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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That blob over
Quoting Chicklit:
If Igor goes annular all bets are off.
Night folks. It's been an unsettling day.

And what the heck is that blob over Africa?!

good grief.


That blob over Afirca make Igor look like an invest
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Thankies
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So far we have 3 major hurricanes and all of them are Category 4s.
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Quoting Hurricanes101:


Igor is too far east for them to do recon on, has nothing to do with not being concerned
Theyd run out of gas on the way back.
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Quoting Levi32:


That would make sense. It is reflected in the deep-layer steering as well.



That steering would also take 92L westward in the long term. Correct?
Member Since: September 10, 2007 Posts: 0 Comments: 11285
Stormchaser, it is.
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2690. Levi32
Quoting Inactivity:
Drak,Levi, A couple of things
1.Could I wake up to a cat-5 hurricane?
2.What is the chance of Igor going under an EWRC?if so,when?if not-why?

Thanks in advance:)


1. Yes.

2. Igor is nearly annular, which means he has a structure that is highly resistant to EWRCs. In other words, unless he is exposed to a negative factor (dry air, wind shear, cold water), he likely won't undergo an EWRC. He will simply remain this way, either annular or nearly annular, and maintain a nearly constant intensity once he peaks, with minor fluctuations until he begins recurving. Hurricane Isabel in 2003 trekked for days across the Atlantic at Cat 4/5 intensity with little change in structure when she was annular, with no EWRCs.
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2689. mbjjm
Quoting DarIvy959810:

Like EARL isn't it


Earl was further South, Igor already at 17N well north of the Islands
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Quoting Stormchaser2007:
Is Barometer Bob's show on now?


Yes, StormW's on.
Member Since: July 8, 2005 Posts: 259 Comments: 24200
2687. angiest
Quoting Chicklit:
If Igor goes annular all bets are off.
Night folks. It's been an unsettling day.

And what the heck is that blob over Africa?!

good grief.


TD12/Julia looks like a bean.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
Is Barometer Bob's show on now?
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Quoting washingtonian115:
May you tell me what that stands for please.Thank you.
Look around post 2481, and there is an expanded version of that line item..lol
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Quoting mbjjm:


None of the models take Igor near the US.
Computers

Like EARL isn't it
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If Igor goes annular all bets are off.
Night folks. It's been an unsettling day.

And what the heck is that blob over Africa?!

good grief.
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2682. xcool
traumaboyy lol
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting tinkahbell:
Link please for BB's show...


Here you go. Link
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Quoting xcool:
traumaboyy .poor babyyy lol


LOL....buy you own stinking Beer...lol
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i think we may see a cat 5 at 11 pm
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Quoting dracko19:
Looks like NHC is more worried about the Carribean than IGOR.

000
NOUS42 KNHC 111530
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1130 AM EDT SAT 11 SEPTEMBER 2010
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 12/1100Z TO 13/1100Z SEPTEMBER 2010
TCPOD NUMBER.....10-103

I. ATLANTIC REQUIREMENTS
1. SUSPECT AREA (CENTRAL CARIBBEAN)
FLIGHT ONE -- TEAL 70
A. 12/1800Z
B. AFXXX 01EEA INVEST
C. 12/1145Z
D. 15.5N 70.0W
E. 12/1700Z TO 12/2100Z
F. SFC TO 10,000 FT

FLIGHT TWO -- TEAL 71
A. 13/0600,1200Z
B. AFXXX 0212A CYCLONE
C. 13/0400Z
D. 16.2N 74.4W
E. 13/0500Z TO 13/1200Z
F. SFC TO 15,000 FT

2. SUCCEEDING DAY OUTLOOK: CONTINUE 6-HRLY FIXES IF
SYSTEM DEVELOPS.
3. REMARKS: SEVERAL RESEARCH FLIGHTS ARE PLANNED
FOR THE CENTRAL CARIBBEAN SUSPECT AREA.
A. THE NSF/NCAR G-V WILL FLY A 7 HR MISSION BETWEEN
41,000 AND 43,000 FT WITH TAKEOFF AT 12/1100Z.
B. THE NASA GLOBAL HAWK WILL FLY A 24 HR MISSION
ABOVE 58,000 FT WITH TAKEOFF AT 12/1130Z.
C. THE NOAA G-IV WILL FLY AN 8 HR MISSION BETWEEN
41,000 AND 45,000 FT WITH TAKEOFF AT 12/1730Z.
D. THE NASA DC-8 WILL FLY AN 8 HR MISSION BETWEEN
35,000 AND 39,000 FT WITH TAKEOFF AT 12/1800Z.
E. NOAA 43 AND 42 P-3 AIRCRAFT WILL BEGIN A SERIES
OF MISSIONS BETWEEN 7,000 AND 12,000 FT WITH
TAKEOFFS AT 12/2000Z AND 13/0800Z...RESPECTIVELY.



