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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Quoting washingtonian115:
His track looks like a backwards 7.And you can obviously see what was steering him.Which was probally a big high pressure system.
I don't know what was steering him but that is the first hurricane my children experienced. South Sound(the area kman and stormpetrol live) did not even have a road left.
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722. Relix
Really. I won't get into this "WSW!!!!" discussion, but Igor is moving due west. I would say he's actually around 17.4N now. Just on track. There's no WSW movement as there was none last night. It's due WEST.
(modified LAT mistake heh)
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Hmmmm...an interesting prospective on the tropics with a TX/LA slant from Lake Charles, La NWS. Link
Member Since: August 24, 2010 Posts: 0 Comments: 253
Quoting stormwatcherCI:
His track looks like a backwards 7.And you can obviously see what was steering him.Which was probally a big high pressure system.
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Quoting weathergeek5:
Storm or whoever:

Have a a few questions


1. Have you ever wished to experience a hurricane?

2. Did your opinion of hurricanes change after you experienced it?

3. What changes did you make after the experience of the hurricane?


1. Yes when I was young and stupid.
2. YES, scariest night of my life.
3. I evacuate, I'm prepared to be self sufficient for over a month.
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BTW: what, again, does he mean by glibertish? He used it earlier, too... ;-)

That is Glib Gibberish ...
such as:

obiovsly
elinate subjectivity
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Quoting Neapolitan:


Not sure how this would be any better or more subjective. I can see it being used as another metric, but certainly not replacing ACE. With Bastardi's scheme, there's no accounting for longevity; a monster storm that stayed as a Cat 3 for, say, a week straight would be considered weaker than a TS that goes through RI, jumps to Cat 4 for one TWO, then dissipates 48 hours after being named. I'm not sure how such a metric would be superior to anything we have now...

BTW: what, again, does he mean by glibertish? He used it earlier, too... ;-)
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Igor was at 17.1N and now it looks like 17.0 N....
Is this correct????
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Quoting SherwoodSpirit:
I was watching the "Wavy Train" in Africa for a few days before 99L was designated. The wave that became 99L (if I'm remembering right) caught up to another wave ahead of it near the coast, and they appeared to spin around each other and merge, then exited the coast, where they became 99L. At that time, there still appeared to be two areas of spin, one north and 99L to the south. 99L headed west from there, and that northern spin is, I believe, what we're now seeing at about 30N, 50W.


Its a mostly barotropic (more tropical than frontal) system being fed by low level feeds of moisture from the south and east. The Sea surface temperatures in the area are 25-26C so borderline for tropical formation. It looks like it will be absorbed by the front to the W in the next day.
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713. Kearn
Not looking too fun for Bermuda right now.

http://www.nhc.noaa.gov/graphics_at1.shtml?5-daynl#contents
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Quoting stormwatcherCI:
I think he means Gilbertish in regards to the location 92L is attempting to organize.


Yeah, a Gilbert-like track. He needs to turn on his spell-checker.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
Quoting reedzone:
Some strong disagreement on the ensembles and model runs for something that is "supposed" to recurve out to sea.
Maybe the models disagree,about his forward speed,or when the trof is suppose to arrive,and how strong it will be.
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Quoting Neapolitan:


Not sure how this would be any better or more subjective. I can see it being used as another metric, but certainly not replacing ACE. With Bastardi's scheme, there's no accounting for longevity; a monster storm that stayed as a Cat 3 for, say, a week straight would be considered weaker than a TS that goes through RI, jumps to Cat 4 for one TWO, then dissipates 48 hours after being named. I'm not sure how such a metric would be superior to anything we have now...

BTW: what, again, does he mean by glibertish? He used it earlier, too... ;-)
I think he means Gilbertish in regards to the location 92L is attempting to organize.
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Quoting washingtonian115:
For the love of god,please stop protesting.We get our point.



and plzs stop Quoteing him
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Quoting washingtonian115:
Taz I think thir is more named storms than that.



nop 6 name storms for the E PAC so far and i think they will not see a other name storm
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Quoting Joe Bastardi:
I dont like the ACE index. Its too subjective. Its sticks in my craw when I see storms like the 947 mb Alex, obiovsly a major hurricane, given only 85 kts. So my proposal and this is the 3rd major proposal I have, the others being the power rating and the naming criteria, is that we total up the pressures of all storms set against 1000mb and rate the season that way.

By that I mean a 945 mb huricane gets 55 points a 925 75 pts. Anything above 1000 mb named doesnt get any rating. By doing this we once again elinate subjectivity and get a good look at what the atmosphere was really up too.

