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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FTR, Isabel's track. Be interested to see an overlay of their--Isabel and Igor-- respective tracks thus far


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Since he is stuck in the middle of the Atlantic and can't match the track of the name that he replaced, Igor seems determined to surpass Ivan's intensity! Props to the Euro for seeing the RI potential and sticking to it. Guess we'll have to see just how accurate the ECMWF really was on that. There was one run where it showed a 905 mb storm. I scoffed to myself at that, but if Igor's timing on EWRC is just right, it may well be possible to make a run at that kind of intensity. That would be historic.
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Wow. Anyone know what the strongest Hurricane at Earl's position was?
Member Since: June 9, 2007 Posts: 4 Comments: 15950
People in Bermuda might want to pay attention to Igor. GFS 6z run has Igor taking a vacation on Bermuda...

Member Since: September 21, 2005 Posts: 2 Comments: 310
Quoting MiamiHurricanes09:
Absolutely beautiful.



Watch out 09, he may wink at ya :)
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HH position update

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2038. xcool






Member Since: September 26, 2009 Posts: 2 Comments: 15684
.
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Man, between Danielle, Earl and now Igor, there have been some simply gorgeous storms this year. Beautiful displayes of the awesome power of nature, and thankfully relatively harmless so far too.
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Absolutely beautiful.

Member Since: September 2, 2009 Posts: 130 Comments: 21194
Is Igor set to go to Cat5 ?
The shear is expected to weaken to just 5 knots.
Member Since: August 29, 2009 Posts: 12 Comments: 483
Quoting: Patrap 10:44 PM GMT on September 12, 2010 Hide this comment.
I was I mile or 2 west of this video as we went thru Elena in 85 in Long Beach,Mississippi.

EXCELENT VIDEO
Member Since: August 2, 2010 Posts: 21 Comments: 9882
Impressive training of systems.

**FULL IMAGE

Member Since: June 9, 2007 Posts: 4 Comments: 15950
Quoting kmanislander:


See correction for NW to read NE
I figured that is what you meant because tilted could not be NW to SW or that would be straight. LOL
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2029. Patrap
Quoting weathermancer:


Wow. incredible!
Do you also have footage of the eyewall winds as they increase?


Negative..thats NOT my video,,but we could hear the backside winds a coming a full 2-minutes before they hit. We were near the SEABEE Base at the end of Pass road.
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2028. Max1023


Over 28 degree SSTs.

What will we see in 72 hours?
Member Since: July 22, 2008 Posts: 1 Comments: 286
Quoting Patrap:



Just a lil wink dats all.

The dog of mine growled alil though.

Go figure,


Good dog!
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Quoting Stormchaser2007:
It would be pretty crazy if the T-numbers went up to 7.0
The Raw T# is at 6.8. The CI# is at 6.6.

2010SEP12 221500 6.6 934.2/ +2.0 /129.6 6.6 6.8 6.8 3.2T/18hr OFF OFF 16.74 -70.44 EYE 25 IR 17.66 46.79 COMBO
Member Since: September 2, 2009 Posts: 130 Comments: 21194
2025. Patrap
IGOR

Rainbow

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Quoting Patrap:
I was I mile or 2 west of this video as we went thru Elena in 85 in Long Beach,Mississippi.

vmax135 | December 25, 2008
Hurricane Elena's textbook eye moves over Biloxi, Mississippi on the morning of September 2, 1985.



Wow. incredible!
Do you also have footage of the eyewall winds as they increase?
Member Since: August 29, 2009 Posts: 12 Comments: 483
2023. txjac
OMG Pat ...that was amazing! Thank you
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2022. Titoxd
Quoting PcolaDan:
It would be Romero y Julia in the Spanish version, no? ;)


No, it's still Romeo :P
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2020. Patrap
Quoting doorman79:
Pat,

My ex didn't give you to much trouble today i hope!



Just a lil wink dats all.

The dog of mine growled alil though.

Go figure,
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Quoting kmanislander:


The last few satellite frames show the system going from being oriented from the SW to the NE in an elogated disorganized fashion to being more "upright" in the middle with a developing ball of convection. There is also evidence of good rotation near 16 / 73.

It still has work to do but there are signs of a change in the structure towards some development occurring.


Agreeed. The line of convergence rotated from nearly east west when 92L was over the southern Lesser Antilles to northeast southwest yesterday, to nearly north south today.

With the prevailing easterlies (trade winds) the North-South orientation is perpedicular...leading to stronger surface convergence, increased convection, and of course a higher likelihood of development.

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Quoting stormwatcherCI:
Thank you.


See correction for NW to read NE
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92L is definately South over water. Its center is broad and disorganized at this time. It almost looks like there are multiple circulations within a larger broad circulation.

