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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galvestonhurricane you must ha gone mad dead 92L is nowhere near that
Member Since: June 13, 2009 Posts: 2 Comments: 11215
I am probably leaving for the night; got to wrap up my work week and head home in about 20 mins.. YEAH!

everyone have a good evening and I know I will check in first thing in the morning.
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Quoting kmanislander:


The John Hope rule is very simple but verifies time and time again. If a tropical system does not develop into a tropical depression before entering the Eastern caribbean it is unlikely to do so before reaching the Western Caribbean.

I once looked at 30 years of data to see how this verified and found that in all those years there were only 8 or 9 systems that beacme TDs in the Eastern Caribbean including half of them from lows on the tail end of late season cold fronts. That left us with about 4 or 5 systems that managed to become TDs in the Eastern Caribbean over a 3 decade period.

I would say that is strong validation of the Rule.

Oh. Ok. Thanks. So one storm that kind of contradicts that is Hurricane Omar 2008?

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Quoting plywoodstatenative:
Hey Gamma, have you seen or heard from Hurricane Crab at all?


He checks in sometimes on a blog here or there... he checked in Foxx's blog not too long again and give us alittle update.

Since Paloma in Nov 2008 blew away his little Brac, he has been off line alot more than Pre-Palmoa....

plus been so busy the last 2 years rebuilding the island.

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Pin-hole poof taz for 92l!
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Kman,

I am a newbie here. I posted earlier and did not get an answer ( a statement, not a complaint!).

Would you do me a favour and look at post 518? Trying to learn and interested in what I am missing.

TIA
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Thanks Kman,

I have read that on here a many of times, Just never knew It was the John Hope rule!
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Quoting AtHomeInTX:


SmileyCentral.com Do I have to?



lol.... :) all those different faces.
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902. galvestonhurricane 3:33 PM PDT on September 11, 2010 Hide this comment.
RIP 92L
Action: Quote | Ignore User


POOF
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Quoting Txwxchaser:
#877. Ok, with all that, if Igor gets to be the monster storm some predict, is it possible that hurricanes that size and powerful can make their own path...I mean it seems to me that the forward motion of something that big would take some doing to stop it in its tracks and force it in diff direction. Maybe I've missed this explanation before...but just wondering since still so much uncertainty


it cant break through a High that is not eroded no matter how strong he is
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Quoting StormW:


When maximum sustained winds reach a minimum of 74 mph. J/K

a
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Hey Gamma, have you seen or heard from Hurricane Crab at all?
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Quoting doorman79:


Having trouble finding it. Got the short version by any chance.


The John Hope rule is very simple but verifies time and time again. If a tropical system does not develop into a tropical depression before entering the Eastern caribbean it is unlikely to do so before reaching the Western Caribbean.

I once looked at 30 years of data to see how this verified and found that in all those years there were only 8 or 9 systems that beacme TDs in the Eastern Caribbean including half of them from lows on the tail end of late season cold fronts. That left us with about 4 or 5 systems that managed to become TDs in the Eastern Caribbean over a 3 decade period from Easterly waves.

I would say that is strong validation of the Rule.

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Quoting reedzone:
12Z GFS 60 hours..


18Z GFS 48 hours (still running)


Little quiz time :P
There's a signifigant change on the 18Z, anyone like to show me what the change could be?
I'll play. I think there will be a slight trend westward, due to a weaker troff, at least based on the two model runs you posted. What do I win?
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Quoting Cregnebaa:
Happy Ivan Anniversary Kman!


