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 srada:


Yeah but Ernesto found a way back after the mountains..this is not a far fetched scenario and it has happen before..
I don't find an Ernesto scenario likely for the time being.
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Quoting StormW:
Hanna!!


Storm!!!!! Getting busy already eh?
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Quoting Jeff9641:
Just as I've been saying all day the models would shift east due to the massive trough building in. This is a Florida storm with the potential of a big hurricane. People need to look more at the upper air patterns than models. Upper air pattern don't lie guys.


First of all troughs dig and ridges build - second you are Sir gloom and doom, between late afternoon sea breeze storms that dump 10 inches of rain to an invest that will become a major cane and hit Florida - c'mon man, give it a rest.
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Quoting extreme236:
AL, 93, 2010062300, , BEST, 0, 156N, 752W, 25, 1010, WV
YES! I won my bet. That's exactly where I placed it.
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2241. NASA101
Quoting Jeff9641:
Just as I've been saying all day the models would shift east due to the massive trough building in. This is a Florida storm with the potential of a big hurricane. People need to look more at the upper air patterns than models. Upper air pattern don't lie guys.



HAHA, Wishcating! This is not even close to a TD yet!
In my opinion, the longer it takes to develop the more West it goes!
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Quoting extreme236:
EP, 05, 2010062300, , BEST, 0, 108N, 930W, 30, 1006, TD
Where do you get that info from? Include the link, please. Thanks!
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Hey Pat, Storm. I'll bet you two have been pretty busy monitoring things
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2238. Patrap
The Gulf Coast is experiencing some weather from a Low inland interacting with a Tropical Wave




473
fxus64 klix 221849
afdlix


Area forecast discussion
National Weather Service New Orleans la
149 PM CDT Tuesday Jun 22 2010


Short term...(tonight-thursday)...inverted trough off the coast of
Louisiana with associated upper level disturbance creating enough
convergence with ample deep layer moisture available for numerous
showers/isolated thunderstorms across the coastal waters. Earlier
today this activity was having a hard time penetrating inland...but
with surface heating early this afternoon expect coverage &
intensity of convection to increase over land areas. The main
threats will be locally heavy rainfall...frequent lightning in a few
storms and downburst winds 40 to 50 miles per hour in stronger cells. Expect
activity to wind down later this evening but will still carry a
20%-30% pop overnight for lingering convection.


This system will be slow to exit the area overnight/Wednesday moving
east to west and will provide a high end scattered chance of
precipitation again on Wednesday as we will have a deep fetch of
onshore flow...though afternoon maximum temperatures are forecast to
recover a couple/few degrees higher than highs realized today across
most areas. Pop chances will decrease to 20%-30% on Thursday as the
upper level system migrates further away from the area taking deeper
layer moisture with it. Highest pop chances on this day will reside
across the west.


Long term...(thursday night-tuesday)...deep layer ridging will
reinforce its will over the region until Saturday as it gradually
migrates further northeastward. This will allow for the return of
onshore flow with deep moisture return to the area Mon-Tue.
Parameters will warrant a 20%-30% pop mention in the forecast Friday-
sun with a return to 40% Mon-Tue. Highest chances will be south of
the Interstate 10 corridor. Temperatures are forecast slightly
above climatology with afternoon highs maxing out into the Lower/Middle
90s.
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Quoting Jeff9641:
Just as I've been saying all day the models would shift east due to the massive trough building in. This is a Florida storm with the potential of a big hurricane. People need to look more at the upper air patterns than models. Upper air pattern don't lie guys.
Florida? I don't see the trough being so far east and so strong to push the system towards Florida. A Louisiana event seems the most likely for the time being, but we all know how quickly that could change.
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2235. nolajet
Quoting Drakoen:


Yea the consensus is pointing at Louisiana


Isn't that usually a good thing this far out though, as the models generally shift on way or the other?

And no, that would not be good at all. :\

*Edit - And welcome back Hannah, good to see you here again this season. :)
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Quoting StormW:


I haven't checked buoy data yet, but everything appears to be mid to upper...besides, it'll be inland in the next 24-36 hours.


That's exactly what Humberto said, yes? ;)
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2233. srada
Quoting weatherwatcher12:

If it reaches there without going through the gulf it would most likely get torn apart by the mountains of Cuba before it can reach.


