92L still a threat to develop; Igor a hurricane; TD 12 forming near Africa

By: Dr. Jeff Masters , 2:18 PM GMT on September 12, 2010

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Tropical disturbance (92L) over the Central Caribbean, a few hundred miles south of the Dominican Republic, remains a threat to develop into a tropical depression. Satellite loops this morning show 92L may be starting to form a surface circulation, and an Air Force Hurricane Hunter aircraft will investigate 92L this afternoon to see if a tropical depression is forming.

The storm has only a modest area of heavy thunderstorm with limited low-level spiral banding and upper-level outflow, thanks to an infusion of dry air last night that disrupted the storm. Long range radar out of Puerto Rico shows that heavy rains are affecting that island, but there is no rotation to the radar echoes evident. Wind shear over 92L is low, 5 - 10 knots. The waters beneath are hot, 29.5°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 to west-northwest at 15 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 Belize or Mexico's Yucatan Peninsula on Wednesday. On this track, the southern Dominican Republic can expect heavy rains of 3 - 6 inches today through Monday morning; southern Haiti can expect similar rains tonight through Monday night, and Jamaica and the Cayman Islands can expect heavier rains of 4 - 8 inches Monday and Tuesday. Eastern Cuba can expect rains in the 2 - 4 inch range. Once 92L crosses the Yucatan, the ridge of high pressure steering it is expected to remain in place, forcing 92L to a second landfall in Mexico south of the Texas border.

Intensity forecast for 92L
NHC is putting the odds of 92L developing into a tropical depression by Tuesday at 50%; I'd put them higher, at 70%. However, time is running out for 92L to become a hurricane before hitting the Yucatan Peninsula on Wednesday. Given the current disorganized state of 92L, it would be difficult for it to intensify quickly enough to become a hurricane by then. The storm may also suffer another of its mysterious evening collapses, where it loses most of its heavy thunderstorm activity. However, the SHIPS model predicts wind shear will remain low, 5 - 10 knots, through the period, and 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. There are a number of research flights being made into 92L this afternoon that should help long-term efforts to make better predictions in the future on whether or not disturbances like this will develop or not.


Figure 2. Morning satellite image of Igor.

Igor
Hurricane Igor appears destined to become a large and powerful major hurricane over the Central Atlantic in the days to come. Wind shear is low, 5 - 10 knots, and is expected to drop below 5 knots for the next five days. Waters are warm, 28°C, and will warm to 29°C by Wednesday. Igor has moistened its environment enough to keep the dry air of the Saharan Air Layer (SAL) at bay. Igor is undergoing a period of rapid intensification today, and will probably be a Category 3 or 4 hurricane by Monday.

The track forecast for Igor remains unchanged. Igor will move west under the influence of a strong ridge of high pressure for the next 2 - 3 days, then turn more to the west-northwest then 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 does have a small chance of making landfall on the U.S. East Coast or Canada. Climatology shows that about 15% 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 10% for Canada. The forecast steering pattern for the period 5 - 12 days from now from the ECMWF and GFS models 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. Recent runs of the ECMWF model indicate that these troughs may not be as intense as previously thought, so it is possible Igor has a higher chance than usual to hit land than climatology suggests. One wild card may be the possible development of TD 12 behind Igor. If TD 12 develops into a hurricane, and moves close to Igor, as some of the models are suggesting, the two hurricanes could rotate around a common center, forcing Igor more towards the coast of the U.S. The long term fate of Igor is difficult to predict at this point.

Tropical Depression Twelve forms
Tropical Depression Twelve formed between the Cape Verdes Islands and coast of Africa this morning, and is already affecting the Cape Verdes with winds near tropical storm strength; sustained winds of 35 mph were recorded in the northwest Cape Verdes this morning. You can follow the progress of TD 12 through the Cape Verdes today using our wundermap.

Next post
I'll have a new post Monday morning, and perhaps late this afternoon if events warrant.

Jeff Masters

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3646. Ryuujin
Thanks, but that was quite a few years ago now. To be honest, it was just all of a sudden and poof. It was only about 3 miles from where my sister lived. Crazy stuff.
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3645. xcool


cmc on now too

PGI45L
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3644. JP2010
Quoting PSLFLCaneVet:
An amateur, but an avid one. I have an L-series. Mine is the 24-105 IS. Great walking around lens with excellent short to medium focus. Sounds like you're looking for a telephoto at medium to long range. Depends on what you're looking to shoot.


This is the best lens i have ever used a lot storm photos. This lens is not 70-200 L is great lens high recommend it.
Member Since: August 1, 2010 Posts: 0 Comments: 18
Quoting Ryuujin:
Man I really feel for you guys on the coasts. We get the random out of the blue thunderstorms here in the midwest. Last bad one we had was in November, EF3 tornado at 3am. Killed 23 people, including a friend of mine from High School.
Thanks for the sentiment. I am sorry for your loss.
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3642. xcool
F4PHANTOM ."I Remember That"
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Quoting F4PHANTOM:
Maybe not 92L. Could be something following 92L


Nope thats 92L Link
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3638. xcool
txsweetpea :))))
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Quoting xcool:
txsweetpea i'm from new orleans now stay in slidell la.....

Oh ok ...I didnt know you were that close to my area.
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3636. xcool
txsweetpea i'm from new orleans now stay in slidell la.....
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3635. xcool
maker 3 time gfs shows PGI45L in gom .i'm not 100% sure...
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Quoting Ryuujin:
Man I really feel for you guys on the coasts. We get the random out of the blue thunderstorms here in the midwest. Last bad one we had was in November, EF3 tornado at 3am. Killed 23 people, including a friend of mine from High School.


