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 SomeRandomTexan:
kind of eery how there seems to be a shield around the US this year


Actually, kind of nice if you ask me.
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RecordSeason i am going to call a truth. Lets put all the politics aside and talk about the tropics!
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All NOAA Tropical Floater Imagery
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Happy Birthday Dr. Masters!
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Quoting StormW:


Happy Birthday to your hubby!


Thank you, I will relay the message when I get home from work.


He took today off work.. so he is at a local sports bar right now with the neighborhood "guys" all doing what men do at sports bars! ROFL!!!

shooting pool, ordering buckets of beer, watching sports, etc...
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92L Rainbow Image



RGB



WV


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Quoting jacechase:


Im going to be attending a diff school, and are kinda checking for schools, i started at ulm monroe in La, but am looking to travel out of my state for school, I was thinking FSU. Is is one of the best for Met?



Yeah FSU is one of the best for MET, and is the best if you ask me, but I'm sure some would argue with me on it being the best :)

But it is at least near the top!
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Quoting RecordSeason:
Now see here folks.

Igor looks to be drifting slightly south of west again, not that this surprises me.

Cone will shift west, west, west, west...

...as anticipated...

RecordSeason, did you notice, on the Central Atlantic Visible Loop, some sort of spin at 30N 50W? If so, what is it?
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Igor is going out to sea.Have heard no one say it is threat to US.
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562. BlxMS
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...Camille, Frederick, Elena, and Katrina

2)After Camille, your darned right. They ceased to be "fun and exciting". Camille was physically the most frightening (but I was only 13)but Katrina was the most discouraging. For months, we just wondered if life would ever be the same...btw, its not yet.

3)Katrina softened my hard head. I will not stay in the bullseye of another major. Insurance replaces "stuff", but not human (or pet) lives.
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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)






The simple graph really leaves the whole Gulf coast open for a hit. Scary.
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Quoting AtHomeInTX:


I'm a complete amateur in the weather department but I find it fascinating as well. And you are correct. Admitting you could be wrong is key to any science. I have seen so many shows, read so many things by scientist in all genres who are absolute that they are correct. Every time I hear/read this I am so glad for all the scientist who have admitted they were wrong so science can progress. That kind of works in life in general to. Sometimes you have to admit you're wrong and move on. If you can't laugh at yourself life can seem really, really long. Lol. Well I learned something else from you today. I thought the pwats dealt with rain but never connected it to tropics. DUH! it takes me longer than some to catch on. Lol. Good luck with your met degree. You're starting off on the right foot. :)



Yeah thanks!

As human beings, no matter how how much experience or school we have, we will have flaws, and will make mistakes.

Its sad because I have seen experts who will be wrong more often than they should just because of arrogance, you learn more, and become better at what you do if you stay humble, but arrogance drives you farther and farther from the truth if you let it take over.


We all struggle with pride and arrogance, not wanting to admit we are wrong, but its when it takes over are lives, that's when its a problem.



The thing is, people sometimes start out humble, than when they get their degree or experience they get arrogant, then they aren't so reliable anymore, which drives them farther from the truth.


The key is staying humble, and always ready to learn more from others, as well as admit our own mistakes.
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Watching Igor up here in Nova Scotia, Canada....we handled Earl fairly well, we were prepared!

Wondering if Igor will be taking the same track as Earl??
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Quoting MiamiHurricanes09:
I agree there, right now the circulation is in the mid-levels. Once it translates to the surface, a hurricane is very possible.


It probably has the best "upper exhaust" pattern of any incipient TD this season. This is why the global dynamical models; esp CMC which usually goes overboard, are perplexingly weak with its development. I've looked that the analysis and there is very little in the way of surface data and only 1 radiosonde site nearby. Sat-obs are at their least dense at low lattitudes.

