New Caribbean disturbance 93L a major concern; flooding in Asia kills over 200

By: Dr. Jeff Masters , 2:50 PM GMT on June 21, 2010

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A concentrated region of intense thunderstorms associated with a tropical wave has developed in the central Caribbean, a few hundred miles south of Puerto Rico. This disturbance was designated Invest 93L by NHC this morning, and has the best chance to become Tropical Storm Alex of any system we've seen so far this year. The disturbance is located near Buoy 42059, and this buoy has been reporting winds of 5 - 15 knots this morning. So far, pressures are not falling. Water vapor satellite loops show that 93L is embedded in a large region of moist air. Some dry continental air from North America is over the western Caribbean, but this dry air is too far away to interfere with development today and Tuesday. Wind shear is a low 5 - 10 knots. The high wind shear associated with the strong winds of the subtropical jet stream are over the northern Caribbean, too far north to interfere with development. Sea Surface Temperatures are plenty warm, a record 29 - 30°C. The Madden-Julian oscillation currently favors upward motion over the Caribbean, which will act to increase the chances of tropical storm formation this week. The Madden-Julian oscillation is a pattern of enhanced rainfall that travels along the Equator from west to east. The pattern has a wet phase with large-scale rising air and enhanced thunderstorm activity, followed by a dry phase with large-scale sinking air and suppressed thunderstorm activity. Each cycle lasts approximately 30 - 60 days. When the Madden-Julian oscillation is in its wet phase over a hurricane-prone region, the chances for tropical storm activity are greatly increased. The only negative for 93L would seem to be the lack of spin; the University of Wisconsin 850 mb relative vorticity analysis is showing only meager amounts of spin at 850 mb (roughly 5,000 feet in altitude.)


Figure 1. Morning visible satellite image of the central Caribbean disturbance 93L.

Forecast for 93L
NHC is giving 93L a 20% chance of developing into a tropical depression by Wednesday morning, which is a reasonable forecast. With wind shear expected to drop to low values less than 10 knots over the central and western Caribbean this week (Figure 2), I don't see any major impediments to the storm becoming a tropical depression by Friday. The ECMWF model is the most aggressive in developing this system, taking it into the Gulf of Mexico as a hurricane next week. The NOGAPS model keeps the storm weak and farther south, predicting that 93L will bring heavy rains to northern Honduras as a tropical disturbance or tropical depression on Friday and Saturday. The GFS model does not develop 93L. Expect 93L to bring flooding rains of 3 - 6 inches to Jamaica, eastern Cuba, and extreme southwestern Haiti on Wednesday. These rains will spread to the Cayman Islands and central Cuba by Thursday.


Figure 2. Predicted wind shear for Friday, June 25, as forecast by this morning's 2am EDT run of the GFS model. Shear is given in meters per second; multiply by about two to convert to knots. Low wind shear values less than 6 m/s (12 knots) are predicted for much of the Western Caribbean this week.

Elsewhere in the tropics
The tropical wave (92L) that brought heavy rains of 2 - 5 inches to Puerto Rico on Saturday has weakened and is no longer a threat to bring flooding rains to the Caribbean.

Floods in China and Burma kill over 200
The deadliest and most destructive weather-related disaster on the planet so far this year is occurring in southern China and northern Burma, where a week of heavy rains has caused flooding that has claimed over 200 lives. The death toll stands at 175 in China and 63 in Burma, with more than 100 people still missing in China. Damage so far in China has been estimated at $4.3 billion.


Figure 3. Tree branches hung on a bridge at Taining County, southeast China's Fujian Province, June 19, 2010. Taining recorded 225 mm (9 inches) of rain in six hours on Friday. Image credit: Xinhua/Jiang Kehong.

Montana tornado rips roof off entertainment complex
A EF-2 tornado with winds of at least 100 mph ripped the roof of an entertainment complex in Billings, Montana on Sunday, causing up to $15 million in damage. No injuries were reported. It was the strongest tornado to hit the Billings area since 1958.


Figure 4. Video of the Billings tornado shows an impressive debris cloud (and a few expletives not deleted!) The clear slot on the right of the tornado is likely associated with the parent thunderstorm's rear flank downdraft.

Wind and ocean current forecast for the BP oil disaster
Southeast to east winds less than 10 knots will blow in the northern Gulf of Mexico today through Friday, according to the latest marine forecast from NOAA. The resulting weak ocean currents should cause little motion of the oil slick, according to the latest trajectory forecasts from NOAA and the State of Louisiana. The long range outlook is uncertain, as the tropical wave over the central Caribbean could enter the Gulf of Mexico early next week and develop into a tropical storm.

Resources for the BP oil disaster
My post, What a hurricane would do the Deepwater Horizon oil spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA's interactive mapping tool allows one to overlay wind and ocean current forecasts, oil locations, etc.
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami

Jeff Masters

Billings, MT tornado (StormTeam)
Photo taken from approx. 5-6 miles east. Video here: http://www.youtube.com/watch?v=8429C0-LSlo
Billings, MT tornado

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Has the model consensus changed in the last 24 hours? Looks about the same with maybe one or two going more Central GOM. Which ones show a path toward Florida?
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3827. RJT185
Quoting cg2916:


Don't see it.


