Potentially dangerous 92L steadily developing; Igor nears hurricane strength

By: Dr. Jeff Masters , 3:04 PM GMT on September 11, 2010

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A tropical disturbance (92L) over the Eastern Caribbean, a few hundred miles south of Puerto Rico, is steadily organizing and appears likely to develop into a tropical depression by tonight or Sunday morning. Satellite loops show an impressive and expanding region of heavy thunderstorms, with good spiral banding and respectable upper-level outflow on all sides. Long range radar out of Puerto Rico shows that heavy rains are now affecting that island, but there is no rotation to the radar echoes evident. However, the rain bands are becoming more intense and more organized. San Juan, Puerto Rico reported a heavy rain squall at 8:44 am this morning, and radar estimates suggest two inches of rain fell in this squall just southeast of San Juan. Wind shear over 92L is low, 5 - 10 knots. The waters beneath are at near-record warmth, 30°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-northwest at 11 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 Mexico's Yucatan Peninsula on Wednesday. The HWRF model has a more northwesterly track, taking 92L over the Dominican Republic, Haiti, and Cuba, but this model has been trending too far north in its tracks. I expect 92L will follow a path south of the islands, bringing it near or just south of Jamaica on Monday, then into the Yucatan Peninsula on Wednesday. On this track, the southern Dominican Republic can expect heavy rains of 3 - 6 inches tonight through Monday morning; southern Haiti can expect similar rains Sunday through Monday, and Jamaica and the Cayman Islands can expect heavier rains of 4 - 8 inches Monday and Tuesday. Eastern Cuba will probably escape 92L's heaviest rains in this scenario (Figure 2.)

Intensity forecast for 92L
I can't find any reason to doubt this will be a tropical storm by Sunday or Monday, and potentially a Category 1 or 2 hurricane by Wednesday, if 92L avoids passage over Hispaniola and Cuba. The SHIPS model predicts wind shear will remain low, 5 - 10 knots, through the period, and makes 92L a Category 1 hurricane by Monday night. 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. The first Air Force Hurricane Hunter mission into 92L is scheduled for Sunday afternoon, but there will be a research mission by the National Center for Atmospheric Research G-V jet today that will give us valuable information on 92L's large scale environment and potential for development.


Figure 2. Forecast rain amounts from 92L from the 2am EDT Saturday run of the GFDL model. This model predicts most of 92L's heaviest rains will miss Haiti, but will affect Jamaica, the Cayman Islands, and the Yucatan Peninsula. Image credit: Morris Bender, NOAA/GFDL.

Igor
Tropical Storm Igor is very close to hurricane strength, and appears destined to become a large and powerful major hurricane over the Central Atlantic in the days to come. Wind shear is moderate, 15 - 20 knots, waters are warm, 28°C, and Igor has moistened its environment enough to keep the dry air of the Saharan Air Layer (SAL) at bay. Igor will track west under the influence of a strong ridge of high pressure for the next three days, then turn more to the west-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 has a slight chance of making landfall on the U.S. East Coast or Canada. Climatology shows that about 10% 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 5% for Canada. The forecast steering pattern for the coming two weeks from the GFS model 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. The odds of Igor hitting land in the U.S. or Canada are probably close to their climatological 10% and 5% probabilities, respectively.

Elsewhere in the tropics
A new tropical wave (Invest 93L) emerged from the coast of Africa yesterday, and is already showing signs of organization. Most of the models predict 93L will develop into a tropical depression 2 - 4 days from now, and NHC is giving 93L a 30% chance of developing by Monday.

Next post
This may be my only post today; I'll have a new post Sunday morning.

Jeff Masters

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1723. angiest
Quoting weatherxtreme:
Igor...here FISHY...FISHY


GFS has him over Bermuda for a couple of days on the 0Z run...
Member Since: August 26, 2006 Posts: 16 Comments: 4766
Quoting KoritheMan:


Aw, don't be down on yourself. :/


Thanks Bro!!....It doesn't bother me....next to you smart ones..I am an Idiot.....
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Igor...here FISHY...FISHY
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1719. xcool
hmmm taco bell Think Outside The Bun soo good anyway
Member Since: September 26, 2009 Posts: 2 Comments: 15603
1717. xcool
btwntx08 yeah
Member Since: September 26, 2009 Posts: 2 Comments: 15603
Quoting thewindman:
What happened to the "experts" saying La Nina will steer storms towards the US

Guess what guys NOT ONE LANDFALL IN THE U.S.

I guess that makes me a troll for being right


what happened is we all along the coastline have dodged a few bullets this year.....just curious, since you live in maine, have you ever been through a hurricane?
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Quoting Grecojdw:
Wow it looks like this pattern set up is favoring storm sin the Caribbean to hit N.Mexico into Southern Texas. There shouldn't be a concrete pattern change that takes effect to threaten the Central and Eastern Gulf until the fronts start diving further South by the end of September towards fall....good luck Texas:0


Lol. You still pickin' on Texas?
Member Since: August 24, 2010 Posts: 0 Comments: 459

Comrade Igor.
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Well hopefully here in NE florida we won't have to worry about monster Igor and maybe out with the FISH!
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Quoting gordydunnot:
Tampa spin don't put unnecessary pressure on everyone above average would be quite impressive on this blog.IMo, most of us must just dwindle on and hope for the occasional salutation.


Huh...i don't understand what you are saying...LOL.....sorry.
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1709. angiest
At 228 hours, GFS is developing a Caribbean system again:

Member Since: August 26, 2006 Posts: 16 Comments: 4766
What happened to the "experts" saying La Nina will steer storms towards the US

Guess what guys NOT ONE LANDFALL IN THE U.S.