Igor is too far east for them to do recon on, has nothing to do with not being concerned
Member Since: March 10, 2010 Posts: 1 Comments: 7826
2676. mbjjm
Earl was a different beast.
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Quoting bird72:


12/2345 UTC 17.6N 47.2W T6.5/6.5 IGOR -- Atlantic

Dvorak numbers put him on 17.6
May you tell me what that stands for please.Thank you.
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2674. xcool
traumaboyy .poor babyyy lol
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting Flyairbird:
Isnt that what they said about Earl?

I think so
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Link please for BB's show...
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Drak,Levi, A couple of things
1.Could I wake up to a cat-5 hurricane?
2.What is the chance of Igor going under an EWRC?if so,when?if not-why?

Thanks in advance:)
Member Since: Posts: Comments:
Quoting mbjjm:


None of the models take Igor near the US.
Computers
Isnt that what they said about Earl?
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Quoting Chicklit:
Isn't there one right behind Igor doing about the same thing? That one ramped up even sooner than Iggy did.


That would be TS Julia.
Member Since: July 8, 2005 Posts: 259 Comments: 24200
Link

This is one of the lass satellite photos from Igor. Can anyone tell me where isd the center?
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Hell with Igor, we got a home bread system coming into the Gulf end of the week
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Quoting WeatherNerdPR:

Igor is living up to his name...
Exactly.He's a real beast tonight.
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2665. Levi32
Quoting Drakoen:


If you look at the water vapor imagery out ahead of the storm you can see that the mid to upper level flow is coming down from northeast which may be why it is taking that jog south of due west.


That would make sense. It is reflected in the deep-layer steering as well.

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Quoting hurricanehunter27:
You guys all know it is a Cat 5 right now. The only reason the NHC would not put it at Cat 5 is if it goes through EWR. I bet the winds on Igor are at 160-170mph it is a beast of a storm. The IR sat shows a perfect eye and a nice ring of convection. To me this is the strongest storm iv seen other than rita and wilma.


Well let's home UNLIKE Wilma and Rita it's not a landfalling storm..this would be a nasty scene.
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2663. bird72
Quoting RecordSeason:
Yeah, you can definitely see a significant drift to the south over the past 7 hours on shortwave IR.

Perhaps 0.1 to 0.15 degrees lattitude farther south than at mid day...

Link


12/2345 UTC 17.6N 47.2W T6.5/6.5 IGOR -- Atlantic

Dvorak numbers put him on 17.6
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Satellite imagery reveals that Igor's eye is contracting and getting better defined while jogging slightly towards the WSW.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting weatherwart:


Yeah. It's good.


Dam no speakers on computer here at work :(
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MODIS

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2659. angiest
Quoting dracko19:
Looks like NHC is more worried about the Carribean than IGOR.

000
NOUS42 KNHC 111530
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1130 AM EDT SAT 11 SEPTEMBER 2010
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 12/1100Z TO 13/1100Z SEPTEMBER 2010
TCPOD NUMBER.....10-103

I. ATLANTIC REQUIREMENTS
1. SUSPECT AREA (CENTRAL CARIBBEAN)
FLIGHT ONE -- TEAL 70
A. 12/1800Z
B. AFXXX 01EEA INVEST
C. 12/1145Z
D. 15.5N 70.0W
E. 12/1700Z TO 12/2100Z
F. SFC TO 10,000 FT

FLIGHT TWO -- TEAL 71
A. 13/0600,1200Z
B. AFXXX 0212A CYCLONE
C. 13/0400Z
D. 16.2N 74.4W
E. 13/0500Z TO 13/1200Z
F. SFC TO 15,000 FT

2. SUCCEEDING DAY OUTLOOK: CONTINUE 6-HRLY FIXES IF
SYSTEM DEVELOPS.
3. REMARKS: SEVERAL RESEARCH FLIGHTS ARE PLANNED
FOR THE CENTRAL CARIBBEAN SUSPECT AREA.
A. THE NSF/NCAR G-V WILL FLY A 7 HR MISSION BETWEEN
41,000 AND 43,000 FT WITH TAKEOFF AT 12/1100Z.
B. THE NASA GLOBAL HAWK WILL FLY A 24 HR MISSION
ABOVE 58,000 FT WITH TAKEOFF AT 12/1130Z.
C. THE NOAA G-IV WILL FLY AN 8 HR MISSION BETWEEN
41,000 AND 45,000 FT WITH TAKEOFF AT 12/1730Z.
D. THE NASA DC-8 WILL FLY AN 8 HR MISSION BETWEEN
35,000 AND 39,000 FT WITH TAKEOFF AT 12/1800Z.
E. NOAA 43 AND 42 P-3 AIRCRAFT WILL BEGIN A SERIES
OF MISSIONS BETWEEN 7,000 AND 12,000 FT WITH
TAKEOFFS AT 12/2000Z AND 13/0800Z...RESPECTIVELY.



What's the farthest east they do recon?
Member Since: August 26, 2006 Posts: 16 Comments: 4766
2658. mbjjm
Quoting WeatherMSK:
Definately starting to worry about Igor because the models are now starting to depict that WNW-NW turn and then back to a W heading right around 65W that I was thinking would happen yesterday. That puts the east coast at threat as I do think all the models will continue to trend west in general.



