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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woah, either levi or StormW, after going NW for a while is Pre-julia expected to make a sharp turn to the west?

also, if not, why do during the life of the systems recently a lot of the models runs show this for a couple runs but back off of it and it never happens.

also, what are the chances of a high building in and having igor hit florida?
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Quoting BDAwx:
Apparently all our buildings have to be able to withstand sustained winds of at least 110mph - correct me if I am wrong. I mean it makes sense when everything here is so expensive and we get vicious storms so frequently.
I was just reading up on bermuda.... this blog about Bermuda vs. Florida Is funny....http://www.limeyinbermuda.com/latest_news/2006/06/hurricaneproof_.html some of the comments are spot on tho.
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Quoting hurricanehunter27:
You guys all know it is a Cat 5 right now. The only reason the NHC would not put it at Cat 5 is if it goes through EWR. I bet the winds on Igor are at 160-170mph it is a beast of a storm. The IR sat shows a perfect eye and a nice ring of convection. To me this is the strongest storm iv seen other than rita and wilma.


The only reason it isn't a Category 5 is because we don't have any reliable data other than ADT, which says its at 150 mph. If there was and it was saying it is a Category 5, it would be one. Simple.

Plus, storms this compact and intense rarely go through EWRC's.
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So my best guess for 11pm is:td13,35mph,ts julia,40mph,igor cat4,150mph,first cat 5 by tomorrow morning 160mph....time to get hyper,oh 94l's on the way as well,hmmm could some form along the stationary front that will be dropping south?????,stay tuned.......
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2642. Levi32
Quoting Chicklit:
Quoting Levi32:
Igor will likely be the single greatest ACE contributer to the 2010 Atlantic hurricane season.


We're only half-way there.


Yeah but we probably won't get another opportunity for a storm to develop right off of Africa, literally right off, and then become a major rather fast and take a long track all the way across the Atlantic and make a sweeping recurve. That racks up the most ACE points you can ask for in the Atlantic, and Cape Verde season will be winding down soon.
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Definately starting to worry about Igor because the models are now starting to depict that WNW-NW turn and then back to a W heading right around 65W that I was thinking would happen yesterday. That puts the east coast at threat as I do think all the models will continue to trend west in general.

Member Since: February 12, 2007 Posts: 0 Comments: 479
Quoting Stormchaser2007:
00:15

Perfect eye.

Might be stronger than 150 mph...


Igor is living up to his name...
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2639. Drakoen
Quoting Levi32:
Igor has begun a WSW jog during the last couple hours after being on a due west heading. Just a jog but worth pointing out as it may take Igor south of the next forecast point.


If you look at the water vapor imagery out ahead of the storm you can see that the mid to upper level flow is coming down from northeast which may be why it is taking that jog south of due west.
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Quoting Levi32:



First trough won't do much to him. I think he will be south of the NHC/model forecast at Days 4 and 5. I still think recurvature east of the US is most likely but there is enough variance in the pattern for me to be worried that he tries to come back all the way to the SE US coast. It's still the outlier solution at this point, but it can't be dismissed.


Levi, I'm listening to Storm and he has the same concerns. He's favoring the south tracks at this point and is concerned about that second high without a trof to pull Igor north.
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Link check out the last frame...The eye is smooth all the way around wich means those winds are SCREAMING.
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2636. xcool


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2635. 7544
wow igor double in size in less than 24 hours getting stonger too but still like to go west all eyes on igor

africa wave beats 92l and is julia

92l trying to hold

new blob by the bahamas ?

whats next
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Quoting Levi32:



First trough won't do much to him. I think he will be south of the NHC/model forecast at Days 4 and 5. I still think recurvature east of the US is most likely but there is enough variance in the pattern for me to be worried that he tries to come back all the way to the SE US coast. It's still the outlier solution at this point, but it can't be dismissed.


Trough was weakening when it went through my house in New York today..hardly even rained..
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Quoting Chicklit:
Quoting Levi32:
Igor will likely be the single greatest ACE contributer to the 2010 Atlantic hurricane season.


We're only half-way there.


Agreed!
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Link

I think yhis is one of the latest satellite photo. Can anyone tell me where is the center?
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Quoting AWeatherLover:
The wave behind TD12 looks pretty vigorous this evening. It's looked pretty impressive all day. Reminds me of TS Christina (1972 I believe, but I could be off). It was designated a TD while still over Africa. The only one to do so if I remember correctly.


Ah! Thanks for pointing this out - been looking for a storm that started over Africa all day. Here's Christine:

http://www.wunderground.com/data/dhc_archive_charts/at_1973_charts/at197304.gif
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Quoting CybrTeddy:
Tropical Storm JULIA.

AL, 12, 2010091300, , BEST, 0, 133N, 229W, 35, 1005, TS

10-4-3.

7 more to my prediction. Very probable.



And we are just slightly a little more then halfway through the season...plenty of time for 7-12 more storms.
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2628. Levi32
Quoting luigi18:

Hello Levi i see the jog to the South too ,we are in PR and i begin feeling nervous do you think we are not save yet?


