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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My theory with 92L,:

Its like, water too hot, ouch, ooh, getting burned, help me! Hey, maybe tropical systems don't like touching hot water just like humans don't like to put their hand on a burning stove!

Just Kidding. I really want to know why 92L hasn't developed yet. I am glad it hasn't, but I am always a "why" person, I want explanations.
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1494. sngalla
Thanks to you, too, Fiscal for answering my ?.
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If I were the NHC I would be considering 150mph right now. The 2 meso-vortices and the almost perfect organisation of the storm certainly merit it. However the Southern Section of the Storm certainly doesn't do it any favours - its clearly the weakest part of the storm.
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1492. scott39
Its hard to tell where 92Ls coc is.
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Quoting CosmicEvents:
Over at TWC, they're currently playing "short straw" to see who gets the Bermuda assignment.


bet they think about it.
Member Since: August 23, 2008 Posts: 0 Comments: 1918
92L unorganzined mess right now. drifting. maybe mid week
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Cantu5977, thanks for that beautiful picture. But, to my unprofessional eye, it looks like the eye is at 13sumthingN....like it has wobbled SOUTH again????? If so, am not liking that at all. Igor sure is getting big and is a beautiful storm. Hope it stays in the ocean and does not make landfall anywhere.
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Quoting BahaHurican:
What r numbers looking like now?

Jun-1
Jul-1
Aug-4
Sep-4 [and counting, maybe as many as 4 more]
Oct- [another 4?]
Nov- [1 or 2?]
[Dec- anything is possible with the late start]

Currently we are at 10-4-3, with another 8 - 10 NS not out of the running, at least potentially. If we have a couple more CV storms before that part of the season ends, we may see the 200+ ACE after all.

Hmmmm....


If we get 8 storms in September, that'll tie the record as the most September storms for the Atlantic, tying with 1998, 2002, and 2007.
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Quoting anyotherliestotell:
there is absolutely NO chance Igor will hit Florida. NONE.


Proof? That's a very bold statement. There's a chance for anything right now.
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What r numbers looking like now?

Jun-1
Jul-1
Aug-4
Sep-4 [and counting, maybe as many as 4 more]
Oct- [another 4?]
Nov- [1 or 2?]
[Dec- anything is possible with the late start]

Currently we are at 10-4-3, with another 8 - 10 NS not out of the running, at least potentially. If we have a couple more CV storms before that part of the season ends, we may see the 200+ ACE after all.

Hmmmm....
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1485. NRAamy
#1464.....hahahahahahahaha!!!!!


:)
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Quoting BahaHurican:
On the models and accuracy:

Seems to me nobody's arguing the 72hrs out... pple are basically ignoring that in their discussions of model accuracy. Does this mean we are taking that level of accuracy for granted these days? With a storm like Igor that 3 day forecast seems almost a "given".

The big argument here is always nowadays about the 4 - 7 [or even 6 - 10] day forecast. The big divergence with Igor is coming AFTER we enter the 4-day forecast range. Since not even NHC reposes much faith in their track errors at that point [500 miles is the difference between Mayaguana and Abaco, almost the entire length of the Bahamas, in fact] I dunno why we are even arguing about it. I agree with StormW and others like him who are looking at the WV for the last 12 hrs and observing realtime trends. I think we get a better idea of what could happen past that 3-day forecast period. For example, what's to see on the WV loop for the CONUS today? Anything out there to add oomph to the trough which will likely turn Igor NW, but may not be enough to recurve it fully before 70W?

And for those of u who think we "don't need to worry" and that because Earl paralleled the Bahamas far enough east to minimize effects here we should not pay attention to Igor, get this: every, EVERY system is different. The storm itself is different. The synoptic pattern is different, and even small differences in either can result in track differences that currently allow for potential impacts to locations from the NE Antilles/PR to Nova Scotia. WE ARE TOO FAR OUT FROM A RELIABLE FORECAST RIGHT NOW for anybody to be "ruling out" potentialities beyond that.



E X C E L L E N T!
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Have you guys noticed that 92L has been cursed this year?