In the Pacific, the scale would be set to 990 mb since the mean pressures are lower...

by joe b


Not sure how this would be any better or more subjective. I can see it being used as another metric, but certainly not replacing ACE. With Bastardi's scheme, there's no accounting for longevity; a monster storm that stayed as a Cat 3 for, say, a week straight would be considered weaker than a TS that goes through RI, jumps to Cat 4 for one TWO, then dissipates 48 hours after being named. I'm not sure how such a metric would be superior to anything we have now...

BTW: what, again, does he mean by glibertish? He used it earlier, too... ;-)
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Quoting Cat5Survivor:
stormpetrol,

This is only my second post, the first having been ignored, I suspect because I never addressed it specifically to anyone. Either that or all the posters on here are related to my wife.

Anyway, would you have a look at post #518 and tell me if I am missing something?

TIA
Do not feel like you are being ignored. Although I cannot answer your question I just want to tell you as long as there is something out there to track the blog will get busy and sometimes your question is overlooked.
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Some strong disagreement on the ensembles and model runs for something that is "supposed" to recurve out to sea.
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Quoting CybrTeddy:
Igor predicted to peak at 135 mph now.
Quoting Tazmanian:
WOW the E PAC may olny end up with 6 name storms this year
Taz I think thir is more named storms than that.
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looks like we got mode runs for 93L

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Quoting Txwxchaser:
In looking at satellites, it looks like 92L lined up parallel to Igor and soon to be 93L. Is 92L an ITCZ storm?


Yes
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Igor forecast to be a
Category 4 Hurricane
when offshore of us in the Turks and Caicos
on Thursday...

This sounds familiar.

CRS
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Quoting Vero1:


True but it is always correct. And you know that your are facing trouble when it is pointing directly at you prior to landfall.
not really cause that is the extrapolated motion over the PAST 12 hours. If there is a feature that will effect the present or future path of the storm, the XTRP will not show any change in motion from that feature.
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In looking at satellites, it looks like 92L lined up parallel to Igor and soon to be 93L. Is 92L an ITCZ storm?
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stormpetrol,

This is only my second post, the first having been ignored, I suspect because I never addressed it specifically to anyone. Either that or all the posters on here are related to my wife.

Anyway, would you have a look at post #518 and tell me if I am missing something?

TIA
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691. Relix
000
WTNT41 KNHC 112038
TCDAT1
TROPICAL STORM IGOR DISCUSSION NUMBER 14
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112010
500 PM AST SAT SEP 11 2010

IGOR IS VERY CLOSE TO BECOMING A HURRICANE. SATELLITE IMAGES SHOW
THAT CONVECTION HAS INCREASED AROUND THE CENTER AND HAVE RECENTLY
SUGGESTED THAT AN EYEWALL COULD BE FORMING. ALTHOUGH MOST OF THE
INTENSITY ESTIMATION TECHNIQUES SUGGEST IGOR IS A HURRICANE...IT IS
PREFERABLE TO WAIT AND SEE IF THE CONVECTION STICKS AROUND AND TO
GET MICROWAVE CONFIRMATION OF THE INNER CORE STRUCTURE.

MOST OF THE ENVIRONMENTAL FACTORS NEAR THE CYCLONE SEEM RATHER
CONDUCIVE FOR STRENGTHENING. GLOBAL MODELS ALL BUILD AN UPPER
ANTICYCLONE JUST TO THE NORTH OF IGOR...A RATHER FAVORABLE PATTERN
FOR THE DEVELOPMENT OF A MAJOR HURRICANE. SSTS AND OCEAN HEAT
CONTENT ALSO INCREASE STEADILY ALONG THE FORECAST TRACK. THE MOST
OBVIOUS INHIBITING FACTOR IS PERHAPS A WEDGE OF DRIER AIR THAT HAS
WORKED ITS WAY INTO THE NORTHERN PART OF THE CIRCULATION.
HOWEVER...THAT DRY AIR PROBABLY WILL NOT BE ABLE TO MAKE IT INTO
THE INNER CORE WITHOUT SOME SHEAR...AND THAT DOES NOT SEEM LIKELY AT
THIS TIME. THUS...THE INTENSITY FORECAST IS RAISED FROM THE
PREVIOUS ONE...BUT PEAKS BELOW THE LGEM AND SHIPS MODELS. IT IS OF
NOTE THAT ALL OF THE GLOBAL MODELS SHOW THE DEVELOPMENT OF A LARGE
AND POWERFUL HURRICANE...AND THE FORECAST WIND RADII HAVE BEEN
INCREASED.

