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

By: Dr. Jeff Masters , 19:11 GMT le 20 octobre 2010

Share this Blog
2
+

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

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 376 - 326

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24Blog Index

Quoting HurricaneDean07:

looks like td 19 on its way.
Poll Time:
Do you think 99L will be TD Nineteen at the
(A) 8 PM today
(B) 11 PM tonight
(C) 2 AM tomorrow morning
(D) 5 PM tomorrow morning
(E) Not until late tomorrow


B
Member Since: Posts: Comments:
Quoting Jeff9641:
Tampa Shield GONE!!

http://www.coaps.fsu.edu/~maue/extreme/hwrf/invest99l.2010102018_wind.png


That would make sense, if this were a month ago.
Member Since: Posts: Comments:
I missed the last couple of hours, are the hurricane hunters flying in tonight?
Member Since: Posts: Comments:
as of this time, Were saying good morning to Megi and g'nite to 99L.
Member Since: Posts: Comments:
Dinner time. Back later
Member Since: Posts: Comments:
Here is my post from earlier this afternoon

210. kmanislander 9:16 PM GMT on October 20, 2010
Quoting whadat:
Yep. gregmerren. This system is killing me - don't know whether to do all out prep with the big boat or just expect marginal TS winds. If it does get going I probably won't have anytime to do much.


Ah, that explains it it LOL

Run this loop and you will see the old center virtually disappear from view into the deep convection located at 17 N and 81 W. This strongly suggests that a center relocation is underway but I won't know for sure until I see another 4 frames or so load and run. Regardless, the steering will remain weak for the next couple of days so this is unlikely to come up on us quickly even if it develops.

From where it is now the more likely track is to the WNW but we are not out of the woods yet.
Hard to say whether to prep or not because this time of year they can go anywhere but all indications are for very slow motion at least through 24 hours.


Action: Quote | Modify Comment
Member Since: August 19, 2006 Posts: 0 Comments: 12172
Member Since: Posts: Comments:
Well, these dang ensembles are starting to look a bit more ominous. I posted last night that I was concerned about Texas, as I will be there next week. No one was very high on the likelihood of 99l approaching Texas; still may not, but these models are starting to get interesting.
Member Since: Posts: Comments:
Quoting stormwatcherCI:
.SPECIAL FEATURES...

AS OF 2100 UTC...A 1006 MB LOW IS CENTERED S OF THE CAYMAN
ISLANDS NEAR 17N81W.


Yep, that is the position I had it at from about 4 pm today
Member Since: Posts: Comments:
Quoting Saltydogbwi1:


Hey Kman looks like COC could be trying to organise around 81W17.5N what do you think?
.SPECIAL FEATURES...

AS OF 2100 UTC...A 1006 MB LOW IS CENTERED S OF THE CAYMAN
ISLANDS NEAR 17N81W.
Member Since: 9 octobre 2008 Posts: 0 Comments: 8323
And I keep saying...The time is wrong.And he keeps saying "Zulu, Zulu" Must be some Tarzan movie I don't recall
Member Since: Posts: Comments:
I'd be pretty darn surprised if we only get 17. Even though that would have ment my May 2010 prediction would
have pretty much nailed it, the waters are still very warm out there and it is probable we'll see at least 2 more after Richard, Shary and Tomas, to give us a grand total of 19..
Member Since: 8 juillet 2005 Posts: 259 Comments: 23882
Quoting Neapolitan:


If you're gonna do a proper poll, you have to allow for every possibility. (Hint: ranges work better than absolutes.) At any rate, my answer--as it was the other day--f) 0%

I have been trying to make my avatar like Neopolitans but my blond hair keeps getting in the way...My hubby keeps saying"You are a true blonde, Live with it
Member Since: Posts: Comments:
Quoting Jeff9641:
Tampa Shield GONE!!


We're gonna have ta try diverting tha warp engines Cap'n!
Member Since: Posts: Comments:
Quoting CosmicEvents:
I think they'll fly, but if they don't...it's good to have the ground OBS from you and others on GC. And, as always, your insight.


