99L a threat to develop; damage from Typhoon Megi still largely unknown

By: Dr. Jeff Masters , 1:38 PM GMT on October 19, 2010

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Heavy thunderstorm activity has increased and grown more organized this morning over the southwestern Caribbean between Honduras and the Cayman Islands, in association with a tropical disturbance (Invest 99L). The storm is bringing heavy rain to the Cayman Islands; two inches has fallen so far this morning at Savannah on Grand Cayman Island. Recent satellite imagery shows that 99L has some rotation, and the winds on the northeast coast of Honduras at Puerto Lempira have shifted to the west-northwest, implying that 99L may be developing a surface circulation. Wind shear is a moderate 10 - 20 knots, which is low enough to allow some slow development. Water vapor satellite loops reveal that the atmosphere in the Western Caribbean is moist enough to support development, and the waters beneath are plenty warm, at 29°C. The latest SHIPS model forecast predicts that wind shear over the Western Caribbean will mostly remain in the moderate range, 10 - 20 knots, for the remainder of the week. The current north-northwest motion of 99L should continue until Wednesday, when a strong ridge of high pressure is forecast to build in, forcing 99L to the south or west. However, steering currents will be weak Wednesday through Friday, making it difficult to predict where 99L may wander to. The only models that develop 99L are the GFDL and HWRF. The GFDL model predicts that 99L will spend enough time over water to develop into a hurricane, and brings the storm to the coast of Mexico's Yucatan Peninsula on Sunday morning. The HWRF model has 99L making landfall over Honduras late this week, before the storm has a chance to develop into a hurricane. NHC is giving 99L a 40% chance of developing into a tropical depression by Thursday. I believe the odds are higher, near 60%. The Hurricane Hunters are on call to investigate 99L this afternoon.


Figure 1. Morning satellite image of Invest 99L.

Damage from Super Typhoon Megi still largely unknown
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 extent of the destruction wrought by the great storm is still largely unknown. Preliminary news reports indicate that at least 10 people died, and the northern Philippine province of Isabela suffered severe damage. 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. Baguio near the west coast of northern Luzon received 7.72" of rain from the storm, and many mountainous regions likely received over a foot of rain.


Figure 2. Rainfall rates in excess of 1 inch per hour (orange colors) were observed by the polar-orbiting F-18 satellite in association with Megi at 00:40 UTC October 19, 2010. Image credit: Navy Research Lab, Monterey.

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 built a formidable new eyewall. At the same time, 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 intensify into a very dangerous Category 4 storm by Thursday. 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 near 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.

"Daily Downpour" airing this afternoon
Our live Internet radio show, "Daily Downpour", will be airing today at 4pm EDT. The call in number is 415-983-2634, or you can post a question to broadcast@wunderground.com. You can tune in at http://www.wunderground.com/wxradio/wubroadcast.h tml, and I'll be discussing the latest info on Invest 99L with hosts Shaun Tanner and Tim Roche.

Jeff Masters

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You are correct sir, we have a TD.....congrats all (its like a birth)

Quoting CyclonicVoyage:
Vortex message says TD19 has formed.
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Quoting smartinwx:


I was going to say panama canal, but that's west of the canal.

It looks like someone used a 2000 flushes blue on the southern mexico coast

That's the upwelling caused by a recent Tehuano Event, a wind phenomenon (the Tehuantepecer) that can drop SSTs in the area by up to 10.C in a single day...

Click for larger image:

Appropriate tropical weather-related image
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Quoting Seastep:
Pressure falling rapidly at 42057. Pressure sub-1010 and should drop again at 4pm.

Winds consistently over 20kts for five hours now.


You must be prescient !. I was just about to post the data from that buoy. 99L starting to take on a different look now, more aggressive if I might put it that way.
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Nevermind, you have the vortex message already....hmmm, I am not seeing it on GE


Quoting Goldenblack:
CV, looks like the HH have zeroed in on about 17.3 to 17.4 N and 83.4 W or so...that is just right now.


