buoy all day to get those wind direction readings. A SW or WSW wind is the result of the flow around the Southern side of the low center coming up from the SW
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Watch this loop, check out what the COC has been doing. It has been removed from the convection, and has broadened out and unwinding considerably in the last few frames, but has rapidly been moving southward. There is likely a COC developing where kman thinks it might be.
Link
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109. HadesGodWyvern (Mod)
India Meteorological Department
Tropical Cyclone Bulletin #2
DEPRESSION BOB04-2010
23:30 PM IST October 20 2010
================================

SUBJECT: Depression Over East Central Bay Of Bengal

At 18:00 PM UTC, Depression BOB04-2010 over east central Bay of Bengal remained practically stationary and lays centered over the same areas near 17.5N 91.5E, or about 350 km south-southwest of Sittwe Myanmar, 450 km south of Cox Bazar Bangladesh, and 650 km southeast of Digha West Bengal.

The current environmental conditions and numerical weather prediction models suggest that the system would intensify further into a deep depression. It would move initially northwards and then north-northeastwards towards north Myanmar and south Bangladesh coasts during next 48 hours.

Since the system is likely to move towards north Myanmar and south Bangladesh coasts, it is not expected to affect east coast of India.
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Quoting kmanislander:


I don't see that. The wind has been out of the WSW there for quite some time.
Well either the reading is faulty or the center is NE of that location.
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Quoting shawn26:
When is the next hurricane hunter mission?


8pm EDT tonight. Should start descending around 7:30.
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Wind direction at 42057 since early this morning. All out of the SW or WSW

MM DD TIME
(EDT) WDIR WSPD
kts GST
kts WVHT
ft DPD
sec APD
sec MWD PRES
in PTDY
in ATMP
F WTMP
F DEWP
F SAL
psu VIS
nmi TIDE
ft
10 20 1:50 pm WSW 11.7 13.6 3.3 5 4.1 - 29.78 -0.07 82.0 84.0 75.0 - - -
10 20 12:50 pm SSW 13.6 17.5 3.3 5 4.0 - 29.82 -0.02 79.2 83.8 77.2 - - -
10 20 11:50 am SW 13.6 19.4 3.0 5 4.0 - 29.84 0.01 79.9 83.8 76.1 - - -
10 20 10:50 am SSW 13.6 17.5 3.3 5 4.0 - 29.85 0.04 80.2 83.8 75.6 - - -
10 20 9:50 am SW 13.6 17.5 3.3 6 4.0 - 29.83 0.05 82.2 83.8 74.7 - - -
10 20 8:50 am SW 11.7 15.5 3.3 5 4.0 - 29.83 0.05 81.7 83.7 74.3 - -
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Wondering where the south movement is coming from? Looks east to me.

Member Since: 30 janvier 2010 Posts: 0 Comments: 3259
Thanks for the link Stormchaser2007...great site!
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When is the next hurricane hunter mission?
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Quoting WStormW:
Just wanted to say hello. Have a great day!


Hello StormW. Nice to see you here!!!!
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Quoting SouthDadeFish:
Nice catch, as it implies the center is to the NE of that location.


I don't see that. The wind has been out of the WSW there for quite some time.
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Quoting oracle28:


The XTRP model has been all over the place lately. It was due east this AM, now it's SE. odd....
Looks like the shear relaxes some in the GOM within 72 hours.
Member Since: 13 juin 2009 Posts: 0 Comments: 6912
Quoting lightningbolt73:
I don't mean to be a pest, but I've asked 2 questions about posting on here and none of them have been answered! I'm not a troll I'm a totally blind new user who wants to enjoy posting just like evryone else!


I don't see them. Can you provide the post numbers?

Edited: Also, many times there may not be someone on that is able to answer your question accurately.
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Quoting oracle28:


The XTRP model has been all over the place lately. It was due east this AM, now it's SE. odd....


I cant wait until the 18z run of the XTRP comes out.

Highly valuable model.

(Sarcasm)

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Quoting Seastep:
Did you take note of the 2hr wind direction at that buoy, kman?
Nice catch, as it implies the center is to the NE of that location.
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Quoting Stormchaser2007:
Personally, I think the ECMWF solution wlll come very close to verifying.

Landfall somewhere on the Yucatan, then what ever is left could be drawn NE. Probably nothing more than a remnant low or depression.





The XTRP model has been all over the place lately. It was due east this AM, now it's SE. odd....
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Quoting Seastep:
Did you take note of the 2hr wind direction at that buoy, kman?


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I don't mean to be a pest, but I've asked 2 questions about posting on here and none of them have been answered! I'm not a troll I'm a totally blind new user who wants to enjoy posting just like evryone else!
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Well well.. look who finally got the hint and came onboard. ECMWF.


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Quoting Waltanater:
So they finally created a MET school then. When I went there years ago, they didn't have one. hmmm...maybe I can still enroll. LOL
Yes they did, its only a few years old and pretty small for some reason. Dr. Hugh Willoughby leads the program and I'm currently taking a Hurricanes class taught by him this semester. Very interesting and fun!
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Did you take note of the 2hr wind direction at that buoy, kman?
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Quoting TropicalMan2010:

over cancun as cat 2 seems more reasonable than the strength of the hwrf which is insane


Except that it is basically the same as the HWRF in terms of intensity. The lower intensity is because of land interaction. Same model run just prior to landfall in the Yucatan.

