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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Wow looking at satellite Igor looks to be about 17.6 now trending south of west. Although I have notice they tend to get a little erratic when they are about to change direction. That said he is moving just like Andrew before he reached S, Fl..Which saved N. Dade County at the expense of pour S. Dade.
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Quoting DestinJeff:


biannular.

experimenting.....college.

bi.

annular.


Oh, I'm thinking things have changed since I was last in school back in the *0's :)
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Here we go again:

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3342. Relix
LOL @ Igor saying *get out of my way* to the next forecast point XD!
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3341. JLPR2
Quoting atmoaggie:
Based on the tracks of all of our historical records, a hurricane in Igor's current position has a less that 1% chance of landfall on PR. (This does not include brushing by PR, only landfall)



This is not a dynamical analysis, statistics based on our past storms' tracks.


if it were more to the SW I would be worried. XD
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3340. WXTXN
NHC says no well defined circulation at 92L but I see a pretty obvious circulation on the shortwave ir floater that they supply. Any explanations out there...?
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3337. FLDART1
Quoting PSLFLCaneVet:
Good evening Keeper. Is that a good-sized earthquake at the southern end of the Mid-Atlantic Ridge?
5.1
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3336. Levi32
Quoting Hurricanes101:
Igor has been moving just south of due west for about 4 hours now

also the 11pm advisory was .1 lower than it was at 5, may not mean anything overall, but it will be interesting to see if it still continues to move that way

no models even suggested any sort of move just south of west


Exactly....which is why although it's a small deviation it is interesting. I love it when the insanely tight-packed 6-hour model forecasts are all off by 20-30 miles.
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Time to say good night. I am still concerned that IGOR will likely come in farther South then models and predictions are currntly saying. I hope I am wrong but the WV pattern says different to me.

Link
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3333. KEEPEROFTHEGATE (Mod)
Quoting PSLFLCaneVet:
Good evening Keeper. Is that a good-sized earthquake at the southern end of the Mid-Atlantic Ridge?
5.1
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3332. FLDART1
Quoting StormJunkie:


Evening Dart, good to see you around here.

While this may be true...And I agree there is still plenty of time with Igor. (I assume that's what we are referring to.) I think this is the same mentality of Mrs Lyda Ann Hunkerdown that cost lives on the Bolivar Peninsula. I also think some arguments could be made that this way of thinking may have also cost some lives during Katrina as well.
SJ, I do believe sir, that we were witness that type of mentality in action; first hand. Good to see you and and little man...Ever Vigilant...
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Quoting hdominguez:
Hello,

What about that whooper right on the boundary of Mali and Burkina-Faso, still to emerge from Africa? http://www.ssd.noaa.gov/eumet/eatl/wv-l.jpg

Cheers

HDLink
Link Its Mali in africa and its a doosie
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Quoting sunlinepr:
Igor 17.6N 47.8 W 150 mph. We need him to move at least to 20 N Worst situation....

Based on the tracks of all of our historical records, a hurricane in Igor's current position has a less that 1% chance of landfall on PR. (This does not include brushing by PR, only landfall)



This is not a dynamical analysis, statistics based on our past storms' tracks.
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3328. KEEPEROFTHEGATE (Mod)
Quoting DestinJeff:


OMG! Is that quake rectangular?
its a square
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3327. JLPR2
LOL
Pass close to PR 500miles to the NE, LOL!
I laughed out loud, why does that statement sound funny? :P

I think the weather I just saw should consider another job. XD
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Quoting KEEPEROFTHEGATE:
Good evening Keeper. Is that a good-sized earthquake at the southern end of the Mid-Atlantic Ridge?
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Quoting RyanFSU:
I suggested two days ago that nothing would stop Igor from becoming a Category 5 and I am a little befuddled that the NHC was so conservative in their forecast. With the almost perfect atmospheric conditions and warm SSTs, Igor was destined to approach its Maximum Potential Intensity (MPI) relatively quickly.

Its explosive development is also an indictment of the dynamical models' intensity predictions which haven't been particular good. Even the overambitious HWRF and GFDL grossly underestimated the RI just 12-18 hours ago.

I remember you saying that and the comments too. NHC is encumbered. So are the forecasters. The NHC can't always do the obvious. Hint noaa.gov we know what gov stands for.
Member Since: April 9, 2010 Posts: 5 Comments: 5001


Doesn't look like it is giving up so easy tonight. Still holding convection and consolidating at the "COC"
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Igor has been moving just south of due west for about 4 hours now

also the 11pm advisory was .1 lower than it was at 5, may not mean anything overall, but it will be interesting to see if it still continues to move that way

no models even suggested any sort of move just south of west
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Quoting PanhandleChuck:
I firmly believe that the GOM will be an area that a back yard Ninja will form within the next two weeks... It ain't gonna be pretty for whom ever gets hit with it


Just something waiting to happen, really...
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3320. pottery
Quoting RyanFSU:
I suggested two days ago that nothing would stop Igor from becoming a Category 5 and I am a little befuddled that the NHC was so conservative in their forecast. With the almost perfect atmospheric conditions and warm SSTs, Igor was destined to approach its Maximum Potential Intensity (MPI) relatively quickly.

Its explosive development is also an indictment of the dynamical models' intensity predictions which haven't been particular good. Even the overambitious HWRF and GFDL grossly underestimated the RI just 12-18 hours ago.

Back briefly..

