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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Quoting joetuttledays:
Thank you aall so much for the welcome. Let me just jump right in. This is only an opinion, from what I see I dont believe the Low's coming off the east coast of the US will dig far enough south to recurve Igor. What I think will happen they will have enough of an influence to lift Igor to the NW but I just dont see the recurve. What feedback-if any?


Take a look at this WV loop

You will see two troughs. The first is now off the East coast and will reinforce the ridge behind it. Igor will not be caught by the first trough.

The second trough can be seen pushing through the Great lakes area now. That is supposed to dig down and pick up Igor. If that second trough is flat and does not amplify it will only pull Igor up to the WNW and NW for a time but may not effect a recurve. Behind that trough another ridge will then build back in which could force Igor back towards the West and WNW.

As usual it is all about timing and strength of the various features. Stay tuned.
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Quoting reedzone:
12Z GFS 60 hours..


18Z GFS 48 hours (still running)


Little quiz time :P
There's a signifigant change on the 18Z, anyone like to show me what the change could be?


What is that line labelled 150 that now envelops Igor and the storm behind it? It wasn't there before.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
I suspect 93L will be named Julia before 92L, 92L needs a closed low and disturbances that develop in that area for some reason has a problem closing off til well in the western caribbean usually south of Jamica or between the caymans and honduras, of course they can go from a depression to major hurricane in 24 hours in that area also.
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Quoting PensacolaDoug:
The "John Hope" rule (god I miss that guy) is showing its power today.



Yup!
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The "John Hope" rule (god I miss that guy) is showing its power today.
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815. mbjjm
Quoting KanKunKid:


The answer is in the models, or guess. It is of significance because the models weren't developing it before. Now, if they are, there has to be a reason, and it doesn't look like circulation. We should see a plot soon, that may answer your question(s)and my musings.


Folks put to much trust in the models.The answer is not in the models, the models are simply guidance.
Member Since: August 23, 2010 Posts: 0 Comments: 310
Quoting KEEPEROFTHEGATE:
Looks like Andrew (sorta).
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Quoting Tazmanian:
Igor is my boss i tell it what too do


and when i say its not a fish then its not a fish


now Taz you have to be his boss to do that
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what did NOAA find with their plane today, any idea?
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12Z GFS 60 hours..


18Z GFS 48 hours (still running)


Little quiz time :P
There's a signifigant change on the 18Z, anyone like to show me what the change could be?
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Quoting AtHomeInTX:


I agree. I'm starting to like this homebody life style as compared to the other wandering kind. Lol.


wandering is wayyyyyyyyyyyyyyy too expensive hee hee
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Igor is my boss i tell it what too do


and when i say its not a fish then its not a fish
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Quoting will40:


me to i had rather just sit right at home


I agree. I'm starting to like this homebody life style as compared to the other wandering kind. Lol.
Member Since: August 24, 2010 Posts: 0 Comments: 253
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Hey, Joe!

Come on in, the blog temperatures seem just fine, occasionally chaotic - sometimes like the weather. But, if you like following the tropics, this is the place to be - good folks here. Enjoy.
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92L (this morning) explosive convection and looked to be well on its way to becoming a Tropical Depresson or Storm. This evening 92L looks very beat up and abused with little to no convection.

Tomorrow morning?
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Great ventilation courtesy of high pressure aloft



But next to nothing going on at the surface



Until we see some convergence at the surface 92L will not develop a closed low
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i am continue to read from some on here that Igor is going out to sea and others that say it is not, quite frankly alot of things have to come in place for Igor to recurve, even though right now it looks like it will recurve there is a good possibility the trof may not be strong enough to pull it out
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Quoting joetuttledays:
Hello Everyone allow me to introduce myself my name is Joe and Im brand new here. Nice to meet all of you


Welcome Joe! I hope you enjoy the blog.
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Thank you aall so much for the welcome. Let me just jump right in. This is only an opinion, from what I see I dont believe the Low's coming off the east coast of the US will dig far enough south to recurve Igor. What I think will happen they will have enough of an influence to lift Igor to the NW but I just dont see the recurve. What feedback-if any?
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Quoting Caymanfishnut:
Go away!!!!




+1 agreed 100%
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Quoting joetuttledays:
Hello Everyone allow me to introduce myself my name is Joe and Im brand new here. Nice to meet all of you


Howdy Joe! I'm fairly new myself!