Yeah but Ernesto found a way back after the mountains..this is not a far fetched scenario and it has happen before..
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2232. Patrap
00z Early Cycle NHC model tracks
Invest93
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)





Dynamic Models (More sophisticated models)



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Hey Alaina!!! I really worry what will happen this year.
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Let's put this to rest. Drak, Storm, Adrian, Levi%u2026If 93L does develop, do you see any scenario in which it would affect so. Florida? And I know nothing is set in stone this far out. Just asking what they see now.
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Quoting taco2me61:
Welcome Back Hanna I have to tell you this does not look good for anyone on the Gulf Coast.....

Taco :o)

Hey Taco! Yeah, things just don't look good at all.
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2226. Drakoen
Quoting IKE:


Wow...big shift...oil volcano...storm...not good.


Yea the consensus is pointing at Louisiana
Member Since: October 28, 2006 Posts: 57 Comments: 30562
Quoting hurricanehanna:
Hello to everyone. One of my first times posting this season...too busy watching the oil spill mess off of our coast. We always say we don't need a storm...but this year, it would do more damage than the norm. I can't fathom what would happen if that oil comes further inland.

Hey Hanna!
Good to see you back. And yes I agree with your post. Even more at stake this season.
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Quoting MiamiHurricanes09:
Too bad that that ASCAT is much older than the time that the surface circulation developed. By the way it is 16 hours old, I don't consider that to be "new".

10 hours old...
We can wait until tomorrows post and see if a circulation has developed as of now...
Theres upper level rotation for sure and some lower level vorticity but nothing I'd count as a circulation
I'll cook a crow...
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Quoting BayouBorn1965:
Truecajun, people will be people, good and bad. Personally, we keep up our hurricane stash all year long. Katrina taught us many lessons the hard way, especially about how there will be others around you that will need for you to share your supplies, and that is exactly what we did and will continue to do when the next big one blows us away. :)

Agree!
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Quoting hurricanehanna:
Hello to everyone. One of my first times posting this season...too busy watching the oil spill mess off of our coast. We always say we don't need a storm...but this year, it would do more damage than the norm. I can't fathom what would happen if that oil comes further inland.
Welcome Back Hanna I have to tell you this does not look good for anyone on the Gulf Coast.....

Taco :o)
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Quoting StormW:


I really don;t see any worry with it. There is a large Upper Low that is gonna eat it.


Eat it over land?

I do not want to come off sounding like an alarmist here, but I just looked at every satellite image of that area over the past 12 hours and it seems that a low is wanting to form south of Houma, LA at this hour. There is circulation from what I am seeing.
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2218. IKE
Quoting nrtiwlnvragn:


Wow...big shift...oil volcano...storm...not good.
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Notice the low shear, the low system speed, warm SSTs, and extreme heat content.

* ATLANTIC SHIPS INTENSITY FORECAST *
* GOES DATA AVAILABLE *
* OHC DATA AVAILABLE *
* INVEST AL932010 06/23/10 00 UTC *


TIME (HR) 0 6 12 18 24 36 48 60 72 84 96 108 120
V (KT) NO LAND 25 26 29 32 36 43 54 64 71 76 84 88 92
V (KT) LAND 25 26 29 32 36 43 54 64 71 76 84 69 58
V (KT) LGE mod 25 26 27 28 30 36 44 56 71 89 102 84 67

