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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Quoting RobertM320:


True, but it'se easier to clean their beaches than our marshes.


I don't think we need to get into a philosophical conversation about who's shoreline is easier to clean or who would feel the greater economic impact. Any storm that gets anywhere near the DWH is gonna wreak havoc on the entire Gulf. Even just a weak TS.
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Quoting CaicosRetiredSailor:
Try this again near the top of one of these fast flying pages...



Quoting smmcdavid:
Good morning all!... Can anyone give me any quick, useful updates on our invest of choice for the week? Thanks...




NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL

AMZ089-231530-
SYNOPSIS FOR CARIBBEAN SEA AND TROPICAL N ATLC FROM 07N TO 22N
BETWEEN 55W AND 65W
530 AM EDT WED JUN 23 2010
.SYNOPSIS...A TROPICAL WAVE ALONG 74W WILL MOVE W REACHING THE
YUCATAN PENINSULA LATE FRI NIGHT. LOW PRES MAY DEVELOP ALONG THE
WAVE LATER IN THE PERIOD. THE NEXT TROPICAL WAVE IS OVER THE
FAR E CARIBBEAN ALONG 63W. THIS WAVE WILL MOVER NW OVER THE NEXT
FEW DAYS.


(...or one could read back here for ten pages)

Good Morning
CRS


Thanks! I'm trying to keep up... but I'm having to do a lot of clean up today. Sick kids are no fun. :(
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3643. 34chip
At the moment Key West and the Florida Keys sure watch this system!
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they dd not cancelled the recon buy moved it to a later date
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morning fellow wunderbloggers!!!!,gfdl track looks solid,though its been bending slowly north and east more and more on each run,the plot looks feasable to me imo......
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Quoting StormW:
Just got off the phone with the NHC, CARCAH...Recon HAS been canceled today and is on for tomorrow.


Hi Storm, I get more than enough recon from this blog as it is. Don't you?
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3635. gator23
Quoting btwntx08:

???????????????

what is confusing you>?
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3634. Walshy
Received email recon was canceled today...
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Quoting StormW:
Just got off the phone with the NHC, CARCAH...Recon HAS been canceled today and is on for tomorrow.
Thanks Storm as usual the voice of reason
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3632. Patrap
A note on the BOP..it continues to List 11-12 degrees from the vertical.
Member Since: July 3, 2005 Posts: 421 Comments: 127664
How are y'all doing today?
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3630. bjdsrq
Quoting Jeff9641:


Plus where the models have this intialized there is nothing there.


Surely. Only where there is convergence of the models is *any* hint of confidence in track. Beyond 60 hours, forget it at this point.
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3629. aquak9
Quoting weatherman566:


You are right on the money. But then again, dispersion would help thin out the oil across the Gulf. But regardless, I would hate oil to be trapped into the Gulf Loop Current.


Wrong. Storm in Gulf means all relief-well work stops. Suction stops. ROV's leave. And it goes back to spewing like crazy.

Whatever gets dispersed at the surface will be replaced ten-fold at the leak.
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Quoting btwntx08:
its not forming at 72w and no its not headed to fl period


apparently the nhc disagrees with you (about the 72 part, as to where its going, who knows)...lol...wheres the orange circle centered? ... 23/1145 UTC 16.7N 72.6W TOO WEAK 93L...

we will see...honestly....i think these coordinates are close actually...since that's what they are saying...i also think we are getting a feeder band developing in the area to the southwest and also to the northeast...will see as the day goes...lol...

i still haven't fully woke up yet...lol...
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3627. bappit
Computer programs make assumptions about their data. The data could be as accurate as reasonably possible, but if the assumptions are incorrect then for the purposes of that program it is, to use a colorful term, garbage. Garbage in, garbage out.

Sophisticated does not necessarily mean better.
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Pat, ya'll still getting good shrimp in NOLA? We're getting plenty in Mobile.
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3624. Patrap
RECON was cancelled ..
Member Since: July 3, 2005 Posts: 421 Comments: 127664
Thanks, Storm!
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.
Member Since: September 23, 2005 Posts: 14 Comments: 10922
what's the deal with the big blob behind 93L? is that going to develop?
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Quoting btwntx08:

yes im sure and if models are indeed correct this is a la storm


And have you ever seen models nail the exact location before a storm develops? Everyone from Mexico to Florida needs to keep an eye on the situation until we actually get a closed low and some more reliable model results and that's not likely to occur for a few days.
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3616. gator23
Quoting clwstmchasr:


I don't thing Joe B. said the Fl Panhandle. I think he said further east. Many of the models want to take this to Texas. The ECMWF takes the system over LA.

