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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1196. ssmate
No reason trying anymore on SST, We've peaked. But we will set records.
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93L is spinning now.. but gonna clip Haiti. anything will be slow. Katrina was just a depression sitting in the bahamas at one point though
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1194. shauntanner (Admin)
Listen to the Weather Underground Broadcast Network here

http://www.wunderground.com/wxradio/wubroadcast.html
Deja Vu all over again. like 2009 all over again, aint a damn thing matererializing
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Quoting Chigz:
93L is not even close to a TD, and yet people, or shall I say wishcasters are hanging their hopes on some trough coming down or high pressure building in 5-6 days time! Just too funny..
I have no faith in intensity models this far out - no way!
An upper level ridge it just prone to develop with the weak easterly winds and all the heat out there.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
New map I made concerning the potential future of 93L.. I still feel the LLC forms south of the forecast point.

Map made based on the maps and pattern

Photobucket
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Quoting GeoffreyWPB:
I thought for sure yesterday 93L would be close to depression status by now. Looking like it may take a few more days.
Yeah, haven't been expecting development so rapidly, might take another couple days to take off, still has to work on some things.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
1189. ssmate
He's pro 93L!!
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1188. KEEPEROFTHEGATE (Mod)


977

WHXX01 KWBC 221923

CHGHUR

TROPICAL CYCLONE GUIDANCE MESSAGE

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL

1923 UTC TUE JUN 22 2010



DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.

PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE

AND SUBTROPICAL CYCLONE INFORMATION.



ATLANTIC OBJECTIVE AIDS FOR



DISTURBANCE INVEST (AL932010) 20100622 1800 UTC



...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...

100622 1800 100623 0600 100623 1800 100624 0600



LAT LON LAT LON LAT LON LAT LON

BAMS 15.5N 74.4W 16.1N 76.6W 16.9N 78.7W 17.4N 80.6W

BAMD 15.5N 74.4W 16.1N 76.3W 16.5N 78.1W 16.7N 79.6W

BAMM 15.5N 74.4W 16.0N 76.5W 16.6N 78.5W 17.0N 80.1W

LBAR 15.5N 74.4W 16.1N 76.8W 16.9N 79.3W 17.5N 81.6W

SHIP 25KTS 28KTS 35KTS 42KTS

DSHP 25KTS 28KTS 35KTS 42KTS



...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...

100624 1800 100625 1800 100626 1800 100627 1800



LAT LON LAT LON LAT LON LAT LON

BAMS 18.0N 82.5W 18.9N 85.6W 19.9N 88.3W 21.2N 90.9W

BAMD 16.8N 81.0W 17.1N 84.1W 17.6N 87.1W 18.1N 90.1W

BAMM 17.2N 81.6W 17.8N 84.4W 18.6N 87.1W 19.6N 89.8W

LBAR 18.1N 83.9W 19.8N 88.0W 21.5N 91.1W 22.6N 92.7W

SHIP 52KTS 71KTS 86KTS 96KTS

DSHP 52KTS 71KTS 86KTS 36KTS



...INITIAL CONDITIONS...

LATCUR = 15.5N LONCUR = 74.4W DIRCUR = 280DEG SPDCUR = 14KT

LATM12 = 15.1N LONM12 = 71.5W DIRM12 = 279DEG SPDM12 = 14KT

LATM24 = 14.5N LONM24 = 68.8W

WNDCUR = 25KT RMAXWD = 60NM WNDM12 = 25KT

CENPRS = 1010MB OUTPRS = 1011MB OUTRAD = 120NM SDEPTH = S

RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM



$$

NNNN
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Quoting frostynugs:
"We didn't stop flying airplanes for six months after 9/11, did we?"

Planes didn't keep crashing into buildings for 2 months after 9/11, did they? They weren't still crashing into buildings every day when they ban on flight was lifted, were they?


And that's easy to say in hindsight. Would you have guaranteed that on September 21, 2001? I doubt it. And its been two months and I haven't seen any other rigs explode either. Again, you punish everyone for one companies mistake. Heck, if you want, shut all of BP's rigs down.

Let's try this for example: If three different tourists got murdered on three different Florida beaches in one week, would you shut down all the beaches throughout the entire state until the murderers were caught? .... I didn't think so.
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I thought for sure yesterday 93L would be close to depression status by now. Looking like it may take a few more days.
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1183. ssmate
Here it comes.....
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There we go... :)
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Any chance 95E could play the Atlantic?
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frickin talking 101 in there,
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1178. IKE
Quoting RitaEvac:
wth, why arent we asking Jeff about 93L??


Exactly...lol.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
1177. xcool
btwntx08 so true. all about time.
Member Since: September 26, 2009 Posts: 2 Comments: 15626
wth, why arent we asking Jeff about 93L??
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Funny how the NHC lowers the probs. right when the low is finally forming.

Looks like a track between Jamaica an Cuba might take place IMO.

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Quoting IKE:


He didn't say. He just said it looked like it would/could be strong enough to turn 93L.


What about turning north with a bit of eastward movement?
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Quoting IKE:


He didn't say. He just said it looked like it would/could be strong enough to turn 93L.


also could be after hits land, then turns north for all we know
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1171. ssmate
Quoting IKE:


He didn't say. He just said it looked like it would/could be strong enough to turn 93L.