Ditto.
Member Since: August 31, 2009 Posts: 3 Comments: 252
There is no surface circulation, but as of 5am, there continues to be a clearly defined Upper-level Circulation, about 100-350MB. Not quite mid-level.
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3825. cg2916
Quoting saintsfan06:
How fast is 93L moving?


About 10 MPH.
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3824. cg2916
Quoting DestinJeff:
Due south of the DR / Haiti border I see what looks like a spin ... don't know about low level, but there is an appearance there of a spin.



Don't see it.
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How fast is 93L moving?
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3822. Drakoen
The bipolarity in the models represents the various potential solutions that could occur in what is right now a complex and ambiguous situation.
Member Since: October 28, 2006 Posts: 57 Comments: 30830
3820. cg2916
There is no COC because there is no LLC.
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3819. GetReal
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Quoting Jeff9641:


On the visible it appears to be SE of Haiti and S of DR. 93L is getting more compact and not so broad compared to yesterday.

There appears to be a spot with no convection
but what point do you actually see clouds at the SAME level in the atmosphere rotating around and what is the approximate diameter of that rotation? A circulation is a circle after all..
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3816. pottery
Quoting sailingallover:


Shear maps and forecasts a like any other and prone to change and error. When you see the higher cloud tops getting pushed off in one direction pretty sure sign of shear. Shear is easy to spot on Sat pics because it is the top layer feature. Yesterday evening some of93L's convection moved north and got sheared into what is now the big streamer of clouds comming out the North side of the DR and going to the NE out into the atlantic.

Ah! But your interpretation of that is contrary to what Kman and StormW have recently explained.
I am thinking like you, but dont have the expertise to justify it.
Interesting stuff..........
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Good Morning everyone from SWLA...:) Good Morning Storm :) good to see ya! :) Waitin for this thing to develop is like pulling yer hair out! lol !!
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3814. Drakoen
Quoting hurricane23:


Models right now aren't doing much of anything with this disturbance.


Yes they are. Just not as quickly as some would like... lol
Member Since: October 28, 2006 Posts: 57 Comments: 30830
3813. pottery
Quoting Drakoen:


Look at the bottom of the image that is the time the pass was taken.

Got it.
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3812. RJT185
Quoting hurricane23:


Models right now aren't doing much of anything with this disturbance.



There's not much to work with, the potential is brimming and unprecedented, but the actual ingredients aren't mixing.
Member Since: August 31, 2009 Posts: 3 Comments: 252
Guys, you are gonna love this one...8:30am radio newscast for local station..."There is a tropical disturbance in the East Carribean that National Weather Service says could intensify over the next 48 hours as it moves TOWARDS MEXICO."
Welcome to Florida weather casting for the tourists. I know a couple of runs on the 2am models showed it going towards the Yucatan, but a couple recurved it back towards Florida. With this kind of weather reporting, no wonder so many in Florida get caught at the last minute unprepared.
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3810. Walshy
Quoting hurricane23:


Models right now aren't doing much of anything with this disturbance.



???
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22/1145 UTC 15.5N 70.1W TOO WEAK 93L -- Atlantic
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3808. Drakoen
Whether or not 93L goes over the Yucatan or moves through the channel depends on how strong it becomes once it gets pass Jamaica. A stronger system will tend to go more poleward and feel the affects of the trough going through the Channel or even western Cuba.
Member Since: October 28, 2006 Posts: 57 Comments: 30830
Quoting DestinJeff:


you got that right! but then day after day, here we are.


I am a WU addict.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
3806. Crawls
Quoting 7544:
wow could this be right 2 states get hit at once lol

Link


Lets hope not. Not a pretty sight!
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Quoting Jeff9641:


Maybe that is what i am seeing is a mid level circulation. Visible presentation does look good though and we could have this a the surface later today.


Models right now aren't doing much of anything with this disturbance.
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Quoting CaneWarning:
Watching a tropical cyclone try to develop is frustrating. It's much more fun to track after it has developed!


Right now it is just a guessing game.
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Quoting pottery:

This is what I am questioning.
Can the shear-maps be wrong??
When I look at the loops, I see something that makes me think that the system is being stressed from winds.
Having said that (and accepting that I am lacking in experience here), I find it strange that the area all over the East Carib and extending into the Atl east of Trinidad has lost so much moisture overnight.
Supposed to build during DMax.........not shrink??


Shear maps and forecasts a like any other and prone to change and error. When you see the higher cloud tops getting pushed off in one direction pretty sure sign of shear. Shear is easy to spot on Sat pics because it is the top layer feature. Yesterday evening some of93L's convection moved north and got sheared into what is now the big streamer of clouds comming out the North side of the DR and going to the NE out into the atlantic.
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Watching a tropical cyclone try to develop is frustrating. It's much more fun to track after it has developed!
Member Since: April 26, 2009 Posts: 3 Comments: 3667
3800. Drakoen
Quoting pottery:

I see June 22 1200 UTC...
??