What is your take on the steering for Igor in the coming days?
There seems to be some ambiguity with the Official track...
Member Since: October 24, 2005 Posts: 0 Comments: 24646
Night tc. Sleep well.
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Hello,

What about that whooper right on the boundary of Mali and Burkina-Faso, still to emerge from Africa? http://www.ssd.noaa.gov/eumet/eatl/wv-l.jpg

Cheers

HDLink
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Quoting BahaHurican:
Hey, zoo. To me, the fact that they even mention the possibility means that it's likely enough to keep me watching. I'm still hoping we see that recurve (N) before 70W, but I'm not betting my life on it right now.... expecting a whole LOT more drama about Igor before it's all over...


You definitely need to keep an eye out. You stick out more than we do! lol
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3314. KEEPEROFTHEGATE (Mod)
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goodnight all.
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Quoting AussieStorm:
Have a look at how Igor is effecting the environment around him and even as far away as 30N


Click image for loop.
Good evening, Aussie. Glad to have you back on. (evening/night here: EDT, U.S.)
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I firmly believe that the GOM will be an area that a back yard Ninja will form within the next two weeks... It ain't gonna be pretty for whom ever gets hit with it
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dont be sry if this thing fires up could be a threat to us so pay atttention
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Quoting PrivateIdaho:
Wow! Is this a weather related post?


Yes. >_>
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Quoting Hurricanes101:


we are currently 5 storms behind 2005, which was up to Ophelia at this point, Phillippe formed on the 17th

looking back at 6 of the busiest seasons so far and seeing where they were on this date

1933: 14 named storms, 7 Hurricanes, 4 Major Hurricanes, 15th storm formed on Sept 16th (21 storms total that season)
1969: 7 named storms, 5 Hurricanes, 4 Major Hurricanes, 8th storm formed on Sept 14th (18 storms total that season)
1995: 13 named storms, 6 Hurricanes, 2 Major Hurricanes, 14th storm formed on Sept 26th (19 storms total that season)
2004: 10 named storms, 6 Hurricanes, 4 Major Hurricanes, 11th storm formed on Sept 16th (15 storms total that season)
2005: 15 named storms, 8 Hurricanes, 4 Major Hurricanes, 16th storm formed on Sept 17th (28 storms total that season)
2008: 10 named storms, 5 Hurricanes, 3 Major Hurricanes, 11th storm formed on Sept 25th (16 storms total that season)

2010: 10 named storms, 4 Hurricanes, 3 Major Hurricanes,


I'm still going with 17 total for this year
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Quoting Hurricanes101:


we are currently 5 storms behind 2005, which was up to Ophelia at this point, Phillippe formed on the 17th

looking back at 6 of the busiest seasons so far and seeing where they were on this date

1933: 14 named storms, 7 Hurricanes, 4 Major Hurricanes, 15th storm formed on Sept 16th (21 storms total that season)
1969: 7 named storms, 5 Hurricanes, 4 Major Hurricanes, 8th storm formed on Sept 14th (18 storms total that season)
1995: 13 named storms, 6 Hurricanes, 2 Major Hurricanes, 14th storm formed on Sept 26th (19 storms total that season)
2004: 10 named storms, 6 Hurricanes, 4 Major Hurricanes, 11th storm formed on Sept 16th (15 storms total that season)
2005: 15 named storms, 8 Hurricanes, 4 Major Hurricanes, 16th storm formed on Sept 17th (28 storms total that season)
2008: 10 named storms, 5 Hurricanes, 3 Major Hurricanes, 11th storm formed on Sept 25th (16 storms total that season)

2010: 10 named storms, 4 Hurricanes, 3 Major Hurricanes,


We may very well pass the majors from previous years. Such a long way to go.
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Quoting DestinJeff:


Silly, Igor isn't in college.


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dude recon found sw winds means some kind of llc
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Quoting zoomiami:


Yep -- wow

The blog has been going so fast, that its hard to post and read.

Igor is not set in stone yet obviously, but it is a long way away. Needs to be watched.
Hey, zoo. To me, the fact that they even mention the possibility means that it's likely enough to keep me watching. I'm still hoping we see that recurve (N) before 70W, but I'm not betting my life on it right now.... expecting a whole LOT more drama about Igor before it's all over...
Member Since: October 25, 2005 Posts: 19 Comments: 22561
Quoting JLPR2:
Jeez, news weather man are such wishcasters LOL!
I just saw one say that Igor was heading to the NE Caribbean moving straight west, not to be alarmed, but vigilant and he didn't even show the NHC cone. >:| WTH?


Don't you love how the room reacts to these storms a week before it gets close to anything!!...lol
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3300. Levi32
Quoting DestinJeff:


I wonder if there is a bridge like that anywhere?

Levi?


Bridge?
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Good night everyone!

Season total ACE


01L (Alex): 6.7825
03L (Bonnie): 0.3675
04L (Colin): 1.9450
06L (Danielle): 21.7950
07L (Earl): 27.7750
08L (Fiona): 2.9400
09L (Gaston): 0.3675
10L (Hermine): 1.2725
11L (Igor): 7.1050
12L (Julia): 0.1225
--------------------------------------
Total: 70.4725
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting wjdow:


how did you get so arrogant. of course they're going to kill somebody someday, because they're making life and death decisions, unlike you who does what? sorry, but quit already.


Now here is an example of some soul searching questions. We should stop and ponder them and make application where necessary. Poor RecordSeason got fubared by it's simplicity.

I give it a 7.5, mainly for the "unlike you who does what"? part.
Member Since: April 9, 2010 Posts: 5 Comments: 5001
Quoting KoritheMan:


They're fantastic ACE generators. Mayhaps that's the source of said fascination with annulars?
Wow! Is this a weather related post?
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Igor is not annular, but may have similar characteristics. He always had an eastern outflow channel present during his RI stage today, so in my opinion he wasn't annular. Extreme, Igor could definitely become a category five hurricane in the 24-36 hour timeframe, but not before then, he has peaked out right now, and after the EWRC he will peak again.
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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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