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 dmaddox:
i predict another special advisory by the NHC on Igor at the top of the hour classifying him Cat. 5!


Nothing supports an upgrade at the moment.
Member Since: June 9, 2007 Posts: 4 Comments: 15776
Quoting CybrTeddy:
Great scott..
CI# /Pressure/ Vmax
6.6 / 934.2mb/129.6kt


Final T# Adj T# Raw T#
6.6 6.7 6.7



150 mph????
Member Since: July 6, 2010 Posts: 113 Comments: 31415
2193. MZT
Aemeister12, yeah that looks like banding, doesn't it? This may be the night that 92L fools the skeptics.
Member Since: September 24, 2005 Posts: 0 Comments: 793
Great scott..
CI# /Pressure/ Vmax
6.6 / 934.2mb/129.6kt


Final T# Adj T# Raw T#
6.6 6.7 6.7

Member Since: July 8, 2005 Posts: 259 Comments: 23562
Quoting hunkerdown:
nasty and gross...go get a "real" pizza not a commercialized wanna be...
Yeah, Casola's for me, but you can say that's nasty and gross too.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Personally, If I was the forecaster(s) writing the TWO tonight, I would give 92L a 60% chance.
Member Since: July 6, 2010 Posts: 113 Comments: 31415
2189. xcool
btwntx08 cowboy nott going win lol
Member Since: September 26, 2009 Posts: 2 Comments: 15620
does it matter if igor is annular or not as far as path?
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2187. dmaddox
i predict another special advisory by the NHC on Igor at the top of the hour classifying him Cat. 5!
Member Since: May 5, 2007 Posts: 0 Comments: 445
TD 12 looks like it's becoming a tropical storm.

Member Since: August 9, 2009 Posts: 10 Comments: 4898
thank you StormW

instead of just bashing people like Jedkins did you actually explained it

and yes Igor is very close to annular
Member Since: March 10, 2010 Posts: 1 Comments: 7353
Quoting Stormchaser2007:
22:45

Extremely impressive



It'd be even more impressive if the whole thing was white.
Member Since: July 6, 2010 Posts: 113 Comments: 31415
Looking at Atlantic Cat 5s, I see that Isabel reached 915 mb at 21.5N, 54.8W. That is the lowest pressure ever observed in a hurricane outside the Gulf and Caribbean, I believe. Hugo reached 918 mb at 14.6N, 54.6W. There really aren't that many Cat 5 storms in the open Atlantic to choose from! Floyd officially never reached 5 (though in actuality, it probably did), and it hit 921 mb. Igor really has got Isabel's record in its sights. Props again to the ecmwf for seeing this.
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2181. Walshy
Quoting MZT:
I would not make comparisons between Igor and Gulf storms. Stick to ones like Isabel, Floyd, Andrew, etc. I'd say Dean, Emily and Felix are not good comparisons either since they went further south and attained max intensity in the Caribbean.


Agreed. Isabel is about the only comparable storm right now in terms of location and strength.
Member Since: May 17, 2009 Posts: 2 Comments: 904
Quoting Jedkins01:


No, category 5 does not mean annular. Wilma for example, lowest pressure in the Atlantic Basin...
sorry I know cat fives aren't annular I meant to put a comma in there somewhere
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2178. markot
storm looks 2nd trof is weakining,,,
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I will be back later.
Member Since: August 19, 2006 Posts: 0 Comments: 15707
Quoting GeoffreyWPB:
Pizza Hut or Papa John's tonight????
nasty and gross...go get a "real" pizza not a commercialized wanna be...
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Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting StormW:
I'm not 100% sold on that second trof yet:

LINK

Back in a few


You have been giving subtle hints all day on this. I noticed :)
Member Since: August 11, 2010 Posts: 0 Comments: 895
Quoting Jedkins01:



gosh what is it with people in here and annular hurricanes? They are very rare, just because Igor is very intense and well organized does not make in annular. Dang.


large eye, strong convection around the center and very little banding

trust me we are not just throwing the word out there this time
Member Since: March 10, 2010 Posts: 1 Comments: 7353
22:45

Extremely impressive

Member Since: June 9, 2007 Posts: 4 Comments: 15776
Quoting RMM34667:


Here is West Pasco Florida you can get fresh Crispy Cremes at Walgreens.. go figure..
fresh Krispy Kremes, or "Hot Donuts Now" can only be gotten at an actual Krispy Kreme locations.
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1/3 trof's are out of the way. Igor destroyed it.

