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 PrivateIdaho:
...do a round of golf in about 45 minutes I suspect. :^)
Alas, I'm not allowed to take it on the course as of yet. Also, I have to make too many swings at the ball to go that fast. Working on it though.
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Quoting PcolaDan:

Ah, but a square is a rectangle, but a rectangle is not necessarily a square.


Ahh, spoken like a math teacher...
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3543. 7544
hey anyone kmow what time is the new cmc run worth staying up for imo thanks
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So...Any photographers in here tonight? Thinking about taking the plunge on an L-series lens. The 70-200, but I think I read it isn't weather sealed...That would be a real downside for me.
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3541. Torgen
Quoting weathernerdcc:


I can hear Igor's GPS saying "Turn Right, Turn Right".....


No, he hears ME saying "Turn Right, TURN RIGHT!!!"
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Quoting TexasHurricane:


yeah, who knows what it is going to do. Where is that hurricane crystal ball.... :)


I've been wishing for one of those for years. No luck yet. The GFS has picked 92l back up again. Taking it weakly into NE MEX.
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3539. pcola57
12Z CMC Ensembles

Link


Earthquake Data on RSOE EDIS


Link
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looks like some major surf for pr. woot
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Quoting bassis:
Igor seems to be loosing his cold tops on the south side, any guesses why
My layman's guess would be the slight restriction of the outflow to the NW. Although, I'm not well-versed enough to give a detailed, technical explanation. However, the newly minted "Washing Machine Theory", may hold some promise.
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Quoting AtHomeInTX:


Ok. Thanks. Our (Beaumont) channel said about the same earlier. Seeing things like the high moving east by Thursday and the upper ridge weakening was getting knida worrisome. Hopefully 92L won't get too bad.


yeah, who knows what it is going to do. Where is that hurricane crystal ball.... :)
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Quoting F4PHANTOM:
Marshall showed the statistical models and said may or may not become anything. Just keep an eye out for any thing.


Ok. Thanks. Our (Beaumont) channel said about the same earlier. Seeing things like the high moving east by Thursday and the upper ridge weakening was getting knida worrisome. Hopefully 92L won't get too bad.
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Quoting StormJunkie:
Evening all

Igor is a nasty little beast...

And since it still a ways out, here's a little westcasting humor...

OMG!!!! It's missing the turn! Look at the Xtrap model!

IMG alt="" Http


I can hear Igor's GPS saying "Turn Right, Turn Right".....
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Quoting PSLFLCaneVet:
Thanks. Yep, it's a rush to drive around. Thanks for looking at it. Mr. Potato Head suits the current mood of the blog, during the day, much better. LOL
...do a round of golf in about 45 minutes I suspect. :^)
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It's getting really deep in here!
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Quoting texascoastres:
They say going very close to jamaica and over the yucahtan with Twc saying same thing with possible landfall on Brownsville


If that is the case...Brownsville should just keep all there patio table and chairs put up for the rest of the season.....
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3528. 7544
CANT wait to see the new cmc run look how it bends igor westward close to fla will the next run be closer or up up and away anyone know what time the next run will be thanks akk all eyes on igor

Link
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I will say this before I go off to bed expect 92L to rebuild the convection starting 12:00 which is in about less than an hour time the the real trouble starts
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3526. djdanik
Quoting Ryuujin:


That's a really scary thought.

and that's what I meant by REAL monster. He's already terrifying as it is. I couldn't imagine if he got to be a huge, huge hurricane. He's going to be fun to watch, that's for sure.


a ballet dance, closes her arms and goes faster, but occupies small space. same ballet dancer opens arms goes a bit slower but occupies more space. same theory for hurricanes.
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Quoting AtHomeInTX:


I'm not sure. But I'll behave now. Lol. Good evening Trauma. :)


:-)

I know I have been in the medical profession too long but the word "annular" really gets me.....it seems like something we would prescribe a cream for....lol
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They say going very close to jamaica and over the yucahtan with Twc saying same thing with possible landfall on Brownsville
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3523. bassis
Igor seems to be loosing his cold tops on the south side, any guesses why
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JB thinks carib storm will probably affect same area as Alex/Hermine
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3520. xcool