Thanks. Winds very calm here now ( 4 mph ) out of the ENE and NE which pretty much confirms a new center to the SE of Grand Cayman. I suspect that once the HH gets in that deep convection we are going to see TS force winds.
Member Since: Posts: Comments:
Quoting Saltydogbwi1:


Hey Kman looks like COC could be trying to organise around 81W17.5N what do you think?
......ding,ding,ding,...you are correct,apparent on rgb....
Member Since: Posts: Comments:
Quoting CybrTeddy:
Kinda contradicting to raise the odds and say 'has changed little in organization'


Well, not really; odds or for the next 48 hours, so the increase in odds mean they're recognizing that conditions for development will improve...
Member Since: 8 novembre 2009 Posts: 4 Comments: 13508
last hurricane possibly, last tropical storm definitely not

we will end this season with 19 named storms as i predicted earlier this year. http://www.wunderground.com/blog/Twinkster/show.html
Member Since: Posts: Comments:
Quoting Neapolitan:


If you're gonna do a proper poll, you have to allow for every possibility. (Hint: ranges work better than absolutes.) At any rate, my answer--as it was the other day--f) 0%
agreed
Member Since: Posts: Comments:
Quoting Surfcropper:
Percentage 99L is the last atlantic hurricane season event of 2010..

a) 100%

b) 60%

c) 30%

d) 10%

e) less than 10%


I say a) 100%


I say d) 10%.

Pretty darn unlikely that 99L will be our last named storm to me. Still plenty warm out there, and good conditions. La Nina years usually crank out a storm in November and December (2003, 2007, 1995, ect)
Member Since: 8 juillet 2005 Posts: 259 Comments: 23882
Quoting CybrTeddy:
Up to 80%.

Kinda contradicting to raise the odds and say 'has changed little in organization'

Think they noticed that the COC might be relocating.


Baby steps, but I am sure they have noticed, hence the language stating that a TD could form at any time tonight or tomorrow.
Member Since: Posts: Comments:
Quoting RyanFSU:
18Z HWRF doomcast


Link?
Member Since: Posts: Comments:
Quoting Surfcropper:
Percentage 99L is the last atlantic hurricane season event of 2010..

a) 100%

b) 60%

c) 30%

d) 10%

e) less than 10%


I say a) 100%


If you're gonna do a proper poll, you have to allow for every possibility. (Hint: ranges work better than absolutes.) At any rate, my answer--as it was the other day--f) 0%
Member Since: 8 novembre 2009 Posts: 4 Comments: 13508
Quoting kmanislander:
Another HH mission was scheduled for tonight but so far nothing in the air. If they cancelled they may be thinking of retasking as 99L appears to be reorganizing in earnest now.
I think they'll fly, but if they don't...it's good to have the ground OBS from you and others on GC. And, as always, your insight.
Member Since: 3 août 2005 Posts: 10 Comments: 5560
Quoting kmanislander:


If they did cancel they are probably rethinking that now LOL
Sky really looking ominous now.
Member Since: 9 octobre 2008 Posts: 0 Comments: 8323
Up to 80%.

Kinda contradicting to raise the odds and say 'has changed little in organization'

Think they noticed that the COC might be relocating.
Member Since: 8 juillet 2005 Posts: 259 Comments: 23882
Quoting stormwatcherCI:
NHC has it up to 80% now but no mention of recon. Don't know if it was canceled.


If they did cancel they are probably rethinking that now LOL
Member Since: Posts: Comments:
18Z GFDL will be posted to the ftp directory at ncep at 745PM
Member Since: Posts: Comments:
Quoting kmanislander:
Another HH mission was scheduled for tonight but so far nothing in the air. If they cancelled they may be thinking of retasking as 99L appears to be reorganizing in earnest now.
NHC has it up to 80% now but no mention of recon. Don't know if it was canceled.
Member Since: 9 octobre 2008 Posts: 0 Comments: 8323
ZCZC MIATWOAT ALL
TTAA00 KNHC DDHHMM
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT WED OCT 20 2010

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

1. SHOWERS AND THUNDERSTORMS ASSOCIATED WITH THE LOW PRESSURE SYSTEM
CENTERED ABOUT 140 MILES SOUTH OF GRAND CAYMAN HAVE CHANGED LITTLE
IN ORGANIZATION DURING THE LAST SEVERAL HOURS. UPPER-LEVEL WINDS
ARE FORECAST TO BECOME MORE CONDUCIVE FOR DEVELOPMENT OVER THE NEXT
DAY OR TWO...AND A TROPICAL DEPRESSION COULD FORM AT ANY TIME
TONIGHT OR THURSDAY. THERE IS A HIGH CHANCE...80 PERCENT...OF THIS
SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT
MEANDERS SLOWLY. INTERESTS IN THE NORTHWESTERN CARIBBEAN SEA
SHOULD CONTINUE TO MONITOR THE PROGRESS OF THIS DISTURBANCE.
REGARDLESS OF DEVELOPMENT...HEAVY RAINFALL IS POSSIBLE OVER THE
CAYMAN ISLANDS AND JAMAICA DURING THE NEXT COUPLE OF DAYS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER KIMBERLAIN/PASCH
NNNN