Storm says he is not sold on the 2nd trof.

That leaves one more before "Uh-Oh"
Member Since: July 6, 2010 Posts: 113 Comments: 31415
Quoting TexasHurricane:
Looks like it may be shifting more north...?


That can't be good.
Member Since: August 9, 2009 Posts: 10 Comments: 4898
Panoramic caravan...

Member Since: August 2, 2010 Posts: 21 Comments: 9690
Quoting Max1023:
I think the NHC is waiting until 11 hoping that Igor will weaken a bit so they don't have to call it a 5. (I'm Not really serious)


why would the NHC hope for anything, Igor is in the middle of nowhere
Member Since: March 10, 2010 Posts: 1 Comments: 7353
I'm just going to say the word "annular" too since that seems to be the word of the day now.
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Quoting TexasHurricane:
Looks like it may be shifting more north...?



Models are unreliable before a system develops a closed low. I wouldn't pay too much attention to those runs.
Member Since: August 19, 2006 Posts: 0 Comments: 15707
Quoting futuremet:
Igor will positively be the Atlantic's first category five Hurricane in three years...


We'll see.

Member Since: June 9, 2007 Posts: 4 Comments: 15776
2163. Walshy
Quoting Jedkins01:



gosh what is it with people in here and annular hurricanes? They are very rare, just because Igor is very intense and well organized does not make in annular. Dang.


Because, take a look at Igor on the top of the page from Masters. CAT2 with good banding, now we look toward a monster CAT4 with decreasing banding features.
Member Since: May 17, 2009 Posts: 2 Comments: 904
2162. MZT
I would not make comparisons between Igor and Gulf storms. Stick to ones like Isabel, Floyd, Andrew, etc. I'd say Dean, Emily and Felix are not good comparisons either since they went further south and attained max intensity in the Caribbean.
Member Since: September 24, 2005 Posts: 0 Comments: 793
2161. Hhunter
92l not td but does have classic s shape and starting to build convection near likely core would be nice to get some recon, buoy, or ship report
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I think Igor could peak at a 160mph cat 5 huricane.Well that's just my take.
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Quoting RMM34667:


Here is West Pasco Florida you can get fresh Crispy Cremes at Walgreens.. go figure..


Here too, but they not hor and freshhhhhh like at the krispy shop.
Member Since: August 11, 2010 Posts: 0 Comments: 895
Quoting StormW:


It's very close.

Here's an excerpt from the definition (wiki)

Annular hurricanes are axisymmetric — symmetric along every radial axis, i.e. very circular in appearance. They lack the spiralform rainbands which are characteristic of typical tropical cyclones.




Hey, Storm, do yo think it's possible it could end up becoming annular?
Member Since: August 9, 2009 Posts: 10 Comments: 4898
Looks like it may be shifting more north...?

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Quoting futuremet:
Igor will positively be the Atlantic's first category five Hurricane in three years...
I agree. I wouldn't be surprised if he is actually a category 5 right now.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
2155. BDAwx
and we're going with the MJO not in our basin right? :O
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2153. Max1023
I think the NHC is waiting until 11 hoping that Igor will weaken a bit so they don't have to call it a 5. (I'm Not really serious)
Member Since: July 22, 2008 Posts: 1 Comments: 286
Quoting all4hurricanes:

Not currently but before 11 maybe even 8, NHC won't admit he's a five until reanalysis and he meets most if not all requirements for being annular, 92L I think will be a TD at 11. There, I think I nailed every pole


No, category 5 does not mean annular. Wilma for example, lowest pressure in the Atlantic Basin...
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Quoting doorman79:


All the way to west meterie and clearview?


Here is West Pasco Florida you can get fresh Crispy Cremes at Walgreens.. go figure..
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2150. hydrus
FIERCE.
Member Since: September 27, 2007 Posts: 1 Comments: 20487
Igor will positively be the Atlantic's first category five Hurricane in three years...
Member Since: Posts: Comments:
2148. dmaddox
Quoting Jedkins01:



gosh what is it with people in here and annular hurricanes? They are very rare, just because Igor is very intense and well organized does not make in annular. Dang.
i dont get it either..hmm
Member Since: May 5, 2007 Posts: 0 Comments: 445
2147. xcool
Papa John
Member Since: September 26, 2009 Posts: 2 Comments: 15620
Hey Taxi, pick up Igor.... Going WNW???
Hey Taxi, taxi.....

Member Since: August 2, 2010 Posts: 21 Comments: 9690

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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.