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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ok so at 11 Igor should be cat 2 atleast and TD 12 35mph and at 1pm TWO 92L should be back up to red and at 5 Igor sould be a cat 3 TD 12 should be or near TS and TD 13 forms
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Quoting WeatherNerdPR:

Igor = T6 IMO.


I concur.
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Quoting help4u:
I have seen no official forcast taking this storm to Bermuda.Just the opposite of what you said would take a big change for it to hit Bermuda.


No, the official forecast is not out that far yet, but reliable models are taking it dangerously close to or over Bermuda.
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Quoting Stormchaser2007:
Here are the ADT examples.


And here is Igor


Igor = T6 IMO.
Member Since: July 7, 2010 Posts: 0 Comments: 5682
Quoting barotropic:


Loks more like its gonna pass near or right over bermuda


Keep in mind the "west" bias adjustment with the models as the hurricane gets closer.
Happened with Danielle... Earl.. etc.
Models Schmodels

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Quoting WeatherNerdPR:

I almost had a stroke when I saw that.

That's what Igor does.
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Quoting Stormchaser2007:
00z NCAR WRF made Igor huge.

Ummm, wow. Seems off...
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2465. surfmom
Hurristat -- YOU'RE BACK mi Amigo!!!!!! Lots on the plate to look at this morning!!! Wonder if you'll get enough good snow to make an igloo this winter --I will never forget that snow castle igloo you built 2 years ago!!
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2464. help4u
I have seen no official forcast taking this storm to Bermuda.Just the opposite of what you said would take a big change for it to hit Bermuda.
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Here are the ADT examples.


And here is Igor

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Quoting surfmom:
LOL - ahhh noo
We're LAKE DE MEXICO this morning, water 89 degrees


I need to come visit you this week instead of going to jury duty. Beautiful!
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I sure hope Bermuda does not become complacent as the last three storms that were heading our way, fizzled out.
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Quoting RecordSeason:
2422:

I'm telling yah, the NHC is low-balling the intensity right now.

they are hoping it will die down some before it starts to get close to land, so they never have to tell anyone how strong it is.

This even happened with Earl, as they had 177kts sustained flight level winds, which should have translated to cat5 even at the surface. They just figured not tell anyone and hope it don't hit....


LOL you are kidding about this statement, right?

"hey are hoping it will die down some before it starts to get close to land, so they never have to tell anyone how strong it is".
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Quoting surfmom:
LOL - ahhh noo
We're LAKE DE MEXICO this morning, water 89 degrees


Wow, that's pretty nice :D
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Morning: 92 L looks good. Should be a TD by tonight.
Evening: 92 L just lost all convection and is dying in the face of dry air. RIP.

Wash, rinse, repeat.

(really, this is like getting excited by the diurnal cycle of surface pressure at a buoy.)

So what's it going to do? I'm with the NHC, giving it a 50%.
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2457. surfmom
Quoting aquak9:


that makes three of us

surfmom- it's flat here on the est coast, maybe better where you are
LOL - ahhh noo
We're LAKE DE MEXICO this morning, water 89 degrees
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Quoting Stormchaser2007:
00z NCAR WRF made Igor huge.



How about 92L in the Western Carribean? That looks mighty big...
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Quoting Stormchaser2007:
00z NCAR WRF made Igor huge.


I almost had a stroke when I saw that.
Member Since: July 7, 2010 Posts: 0 Comments: 5682
2454. mbjjm
New tropical discussion posted at Crown Tropical Weather
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TD12 is looking good for a system so far east.

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00z NCAR WRF made Igor huge.

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Quoting Stormchaser2007:
Wow


Wow! That's really impressive.
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Quoting RecordSeason:
2404:

Well, recurve east of Bermuda would take a MIRACLE at this point.


Loks more like its gonna pass near or right over bermuda
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Quoting Chicklit:
good morning, 92L fired up this morning.


....should be a td by tonight imo,caymans should be keeping a eye on this likely to effect them in some fashion,what's up surfmom!!!!(i see u all the time jogging,i have the gold sunfire)
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Tropical Depression 12
13.3 N 20.1 W
Heading west at about 17mph
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Quoting Stormchaser2007:
Wonder what the NHC will do with their intensity estimate because right now its about 30 knots too low.

