Little change to 99L, which remains very close to tropical depression status

By: Dr. Jeff Masters , 7:11 PM GMT on October 20, 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 AEKDB1990:



Or little Richard singing tutti-fruity.


Good Golly Miss Molley! Someone who remembers Little Richard. I remember him singing that song.
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this is going straight to hurricane at 2am advisory, see a little white spec forming..jmo

Link
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774. HadesGodWyvern (Mod)
Japan Meteorological Agency
Tropical Cyclone Advisory #8
TROPICAL DEPRESSION 18
12:00 PM JST October 21 2010
=================================

SUBJECT: Tropical Depression Near The Marianas

At 3:00 AM UTC, Tropical Depression (1004 hPa) located at 17.0N 142.7E has 10 minute sustained winds of 30 knots with gusts of 45 knots. The depression is reported as moving west northwest at 13 knots

Dvorak Intensity:

Forecast and Intensity
=======================
24 HRS: 16.3N 138.7E - 35 knots (CAT 1/Tropical Storm)
Member Since: Posts: Comments:
UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 21 OCT 2010 Time : 031500 UTC
Lat : 17:29:23 N Lon : 81:05:21 W


CI# /Pressure/ Vmax
2.1 /1008.2mb/ 31.0kt


Final T# Adj T# Raw T#
2.1 2.2 2.7

Latitude bias adjustment to MSLP : +0.0mb

Center Temp : -5.4C Cloud Region Temp : -28.4C

Scene Type : CURVED BAND with 0.42 ARC in LT GRAY
Maximum CURVED BAND with 0.44 ARC in LT GRAY
at Lat: 16:28:47 N Lon: 81:04:48 W

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : ATLANTIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : 0.2T/hour
Weakening Flag : OFF
Rapid Dissipation Flag : OFF

****************************************************
Member Since: July 15, 2006 Posts: 170 Comments: 53487
latest statistical and dynamic models.



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19L/TD/XX
MARK
17.63N/81.34W
Member Since: July 15, 2006 Posts: 170 Comments: 53487
Quoting Grothar:


Certainly is, I leave for a quick nap and wake up to another depression. Looks awfully good. Think it might be stronger than they originally thought??


Yes. I think it will be much stronger than what the NHC thinks it will be. As for the track, it will probably change to.
Member Since: October 8, 2008 Posts: 14 Comments: 4553
The only time we should get worried about this system is if we see this.

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Quoting 954FtLCane:

I forgot to list that my Sarcasm flag was on.


Yo! 954! It is when you aren't sarcastic we get worried. Keeps people on their toes, right Cosmic??
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Quoting caneswatch:


He's looking good, Hawk.


Certainly is, I leave for a quick nap and wake up to another depression. Looks awfully good. Think it might be stronger than they originally thought??
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Wish you could see this

Link
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Quoting Grothar:


He's looking good, Hawk.
Member Since: October 8, 2008 Posts: 14 Comments: 4553
Quoting Seastep:
How are thing Gro?

Don't they have a curfew at those places? ;)


Sneaked out during metamucil break, Thanks for asking. How you doing Sea? Think we will see TD19. LOL
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Quoting TropicalMan2010:

no just tiny very cold cloudtop passed the blues

I forgot to list that my Sarcasm flag was on.
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Member Since: July 15, 2006 Posts: 170 Comments: 53487
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Invest 99L
19Oct 06amGMT - 16.0n83.1w - 25knots- 1009mb - ATCF*15.7n83.0w*1008mb*15.8n82.9w
19Oct 12pmGMT - 16.7n83.3w - 25knots(46.3km/h) - 1009mb - *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 - 1008mb - ATCF*1007mb
20Oct 06pmGMT - 17.6n81.6w - 30knots - 1008mb - ATCF*17.1n82.2w
TropicalDepression19
21Oct 12amGMT - 17.6n81.2w - 30knots(~55.6km/h) - 1006mb - ATCF
21Oct 12amGMT - 17.5n81.1w - 35mph(~56.3km/h) - - 1006mb - NHC.Adv.#1
* Before NHC reevaluated&revised the ATCF numbers
25knots=(46.3km/h) _ 30knots=(~55.6km/h)

Copy&paste 16.0n83.1w, 16.7n83.3w, 17.4n83.4w, 17.7n83.2w, 17.8n82.9w-17.7n82.5w, 17.7n82.5w-17.6n81.6w, 17.6n81.6w-17.6n81.2w, 17.6n81.2w-17.5n81.1w, rtb, puz, nbw into the GreatCircleMapper for a look at the last 21^hours

^ The easternmost line-segment spans 3hours between the last two reported positions
Each of the preceeding 3 line-segments spans 6hours between reported positions.
Member Since: August 21, 2007 Posts: 0 Comments: 4860
How are thing Gro?

