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 tropiccian:
Hey TXCaneCrasher. What part of Tx are you in?


Victoria area....what about you?


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Quoting KoritheMan:


I'm wondering this too. I imagine he's just busy with life. He's married after all, I think.


And has a new little one. That will keep anyone busy.
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Good night. I'll wake up to see what happens to Hurricane Igor, and our 2 Invests.
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Quoting moonlightcowboy:



Agreed, too, Beell. The weakness is generally in the upper layers anyways, imo, and 92L would have to get his giddyup going to really get that tug. So, it'll move more westwards, but should get a natural coriolis bump a degree or two northwards as it cranks up.
one has referenced 92L and one 93L though I believe you are both talking 92L...
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Quoting cyclonekid:
Ok. Just Wondering. I see that Igor has strengthened into a hurricane. But, where has Weather456 been?


I'm wondering this too. I imagine he's just busy with life. He's married after all, I think.
Member Since: March 7, 2007 Posts: 596 Comments: 21029
Quoting Neapolitan:
Two reds, a yellow, and a hurricane...
Nice Grouping!
Member Since: August 3, 2005 Posts: 10 Comments: 5640
Quoting cyclonekid:
Ok. Just Wondering. I see that Igor has strengthened into a hurricane. But, where has Weather456 been?


Busy with family and other things.
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Quoting KerryInNOLA:
" Quoting zicoille:
Someone promised me Igor...I hope we will have it. Earl was joke !



You're gonna get a lot of flak for that. You understand that, right? Rightly so, perhaps.

But I also think that people shouldn't be so quick to judge such comments. I understand how you feel, and won't condemn you for it."

I'm watching you two. :)


I don't wishcast, if that's what you're thinking. I just forecast. ;)

I was just saying that I understand wanting a storm. I might get a lot of flak for this comment myself, but I sympathize with his desire. I don't desire to see destruction or loss of life, but there is a certain thrill to tropical cyclones.

IMO, there's nothing wrong with being thrilled about events like this. You have no control over them, so you shouldn't feel bad if your wish ends up coming to fruition.

Now, if he said that he enjoyed death and destruction, that'd be different. I despise both of those, and have cried in times of disaster before, and will no doubt do so again.
Member Since: March 7, 2007 Posts: 596 Comments: 21029
Hey TXCaneCrasher. What part of Tx are you in?
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1464. bassis
Cant keep my eyes open any longer to watch WV loops.

Really starting to enjoy the ignore button tonight
Member Since: September 8, 2008 Posts: 0 Comments: 423
Quoting Levi32:


If it were to gain enough latitude, then possibly, and they should keep an eye on it, but with the strong ridge remaining solidly in place near Texas for the next few days a hit on Mexico is more likely, if the system develops. It is still a ways off though.


Thanks Levi...your posts are always appreciated and respected. I live on the middle Texas coast so that was the reason for the question.
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1462. Levi32
Quoting moonlightcowboy:



Agreed, too, Beell. The weakness is generally in the upper layers anyways, imo, and 92L would have to get his giddyup going to really get that tug. So, it'll move more westwards, but should get a natural coriolis bump a degree or two northwards as it cranks up.


The weakness is very much present in the lower levels as well.

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Quoting kmanislander:
I'm out for now folks. May be back later but if not in the morning before golf LOL
Good night.
Member Since: October 9, 2008 Posts: 0 Comments: 8421
interesting hermine was a 65 mph ts with a pressure of 991 mb and igor now a hurricane has a pressure simliar 992 mb
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Ok. Just Wondering. I see that Igor has strengthened into a hurricane. But, where has Weather456 been?
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Quoting want2lrn:


btwntx08...about 127 miles north of you here. What are your thoughts on 92L for all of us in South Texas? I know it is early but just curious. Anyone else with knowledge be glad to listen
Refer to post #1450.
Member Since: October 9, 2008 Posts: 0 Comments: 8421
I'm out for now folks. May be back later but if not in the morning before golf LOL
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1456. Levi32
Quoting Drakoen:


The low level flow is very weak in the Caribbean


Yes.

