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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Quoting RecordSeason:
2878:

Nah, based on microwave and Shortwave IR, Igor isn't even close to thinking about IWRC...


So now the hurricane sends you private messages and last message from Igor said, "yeah, ima wait, i don't feel like shutting my eye right now, i'll let you know when I plan on doing so."
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Wow, just don't see the trough influencing steering at this time, maybe the second trough, but I am now seeing what StormW was talking about.

Member Since: Posts: Comments:
ZCZC MIATWOAT ALL
TTAA00 KNHC DDHHMM
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT SUN JUN 13 2010

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

1. A LARGE LOW PRESSURE SYSTEM LOCATED ABOUT 975 MILES WEST-SOUTHWEST
OF THE CAPE VERDE ISLANDS IS PRODUCING WIDESPREAD CLOUDINESS ALONG
WITH SOME SHOWERS AND THUNDERSTORMS. THIS DISTURBANCE CONTINUES TO
BE WELL-ORGANIZED AND ENVIRONMENTAL CONDITIONS ARE EXPECTED TO
REMAIN CONDUCIVE FOR ADDITIONAL DEVELOPMENT OF THIS SYSTEM AS IT
MOVES WEST-NORTHWESTWARD OR NORTHWESTWARD AT 10 TO 15 MPH. THERE IS
A HIGH CHANCE...60 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER STEWART/BLAKE
NNNN

Remember this pain in the butt...got bored...
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Quoting KATRINABILOXIGIRL:
By the grace of God hun! So far so good. Just need to keep on hanging in there and pray for the best!

Absolutely. I hope this pattern hold out. I hope that no one is affected by Igor, or any other storms for the remaining season.
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folks...quit whining on whether this is this or that. get a little bit more scientific, and little less whiney. I get tired and weary of the stupid rif raf over nothing. let's analyze this hurricane...do our job. check it out....learn stuff. put your pride in the bucket. none of your are experts...save a few....



from flhurricane.com

"An annular hurricane is a tropical cyclone in the Atlantic or Eastern Pacific Oceans that features a large, symmetric eye surrounded by a thick ring of intense convection. This type of storm is not prone to the fluctuations in intensity associated with eyewall replacement cycles, unlike typical intense tropical cyclones. Annular hurricanes also tend to persist, even when encountering environmental conditions which easily dissipate most other hurricanes. Forecasters have difficulty predicting the behavior of annular hurricanes; they are a recently recognized phenomenon, and as such, little is known about their tendencies. Because of this, they can be more dangerous than typical hurricanes."
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Although barley, 60W and south of 20N is STILL in the NHC's 5p m cone.

LINK
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If I hafta see one more pic of Julia...i swear i'm gonna puke here..... :0
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Quoting GeoffreyWPB:


The models seem to be getting confused with how the ridge and trough will affect Igor..which makes the forecast after 48 hours highly uncertain. Also the models didn't forecast or see this huge period of rapid intensification occuring, however im out of here, been a long day need to get some sleep. I really do hope that dive southward is ONLY a wobble. I'll be on tomorrow, Goodnight all.
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Quoting FLDART1:

LOL stand outside in it... I bet you cant tell the difference...


LMFAO!!
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Quoting JupiterFL:


No big deal. Sorry that 25 people had to pump their ego's by correcting you in a manner better suited for garbage. We all make mistakes.


Thank you. :)
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Quoting pottery:

Ah! The Calm, In-Control Captain....
Freaking -out within.
I know the feeling...


No Fun....glad to laugh about it now though!!
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2883. FLDART1
Quoting ElConando:


A Cat 5 is 156mph and over. 150 is a high end Cat 4. Still impressive none the less.

LOL stand outside in it... I bet you cant tell the difference...
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Member Since: August 23, 2008 Posts: 0 Comments: 1918
Quoting nyhurricaneboy:
Guys, I know that I had a temporary mind lapse. I know what a Cat 5 is. I know that 130 kts = Cat 4. I forgot.


No big deal. Sorry that 25 people had to pump their ego's by correcting you in a manner better suited for garbage. We all make mistakes.
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Quoting hurricanehunter27:
Sorry about the pre comment got a little excited by looking at sat pic!
Is Igor winking?
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Quoting MiamiHurricanes09:
Nah, dry air is distanced from the core. Just a convective fluctuation I guess.


An EWRC is also another possibility for why the convection is warming.
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Sorry about the pre comment got a little excited by looking at sat pic!
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2876. pottery
Quoting traumaboyy:


LOL....I had three buddies with me then and that was like 7 years ago and when we get together they all still swear I was trying to kill them......lol....and that I acted like I wasn't even scared........I should have received an Emmy award.....I WAS PETRAFIED!!

Ah! The Calm, In-Control Captain....
Freaking -out within.
I know the feeling...
Member Since: October 24, 2005 Posts: 0 Comments: 24382
Good night.

Should be interesting to see what happens tomorrow.
Member Since: August 9, 2009 Posts: 10 Comments: 5026
Warming cloud tops, shall see if this is temp.
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Member Since: Posts: Comments:
Guys, I know that I had a temporary mind lapse. I know what a Cat 5 is. I know that 130 kts = Cat 4. I forgot.
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Igor and friends
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Quoting GainesvilleGator:
My brother left on Saturday for a cruise to Puerto Rico. I don't know when the ship is supposed to doc. Igor will be close enough to PR to bring some big waves though. I am thinking in the 10-15 ft range so you might end up with a lot of sea-sic passengers.
Cruise ships have stabilizers and will also divert if necessary to avoid any potential rough stuff. The Redskins score!!!. Sorry...Back...you can also follow the ship at sea through their website.
Member Since: August 3, 2005 Posts: 10 Comments: 5606
Quoting Goldenblack:
A little dry air perhaps MH09?


