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 Drakoen:


TS or Hurr conditions
hey drak good to hear from you, so far florida has been spared so far
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Quoting Sfloridacat5:
Yeah, that was a scary forecast path for S.W. Florida.


And she got stronger...I was is W.Palm Beach and the eye came over us. First half was pretty bad but after Jeane and Frances...nothing we hadnt seen before. But When the back half hit.....WOW...I was surprised! By night fall as she left it was 60 degrees.
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92L will more than likely be upgraded at 5pm, my main concern will be the heavy rain on the islands it is a huge storm
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269. 7544
92 is lifting north going over pr ?
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Quoting weatherwatcher12:

Hey Drak, what effects could be felt in the Jamaica/Cayman region?


TS or Hurr conditions
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92L

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E D I T


Good morning, all.

RESPECTS remembering the 911 fallen and their families!




Igor is going to struggle with dry air just as the others have before it, keeping the system disrupted but not enough to TO NOT feel the tug of the approaching trough. 92L is in the dead zone, hardling anything spins up there - at least not quickly. It's a broad system and, like xG, will have a tough time getting wound up tight around a coc. 93L, however, looks fairly impressive early, but they all do in that position.

It's a waiting game, and I'm beginning to wonder if prevailing conditions can be too perfect? SST's too warm for development? Certainly, much has defied development odds so far, imo.
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Quoting KanKunKid:


"Explosive" is a rather subjective term and is ofter overused here on the blog when referring to growth of a weather system. For all intents and purposes, there are no "explosions" in a tropical weather system. Just because something is much bigger when we see it now, than it was an hour ago, is not an explosion. If that was the case, well, I'm not going there.
You may be somewhat accurate to refer to a rate of growth as "explosive", but it is the rate of growth, not the actual system. The "drama" and exaggeration do not help us learn or observe and study these systems. It's just annoying.


I was refering to the convection. If you see that system yesterday and you see it today, you can see an explosive convection development.
The term explosive is a subjective term, not necessarily applied to an explosion.
Why some of you want to make a soap opera of every post people made?
Maybe is time that some of you mature a little at least.
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Yeah, that was a scary forecast path for S.W. Florida.

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Quoting CaribbeanStorm:


It seems to me that we will get at least tropical storm conditions here in Jamaica by Tuesday...and that reminds me of Gustav.

That's exactly what I thought when I saw its position.
Member Since: May 16, 2009 Posts: 1 Comments: 1231
Quoting btwntx08:


hi btwntx - any models hinting at where and how strong 92L will be?
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That map by btwntx08 may just be pointing to a trough that will not allow whatever 92L becomes to get all the way to Texas....see the trough coming?

Quoting btwntx08:
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Their has been two tacks this year.tex/mex,and out to sea.Only one storm so far was the odd ball,which was bonnie.
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011L/TS/I/CX
INV/92L/XX
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Quoting weatherwatcher12:

I was afraid that that would be respose. Well I'm starting to get prepared as the Dr. says that it could start affecting us in 48 hours.


It seems to me that we will get at least tropical storm conditions here in Jamaica by Tuesday...and that reminds me of Gustav.
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Wilma wasn't projected to hit TX/MX at any time.
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Quoting Goldenblack:
I don't know if it holds water Jeff...

** I do want to note though, with the current pattern resembling more in the way of east coast to gulf coast troughs...this has a possibility of happening, though I still think the target is once again Mex/Tex..



If I remember correctly, Wilma was forecasted to cross the Yucatan, stall, and them move back towards Florida.
At the time, I was very impressed at how it turned and ended up making landfall basically where the NHC forecasted.
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249. 7544
92l looks like it shifting nw at this hour ?
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Quoting ackee:
92L WONT BE upgraded to a TD until sometime tonight or on sunday need to organized somemore


T-numbers this morning were T1.0 and T2.0. Only a slight increase would warrant classification.
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246. JRRP
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I don't know if it holds water Jeff...

** I do want to note though, with the current pattern resembling more in the way of east coast to gulf coast troughs...this has a possibility of happening, though I still think the target is once again Mex/Tex..

Quoting jonelu:


Its alittle early for that kind of pattern...but I guess anything is possible.
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Quoting luigi18:


heavy rain here in san juan!

Is going to be a day of flooding.
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Oh good so it's safe to say I can right off Igor becuase it won't affect land?.Okay.
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Quoting spathy:
Yesterday was the statistical peak of Atlantic Cane season.
Looking at the Sat pics today seems to give new meaning to the phrase"Its all downhill from here"


Suspect the season won't peak until the 25th or so.
Member Since: July 8, 2005 Posts: 259 Comments: 24574
Quoting RecordSeason:
Don't go believing everything you see on models.

Remember, Earl weren't sposed to go anywhere near PR or the east coast at about this time. Then the models and NHC track kept shifting west, west, west, till they get slammed.

Igor probably does the same thing, IMO...

I tend to agree with your opinion!!!
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239. beell
Hey, Drak,
Good time to get on the list of well-wishers as you begin your formal education.

If you can survive on the Doc's blog-you can make it anywhere.

Good Luck!

And Levi, too!
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TS Igor

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Quoting Sfloridacat5:


Jamaica "could" experience strong tropical storm or possibly hurricane conditons. I would be prepared just in case.

I was afraid that that would be respose. Well I'm starting to get prepared as the Dr. says that it could start affecting us in 48 hours.
Member Since: May 16, 2009 Posts: 1 Comments: 1231
Quoting Jeff9641:
Basically remember Wilma was supposed to hit TX or MX but stalled and veered NE. This maybe similar setup based on the latest GFS.


oh... really
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Quoting Jeff9641:
Basically remember Wilma was supposed to hit TX or MX but stalled and veered NE. This maybe similar setup based on the latest GFS.


Its alittle early for that kind of pattern...but I guess anything is possible.
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233. ackee
92L WONT BE upgraded to a TD until sometime tonight or on sunday need to organized somemore
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Quoting Stormchaser2007:
Convection already waning in the southern quadrant. We'll see what happens.




heavy rain here in san juan!
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92L winding up S of PR

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Quoting weatherwatcher12:

Hey Drak, what effects could be felt in the Jamaica/Cayman region?


Jamaica "could" experience strong tropical storm or possibly hurricane conditons. I would be prepared just in case.
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Quoting RecordSeason:



What if two cat5's hit the U.S. simultaneously, and there was a meteor and a volcano and an earthquake all at the same time?

and guess what? It could happen tomorrow!!!

Well, maybe not tomorrow, but next week...

-you forgot the "JMO"... LOL!
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I don't feel good about Igor. I'm not buying a curvature out to sea, unless I see signs of it. It would leave the EC in a threat, at this point.
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Igor is starting to wind up again.
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Quoting serialteg:


its forecast to change soon


Not good. : (

Thank you for answering.
Member Since: August 22, 2009 Posts: 0 Comments: 3167
Quoting Drakoen:


92L should travel WNW through the Caribbean approaching the Yucatan Peninsula. The NHC track on Igor looks good. 93L looks to recurve up into the subtropical Atlantic.

Hey Drak, what effects could be felt in the Jamaica/Cayman region?
Member Since: May 16, 2009 Posts: 1 Comments: 1231

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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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