CI# /Pressure/ Vmax
5.9 / 952.4mb/112.4kt


Heh.
Member Since: July 7, 2010 Posts: 0 Comments: 5682
2445. breald
Quoting Sfloridacat5:


Bermuda is constantly under the gun from Atlantic forming Tropical Systems. Lucky for Bermuda, its a small target in a big ocean. How many storms have threatened Bermuda just this year?


Who cares how many close calls they have had? I am talking about this storm. It takes one storm to have a huge impact. This storm could be the one. As far as I can see, they are they only land mass that is currently under the gun for a possible impact.
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Wonder what the NHC will do with their intensity estimate because right now its about 30 knots too low.

CI# /Pressure/ Vmax
5.9 / 952.4mb/112.4kt

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Quoting Stormchaser2007:
Uploading a bunch of new images of Igor.

Check them out.



Nice pics.
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Quoting Stormchaser2007:
Uploading a bunch of new images of Igor.

Check them out.



Cool!
Member Since: July 7, 2010 Posts: 0 Comments: 5682
2441. aquak9
Quoting breald:


LOL. I am sitting right next to you in the back of the class when it comes to weather.


that makes three of us

surfmom- it's flat here on the est coast, maybe better where you are
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Quoting Stormchaser2007:


Sure

Thanks a million!!
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Quoting PRweathercenter:
That's a beautiful shot of Igor, could send me that link????
:-)


Sure
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Quoting surfmom:
......lucky dog....I'm wave craving....the roadtrip to the FL east coast is looking necessary -I'm not complaining - just would be nice to get a rainw/no name event for a wee bit of action here...


Hey surfmom! I'm back :D
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Quoting TheDawnAwakening:


He needs to go far to the west to spare Bermuda any impacts, the eastern side of the storm is the most dangerous and strongest side of the storm, as well as potentially the widest where tropical storm force winds extend to great distances. You want the hurricane to recurve east of Bermuda. Threat for a Bermuda impact is increasing.

Igor need to follow a similar track to Earl.
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Quoting breald:


LOL. I am sitting right next to you in the back of the class when it comes to weather.


We have a nice row back here together. *S*
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Quoting RecordSeason:
2417:

The CDO is small, but his inflow is actually quite large. We may see him expand in size over time.

I know, but he's small convection-wise for a hurricane named Igor. For now.
Member Since: July 7, 2010 Posts: 0 Comments: 5682
Quoting Stormchaser2007:
I think Igor should become a major hurricane later today.

That's a beautiful shot of Igor, could send me that link????
:-)
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Igor looks good. With that said,.......



Fly Eagles Fly
On the road to victory
Fight Eagles Fight
Score a touchdown 1 2 3
Hit em low
Hit em high
And watch our Eagles fly
Fly Eagles Fly
On the road to victory

E A G L E S

EAGLES!
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2431. breald
Quoting surfmom:
LOL - mayabe I need espresso this AM - just got confused (which is easy - i belong in the back of the class)


LOL. I am sitting right next to you in the back of the class when it comes to weather.
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2430. Ryuujin
RI anyone? This will most assuredly change things in terms of path, overall strenghth and how he'll affect the ridge to his NE and if the trof does or doesn't get cut-off... Amazing
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Igor predicts ...

19

see: 2422 by Stormchaser2007
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Final CI# is 5.9

I think this could very well be a major hurricane sometime today.

T# Chart.



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Sorry for the lack of commentary by me. I was unaviodably detained. (Had to take a shower. :P)
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Quoting RecordSeason:
2416:

Unfortunately for bermuda, the maximum potential intensity map shows the water and atmospheric conditions near bermuda can support a greater-than-150kts cat5 hurricane...

Intensity map

Quoting Stormchaser2007:
Wow


O_O
Member Since: July 7, 2010 Posts: 0 Comments: 5682
2424. surfmom
Quoting serialteg:


bermu must track closely. hoping for some surf again in the carib. :D
......lucky dog....I'm wave craving....the roadtrip to the FL east coast is looking necessary -I'm not complaining - just would be nice to get a rainw/no name event for a wee bit of action here...
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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.