Said with conviction too, IMO
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Quoting IKE:


He didn't say. He just said it looked like it would/could be strong enough to turn 93L.
Oh ok, thanks.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
1169. WxLogic
Quoting Drakoen:
The NHC is absolutely correct when they lowered the chances within 48 hours. The system is really not what we have been monitoring south of the DR and Haiti. Probably just a mesoscale convective vortex. The area we need to focus on is between 75W-72W.


I can see that... new convection is starting to fire around that 850MB Vort max between 75W to 72W, but I have doubts about that area. I guess we'll see during DMAX tomorrow AM.
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Quoting Tazmanian:
looks like 93L now has a a spin too it we could see 93L take off


I definitely see an improved circulation on the visible loop.
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1167. IKE
Quoting staggalee:
It would have to get significantly stronger by then to turn north, no?


He didn't say that either. He just said what I posted above.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
LLC in the SE Caribbean seems to be getting sucked into the MLC, CMC was showing 2 systems a couple days ago?

Member Since: January 30, 2010 Posts: 0 Comments: 3259
It would have to get significantly stronger by then to turn north, no?
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1164. IKE
Quoting MiamiHurricanes09:
At what longitude degree should it turn towards the north?


He didn't say. He just said it looked like it would/could be strong enough to turn 93L.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting IKE:
Dr. Masters just said a trough in the east may in fact turn 93L north in about 5 days.
At what longitude degree should it turn towards the north?
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting quante:
This board is like slowing down for an accident. I know there is nothing to see, but yet I keep looking.


I know, i have been looking on here every 5 minutes all day today, lol, don't knwo what i want to see but still waiting!
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Quoting Floodman:


I understand the need for people to keep their jobs, truly I do...maybe the oil industry, whose focus has NEVER been on the safety of their people or the environment should be paying unemployment while someone other than the oil industry figures out if it's safe or not to drill at 5000 feet? I'm not even worried about whether it's "safe", per se, but I'd really like to know if another of these deep water wells goes we have some way to stop the damned thing in less than 6 months.

The funny thing here is that BP couldn't possibly have cared less about the fishermen that would be out of work when they made the decisions they did with no fall back position...I think a brief moratorium is the smart thing to do while we figure out if we're going to be looking at this mess all over again but a little further west next time...or east...I don't want anyone out of work, but try thinking about TWICE the oil in the water right now

As for the no fly after 911, it was 3 days for select flight, but 10 days before flight returned to "normal"...


..and I wouldn't want a second one either. Ten days, maybe two weeks of moratorium. long enough to create some guidelines, and again, there is NO RISK to drilling in rock. Remember, there was several days of warning signs prior to the explosion. Put someone on each rig, like the air marshals on the planes, to monitor, with full authority to halt drilling, and that should do. You can't shut them all down because of one crooked company.
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1159. IKE
Dr. Masters just said a trough in the east may in fact turn 93L north in about 5 days.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
hey Dr. Masters What are the possiblitys for the effects of 93L on the biggest of all three islands of the Cayman Islands, Grand Cayman and what will they be
Member Since: June 13, 2009 Posts: 2 Comments: 11233
Convection starting to increase some in the area around 18Z Best Track. This is going to be a slow process but it is starting to take shape. Don't expect it to get going for at least another 48hrs. It is not going to bloom until it gets into the GOM. It needs to get further W and the MLC to fizzle over DR.
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Once this thing gets past Jamaica, is when it should take off pretty quick.
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93L has been slowly organising it's vorticity into one dominant center over the past day while moving slowly W.

I predict tonight we will see the first convection start to consolidate around the center of rotation 74W 16N and we could get the first surface circulation developing during the course of wednesday.
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I hope you are right taz this is giving me a headache
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looks like 93L now has a a spin too it we could see 93L take off
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Unlike the 75W circulation, the one near Haiti has convection support.
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MX may be in for a rude a wakeing if 93L takes off
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Quoting wunderkidcayman:
I am seeing possible tracks near to 93L location curently to NHC position and what I think the track will be like

TS BONNIE 2004



HURRICANE CHARLEY 2004


HURRICANE IVAN


HURRICANE DENNIS 2005



HURRICANE EMILY 2005



HURRICANE WILMA 2005



TS BARRY



TS OLGA



and TS FAY and HURRICANE GUSTAV


roflmao
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To Dr.M~

When do YOU think the real season is going to start?

Mike P
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I am seeing possible tracks near to 93L location curently to NHC position and what I think the track will be like

TS BONNIE 2004



HURRICANE CHARLEY 2004


HURRICANE IVAN


HURRICANE DENNIS 2005



HURRICANE EMILY 2005



HURRICANE WILMA 2005



TS BARRY



TS OLGA



and TS FAY and HURRICANE GUSTAV
Member Since: June 13, 2009 Posts: 2 Comments: 11233
93L lacking organization after looking on satellite, but the circulation seems to be better defined as 850 millibar vorticity has tightened some and improved.
Member Since: September 2, 2009 Posts: 130 Comments: 21091

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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.