Member Since: Posts: Comments:
Quoting Jeff9641:
Tampa Shield GONE!!

http://www.coaps.fsu.edu/~maue/extreme/hwrf/invest99l.2010102018_wind.png
\

well that is closer to 12Z GFDL. I wonder what 18Z GFDL will look like
Member Since: Posts: Comments:
18Z HWRF doomcast


Member Since: Posts: Comments:
Another HH mission was scheduled for tonight but so far nothing in the air. If they cancelled they may be thinking of retasking as 99L appears to be reorganizing in earnest now.
Member Since: Posts: Comments:
Haven't been here in a while but here is my two cents on 99L.

Climatologically 99L is in a very favorable area for development this time of the year, add record TCHP, high SST's and a building anticyclone over 99L and we have trouble. Personally I believe we will have Hurricane richard within the next couple of days.

It becomes a very dangerous situation when a system like this meanders in the NW carribean, it could explode into a major hurricane within a couple of hours. This first focus should be on our friends in the yucatan, and caymans as this is already a factor in your weather and it could get very bad over the next 5 days. We will then shift our focus to long term. It is still way to early to speculate on track and strength however the long term track is split up into 2 scenarios

GFS, NOGAPS, and BAM's that drift this SW into Central america

GFDL, HWRF, CMC, ECMWF which brings this eventually northward towards GOM.

We should not be concerned until this develops, however, what the HWRF and GFDL are showing are both scary scenarios. IMO this might be our last major threat to the CONUS this year as a strong easterly flow has already setup over GOM.

Be prepared as next week things could get ugly

P.S. that GFDL run made me think of Wilma :(
Member Since: Posts: Comments:
Quoting CybrTeddy:
IMO the center might have reformed at ~17.2N 79.3W


Thats my thinking as well.
Member Since: Posts: Comments:
Quoting Saltydogbwi1:


Hey Kman looks like COC could be trying to organise around 81N17.5W what do you think?


If you read back through the blog from about 2 hours ago I posted about the new center shifting East. Those coordinates are close
Member Since: Posts: Comments:
Member Since: Posts: Comments:
Quoting kmanislander:
Winds here tonight will switch to NE


Hey Kman looks like COC could be trying to organise around 81W17.5N what do you think?
Member Since: Posts: Comments:
Member Since: Posts: Comments:
Winds here tonight will switch to NE

In fact my station already bouncing between ENE and NE now
Member Since: Posts: Comments:
IMO the center might have reformed at ~17.2N 79.3W
Member Since: 8 juillet 2005 Posts: 259 Comments: 23882
Quoting stormwatcherCI:
I got that from Cayman Retreat.


New center now under the deep convection. Winds at buoy 42057 switched to WNW about an hour ago and now NW indicating the low center is no longer to the West of that buoy which is located at 16.8 N and 81.5 W

Wind Direction (WDIR): NW ( 310 deg true ) Wind Speed (WSPD): 9.7 kts
Wind Gust (GST): 13.6 kts
Wave Height (WVHT): 3.0 ft
Dominant Wave Period (DPD): 5 sec
Average Period (APD): 4.5 sec
Atmospheric Pressure (PRES): 29.73 in
Pressure Tendency (PTDY): +0.00 in ( Steady )
Air Temperature (ATMP): 81.0 °F
Water Temperature (WTMP): 84.2 °F
Dew Point (DEWP): 77.2 °F
Heat Index (HEAT): 88.0 °F
Member Since: Posts: Comments:
Quoting kmanislander:


E to ENE actually
I got that from Cayman Retreat.
Member Since: 9 octobre 2008 Posts: 0 Comments: 8323
Quoting stormwatcherCI:
South Sound reporting E winds.


E to ENE actually
Member Since: Posts: Comments:

Viewing: 376 - 326

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

Local Weather

Mostly Cloudy
77 ° F
Nuageux