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The current center of 99L is located about 30 miles to the WNW of this buoy which indicated a pressure of 1007.5 mbs an hour ago. A pretty good read of the system and hopefully the data will update before too long so that we can see if the pressure has bottomed out.

99L is a prime candidate for a center relocation to the deep convection off to the East near Jamaica but the motion to the South is bringing it underneath the high that is shearing it off and this may allow the current center to reorganize and prevent a relocation.

Many moving parts out there with this one.

Wind Speed (WSPD): 13.6 kts
Wind Gust (GST): 15.5 kts
Wave Height (WVHT): 3.3 ft
Dominant Wave Period (DPD): 5 sec
Average Period (APD): 4.0 sec
Atmospheric Pressure (PRES): 29.75 in
Pressure Tendency (PTDY): -0.09 in ( Falling Rapidly )
Air Temperature (ATMP): 81.9 °F
Water Temperature (WTMP): 84.2 °F
Dew Point (DEWP): 75.7 °F
Heat Index (HEAT): 88.9 °F
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Quoting Jeff9641:


That is why I said tomorrow. Past 5 days this should really pick up forward speed as the trough moves in. Either way a much need rain event seems to be coming to FL later this weekend and into next week.
I wouldn't be so sure on a Florida track yet. It's very possible, but still so many other scenarios, including a 30% chance of Richard never forming according to the NHC. We'll see ;~)
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85. 7544
i dont see why people get upset when we compare this to wilma it seems to be heading that the same track thru the yucatan then ne to fla so im saying this could be another wilma and maybe alot sronger next
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Quoting SouthDadeFish:
Yes I do. I'm currently an undergraduate student at Florida International University, studying meteorology.
So they finally created a MET school then. When I went there years ago, they didn't have one. hmmm...maybe I can still enroll. LOL
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470

WHXX01 KWBC 201814

CHGHUR

TROPICAL CYCLONE GUIDANCE MESSAGE

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL

1814 UTC WED OCT 20 2010



DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.

PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE

AND SUBTROPICAL CYCLONE INFORMATION.



ATLANTIC OBJECTIVE AIDS FOR



DISTURBANCE INVEST (AL992010) 20101020 1800 UTC



...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...

101020 1800 101021 0600 101021 1800 101022 0600



LAT LON LAT LON LAT LON LAT LON

BAMS 17.1N 82.2W 16.9N 82.1W 16.2N 82.3W 15.2N 82.9W

BAMD 17.1N 82.2W 17.5N 81.5W 17.6N 81.3W 17.7N 81.6W

BAMM 17.1N 82.2W 16.8N 82.0W 16.3N 82.3W 15.7N 83.0W

LBAR 17.1N 82.2W 17.2N 81.5W 17.9N 81.3W 19.1N 81.4W

SHIP 30KTS 32KTS 35KTS 38KTS

DSHP 30KTS 32KTS 35KTS 38KTS



...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...

101022 1800 101023 1800 101024 1800 101025 1800



LAT LON LAT LON LAT LON LAT LON

BAMS 14.4N 83.7W 12.9N 85.7W 13.0N 88.1W 14.4N 90.2W

BAMD 17.8N 82.3W 17.4N 85.1W 17.3N 89.7W 18.2N 92.9W

BAMM 15.0N 84.1W 13.7N 87.5W 12.9N 91.1W 12.7N 93.3W

LBAR 20.7N 81.5W 24.6N 81.9W 28.0N 80.7W 30.9N 73.9W

SHIP 45KTS 59KTS 61KTS 60KTS

DSHP 35KTS 28KTS 30KTS 29KTS



...INITIAL CONDITIONS...

LATCUR = 17.1N LONCUR = 82.2W DIRCUR = 120DEG SPDCUR = 4KT

LATM12 = 17.8N LONM12 = 82.9W DIRM12 = 90DEG SPDM12 = 3KT

LATM24 = 17.4N LONM24 = 83.4W

WNDCUR = 30KT RMAXWD = 70NM WNDM12 = 30KT

CENPRS = 1008MB OUTPRS = 1012MB OUTRAD = 200NM SDEPTH = M

RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM



$$

NNNN
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Quoting Jeff9641:


I think the GFDL seems more realistic.
Slightly more realistic, but still a little over the top in my opinion. I'm not saying this won't be a major cane, but I don't see it becoming a hurricane in 24 hours. Although Paula did catch us by surprise, she was a very small storm, as a result able to intensify quickly.
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Quoting Jeff9641:


If they name this tomorrow then by then FL will be in the 5 day cone for sure. I'm thinking Cedar Key to Naples.


5 1/4 days from now. 12Z GFDL

Member Since: 30 janvier 2010 Posts: 0 Comments: 3259
Quoting reedzone:
The GFDL makes alot more sense on this run, course it is the 12Z run, a better, amplified run. A major slamming into Mexico, then catches a trough in the GOM, moves NE. Very umm, Wilma like. It's a possible scenario. Not buying the HWRF yet, too far north. I believe that conditions will get favorable as predicted and this may surprise lots of umm downcasters in here ;)

*This is my personal opinion, don't hate*

Reed: Don't woory about the dowmcasting Reed haters. You are my Favorite Wishcaster. That is a complament.

Do you think it will go into FL?
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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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