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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Quoting goldenpixie1:


That's an awesome resource! Thanks!


You're welcome. It's been a very resourceful site for me. I've used it in many of my papers. It is great for those who work with GIS also because you can export the tracks to GIS shapefiles.
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Quoting superpete:
Sounds like Gustav?
Yep.
Member Since: October 9, 2008 Posts: 0 Comments: 8418

The Little Invest That Could.
Member Since: August 9, 2009 Posts: 10 Comments: 5070
Quoting Ameister12:

I think Igor will be a strong category 4 tonight and possible become a category 5 in the morning.
Igor could very well have winds close to category 5. I would say right now 155 mph based on the latest pass and satellite information.
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1892. Walshy
Sorry for my climatology biased post guys. Igor may not get further south-west of Bermuda, I apologize. I did not even make a prediction in that post and sorry for the bold words.

I was trying to make the point if Igor hit CAT5 Isabel is the only comparable storm based purely on that map. The other part was a high risk chance for NC and Canada based entirely on that map. Again, I apologize if I sounded to alerting for or to far west...ect.
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Ok 5 to 10 kts lets see what happens now
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Quoting WeatherNerdPR:

I thought it was JULIA.


I corrected myself.
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Weren't people saying last week that the system after Igor was going to be the one to watch? The pattern would have totally shifted when that one exited Africa? What about now? Still waiting for that pattern to change, I guess.
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Quoting stormwatcherCI:

Anyone remember this ? This is why people in the central and western Caribbean need to keep a close eye on 92L. Where it is now anything is possible.

It formed on the morning of August 25, 2008, about 260 miles (420 km) southeast of Port-au-Prince, Haiti, and rapidly strengthened into a tropical storm that afternoon and into a hurricane early on August 26. Later that day it made landfall near the Haitian town of Jacmel. It inundated Jamaica and ravaged Western Cuba and then steadily moved across the Gulf of Mexico.[3][4]

I remember it very well, hurricane Gustav (2008).
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Quoting stormwatcherCI:

Anyone remember this ? This is why people in the central and western Caribbean need to keep a close eye on 92L. Where it is now anything is possible.

It formed on the morning of August 25, 2008, about 260 miles (420 km) southeast of Port-au-Prince, Haiti, and rapidly strengthened into a tropical storm that afternoon and into a hurricane early on August 26. Later that day it made landfall near the Haitian town of Jacmel. It inundated Jamaica and ravaged Western Cuba and then steadily moved across the Gulf of Mexico.[3][4]
Sounds like Gustav?
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1886. BDAwx
I don't think Bermuda has ever been hit by a storm that was a cat 5 at some point, let alone being hit by a storm while at cat 5 strength. I'm sure being hit by a cat5 anywhere would be disastrous, but being on an island in the middle of the Atlantic, with an airport 5 feet above sea level, and a coral reef system that is nearly in-navigable in seas greater than 5 feet - if we needed outside aid we would have to wait days to get it.
I know that we can get through a minimal cat 3 storm without help... but a cat 5? I'm not quite sure about that - the cat 3 thing was pushing it. I remember the mad rush to get supplies lasting until after tropical storm force winds had begun during Fabian.

My biggest fear is that Bermudians are getting a little complacent about their preparations after Colin, Danielle, and Fiona. A lot of people don't realize that we are lucky to get off without a scratch from them, maybe our luck will continue?
Member Since: August 3, 2009 Posts: 51 Comments: 543
Given this plot, same as the one a bit ago, one has to assume a TC starting in the neighborhood of 40W and 35 N made landfall in the GoM. Whiskey Tango Foxtrot? (Anyone know how the heck that happened?)

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1884. beell
180 hr guess.
(so if time is money, this opinion must be very valuable...)

Pretty interesting visual of the 180hr/GFS12Z jet stream loop. Mostly zonal-but fairly far south and "brisk".

Strong (protective) ridging over the SE, the GOM, and the Caribbean west of the southward diving split of the jet near the SE coast.

