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 AtHomeInTX:


I think she was the strongest ever in the gulf pressure wise. Or I could be wrong. :)
The 1935 Labor Day Storm(technically)probably holds that record. I Dunno.
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Wow,
This storm 92L looks like its becoming Julia,
the outflow is looking alot better, and just
looks to be strengthening to me, hmmm now where is it going???????????????????????????
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Quoting IKE:


92L has had a rough day....



Good! :)
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Quoting RufusBaker:
92 is retarded the carribean is HOT it the peak of the season but yet it is fizzing like a egg on hot pavement




Sounds GREAT to me !!!! In a Austin Powers voice, "YEAH BABY YEAH"
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Quoting AtHomeInTX:


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


Sorry, stepped away for a sec. Yes i do mean Corpus Christi, i don't know much but i do know that this setup that has TC's going into Mexico is enough to keep a crooked eye on them. Doesn't take but a "wobble" to the north and we are in the bad side of one of these. P.S. Thanks to those of you who are patient enough to answer my questions! i.e stormw,kman,kid,btwntx,will and any others that i may have missed.
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Quoting kmanislander:
850 vort no better in this updated image. 92L is probably at least 24 hours away from becoming a TD at the soonest IMO.



Very good to hear that for us playing the watching game in it's target lines, and I agree.
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Quoting jason2010xxxx:
TROPICAL STORM IGOR big fish storm
Quoting washingtonian115:
For the love of god,please stop protesting.We get our point.

The "ignore user" button is a wonderful thing. You should try it out on Jason. I did and it has improved my WU experience 100x!
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You guys know that this year has a lot of the same names as the 2004 season did!
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Igor is likely a hurricane at 11PM

93L is likely at 60%-70% at 8PM, and a TD/TS tomorrow.

92L is confusing me.
Member Since: July 6, 2010 Posts: 113 Comments: 32262
960. IKE
Quoting AtHomeInTX:


Hmmm? Not strong on 92L. But farther north than I've been seeing with some models.


92L has had a rough day....

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Quoting clwstmchasr:


Is a slight trend west a significant change in the 18Z model run?
As it turns out, the run is complete and I see no significant change, at least in Igor track. Please, enlighten me.
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Quoting jrweatherman:
Looks like the threat to us here in Florida will be later in the month and October which is basically right on target with climatology.


Lets see what happens.....

I'll be very surprised if S.E. Florida does not get anything this year
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Quoting will40:


no fish on GFS 18Z

About which one????
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Quoting IKE:
18Z NOGAPS...Link


Hmmm? Not strong on 92L. But farther north than I've been seeing with some models.
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we still might get a TD out of 92L at 11pm when D-Max should start to kick in or at 5am
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Wow how is it that 92L fizzled like that in the peak of the season?
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stormpetrol

Not a problem. Thanks for the response now.
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Quoting kmanislander:
850 vort no better in this updated image. 92L is probably at least 24 hours away from becoming a TD at the soonest IMO.

Now I know why people from the Caymans always mention IVAN,,,,,..................................................After passing Jamaica, Ivan resumed a more northerly track and regained Category 5 strength. Ivan's strength continued to fluctuate as it moved west on September 11, and the storm attained its highest winds of 165 mph (270 km/h) as it passed within 30 miles (48 km) of Grand Cayman. Ivan reached its peak strength with a minimum central pressure of 910 mbar (hPa) on September 12, making Ivan the tenth most intense Atlantic hurricane on record, as of August 2007. Ivan passed through the Yucatán Channel late on September 13 while its eyewall affected the westernmost tip of Cuba. Once over the Gulf of Mexico, it weakened slightly to Category 4 strength, which it maintained while approaching the Gulf Coast of the United States.[1]
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950. IKE
18Z NOGAPS...Link
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Taking a break now.
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Quoting TexasHurricane:


just watched it. Thanks.... :) Just need to keep an eye on the high. You would think it would break down sooner or later....


Lets just hope it holds strong when it needs to. A breakdown come about November would be nice. :) Not that's wishcasting folks! Lol.
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Kman,

Makes sense. Thanks
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946. IKE
933...no...it's not over. Personally...I'm encouraged by what I see for my area. I always looked at the date Opal hit here as kind of a point where the odds start falling off. That date was Oct. 4th.
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850 vort no better in this updated image. 92L is probably at least 24 hours away from becoming a TD at the soonest IMO.

