Potentially dangerous 92L steadily developing; Igor nears hurricane strength

By: Dr. Jeff Masters , 3:04 PM GMT on September 11, 2010

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A tropical disturbance (92L) over the Eastern Caribbean, a few hundred miles south of Puerto Rico, is steadily organizing and appears likely to develop into a tropical depression by tonight or Sunday morning. Satellite loops show an impressive and expanding region of heavy thunderstorms, with good spiral banding and respectable upper-level outflow on all sides. Long range radar out of Puerto Rico shows that heavy rains are now affecting that island, but there is no rotation to the radar echoes evident. However, the rain bands are becoming more intense and more organized. San Juan, Puerto Rico reported a heavy rain squall at 8:44 am this morning, and radar estimates suggest two inches of rain fell in this squall just southeast of San Juan. Wind shear over 92L is low, 5 - 10 knots. The waters beneath are at near-record warmth, 30°C, and these warm waters extend to great depth. Water vapor satellite loops show a large area of dry air lies to the north and west of 92L, and this dry air could interfere with development at times over the next few days.


Figure 1. Morning satellite image of 92L.

Track forecast for 92L
The disturbance is moving west-northwest at 11 mph, and steering currents favor a continuation of this motion for the next three days. Model support for development is scattered. The GFS and NOGAPS models do not develop 92L. The GFDL and ECMWF models predict development, with a track taking 92L into Mexico's Yucatan Peninsula on Wednesday. The HWRF model has a more northwesterly track, taking 92L over the Dominican Republic, Haiti, and Cuba, but this model has been trending too far north in its tracks. I expect 92L will follow a path south of the islands, bringing it near or just south of Jamaica on Monday, then into the Yucatan Peninsula on Wednesday. On this track, the southern Dominican Republic can expect heavy rains of 3 - 6 inches tonight through Monday morning; southern Haiti can expect similar rains Sunday through Monday, and Jamaica and the Cayman Islands can expect heavier rains of 4 - 8 inches Monday and Tuesday. Eastern Cuba will probably escape 92L's heaviest rains in this scenario (Figure 2.)

Intensity forecast for 92L
I can't find any reason to doubt this will be a tropical storm by Sunday or Monday, and potentially a Category 1 or 2 hurricane by Wednesday, if 92L avoids passage over Hispaniola and Cuba. The SHIPS model predicts wind shear will remain low, 5 - 10 knots, through the period, and makes 92L a Category 1 hurricane by Monday night. Water temperatures are certainly warm enough to support development. The main detriment to intensification is likely to be dry air, and 92L could wrap in some of the dry air to its northwest at times, slowing down development. The first Air Force Hurricane Hunter mission into 92L is scheduled for Sunday afternoon, but there will be a research mission by the National Center for Atmospheric Research G-V jet today that will give us valuable information on 92L's large scale environment and potential for development.


Figure 2. Forecast rain amounts from 92L from the 2am EDT Saturday run of the GFDL model. This model predicts most of 92L's heaviest rains will miss Haiti, but will affect Jamaica, the Cayman Islands, and the Yucatan Peninsula. Image credit: Morris Bender, NOAA/GFDL.

Igor
Tropical Storm Igor is very close to hurricane strength, and appears destined to become a large and powerful major hurricane over the Central Atlantic in the days to come. Wind shear is moderate, 15 - 20 knots, waters are warm, 28°C, and Igor has moistened its environment enough to keep the dry air of the Saharan Air Layer (SAL) at bay. Igor will track west under the influence of a strong ridge of high pressure for the next three days, then turn more to the west-northwest in response to the steering influence of a broad trough of low pressure moving across the Western Atlantic on Tuesday and Wednesday. This should allow Igor to pass several hundred miles to the northeast of the Lesser Antilles. In the longer range, Igor may be a threat to Bermuda, and has a slight chance of making landfall on the U.S. East Coast or Canada. Climatology shows that about 10% of all tropical cyclones that have existed at Igor's current position have gone on to hit the U.S. East Coast; these odds are about 10% for Bermuda and 5% for Canada. The forecast steering pattern for the coming two weeks from the GFS model shows a continuation of the pattern we've seen all hurricane season, with regular strong troughs of low pressure moving off the U.S. East Coast. This pattern favors Igor eventually recurving out to sea without affecting any land areas. The odds of Igor hitting land in the U.S. or Canada are probably close to their climatological 10% and 5% probabilities, respectively.

Elsewhere in the tropics
A new tropical wave (Invest 93L) emerged from the coast of Africa yesterday, and is already showing signs of organization. Most of the models predict 93L will develop into a tropical depression 2 - 4 days from now, and NHC is giving 93L a 30% chance of developing by Monday.

