93L slow to develop, but bringing heavy rains to Haiti

By: Dr. Jeff Masters , 1:50 PM GMT on June 22, 2010

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A modest region of intense thunderstorms (Invest 93L) is over the central Caribbean, a few hundred miles south of Hispaniola. This disturbance has the best chance to become Tropical Storm Alex of any system we've seen so far this year. We don't have any buoys near 93L, but pressures at the ground stations surrounding the storm are not falling. A pass of the ASCAT satellite over the Central Caribbean at 9:45 pm EDT last night revealed a modest wind shift associated with 93L, but nothing at all close to a surface circulation. Top surface winds seen by ASCAT were 15 - 20 mph. Water vapor satellite loops show that 93L is embedded in a large region of moist air. The atmosphere over the Caribbean has moistened over the past day, which should aid development of 93L. 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, but close enough to provide good upper-level outflow for the storm. Visible satellite loops show high level cirrus clouds streaming away from 93L to the northeast, evidence of the upper-level outflow channel that is developing to the storm's north. Sea Surface Temperatures are plenty warm, a record 29 - 30°C. The Madden-Julian oscillation (MJO) 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 main negative for 93L continues to be lack of spin. The University of Wisconsin 850 mb relative vorticity analysis is showing that spin at 850 mb (roughly 5,000 feet in altitude) has increased over the past day, but 93L needs to acquire additional spin before it can grow more organized. I speculate that it is this lack of spin that contributed to the loss of much of 93L's heavy thunderstorm activity last night. The storm is now going through a cycle where it is building another respectable mass of heavy thunderstorms, and the increased inflow of low-level air that will feed these thunderstorms will likely enhance 93L's spin today. The Hurricane Hunters are on call to investigate 93L on Wednesday afternoon.


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

Forecast for 93L
NHC is giving 93L a 40% chance of developing into a tropical depression by Thursday morning, which is a reasonable forecast. Given the storm's current lack of spin and relatively modest amount of heavy thunderstorms, the earliest I'd expect 93L to become a tropical depression would be Wednesday afternoon, with Thursday more likely. Wind shear is expected to be low, less than 10 knots, over the central and western Caribbean this week. Water temperatures will be warm, dry air absent, and the MJO favorable. I don't see any major impediments to the storm becoming a tropical depression by Thursday, and it is a bit of a surprise to me that the computer models have been reluctant to develop 93L. The GFS, NOGAPS, and UKMET models do not develop 93L, and the ECMWF model doesn't develop 93L until after it crosses the Yucatan Peninsula and enters the Gulf of Mexico in a about a week. The current (2am EDT) run of the GFDL model predicts 93L will be a weak tropical storm in the Gulf of Mexico in five days; its previous run had 93L as a major hurricane in the Gulf. Given all this model reluctance and the current disorganization of 93L, I give the storm a low (less than 20% chance) of becoming a hurricane in the Caribbean. Expect 93L to bring flooding rains of 3 - 6 inches to Jamaica, eastern Cuba, and southwestern Haiti today through Wednesday. These rains will spread to the Cayman Islands and central Cuba by Thursday, and western Cuba and Mexico's Yucatan Peninsula on Friday. The current run of the SHIPS model has 93L slowing down late this week to a forward speed of just 6 knots (7 mph) from its current speed of about 10 mph, in response to a weakening in the steering currents. A trough of low pressure is expected to swing down over the Eastern U.S. early next week. If this trough is strong enough and 93L develops significantly, the storm could get pulled northwards and make landfall along the northern Gulf of Mexico coast in the oil spill region. This is the solution of the Canadian GEM model. If 93L stays weak and/or the trough is not so strong, the storm would get pushed west-northwestwards towards the Texas coast. This is the solution of the ECMWF model. The amount of wind shear in the Gulf of Mexico next week is highly uncertain. There is currently a band of high shear near 30 knots over the Gulf, and some of the models predict this shear will remain over the Gulf over the next 7 - 10 days. However, other models predict that this band of high shear will retreat northwards and leave the Gulf nearly shear-free. The long-term fate of 93L remains very murky. My main concerns at this point are the potential for 3 - 6 inches of rain in Haiti over the next two days, and the possibility 93L could become a hurricane in the Gulf of Mexico next week.

Elsewhere in the tropics
None of the reliable computer models is calling for tropical cyclone formation elsewhere in the Atlantic over the next seven days.

Floods in China and Burma kill over 250
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 250 lives. The heavy rains and floods ravaging 10 southern Chinese provinces had killed 199 and left 123 missing as of 11:00 a.m. Tuesday, a Ministry of Civil Affairs statement said. Damage is estimated at $6.2 billion. Floods and landslides in neighboring areas of Myanmar (Burma) have claimed at least 63 lives in the past week.


