92L still a threat to develop; Igor a hurricane; TD 12 forming near Africa

By: Dr. Jeff Masters , 2:18 PM GMT on September 12, 2010

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Tropical disturbance (92L) over the Central Caribbean, a few hundred miles south of the Dominican Republic, remains a threat to develop into a tropical depression. Satellite loops this morning show 92L may be starting to form a surface circulation, and an Air Force Hurricane Hunter aircraft will investigate 92L this afternoon to see if a tropical depression is forming.

The storm has only a modest area of heavy thunderstorm with limited low-level spiral banding and upper-level outflow, thanks to an infusion of dry air last night that disrupted the storm. Long range radar out of Puerto Rico shows that heavy rains are affecting that island, but there is no rotation to the radar echoes evident. Wind shear over 92L is low, 5 - 10 knots. The waters beneath are hot, 29.5°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 to west-northwest at 15 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 Belize or Mexico's Yucatan Peninsula on Wednesday. On this track, the southern Dominican Republic can expect heavy rains of 3 - 6 inches today through Monday morning; southern Haiti can expect similar rains tonight through Monday night, and Jamaica and the Cayman Islands can expect heavier rains of 4 - 8 inches Monday and Tuesday. Eastern Cuba can expect rains in the 2 - 4 inch range. Once 92L crosses the Yucatan, the ridge of high pressure steering it is expected to remain in place, forcing 92L to a second landfall in Mexico south of the Texas border.

Intensity forecast for 92L
NHC is putting the odds of 92L developing into a tropical depression by Tuesday at 50%; I'd put them higher, at 70%. However, time is running out for 92L to become a hurricane before hitting the Yucatan Peninsula on Wednesday. Given the current disorganized state of 92L, it would be difficult for it to intensify quickly enough to become a hurricane by then. The storm may also suffer another of its mysterious evening collapses, where it loses most of its heavy thunderstorm activity. However, the SHIPS model predicts wind shear will remain low, 5 - 10 knots, through the period, and 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. There are a number of research flights being made into 92L this afternoon that should help long-term efforts to make better predictions in the future on whether or not disturbances like this will develop or not.


Figure 2. Morning satellite image of Igor.

Igor
Hurricane Igor appears destined to become a large and powerful major hurricane over the Central Atlantic in the days to come. Wind shear is low, 5 - 10 knots, and is expected to drop below 5 knots for the next five days. Waters are warm, 28°C, and will warm to 29°C by Wednesday. Igor has moistened its environment enough to keep the dry air of the Saharan Air Layer (SAL) at bay. Igor is undergoing a period of rapid intensification today, and will probably be a Category 3 or 4 hurricane by Monday.

The track forecast for Igor remains unchanged. Igor will move west under the influence of a strong ridge of high pressure for the next 2 - 3 days, then turn more to the west-northwest then 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 does have a small chance of making landfall on the U.S. East Coast or Canada. Climatology shows that about 15% 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 10% for Canada. The forecast steering pattern for the period 5 - 12 days from now from the ECMWF and GFS models 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. Recent runs of the ECMWF model indicate that these troughs may not be as intense as previously thought, so it is possible Igor has a higher chance than usual to hit land than climatology suggests. One wild card may be the possible development of TD 12 behind Igor. If TD 12 develops into a hurricane, and moves close to Igor, as some of the models are suggesting, the two hurricanes could rotate around a common center, forcing Igor more towards the coast of the U.S. The long term fate of Igor is difficult to predict at this point.

Tropical Depression Twelve forms
Tropical Depression Twelve formed between the Cape Verdes Islands and coast of Africa this morning, and is already affecting the Cape Verdes with winds near tropical storm strength; sustained winds of 35 mph were recorded in the northwest Cape Verdes this morning. You can follow the progress of TD 12 through the Cape Verdes today using our wundermap.

Next post
I'll have a new post Monday morning, and perhaps late this afternoon if events warrant.

Jeff Masters

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I'm going on a limb and saying that Igor is currently a Category 5 Hurricane.
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ADT suggests that 12L has winds of 50mph.

CI# /Pressure/ Vmax
3.0 /1000.0mb/ 45.0kt
Member Since: September 2, 2009 Posts: 130 Comments: 21194
looking at the map when you first enter WUBA there are alot of high's in the western part of the US. One trough pushing off of the coast and another smaller one in the central US. What is the talk of a second trough?
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Quoting all4hurricanes:
Who else thinks Igor will be a category 5 by 11, or at least at some point in his life?