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Quoting btwntx08:


btwntx08...about 127 miles north of you here. What are your thoughts on 92L for all of us in South Texas? I know it is early but just curious. Anyone else with knowledge be glad to listen
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CHIPS finally came around to match the other forecasts for Igor's near future. Lagging in intensity later, as compared to NHC and others.

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new Igor advisory now a hurricane winds 75 mph movement west....however the 5 day forecast is shifted to the right and it looks less likely it will hit the us
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...IGOR STRENGTHENS INTO A HURRICANE...THE FOURTH OF THE SEASON...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...17.7N 42.5W
ABOUT 1230 MI...1975 KM W OF THE CAPE VERDE ISLANDS
ABOUT 1275 MI...2050 KM E OF THE LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/HR
PRESENT MOVEMENT...W OR 275 DEGREES AT 17 MPH...28 KM/HR
MINIMUM CENTRAL PRESSURE...992 MB...29.29 INCHES
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" Quoting zicoille:
Someone promised me Igor...I hope we will have it. Earl was joke !



You're gonna get a lot of flak for that. You understand that, right? Rightly so, perhaps.

But I also think that people shouldn't be so quick to judge such comments. I understand how you feel, and won't condemn you for it."

I'm watching you two. :)
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1450. Levi32
Quoting TXCaneCrasher:


Levi, I know it is still way too early to tell but could Texas be a possiblity for 92L?


If it were to gain enough latitude, then possibly, and they should keep an eye on it, but with the strong ridge remaining solidly in place near Texas for the next few days a hit on Mexico is more likely, if the system develops. It is still a ways off though.
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I missed this bulleting. It was posted at 5pm.

Met Service of Jamaica Website
Saturday, September 11, 2010 – 5:00 p.m.

***Area of Low Pressure across southeastern Caribbean could develop into tropical cyclone...***



*** BROAD AREA OF LOW PRESSURE MOVING TOWARDS CENTRAL CARIBBEAN ***

A broad area of Low Pressure near the Windward Islands has become nearly stationary over the southeastern Caribbean Sea.

Satellite imagery indicates that the cloudiness and thunderstorms associated with the Low Pressure system remain disorganized. Conditions are; however, favourable for gradual development and a tropical cyclone could form during the next day or two as the system moves toward the central and western Caribbean Sea.

Locally, there is the potential for heavy showers with possible flash flooding as the system progresses closer to Jamaica by Monday.

Due to the current potential for the system to strengthen and move westward, small craft operators are specially advised that weather conditions are expected to experience steady deterioration on Sunday and Monday. Thundershowers and strong, gusty winds are forecast to develop over the period.

Fishers on the cays and banks, particularly south of the island, should be ready for quick evacuation should it become necessary. Those in port are strongly advised not to venture far from the mainland.

The Meteorological Service will continue to monitor the progress of this system and all interests should pay special attention to subsequent Releases.

The Meteorological Service will continue to monitor the progress of this system.
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93L looking very well organized if that trend continues we will probably have a td at 5 am
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000
WTNT41 KNHC 120233
TCDAT1
HURRICANE IGOR DISCUSSION NUMBER 15
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112010
1100 PM AST SAT SEP 11 2010

THE CLOUD PATTERN ASSOCIATED WITH IGOR HAS INCREASED IN ORGANIZATION
DURING THE PAST SEVERAL HOURS. A TIGHTLY-COILED BAND...WITH CLOUD
TOP TEMPERATURES TO -85C...WRAPS AROUND THE EASTERN SEMICIRCLE INTO
A DEVELOPING CENTRAL DENSE OVERCAST. AN EYE FEATURE HAS ALSO BEEN
BRIEFLY INTERMITTENT IN CONVENTIONAL SATELLITE IMAGERY...AND A
NUMBER OF MICROWAVE PASSES SEVERAL HOURS AGO REVEALED A DISTINCT
CONVECTIVE RING SURROUNDING THE CENTER. SUBJECTIVE DVORAK T-NUMBERS
AT 0000 UTC WERE A CONSENSUS 4.0 FROM BOTH SATELLITE AGENCIES...AND
3-HOURLY AVERAGED ADT VALUES FROM UW-CIMSS ARE 4.3. THE INITIAL
INTENSITY IS RAISED TO 65 KT THIS ADVISORY...MAKING IGOR THE FOURTH
HURRICANE OF THE 2010 ATLANTIC HURRICANE SEASON. THE UNDERLYING
OCEAN ONLY GETS WARMER ALONG THE FORECAST TRACK OF IGOR...PEAKING
AROUND 29C IN ABOUT 3 DAYS. THAT...COMBINED WITH A LIGHT SHEAR
ENVIRONMENT...WOULD FAVOR A STRENGTHENING TREND FOR THE NEXT FEW
DAYS...AND NEARLY ALL THE INTENSITY GUIDANCE MAKES IGOR A MAJOR
HURRICANE BY 72 HOURS. THEREAFTER...WHILE FLUCTUATIONS IN INTENSITY
MAY OCCUR...IGOR IS EXPECTED TO MAINTAIN MAJOR HURRICANE STATUS AND
BE A LARGE HURRICANE OVER THE CENTRAL NORTH ATLANTIC.