The other factor are in the internal dynamics. here's a hint:Link

This is a 48 hr proabilistic QFF forecast from NAEFS. There is a max in the 92L area, but the std deviation is very high. So some ensemble members generate adequate convection to concentrate vorticity, and in others convection is supressed (due maybe to the strong ridge at mid-upr levels) which probably explains the consensus lack of enthusiasm for storm formation.

Its still an oft mystifying thing.
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Dr Master's BD is today? It is also my husband's birthday... Sept 11th.


so Happy Happy Birthday to you Dr Master's
and thank you for providing this community we all love so much!

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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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Quoting Jedkins01:


Florida State


Im going to be attending a diff school, and are kinda checking for schools, i started at ulm monroe in La, but am looking to travel out of my state for school, I was thinking FSU. Is is one of the best for Met?
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Quoting scott39:
Its funny to see how people think because there has been a common steering pattern with the TCs this season, that all of them are going to keep going to those same places!!!! MEXICO---FISH!!! Thats insanity!! LOL
Insanity was harsh girls and guys. confused would be a better word. Sorry
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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. I'm a weather nerd so I must admit I have.
I'd be lying to state otherwise.

2.Yes, I learned, while you will have damage, sometimes more, sometimes less, you know in your heart, if you are really prepared and your home is secure and you have done all your "prep work" you can survive the storm. This is only if you are not in an evacuation area or an insecure home (will not stand up to a storm) .If you are suppose to get out.. then "GET OUT" And if you are not afraid of getting hurt because you are prepared, you can watch Mother Nature at her most furious. I do truly understand those that chase these storms.


3. Yes. Because we had 7 days without electricity after Wilma, (many other family 14 days) I got to experience "long term" without power ....
more than just a day or two like previous storms... so now I have a better idea of what supplies my family needs the most and which ones we really did not use at all.


good question...
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Quoting beell:


1. Yes
2. Yes.
3. Pants


LOL - ain't that the truth! ;)
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Quoting seflagamma:


Hi Jed,

So happy you are going to FSU, so many of our young here went to Met School there. I know you love Meteorology and will be so successful.

It has been so much fun watching all of you "kids" from 5 years ago become "young adult" students of weather!

and I see we now have a new young crop of "kids" on here with aspirations and great talent!

Gamma



haha thanks! it is funny isn't it? Also considering I don't have any friends in my home area the same feel for weather, I sometimes think I'm the only one that loves weather so much. But then I find out its a big world and there are more of "me" out there lol
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546. BlxMS
STORM...W/o sounding like I'm secretly in love with you, I totally repsect your skills and input on all things tropical, but I'm still learning. A bit of a tech ?? for you. On the 240 hour Euro, it looks like Igo, after the recurvem is completely imbedded in some high prseeure milibars..on all sides. I seem to see that the controlling ridge does break down some from the SW at the point of recurve, but Igor seems still to pierce a 1018 isobar lying to its north. What determines how "much" of a weakness is necessary to pull (or allow for a recurve)a TC north??? Is it a raw pressure number? Or, does the pressure gradient between the weakening ridge and the TC have anything to do with a storms ability to "pierce". Also, can you give me a short description of what I've seen our here as an "omega block"? Many thanks for all your fine work and communicatios.
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545. MZT
Got a nice, gentle rain today in N.C. from what was left of Hermine. Sometimes I can still sense the "tropicalness" of the leftovers (such as with Ivan) b/c they are unusually breezy. But it looks like Hermine merged into the trough pretty thoroughly. Just feels like a usual, cool Great Lakes low.
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Also funny how everyone says pattern change next week and pattern does not change!Models have proved worthless,pattern change for 6 weeks now. Nada!
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Please feel free to wish Dr. Masters a Happy Birthday here or on his FACEBOOK page
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E D I T

Quoting MiamiHurricanes09:
There goes the convection. Considering it doesn't even have a surface circulation, I'd put the chances near 30%, rather than 60%.


Exactly. We watched this with xG - same deal.