I think it is Close right now to being a Cat 5 but remember it can only hold a Cat 5 for approx 12 hrs before it starts to lose some and go through a EWR....

Taco :o)
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1842. Gearsts
Quoting Ameister12:

Yeah. This is probably longest I've seen 92L hold some descent convection.
Theres a better spin now finally.
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Quoting all4hurricanes:
Who else thinks Igor will be a category 5 by 11, or at least at some point in his life?

I think Igor will be a strong category 4 tonight and possible become a category 5 in the morning.
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1839. scott39
Local Chief Met just said 92L will move NW for the next several days. I dont know what to believe anymore?LOL
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Quoting MiamiHurricanes09:
The RAW T# is flirting with 7.0, which would indicate a pressure of 921mb and winds of 140kt (161mph).

2010SEP12 211500 6.5 937.0/ +2.0 /127.0 6.5 6.7 6.8 3.2T/18hr OFF OFF 14.34 -70.73 EYE 27 IR 17.65 46.59 COMBO

EEK!
Member Since: July 7, 2010 Posts: 0 Comments: 5725
anyone seen Kman, he was dead on with a few storms. Would like his input here with this monster.
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1836. MZT
Quoting angiest:


Actually the black line is too far west there. :P
Yeah Ike was tricky... Galveston was really lucky to get the "left shoulder"

I think there were even forecast maps for Ike a few days earlier than my example, showing him curving away from the USA completely.

I respect the NHC's work, and they keep getting better at their game. But even the experts need to revise their projections. Never let a fully formed hurricane go more than a day, without checking the lastest forecast!
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Quoting PrivateIdaho:
I knew I was FORGETTING something!!!!
ROFL, thanks.
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1834. leo305
Quoting Ameister12:

Yeah. This is probably longest I've seen 92L hold some descent convection.


it's got the structure of a developing cyclone, I say it's going to go through rapid intensification tonight
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Quoting all4hurricanes:
Who else thinks Igor will be a category 5 by 11, or at least at some point in his life?
Me.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
1832. xcool
scott39 .yep i think td come soon
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting scott39:
Now its a wait and see if it holds. Its so big just like Alex and next to land. I hope it doesnt go thru the Yucatan Channel and end up in the GOM!


It's going in the GoM. That much is certain. Just possibly not the northern GoM.
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To be honest, I think this is making a run at Category 5 status. Lets see what happens.
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| /SATPRODUCTS/TC/tc10/ATL/92L.INVEST/amsre/wind
20100912.1735.aqua-1.wind.x.92LINVEST.25kts-1007mb-158N-721W.29pc.jpg |
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1828. mbjjm
92L just watch for the "mysterious" evening collapse later
Member Since: August 23, 2010 Posts: 0 Comments: 310
IMO he is right on the verge or might already be one.
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1826. Gearsts
Quoting CybrTeddy:
EXTREMELY intense hurricane, what a beauty!
And look at that ring!getting stronger.
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Who else thinks Igor will be a category 5 by 11, or at least at some point in his life?
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1824. angiest
GFS is way off on Igor's intensity. Wonder how that impacts the track it will take.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
1823. scott39
Quoting xcool:
RECON find pressure 1007 mb 92l
Its something--Dropped 2mb in 24 hours.
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Quoting stormpetrol:
92L looks like it might finally be getting its act together, jmo.

Yeah. This is probably longest I've seen 92L hold some descent convection.
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The RAW T# is flirting with 7.0, which would indicate a pressure of 921mb and winds of 140kt (161mph).

