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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Igor Pressures

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Won't 92L's large size make it take much longer to spin up?
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1118. bassis
It's just my amature observations but I dont recall seeing a front like is set up right now with it going from ala. to tex then concecting to a low that goes all the way to Can.
Member Since: September 8, 2008 Posts: 0 Comments: 423
Quoting stormwatcherCI:
Isn't 93L at D-Max now ?


Probably close.. I think it's around 1:30 where 93L is.
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Quoting CosmicEvents:
And thus it begins.
Why, why, why did they have to name this Igor?
Next time around, let's go with Isaiah, or even Ishkabble.
How about Ichabod ?
Member Since: October 9, 2008 Posts: 0 Comments: 8391
Quoting Legion:


LOL, how could I forget that, Otto Mann, yeah, you'd have to go with him for sure over Otto Graham, much more recognizable, unless you're a football historian or 70+ years old.


Otto Preminger would be a good choice also.
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92l still not developed and igor having fun out to sea. Nothing different from my earlier great posts!:)
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Quoting CybrTeddy:
93L's throwing on some deep convection too.
Isn't 93L at D-Max now ?
Member Since: October 9, 2008 Posts: 0 Comments: 8391
Quoting CosmicEvents:
And thus it begins.
Why, why, why did they have to name this Igor?
Next time around, let's go with Isaiah, or even Ishkabble.


No, they are not Disney names
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Quoting Levi32:
Something I thought I'd point out....yesterday was the traditional half-way point of the hurricane season, and we're at 9 storms. If we simply double that we get 9 more in the 2nd half for a total of 18 named, which is my forecast. It could possibly even end up more than that considering that the 2nd half of the season typically has more storms than the first half, especially in La Nina years. We're already looking at 2 more possibly getting named next week. So....our forecasts don't look so crazy now do they :)
Hi Levi. Agreed. Lots of complaining about lack of activity at times Those who understand how the tropics can evolve, always wait for the season to end before declaring anything. Trolls like to provoke.
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Why is everyone comparing 2005 to 2010, 2005 was a ones in a life time year?
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Quoting StormW:
You can see how large of an envelop with Igor

IR2

Yes I definitely agree with you on that. This storm is massive
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Quoting Bobbyweather:
AL, 11, 2010091200, , BEST, 0, 176N, 417W, 65, 992, HU

Igor is a hurricane
And thus it begins.
Why, why, why did they have to name this Igor?
Next time around, let's go with Isaiah, or even Ishkabble.
Member Since: August 3, 2005 Posts: 10 Comments: 5605
93L's throwing on some deep convection too.
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Igor Winds
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Link
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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


2%
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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
That's full of win.
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Quoting Ameister12:
Igor definitely looking like a hurricane, but dry air is still a problem. Still messing with the west side of the storm.



And more dry air is ahead.
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Igor definitely a hurricane, but dry air is still a problem. Still messing with the west side of the storm.

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Quoting TropicalAnalystwx13:




Earl's at T-4.0


Were on to Igor now ;)
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ATCF files have updated for Igor, and Igor has become our 4th hurricane of the active 2010 Atlantic Hurricane season.

AL, 11, 2010091200, , BEST, 0, 176N, 417W, 65, 992, HU

Hurricane Igor
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Quoting Bobbyweather:
AL, 11, 2010091200, , BEST, 0, 176N, 417W, 65, 992, HU

Igor is a hurricane


Dangit! I'm always too slow :(
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Earl's at T-4.0
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Quoting Levi32:
Something I thought I'd point out....yesterday was the traditional half-way point of the hurricane season, and we're at 9 storms. If we simply double that we get 9 more in the p2nd half for a total of 18 named, which is my forecast. It could possibly even end up more than that considering that the 2nd half of the season typically has more storms than the first half, especially in La Nina years. So....our forecasts don't look so crazy now do they :)
...,nope wouldn't be suprised if the 2010 season exceeds 08's ace imoo....
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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


It's almost like going to Disney and hear the same names.
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AL, 11, 2010091200, , BEST, 0, 176N, 417W, 65, 992, HU, 64, NEQ, 15, 10, 5, 15, 1011, 240, 10, 0, 0, L, 0, , 0, 0, IGOR, S,


9-4-2
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AL, 11, 2010091200, , BEST, 0, 176N, 417W, 65, 992, HU

Igor is a hurricane
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This will be a hurricane at 11.

11/2345 UTC 17.6N 41.7W T4.0/4.0 IGOR -- Atlantic
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Guys, Gals and Others:

There is a problem with 92L, it is south of Puerto Rico rain forest, "EL Yunque" where the extra terrestial have their base. Until 92L don't left the area it will not spark. So take it easy.
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1082. JRRP
.Link
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AS Keeeper would say mark 15.5N/69W
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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..that's awesome!
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1079. Levi32
Quoting largeeyes:


Polar vortex? Is this a bit early for that? Does it show any unusual temp anomalies?


It's not like the end of the world or anything but it's generally the label given to the strongest 500mb low in the northern hemisphere, and that would be it at that time.
Member Since: November 24, 2005 Posts: 635 Comments: 26652
Quoting superpete:
1064 Neapolitan... Just Wonderful !!
Hey SP, what's up ? You ready ? LOL
Member Since: October 9, 2008 Posts: 0 Comments: 8391
1077. Levi32
Something I thought I'd point out....yesterday was the traditional half-way point of the hurricane season, and we're at 9 storms. If we simply double that we get 9 more in the 2nd half for a total of 18 named, which is my forecast. It could possibly even end up more than that considering that the 2nd half of the season typically has more storms than the first half, especially in La Nina years. We're already looking at 2 more possibly getting named next week. So....our forecasts don't look so crazy now do they :)
Member Since: November 24, 2005 Posts: 635 Comments: 26652

The NOAA G-IV will takeoff Sunday 9/12 at 1730 UTC from Tampa, fly AL92
near environment and inner core and recover in St. Croix.

NOAA will fly one P-3 (N43) from Tampa, departing 20 UTC on Sunday,
conduct a mission into AL92/PGI44 and land in St. Croix. That would be
concurrent with the G-IV. There would be a mission by the other P-3
(N42) into AL92, take off at 08 UTC Monday from Tampa, landing in St.
Croix.

Further missions will occur Monday and Tuesday, with the same takeoff
times, returning to St. Croix Monday, and returning to Tampa Tuesday.


NASA/GRIP:

NASA plans a DC-8 departure from Ft. Lauderdale at 18 UTC Sunday 12
Sept. to target AL92 in a 9-h flight, 5 h on-station. Landing will be
back in Ft. Lauderdale. A follow-on mission into AL92 is possible on
Monday, possibly one hour later. Another mission could follow on
Tuesday.

The Global Hawk is planning a 25-hour flight into AL92 departing Sunday
at 1130 UTC. There will be an estimated 5 h on-station.
Member Since: July 12, 2007 Posts: 0 Comments: 6049
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:



Polar vortex? Is this a bit early for that? Does it show any unusual temp anomalies?
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Quoting TropicalAnalystwx13:


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.


Yeah exactly there is a very strong chance that we will have 5 named storms for September before the month is even half over. Which is just insane, even for the peak of the season. If the wave behind 93L gets named it may not do so until after half of the month is over, but it bears watching.
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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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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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