None of the models take Igor near the US.
Computers
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Quoting xcool:




....ehhhh,some of those models are starting to turn due west at the end(dynamical)......that can't be a good trend for the se...,
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Quoting MZT:
Even leaving aside discussion of model shifts to the west ... extrapolating the current curvature of the models could still be a landfall on Nova Scotia or Labrador.
Again?
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Quoting KoritheMan:


If it's going to do so, it needs to do so before it runs into the Yucatan. I'm starting to have my doubts, but I still think it has a decent chance.
Oh. I have mine too. That's why I asked. It seems as if it's been trying to do so. I have no clue why it hasn't acquired additional strengthening over an area that has marvelous conditions for a catastrophic cyclone to form. But, it hasn't taken advantage of that. I wonder if it will be another Alex and be an awful looking storm then get to the NW Caribbean, and just explode and become a massive storm. Not out of the question.
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Isn't there one right behind Igor doing about the same thing? That one ramped up even sooner than Iggy did.
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2653. angiest
Igor is marginally annular:

## ANNULAR HURRICANE INDEX (AHI) AL112010 IGOR 09/13/10 00 UTC ##
## PASSED SCREENING STEP, MIGHT BE ANNULAR, CALCULATE AHI FROM DISCRIMINANT ANALYSIS ##
## AHI= 1 (AHI OF 100 IS BEST FIT TO ANN. STRUC., 1 IS MARGINAL, 0 IS NOT ANNULAR) ##
## ANNULAR INDEX RAN NORMALLY
Member Since: August 26, 2006 Posts: 16 Comments: 4766
Quoting Drakoen:


If you look at the water vapor imagery out ahead of the storm you can see that the mid to upper level flow is coming down from northeast which may be why it is taking that jog south of due west.


Exactly.
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Quoting traumaboyy:


Where are you listening to the Chief??....Is the BB show on??


Yeah. It's good.
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At 130kt, Igor is contributing 1.6900 in ACE every 6 hour (complete) advisory. To put it into perspective, that's more than all of what Hermine and Gaston contributed in total.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Looks like NHC is more worried about the Carribean than IGOR.

000
NOUS42 KNHC 111530
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1130 AM EDT SAT 11 SEPTEMBER 2010
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 12/1100Z TO 13/1100Z SEPTEMBER 2010
TCPOD NUMBER.....10-103

I. ATLANTIC REQUIREMENTS
1. SUSPECT AREA (CENTRAL CARIBBEAN)
FLIGHT ONE -- TEAL 70
A. 12/1800Z
B. AFXXX 01EEA INVEST
C. 12/1145Z
D. 15.5N 70.0W
E. 12/1700Z TO 12/2100Z
F. SFC TO 10,000 FT

FLIGHT TWO -- TEAL 71
A. 13/0600,1200Z
B. AFXXX 0212A CYCLONE
C. 13/0400Z
D. 16.2N 74.4W
E. 13/0500Z TO 13/1200Z
F. SFC TO 15,000 FT

2. SUCCEEDING DAY OUTLOOK: CONTINUE 6-HRLY FIXES IF
SYSTEM DEVELOPS.
3. REMARKS: SEVERAL RESEARCH FLIGHTS ARE PLANNED
FOR THE CENTRAL CARIBBEAN SUSPECT AREA.
A. THE NSF/NCAR G-V WILL FLY A 7 HR MISSION BETWEEN
41,000 AND 43,000 FT WITH TAKEOFF AT 12/1100Z.
B. THE NASA GLOBAL HAWK WILL FLY A 24 HR MISSION
ABOVE 58,000 FT WITH TAKEOFF AT 12/1130Z.
C. THE NOAA G-IV WILL FLY AN 8 HR MISSION BETWEEN
41,000 AND 45,000 FT WITH TAKEOFF AT 12/1730Z.
D. THE NASA DC-8 WILL FLY AN 8 HR MISSION BETWEEN
35,000 AND 39,000 FT WITH TAKEOFF AT 12/1800Z.
E. NOAA 43 AND 42 P-3 AIRCRAFT WILL BEGIN A SERIES
OF MISSIONS BETWEEN 7,000 AND 12,000 FT WITH
TAKEOFFS AT 12/2000Z AND 13/0800Z...RESPECTIVELY.

Member Since: Posts: Comments:
2648. MZT
Even leaving aside discussion of model shifts to the west ... extrapolating the current curvature of the models could still be a landfall on Nova Scotia or Labrador.
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Quoting weatherwart:


Levi, I'm listening to Storm and he has the same concerns. He's favoring the south tracks at this point and is concerned about that second high without a trof to pull Igor north.


Where are you listening to the Chief??....Is the BB show on??
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woah, either levi or StormW, after going NW for a while is Pre-julia expected to make a sharp turn to the west?

also, if not, why do during the life of the systems recently a lot of the models runs show this for a couple runs but back off of it and it never happens.

also, what are the chances of a high building in and having igor hit florida?
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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.