I will assume the weakness will not magically heal itself ala CMC and other models showing same-leaving Igor a slow creep up into the westerlies. Still a problem for Bermuda.
300mb loop
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1883. hydrus
Igor is going to be a CAT-65863834- Storm surge-76586- Windspeed-8765686. PFFFFFFFFFFFFFFFT..........AAAAAAHHHHHHHHH!!!!!:) :) Good Evening to all posting tonight on Weather Underground..An absolutely stellar day here on the Cumberland Plateau- 65 Degrees.....Wind out of the north at 10 mph with very low humidity. I-GOR is looking more impressive by the minute...
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Quoting CybrTeddy:
I'm going out on a limb and saying this is Juliet now.


I thought it was JULIA.
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Quoting CybrTeddy:
My bad.. Julia*

Got my 'J's confused.


Hey at least thats closer than Earl/Igor!
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A of of limb climbers this evening.
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If the NHC had taken storm surge forecasts out of the Saffir-Simpson Scale, as they should have done after 2005, more people might have evacuated before Ike. Katrina was a strong cat-3 at landfall with a "cat-5" surge, and Ike was a strong cat-2 with a "cat-4" surge. Size of storm and shape of coastline together can be as important as windspeed in many situations. I hope the NHC and other organizations will emphasize this and completely uncouple surge forecasts from the SSS.
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Quoting AWeatherLover:


Link


That's an awesome resource! Thanks!
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Quoting Gearsts:
Theres a better spin now finally.

It actually has had a descent spin for a while now. We probably could finally see a depression tomorrow.

Member Since: August 9, 2009 Posts: 10 Comments: 5070
well Igor seems destined to be the 1st cat five of 2010 I think it's really eerie that 7 years and two days ago ago Isabel was in almost the exact same spot at almost the exact same intensity and a fairly similar forecast I really hope that is where the similarities end.
Member Since: March 29, 2008 Posts: 0 Comments: 2374
My bad.. Julia*

Got my 'J's confused.
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lol juilet u mean julia
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Quoting WeatherMSK:
I thought it was Julia?

It is, haha.
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Anyone remember this ? This is why people in the central and western Caribbean need to keep a close eye on 92L. Where it is now anything is possible.

It formed on the morning of August 25, 2008, about 260 miles (420 km) southeast of Port-au-Prince, Haiti, and rapidly strengthened into a tropical storm that afternoon and into a hurricane early on August 26. Later that day it made landfall near the Haitian town of Jacmel. It inundated Jamaica and ravaged Western Cuba and then steadily moved across the Gulf of Mexico.[3][4]
Member Since: October 9, 2008 Posts: 0 Comments: 8418
Quoting WeatherMSK:
I thought it was Julia?
LOL, it is.
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I thought it was Julia?
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Quoting CybrTeddy:
I'm going out on a limb and saying this is Juliet now.

Not really a limb, but I agree. :)
Member Since: September 2, 2009 Posts: 130 Comments: 21194
I'm going out on a limb and saying this is Juliet now.

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based on Doorman's photo our feature in the Caribbean is truly getting its act together.
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Quoting alaina1085:
Wassup blog addicts...

Igor's a beast!


Yes he is, reminds me of my younger days lol
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1864. leo305
Quoting WeatherNerdPR:
If there's one thing I like about TWC, it's the 3D Storm view they show. That is just epic.


I think it makes the hurricanes look smaller than they actually are
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Still cant get over how Igor is already a cat 4 and maybe a cat 5.
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1862. angiest
Quoting jrweatherman:
For those who want to compare Igor to Ike in track, read the verbiage from Ike's Discussion #1. It is all westward biased. I don't see why we are comparing to Ike.