And, on the wv/dry air discussion, dry air can indeed be found at various levels in the atmosphere. But, there is no wv imagery (tmk) that reflects wv solely at the sfc. CIMSS does have imagery that depicts both, mid and upper, level wv. However, the GOES wv imagery is simply an "overall" non-static depiction of wv/dry air of all layers.

And, we all know about evaporation, no stretch there - the lower levels will usually have some moisture content depending on winds, currents and general radiance on sfc temperatures. As moisture rises it can also be more dispersed at the mid and upper levels - that too, depending on winds, developing patterns, etc.

The tropical cyclone engine only works when there is constant, regenerative moist air circulating through a flue of rising and then sinking (convergence and divegence) moist air, being heated then cooled as it rises. Dry air at any level can disrupt this moisture-moving process, but apt to be more significant, especially in cyclogenesis, at the mid and lower levels. As cyclogenesis matures, moisture self-containment occurs unless it loses its fuel source, there is dry air infiltration, or there is destructive winds over a system that keep the process from becoming regenerative and fully maturing.
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Quoting Jedkins01:



No problem, weather is a very complex science! But I love it, it helps keep you humble, as long as you are willing to admit you are wrong, seems like the weather is always a step ahead of even the smartest of experts, and I'm not exactly the smartest of experts! lol

I'm just staring my MET degree towards FSU, it has me all the more pumped about weather!


I'm a complete amateur in the weather department but I find it fascinating as well. And you are correct. Admitting you could be wrong is key to any science. I have seen so many shows, read so many things by scientist in all genres who are absolute that they are correct. Every time I hear/read this I am so glad for all the scientist who have admitted they were wrong so science can progress. That kind of works in life in general to. Sometimes you have to admit you're wrong and move on. If you can't laugh at yourself life can seem really, really long. Lol. Well I learned something else from you today. I thought the pwats dealt with rain but never connected it to tropics. DUH! it takes me longer than some to catch on. Lol. Good luck with your met degree. You're starting off on the right foot. :)
Member Since: August 24, 2010 Posts: 0 Comments: 253
Quoting jacechase:

which college are you currently attending? jedkins


Florida State
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This season is not like 2008 troughs taking storms out to sea and high pressure sends everything into mexico.
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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. Experienced big one (Andrew), and whole bunch of smaller ones including Katrina, Rita, and Wilma.

2. Before Andrew had never been in a hurricane, had no basis.

3. To always be prepared, even if people laugh at you. Much better to be the one sitting with no worries, than saying omg.
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Its funny to see how people think because there has been a common steering pattern with the TCs this season, that all of them are going to keep going to those same places!!!! MEXICO---FISH!!! Thats insanity!! LOL
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Quoting thewindman:
Just like I said before. After Sept 1st troughs get larger and further south. Hurricanes and storms will always get deflected off the coast. No reason to worry it is not July or August guys


I usually don't respond to such things--in fact, I doubt few are listening to you at all--but saying something so unscientific and potentially dangerous shouldn't go unanswered. So, allow me to state this in unambiguous terms: it is absolutely not true that after September begins, tropical cyclones will always get deflected away from and off the coast. Where did you pick up that piece of "wisdom", anyway?
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Quoting IKE:
lennit...I will agree, it's been stuck in the same pattern all season...

(1)Northern islands and points NNW through NNE of there.
(2)Western Caribbean crossing the Yucatan...heading toward Mexico and lower Texas.

Bonnie?
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Quoting thewindman:
Just like I said before. After Sept 1st troughs get larger and further south. Hurricanes and storms will always get deflected off the coast. No reason to worry it is not July or August guys

I have a three-letter answer for you: IKE.
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30N 50W I think I see something in the Central Atlantic Visible.
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Welcome to da 50's club Dr. Masters.

And another 50 good years to come for ya too.

Happy B-day.


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Quoting StormW:
Levi,
Fantastic update!

You see now the models I was talking?
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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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