I guess that makes me a troll for being right
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92L

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Quoting thewindman:
Get your skis out. Snow is almost upon us in the Northeast. Hurricanes??? sorry that season is almost over. It is Recurve time. The east coast troughs are in charge now. Looking for some fall colors soon up here in Maine


must be nice......still 97 degrees in south lousiana.....gulf is still boiling. season isn't over for us yet.
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1705. beell
night, cowboy.

all that analysis stuff regarding Igor is questionable that far out-but that's the guess tonight. Remember Earl, lol? As you mentioned earlier, 92L will probably gain some beta-latitude before getting under the ridge.

I'm out also.

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WoW! Igor is already huge! Will he eventually go out with the FISHES?
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I hate to type this but maybe 92L is giving Haiti a break.Thank the lord because it sure looked bound and determined earlier today.
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1702. JLPR2
Quoting traumaboyy:


Looks like it completely dissipated then new flair up of convection........this season making me feel like a complete idiot (more than I usually feel I mean)


But it's firing around.
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Get your skis out. Snow is almost upon us in the Northeast. Hurricanes??? sorry that season is almost over. It is Recurve time. The east coast troughs are in charge now. Looking for some fall colors soon up here in Maine
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Quoting xcool:
TampaSpin How much do you LOVE YOU ngp 10% or 50% ?? hmm


Its my favorite model as it is usually slow at show things but, when it does watch out as it is slower at showing things than other models i have always believed. Like i said it is my favorite model and when it shows the same as others i will always favor it when it has other models showing the same. Just my opinion.
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Quoting traumaboyy:


Looks like it completely dissipated then new flair up of convection........this season making me feel like a complete idiot (more than I usually feel I mean)


Aw, don't be down on yourself. :/
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Quoting thewindman:
Sept/Oct/Nov = Recurve season

winter is upon us we might as well wait for next season.
Troll-much?
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Quoting xcool:
poor 92L


Looks like it completely dissipated then new flair up of convection........this season making me feel like a complete idiot (more than I usually feel I mean)
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Quoting atmoaggie:
Well, Kori-the-troll, anything else to say for yerself? (j/k, of course)


:(
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So it seems we will have a nice Swell - Good surfing at Pine Grove, Isla Verde.... or maybe La Ocho....
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Tampa spin don't put unnecessary pressure on everyone above average would be quite impressive on this blog.IMo, most of us must just dwindle on and hope for the occasional salutation.
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Thanks for your response Relix
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Wow it looks like this pattern set up is favoring storm sin the Caribbean to hit N.Mexico into Southern Texas. There shouldn't be a concrete pattern change that takes effect to threaten the Central and Eastern Gulf until the fronts start diving further South by the end of September towards fall....good luck Texas:0
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1691. xcool
oct noo Recurve oh yeah nov noo Recurve
Member Since: September 26, 2009 Posts: 2 Comments: 15603
Sept/Oct/Nov = Recurve season

winter is upon us we might as well wait for next season.
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1689. Relix
Quoting sunlinepr:
What is going to make Igor turn NW? There's dry air in front of him and the trough is far behind, and way up to the North? He can keep on going west for a while.....



I know you are worried about Igor. It's NOT coming here, don't worry. It will get picked at some point after 48W and towards 60W. That's an awful space to go up. It's already up to 17.7. We won't even feel rains from this one XD!
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1688. xcool
TampaSpin How much do you LOVE YOU ngp 10% or 50% ?? hmm
Member Since: September 26, 2009 Posts: 2 Comments: 15603
Quoting KoritheMan:


No... That's not it...
Well, Kori-the-troll, anything else to say for yerself? (j/k, of course)
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Quoting NEFLWATCHING:
yeah, it will indeed. maybe that day I can borrow that avatar wth bugs bunny sawing off the state of florida and letting it drift away.
Further, depending on the angle of approach, the shallower shelf waters there, relative to S FL, and the concave shape of the shoreline will make a surge especially bad. For any decent-size and powerful storm coming in close to perpendicular to the shore, that is.
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1684. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15603
Quoting F4PHANTOM:
Looks like another trough over the Miss. valley that may have an effect. My question is ; What happened to 93 & 92? hard to believe NOGAPS would drop an invest.


A lot of peeps don't like the NOGAPS as it is a very conservative model but, i love it because it keeps one pretty honest.
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1682. angiest
0Z GFS wants Igor to take a day or two to clear Bermuda..
Member Since: August 26, 2006 Posts: 16 Comments: 4766
1681. JLPR2
Quoting traumaboyy:


LOL....Good evening.....I wanted to say that one night last week looked at some of your photos and they are AMAZING!! +++


Thank you, I try my best. :D
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1680. xcool
traumaboyy .:)))
Member Since: September 26, 2009 Posts: 2 Comments: 15603
Quoting JLPR2:
whooops, ignore my whoops LOL!


LOL....Good evening.....I wanted to say that one night last week looked at some of your photos and they are AMAZING!! +++
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Wow 92L.
http://www.ssd.noaa.gov/goes/flt/t2/ir4-l.jpg
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Seen those models, Tampa. Thanks for your input
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Quoting KerryInNOLA:
The trollcasters are just trying to gain respect from the "professors" on this blog. Don't let them bother you.


No... That's not it...
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1673. xcool
poor 92L
Member Since: September 26, 2009 Posts: 2 Comments: 15603

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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.