Don't they have a curfew at those places? ;)
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WTNT01 KNGU 210301
WARNING ATCN MIL 19L NAT 101021024622

2010102100 19L NINETEEN 001 01 100 02 SATL 050
T000 176N 0812W 030
T012 171N 0807W 030
T024 168N 0807W 030
T036 164N 0811W 035 R034 040 NE QD 030 SE QD 020 SW QD 040 NW QD
T048 163N 0817W 040 R034 050 NE QD 040 SE QD 030 SW QD 050 NW QD
T072 166N 0841W 050 R050 040 NE QD 030 SE QD 020 SW QD 040 NW QD R034 070 NE QD 050 SE QD 040 SW QD 060 NW QD
T096 180N 0875W 055
T120 195N 0900W 030
AMP
NNNN
REF/A/NAVLANTMETOCCEN NORFOLK VA/212000Z OCT 10//
AMPN/TROPICAL CYCLONE FORMATION ALERT//
SUBJ: TROPICAL DEPRESSION NINETEEN (19L) WARNING NR 001
1. TROPICAL DEPRESSION NINETEEN (19L) WARNING NR 001
01 ACTIVE TROPICAL CYCLONE IN ATLANTIC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
210000Z --- NEAR 17.6N 81.2W
MOVEMENT PAST SIX HOURS - 100 DEGREES AT 02 KTS
POSITION ACCURATE TO WITHIN 050 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
REPEAT POSIT: 17.6N 81.2W
---
FORECASTS:
12 HRS, VALID AT:
211200Z --- 17.1N 80.7W
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
VECTOR TO 24 HR POSIT: 180 DEG/ 02 KTS
---
24 HRS, VALID AT:
220000Z --- 16.8N 80.7W
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
VECTOR TO 36 HR POSIT: 225 DEG/ 03 KTS
---
36 HRS, VALID AT:
221200Z --- 16.4N 81.1W
MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT
030 NM SOUTHEAST QUADRANT
020 NM SOUTHWEST QUADRANT
040 NM NORTHWEST QUADRANT
VECTOR TO 48 HR POSIT: 260 DEG/ 03 KTS
---
EXTENDED OUTLOOK:
48 HRS, VALID AT:
230000Z --- 16.3N 81.7W
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
040 NM SOUTHEAST QUADRANT
030 NM SOUTHWEST QUADRANT
050 NM NORTHWEST QUADRANT
VECTOR TO 72 HR POSIT: 280 DEG/ 06 KTS
---
72 HRS, VALID AT:
240000Z --- 16.6N 84.1W
MAX SUSTAINED WINDS - 050 KT, GUSTS 060 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT
030 NM SOUTHEAST QUADRANT
020 NM SOUTHWEST QUADRANT
040 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 070 NM NORTHEAST QUADRANT
050 NM SOUTHEAST QUADRANT
040 NM SOUTHWEST QUADRANT
060 NM NORTHWEST QUADRANT
VECTOR TO 96 HR POSIT: 295 DEG/ 09 KTS
---
LONG RANGE OUTLOOK:
NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 200 NM
ON DAY 4 AND 250 NM ON DAY 5... AND FOR INTENSITY
NEAR 20 KT EACH DAY.
---
96 HRS, VALID AT:
250000Z --- 18.0N 87.5W
MAX SUSTAINED WINDS - 055 KT, GUSTS 065 KT
WIND RADII VALID OVER OPEN WATER ONLY
VECTOR TO 120 HR POSIT: 305 DEG/ 07 KTS
---
120 HRS, VALID AT:
260000Z --- 19.5N 90.0W
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
---
REMARKS:
210300Z POSITION NEAR 17.5N 81.1W OR APPROX 381NM ESE OF COZUMEL,
MEXICO. 12FT SEAS: NONE. THIS WARNING SUPERSEDES AND CANCELS REF
A, NAVLANTMETOCCEN 212000Z OCT 10 TROPICAL CYCLONE FORMATION
212102Z AND 220301Z.//
BT
#0001
NNNN
1910101606 108N 751W 20
1910101612 109N 757W 20
1910101618 110N 763W 20
1910101700 113N 774W 20
1910101706 117N 784W 20
1910101712 123N 795W 20
1910101718 128N 804W 20
1910101800 133N 810W 20
1910101806 137N 814W 20
1910101812 141N 818W 25
1910101818 146N 823W 25
1910101900 153N 828W 25
1910101906 160N 831W 25
1910101912 167N 833W 25
1910101918 174N 834W 30
1910102000 177N 832W 30
1910102006 178N 829W 30
1910102012 177N 825W 30
1910102018 176N 816W 30
1910102100 176N 812W 30