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just tried restarting the browser..no effect...all other websites...no problem...just this website is doing it...i am using firefox...never had a problem before...i mean years...
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Vortex message says TD19 has formed.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
CV, looks like the HH have zeroed in on about 17.3 to 17.4 N and 83.4 W or so...that is just right now.


Quoting CyclonicVoyage:
Looking at data I believe the low center is a little further N @ 17.6N 83.6W
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Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 19th day of the month at 19:14Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 303)
Mission Purpose: Investigate eight suspect area (flight in the North Atlantic basin)
Mission Number: 1
Observation Number: 13
A. Time of Center Fix: 19th day of the month at 19:09:00Z
B. Center Fix Coordinates: 17°23'N 83°29'W (17.3833N 83.4833W)
B. Center Fix Location: 191 miles (308 km) to the SW (226°) from George Town, Cayman Islands (GBR).
C. Minimum Height at Standard Level: Not Available
D. Estimated (by SFMR or visually) Maximum Surface Wind: 27kts (~ 31.1mph)
E. Location of the Estimated Maximum Surface Wind: 20 nautical miles (23 statute miles) to the NNW (347°) of center fix
F. Maximum Flight Level Wind Inbound: From 112° at 20kts (From the ESE at ~ 23.0mph)
G. Location of Maximum Flight Level Wind Inbound: 21 nautical miles (24 statute miles) to the NNW (347°) of center fix
H. Minimum Sea Level Pressure: 1009mb (29.80 inHg) - Extrapolated
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 22°C (72°F) at a pressure alt. of 303m (994ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 23°C (73°F) at a pressure alt. of 302m (991ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 22°C (72°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Not Available
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Wind and Pressure
N. Fix Level: 1,500 feet
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 5 nautical miles
Remarks Section:
Maximum Flight Level Wind: 20kts (~ 23.0mph) in the north quadrant at 18:59:30Z
Sea Level Pressure Extrapolation From: Below 1,500 feet
Member Since: January 30, 2010 Posts: 0 Comments: 3259
Just in for a second....hi all.

Looking at Google Earth reconnaissance, seems there is a pretty good wind shift and closed circulation..
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Pressure falling rapidly at 42057. Pressure sub-1010 and should drop again at 4pm.

Winds consistently over 20kts for five hours now.
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Looking at data I believe the low center is a little further N @ 17.6N 83.6W
Member Since: January 30, 2010 Posts: 0 Comments: 3259
Quoting jiminceiba:
hi, can anyone tell me why my wunderground pages have gone from normal graphics...to simple html text?

i can't seem to figure this out...all of a sudden...i have this clunky display with just plain text....
Have you tried restarting your browser?
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Quoting Hurricanes101:


well then you are responding to the wrong person actually, I said that you saying it aint going to happen is just as ignorant as those who say a Major is coming to the US

read all of what I have to say before you comment, your part about the crying wolf and having people run for the exit was actually agreeing with what I said earlier


And yet look who rears his head defending him.

Odd huh? Not really.
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hi, can anyone tell me why my wunderground pages have gone from normal graphics...to simple html text?

i can't seem to figure this out...all of a sudden...i have this clunky display with just plain text....
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I Stick. bywhat i said this morning,td after recons in...
Quoting stillwaiting:
im willing to be the hh find a td when they go out,sooooo ......td looks probable sometime today imo......w/the stationary front dissipating,if it drifts far enough north h.into.te gom could be a threater to fl....
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Quoting stormpetrol:

WE have a closed surface circulation from the data I've seen and winds to support a 35 mph TD, if they stay in another hour or 2 , by time they leave we may have TS Richard at 5pm EST, JMO.


I'm with you. It seems like it has reached it's intensity minimum and is building convection again.

Currently stationary and happy.
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Quoting Neapolitan:
ATCF says winds are up to 30 knots, while pressure is still 1009mb. 17.0N / 83.0W

AL, 99, 2010101918, , BEST, 0, 170N, 830W, 30, 1009, LO, 34, NEQ, 0, 0, 0, 0, 1012, 250, 50, 0, 0, L, 0, , 0, 0, INVEST, S


nope
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Quoting WeatherLoverinMiami:
TROLL ALERT CONDITION Red THE GUY JUST GOT THE ACCOUNT AND ALREADY TALKING TRASH


Same goes for FLstormwarning, flag him as well.
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Quoting utilaeastwind:


Circulation is closing and HH data supports TD strength winds at mentioned location. Also, the wind direction points to a COC.



agree.