IGOR HAS MAINTAINED ROUGHLY THE SAME MOTION...275/15...THOUGH
PERHAPS A TAD SLOWER THAN EARLIER. SUBTROPICAL RIDGING NORTH OF
THE CYCLONE SHOULD BE THE DOMINANT STEERING FEATURE FOR THE NEXT 2
TO 3 DAYS...CARRYING IGOR ON A GENERAL WESTWARD TRACK. BEYOND THIS
TIME...DYNAMICAL MODELS SHOW IGOR SLOWING AND TURNING WEST-
NORTHWESTWARD AS IT APPROACHES AND THEN MOVES INTO A SUBSTANTIAL
BREAK IN THE SUBTROPICAL RIDGE. AS WAS THE CASE IN THE PREVIOUS
MODEL CYCLE...THERE CONTINUES TO BE CONSIDERABLE SPREAD IN THE
TRACK GUIDANCE...WITH THE GFDL/HWRF THE RIGHTMOST OF MODEL
SOLUTIONS AND THE UKMET/NOGAPS THE LEFTMOST. THESE DIFFERENCES
SEEM TO HINGE ON THE STRENGTH AND POSITION OF THE SUBTROPICAL
RIDGE...WITH THE FORMER MODELS FORECASTING A WEAKER RIDGE DISPLACED
TO THE EAST WHILE LATTER INDICATE A MORE ROBUST RIDGE EXTENDING
FARTHER WEST. THE OFFICIAL NHC FORECAST TRACK HAS BEEN ADJUSTED TO
THE RIGHT...FOLLOWING THE TREND IN THE GUIDANCE... BUT IS NOT AS
FAR RIGHT AS THE MULTI-MODEL CONSENSUS.


FORECAST POSITIONS AND MAX WINDS

INITIAL 12/0300Z 17.7N 42.5W 65 KT
12HR VT 12/1200Z 17.8N 44.8W 75 KT
24HR VT 13/0000Z 17.9N 47.4W 80 KT
36HR VT 13/1200Z 18.1N 49.7W 90 KT
48HR VT 14/0000Z 18.4N 51.9W 100 KT
72HR VT 15/0000Z 19.5N 55.0W 110 KT
96HR VT 16/0000Z 21.5N 58.0W 115 KT
120HR VT 17/0000Z 23.5N 61.0W 115 KT

$$
FORECASTER KIMBERLAIN
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1446. Drakoen
Quoting beell:
I'd tend to line up with Kman on 93L (hey, look! i agreed w/somebody!). It is still a low level disturbance and the low level flow may be brisk enough to send it on west.


The low level flow is very weak in the Caribbean
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Quoting beell:
I'd tend to line up with Kman on 93L hey, look! i agreed w/somebody!). It is still a low level disturbance and the low level flow may be brisk enough to send it on west.