THE
DEPRESSION IS LOCATED SOUTH OF A STRONG SUBTROPICAL RIDGE WHICH IS
BUILDING AND EXPANDING WESTWARD ACCORDING TO MOST OF THE GLOBAL
MODELS. THIS PATTERN CALLS FOR A GENERAL WEST TO WEST-NORTHWEST
TRACK FOR THE NEXT 2 TO 3 DAYS. THEREFATER...AS THE HIGH BUILDS
FARTHER WESTWARD...THE CYCLONE COULD TURN MORE TO THE WEST. THE
OFFICIAL FORECAST IS IN THE MIDDLE OF THE GUIDANCE ENVELOPE AND
VERY CLOSE TO THE MODEL CONSENSUS. SINCE THE TRACK GUIDANCE IS
RATHER TIGHT...THE FORECAST CONFIDENCE IS RELATIVELY HIGH.



I think the "comparison" is that Ike went well west of forecast, not that Igor follows the same path.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
Wassup blog addicts...

Igor's a beast!
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1859. Walshy
Quoting TropicalAnalystwx13:
I'm going on a limb and saying that Igor is currently a Category 5 Hurricane.


Im thinking the same thing. If only it were further west, we could get a plane in there to confirm it.

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Teddy that storm reminds me of Mitch when he was marching through the Caribbean.
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For those who want to compare Igor to Ike in track, read the verbiage from Ike's Discussion #1. It is all westward biased. I don't see why we are comparing to Ike.


THE
DEPRESSION IS LOCATED SOUTH OF A STRONG SUBTROPICAL RIDGE WHICH IS
BUILDING AND EXPANDING WESTWARD ACCORDING TO MOST OF THE GLOBAL
MODELS. THIS PATTERN CALLS FOR A GENERAL WEST TO WEST-NORTHWEST
TRACK FOR THE NEXT 2 TO 3 DAYS. THEREFATER...AS THE HIGH BUILDS
FARTHER WESTWARD...THE CYCLONE COULD TURN MORE TO THE WEST. THE
OFFICIAL FORECAST IS IN THE MIDDLE OF THE GUIDANCE ENVELOPE AND
VERY CLOSE TO THE MODEL CONSENSUS. SINCE THE TRACK GUIDANCE IS
RATHER TIGHT...THE FORECAST CONFIDENCE IS RELATIVELY HIGH.

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If there's one thing I like about TWC, it's the 3D Storm view they show. That is just epic.
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1855. MZT
Quoting mbjjm:
92L just watch for the "mysterious" evening collapse later
That was yesterday's head fake ... maybe now that it's over warmer water, it will not have the nightly POOF again...
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1854. angiest
Quoting MZT:
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!


I know when he was over Cuba people on here were saying no way he comes to Texas. From Cuba he took a similar track to the 1900 storm. *That* nugget wasn't lost on me.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
1825:

I think it will be very close to cat5, if not cat5 by 11p.m.

It may also peak again near 57W, as there is a 165kts+ max intensity predictor there, and no particular reason to assume atmospheric conditions will be much different, if any different, by the time the storm gets there...

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Quoting btwntx08:

ummm at this time yesterday convection was waning now look its building convection when the last few days it didnt
Look's like 92L is shrugging-off the bad Gaston mojo and getting its act together....if the central pressure drops a couple more mbar it will be off to the races.
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FSU historical track probabilities put Igor's position at a 15% probability of landfall anywhere on the east coast.



PR has, apparently, less than 5% less than 1% chance of landfall, going by storms of the past:


GoM, very little chance of Igor. But 92 L's position (as we all intuitively know) gives it a decent chance. ~40%, but declining if it moves straight west. NW, well, increasing chances:
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Miami what happened to our canes yesterday?

As for Td12 its getting its act together pretty fast right now. As for Igor, I have my eyes on him seriously in both the realm of work, which means we will be busy and in the realm of personal safety.
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1849. Gearsts
Quoting TropicalAnalystwx13:
I'm going on a limb and saying that Igor is currently a Category 5 Hurricane.
150mph i think
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i wonder what Igor's rating would be in just its pressure drop over 24 hours, wow the bottom fell out of the barometer.
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1847. Walshy
This track is interesting.



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I'm going on a limb and saying that Igor is currently a Category 5 Hurricane.
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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.