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Quoting Cat5Survivor:
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

I was just reading back , been away for awhile and saw you directed the question to me, sorry I can't answer as I'm not as familiar with the various charts and graphs but if anyone can answer your question you have directed it to the right person now, Kman, if anyone can explain it to you he will in simple and understandable terms, sorry I couldn't be of any help.
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Quoting hurricanehunter27:
THE best looking hurricane in the gulf ever!
Link


I think she was the strongest ever in the gulf pressure wise. Or I could be wrong. :)
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UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 11 SEP 2010 Time : 214500 UTC
Lat : 17:24:15 N Lon : 41:24:08 W


CI# /Pressure/ Vmax
4.3 / 982.2mb/ 72.2kt


Final T# Adj T# Raw T#
4.3 4.3 3.1

Latitude bias adjustment to MSLP : +0.0mb

Center Temp : -46.7C Cloud Region Temp : -58.7C

Scene Type : UNIFORM CDO CLOUD REGION w/ MW EYE

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : ATLANTIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : MW ON
Weakening Flag : OFF
Rapid Dissipation Flag : OFF
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Quoting AtHomeInTX:


Hey Tex! Lol. Yeah, gots millions of 'em. Including my nervous smile when talking about my comfy home. Don't want Mother Nature to think I'm getting cocky and need to move again. Lol. Did you see the video I linked from Lake Charles NWS? It explains a lot. Link


just watched it. Thanks.... :) Just need to keep an eye on the high. You would think it would break down sooner or later....
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Quoting clwstmchasr:


I was only 1 year old so I don't remember it.


How old are you??????
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THE best looking hurricane in the gulf ever!
Link
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Quoting Tazmanian:
902. galvestonhurricane 3:33 PM PDT on September 11, 2010 Hide this comment.
RIP 92L
Action: Quote | Ignore User


POOF


lol
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Looks like the threat to us here in Florida will be later in the month and October which is basically right on target with climatology.
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I really thought 92L would be a depression today. Wrong again!

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Quoting Cat5Survivor:
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


Hi, I looked at your post. Without all the technical comparisons that would be required, it is easiest to appreciate that models have a very hard time with intensity forecasts before a system gets classified as a TD. The intensity spread can be very large and you may have seen several waves developed as powerful hurricanes this year by the models but they did not even go on to become TDs.

My rule of thumb is to ignore intensity forecasts until we have a classified tropical cyclone.
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Quoting wunderkidcayman:
galvestonhurricane you must ha gone mad dead 92L is nowhere near that


I don't understand why the models aren't calling for much out of 92L when conditions seem favorable. I know models are just models but they do make me frustrated some times when they show such different outcomes. No patience I guess. Lol.
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Ike you think season is over?
Member Since: September 18, 2006 Posts: 0 Comments: 1282
Quoting clwstmchasr:


I was only 1 year old so I don't remember it.

Do your parents recall what happened that day?
Was it really bad?
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no fish on GFS 18Z
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Quoting reedzone:
The second trough is stronger on the new run, this would really strengthen the ridge to the west.
The run is nearly complete and I don't see any major change in the gfs track for Igor. So, my guess (moving further west, was wrong, "I get nothing, I lose, good day sir")
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Quoting cyclonekid:
Oh. Ok. Thanks. So one storm that kind of contradicts that is Hurricane Omar 2008?



Omar was an October storm that had its genesis on the tail end of a cold front, not an easterly wave like 92L. Remember I said that half of the 8 or 9 I found to have formed in the eastern Caribbean were late season systems from cold fronts.
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Quoting TexasHurricane:



lol.... :) all those different faces.


Hey Tex! Lol. Yeah, gots millions of 'em. Including my nervous smile when talking about my comfy home. Don't want Mother Nature to think I'm getting cocky and need to move again. Lol. Did you see the video I linked from Lake Charles NWS? It explains a lot. Link
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Quoting cyclonekid:
What's the John Hope rule?


He said if a storm doesn't develope by the time it reaches the eastern carribean, it won't until it reaches the western carribean. He was a NHC forecaster, IIRC.
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926. IKE
GFs takes Igor to near Bermuda and then toward Newfoundland. Has 93L head to the north ATL. Does little to nothing with 92L. Shows nothing after Igor and 93L are gone.
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Quoting IKE:
The center of 92l looks to be 15 degrees north-67.2 west.
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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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