IGOR REMAINS ON TRACK AND IS MOVING 275/16. THE SYNOPTIC STEERING
FOR THE NEXT SEVERAL DAYS APPEARS WELL DEFINED WITH A RIDGE TO THE
NORTH OF THE TROPICAL CYCLONE GUIDING THE CYCLONE GENERALLY
WESTWARD. HOWEVER...THE STRENGTH OF THIS RIDGE IS CRITICAL TO WHEN
IGOR BEGINS A MORE WEST-NORTHWEST MOTION. THE MODELS THAT MOVE THE
STORM FASTER TO THE WEST INITIALLY...SUCH AS THE NOGAPS OR
UKMET...ALLOW IGOR TO GET A LITTLE CLOSER TO THE NORTHERN LEEWARD
ISLANDS BEFORE MAKING A WEST-NORTHWEST TURN IN TWO OR THREE DAYS.
HOWEVER...ANOTHER GROUP OF MODELS...INCLUDING THE GFS/GFDL
SOLUTIONS...SHOW THAT TURN OCCURRING IN THE NEXT DAY OR TWO. THE
MODEL SPREAD HAS INCREASED SINCE THE LAST ADVISORY...AND I HAVE
ELECTED NOT TO CHANGE THE FORECAST MUCH...WHICH REMAINS TO THE
SOUTH AND WEST OF THE DYNAMICAL MODEL CONSENSUS FOR NOW.


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Quoting seflagamma:


Hi Taz, you are back!



i will be on and i will be off but i will still be a round
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Quoting IKE:
4 TD's allowed in 22 minutes by the Noles.



Fortunately for the islands, Igor is somewhat further north than Earl was at the same longitude.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
Quoting IKE:


Apparently to him it was. I'm not sold on it because the GFS...CMC and NOGAPS don't do much with it. Similar to Gaston and they were correct on it.
ECMWF keeps 92L at 1006 mb's crossing the Yucatan and then lowers it to 1003 mb's before hitting Mexico.


Got to remember something Ike, this is completely different than Gaston. Gaston was a Cape Verde system battling extremely dry air. This is different, this is a monsoonal disturbance popping out of the ITCZ and attempting to develop in the Caribbean, the models had a hard time with this when that seemed to be the only way systems where developing back in June. You may remember how Alex formed, this is somewhat similar and much more complex than Cape Verde development, the computer models are going to drop this and gain it. I think the ECMWF 'might' have the best handle, showing a 1007 mb low hitting the Yucatan (that's about 1003 mb, or a weak TS or a TD) before becoming a TS in the BOC. This will move slow, and has good environmental conditions ahead of it with good outflow being established over it, heading over the highest amount of TCHP in the Atlantic.
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Quoting Tazmanian:
this has a 5% ch of be comeing a cat 5 in 72hr is is by far the high has i evere seen it go so far this year



Hi Taz, you are back!
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WOW the E PAC may olny end up with 6 name storms this year
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Quoting CybrTeddy:
Igor predicted to peak at 135 mph now.
I think it could get stronger.Similar to Earl.
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684. IKE
4 TD's allowed in 22 minutes by the Noles.

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Quoting Tazmanian:
this has a 5% ch of be comeing a cat 5 in 72hr is is by far the high has i evere seen it go so far this year


wow
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Quoting xcool:


where is that high moving,?
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Quoting weathergeek5:
Storm or whoever:

Have a a few questions


1. Have you ever wished to experience a hurricane?

2. Did your opinion of hurricanes change after you experienced it?

3. What changes did you make after the experience of the hurricane?


1. Five of my college buddies, plus myself, decided to have a hurricane party at a hotel during Opal, with plenty of help from alcohol & .... uuh, cigarettes.

2. Can't remember.

3. Can't remember.
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Quoting RufusBaker:
Igor= FIsh
92L=Not a GOW storm
93L= Total fish (what happened to the high??)
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this has a 5% ch of be comeing a cat 5 in 72hr is is by far the high has i evere seen it go so far this year

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676. IKE
Quoting washingtonian115:
well get use to it,becuase I for one don't see it stopping for as long as this blog continues.


That's true too.
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675. IKE
Quoting watchingnva:
some on here r way too uptight....geez


That is true.
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674. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting watchingnva:
some on here r way too uptight....geez
well get use to it,becuase I for one don't see it stopping for as long as this blog continues.
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About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.