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

By: Dr. Jeff Masters , 7:11 PM GMT on October 20, 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: 276 - 226

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

276. beell
Trough digging SSE (maybe not as much SE as modeled) from the central US. Trough base just nosing out into the north central GOM near the end of the WV loop.

Strong enough and deep enough to catch 99L?
Maybe...

PSU e-Wall WV Loop
Member Since: Posts: Comments:
Complete Update

Florida appears to be the target of choice in the new model runs.



AOI
AOI AOI AOI

AOI AOI AOI

TS BUSTED FORECAST ALIBI
Member Since: Posts: Comments:
274. xcool
yepp
Member Since: Posts: Comments:
273. HadesGodWyvern (Mod)
Philippines Atmospheric Geophysical Astronomical Service and Administration
Tropical Cyclone Bulletin #20
TYPHOON JUAN (MEGI)
5:00 AM PhST October 20 2010
=======================================

Typhoon "JUAN" continues to move away from the country.

At 4:00 AM PhST, Typhoon Juan (Megi) located at 19.1°N 117.4°E or 300 km west northwest of Laoag City has 10 minute sustained winds of 95 knots with gustiness up to 110 knots. The cyclone is reported as moving north northeast slowly

Additional Information
========================
With this development and unless re-curvature occurs, this is the final bulletin for this weather disturbance.

However, residents along the coastal areas of Western Luzon are alerted of possible storm surges.
Member Since: Posts: Comments:
Heading home too. Later folks!

Don't go bug eyed waiting for it to explode tonight!
Member Since: Posts: Comments:
Quoting FLWaterFront:


It does seem that way, yes.

But the Floridacasters have got to have one more shot at glory before the season is done. Or they might even get two, if something moves in from the CATL to the S-CAR in about ten days, as Levi has been talking about.

However, if all that fails then just as every good sports fan knows..

"There's always next year!"


I think the thing that is poking me in the ribs right now is the 5-day model runs showing a powerful hurricane moving into the southern GoM. I mean really, 5 days from now? Yet we're looking at a healthy invest and told not to believe those 5 day models, believe other ones instead.

It is frustrating.
Member Since: Posts: Comments:
Quoting Levi32:
Out until later.


Likewise
Member Since: Posts: Comments:
Out until later.
Member Since: Posts: Comments:
Quoting CosmicEvents:
I'm gonna' take a shot and go with B.


Ah, they are twice as sweet when it lands in your lap. Are you sharing with them? LOL
Member Since: Posts: Comments:
Quoting BLee2333:
Hey Levi,

Did you happen to take note of the CARIB on the last frame of the ECMWF you posted?

We're not done...


Yup. The pattern favors the eastern Caribbean next.
Member Since: Posts: Comments:
Quoting KennyNebraska:


He'll be a king for a time, I believe that for sure. But as soon as he peeks into the Gulf, he'll be sheared to death.


It does seem that way, yes.

But the Floridacasters have got to have one more shot at glory before the season is done. Or they might even get two, if something moves in from the CATL to the S-CAR in about ten days, as Levi has been talking about.

However, if all that fails then just as every good sports fan knows..

"There's always next year!"
Member Since: Posts: Comments:
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




can we plzs stop with the polls plzs
Member Since: Posts: Comments:
Hey Levi,

Did you happen to take note of the CARIB on the last frame of the ECMWF you posted?

We're not done...
Member Since: Posts: Comments:
257. xcool


maker two time gfs shows this flurries
Member Since: Posts: Comments:

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
Member Since: Posts: Comments:
Quoting IKE:
SYNOPSIS FOR CARIBBEAN SEA AND TROPICAL N ATLC FROM 07N TO 22N
BETWEEN 55W AND 65W
530 PM EDT WED OCT 20 2010

.SYNOPSIS...LOW PRES 1008 MB NEAR 17N82W DRIFTS SLOWLY S THROUGH
FRI THEN MOVES W INTO CENTRAL AMERICA NEAR HONDURAS AND
NICARAGUA OVER THE WEEKEND...POSSIBLY AS A TROPICAL CYCLONE.

............................................


SYNOPSIS FOR THE GULF OF MEXICO
430 PM CDT WED OCT 20 2010

.SYNOPSIS...A HIGH PRESSURE CENTER WILL MEANDER OVER THE
NORTHERN GULF WATERS THROUGH THU NIGHT THEN SHIFT N OF THE AREA
FRI WITH A RIDGE DISSECTING THE GULF FROM NW FLORIDA TO THE BAY
OF CAMPECHE FRI NIGHT THROUGH MON.