Figure 2. Paramilitary policemen help evacuate residents from Wanjia village of Fuzhou City, East China's Jiangxi province, June 22, 2010. Days of heavy rain burst the Changkai Dike of Fu River on June 21, threatening the lives of 145,000 local people. Local authorities have ordered immediate evacuation, and the army and paramilitary police have begun conducting rescue operations. Image credit: Xinhua.

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 Saturday, 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, and will depend upon what 93L does.

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

"Hurricane Haven" airing again this afternoon
Tune into another airing of my live Internet radio show, "Hurricane Haven", at 4pm EDT today. Listeners will be able to call in and ask questions. The call in number is 415-983-2634, or you can post a question in the comments area on my blog. You can also email the questions to me today before the show: jmasters@wunderground.com. Be sure to include "Hurricane Haven question" in the subject line. Some topics I'll cover today on the show:

1) The latest on 93L
2) Which model is the most reliable?

Today's show will be 30 - 40 minutes, and you can tune in at http://www.wunderground.com/wxradio/wubroadcast.h tml. The show will be recorded and stored as a podcast.

Jeff Masters

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wasps!!! be careful, Pat!!!!!
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Quoting JFVfromFlorida:
we ar eofficially doomed cat 5 might hit florida.


ok should i ban him.
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This Season on NOLA Wasp Wars Uptown

Yellow Jackets 2

Patrap 0
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Quoting watchingnva:


flipping out like that is one of the easiest ways you get yourself not seen on here, ignored, minimized...pipe it down a bit...you will not convince everyone on this blog of your opinion, whether it be right or wrong. state your opinion and move on...


afternoon watch, already scorching hot out!
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i wana tell you i hope miy house isn't destroyed.

you mean your outhouse?
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Quoting IKE:


Haiti is sandwiched in with 93L. I notice increasing convection on the north side of Hispaniola.


Yup; both of their short term fates appear to be intertwined at the moment....
Member Since: August 8, 2006 Posts: 0 Comments: 9132
Quoting unf97:


Thanks! That what I was thinking that the system as a whole is still generally on a W/NW motion.


However, I just peeked at satellite imagery, and to me, it is beginning to look like a LLC is trying to come together now.



Looking a little more stormish down there, that I'll agree with.
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Quoting sailingallover:

That is NOT a COC...there is no COC, Center, LLC!!
That is vorticity which is most simply a value for air flow that is not straight over some area. It does not always mean there is a Circulation it means there is a change in Direction!!
The math is here is you want to dig through it
http://www.cimms.ou.edu/~doswell/vorticity/vorticity_primer.html


flipping out like that is one of the easiest ways you get yourself not seen on here, ignored, minimized...pipe it down a bit...you will not convince everyone on this blog of your opinion, whether it be right or wrong. state your opinion and move on...
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oops.
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Goodnight all, getting to cold for me.

Currently at Homebush, Sydney, Australia.

Temperature 52.0°F falling
Dew Point 49.1°F falling
Feels Like 52.0°F
Relative Humidity 90%
Wind
Wind Gusts -
Pressure -
Fire Danger -
Rain since 9am/last hr 0.0mm / -
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484. unf97
Quoting Hurricanes12:


I heard it shifted NW, but then I also hear it is still moving WNW.


93L as a system is still generally moving W/NW. Until a defined LLC develops, then we can decipher and pinpoint the exact motion.
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12z Early Cycle NHC model tracks
Invest93
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)





Dynamic Models (More sophisticated models)





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Quoting Hurricanes12:


I heard it shifted NW, but then I also hear it is still moving WNW.

That I believe is the MLC. The COC should develop to the Southwest of the main thunderstorm complex.
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Quoting KEEPEROFTHEGATE:


THERE ARE NO EVACS PLANNED FOR ANYWHERE IN THE ATLANTIC BASIN AT THIS TIME

No Active Tropical Warnings in the Atlantic, Caribbean, or Gulf of Mexico

As of Tue 22 Jun 2010 16:30:02Z

Action: Quote | Ignore User



love it.
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RGB Loop shows 93L still has plenty of work to do... but not as much as I thought earlier.

Shortwave shows organization may be getting a bit better.
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479. IKE
Quoting weathermanwannabe:
Unfortunately, Haiti is starting to get flooded as we speak......


Haiti is sandwiched in with 93L. I notice increasing convection on the north side of Hispaniola.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
If the center is at 17N 73W, 93L is better off. That's much closer to being right under the anticyclone.
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JFVfromFlorida


??????!!!!!!!!!!
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Quoting CaneWarning:


That's odd, I've had a ton of wasps and no ants this year.

I've had a ton of wasps & ants. the ants were nesting right inside my sister's window seal, luckily i had ORTHO MAX, they died instantly. As far as the wasps it was like a mass outbreak.
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473. IKE
Quoting nrtiwlnvragn:


Here is the Link to follow along.


189 hours




Thanks. That's in line with the ECMWF.