SHEAR (KT) 6 5 8 7 5 10 5 10 0 9 3 12 1
SHEAR ADJ (KT) 0 0 -2 -3 0 -2 -6 -4 -3 -4 -1 0 -2
SHEAR DIR 224 244 310 329 316 347 13 22 81 20 64 21 244
SST (C) 28.9 28.9 29.0 29.1 29.1 29.2 29.3 29.3 29.6 29.5 28.8 28.3 28.1
POT. INT. (KT) 150 150 151 153 153 154 155 155 161 159 147 139 136
ADJ. POT. INT. 146 145 145 146 144 143 144 144 149 145 133 125 122
200 MB T (C) -52.3 -52.4 -52.6 -52.3 -52.0 -52.3 -51.9 -52.3 -51.8 -52.2 -51.7 -52.3 -51.9
TH_E DEV (C) 8 8 8 10 10 9 11 9 12 9 13 10 13
700-500 MB RH 79 80 76 73 72 71 68 71 69 72 69 65 59
GFS VTEX (KT) 7 7 7 7 7 7 7 8 7 6 7 5 4
850 MB ENV VOR 91 95 83 81 81 75 75 65 61 56 47 20 22
200 MB DIV 59 51 41 38 24 1 12 8 11 13 10 -4 16
LAND (KM) 266 216 178 162 182 263 320 265 296 216 89 -34 29
LAT (DEG N) 15.6 15.9 16.1 16.4 16.7 17.1 17.5 17.9 18.5 19.2 20.0 20.8 21.8
LONG(DEG W) 75.2 76.3 77.3 78.2 79.0 80.5 81.7 83.0 84.3 85.4 86.5 87.4 88.3
STM SPEED (KT) 11 10 9 9 8 7 7 7 7 6 6 6 6
HEAT CONTENT 74 78 90 106 119 77 108 101 105 102 82 42 0

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Quoting srada:
I really dont feel 93L is a GOM event..watch out florida and the east coast

If it reaches there without going through the gulf it would most likely get torn apart by the mountains of Cuba before it can reach.
Member Since: May 16, 2009 Posts: 1 Comments: 1231
Hello to everyone. One of my first times posting this season...too busy watching the oil spill mess off of our coast. We always say we don't need a storm...but this year, it would do more damage than the norm. I can't fathom what would happen if that oil comes further inland.
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Member Since: September 23, 2005 Posts: 14 Comments: 11215
2213. xcool
. srada byebye
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Quoting Drakoen:
BAMM have it crawling.. 7-6 knots in the Western Caribbean and into the GOM..


This will cause a more northerly track--not good for good for the eastern GOM.
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2210. JRRP
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Blog Update!

June 22, 2010 - 8:35 PM EDT - 93L -
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Quoting Drakoen:
BAMM have it crawling.. 7-6 knots in the Western Caribbean and into the GOM..
That is scary considering the prime conditions it should have when it gets there.
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2205. Drakoen
BAMM have it crawling.. 7-6 knots in the Western Caribbean and into the GOM..
Member Since: October 28, 2006 Posts: 57 Comments: 30562
Quoting ezcColony:


I would have preferred you have said, "It won't."

It wont.
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Quoting Fluid:


The reality is that in any population of people, and especially so in cities, you are going to have a certain percentage that can not take the action necessary, for any number of reasons. They may be ill, they may have mobility problems, they may have cognitive problems, they may simply have no money, or they may be somehow tied so that they feel that they can't (threatened with loss of job, fearful of loss of pets, or home) or shouldn't (be in a helping profession and remain behind), may have intended to but was thwarted at the last minute (car breaks down, someone has an unrelated un-expected medical event, can't locate a family member) etc etc etc.

Yes, you can say "Hell with 'em!" , but once you cross that line, your society will inevitably decay into something that reflects that attitude through out all its behavior.

I agree. It makes me so mad when people say the hell with them idiots get what they deserve. UGH!!! For many reasons as you pointed out some can't leave. A lot have said the rescuers shouldnt have to rescue people after a storm since they decided to stay. Well at what point should the rescuer ask his/herself is this an idiot who just didn't want to leave? Or is this someone who deserves being rescued? Should they ask themselves while they're hanging in midair from a helicopter? Sorry for the rant.
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check out the 18z runs -gfdl and hwrf for the pacific storms. then click on the last pic. there in the usa side one can see the steering currents for 93. it looks like gfdl has the trof digging in later, hence a n course...while the hrwf already has the trof getting to the east coast which might suggest a strong turn to the ne at the last moment(like maybe ala/fla).so the question might be is where the trof is located the last 24 hrs before landfall.
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Quoting extreme236:
AL, 93, 2010062300, , BEST, 0, 156N, 752W, 25, 1010, WV
Agree with the longitude, disagree with the latitude.
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2197. IKE
Quoting weatherfan92:

Where is a link to this HWRF track?
Link

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AL, 93, 2010062300, , BEST, 0, 156N, 752W, 25, 1010, WV
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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.