2010SEP12 211500 6.5 937.0/ +2.0 /127.0 6.5 6.7 6.8 3.2T/18hr OFF OFF 14.34 -70.73 EYE 27 IR 17.65 46.59 COMBO
Member Since: September 2, 2009 Posts: 130 Comments: 21194
1819. scott39
Quoting xcool:
deep convection 92l
Now its a wait and see if it holds. Its so big just like Alex and next to land. I hope it doesnt go thru the Yucatan Channel and end up in the GOM!
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NW carribbean water temps are off the chart and deep as hell, but its taking to long and not able to pull a feat off like that. LOL
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EXTREMELY intense hurricane, what a beauty!
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1816. xcool
RECON find pressure 1007 mb 92l
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting PSLFLCaneVet:
Don't forget to include a liberal dose of "caps", in order to make your points scream for attention.
I knew I was FORGETTING something!!!!
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Ike, though it looks like you are going to be getting Julia/Karl. Either of them will partake the name of the blob in the Caribbean, that blob will be part of the determining factor in Igor's Track.
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Quoting barotropic:


My highest praise to thou holy 'them'. If only all on this board could be them. Common...LOL, have you ever seen someone get slammed for disagreeing with Storm in the morning on this board??


Only when they disagree with nothing to substantiate their reasoning. And we have a lot of those here. Especially more recent bloggers.
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1812. IKE
Latest GFS shows a 1008mb low in the western Caribbean(on 92L), on some of the individual 6 hour frames, but the 850mb vorticity with it is almost nonexistent @ 48 hours.....

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1810. xcool
deep convection 92l
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Masters cracks me up....he said 92L probably wont be able to became a hurricane before hitting the Yucatan because it's taking too long to develop.
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92L looks like it might finally be getting its act together, jmo.
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1807. angiest
Quoting MZT:
When it comes to eastcasting, westcasting, speculating on the cone of a new system, this is all I need to remember... And it was not that long ago. Forecasts are subject to change!

Where Ike was originally going to land:




Where he ended up:




Actually the black line is too far west there. :P
Member Since: August 26, 2006 Posts: 16 Comments: 4766
Quoting goldenpixie1:


Interesting....is there a graphic of the storms that have made landfall in Florida over the past say 5 years that shows also the track from where they started?


Link
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1805. scott39
Quoting will40:


its a NOOA flight upper air measurements maybe a dropzode
Thier decision to check or not.
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1804. Fiscal
Looks like (from SSD) the last 3 sets of raw T# has been 6.7, 6.9, 6.8, so we should see the Final T# rising a little soon, surely?
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Quoting marmark:
Indeed...I believe the ones to worry about (for FL) are the waves exiting at a lower latitude. I believe that Frances came off or stayed south much longer. There is a wave behind this one exiting way south. Something to watch...

On the other hand...that map has a sample size of eight storms. Hard to determine very accurate probabilities.
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Quoting Hurricanes101:
and don't get me wrong, there are people who blindly ignore evidence and say a storm will hit here or there, trust me I know that

however most of those people pop up every once in awhile to get a rise out of others. All of the people I would consider regulars have shown evidence to support their predictions.

It would be great if for once instead of people calling each other out for their opinions, that people could actually have a civil discussion about their differing opinions.

I think Houston needs to watch Igor verrrry closely.
(disclaimer: I am known, at times to toss out a nugget of sarcasm without specifically saying that I am doing so. Sometimes taken for seriousness or actual derision.)
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Quoting will40:


its a NOOA flight upper air measurements maybe a dropzode
noaa p3 flying down about two hours to go. will be flying around 12,000 feet. so if there are west winds they will know.
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1800. MZT
When it comes to eastcasting, westcasting, speculating on the cone of a new system, this is all I need to remember... And it was not that long ago. Forecasts are subject to change!

Where Ike was originally going to land:




Where he ended up:


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1799. scott39
Quoting JLPR2:


Yeah, seems ready to get going, I believe this is the first time in it's lifetime in which it has built convection at this hour.
I think so too.
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Forecasting tropical cyclones is not an exact science...it's more a science of probability based on the interaction between the various forces at work.
.
.
There are times when the NHC calls for a CONUS landfall from a major hurricane. Are they sure? No, but this forecast is based on the probabilities. And nobody has ever called the NHC "wishcasters".
..
.
There is no definite track for any tropical cyclone. But there are definite probabilities. When one over and over takes the underdog, the 1%-5% chance that leads to land...that's the definition of wishcaster.
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Quoting Max1023:


Once 2 years ago I actually won an argument with storm, for 10 minutes I had convinced people that I knew what I was doing lol. I haven't been able to repeat that feat though :(


Dont feel bad..Lennon and Mccartney are the most successful composers in popular music history. They cant read or write a note!!
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1796. will40
Quoting scott39:
Are they on thier way?


its a NOOA flight upper air measurements maybe a dropzode
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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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