Interesting that it shows 93L and then the trough/cold front I mentioned, may pick it up.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting JFVfromFlorida:
hurricane 12 i think 60% it goes to florida bu 40% it miss it all togethar


I heard it shifted NW, but then I also hear it is still moving WNW.
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One of Brisbane's driest Junes on record... or so it seems


Brisbane and surrounds have had a very dry June so far, despite a few days of showery onshore winds.

The Queensland capital has collected just 0.4 mm in the month to date, a woeful figure when compared to the official June average of 62 mm. At this stage, this means that Brisbane is having it's driest June on record.

But the lack of rain has not been restricted to Brisbane alone. Both the Sunshine Coast and the Gold Coast have seen a rainfall deficiency, with most locations picking up less than 10 percent of expected monthly rainfall.

Maroochydore has so far recorded 13 mm, the driest June in at least 15 years.

Southeast QLD dams haven't scored too well either. Somerset has only picked up 14 mm in the last three weeks, less than a quarter of the average. However, overall the dam levels are hovering around 95 percent capacity, thanks to a fantastic boost earlier on in the year.

It's not all bad news. June is historically one of the drier months of the year for southeast Queensland, so we shouldn't expect much anyway. Thankfully though, more showers are on the way over the next few days.

© Weatherzone 2010
______________________________________________________________________________________________
I wish a certain 3 letter person would stop reinventing themselves or other people stop taking on there name. It's giving me the irrits.
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Quoting all4hurricanes:
93L keeps getting worse and worse. I don't care that conditions are ideal this blob has never shown signs of organizing or developing.


Just trying to stir up trouble.
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Quoting scottsvb:


Um.. where you get this map.. for 144hrs out.. I have nothing like this


Link in post #454
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Quoting JFVfromFlorida:
But i got to say 93l mieght be a big disaster waieitng to occur late in weak.


You do a poor job of pretending to be you know who.
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.
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Quoting mtyweatherfan90:
Good day to everyone, the cmc run shows two tropical systems, one passing through the caribbean and the Yucatan Peninsula moving then northward toward the Oil Spill zone. Followed by another system moving through Cuba and Florida curving to the north following a similar route. This would create some serious problems in that area REALLY too early in the season. And a third system hanging around just east of the Bahamas.





Link
The Canadian GEM model shows almost the same thing.Link
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Unfortunately, Haiti is starting to get flooded as we speak......
Member Since: August 8, 2006 Posts: 0 Comments: 9132
462. 606
Good Afternoon folks. What is this large circulation I see in the Mid Atlantic
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Quoting nrtiwlnvragn:


New GFS says.... maybe





Um.. where you get this map.. for 144hrs out.. I have nothing like this
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Lah,la..la
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Is there talk about it coming to Florida?
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457. MahFL
I see the coc at 71w 17N
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455. unf97
Quoting CyclonicVoyage:


No LLC yet. The whole package is moving WNW with a few embedded circulations, nothing organized though.


Thanks! That what I was thinking that the system as a whole is still generally on a W/NW motion.


However, I just peeked at satellite imagery, and to me, it is beginning to look like a LLC is trying to come together now.
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Quoting IKE:


You're posting the newer GFS...interesting.

The one I'm looking at doesn't show much at 144 hours.


Here is the Link to follow along.


180 hours


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Quoting RecordSeason:
"center" 73W 15.5N

This is the dominant low. The convection near Hispaniola is already being yanked around.
73? Not 71?
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Quoting unf97:
Good day everyone!

93L is very slowly organizing in the East Central Carribean Sea. I just signed in and I read a post stating motion is now NW. Has this motion been confirmed?

I think that is the convection to the Northeast of the actually Center, but really I'm not sure if it has a defined center to track. I've noticed how yesterday the convection was mostly east then west and now east. This storm is frustrating me. And I don't know what is holding it back from developing further?
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451. IKE
Looks like a front/trough, moves through the SE USA in about a week, according to the GFS I'm looking at.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting leo305:
shear is going to become a problem if the northern circulation takes over
I agree.
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Quoting KEEPEROFTHEGATE:


THERE ARE NO EVACS PLANNED FOR ANYWHERE IN THE ATLANTIC BASIN AT THIS TIME

No Active Tropical Warnings in the Atlantic, Caribbean, or Gulf of Mexico

As of Tue 22 Jun 2010 16:30:02Z


LOL love the banner!
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Quoting Hokie76:
Here in Palm Harbor (Fla.), during the active '04 and '05 hurricane seasons, we had no wasps and lots of ants and anoles. For the past 3 years, we had just the reverse. This year--like '04/'05--haven't seen a single wasp and ant hills and anoles are everywhere.


That's odd, I've had a ton of wasps and no ants this year.
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Quoting Hokie76:
Here in Palm Harbor (Fla.), during the active '04 and '05 hurricane seasons, we had no wasps and lots of ants and anoles. For the past 3 years, we had just the reverse. This year--like '04/'05--haven't seen a single wasp and ant hills and anoles are everywhere.
Plenty of wasps 15 miles to your east :)
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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.