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

By: Dr. Jeff Masters , 02:18 PM GMT die 12o September, anno 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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1796. will40
Quoting scott39:
Are they on thier way?


its a NOOA flight upper air measurements maybe a dropzode
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1795. marmark
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?
Great question...will have to do some research!
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Quoting scott39:
Are they on thier way?

They should be.
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Quoting PrivateIdaho:
statistics also impress people so make sure to always include statistics gleaned from the most obscure source possible (or just make them up)and you will be worship like a weather idol.
Don't forget to include a liberal dose of "caps", in order to make your points scream for attention.
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Quoting HadesGodWyvern:
MiamiHurricane

Advance Dvorak Technique from the SSD website
Thanks!
Member Since: September 2, 2009 Posts: 130 Comments: 21194
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...


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?
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1789. angiest
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.


And heading to the ridiculously high TCHP in the NW Caribbean. If it develops a closed circulation by then it may just take off.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
1788. scott39
Quoting Ameister12:

92L defiantly is trying to look better, but I don't think recon will find a tropical depression.
Are they on thier way?
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1787. Max1023
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??


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 :(
Member Since: July 22, 2008 Posts: 1 Comments: 286
1786. HadesGodWyvern (Mod)
MiamiHurricane

Advance Dvorak Technique from the SSD website
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1784. JLPR2
Quoting scott39:
Im just takin a guess here. It looks like 92Ls COC is about 16.5N 72.5W. The is a good burst of convection around that area rotating counter clockwise. I think 92L may be getting its act together.


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.
Member Since: September 4, 2007 Posts: 7 Comments: 8747
Quoting HadesGodWyvern:
Severe Tropical Cyclone Igor (AL112010)
========================================

2010SEP12 211500

CI 6.5
937.0
127.0
Initial 6.5
Adjusted 6.7
Raw 6.8

---
geez, 130 knots already.. wasn't this a around 85 this morning. =P
Where do you find that data?
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting scott39:
Im just takin a guess here. It looks like 92Ls COC is about 16.5N 72.5W. The is a good burst of convection around that area rotating counter clockwise. I think 92L may be getting its act together.

92L defiantly is trying to look better, but I don't think recon will find a tropical depression, tonight.
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1780. marmark
Quoting IKE:


Interesting that none of them hit Florida or went into the GOM. Period of 151 years.
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...
Member Since: Posts: Comments:
1779. Max1023
Quoting HadesGodWyvern:
Severe Tropical Cyclone Igor (AL112010)
========================================

2010SEP12 211500

CI 6.5
937.0
127.0
Initial 6.5
Adjusted 6.7
Raw 6.8

---
geez, 130 knots already.. wasn't this a around 85 this morning. =P


It was a 70 at 5am. At 5pm it was 120. That's 50 knots in 12 hours, with 45 of that in 9 1/2.
Member Since: July 22, 2008 Posts: 1 Comments: 286
Quoting Hurricanes101:


Exactly, it would be nice if some would follow the lead of people like Drak, Levi, StormW and Kman. They don't always agree, but when they disagree with each other they do it the right way.


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??
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1777. HadesGodWyvern (Mod)
Severe Tropical Cyclone Igor (AL112010)
========================================

2010SEP12 211500

CI 6.5
937.0
127.0
Initial 6.5
Adjusted 6.7
Raw 6.8

---
geez, 130 knots already.. wasn't this a around 85 this morning. =P
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1776. scott39
Im just takin a guess here. It looks like 92Ls COC is about 16.5N 72.5W. The is a good burst of convection around that area rotating counter clockwise. I think 92L may be getting its act together.
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1775. Max1023
Quoting RecordSeason:


Not quite sure what to make of this frame. The white donut has a slight hole in it in SW quadrant, but the nested gray in SE quadrant got bigger AND there is some nested gray in NW quadrant too and speckles in the NE quadrant now...


The eyewall is wrapping around, that hole should be filled on the next frame. On a hurricane this strong the clouds move a half circle an image.
Member Since: July 22, 2008 Posts: 1 Comments: 286
1774. Melagoo
Link

I wonder if those small outbursts are to do with IGOR's rapid intensification
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Glad to read that Recon is going in. Always interesting to read the reports coming back:

Member Since: September 10, 2007 Posts: 0 Comments: 11456
Quoting TropicalAnalystwx13:
Earl caused $150 million

Hermine caused $150 million

Earl did $250 million, Hermine did $200 million the last time I checked Wikipedia.
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1771. Max1023
OHC is low under Igor BTW. Also the ADT is a full hour behind the WU imagery. Look under Tropical and Hurricane, the image updates every 8 minutes.
Member Since: July 22, 2008 Posts: 1 Comments: 286
Quoting PcolaDan:


Unfortunately it is becoming a forum of "I'm right and you're wrong and if you disagree you're an idiot."