I think it's pretty unlikely that you'd get a direct hit, but there's a chance he passes by close enough to the north that you get the outskirts of the system. Be ready for that possibility, but we'll know more when he's approaching 60W.
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Quoting Levi32:
Igor will likely be the single greatest ACE contributer to the 2010 Atlantic hurricane season.


We're only half-way there.
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You guys all know it is a Cat 5 right now. The only reason the NHC would not put it at Cat 5 is if it goes through EWR. I bet the winds on Igor are at 160-170mph it is a beast of a storm. The IR sat shows a perfect eye and a nice ring of convection. To me this is the strongest storm iv seen other than rita and wilma.
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Quoting cyclonekid:
So..I get Igor and the new Julia I suppose..but will 92L ever develop?? If so, where's the best chance for it to?


If it's going to do so, it needs to do so before it runs into the Yucatan. I'm starting to have my doubts, but I still think it has a decent chance.
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2624. xcool




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SAB has Igor at 6.5.
Member Since: July 8, 2005 Posts: 259 Comments: 24039
2622. bird72
Hurricane Hugo Luquillo Puerto Rico.

Link
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Does anyone have the link for the program that runs annular scans on tropical cyclones? I think MH09 posted it when Earl was up to bat.
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Quoting Stormchaser2007:
00:15

Perfect eye.

Might be stronger than 150 mph...

I agree. I think he's somewhere between 150-160mph.
Member Since: September 2, 2009 Posts: 130 Comments: 21193
2617. Levi32
Quoting kingzfan104:
someone said earlier that you thought this trough had a chance to miss it and the high to build back in and send this toward florida and the SE coast.

1) is this true
2) what chance do you have of this happening



First trough won't do much to him. I think he will be south of the NHC/model forecast at Days 4 and 5. I still think recurvature east of the US is most likely but there is enough variance in the pattern for me to be worried that he tries to come back all the way to the SE US coast. It's still the outlier solution at this point, but it can't be dismissed.
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So..I get Igor and the new Julia I suppose..but will 92L ever develop?? If so, where's the best chance for it to?
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Quoting dmaddox:
officially? by whom?
By the powers vested in this blog.
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Quoting Drakoen:
Water vapor imagery show the eye has completely clear out with the system firing the most intense cloud tops in the southeast quadrant.


Weak wind shear from the south or southeast...a cold east wind at the 200 mbar level...SSTs no greater than 28.5C. Rut roh!
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I didn't know EARTH had a GREAT RED SPOT on it! I'll bet JUPITER is envious tonight!
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00:15

Perfect eye.

Might be stronger than 150 mph...

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2610. BDAwx
Apparently all our buildings have to be able to withstand sustained winds of at least 110mph - correct me if I am wrong. I mean it makes sense when everything here is so expensive and we get vicious storms so frequently.
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Quoting belizeit:
They'll probly make another pass then we will know for sure but i think it has
Thanks.
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2608. luigi18
Quoting Levi32:
Igor will likely be the single greatest ACE contributer to the 2010 Atlantic hurricane season.

Hello Levi i see the jog to the South too ,we are in PR and i begin feeling nervous do you think we are not save yet?
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Quoting traumaboyy:


Great blog post KORI, I take a little nap and you let the place go crazy with a CAT 5???


Thanks man! Igor's certainly a beast. I admit, he even surprised me. Which is rare.
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Yeah, post 2589, it could recurve right into it(Bermuda) It's very possible.
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Quoting Stormchaser2007:
Couple of hours old, but...

WOW



Wow....IGOR IS MONSTER!!!
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Quoting FLGatorCaneNut:


That's exactly what Max Mayfield (retired NHC Director) has preached for many years.... People think there is a cat.2 storm on the way and don't think much of it only to find when they wake up in the morning it's a cat 4 and too late to evacuate etc.


Kinda like what Opal did in 1995..
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2603. jdj32
Recon Data for Google Earth is available at:

http://tropicalatlantic.com/recon/
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Quoting Stormchaser2007:
Couple of hours old, but...

WOW


That image looks so cool!
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Wow that eye is really starting to tighten up
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Quoting KoritheMan:


Doesn't it always?


Great blog post KORI, I take a little nap and you let the place go crazy with a CAT 5???
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Quoting SouthDadeFish:
Imagine if we had a landfalling storm that did that in the 24 hours before landfall. How can you forecast something of that magnitude to happen? The impact would be catastrophic.


That's exactly what Max Mayfield (retired NHC Director) has preached for many years.... People think there is a cat.2 storm on the way and don't think much of it only to find when they wake up in the morning it's a cat 4 and too late to evacuate etc.
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48 hr out

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Quoting AWeatherLover:

Ah, thanks for that. I didn't know that. Do you have a link or anything so I can see some of them? TIA


Link

It's just the HURDAT for the depressions from 1967-1987, I can't find the maps, but if you look at the data, if it's east of 20W, it'll be over africa.
Member Since: October 15, 2008 Posts: 11 Comments: 2312
Quoting Levi32:
Igor has begun a WSW jog during the last couple hours after being on a due west heading. Just a jog but worth pointing out as it may take Igor south of the next forecast point.
someone said earlier that you thought this trough had a chance to miss it and the high to build back in and send this toward florida and the SE coast.

1) is this true
2) what chance do you have of this happening
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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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