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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BLOG UPDATE
92L, 93L, Igor 9/11/10
Member Since: Posts: Comments:
Quoting PensacolaDoug:
Re: 52
Not everybody..He's not makin' me mad.


Mad as in "Mad as a Hatter"?
or as in "I'm mad as hell and I'm not taking it no more!"

He isn't making me mad either way. There is no circulation (seen) in 92L YET.
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Quoting KanKunKid:


Yeah, but neither will I.

lol
Member Since: July 7, 2010 Posts: 0 Comments: 5725
Quoting MZT:
I will agree that 92L could achieve "Alex-like" proportions if it continues to organize as it has been doing.

My gut says TD by 5PM advisory.

Everyone's gut has been saying that.
Member Since: July 7, 2010 Posts: 0 Comments: 5725
69. 7544
hwrf still takes 92L to so fla will the others follow Link
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Quoting TORMENTOSO83:
Igor is gonna strike PR!!!


No it's not!!!
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Quoting hunkerdown:
sure it will cause it will more than likely the earliest to recurve and scoot on out of the picture...
Luckily yeah, it should continue to move towards the W/WNW over the next day or two. It should then start to move poleward and head on out to sea.
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66. MZT
I will agree that 92L could achieve "Alex-like" proportions if it continues to organize as it has been doing.

My gut says TD by 5PM advisory.
Member Since: September 24, 2005 Posts: 0 Comments: 793
Thanks DRM. I hope Igor goes harmlessly out to sea. It's just hard to put all your faith in the GFS for steering when it doesn't even show 92l as developing. UGH! It does get confusing. But I hope gfs is correct about that too. Because I don't see 92l making a clean get away no matter the intensity. And just that amount of rainfall can be devastating on its own. :(
Member Since: August 24, 2010 Posts: 0 Comments: 252
Quoting MiamiHurricanes09:
It won't look cute 3 days from now...lol.


Yeah, but neither will I.
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Quoting 7544:
like i said yesterday 92l was getting jelous of igor look at her now is she starting to drift wnw or west tia
WNW.
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Quoting TreasureCoastFl:


That's ignorance for ya..


+1

Have to go; be back in an hour.
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Re: 52
Not everybody..He's not makin' me mad.
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Quoting TropicalAnalystwx13:


Tropical Weather Blog Heat Potential

lol
Member Since: July 7, 2010 Posts: 0 Comments: 5725
C'mon Recurve. Here we go recurve.
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Quoting WeatherNerdPR:

What's TWBHP?


Tropical Weather Blog Heat Potential
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Quoting help4u:
Igor is a fish!Troughs will keep everything off east coast and everything in gulf will head west into mexico.Pattern has been set all year. I here everyone say next week pattern will change,this has been going on for 6 weeks and no change.If anything the pattern looks more set in stone for last half of season for all fish and busy season in mexico.Another reason people pay no attention to forcast they heard it a million times and nothing happens.


That's ignorance for ya..
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Good Morning!

92L continues to convectively get better organized, and may become a Tropical Depression later today.

Visible Satellite Loops Indicate a very well defined system; although cloud tops have warmed slightly, over the past hour. Impressive spiral banding developing with 92L as well. 93L also bears watching, as it has very impressive outflow, and is already symmetrical. The question is, which will become Julia and which will become Karl?
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53. 7544
like i said yesterday 92l was getting jelous of igor look at her now is she starting to drift wnw or west tia
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92L is one huge mother.
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CRS you really are trying to ruin my weekend
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Quoting TropicalAnalystwx13:
The TWBP is really low today.

What's TWBHP?
Member Since: July 7, 2010 Posts: 0 Comments: 5725
Quoting help4u:
Igor is a fish!Troughs will keep everything off east coast and everything in gulf will head west into mexico.Pattern has been set all year. I here everyone say next week pattern will change,this has been going on for 6 weeks and no change.If anything the pattern looks more set in stone for last half of season for all fish and busy season in mexico.Another reason people pay no attention to forcast they heard it a million times and nothing happens.


Thank You Mother Nature.

I'm glad you know what the tropics will do.
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Seems Dr. Masters was also noting the lack of surface circulation at present. The radar out of PR would have some sort of cyclonic curvature to the rain bands moving through the area if a defined surface circulation was already formed.

Not to say one couldn't form at anytime, conditions are right for it to occur, there just isn't one at present.
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Quoting Stormchaser2007:
Are there any Recon planes or GRIP missions planned for 92L?


Dr. Masters made note in his blog entry that the first recon is set for tomorrow (Sunday) afternoon, but that there is a research G-V flight scheduled for today.
Member Since: Posts: Comments:
Igor is a fish!Troughs will keep everything off east coast and everything in gulf will head west into mexico.Pattern has been set all year. I here everyone say next week pattern will change,this has been going on for 6 weeks and no change.If anything the pattern looks more set in stone for last half of season for all fish and busy season in mexico.Another reason people pay no attention to forcast they heard it a million times and nothing happens.
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93L lookin' kinda sporty...As is 92L and Igor...Hmmmm...
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The TWBHP is really low today.
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Could have TD 12 if convection can hold together.

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93 has really hit the water running! good outflow already. He looks better than 92 even!
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BEWARE! The SABP!
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Dr. Masters mentions the heavy squall that passed through San Juan...It hit me as a shower.
Member Since: July 7, 2010 Posts: 0 Comments: 5725
92L/INV/XX
MARK
14.83N/66.33W
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Quoting sngalla:
Thanks Dr M!


Hi ya Neighbor, good to see you again!
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Storm as you said earlier,the next waves do look like they are coming off Africa lower in latitude.Those are gonna be the ones to watch.JMO though.As for 92L Dr.M really sees it developing from a depression to a TS on Sunday or Monday.
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Showing my ignorance here, so please excuse me. How long will the 'ridge' (if that is correct) stay steady that is keeping storms from coming up more north into the GOM?
Member Since: August 22, 2009 Posts: 0 Comments: 3159
Quoting MiamiHurricanes09:
It won't look cute 3 days from now...lol.
sure it will cause it will more than likely the earliest to recurve and scoot on out of the picture...
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Quoting MiamiHurricanes09:
It won't look cute 3 days from now...lol.

lol
Member Since: July 7, 2010 Posts: 0 Comments: 5725
Quoting tropicfreak:


From the rules of the road.

Do not "1st!", "1st post!", or any of the numerical/linguistic derivatives. This is a worthless use of blog space.


Its okay, It was deleted.

Back to weather...
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Are there any Recon planes or GRIP missions planned for 92L?
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Quoting tropicfreak:


From the rules of the road.

Do not "1st!", "1st post!", or any of the numerical/linguistic derivatives. This is a worthless use of blog space.


Thanks. After 5 years I wasn't sure about the rules of the road. Its great to get a reminder from time to time.
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Quoting Stormchaser2007:
Most impressive wave I've seen in a while.

It hasn't even fully emerged yet,and the NHC has a code orange on it!.Reminds me of Bertha when she was over africa.
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Quoting WeatherNerdPR:

Kinda looks...Cute.
It won't look cute 3 days from now...lol.
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In my opinion at 5PM-8PM:

Igor becomes a hurricane. (5PM)

Invest 92L is declared TD #12 (5PM)

Invest 93L is upgraded to 50-70% (8PM)
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Quoting JupiterFL:


I think he was saying it was his first ever post on the blog. Welcome.


From the rules of the road.

Do not "1st!", "1st post!", or any of the numerical/linguistic derivatives. This is a worthless use of blog space.
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thanks for update doc lets get ready for a busy week ahead
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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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