Right the models mean nothing without a LLC especially this far out.
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Latest ASCAT. Missed most of the AOI but
being from 0300AM IF a low level circulation had formed SSE of Jamaica yesterday afternoon some curvature should be in the wind flow south of Jamaica now.. but nada..
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3614. Patrap
The Models reflect what may occur as to the envelopes future downstream, To say there is no LLC is moot as the energy is there .

Or the invest wouldnt be under scrutiny.

Relax..

Have a Dr. Peppa.

The My yard,my State thing is as stale as week old french toast.
Member Since: July 3, 2005 Posts: 421 Comments: 127664
Repost
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3612. bjdsrq
Quoting StormSurgeon:


I would hope you're right, but I still think it would be a mess.


I agree. Better for a surge to push all this sludge and oil a few blocks inland than to keep it in the sea killing off innocent and vitial sea life. Oil addicted humans caused it, let them clean it up from their backyards. It will get done faster and easier that way.
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I am very sorry they have changed the flight plan the flight plan as follows

000
NOUS42 KNHC 231345
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
0945 AM EDT WED 23 JUNE 2010
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 24/1100Z TO 25/1100Z JUNE 2010
TCPOD NUMBER.....10-023

I. ATLANTIC REQUIREMENTS
1. SUSPECT AREA (SOUTHWEST OF JAMAICA)
FLIGHT ONE - TEAL 70
A. 24/1800Z
B. AFXXX 01AAA INVEST
C. 24/1330Z
D. 16.5N 80.0W
E. 24/1700Z TO 24/2100Z
F. SFC TO 10,000 FT

FLIGHT TWO - TEAL 71
A. 25/0600Z
B. AFXXX 0201A CYCLONE
C. 25/0200Z
D. 17.0N 81.0W
E. 25/0400Z TO 25/0830Z
F. SFC TO 10,000 FT

2. SUCCEEDING DAY OUTLOOK: CONTINUE 12 HRLY
FIXES IF SYSTEM REMAINS A THREAT.
3. REMARKS: TASKING FOR 23/1800Z AND 24/0600Z
CANCELED BY NHC AT 23/0930Z.

II. PACIFIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.
JWP


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Jeff, don't forget about an increased tornado threat here either.
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Looks at 93L, Nuttin, logs off, come back tomm
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Try this again near the top of one of these fast flying pages...



Quoting smmcdavid:
Good morning all!... Can anyone give me any quick, useful updates on our invest of choice for the week? Thanks...




NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL

AMZ089-231530-
SYNOPSIS FOR CARIBBEAN SEA AND TROPICAL N ATLC FROM 07N TO 22N
BETWEEN 55W AND 65W
530 AM EDT WED JUN 23 2010
.SYNOPSIS...A TROPICAL WAVE ALONG 74W WILL MOVE W REACHING THE
YUCATAN PENINSULA LATE FRI NIGHT. LOW PRES MAY DEVELOP ALONG THE
WAVE LATER IN THE PERIOD. THE NEXT TROPICAL WAVE IS OVER THE
FAR E CARIBBEAN ALONG 63W. THIS WAVE WILL MOVER NW OVER THE NEXT
FEW DAYS.


(...or one could read back here for ten pages)

Good Morning
CRS
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Shear is increasing between the Yucatan and Cuba I think this slows down development as we seen before last season and so far this season larger cloud tops want to go north while surface level winds push everything westward.
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Quoting StormSurgeon:


I'm all messed up, I thought the panhandle was in Texas......LOL. Go Gamecocks!


there is a texas panhandle and Florida panhandle. the texas panhandle is the very top north square.

the florida panhandle is the northern rectangle (NOT the landmass that dips south). i remember thinking when i was younger that both areas of florida look like panhandles, really.
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3604. gator23
Quoting Jeff9641:


So everybody including JB is wrong. Why don't you think this is going to the Panhandle when a huge trough will be digging across the east this weekend.

you are correct Jeff, not to mention that the BIG BEND of Florida isnt safe either. He belives the models are worth a lick, the models are crap without a well defined LLC.
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3602. Patrap
Rainbow Still

Member Since: July 3, 2005 Posts: 421 Comments: 127664
3600. IKE
Quoting nrtiwlnvragn:
Models spreading apart




Interesting.

And some take it along the northern and NE GOM...aka Florida panhandle.

Quoting Chicklit:

Ref Post 3565:
They may change coordinates, but I would be surprised if they don't go out today, particularly since Dr. Masters has said the HH flights would be a record number this year due to a study on rapid intensification.


I'm going by what a couple of posters said. One said the TWC said it was canceled for today.

Maybe it's still on. If not, I'm sure they'll reschedule for Thursday.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Recon is canceled, didn't read the text.
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Quoting Jeff9641:


So everybody including JB is wrong. Why don't you think this is going to the Panhandle when a huge trough will be digging across the east this weekend.


Wishcasting is ever-present as we both know.
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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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