Look at the bottom of the image that is the time the pass was taken.
Member Since: October 28, 2006 Posts: 57 Comments: 30830
Met Service of Jamaica

June 22, 2010 at 5:00 a.m.

LOCAL WEATHER FORECAST

SIGNIFICANT FEATURE… Tropical Wave west of Jamaica.

Comment
The Tropical Wave west of Jamaica will move toward the west, farther away from the island. Another Tropical will be just east of Jamaica late this evening.


TODAY'S FORECAST
This Morning… Isolated showers mainly across sections of eastern parishes. Partly cloudy elsewhere.

This Afternoon… Scattered showers and thunderstorms across most parishes.

Tonight… Lingering showers across northern parishes. Partly cloudy elsewhere.


3-DAYS FORECAST (starting tomorrow)
Wed/Thurs… Periods of showers and thunderstorm across the island.
Fri… Scattered showers and isolated thunderstorms mainly over central and western parishes.

Regionally… Trough and Tropical Waves over the central Caribbean will continue to generate unstable weather conditions across the region.

rlb
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3797. pottery
Quoting Drakoen:


That pass if from yesterday morning. If you look at the bottom of the image you will get the time the image was taken. 14:38UTC has not occured yet.

I see June 22 1200 UTC...
??
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3796. IKE
Latest NOGAPS takes it into the Yucatan peninsula.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Looks like my computer lagged.. Apologize for the double post all.
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93L is starting too look for good now
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Quoting Drakoen:


The descending pass comes out in the morning and has not loaded yet. Your image is showing the ascending pass.


Made that mistake yesterday, your correct ASCAT has yet to make its descending node pass. Also a little trivia, the reason they call it 'ascending' and 'descending' is because of ASCATs orbital track. Here's the orbital track of space shuttle Discovery on STS-121



When it goes uphill on the track, its called the 'ascending' node, whenever its on the 'descending' track its called the descending node.

Sorry for the off topic.
Member Since: July 8, 2005 Posts: 259 Comments: 24575
3791. pottery
Quoting nrtiwlnvragn:
Most of the information I have found on the lack of cyclogenesis in the eastern carribean focuses on the low level jet. Several papers:

Variability of the Caribbean Low-Level Jet and its relations to climate

A Climatic Feature of the Tropical Americas: The Trade Wind Easterly Jet

Winter and Summer Structure of the Caribbean Low-Level Jet


AHhhhh!
Thanks. Will study those.....
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Wave still remains poorly organized with no surface developments just a well defind mid level rotation as of this morning. Development should be slow.
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3789. Drakoen
Quoting HurricaneFCast:


Also.. the other portion of the ASCAT pass which covered the majority of the area of convection shows not much action on the east side of the system, either.


That pass if from yesterday morning. If you look at the bottom of the image you will get the time the image was taken. 14:38UTC has not occured yet.
Member Since: October 28, 2006 Posts: 57 Comments: 30830


Also.. the other portion of the ASCAT pass which covered the majority of the area of convection shows not much action on the east side of the system, either.
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Most of the information I have found on the lack of cyclogenesis in the eastern carribean focuses on the low level jet. Several papers:

Variability of the Caribbean Low-Level Jet and its relations to climate

A Climatic Feature of the Tropical Americas: The Trade Wind Easterly Jet

Winter and Summer Structure of the Caribbean Low-Level Jet
Member Since: September 23, 2005 Posts: 15 Comments: 11343


Also.. the other portion of the ASCAT pass which covered the majority of the area of convection shows not much action on the east side of the system, either.
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3784. aquak9
Quoting Tazmanian:
can we for get about the The John Hope rule are we be saying that with evere storm that comes a long too me its starting to get vary annyoing


"pin hole eye" gets annoying too, Taz, but I just wanted to know what it was. I won't be asking that question over and over and over and over like some people.
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Also.. the other portion of the ASCAT pass which covered the majority of the area of convection shows not much action on the east side of the system, either.
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Quoting DestinJeff:


you might be looking at the 00Z .. the 6Z takes it further west and not anywhere near as strong
Link


Strength being the key.
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3780. ssmate
Quoting StormW:
Just got looking at some things (Drak, jump on board here if you wish)...I remember, I think it was last year, we had a system that didn't appear to be under any shear, but there was some at around 700MB if I remember...could be one thing here, as if you look at the vorticity map, doesn't appear to be too vertically stacked.

Water vapor imagery indicates some slight presence of dry air to the east of the "center" also.

WV LOOP
Storm, I remember that situation because you explained to me that storms can sometimes be effected by 'invisible' shear. I knew then that I would never be able to understand hurricanes.
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AL, 93, 2010062212, , BEST, 0, 153N, 723W, 25, 1010, WV
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3778. aquak9
thank you walshy :)

figured it was something like that- kman's explanation prefaced it, all makes good sense
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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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