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Quoting all4hurricanes:
I never trust what water temperatures are "supposed to support" epsilon formed in waters that shouldn't have supported a ts, Bertha rapidly intensified in water with heat potential that shouldn't have fueled her, Isabel became a 5 around that spot and 2003 didn't set Atlantic heat records, I say if Igor has winds of 160 then he's a five there really isn't much that we can do to predict him at this point


I think it has less to do with SSTs and more to do with whether or not atmospheric parameters are favorable. In Igor's case, the upper-level wind environment was anticyclonic, and very favorable for intensification, which mitigated the effects of the relatively shallow water in this area of the Atlantic.
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Quoting WeatherNerdPR:

Lauren? I thought it was Laura...
It's Lisa, Laura was 2008
Member Since: March 29, 2008 Posts: 0 Comments: 2377
Pat,

My ex didn't give you to much trouble today i hope!
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2013. Max1023
Quoting Stormchaser2007:
It would be pretty crazy if the T-numbers went up to 7.0


Looking at that 22:45 Dvorak I think they will. That is a solid ring of white with grey thrown in.
Member Since: July 22, 2008 Posts: 1 Comments: 286
Quoting weatherwatcher12:

Bad idea to tamper with nature, bad things will happen.


It's not nice to fool Mother Nature!
Member Since: August 27, 2006 Posts: 0 Comments: 249
Quoting WeatherNerdPR:

Lauren? I thought it was Laura...
Quoting KoritheMan:


Lauren? I think you mean Lisa...


Laura, Lisa, Lauren.

Its all the same. lol.
Member Since: July 6, 2010 Posts: 113 Comments: 32870
I never trust what water temperatures are "supposed to support" epsilon formed in waters that shouldn't have supported a ts, Bertha rapidly intensified in water with heat potential that shouldn't have fueled her, Isabel became a 5 around that spot and 2003 didn't set Atlantic heat records, I say if Igor has winds of 160 then he's a five there really isn't much that we can do to predict him at this point
Member Since: March 29, 2008 Posts: 0 Comments: 2377
It would be pretty crazy if the T-numbers went up to 7.0
Member Since: June 9, 2007 Posts: 4 Comments: 15950
Quoting txjac:
Simply amazing ..thanks for the answers and shame on you Kori ...lol


;)
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2007. Patrap
1984. MZT


I was I mile or 2 west of this video as we went thru Elena in 85 in Long Beach,Mississippi.

vmax135 | December 25, 2008
Hurricane Elena's textbook eye moves over Biloxi, Mississippi on the morning of September 2, 1985.

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Drak, the question becomes did she originally have a surface circulation already and was just waiting for timing before doing something. If we remember there was something of the system before and now its firing again. Doorman posted something that showed off the infrared on the storm and it appeared to have just such.

Kman thoughts on Igor and his track?
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Quoting TropicalAnalystwx13:
Classic La-Nina year...Slow start, active, active finish. We are no where near done however. We should have Karl or whatever the storm's name is by the end of the week. Laruen should be here by the beginning of next week.

TD 12 -> Julia

92L -> Karl, "K" storm

Wave behind TD12 -> Lauren


Lauren? I thought it was Laura...
Member Since: July 7, 2010 Posts: 0 Comments: 5725
Quoting doorman79:
Kman tought me last night. Basically, if a wave cannot close off a low before 63 degrees in the carribian, it will not form untill 75 west. Think thats right lol


Thanks
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2003. Max1023
Quoting RecordSeason:




\
If that's not a Category 5 I don't know what is.
Member Since: July 22, 2008 Posts: 1 Comments: 286
2002. txjac
Simply amazing ..thanks for the answers and shame on you Kori ...lol
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NW corrected to NE in my post 1978
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1999. Walshy
Quoting Drakoen:
92L seems to be firing some strong convection. Question is will it hold long enough to induce the formation of a surface circulation.



I agree. With Igor, it seems it has outflows of clouds on the north and south sides are fairly short or non existent compared to most major hurricanes. Now, I could be looking at the wrong maps, but does this mean Igor might have a chance of being an annular type storm?
Member Since: May 17, 2009 Posts: 2 Comments: 907
Quoting hydrus:
It was an attempt at humor...I am in a good mood today, but I hate cat food now. I read the ingredients on the can and there is no cat in it....They lied...


hehehe ;-D Good thing too or the cats wouldnt like it!
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Quoting TropicalAnalystwx13:
Classic La-Nina year...Slow start, active, active finish. We are no where near done however. We should have Karl or whatever the storm's name is by the end of the week. Laruen should be here by the beginning of next week.

TD 12 -> Julia

92L -> Karl, "K" storm

Wave behind TD12 -> Lauren



Lauren? I think you mean Lisa...
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Quoting weatherwatcher12:

The hh's are on their way in so we should know soon.


Yeah, I read that earlier that they were headed out this afternoon. Apperently more eveningtime. Good to hear. Definitely will watch the data coming in!
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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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