Tornadoes are awful too. I'm sorry about your friend. :(
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Quoting xcool:
so getting ready for homeee grown storms.

hello xcool where are you from?
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3632. xcool
AtHomeInTX yep.
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2010SEP13 021500 6.8 928.6/ +2.0 /134.8 6.7 6.6 6.6 NO LIMIT ON OFF 15.04 -68.88 EYE 22 IR 17.60 47.61 COMBO
2010SEP13 024500 6.8 928.6/ +2.0 /134.8 6.6 6.5 6.5 NO LIMIT ON OFF 15.84 -67.93 EYE 21 IR 17.55 47.64 COMBO
2010SEP13 031500 6.8 928.6/ +2.0 /134.8 6.5 6.4 6.4 NO LIMIT ON OFF 15.24 -66.88 EYE 21 IR 17.55 47.80 COMBO
2010SEP13 034500 6.8 928.6/ +2.0 /134.8 6.5 6.4 6.4 NO LIMIT ON OFF 15.94 -66.55 EYE 20 IR 17.56 47.90 COMBO
2010SEP13 044500 6.8 928.6/ +2.0 /134.8 6.4 6.4 6.4 NO LIMIT ON FLG 12.64 -67.16 EYE 21 IR 17.58 48.00 COMBO

Eye cooled 3.3 degrees in the last 1/2 hour. Either a contaminated read or an EWRC? Outflow was a little constrained in the NW, but looking better now.
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Quoting xcool:


PGI45L ^^^^^^^^ ....

here pics




OH! THAT'S what that is? It looks mean already.
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of course it's the gfs & lala land! LOL...gfs just now jumping on board with a reflection of 92L
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3627. xcool
CoopNTexas not yet .soon
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3626. Ryuujin
Man I really feel for you guys on the coasts. We get the random out of the blue thunderstorms here in the midwest. Last bad one we had was in November, EF3 tornado at 3am. Killed 23 people, including a friend of mine from High School.
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3625. JRRP
see you tomorrow
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Quoting Vapors:


Same here, I really don't feel like rebuilding my home again. I just recently won my lawsuit against TWIA from Ike...


Ouch! Sorry about your home. Lost mine in Rita. Didn't get rebuilt but it's all good now. Better neighborhood. :) But it didn't get all better easily or quickly. Nothing I want to repeat as long as I live. Fingers are crossed for no more.
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gfs suggests that cvs season not over yet. keeps developing a wave, which is PGI45L.

Developed it the last several runs. ends in GOM

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3622. xcool


PGI45L ^^^^^^^^ ....

here pics


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Quoting xcool:
F4PHANTOM put usa at highrisk .


Yes!!
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3618. Ryuujin
Wow Orca, nogaps is starting to get really scary.
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3617. xcool
so getting ready for homeee grown storms.
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Africa in colo & motion link

Link

Quoting winter123:

Wow. Name that blob right now!
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3613. xcool
F4PHANTOM put usa at highrisk .
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Quoting F4PHANTOM:
Then we can direct our attention to the fronts that stall in the GOM or Carib. for mischief.


I just said that too. :)
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Quoting xcool:
AtHomeInTX .yeah.cv season come to end soon


Yeah home grown will have us on the edge after that.
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Quoting sunlinepr:
Beautiful Africa...


Wow. Name that blob right now!
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3609. Vapors
Quoting AtHomeInTX:


Ok. Thanks. Hadn't read that one yet. Hope it does hold firm. :)


Same here, I really don't feel like rebuilding my home again. I just recently won my lawsuit against TWIA from Ike...
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CMC 92l stronger into NE MEX Sunday. Seems to stall for days in GOM. Link
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Quoting F4PHANTOM:
Did they give a location?


Yes, they were in D.C.
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Looks like I got back just in time from the Golf Tourney... its going to start hopping :)



AOI

AOI

AOI

AOI

AOI

TS BUSTED FORECAST ALIBI
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Quoting TXEER:


Thanks...and great points...I just wish I had a "Who's Who in the Zoo" so I could know who to pay attention to..as opposed to who is blownwg smoke and wish casting!


Well, for starters, I'd pay attention to some of the posters who have mini-blogs. Read up on their blogs and check out their blog page. Usually, if they have some credible expertise, they will let you know what it is on their page. Also, watch for regulars on the board that many respect. Chances are, those posters already have let their expertise be known among those that follow them and you can usually trust their opinions. It takes a little getting used to, but its usually not too hard to find the "good eggs". Just pop on at different times of the day and you'll find them.
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3602. xcool
AtHomeInTX .yeah.cv season come to end soon
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Quoting AtHomeInTX:
the next weekend storm some were mentioning? I know, I know its a long ways off. :)


Wow!!!
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Feed us Africa...

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Quoting pcola57:
RE post 3570
Well spoken..IMO


African Continent Very Robust
Agreed. It appears my +10 post to drako19 was eaten. Now I feel obligated to double that to +20. LOL
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3597. Ryuujin
Quoting dracko19:


Indeed. All 3 models show IGOR moving North at some point...but to a point. The GFS is showing a weakness between the two ridges, but then the ridges filling in...albeit not as strong as the NOGAPS. The NOGAPS on the 00z run shows IGOR turning back to the West after it gets to around 27N. My point was why? Why did it shift? The ridge looks like the answer. Have a look:



Don't forget GFS has a cold bias that always overplays the strength of trofs as well.
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3596. leo305
Igor's been moving south of due west since yesterday..
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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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