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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1673. xcool
poor 92L
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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.....

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1671. wjdow
Quoting TropicalAnalystwx13:


He wasn't Personal attacking you, he was asking a simple yes/no question.


personal q which was none of his business really, don't you agree?
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1669. angiest
162 hours. Looks like he has been sitting on Bermuda for a long time.

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1668. JLPR2
whooops, ignore my whoops LOL!
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Not sure Igor hits the weakness in the GFS either the way it looks before the High moves over head. This is gonna be all about timing now. If Igor speeds up that would be a good thing. If he slows down we might really be in trouble.
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1666. beell
Quoting atmoaggie:

Hmmm.

Happy WU-niversary, Beell. (Yer join date?)


Hey, atmo.
Thanks. Actually joined in 2006-started over with the current handle on 9/11/07.

By far, the lesser of the two evils for this day in our history.
(

Good to see you dropping in again.
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1665. angiest
And at 150 hours

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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.
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expect convection to start building up in 92L between 12 and after sunrise
Member Since: June 13, 2009 Posts: 2 Comments: 12157
Quoting KerryInNOLA:
I think the main concerns for the US for the rest of this year are storms like Hermine, W Carib storms and storms popping up in the Bahamas. The CVs just ain't going to make it. There is not going to be any pattern change except one called Fall.


It will be very interesting to see if what stormW has been talking about pans out next weekend - early next week.
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1660. angiest
0Z GFS +132 hours. Hmmm

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Quoting foggymyst:
Tampa- thoughts?


I don't like the look of Igor at all.....i don't think its gonna hit that Trough. Its coming WEst i belive now. Hopefully another Trough gets there in time to make it turn North...Honestly anywhere from South Florida to the Carolinas need to watch this potential monster. Just my opinon as ussual!
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Quoting beell:


Probably not much effect on 92L-aside from a a southward diving split over the middle atlantic states in the jet that may reinforce the GOM/Carbbean ridge to the N of 92L.

For Igor, strong westerlies in place for a while-displaced more to the south than we have seen. Erosion of the middle atlantic ridge and a path up and out.

Would be nice if we could drag Bermuda out of the way for a while.



Again, good stuff. I've enjoyed your atmospheric analyses. Sounds good for the CONUS, may be trouble for the Yucatan. And, agreed on Bermuda - got a target on it!

I'm done, y'all. Have a good sleep!

MLC <---------------------out for some shuteye!
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Quoting NEFLWATCHING:




You can drag it down to the northeast coast of florida - LONG time since we've had a direct hit. :)
Your "someday" will come...
...eventually.
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sorry - i was referring to dragging bermuda out of the way for the fish storms - quote did not work.
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You can drag it down to the northeast coast of florida - LONG time since we've had a direct hit. :)
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1653. beell
Night, Levi.
)
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Quoting KimberlyB:


"DING!" That's the sound of the shine off my halo! lol

I'm hanging in there bud. I've been hurting bad, so I've just been popping on and off and reading a bit while I can.

How's by you? What's your thoughts on our storms?


Not much in My thinking from Yesterday update .....did you read on my Website. Also for you all i put up models like the one i posted on my blog if you all wanta view. I obviously have the same on my website as well.
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Tampa- thoughts?
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Quoting beell:


Probably not much effect on 92L-aside from a a southward diving split over the middle atlantic states in the jet that may reinforce the GOM/Carbbean ridge to the N of 92L.

For Igor, strong westerlies in place for a while-displaced more to the south than we have seen. Erosion of the middle atlantic ridge and a path up and out.

Would be nice if we could drag Bermuda out of the way for a while.


Hmmm.

Happy WU-niversary, Beell. (Yer join date?)
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From the latest discussion:

A 1009 mb surface low is in the ern Caribbean centered near 15n66w moving W near 15 kt (better than 17 mph).
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1647. beell
Quoting moonlightcowboy:
Beell, what's your take on the diving jet stream's effect on 92L's future steering, or Igor for that matter? TIA


Probably not much effect on 92L-aside from a a southward diving split over the middle atlantic states in the jet that may reinforce the GOM/Carbbean ridge to the N of 92L.

For Igor, strong westerlies in place for a while-displaced more to the south than we have seen. Erosion of the middle atlantic ridge and a path up and out.

Would be nice if we could drag Bermuda out of the way for a while.

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Quoting KoritheMan:




Thats to the point, and very cool!
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Quoting KoritheMan:


LOL

I knew you'd be appalled at that. Sorry bro. ;)

I'm not necessarily insinuating anything for your area specifically. Just trying to alert people that the threat for a US landfall somewhere, isn't over.


