Dr. Jeff Masters' WunderBlog

Igor an impressive Cat 4; 92L running out of time to develop; Julia forms
Posted by: Dr. Jeff Masters, 1:47 PM GMT on September 13, 2010 +6
There are few sights in the natural world more impressive than a hurricane near maximum intensity. Hurricane Igor certainly fits that description this morning, as it flirts with Category 5 strength in the Central Atlantic. Igor's rapid intensification burst brought the mighty hurricane's winds to 150 mph, just shy of the 156 mph threshold for Category 5 status. Igor is the strongest hurricane in the Atlantic in three years. The last hurricane stronger that Igor was Category 5 Hurricane Felix of 2007.


Figure 1. Morning satellite image of Igor.

Intensity forecast for Igor
Wind shear is low, 5 - 10 knots, and is expected to remain low for the next four days. Waters are warm, 28.5°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. These conditions should allow Igor to remain at major hurricane status for the next four days. The hurricane will probably undergo one of the usual eyewall replacement cycles intense hurricanes commonly have, where the eyewall collapses and a new eyewall forms from an outer spiral band. This will weaken the hurricane by 10 - 20 mph when it occurs, but Igor will probably regain its lost intensity when the cycle completes. There's no evidence that an eyewall replacement cycle is imminent today, so Igor could potentially strengthen a bit more. However, I believe Igor has peaked, and will not reach Category 5 status today. By Saturday, when Igor should be nearing Bermuda, the trough of low pressure steering Igor northwestwards should bring moderate wind shear of 10 - 20 knots to the storm, weakening it.

Track forecast for Igor
The track forecast for Igor remains unchanged. Igor will move west under the influence of a strong ridge of high pressure until Tuesday morning, 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 appears likely to be a threat to Bermuda, and that island can expect tropical storm force winds as early as Friday. Igor 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 - 10 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 hitting the U.S. or Canada. While the trough expected to recurve Igor out to sea is not as sharp as the troughs that recurved Danielle, Earl, and Fiona, it should still be strong enough to keep Igor from hitting the U.S. However, Newfoundland, Canada could see a close pass. An examination of the tracks of the ten major September hurricanes that have passed closest to Igor's current location (Figure 2) reveals that one of these hurricanes went on to hit the Bahamas and Florida as a Category 2 storm, and another hit Newfoundland as a Category 1 storm. The other eight missed land. One wild card may be the intensification of Julia behind Igor. If Julia develops into a hurricane and moves close to Igor, as some of the models are suggesting, the two hurricanes could interact, affecting the track of Igor unpredictable ways. However, it currently appears the Julia will be much weaker than Igor, and will probably have little impact on her big brother's track.


Figure 2. Historical plot of the tracks of the ten major September hurricanes that have passed closest to Igor's current location.

Caribbean disturbance 92L
Tropical disturbance (92L) over the Central Caribbean, centered about 100 miles south of Jamaica, has changed little over the past day. The storm remains a threat to develop into a tropical depression, but time is running out for it to do so. Satellite loops this morning do not show a surface circulation, but 92L does have a moderate area of intense disorganized thunderstorms that are bringing heavy rain to Jamaica this morning. Kingston, Jamaica has picked up 0.67" of rain thus far this morning from 92L.


Figure 3. Morning satellite image of 92L.

Forecast for 92L
Wind shear over 92L is low, 5 - 10 knots, and is expected to remain low to moderate for the next five days. The waters beneath are hot, 29.8°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 has been interfering with development of 92L. NHC is putting the odds of 92L developing into a tropical depression by Wednesday at 40%. Given the current disorganized state of 92L, it would be difficult for it to intensify quickly enough to become any stronger than a tropical storm with 50 mph winds by Wednesday, when it will move over Belize and Mexico's Yucatan Peninsula. 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 several hundred miles south of the Texas border. A Hurricane Hunter aircraft is scheduled to investigate 92L this afternoon.

Julia
Tropical Storm Julia formed between the Cape Verdes Islands and coast of Africa yesterday, bringing some heavy rain squalls and gusty winds to the Cape Verdes, but no sustained winds of tropical storm force. Julia is headed northwest, out to sea, and it is unlikely that this storm will trouble any land areas . Shear is low enough over the next few days to allow Julia to become a hurricane, but shear will rise sharply 4 - 5 days from now, limiting the potential for Julia to become a major hurricane.