Creg, so good to see you again, Been missing you around here during the "season".. hope all is well with you.
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Quoting StormW:


When maximum sustained winds reach a minimum of 74 mph. J/K


Storm,
Your sense of humor matches those awesome glasses lol! JOKE

Evening!
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#877. Ok, with all that, if Igor gets to be the monster storm some predict, is it possible that hurricanes that size and powerful can make their own path...I mean it seems to me that the forward motion of something that big would take some doing to stop it in its tracks and force it in diff direction. Maybe I've missed this explanation before...but just wondering since still so much uncertainty
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RIP 92L
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Storm I do believe that Igor, presentation alone, is a Hurricane. As for where he is headed, he has already shown erratic movements, so who knows where he is going.
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Quoting Legion:
I always wondered why it is that a lot of people praise the John Hope rule but you see so many mocking the Hebert boxes? Paul Hebert was a very knowledgeable meteorologist also, and his boxes are worthy of merit too, the proof is in the pudding.
What's the John Hope rule?
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898. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15626
Quoting want2lrn:


Hey Kid, could you post that model or tell me how to find it...Corpu here and want to keep ahead of the game on this one 92L, we have been lucky so far...


I assume you mean from Corpus Christy? If so, and if you have not seen it already, might be of interest to you concerning 92L. I haven't seen GFS develop it but could be wrong. Wouldn't be the first time. :) Link
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Quoting StormW:


When maximum sustained winds reach a minimum of 74 mph. J/K

Could not help a grin!
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Quoting StormW:


When maximum sustained winds reach a minimum of 74 mph. J/K


trof
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Quoting kmanislander:


I don't think so. His disciples call it that. LOL


Having trouble finding it. Got the short version by any chance.
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let me Edit my last statement. If you have a pay site you may see a completed run now.
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890. JRRP
out for now
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Quoting plywoodstatenative:
the last storm that bounced off of the Yucatan did not do so well with us...


Are you talking about Wilma? That was 5 years ago.
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888. JRRP
here in Santo Domingo is raining a lot
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Quoting doorman79:


Kman,
Is there a technical name for the John Hope rule?

Trying to google it TIA


I don't think so. His disciples call it that. LOL
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Quoting Patrap:
18z Early Cycle NHC model tracks
Invest92
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)







Dynamic Models (More sophisticated models)






LGEM? 135kts?
Member Since: August 26, 2006 Posts: 16 Comments: 4766
the last storm that bounced off of the Yucatan did not do so well with us...
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Quoting clwstmchasr:


384 hours out is a bit too far for me to get ready. Having said that, I do believe that if this season stays active October could get interesting.

Remember the Great Tampa Bay Hurricane of 1921 hit in Oct.
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882. IKE
Convection dying off with 92L....

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This run is 18 hours old and shows a scenario that may happen in two weeks. This is not 92L, 93L, or Igor.

Member Since: August 26, 2006 Posts: 16 Comments: 4766
Poll Time:
When will Igor become a hurricane?

A: Tonight

B: Tommorow Morning

C: Tommorow afternoon

D: Moday
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92L though convection has waned sure has the look of a tropical cyclone, will be a large system if it develops also. I suspect it will be blooming in the morning again.
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Quoting reedzone:
114 hours..


Second trough is strong, straight north of Igor which means Igor has to recurve soon or the ridge, which is also strong builds and steers him west.


Big weakness shown in the ridge due to the forecasted deep trough. The high that builds behind that trough would likely serve as a blocker to any further westward motion by Igor and force him to take the line of least resistance to the NW just as Earl did. The danger would be in a weaker trough, much flatter and exiting to the NE quicker. The high would then build to the North of Igor instead of to the NW and steer Igor to the WNW instead of acting as a blocking high.

It will all turn on just how strong the trough turns out to be and how far South it digs as that will determine the size and duration of the weakness in the sub tropical ridge.
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Quoting weatherportricheyfl:
has anyone seen the scary model for the gfs 384 hrs from now west coast of florida get ready


must be an old run the Last run dropped it and the new run hasnt gone that far yet
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18z Early Cycle NHC model tracks
Invest92
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)







Dynamic Models (More sophisticated models)




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Looks like the 3rd trough recurves Igor near Bermuda on the 18Z GFS.. I did say east, but I might have been wrong on that.
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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.