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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78. IKE
Quoting Drakoen:


Link


Thanks...oh my.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Thanks Dr. Masters, that post was like a cold shower for a lot of folks in this blog. Until an LLC is confirmed this is anyone's guess. I'm surprised at the amount of doom-casting that is/was taking place over 93L.
Member Since: August 31, 2009 Posts: 3 Comments: 252
Quoting smmcdavid:
Thanks for the update Dr. Masters... I think you are going to be awfully busy this season.

Question for those who actually understand all this: so the reason 93L probably won't develop until later this week is because the wind shear is still high now, but forecasted to decrease? Be nice to me please... :)


It is complying with the John Hope rule and is waiting to get past 75 West LOL
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Quoting connie1976:
That tornado video was amazing!! Those people were brave....I would have had a heart attack!!....I am so glad that I live in Florida and that we don't have to deal with those things too often...




I bet the people of Montana said the same thing. They don't get as much as Florida.
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hurricane alex
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Quoting RecordSeason:
57:

The number one thing hindering it right now is actually geographic location.

It is in an area notorious as a dead zone for development, and it is close to land of SA.
Well, I don't see any current reason why it won't develop. It's not close enough to SA for its future circulation to be affected.
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Quoting jpsb:
Yes I saw that but 93L is just a new designation. 93L is very close to where 92L would be now. Just curious.


This is a separate entity; what's left of 92L is north of this invest
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we get a lot of tornadoes in nw fla but they seem lower in intensity.
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Quoting IKE:
Can someone be real nice and post the link that shows the SHIPS shear forecast and longitude/latitude?

TIA!


Link
Member Since: October 28, 2006 Posts: 57 Comments: 29714
I didn't know that we had that many tornados on average....I was born in orlando, but moved to South Florida 4 yrs ago and the only tornado I have ever seen was a water spout in the keys last year...I take that back....i have seen tornados that never touched the ground...but would those be considered tornados?
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Quoting smmcdavid:
Thanks for the update Dr. Masters... I think you are going to be awfully busy this season.

Question for those who actually understand all this: so the reason 93L probably won't develop until later this week is because the wind shear is still high now, but forecasted to decrease? Be nice to me please... :)

I am having the same thought as you,,, if everything is in 93L's favor, should it develop quickly?
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Quoting helove2trac:
Why is it taking so long for it to get in the gulf if must be moving slow
I think the models are picking up on an area of high vorticity moving into the caribbean, snatching up the moisture from 93l, then developing. That would explain the slow timing of it all.
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Quoting btwntx08:

thats 00z run actually

My bad.
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The Navy site has 93L at 1010 mb and 25 knots.

That low must be very broad and quite shallow as there is nothing at 850 mb or above.
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Quoting leo305:


who cares if its an invest or not.. tropical cyclones are not machines that once are activated invest it automatically has to be tracked, and if its not , you can't track it.. They can spin up out of nothing.. I have been tracking for a while.. and I can tell you even the faintest spin in an area of low shear with high water and moisture content can turn into something.. I'm not saying 92L is going to turn into anything, Im just saying it's developing some convection.


Ok that is fine, I am just saying that with as fast as this blog is going to be going; 99% of the people will be talking about 93L. Any post about 92L just would seem out of place is all.
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Quoting Drakoen:
getting that arc look to it
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93L has a 30% chance... but TBH the models want to pick up on more moisture and a trough of low pressure moving NW from the ITZ by Weds morning in the SE Carribean then move to near Jamaica-Caymans by Friday morning. A breakdown in the ridge over the SE U.S. by this weekend could bring something NW or N...way to early to tell and wont give % out yet.
93L should move W to WNW into central america by Thursday or get intrained into the developing low behind it (if there is 1).
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58. IKE
Can someone be real nice and post the link that shows the SHIPS shear forecast and longitude/latitude?

TIA!
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Thanks for the update Dr. Masters... I think you are going to be awfully busy this season.

Question for those who actually understand all this: so the reason 93L probably won't develop until later this week is because the wind shear is still high now, but forecasted to decrease? Be nice to me please... :)
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Quoting connie1976:
That tornado video was amazing!! Those people were brave....I would have had a heart attack!!....I am so glad that I live in Florida and that we don't have to deal with those things too often...
Depends on where you live in Fl. Where I'm from we get as many tornadoes as tornado alley. Albeit, they're not as powerful on average.
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Met Service of Jamaica
June 21, 2010 at 5:00 a.m.

LOCAL WEATHER FORECAST

SIGNIFICANT FEATURE Tropical wave just west of Jamaica

Comment
The Tropical Wave will move away from the island by tonight.
A Trough should linger across the central Caribbean.


TODAY'S FORECAST
This Morning… Partly cloudy especially over western parishes.
This Afternoon… Scattered showers and thunderstorms
across most parishes.
Tonight… Partly cloudy.


