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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Lots of imposters out tonight. Looks like Igor is going to be a beast of a storm.
Member Since: Posts: Comments:
Quoting want2lrn:
Okay..what is the mona passage AND if fronts are starting to move across, wouldn't that allow or pull or whatever the correct terminology is 92L farther N? Possibly causing problems for the gulf coast?


Got the mona passage part (love google) but what about part two? TIA
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Quoting jurakantaino:
Just a little thinking, I wonder if those mets and scientist that talk about a hyper season, didn't count with SAL and dry air to be the #1 inhibitor for this season. You see that all the storms even those like Earl or Dannielle had to deal with SAL, some made it others fizzel like Gaston, 92L is struggling with dry air. Igor, well he is a figher dealing with dry air...and will probably win the fight.
92L struggling with dry air?http://www.ssd.noaa.gov/goes/east/carb/flash-wv.html
Member Since: July 21, 2008 Posts: 0 Comments: 348
Quoting Eugeniopr:


It is bad for the blog because if there is not a threat you get bored.

thanks for that bit of information, are you in control of the board or somthing? dont take that the wrong way.
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1215. pottery
Quoting jurakantaino:
Just a little thinking, I wonder if those mets and scientist that talk about a hyper season, didn't count with SAL and dry air to be the #1 inhibitor for this season. You see that all the storms even those like Earl or Dannielle had to deal with SAL, some made it others fizzel like Gaston, 92L is struggling with dry air. Igor, well he is a figher dealing with dry air...and will probably win the fight.

SAL was not really the problem, but dry air certainly was. Shear was a contributing factor in some of the systems too.
But I dont think that the forecasts predicted dry air to be such an issue, you are correct in that. In fact, the Sahel region was predicted to be on the 'wet' side, helping to promote development.
So, what went wrong with the forecasts?
Member Since: October 24, 2005 Posts: 0 Comments: 23080
And to those who know their STUFF on the blog, I must say I really appreciate the info. Also,
thanks for putting up with me! lol
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Member Since: Posts: Comments:
Storm..... a question

On your blog from earlier today you have a wave over west Africa circled in red... This seems to be coming off of Africa much further south than the previous few storms.

If my memory is correct, some time ago you mentioned that a storm coming off of Africa this far south would be THE ONE to really be concerned about....

Your thoughts ??

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Quoting pottery:
JASON>>>
I am sorry. I cannot bear your caps anymore.
'bye.
Agree on J. I tried too.
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Quoting Tazmanian:



this is for 93L


AL, 93, 2010091200, , BEST, 0, 128N, 185W, 25, 1006,


Thanks, Taz. Yeah, that's pretty healthy looking, too.

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1208. Walshy
Don't quote the trolls. Your intelligence is beyond help for them...




93L looking very good atm
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Quoting bassis:
Kori
great job on your blog!!


Thanks! I love to do it, and will one day be an actual meteorologist.

Though I must say, these active tropics are starting to give me a headache. LOL!

I need a break. haha
Member Since: March 7, 2007 Posts: 521 Comments: 19119
Chill out guys, the second trough is probably not the trough that will recurve Igor, it's the third one, may not even recurve until Igor is too close for comfort. The first trough does NOTHING with Igor, the seocnd trough lifts Igor NW towards Bermuda, then slows down as a ridge builds in back of the storm and it's THAT ridge that the model runs are having fun with. Some of them strengthen the ridge like the NOGAPS, CMC, and HWRF and keep Igor moving NW instead of recurving. Some models have a weak High like the GFS, EURO, and GDFL and slpit ti up while Igor moves north and busts through it. May thing can happen. So that's my thinking on the situation. The GFS shows the third trough, small, but potent, taking Igor away from the USA, but will Igor make it all the way in time? That is the question.
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Okay..what is the mona passage AND if fronts are starting to move across, wouldn't that allow or pull or whatever the correct terminology is 92L farther N? Possibly causing problems for the gulf coast?
Member Since: Posts: Comments:
Just a little thinking, I wonder if those mets and scientist that talk about a hyper season, didn't count with SAL and dry air to be the #1 inhibitor for this season. You see that all the storms even those like Earl or Dannielle had to deal with SAL, some made it others fizzel like Gaston, 92L is struggling with dry air. Igor, well he is a figher dealing with dry air...and will probably win the fight.
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1203. bassis
Kori
great job on your blog!!
Member Since: September 8, 2008 Posts: 0 Comments: 423
Quoting weatherwart:


OH,

Oh. Well, that answers one question.



this is for 93L


AL, 93, 2010091200, , BEST, 0, 128N, 185W, 25, 1006,
Member Since: May 21, 2006 Posts: 5089 Comments: 114049
Quoting jacechase:

lol thanks for that, am i off that much???
and I dont see what you said that could be bad for the blog btw.