A little convection this evening and we could see a TD tomorrow morning.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
Quoting tropicfreak:


Not until we have a closed surface circulation.

WE have a closed surface circulation from the data I've seen and winds to support a 35 mph TD, if they stay in another hour or 2 , by time they leave we may have TS Richard at 5pm EST, JMO.
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1009.7 mb
(~ 29.82 inHg)
Member Since: January 30, 2010 Posts: 0 Comments: 3259
Quoting pioggiasuper:


lol going C. I thought you said this was Richard already? In that case, you should have picked F. None of the above.
TROLL ALERT CONDITION Red THE GUY JUST GOT THE ACCOUNT AND ALREADY TALKING TRASH
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ATCF says winds are up to 30 knots, while pressure is still 1009mb. 17.0N / 83.0W

AL, 99, 2010101918, , BEST, 0, 170N, 830W, 30, 1009, LO, 34, NEQ, 0, 0, 0, 0, 1012, 250, 50, 0, 0, L, 0, , 0, 0, INVEST, S
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18:49:30Z 17.233N 83.483W 977.0 mb
(~ 28.85 inHg) 289 meters
(~ 948 feet) 1009.8 mb
(~ 29.82 inHg) - From 262° at 6 knots
(From the W at ~ 6.9 mph) 22.9°C
(~ 73.2°F) 22.7°C
(~ 72.9°F) 7 knots
(~ 8.0 mph) 22 knots
(~ 25.3 mph)
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Quoting tropicfreak:


Not until we have a closed surface circulation.


Circulation is closing and HH data supports TD strength winds at mentioned location. Also, the wind direction points to a COC.

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Quoting pilotguy1:


You know, what is really wrong with this blog is the experts (so called). This storm hasn't even formed yet and a bunch of you have people running for the exits. If you go on any serious forecasting site they aren't even talking about this thing forming into a tropical storm of any significance. If that happens I believe we should sound the alarm, but at this point it is way early to start calling for half the stuff I have read today. Even if we think the thing develops into something there is plenty of time for people to prepare. Have half of you ever heard of the little boy that cried wolf or chicken little?


well then you are responding to the wrong person actually, I said that you saying it aint going to happen is just as ignorant as those who say a Major is coming to the US

read all of what I have to say before you comment, your part about the crying wolf and having people run for the exit was actually agreeing with what I said earlier
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Quoting IKE:


Good luck convincing some, of what you said.

Props for trying.



Look who has come out to play. Another downcaster lmao. Go back to your caves
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Quoting Hurricanes101:


Spoken like someone who is not around when we have activity

To say anything is not going to happen before the storm has even formed shows just as much ignorance as those who claim this will hit Florida as a Major

This storm still has a ways to go for development and the idea is that it will stay down in the Caribbean for a few days. Be patient, sit back, relax and have a drink.


Spoken like one who's smart.
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294. IKE
Quoting pilotguy1:


You know, what is really wrong with this blog is the experts (so called). This storm hasn't even formed yet and a bunch of you have people running for the exits. If you go on any serious forecasting site they aren't even talking about this thing forming into a tropical storm of any significance. If that happens I believe we should sound the alarm, but at this point it is way early to start calling for half the stuff I have read today. Even if we think the thing develops into something there is plenty of time for people to prepare. Have half of you ever heard of the little boy that cried wolf or chicken little?


Good luck convincing some, of what you said.

Props for trying.
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Quoting Hurricanes101:


Spoken like someone who is not around when we have activity

To say anything is not going to happen before the storm has even formed shows just as much ignorance as those who claim this will hit Florida as a Major

This storm still has a ways to go for development and the idea is that it will stay down in the Caribbean for a few days. Be patient, sit back, relax and have a drink.


