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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Quoting Bordonaro:

Yes, there will be an upward MJO over the next 5-10 days.

You think it will still be around in 5-10 days?
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Quoting TropicalAnalystwx13:
We should have a Tropical Depression tomorrow...Dry Air getting at it right now.

However, we saw what Paula did in conditions like this...I believe we may be dealing with a potentially dangerous storm in the days ahead.



What's your opinion; with this scenario, will it be able to cross that DA / shear and enter the Gom???
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Quoting pottery:

But you think the dry air is going to go away?

Yes, there will be an upward MJO over the next 5-10 days.
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921. HadesGodWyvern (Mod)
Japan Meteorological Agency
Tropical Disturbance Summary
TROPICAL DEPRESSION XX
9:00 AM JST October 20 2010
============================

At 0:00 AM UTC, Tropical Depression (1006 hPa) located at 16.0N 148.0E has 10 minute sustained winds of 25 knots with gusts of 40 knots. The depression is reported as moving west at 10 knots
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Quoting TropicalAnalystwx13:


Pfft...Heck if I know. :)

But you think the dry air is going to go away?
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Quoting pottery:

Where do you think it will end up going?


Pfft...Heck if I know. :)
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Quoting TropicalAnalystwx13:
We should have a Tropical Depression tomorrow...Dry Air getting at it right now.

However, we saw what Paula did in conditions like this...I believe we may be dealing with a potentially dangerous storm in the days ahead.

Where do you think it will end up going?
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We should have a Tropical Depression tomorrow...Dry Air getting at it right now.

However, we saw what Paula did in conditions like this...I believe we may be dealing with a potentially dangerous storm in the days ahead.
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That's interesting, Sunline..
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Interesting area

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Quoting kmanislander:


There is no anomaly with the reading I just gave. It is real time from a calibrated station on which I installed a new anemometer only two weeks ago.

The Island could be experiencing some isolated down-drafts, which could account for gusts to 17-19 mph fanning out ?
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Interesting S or 5 cloud area at 15N 40W

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Quoting pottery:
Yeah, I realise that.
I thought it was funny though, all those conflicting wind directions.


A clear case of wheat and chaff my friend.
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Quoting kmanislander:


The problem with a reporting station is that you get a snap shot reading when it updates. A few seconds later the wind direction may shift to the true reading. At least I am watching my station with the heading moving back and forth between NE and East in real time.
Yeah, I realise that.
I thought it was funny though, all those conflicting wind directions.
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Slow day but, should pick up later tonight and the following days as richard goes on.
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Quoting shikori:
The readings we gave just now are anomalous and mine is the most anomalous cming out of EE


There is no anomaly with the reading I just gave. It is real time from a calibrated station on which I installed a new anemometer only two weeks ago.
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Quoting pottery:

But ESE at the airport?
You all are in the thick of things.
Hope you manage OK..

heheheh


The problem with a reporting station is that you get a snap shot reading when it updates. A few seconds later the wind direction may shift to the true reading. At least I am watching my station with the heading moving back and forth between NE and East in real time.
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I can't belive that if this developes we'll have our 17th named storm and 19th depression.And remember we still have some weeks to go before the season is over.And who knows maybe december could pull a slick one on us.Like 2007.
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Quoting lightningbolt73:
I sure wish we were going to get some rain from 99 l. We sure could use it here in Sarasota Florida


We are receiving our first light rain since Aug.24 here in SCentral Ms. Hopefully this will come your way. We are excited over just this small amount..lol..
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Quoting pottery:

But ESE at the airport?
You all are in the thick of things.
Hope you manage OK..

heheheh


LOL. Hardly a breath of air outside right now
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Hi Megi, my post 1000 is dedicated to you..... how about some Merlot??

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Quoting shikori:
Someone needs to contact the P.O. in EastEnd then
Why ?
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Have to remove as an absolutely horrible and misleading post.
Member Since: September 9, 2008 Posts: 6 Comments: 3414
Quoting lightningbolt73:
Let me try this again! I'm a new user and I tried to post a coment and it didn't go through
That happens sometimes but I don't know why. I have been trying for hours to post the Navy's TCFA and it won't post for some reason.
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Quoting KerryInNOLA:
Yes, the CONUS is part of what is loosely called "solid land". There were no "solid" land Hits this year.


U make no since
Member Since: June 2, 2010 Posts: 0 Comments: 1343
Quoting kmanislander:
Winds variable between 5 and 7 mph at my home on the SW side between East and NE

No NNW winds here as far as I can determine.

But ESE at the airport?
You all are in the thick of things.
Hope you manage OK..

heheheh
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Quoting shikori:
Wow its now saying NNW at 19 mph 1010mb


Maybe a bird is sitting on the weather vane LOL
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Winds variable between 5 and 7 mph at my home on the SW side between East and NE

No NNW winds here as far as I can determine.
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Let me try this again! I'm a new user and I tried to post a coment and it didn't go through
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Quoting shikori:
East End

Well, based on those wind directions from you and Kman, the eye should be passing overhead very shortly LOL
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Quoting shikori:
I am in gt but i am using ee automatic weather station thingy
LinkUse this link. It gives you different areas in Cayman and Cayman Brac. Also NRL link and links to the buoys.
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Quoting stormwatcherCI:
Current 75.4 °F 5.8 6.9 ESE


yeah

Owen Roberts, GC (Airport)
Updated: 19 min 29 sec ago
77 °F
Light Rain
Humidity: 94%
Dew Point: 75 °F
Wind: 13 mph from the ESE
Pressure: 29.89 in (Steady)
Visibility: 6.2 miles
UV: 0 out of 16
Clouds: Few 1400 ft
Overcast 8000 ft
(Above Ground Level)

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Quoting kmanislander:


Strange. Here is the george Town Port which agrees with my station and showing NE
Current 75.4 °F 5.8 6.9 ESE
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883. JRRP
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Quoting kmanislander:


Strange. Here is the George Town Port which agrees with my station and showing NE


Oh, no data there since 8 am !!
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Quoting shikori:
East End

You are getting NNW winds right now?
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Quoting stormwatcherCI:
EE says NNW at 17 mph.


Strange. Here is the George Town Port which agrees with my station and showing NE
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Quoting shikori:
East End
Last night you told me GT.
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Quoting pottery:

?? where is Shikori?
I am confused..
In George Town.
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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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