Nah, dry air is distanced from the core. Just a convective fluctuation I guess.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting MiamiHurricanes09:
2851. nyhurricaneboy 9:48 PM EDT on September 12, 2010

That isn't category 5 intensity...that isn't the actual estimate either. It's at T6.8...which indicates winds of 155mph.

2010SEP13 011500 6.8 928.6/ +2.0 /134.8


I am aware.

My source hasn't been updated, I guess.

We're close, though.
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Quoting Hurricanes101:


would be nice if people did not post incorrect information, 130 knots is not a CAT 5
Whats a few knots between blogs?...Besides he will be at 5 shortly? right?
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We are witnessing the most powerful hurricane of the 2010 season right now and it might make it into the top ten strongest hurricanes if it keeps this up. After a day or two Igor will start to expand and beacome a good bit larger than it is now. Man, the IR sat is shows the best looken eye iv seen sence Rita in 05. I wish the 11pm advisory was 10 pm so we can see how strong it is right now! I put Igor at 90% chance at being at cat 5 satus by 11pm the only thing that could happen to stop this is EWR. Winds right now i am guessing are in the 165-175 range.
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IGOR's track is very similar to Hurricane LUIS at this point
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Quoting Hurricanes101:


would be nice if people did not post incorrect information, 130 knots is not a CAT 5


A Cat 5 is 156mph and over. 150 is a high end Cat 4. Still impressive none the less.
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A little dry air perhaps MH09?


Quoting MiamiHurricanes09:
Cloud tops are warming slightly along the SW semicircle.

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2851. nyhurricaneboy 9:48 PM EDT on September 12, 2010

That isn't category 5 intensity...that isn't the actual estimate either. It's at T6.8...which indicates winds of 155mph.

2010SEP13 011500 6.8 928.6/ +2.0 /134.8
Member Since: September 2, 2009 Posts: 130 Comments: 21194
2860. xcool


Water Vapor
Member Since: September 26, 2009 Posts: 2 Comments: 15684
2859. pottery
Quoting RecordSeason:
2833:

I was in an 18ft skiff on Lake Ponchartrain in a severe thunderstorm when I was about 10 years old. Was not an experience I'd like to repeat.

Dont blame you.
3 fishermen were killed here last year from lightening (2 seperate incidents).
Best to get out of the boat and paddle till it goes over, I think...
Member Since: October 24, 2005 Posts: 0 Comments: 24382
Quoting Hurricanes101:


would be nice if people did not post incorrect information, 130 knots is not a CAT 5


Oh shoot! You're right.

Sorry guys. Memory fail.

No need to get nasty.
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Quoting Goldenblack:
Which update are you referring to Oracle? Maybe we can help?



I guess I'm thinking high doom time. It won't be until 11 PM, I guess. Although, I have a feeling that anything named "Igor" should be considered a likely candidate for high doom.
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2856. angiest
Quoting OracleDeAtlantis:
I wonder why the update is delayed? Rethinking the models, perhaps? A disagreement, maybe?


Next advisory is in an hour.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
Quoting nyhurricaneboy:
BREAKING NEWS: ADT now has Igor at Cat 5 intensity!

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 13 SEP 2010 Time : 004500 UTC
Lat : 17:34:34 N Lon : 47:23:51 W


CI# /Pressure/ Vmax
6.6 / 934.2mb/129.6kt


Final T# Adj T# Raw T#
6.6 6.6 6.6

Latitude bias adjustment to MSLP : +2.0mb

Estimated radius of max. wind based on IR : 24 km

Center Temp : +16.3C Cloud Region Temp : -69.6C

Scene Type : EYE

Positioning Method : RING/SPIRAL COMBINATION

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

Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : OFF
Rapid Dissipation Flag : OFF



would be nice if people did not post incorrect information, 130 knots is not a CAT 5
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Pottery,

You are correct. And for those of you who think that we might be alarmist, we are not alarming, just observing what influences might be causing Igor to wobble a little south of path at this point.

Quoting pottery:

That's something to be concerned about.....
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2853. Vero1
I think that is IGOR on the right.

Member Since: July 21, 2008 Posts: 4 Comments: 2233
2852. shawn26
I was only referring to the 6 models that the Wunderground posts.
Member Since: Posts: Comments:
**CORRECTED: 150 mph*** -NY

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 13 SEP 2010 Time : 004500 UTC
Lat : 17:34:34 N Lon : 47:23:51 W


CI# /Pressure/ Vmax
6.6 / 934.2mb/129.6kt


Final T# Adj T# Raw T#
6.6 6.6 6.6

Latitude bias adjustment to MSLP : 2.0mb

Estimated radius of max. wind based on IR : 24 km

Center Temp : 16.3C Cloud Region Temp : -69.6C

Scene Type : EYE

Positioning Method : RING/SPIRAL COMBINATION

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

Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : OFF
Rapid Dissipation Flag : OFF

Member Since: Posts: Comments:
Quoting shawn26:
Half of the models have it coming bsck towards the U.S. now


WHAT!!!!
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Cloud tops are warming slightly along the SW semicircle.

Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting BiloxiIsle:
So far the northern GOM has been very fortunate this year. Do you think we can make it til the end of the season still feeling lucky?
By the grace of God hun! So far so good. Just need to keep on hanging in there and pray for the best!
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My brother left on Saturday for a cruise to Puerto Rico. I don't know when the ship is supposed to doc. Igor will be close enough to PR to bring some big waves though. I am thinking in the 10-15 ft range so you might end up with a lot of sea-sick passengers.
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It looks like Igor is taking another jog to the wsw.
Link
Member Since: August 9, 2009 Posts: 10 Comments: 5026

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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.