WELCOME!
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Quoting joetuttledays:
Hello Everyone allow me to introduce myself my name is Joe and Im brand new here. Nice to meet all of you


welcome Joe
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Quoting joetuttledays:
Hello Everyone allow me to introduce myself my name is Joe and Im brand new here. Nice to meet all of you


Hi Joe, welcome to the blog.
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Hello Everyone allow me to introduce myself my name is Joe and Im brand new here. Nice to meet all of you
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Quoting stormwatcherCI:
I think he means Gilbertish in regards to the location 92L is attempting to organize.


In regards to its eventual track.
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Quoting mbjjm:


We do not need model support to know 92L is going to develop. The question is when, how rapidly and at one point.


GFS is doing some interesting things to the Gulf ridge as Igor approaches the islands, and I would like to have something to look at....
Member Since: August 26, 2006 Posts: 16 Comments: 4766
Quoting asgolfr999:
Ike

I see no west winds meaning no circulation as such. Are they a lot further south? I mean from looking at the radar you posted.


There is no evidence of West winds. Aruba has winds out of the NE on the SW side of the system. Of course, given its very weak state there might be very weak West winds to the North of Aruba but I doubt it. Based upon the obs we have I see SE winds in the Windwards and NE winds in the Leewards. 92L is probably a sharp wave that is still open on the West and SW sides.

Queen Beatrix Airport, Aruba (Airport)
Updated: 50 min 29 sec ago
88 %uFFFDF
Scattered Clouds
Humidity: 58%
Dew Point: 75 %uFFFDF
Wind: 9 mph from the NE
Wind Gust: -
Pressure: 29.75 in (Falling)

Visibility: 37.0 miles
Clouds: Few 1772 ft
Mostly Cloudy 34449 ft
(Above Ground Level)
Elevation: 59 ft

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789. mbjjm
Quoting angiest:
18Z GFS may be developing 92L...


We do not need model support to know if 92L is going to develop. The question is when, how rapidly and possible track
Member Since: August 23, 2010 Posts: 0 Comments: 310
787. IKE
Quoting asgolfr999:
Ike

I see no west winds meaning no circulation as such. Are they a lot further south? I mean from looking at the radar you posted.


Here's the closest buoy... at 15N and 67.5W....Link

Not sure on west winds.
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Quoting crashingwaves:




I totaly agree here, very well said.
+5
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Quoting AtHomeInTX:


Lol. I bet you do! Hope ya get a lifetime more of 'em. :)


me to i had rather just sit right at home
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18Z GFS may be developing 92L...
Member Since: August 26, 2006 Posts: 16 Comments: 4766
Quoting will40:


the GFS and I love those east coast trofs lol


Lol. I bet you do! Hope ya get a lifetime more of 'em. :)
Member Since: August 24, 2010 Posts: 0 Comments: 253
Quoting aislinnpaps:


He's a meteorologist out of Lake Charles. He is factual and I've never heard him play a storm more than it is.


Ah ok. He may not broadcast over here on the Texas side. We get most of ours from Beaumont stations. Might he have a website where he does forecasting? I'd like to hear/read his opinions. Off to google him. Lol.
Member Since: August 24, 2010 Posts: 0 Comments: 253
Ike

I see no west winds meaning no circulation as such. Are they a lot further south? I mean from looking at the radar you posted.
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Things are looking real swell for South Florida this year so far :) Thank Goodness !
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I will say this, at th present time 92 looks like a giant Jellyfish over Puerto Rico
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Igor is flaring and 92 is fading
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Quoting reedzone:
Out of all the models, based on Igors movement, the UKMET seems to be the best one along with the NHC track.


the GFS and I love those east coast trofs lol
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Out of all the models, based on Igors movement, the UKMET seems to be the best one along with the NHC track.
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Quoting AtHomeInTX:


Yes they do Will. Thanks for the link. :D Hoping they keep us both out of trouble.


looks ok if nothing changes right now :-)
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Quoting AtHomeInTX:


I'm not sure who Rob Robbin is. Don't think I've listened to the radio since I got cds. Lol. But I'll be keeping an eye out here and there about these systems. If that high holds we'll be in the clear for this 92L anyway. That's some high pressure ridge he showed. That's what we need to watch whether its moving or weakening. Anybody got a link to the steering layers? Anyway fingers crossed. :)


He's a meteorologist out of Lake Charles. He is factual and I've never heard him play a storm more than it is.
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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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