Member Since: July 15, 2006 Posts: 170 Comments: 53487
210306Z OCT 10
FM NAVMARFCSTCEN
BT
UNCLAS
MSGID/NMFC/OVLY2/0087/OCT
OVLY/ATL STORM 19L/210000Z3/OCT/1OF1/TROP DEPRESSION 19L(NINETEEN)/METOC
TEXT/12//G/173600N7/0811200W2/D
TEXT/12//G/164800N9/0804200W4/D
TEXT/12//G/161800N6/0814200W5/S
TEXT/12//G/163600N6/0840600W8/S
TEXT/12//G/180000N9/0873000W8/S
TEXT/12//G/193000N3/0900000W9/D
LINE/6//G/173600N7/0811200W2/164800N9/0804200W4/161800N6/0814200W5
/163600N6/0840600W8/180000N9/0873000W8/193000N3/0900000W9
ARC/0/G///161800N6/0814200W5/050NM/050NM
ARC/0/G///163600N6/0840600W8/070NM/070NM
TEXT/12//G/153600N5/0784200W1/TROP DEPRESSION NINETEEN
TEXT/12//G/143600N4/0784200W1/21 OCT 0000Z
TEXT/12//G/133600N3/0784200W1/MAX 30 KT
TEXT/12//G/123600N2/0784200W1/100 AT 02 KT
TEXT/12//G/113600N1/0784200W1/34 KT RADII SHOWN
TEXT/12//G/183600N8/0764200W9/2200Z MAX 30
TEXT/12//G/193600N9/0774200W0/2300Z MAX 40
TEXT/12//G/203600N1/0800600W4/2400Z MAX 50
TEXT/12//G/213600N2/0833000W4/2500Z MAX 55
TEXT/12//G/223600N3/0860000W4/2600Z MAX 30
ENDAT
BT
#0001
NNNN

Member Since: July 15, 2006 Posts: 170 Comments: 53487
Quoting CosmicEvents:
Word is that he got the boot, so to speak.


That's low!!! LOL
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Quoting sunlinepr:
Interesting analysis from Levi32

As far as intensity goes, gradual organization will likely continue over the next couple days, but nothing too serious. However, steady intensification will likely set in if the system gets any kind of a convective core over the center, and at that point we would have the potential for another potent hurricane developing. Remember Paula developed in the face of worse dry air, and the pattern evolution over the next few days will be such that 99L will have to deal with less and less of it as time goes on.


We already have that. :)
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750. BtnTx
Quoting Seastep:


Search engines are quite useful in these situations.
Thanks!
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Quoting BtnTx:
Whatever happened to StormW ? Or is everyone still here too new to even know who he was?
Word is that he got the boot, so to speak.
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Regarding Dry Air - Interesting analysis from Levi32:

Quoting -

As far as intensity goes, gradual organization will likely continue over the next couple days, but nothing too serious. However, steady intensification will likely set in if the system gets any kind of a convective core over the center, and at that point we would have the potential for another potent hurricane developing. Remember Paula developed in the face of worse dry air, and the pattern evolution over the next few days will be such that 99L will have to deal with less and less of it as time goes on.
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Quoting 954FtLCane:


Look closely at 17 & 80, is that a pinhole eye I see?... hmmmmm


No... but very cold cloud top.
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Quoting BtnTx:
So StormW left the planet?


Search engines are quite useful in these situations.
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Look closely at 17 & 80, is that a pinhole eye I see?... hmmmmm
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743. BtnTx
Quoting sdswwwe:


Banned...
So StormW left the planet?
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Quoting bappit:
TD 19 has an awful lot of dry air near it. I would be surprised to see a strong storm develop from it regardless of the path it takes.

Sunlinepr's post shows the dry air encroaching. Interesting to watch the convection blowing up. I'm not sure it has time to wait for the shear to relax before the dry air conquers all.


The dry air point is valid in general, but TD19 has zero issue with shear, atm.
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TD 19 has an awful lot of dry air near it. I would be surprised to see a strong storm develop from it regardless of the path it takes.

Sunlinepr's post shows the dry air encroaching. Interesting to watch the convection blowing up. I'm not sure it has time to wait for the shear to relax before the dry air conquers all.
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Quoting BtnTx:
Whatever happened to StormW ? Or is everyone still here too new to even know who he was?


Banned...
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739. BtnTx
Whatever happened to StormW ? Or is everyone still here too new to even know who he was?
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738. JLPR2


GFS develops something in the Eastern Caribbean, but it's not the CATL low.
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Quoting shikori:


I think so


must be the lime in the coconut..

http://www.youtube.com/watch?v=aA9OqUuA6a0&feature=related

grin

referring to the white in the lime...uh..and i will learn to put a link in after puberty...doh
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Quoting AEKDB1990:
Megi's eye looked like it was 80 miles across, although seems to be contracting a bit 954FtLCane.

Yes about 80 miles and shrinking. Good thing it missed Hong Kong but I;m sure not good for the ones that look like they'll get hit by a strengthening Megi/Juan.
For others (it looks like you already have used it) Here's a great link I found on how to figure out how wide across the eye is or how far it is one lon/lat to another.
Link
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Stuck between 2 dry air masses.....

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Quoting AEKDB1990:
The Tampa Bay 1921 hurricane has been downgraded to Cat 2 on Wikipedia. But it is still Cat 3 on HURDAT. Link

I knew that couldn't be right, scratching my head on how it said, "slowly weakened making lanfall as a strong cat. 2 hurricane."
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TY, too, CV.

Close enough for me. Very high cloud tops.
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Quoting Seastep:
There is white in that lime, no?

Little help, please. Color-blind.

Larger image




Faint speck but, yes.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
TY
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There is white in that lime, no?

Little help, please. Color-blind.

Larger image


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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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