My nightmares are going to get worse.....KORI..THE MAN TRYING TO BLOW ROOF OFF MY HOUSE.....lol.....
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This looks really bad! Big change for the NGP Model......geesh!
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Quoting traumaboyy:


Kori....for the love of pete.....can't we just forget about that particular year??


LOL

I knew you'd be appalled at that. Sorry bro. ;)

I'm not necessarily insinuating anything for your area specifically. Just trying to alert people that the threat for a US landfall somewhere, isn't over.
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1641. xcool
TropicalAnalystwx13 anyway moved onn thanks
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Quoting TampaSpin:


Your always a trouble maker on here...:)...NEVER are you..How you doing!


"DING!" That's the sound of the shine off my halo! lol

I'm hanging in there bud. I've been hurting bad, so I've just been popping on and off and reading a bit while I can.

How's by you? What's your thoughts on our storms?
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Quoting KoritheMan:


No, he's calling ME a troll. That's the hilarious thing. But, I'm mature enough to handle it without backlash. Now we'll see if he's mature. :)


KORI....NOT TROLL!!
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92L activated during the day, disapeared in the night....
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Quoting Levi32:


Upper clouds are moving faster than the low-level ones, and we have had no idea exactly where the surface center has been all day, so we can't assume it's moving along with the mid-level center which hasn't been vertically stacked with it. The upper clouds are causing the illusion that the system has sped up significantly, but that likely isn't the case.

~~~~~~~~~~~~~~~~~~~~

I'm out, goodnight all.



Uuum, "right to left" or "east to west" is pretty easily seen, Levi. LOL. And, it's moving at a very quick clip! No doubts about it!

Good night.
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Quoting KoritheMan:
A season with a very similar synoptic scale pattern as 2010:



Notice that the vast majority of the observed storms recurved. However, Caroline and Eloise were both majors, and both struck a portion of the Gulf Coast. The latter was the first major hurricane to strike the Florida panhandle in many years at the time.


Kori....for the love of pete.....can't we just forget about that particular year??
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Quoting earthlydragonfly:
taken tonight

it will be on local channel 2 in orlando on Monday


Your photos are always just gorgeous!
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Quoting btwntx08:

the person he quoted isnt a troll


No, he's calling ME a troll. That's the hilarious thing. But, I'm mature enough to handle it without backlash. Now we'll see if he's mature. :)
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Quoting earthlydragonfly:
taken tonight



it will be on local channel 2 in orlando on Monday


congratulations that is phenomenal.
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1630. Levi32
Quoting moonlightcowboy:



Yep, Beell, we're on the same page. The weakness is closing, not as pronounced. And, it only takes eyeballs to see 92L react quickly to the low-level flow, shooting it westwards.

It's alright, Levi, you do really good. But, all of these dynamics can sometimes fool the best of us, least of which is me.


Upper clouds are moving faster than the low-level ones, and we have had no idea exactly where the surface center has been all day, so we can't assume it's been moving along with the mid-level center which hasn't been vertically stacked with it. The upper clouds are causing the illusion that the system has sped up significantly, but that likely isn't the case.

~~~~~~~~~~~~~~~~~~~~

I'm out, goodnight all.
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Quoting KimberlyB:


Hey Tim! I know that I probably am. I doubt if anyone has ever clicked a + or - for me. lol


Your always a trouble maker on here...:)...NEVER are you..How you doing!
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Quoting TampaSpin:
My dang WU setting for some reason is set for show average and i can't see much of anyones post. Are you all below average......LOL


We are all below average...lol
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A season with a very similar synoptic scale pattern as 2010:



Notice that the vast majority of the observed storms recurved. However, Caroline and Eloise were both majors, and both struck a portion of the Gulf Coast. The latter was the first major hurricane to strike the Florida panhandle in many years at the time.
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Quoting xcool:
Krycek1984 okay anyway did i asking you personal attacks me noo thank bye.


He wasn't Personal attacking you, he was asking a simple yes/no question.
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Quoting dracko19:
Hey, do you remember that movie "The Perfect Storm"? It was about a fishing ship that was lost at sea off the NE USA coast in a "storm of the century", which turned out to be a Cat 4 Hurricane merging with a low pressure system creating a ..."Super Subtropical Storm".

Take a look at this:
Link

This is the GFS Long Range Model. Take a look how it handles IGOR in the long term (8+ days out) It blows it up to a cat 5 and then takes it right over Bermuda!! (That would destroy Bermuda) Then, it merges with a low over New Foundland and creates a Super-SubTropical storm on Sep 23rd. Very interesting...


18z GFS.

108 knots.

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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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