New center forming up now Ike. See here

Note the low level inflow to the South of the deep convection as evidenced by the fine "streamer" lines.
Member Since: Posts: Comments:
Quoting FLWaterFront:


Yes, probably.

But the question is will he wind up as King Richard or just Little Richard?

Time will tell.


He'll be a king for a time, I believe that for sure. But as soon as he peeks into the Gulf, he'll be sheared to death.
Member Since: Posts: Comments:
252. IKE
SYNOPSIS FOR CARIBBEAN SEA AND TROPICAL N ATLC FROM 07N TO 22N
BETWEEN 55W AND 65W
530 PM EDT WED OCT 20 2010

.SYNOPSIS...LOW PRES 1008 MB NEAR 17N82W DRIFTS SLOWLY S THROUGH
FRI THEN MOVES W INTO CENTRAL AMERICA NEAR HONDURAS AND
NICARAGUA OVER THE WEEKEND...POSSIBLY AS A TROPICAL CYCLONE.

............................................


SYNOPSIS FOR THE GULF OF MEXICO
430 PM CDT WED OCT 20 2010

.SYNOPSIS...A HIGH PRESSURE CENTER WILL MEANDER OVER THE
NORTHERN GULF WATERS THROUGH THU NIGHT THEN SHIFT N OF THE AREA
FRI WITH A RIDGE DISSECTING THE GULF FROM NW FLORIDA TO THE BAY
OF CAMPECHE FRI NIGHT THROUGH MON.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting KennyNebraska:


It's probably going to RI just like the others have. This time tomorrow, it will be Richard and then some.


Yes, probably.

But the question is will he wind up as King Richard or just Little Richard?

Time will tell.
Member Since: Posts: Comments:
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
I'm gonna' take a shot and go with B.
Member Since: Posts: Comments:
Quoting Levi32:


12z initial position on the ECMWF is perfectly fine, and the pressure was up at 1008-1009mb at that time. Nothing wrong with that initialization.



I don't know. I'm not a met. But advancing through the next 36 hours of the ECMWF it just seems to me that they have it meandering for too long at too high a pressure.
Member Since: Posts: Comments:
Quoting Levi32:


Yeah it's a case of a couple vortices rotating around a mean center, but we may be very close to seeing one main center develop this evening and strengthen if it can stay close to the convection.
thanks, Another thing is that you mentioned that the gfs is now suggesting that(if 99L forms into Richard) Shary could form over in the eastern caribbean.
Member Since: Posts: Comments:
Quoting BLee2333:


Guess you don't remember the long lived 95L (I could have the # wrong) which crossed nearly the ENTIRE ATL basin, crossed FL into the GOM, LOOKED like a TS over NO, looped through LA, MS, AL, GA, back into the the GOM, crossed MEX, and I believe may have gotten renumbered and eventually named in the PAC...

There were comments joking about it eventually hitting Japan as a supertyphoon!
Since Wilma, every single L that's come down the pike has gotten compared to Wilma. It's how things go around here. Give it another 10 years or so, another 200 L's, and maybe the references will stop.....maybe.
Member Since: Posts: Comments:
Quoting Levi32:


Yeah, it's nosing under the cirrus now. It will be interesting to see what happens during diurnal max tonight. My guess is you're probably going to be hoping this thing doesn't start drifting north lol.


It's probably going to RI just like the others have. This time tomorrow, it will be Richard and then some.
Member Since: Posts: Comments:
Here we go. Wind shift at 42057 from WSW to WNW.

We need to see another update to make sure the shift was not a temporary indication based upon the single snapshot when the buoy updated.

Direction (WDIR): WNW ( 290 deg true ) Wind Speed (WSPD): 7.8 kts
Wind Gust (GST): 9.7 kts
Wave Height (WVHT): 3.3 ft
Dominant Wave Period (DPD): 5 sec
Average Period (APD): 4.2 sec
Atmospheric Pressure (PRES): 29.72 in
Pressure Tendency (PTDY): -0.06 in ( Falling )
Air Temperature (ATMP): 80.8 °F
Water Temperature (WTMP): 84.2 °F
Dew Point (DEWP): 76.1 °F
Heat Index (HEAT): 87.1 °F
Member Since: Posts: Comments:
Quoting KennyNebraska:


Yeah Levi, but one big problem with this model run is the 1200Z for today's date. That is too far west, and the mb pressure too high by a full 2 mb.

You know what this means, don't you?


12z initial position on the ECMWF is perfectly fine, and the pressure was up at 1008-1009mb at that time. There is nothing wrong with that initialization.

Member Since: Posts: Comments:
Quoting kmanislander:


Take a look at the image I just posted. The "spinner" has disappeared in the cloud deck.