Love to, but still at work...
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Quoting utilaeastwind:



Looks like we have a tropical depression at 17.5N 83.5W


Not until we have a closed surface circulation.
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Appears to be alot of contaminated data, anyway I see enough data to support a 30-35mph TD.
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Looks like we have a tropical depression at 17.5N 83.5W
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Quoting oracle28:


Question: Does anyone know what that area of cold(er) water south of Mexico is? Is it runoff from (Matthew?) any ideas?


I was going to say panama canal, but that's west of the canal.

It looks like someone used a 2000 flushes blue on the southern mexico coast
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Getting in that eastern quad now. A little more impressive

18:38:30Z 17.417N 83.367W 977.6 mb
(~ 28.87 inHg) 285 meters
(~ 935 feet) 1010.3 mb
(~ 29.83 inHg)

SFMR
33 knots
(~ 37.9 mph)
Member Since: January 30, 2010 Posts: 0 Comments: 3259
Product: Air Force Tropical RECCO Message (URNT11 KNHC)
Transmitted: 19th day of the month at 18:44Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 303)
Mission Purpose: Investigate eight suspect area (flight in the North Atlantic basin)
Mission Number: 1
Observation Number: 11

Mandatory Data...

Observation Time: Tuesday, 18:42Z
Radar Capability: Yes
Aircraft Altitude: Below 10,000 meters
Coordinates: 17.2N 83.4W
Location: 197 miles (316 km) to the SW (222°) from George Town, Cayman Islands (GBR).
Turbulence: None
Conditions Along Flight Route: In the clear
Pressure Altitude: 310 meters
Flight Level Wind: From 240° at 10 knots (From the WSW at ~ 11.5 mph)
- The above is a spot wind.
- Winds were obtained using doppler radar or inertial systems.
Flight Level Temperature: 23°C
Flight Level Dew Point: 22°C
Weather (within 30 nautical miles): Clear
Mean Sea Level Pressure (MSLP): 1010 mb (extrapolated)

Optional Data...

Estimated Surface Wind: From 220° at 15 knots (From the SW at ~ 17.2 mph)

Remarks Section...

Surface Wind Speed (likely by SFMR): 17 knots (~ 19.6mph)
Member Since: January 30, 2010 Posts: 0 Comments: 3259
After it moves through FL, do any of y'all think that it could ride up the east coast?
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The latest 12Z shear forecast shows the majority of the GOM in high shear through 168hrs. For 99L to be anything significant for the CONUS it's going to have to stall out in the Caribbean for a long time and hit that window perfectly. Chances are that won't happen. Link
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Quoting pilotguy1:


It ain't gonna happen. Cool your jets folks.


Spoken like someone who is not around when we have activity

To say anything is not going to happen before the storm has even formed shows just as much ignorance as those who claim this will hit Florida as a Major

This storm still has a ways to go for development and the idea is that it will stay down in the Caribbean for a few days. Be patient, sit back, relax and have a drink.
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Weather this storm forms or not, looks like it's gonna be a chilly Halloween for many in the East in the wake of that trough!

But before that, a short fused warm spike will precede the trough(which'll be an Appellations Cutter
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Quoting FLstormwarning:
OMG! What in the world! This looks like a nightmare scenario for FL. FL better get ready this pans out!

http://www.coaps.fsu.edu/~maue/extreme/gfdl/invest99l.2010101912_nest3.png
even then a hard right hook is possible for a miss
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Quoting tropicfreak:


But be on guard and watch 99L very closely.


Thank you I will. Charley and Wilma are still very fresh in my mind.
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To sum it up. Looks like we have a broad area of low pressure still.

1010mb peak winds 29mph so far.

However, I did find this kind of interesting, especially the location.

18:00:00Z 18.767N 84.617W 565.2 mb
(~ 16.69 inHg) 4,882 meters
(~ 16,017 feet) 1007.7 mb
(~ 29.76 inHg)
Member Since: January 30, 2010 Posts: 0 Comments: 3259
Quoting Levi32:
Good morning all.

Tropical Tidbit for Tuesday, October 19th, with Video


Video Link
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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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