92L in June: We were all sure that was going to develop, it was an impressive African tropical wave that was sure to become one of the farthest east June tropical cyclones in the Atlantic. But then, it kept deciding not to develop, and when it finally got around to developing deep convection, it got sheared apart.

92L in July: tropical wave fragment leftover from the wave that became Colin. After finally organizing in the western Caribbean, landfall with Yucatan and Mexico killed it.

92L in September (today): Once again, we are sure it should develop, but it decides to be wishy-washy, and won't develop. Will the curse of 92L hold?
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1482. sngalla
Quoting MiamiHurricanes09:
As of 2:30pm EDT, the NHC stated it was 20 nautical miles in diameter.


Thanks MiamiHurricane09!
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1481. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15603
1480. Max1023
By doughnut I mean eyewall. On Dvorak it looks like a doughnut in an intense system.
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Quoting anyotherliestotell:
there is absolutely NO chance Igor will hit Florida. NONE.
would not say that there is always a chance small but a chance
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Quoting Canesinlowplaces:
There's certainly enough heat in the water.

At what point do the westerlies start kicking in in the GOM - like where they shot Wilma east off the Yucatan Pen.? Is that in Oct?

Yep, in my experience, October=Wilma. Nasty storm!
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Quoting sngalla:
I may have missed it, but does anyone know the diameter of Igor's eye?
As of 2:30pm EDT, the NHC stated it was 20 nautical miles in diameter.
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Those Igor satellite images look like sawblades. I'm scared of power saws, and I'd be scared of this if I was anywhere close to its path.
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1474. Fiscal
Quoting sngalla:
I may have missed it, but does anyone know the diameter of Igor's eye?


The last NHC update had it at 20 NMI.
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But I looked at past computer models for Isabel and they intially had it going out to sea and they trended further west. So how are the steering mechanims for Igor different than Isabel?
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1471. sngalla
I may have missed it, but does anyone know the diameter of Igor's eye?
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#1435 BahaHurican

Excellent post
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Quoting kimoskee:


What exactly is this blob doing?

I'm very thankful that it hasn't developed but I really wish it would just disipate already. I know that's not likely to happen but can't stand the wishy-washy systems... I'm a low, I'm a low. I'm going away. I'm a low, I'm almost a depression, no wait a minute, changed my mind, I'm a low, no I'm a wave.... on and on and on... Yes I know... that's the weather folks, unpredictable...


LOL! I hate 92L too! Make up your mind, and quit reading shakespeare "to be or not to be, that is the question." From now on, I am classifying disturbances like 92L as Shakesperean tropical disturbances.
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Quoting NCHurricane2009:


Isn't that Felix 2007 you posted? I am really good at memorizing storm images of storms I have recorded, freaks myself out.

Is that Felix 2007?


Correct it was a really nice looking storm..
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Ughhh, double post. Here's the rainbow image, lol:

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Quoting troy1993:
MiamiHurricane09 do you think its possible we could see a track similar to Hurricane Isabel or the 1933 Hurricane that hit Virginia?
It's possible...not very likely though.
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Over at TWC, they're currently playing "short straw" to see who gets the Bermuda assignment.
Member Since: August 3, 2005 Posts: 10 Comments: 5458
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Quoting Cantu5977:


lol I think he is speaking of this donut....


Isn't that Felix 2007 you posted? I am really good at memorizing storm images of storms I have recorded, freaks myself out.

Is that Felix 2007?
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Intense eyewall. Hot tower firing along the SE semicircle.

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Quoting TexasHurricane:
92L



What exactly is this blob doing?

I'm very thankful that it hasn't developed but I really wish it would just disipate already. I know that's not likely to happen but can't stand the wishy-washy systems... I'm a low, I'm a low. I'm going away. I'm a low, I'm almost a depression, no wait a minute, changed my mind, I'm a low, no I'm a wave.... on and on and on... Yes I know... that's the weather folks, unpredictable...
Member Since: August 17, 2008 Posts: 0 Comments: 672
Quoting CybrTeddy:
If the NHC goes with the ADT again it is possible they will raise it to 145 mph.