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2010SEP13 014500 6.8 928.6/ +2.0 /134.8 6.7 6.7 6.7 NO LIMIT ON OFF 16.74 -69.10 EYE 23 IR 17.59 47.51 COMBO
2010SEP13 021500 6.8 928.6/ +2.0 /134.8 6.7 6.6 6.6 NO LIMIT ON OFF 15.04 -68.88 EYE 22 IR 17.60 47.61 COMBO
2010SEP13 024500 6.8 928.6/ +2.0 /134.8 6.6 6.5 6.5 NO LIMIT ON OFF 15.84 -67.93 EYE 21 IR 17.55 47.64 COMBO
2010SEP13 031500 6.8 928.6/ +2.0 /134.8 6.5 6.4 6.4 NO LIMIT ON OFF 15.24 -66.88 EYE 21 IR 17.55 47.80 COMBO
2010SEP13 034500 6.8 928.6/ +2.0 /134.8 6.5 6.4 6.4 NO LIMIT ON OFF 15.94 -66.55 EYE 20 IR 17.56 47.90 COMB

another wsw jog, south of 17.6N now
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Link

Updated Blog Tropical Cyclone Igor and Julia forecasts. Good night everyone.
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3516. Ryuujin
Quoting Levi32:


Yup that's what happens when a hurricane still in its immature phase decides to rapidly intensify. If he undergoes an EWRC now, he will come out the other side as a much larger hurricane.


That's a really scary thought.

and that's what I meant by REAL monster. He's already terrifying as it is. I couldn't imagine if he got to be a huge, huge hurricane. He's going to be fun to watch, that's for sure.
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3515. 7544
igor likes going west and still is stay tuned as igor maybe the no 1 talk of this season and living up to his name KRAZY IGOR
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Quoting traumaboyy:


Mornin/Evening Maam.....what have you gotten into now??


I'm not sure. But I'll behave now. Lol. Good evening Trauma. :)
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Sleep well, Igor will behave like most models predict and will move WNW....


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3377. angiest
3462. oracle28

We have a tie tonight for "Poster of the Most Annular Observation" ..
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Quoting TexasHurricane:


let us know what they say...


Yes please. :)
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Quoting PSLFLCaneVet:
LOL, I haven't had any since I changed mine either. Must be because many are so eager to be the first to say something profound, that they pay no attention. They certainly don't have time to make good use of the auto-spellcheck feature or the "preview comment".
39 mph in a golf car!...and it's eco-friendly!
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3508. Levi32
Quoting StormJunkie:
He's a sort of little bugger...Nasty, but a little on the small side no?



Yup that's what happens when a hurricane still in its immature phase decides to rapidly intensify. If he undergoes an EWRC now, he will come out the other side as a much larger hurricane.
Member Since: November 24, 2005 Posts: 628 Comments: 26454
Member Since: May 28, 2010 Posts: 0 Comments: 171
3506. Levi32
Quoting KimberlyB:


Is that a sign of something to come, or something sign of something he's doing now? Is it a sign of weakening / strengthening for example, or is it simply an observation?


In the development stage spiral banding indicates further organization and strengthening, but in this case the development of spiral banding is a downgrade from annular, and Igor is weakening a tad off of what he was a few hours ago. The banding is forming now because his circulation is spreading out and getting bigger, likely due to the slight pressure rise that occurred in the eye.
Member Since: November 24, 2005 Posts: 628 Comments: 26454
Quoting KanKunKid:


I'm struggling with it. The filter is clogged so I took it out to clean it and it was full of shi*. Then I noticed the filter by-pass valve was on. I broke the handle trying to turn it off. So the filter is in place, but if the Sh** is overloading, it goes through the by pass and I can't do nothing about it.
But I'm going to bed soon and that should help.

What's your excuse? hee hee hee..
funny...my wife is always asking me that!
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He's a sort of little bugger...Nasty, but a little on the small side no?

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Quoting AtHomeInTX:


Er yeah thats what I meant SmileyCentral.com


Mornin/Evening Maam.....what have you gotten into now??
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Quoting texascoastres:
Channel 2 in Houston is going to talk about 92l in a few minutes


let us know what they say...
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3500. Levi32
Quoting NOSinger:
Levi...in your tropical tidbit yesterday you talked about a japanese model of some sort...and it had Igor beelining WEST because of a strong ridge...I may not be totally right in my explanation but I know you know what I'm talking about...anyway, do you feel that's what might be setting up right now?


Igor is only very slightly off of the forecasted heading. We can't derive a long-term track change from that. I feel the models are still too far east, but a recurve east of the US still remains the most likely outcome. However, there is something to be said for the JMA model, which makes some meteorological sense, so folks on the eastern seaboard should by no means be writing this off yet.
Member Since: November 24, 2005 Posts: 628 Comments: 26454
3499. xcool
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Channel 2 in Houston is going to talk about 92l in a few minutes
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3496. xcool
buzzz rob
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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.