I agree 100% with this comment

Taco :o)
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1769. IKE
Quoting Walshy:
I don't like to see this map for Igor. Given if Igor gets south-west of Bermuda, 66% of the storms went on to hit land in either North Carolina or Canada. The only other storm to not hit land was a storm that recurved as a CAT 2 around New York and almost hit Canada. If Igor hits CAT 5 the best climatology storm would be... Hurricane Isabel.



Interesting that none of them hit Florida or went into the GOM. Period of 158 years.
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Quoting DestinJeff:
I may have misspoke earlier....

I now think, based on obs and water vapor imagery, as well as weeks of doing this kind of thing, that Igor has about a 49.5% chance of a CONUS strike and a 50.5% chance of a recurve.

I will repeat myself continuously until people start to think I know what I am talking about.

It is just too soon to know for sure. Another 35 hours and 45 minutes, then maybe I will be able to offer a more concrete forecast.
statistics also impress people so make sure to always include statistics gleaned from the most obscure source possible (or just make them up)and you will be worship like a weather idol.
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Member Since: Posts: Comments:
Quoting JLPR2:
There is just no end in sight.



Yea, but waves coming off Africa now means they don't arrive near CONUS until the last week of September. Igor may be the last Cape Verde that "semi" makes it across the Atlantic. Trough strength and frequency will continue to increase from here on out.
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1764. help4u
Fish storms as far as eye can see.
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1762. Max1023
Quoting leo305:


I don't think the water is the main issue, I think the upper air conditions wont allow it


The upper air conditions are nearly perfect...Igor is probably within 20mb of the MPI for his area.

General Water Temp/MPI rule:

26.5 degrees = Category 2
27.0 degrees = Category 3
28.0 degrees = Category 4
28.0(High OHC)- 29.0 (Low OHC) = Category 5
Member Since: July 22, 2008 Posts: 1 Comments: 286
1761. IKE
Quoting marmark:
Can't get over how the season has ramped up so quickly. Good to see you, Ike!


Hey.
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1759. jonelu
does anyone have a link of Igor making his transition from TS to Cat4?
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1758. Walshy
I don't like to see this map for Igor. Given if Igor gets south-west of Bermuda, 66% of the storms went on to hit land in either North Carolina or Canada. The only other storm to not hit land was a storm that recurved as a CAT 2 around New York and almost hit Canada. If Igor hits CAT 5 the best climatology storm would be... Hurricane Isabel.

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Quoting DestinJeff:
IT IS THE DOOMICANE!

by the way, I claim DOOMICANE as my own!

What did I tell ya? We are quite simply doom.
Member Since: August 18, 2008 Posts: 0 Comments: 884
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1755. marmark
Can't get over how the season has ramped up so quickly. Good to see you, Ike!
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Quoting JLPR2:
There is just no end in sight.



Ya know, I have always wanted a hurricane for Christmas!
Member Since: August 11, 2010 Posts: 0 Comments: 895
1753. Max1023
Quoting RecordSeason:
1735:

Igor has missed that trough, which is what I said this morning.

Yes, you are going to get a very close call in PR, maybe even landfall.

It's just like Earl, track is going to shift west more and more.


Igor would need to go DUE WEST for 4 days to hit PR. The farthest south it is likely to get is 100 miles NE of the BVI, and even that is unlikely. You need a Dean-Strength ridge to keep a major cane at due west for that long, which we don't have. Igor will turn, the question is when and how sharply.
Member Since: July 22, 2008 Posts: 1 Comments: 286
Earl caused $150 million

Hermine caused $150 million
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1751. will40
Quoting Vero1:


confusing?


yea the Slower part is what is bothersome
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Quoting DestinJeff:
I may have misspoke earlier....

I now think, based on obs and water vapor imagery, as well as weeks of doing this kind of thing, that Igor has about a 49.5% chance of a CONUS strike and a 50.5% chance of a recurve.

I will repeat myself continuously until people start to think I know what I am talking about.

It is just too soon to know for sure. Another 35 hours and 45 minutes, then maybe I will be able to offer a more concrete forecast.
Nice DJ. ROFL
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1749. Gearsts
Quoting JLPR2:
There is just no end in sight.

OMG Big wave!
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Quoting Herbertsbox:
Right now the NHC has Igor starting its curve at about 51.5 west. Curious to see when and where it does. I assume it has been missing the forecast point up until now...yes?


Only the last day or so of forecasts have been within the cone.

NHC Forecast Error for Igor


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Quoting JLPR2:
There is just no end in sight.

Yup. That's PGI45L. It's accompanied by a pretty well-defined mid level circulation.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
1746. leo305
Quoting Max1023:


Igor is not undergoing RI anymore winds wise, the organization suggests about 10 knots per 6 hours of strengthening. To me RI starts at 15. For a hurricane of Igor's strength though intensification after Category 4 is rare.

Pressure wise Igor is probably deepening at about 2-3mb an hour, near the line. At the rate it's going it would be a Cat 5 by 5am, however I doubt that Igor will continue to strengthen that far this early. The water temps do not support it.


I don't think the water is the main issue, I think the upper air conditions wont allow it
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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.