CI# /Pressure/ Vmax
6.4 / 939.6mb/124.6kt



Kinda looks like a Cat 5 IMO.
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1458. Vero1
Quoting 954FtLCane:

Ok Dont mean to sound like a newbie but where exactly is the SW Atlantic?


Left of the "High Seas"

Member Since: Posts: Comments:
Quoting BahaHurican:
On the models and accuracy:

Seems to me nobody's arguing the 72hrs out... pple are basically ignoring that in their discussions of model accuracy. Does this mean we are taking that level of accuracy for granted these days? With a storm like Igor that 3 day forecast seems almost a "given".

The big argument here is always nowadays about the 4 - 7 [or even 6 - 10] day forecast. The big divergence with Igor is coming AFTER we enter the 4-day forecast range. Since not even NHC reposes much faith in their track errors at that point [500 miles is the difference between Mayaguana and Abaco, almost the entire length of the Bahamas, in fact] I dunno why we are even arguing about it. I agree with StormW and others like him who are looking at the WV for the last 12 hrs and observing realtime trends. I think we get a better idea of what could happen past that 3-day forecast period. For example, what's to see on the WV loop for the CONUS today? Anything out there to add oomph to the trough which will likely turn Igor NW, but may not be enough to recurve it fully before 70W?

And for those of u who think we "don't need to worry" and that because Earl paralleled the Bahamas far enough east to minimize effects here we should not pay attention to Igor, get this: every, EVERY system is different. The storm itself is different. The synoptic pattern is different, and even small differences in either can result in track differences that currently allow for potential impacts to locations from the NE Antilles/PR to Nova Scotia. WE ARE TOO FAR OUT FROM A RELIABLE FORECAST RIGHT NOW for anybody to be "ruling out" potentialities beyond that.
VERY WELL PUT !!!!!!
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Quoting MiamiHurricanes09:
Oh, I see what he means. We currently have a white donut then.

Notice how the darker greys with the white donut form a perfect hurricane symbol :O
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By chance if we had a conus landing of Igor in Fla, how long would it take for it to go the 2200 miles from its present location to Miami? Would 7 more days be close?
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MiamiHurricane09 do you think its possible we could see a track similar to Hurricane Isabel or the 1933 Hurricane that hit Virginia?
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Local Miami met stating Igor needs to be watched by bermuda and mid atlantic states.. I Think we need to all watch it.
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Quoting MiamiHurricanes09:
Huh? What are these donuts you're speaking about? Lol.


lol I think he is speaking of this donut....
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Quoting Levi32:
While Igor is stealing the show, the pattern will be turning towards one that is favorable for the SW Atlantic Basin to light up during the end of September, and we're starting to see results and hints from some of the models. The CMC is consistently showing very low pressures in the Caribbean and GOM in 15 days, and the GFS operational and ensemble mean has been saying there should be a hurricane hitting the US in 2 weeks or so.

Just hints of things to come, and support for the idea that the SW Atlantic will start picking up the slack and take the torch as the Cape Verde season winds down.



Could storm impacts be "delayed but not denied" just like the active season that was widely questioned back in August? Unfortunately, a lot of potential for that!
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Quoting MZT:
Have to admit I've always had trouble making sense of the Dvorak images. This boils it down to it's essentials. Heh
Oh, I see what he means. We currently have a white donut then.

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Quoting MiamiHurricanes09:
Huh? What are these donuts you're speaking about? Lol.
I believe he is talking about convective rings on dvorak imagery.
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Quoting MiamiHurricanes09:
Dolphins won! Nice.



And just as the Dolphins win, pinwheel eye showing in Igor (as you are showing in that image). Hopefully the dolphins down under in the ocean Igor are not going to lose!

(Disclaimer: I am not a marine biologist, so technically I don't know if there are real dolphins in that part of the ocean. Just a joke, LOL. Don't you love disclaimers?)
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Quoting StormW:


Levi,
you wasn't sposed to let our secret out!

Ok Dont mean to sound like a newbie but where exactly is the SW Atlantic?
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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.