Agreed, too, Beell. The weakness is generally in the upper layers anyways, imo, and 92L would have to get his giddyup going to really get that tug. So, it'll move more westwards, but should get a natural coriolis bump a degree or two northwards as it cranks up.
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...IGOR STRENGTHENS INTO A HURRICANE...THE FOURTH OF THE SEASON...
11:00 PM AST Sat Sep 11
Location: 17.7°N 42.5°W
Max sustained: 75 mph
Moving: W at 17 mph
Min pressure: 992 mb
Member Since: July 8, 2005 Posts: 259 Comments: 24458
Quoting Drakoen:


Very close to tropical depression status with T# of 1.5 from both agencies at 00z.
Hard to dismiss the sat. presentation. The entire EALT environment is moistening significantly, judging from the WV.
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1442. MZT
92L was a great lesson today why the NHC will take their time declaring things... lots of us here were itching to call it a TD around 11AM this morning.

I think KmanIslander nailed it though pointing out the discrepanacy between lower and upper levels. The system lacked the re-convective nature that it needed to stay energized.
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...IGOR STRENGTHENS INTO A HURRICANE...THE FOURTH OF THE SEASON...
--------------------------------------------------------------------------------

11:00 PM AST Sat Sep 11
Location: 17.7°N 42.5°W
Max sustained: 75 mph
Moving: W at 17 mph
Min pressure: 992 mb

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1440. Levi32
Recent microwave pass of Igor shows a well-defined eye wall nearly closed off.

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Cat. 5, anyone?
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...IGOR STRENGTHENS INTO A HURRICANE...THE FOURTH OF THE SEASON...
Member Since: March 7, 2007 Posts: 596 Comments: 21029
Quoting Levi32:


It won't buck it but it hasn't gotten to that point yet in my opinion. There's still a little way to go yet before 92L will be forced to turn west, and it may very well take its sweet time if the weakness is strong enough, because it's darn hard to turn a tropical system southwest. The track likely won't turn that hard left but it's still going to take some effort to pull 92L away from the weakness.


Levi, I know it is still way too early to tell but could Texas be a possiblity for 92L?
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Two reds, a yellow, and a hurricane...
Member Since: November 8, 2009 Posts: 4 Comments: 13597
Very near depression status.

Cape Verde islands should see some squalls.

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All my fellow Canes fans, today was a terrible day, as we lost......to Ohio State. Oh well, they come here next year. As for Igor, that's a nice looking hurricane and I don't see this recurving, and it kinda looks like the NHC is agreeing.
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What didStormW mean in post 1391 that the "bottom of the trough" was starting to open up? I have a rough idea, but can someone please explain that comment?
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Quoting Levi32:
Invest 93L looks remarkably good for how close it is to Africa.


That is one scary picture. I need to go take an asprin now.
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1431. beell
I'd tend to line up with Kman on EDIT: 92L (hey, look! i agreed w/somebody!). It is still a low level disturbance and the low level flow may be brisk enough to send it on west.
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Quoting stormwatcherCI:
The blog is great tonight. Some fantastic heads on here debating and this is how we learn. Thanks Storm, Kman, Kori, Drak, Levi and the rest of the knowledgable folks on here.


Can I get a BIG "AMEN" for that! I totally agree. This is the most I've enjoyed this blog in awhile and I'm sucking up all the info and insight I can get. Thanks to you all. ~ K
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200mb level depicts the weakness and trough positions well.
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1428. Levi32
Experimental FIM Global model (similar to the GFS) shows a fairly westerly track for Igor, bringing tropical storm conditions up to the Carolinas and then running north towards New England.

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Quoting zicoille:
Someone promised me Igor...I hope we will have it. Earl was joke !

I was thinking about pounding you about reasons Earl was no joke, but I have decided not to. The reason is that I don't want either of us to circumvent a ban. Get it now?
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Quoting KoritheMan:


I suspected he'd be around 70 kt at 11:00 PM.


Yeah, the FTP site has it as 65 knots now, so we'll see what happens.

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1425. Drakoen
Quoting Levi32:
Invest 93L looks remarkably good for how close it is to Africa.


Very close to tropical depression status with T# of 1.5 from both agencies at 00z.
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Quoting zicoille:
Someone promised me Igor...I hope we will have it. Earl was joke !
Careful what you wish for. Don't think you want any of that one.....
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Quoting WeatherNerdPR:

Yeah, unless they turn into trolls, which isn't gonna happen. For now. lol


Nah, those guys will never be trolls. They're far above that.
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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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