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 CyclonicVoyage:


Because it's all speculation at this point and it's not even classified as a tropical entity yet.



Thanks - I guess they pick and choose which models to show us because these are not the ones I saw this morning.
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Quoting FLstormwarning:


Sorry I was out of line and lashed out. I am sorry for being an ASS and calling names. I really thought you were attacking me and I deeply apologize for my actions. I am sorry for being a "Dick".



No doubt I was needleing you a little. No harm done. Apology accepted.
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I have to say 99L is definitely taking the shape of a Tropical Depression. Still, I don't expect an upgrade until this afternoon.
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1267. scott39
If a ridge builds over FL. wouldnt this put the Gulf Coast at risk?
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Link
Crown Weather TWD for this morning. Very interesting synopsis.
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typhoonfury:
Raw footage I shot in HD of typhoon #Juan #Megi slamming Philippines as well as aftermath shots - http://youtu.be/R9tckfJrTnI
about 2 hours ago from TweetDeck


typhoonfury:
Back home safely in Hong Kong. In need of a massive meal & lot of rest. Chill out day tmrw before probably venturing into China for #Megi
about 3 hours ago from TweetDeck
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Quoting kitkat954:


OK - 3 tv stations in the Miami area this morning say NOTHING about this affecting Florida - according to all of them this is going to CA - They are all blowing it off as if its nothing for us to be concerned with. Am I missing something?


Because it's all speculation at this point and it's not even classified as a tropical entity yet.

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1263. 7544
looks like the may have to relocate the coc under the heavy conv. thats now forming and blowing up on the west side? so i would look for the plane to be doing that latter today its looking good now .
Member Since: May 6, 2007 Posts: 0 Comments: 6874
Invest 99L now:



Nicole as a Tropical Depression:



Nicole lacked the structure that 99L has, and 99L is lacking the convection Nicole had.
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Quoting Orcasystems:
Complete Update

A Cat 5... WTF



AOI
AOI AOI AOI

AOI AOI AOI

TS BUSTED FORECAST ALIBI

Wow. One of the predicted models is a WTF bomb.
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Quoting FLstormwarning:


He used Dick to say I don't know Dick and that was not cool. I said the samething JB said and he has the gall to tell me I know nothing. WELL!

Storm is that you?
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1254. ackee
99L SURE Looks better than nicole did when the NHC had upgraded it
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1252. pottery
Quoting afj3:

Cool. Thanks! I wish I had some links to educate me so I can comment intelligently in here...

Go to the main WU page, and spend some time looking through the links there.
Some are easily understood.
Also, check Poster LEVI's update in a while, right here.
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Quoting 7544:
hwrf agrees with the gfdl now and takes it est of the yucatan look at the end of the run looks like it tries to turn ne at that time sorta like wilma did so we have to wait for the new run latter today could that happen as the high moves east and the trof kicks in to push it ne ? also the clip model has been showing that track for days now and now it shows closer to so fla . tia


OK - 3 tv stations in the Miami area this morning say NOTHING about this affecting Florida - according to all of them this is going to CA - They are all blowing it off as if its nothing for us to be concerned with. Am I missing something?
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Now that was downright unfriendly!
Report mine if you like. It's a play on the name "Richard". And JB hasn't said Florida is safe. Neither have I. It's just not as nearly imminent as your immature self would obviously like it to be. Grow up and develope a little thicker layer of skin. It'll serve well here and everywhere else in the long run.
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Oh, where for art thou LEVI?
L -- Long-sufferingly
E -- Expecting
V -- Vortex
I -- Information
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Quoting islander101010:
i dont think recon is going to find a closed off low it needs to break off the mid level trough and become more circular in structure


They found one yesterday, and its strengthened since yesterday, so I would assume that there is a closed low still....That has strengthened.
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1242. afj3
Quoting pottery:

The satellite images show the TOP of the system being blown to the east, by wind-shear.
The main body of the storm is pretty stationary right now.

Cool. Thanks! I wish I had some links to educate me so I can comment intelligently in here...
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Quoting cat5hurricane:

I thought the was the same trough that was going to dip far enough down into the GOM to turn him NE though...?

Exactly again increase shear but he doesnt seem to understand that.
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i dont think recon is going to find a closed off low it needs to break off the mid level trough and become more circular in structure
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Quoting HaboobsRsweet:
Also if any of you look at the 72 hour forecast on NHC they still have it as a low 72 hours from now and not a TS.


They actually won't change that until it's actually classified as a tropical system. However, they indicate the possibility.

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1237. pottery
Quoting afj3:
Morning all!
Novice needs advice. Why do the models show 99L heading to Central America while the satellite has it racing eastward? Please help this novice out. Thanks!

The satellite images show the TOP of the system being blown to the east, by wind-shear.
The main body of the storm is pretty stationary right now.
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POLL TIME!

Q: When will 99L be designated a Tropical Depression?

A. This morning (11AM)
B. This afternoon (2PM, 5PM)
C. Tonight (8PM, 11PM, 2AM)
D. Tomorrow Morning (5AM, 8AM, 11AM)
E. OTHER/LATER

Q: When will Invest 99L become a Tropical Storm?

A. This morning (11AM)
B. This afternoon (2PM, 5PM)
C. Tonight (8PM, 11PM, 2AM)
D. Tomorrow Morning (5AM, 8AM, 11AM)
E. OTHER/LATER

*I highlighted my answers in bold*
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1234. IKE
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1233. afj3
Quoting HaboobsRsweet:
Also if any of you look at the 72 hour forecast on NHC they still have it as a low 72 hours from now and not a TS.

Gotta link??? Thanks!
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1232. 7544
gfdl 140 k wow CAT 5 ?

Link
Member Since: May 6, 2007 Posts: 0 Comments: 6874
1230. afj3
Morning all!
Novice needs advice. Why do the models show 99L heading to Central America while the satellite has it racing eastward? Please help this novice out. Thanks!
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Also if any of you look at the 72 hour forecast on NHC they still have it as a low 72 hours from now and not a TS.
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I believe this system will get designated later today as Shear begins to let up.

I then believe once strengthening a bit, it will undergo Rapid Intensification, becoming the season's 10th hurricane.

Not even forecasting for anything after that.
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1227. pottery
Quoting kmanislander:
I will be back once data from the HH starts coming in

OK.
But in the meantime, the forecasts for Grand Cayman dont look too bad for today and beyond.
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1226. ackee
when will 99L be upgraged TO TD or TS

A 5PM
B 11PM
C NEXT 24 HOURS
D NEXT 48 TO 72 HOURS
E remain an Invest
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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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