Next post
This may be my only post today; I'll have a new post Sunday morning.

Jeff Masters

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1073. JRRP
Quoting Neapolitan:
A repost from earlier for thos who may have missed it, here's a visual summary of the 2010 hurricane season so far:

Tropical weather-related image

lol
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1064 Neapolitan... Just Wonderful !!
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1071. Levi32
Igor looks like a hurricane now.

Quoting Relix:
So, pros, what's the probability of Igor affecting the northern leeward islands?

I keep it at 5% for now and less. Any takers? =P


Low, considering he's already up at the latitude of the northernmost islands, but they should watch for a possible side-swipe if a track like the 12z UKMET pans out.
Member Since: November 24, 2005 Posts: 635 Comments: 26654
Quoting Relix:
So, pros, what's the probability of Igor affecting the northern leeward islands?

I keep it at 5% for now and less. Any takers? =P


Less than 20%
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Quoting will40:


good cluster StormW

\
evening storm what are your thoughts on Igor this eve and what is your thaught on the models showing a potential greater threat to the us?
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Quoting Levi32:
Oh boy....the 500mb pattern over North America at Day 6 on the 12z UKMET is a big owwee in terms of Igor.

It has the polar vortex diving out of central Canada in such a way that would raise the heights to the east and take Igor farther west before recurving.



12z UKMET track is in blue with boxes:



Looks that away dont it?
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1067. Relix
So, pros, what's the probability of Igor affecting the northern leeward islands?

I keep it at 5% for now and less. Any takers? =P
Member Since: August 3, 2006 Posts: 0 Comments: 2725


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1065. IKE
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Quoting HurricaneSwirl:
5 named storms formed in September 2005.. Which I think we can actually beat. However the real show was in October for 2005, which was 2005's most active month with 7 named storms, including the infamous Wilma and the start of the Greek alphabet naming system.


We've already had 3 named storms this month (Gaston, Hermine, Igor.) Julia is likely to come tomorrow, which makes four. Then 92L will likely be named, and the wave behind 93L will need to be watched. Thats a potential total of 6 named storms by the end of this coming week.
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1062. Levi32
Quoting MoltenIce:
What's up with 92L continuously loosing and regaining convection? Storm, any thoughts?



Dry air/Subsidence.
Member Since: November 24, 2005 Posts: 635 Comments: 26654
Quoting TropicalAnalystwx13:
Earlier:



Now:



93L is really organizing especially convection-wise.
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What's up with 92L continuously loosing and regaining convection? Storm, any thoughts?

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1059. Levi32
Oh boy....the 500mb pattern over North America at Day 6 on the 12z UKMET is a big owwee in terms of Igor.

It has the polar vortex diving out of central Canada in such a way that would raise the heights to the east and take Igor farther west before recurving.



12z UKMET track is in blue with boxes:

Member Since: November 24, 2005 Posts: 635 Comments: 26654
5 named storms formed in September 2005.. Which I think we can actually beat. However the real show was in October for 2005, which was 2005's most active month with 7 named storms, including the infamous Wilma and the start of the Greek alphabet naming system.
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Earlier:



Now:

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Of all the island posters(hi!), I wonder how many are non-retiree's that are expats from the US. My wife and I dream of taking our talents, so to speak, to the islands. Life is short, you have to do what makes you happy.
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Quoting GTcooliebai:

If we were to get Karl and Julia tomorrow, we would only be behind by 1, & they're plenty more healthy looking waves coming off Africa.


If we somehow get Karl tomorrow, or 11-4-2 (Igor will be a hurricane at that time) it would be the most active hurricane season this early in since 2005.
Member Since: July 8, 2005 Posts: 259 Comments: 24185
1054. Grenada
This time in 2004 we in Grenada were wondering who dropped the bomb!
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1053. Dakster
Thankfully there will not be a Hurricane Romeo -- for Juliet to stick around for.
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Quoting TropicalAnalystwx13:
Post 1004:
Nice Grouping!
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Quoting TropicalAnalystwx13:
Wait...lol

We'll be 5 behind 2005 tomorrow.


Yeah I was just about to post that as well lol. 2005 was at Ophelia at this time, their 15th named storm, 6 named storms ahead of us.
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Wait...lol

We'll be 5 behind 2005 tomorrow. That's considering that we get Julia from either 92L/93L tomorrow.
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92L

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Quoting TropicalAnalystwx13:


I know. Needed to do more research :D

The post is fixed. We should tie 2008 tomorrow, and beat 2004. We should also be 2 behind 2005.