Yeah, it's nosing under the cirrus now. It will be interesting to see what happens during diurnal max tonight. My guess is you're probably going to be hoping this thing doesn't start drifting north lol.
Member Since: Posts: Comments:
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
Member Since: Posts: Comments:
Quoting Levi32:
12z ECMWF is catching on now, finally, along with the rest of the models. Amazing how the logical track and development idea is unfolding before our eyes when every computer said otherwise.



Yeah Levi, but one big problem with this model run is the 1200Z for today's date. That is too far west, and the mb pressure too high by a full 2 mb.

You know what this means, don't you?
Member Since: Posts: Comments:
Quoting WeatherNerdPR:

Now I remember! It was TD#5, wasn't it?


May have been. It's been a long season and I've lost track.
Member Since: Posts: Comments:
Quoting BLee2333:


LOL!

The "little wave that could"! (Or could not...)

No, it wasn't Bonnie, because this never got named in the ATL.

Now I remember! It was TD#5, wasn't it?
Member Since: Posts: Comments:
The convection is on the east side of the larger, broad circulation. The smaller vortex has rotated around the larger circulation and moved under the convection. Some convection is also flaring up on the south side of the broad circulation.
Member Since: Posts: Comments:
Quoting Levi32:


Yeah it's a case of a couple vortices rotating around a mean center, but we may be very close to seeing one main center develop this evening and strengthen if it can stay close to the convection.


Take a look at the image I just posted. The "spinner" has disappeared in the cloud deck.
Member Since: Posts: Comments:
Quoting HurricaneDean07:
so levi, what you're saying is that the main circulation is making the other vortexes spin around it.


Yeah it's a case of a couple vortices rotating around a mean center, but we may be very close to seeing one main center develop this evening and strengthen if it can stay close to the convection.
Member Since: Posts: Comments:
Quoting HurricaneDean07:
so levi, what you're saying is that the main circulation is making the other vortexes spin around it.


Not so much around the actual center, but more like a mini FW effect of vortices within a greater broader low.
Member Since: Posts: Comments:
Quoting HurricaneDean07:
wait correction, the circulation is getting tucked under the convection. very confusing concept when it comes to this.


Yes, see this image below showing a new center forming up near 17 N and 81 W

Member Since: Posts: Comments:
Quoting kmanislander:


I agree with you in large part that a new center is taking over but the "spinner" in my opinion is what remains of the actual true center so far, to the extent that 99L can be said to have had a true center being so broad.

In the final analysis it comes back to the same thing. We both agree on what the current state appears to be migrating to.


Yes I agree that spinner was the main center previously, and then it "lost hold" and left the actual center and started rotating around, likely due to the convective cluster that has been in proximity to it for some time now.
Member Since: Posts: Comments:
wait correction, the circulation is getting tucked under the convection. very confusing concept when it comes to this. nevermind
Member Since: Posts: Comments:
Quoting Levi32:
As mentioned earlier, the dominant surface vortex is being drawn east now because it is not the main center, but is rotating about a mean circulation center that has been northeast of it during the afternoon. On visible imagery you can clearly see the circulation as a whole is trying to tighten eastward towards the convective cluster, and for now is broad with multiple vortices as a secondary one is developing closer to the convection, northeast of what is currently still the most obvious spinner on satellite imagery.

This also shows how 99L was not diving SSE earlier, because the dominant vortex is not the actual center of the system. Considering the circulation as a whole, movement has been nearly stationary or a very slight drift southeastward throughout the day so far.
so levi, what you're saying is that the main circulation is making the other vortexes spin around it.
Member Since: Posts: Comments:
Quoting Levi32:
As mentioned earlier, the dominant surface vortex is being drawn east now because it is not the main center, but is rotating about a mean circulation center that has been northeast of it during the afternoon. On visible imagery you can clearly see the circulation as a whole is trying to tighten eastward towards the convective cluster, and for now is broad with multiple vortices as a secondary one is developing closer to the convection, northeast of what is currently still the most obvious spinner on satellite imagery.

This also shows how 99L was not diving SSE earlier, because the dominant vortex is not the actual center of the system. Considering the circulation as a whole, movement has been nearly stationary or a very slight drift southeastward throughout the day so far.


I agree with you in large part that a new center is taking over but the "spinner" in my opinion is what remains of the actual true center so far, to the extent that 99L can be said to have had a true center being so broad.

In the final analysis it comes back to the same thing. We both agree on what the current state appears to be migrating to.
Member Since: Posts: Comments:
Yes, I have that one. Crank up the speed & zoom way in - coc is very clear.
Member Since: Posts: Comments:

Viewing: 276 - 226

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

Overcast
52 °F
Overcast