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

Regionally… Tropical Waves and troughs moving across
the Caribbean accompanied by large areas of showers and thunderstorms.

pef
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Quoting Hurricanes101:


It has a 0% chance of developing, it was deactivated and we have 93L; something that is a real threat to develop

Talking about 92L; a deactivated invest just seems to be a bit of a waste of time IMO


who cares if its an invest or not.. tropical cyclones are not machines that once are activated invest it automatically has to be tracked, and if its not , you can't track it.. They can spin up out of nothing.. I have been tracking for a while.. and I can tell you even the faintest spin in an area of low shear with high water and moisture content can turn into something.. I'm not saying 92L is going to turn into anything, Im just saying it's developing some convection.
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Quoting helove2trac:
Why is it taking so long for it to get in the gulf if must be moving slow


That is a good point, is it really supposed to take 10 days for this system to make landfall from the SE Caribbean?

Charley made it there in 4, is steering really that weak?
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Quoting Hardcoreweather2010:
93L model runs


oops, not good!
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Quoting Drakoen:


I highly doubt that. 92L has very little to do with 93L.


I said instrumental in setting it up.

It's setting up the environment ahead of 93L by lowering pressures in the western Caribbean and cleaning out any dry air that was in the area. As a result, 93L now has a very moist environment out ahead of it, and as ex-92L starts to slow down out in front, it will only add to the piling up of air in the western Caribbean and increase convergence.
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Why is it taking so long for it to get in the gulf if must be moving slow
Quoting leo305:


Um I know the chances of it developing are almost 0, but it's still something to watch.. you can't tell someone to stop tracking something just because its "dead" when there is still a broad spin assosiated with it, and it's getting some convection on it.. This blog is meant for tracking tropical weather..


It has a 0% chance of developing, it was deactivated and we have 93L; something that is a real threat to develop

Talking about 92L; a deactivated invest just seems to be a bit of a waste of time IMO when we have something that has a much higher chance of developing
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47. IKE
Quoting Levi32:


It's remnants are instrumental in this situation though. It's setting up 93L.


I know that...I'm just saying it's RIP.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
That tornado video was amazing!! Those people were brave....I would have had a heart attack!!....I am so glad that I live in Florida and that we don't have to deal with those things too often...
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Quoting Hurricanes101:


92L is dead and gone, forget about 92L please



Um I know the chances of it developing are almost 0, but it's still something to watch.. you can't tell someone to stop tracking something just because its "dead" when there is still a broad spin assosiated with it, and it's getting some convection on it.. This blog is meant for tracking tropical weather..
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Quoting CybrTeddy:
CMC develops it.. far less aggressive than the NOGAPS or the ECMWF.

Link


That's the wave behind it southeast of the windwards.
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Quoting Becca36:
Thank you. I hope this stays out of the Gulf...

Me too. Nobody wants this to happen.

00Z ECMWF
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Quoting Levi32:


It's remnants are instrumental in this situation though. It's setting up 93L.


I highly doubt that. 92L has very little to do with 93L.
Member Since: October 28, 2006 Posts: 57 Comments: 29714
Quoting leo305:


CMC does not develop 93L it develops the wave behind it

http://moe.met.fsu.edu/cgi-bin/cmctc2.cgi?time=2010062100&field=850mb+Vorticity&hour=Animat ion
Mhm. It initiates the wave it develops over 200 miles east of the outer periphery of 93l. All the energy should combine though.
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Thanks Dr. Masters

Looks like the majority who took the poll and chose the week of 6/27 might be proven right after all or wrong if 93L ramps up quickly.
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Thank you Dr. Masters, I read the your whole blog and couldn't agree more.
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Member Since: October 28, 2006 Posts: 57 Comments: 29714
Quoting IKE:
92L is dead. Forget 92L...please.


It's remnants are instrumental in this situation though. It's setting up 93L.
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Ultra low shear, Record SST's. Those models calling for a weak storm are out to lunch IMO.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
Quoting CybrTeddy:
CMC develops it.. far less aggressive than the NOGAPS or the ECMWF.

Link


CMC does not develop 93L it develops the wave behind it

http://moe.met.fsu.edu/cgi-bin/cmctc2.cgi?time=2010062100&field=850mb+Vorticity&hour=Animation
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It appears that the operational ECMWF is an outlier to the rest of its ensemble members:

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Quoting leo305:
92L is trying to get some convection on it.. it's still there you can see a weak spin on the visible, as it drifts W/WSW


92L is dead and gone, forget about 92L please

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hmmm....Dr M's update seems a bit subdued compared to some of the "animated" postings we have seen this morning.
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Thx Doc...
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Thanks for the update! That is one impressive tornado video!
Member Since: April 26, 2009 Posts: 3 Comments: 3667

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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.