Yeah blog is moving too fast. Typed my post up and clicked post and you had already figured it out XD
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Quoting TexasHurricane:


yeah, 92L is saying y'all just wait. I got the GOM (hot tub) ahead of me. patience.....:)


The new storm development of 92l looks to be just forming, there are tee tiny storms starting to fire what appears to be the center
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Quoting HurricaneSwirl:


2008 had Josephine by September 2, so 2008 is ahead of us. However 2008 only had 4 storms in September which I think we can beat.


I know. Needed to do more research :D

The post is fixed. We should tie 2008 tomorrow, and beat 2004.
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1045. jonelu
NHC certainly got bullish on 93L...Maybe he will beat 92L and become Juliet first
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. (deleted post, blog is going too fast for me and by the time I posted there was no point lol)
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Quoting ackee:
guess the race is on between 93L And 92L for Julia seem right now 93L is in the lead



yeah, 92L is saying y'all just wait. I got the GOM (hot tub) ahead of me. patience.....:)
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1038. Dakster
Quoting HurricaneSwirl:
Well it was originally thought Julia would be off of Africa and Karl would be in the Caribbean. Early today it was thought Julia would instead be in the Caribbean and Karl would be off of Africa. Now it again looks like Julia will be off Africa and Karl will be in the Caribbean lol.


Who's on First?

Easy for you to say... But yeah, I get the point.
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Quoting GTcooliebai:

If we were to get Karl and Julia tomorrow, we would only be behind by 1, & they're plenty more healthy looking waves coming off Africa.


Yeah, I messed up the post some. 2008 is one ahead of us (At Josephine).
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92L reminds me so much of Gustav, especially right about now. Gustav was in this situation after it passed over mountainous Haiti and weakened considerably and then shocked us in the morning.
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1035. ackee
guess the race is on between 93L And 92L for Julia seem right now 93L is in the lead

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1034. will40
Quoting TexasHurricane:


yeah, that is a weird place for one...


yea they say it may be absorbed by a frontal system
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Quoting HurricaneSwirl:
Well it was originally thought Julia would be off of Africa and Karl would be in the Caribbean. Early today it was thought Julia would instead be in the Caribbean and Karl would be off of Africa. Now it again looks like Julia will be off Africa and Karl will be in the Caribbean lol.


They can't make up their minds.....kinda how it has been this year. Although they seem to have the locations down.
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1032. Levi32
The 12z NAEFS ensembles, Euro Ensembles, and Canadian ensembles are worrisome....with a good portion of the members showing Igor farther west and threatening the SE US coast.





Member Since: November 24, 2005 Posts: 635 Comments: 26654
Quoting TropicalAnalystwx13:
This time last year, we we monitoring fred, which was their second major hurricane.

This time in 2008, we were monitoring Hurricane Ike in the GOMEX.

This time in 2007, Gabrielle. Today's the day that she weakened. Humberto would form tomorrow.

This time in 2006, we were monitoring Gordon, which would become a Category 2 hurricane.

This time in 2004, we were monitoring Ivan.

Besides 2008 and 2005, every year since 2004 we have been ahead. We are tied with 2008 at this time, and 2005 is beating us by 3 named storms.

If we were to get Karl and Julia tomorrow, we would only be behind by 1, & they're plenty more healthy looking waves coming off Africa.
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Well it was originally thought Julia would be off of Africa and Karl would be in the Caribbean. Early today it was thought Julia would instead be in the Caribbean and Karl would be off of Africa. Now it again looks like Julia will be off Africa and Karl will be in the Caribbean lol.
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This time last year, we we monitoring fred, which was their second major hurricane.

This time in 2008, we were monitoring Hurricane Ike in the GOMEX. Josephine already died.

This time in 2007, Gabrielle. Today's the day that she weakened. Humberto would form tomorrow.

This time in 2006, we were monitoring Gordon, which would become a Category 2 hurricane.

This time in 2004, we were monitoring Ivan.

2008 is ahead of us by one, 2005 ahead of us by three. We'll beat 2004 tomorrow, which we are tied with, and tie with 2008.
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Quoting will40:
Link

new circle


yeah, that is a weird place for one...
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Quoting RecordSeason:
Let's see if Saban plays hyper aggressive again, or if he's just going to sit on the 7 and run a lot now...


The college football blog is around the corner..
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they got out the crayons....

60 70 and 10
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Quoting weatherman12345:

going back to negative

Is negative favorable for development? what is this chart by the way?
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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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