It is bad for the blog because if there is not a threat you get bored.
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Quoting GeoffreyWPB:
Going out on a huge limb here...I think it is possible that 92L will make a run towards the Mona Passage.
THAT would not be a good thing to have happen!
Member Since: July 21, 2008 Posts: 0 Comments: 348
1198. Drakoen
Quoting MoltenIce:
92L = 60%
93L = 70%

Looks like 93L is winning the name "Julia". But it's to early too tell.


93L will win
Member Since: October 28, 2006 Posts: 57 Comments: 29714
92L = 60%
93L = 70%

Looks like 93L is winning the name "Julia". But it's to early too tell.
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Quoting doorman79:


Some people aren't happy until a major slams our coast so they can watch the news! Hate to say it but its the only way they can justify in their minds that is or is not an active season.

Hope that one doesn't get me banned lol!


Me too
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Quoting StormW:


Once it crosses 75W
Thanks
Member Since: July 21, 2008 Posts: 0 Comments: 348
Quoting doorman79:


Some people aren't happy until a major slams our coast so they can watch the news! Hate to say it but its the only way they can justify in their minds that is or is not an active season.

Hope that one doesn't get me banned lol!


+1

Would read again.
Member Since: March 7, 2007 Posts: 521 Comments: 19119
Quoting Eugeniopr:


Yes as predicted by NHC
Quoting Relix:


I think it was around this time we started this discussion last night haha

lol thanks for that, am i off that much???
and I dont see what you said that could be bad for the blog btw.
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OH,
Quoting Tazmanian:
AL, 11, 2010091200, , BEST, 0, 176N, 419W, 65, 992, HU,


Oh. Well, that answers one question.
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1191. Drakoen
Very near Tropical Depression Status

Member Since: October 28, 2006 Posts: 57 Comments: 29714
Going out on a huge limb here...I think it is possible that 92L will make a run towards the Mona Passage.
Member Since: September 10, 2007 Posts: 0 Comments: 10577
Quoting jason2010xxxx:
HERE ITS COME THE COLD FRONTS WILL SAVE USA FROM ANY HURRICANE HITTING THE USA.. GOOD TIMING.


Your are spoiling the blogers needs of a real catastrophe. But I think and hope you are right.
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Look at that eye! lol
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Good evening everyone. I see things are popping all over the place. Do we have a hurricane, yet? Igor is looking pretty good. For that matter, 92L is starting to pull together some, too.
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AL, 93, 2010091200, , BEST, 0, 128N, 185W, 25, 1006, DB
Member Since: May 21, 2006 Posts: 5089 Comments: 114049
1184. beell
Quoting jacechase:
To me it looks like Igor is starting to move a bit south of due west, anyone else see that?


a "nope" opinion over the last 6-7 hrs.

Link
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Quoting FLGatorCaneNut:


Do me big favor... go back to 2005 and see what a cold front did with Wilma and the USA..... Not all fronts save the USA !!!


and while your back there, find the caps lock button that fell off your keyboard.
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AL, 11, 2010091200, , BEST, 0, 176N, 419W, 65, 992, HU,
Member Since: May 21, 2006 Posts: 5089 Comments: 114049
Quoting StSimonsIslandGAGuy:


Alex hit as a strong Cat 2. Earl brought hurricane force winds to the northern Leewards and gales from North Carolina to Newfoundland. Hermine killed 6 people in Texas and Oklahoma. We have had 2 Cat 4 hurricanes already, and are ahead of schedule on number of storms and ACE.


Some people aren't happy until a major slams our coast so they can watch the news! Hate to say it but its the only way they can justify in their minds that is or is not an active season.

Hope that one doesn't get me banned lol!
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1180. pottery
Quoting Eugeniopr:


Relix, you are correct but your opinion is not good for the blog.

What can this mean?
Member Since: October 24, 2005 Posts: 0 Comments: 23080
Good evening all. Question for StormW please.
StormW, it looked like earlier today 92L was/might break the John Hope rule and start really ramping up in the eastern Caribbean. Since earlier today it's lost most of deep convection. At what point/degree westward would you consider "out" of the eastern Caribbean, and be "in" the western Caribbean?
Member Since: July 21, 2008 Posts: 0 Comments: 348
Quoting StormW:


The circulation is starting to wind up:

LINK
I see it but just to be sure. Just to the east of 68W and around 15.? N
Member Since: October 9, 2008 Posts: 0 Comments: 8242
Out of lurk mode to make an observation. If it is incorrect please say so, as i am trying to learn. It appears to me that just south of what appears to be thunderstorms? (red dot) i think that i see the circulation starting to look better. Am i correct and would this be a low level or mid level feature? TIA
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Quoting Relix:
If Anything Igor is sightly north of the forecast points.


Relix, you are correct but your opinion is not good for the blog.
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Quoting jason2010xxxx:
HERE ITS COME THE COLD FRONTS WILL SAVE USA FROM ANY HURRICANE HITTING THE USA.. GOOD TIMING.


Do me big favor... go back to 2005 and see what a cold front did with Wilma and the USA..... Not all fronts save the USA !!!
Member Since: Posts: Comments:

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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.

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