Elsewhere in the tropics
The NOGAPS model is calling for a new tropical depression to form off the coast of Africa 6 - 7 days from now.

Next post
I'll have a new post Tuesday morning.

Jeff Masters
Categories: Hurricane
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3801. yacoub 11:23 AM GMT on September 14, 2010    
3758. StormW -- you know, the way it was tracking south-west, which clearly indicated it was headed north. ;P
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3802. ncstorm 11:23 AM GMT on September 14, 2010    
Today's breakfast menu:

Humble Pie $$small ego.00

Small, Medium and Large slices are available.

Im glad to see Igor taking that turn!




Member Since: August 19, 2006 Posts: 7 Comments: 8462
3803. MahFL 11:24 AM GMT on September 14, 2010    
One of these days FL will be in the cone, and then all hell will break out !
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3804. scott39 11:24 AM GMT on September 14, 2010    
Quoting victoria780:
Looks better every hr,92l of coarse,maybe s-pattern developing or should I say (K)
HWRF model does the "S"
Member Since: June 13, 2009 Posts: 0 Comments: 6207
3805. Chicklit 11:24 AM GMT on September 14, 2010    
Quoting scott39:
92L heading WNW at 288 degrees. I wonder if this is just a show of convection this morning, or some organization starting to happen?


vorticity map
Member Since: July 11, 2006 Posts: 14 Comments: 10254
3806. Bonedog 11:25 AM GMT on September 14, 2010    
I figured it out. Igor was spawned by CERN!!

Truely a black hole on Earth



again I will say I would LOVE to fly in that eye. I wish he was closer so the HH could get in their and shoot some rolls.
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3809. scott39 11:26 AM GMT on September 14, 2010    
Quoting Chicklit:


vorticity map
Looks healthier.
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3810. stormwatcherCI 11:26 AM GMT on September 14, 2010    



92L. Looks like a pretty well defined circulation between 17/18N and 81W. No convection on the eastern side. Conditions in Grand Cayman very overcast, raining off and on, winds 20-30 mph and pressure at 1006 mb.
Member Since: October 9, 2008 Posts: 0 Comments: 8040
3811. Mikla 11:27 AM GMT on September 14, 2010    
Quoting StormW:
<


Storm... no need to get defensive... Even the first graphic... 5 days old... the current track is well within the NHC cone.
Member Since: October 13, 2006 Posts: 0 Comments: 201
3813. Relix 11:28 AM GMT on September 14, 2010    
Quoting TropicalBruce:
It continues to looks like the pattern of troughs in the eastern U.S. and western Atlantic has allowed Cape Verde storms to veer north this year before hitting the U.S. directly. It's getting late and as the troughs get stronger, it'll become more difficult for storms originating in the eastern Atlantic to make their way westward. And, time will soon be running out for the African parade of t-waves.

We'll see what happens with whatever late-season storms originate in the Caribbean/Gulf. Those could be the real threats to the U.S. this year.


I think StormW expect this to stop for at least 2 weeks or so.
Member Since: August 3, 2006 Posts: 0 Comments: 2358
3814. weatherwart 11:28 AM GMT on September 14, 2010    
Quoting FLdewey:
LMAO... the blog will be missing 15-20 people today.


Dewey, I meant to tell you this last night. You crack me the hell up. When you did the "I dip you dip we dip" I nearly fell off my chair.

Thank you.
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3815. Chicklit 11:29 AM GMT on September 14, 2010    
Quoting DestinJeff:
It is the One Behind Julia that has me worried!

If not that one, then the next one.


Member Since: July 11, 2006 Posts: 14 Comments: 10254
3816. cajunkid 11:29 AM GMT on September 14, 2010    
Looking at the Dvorak of N. Atlantic, it looks like it hit a brick wall.

NHC has been pretty good this year.
Member Since: July 10, 2005 Posts: 3 Comments: 1239
3817. scott39 11:29 AM GMT on September 14, 2010    
I was just about to get out my rifle and do a mercy killing on 92L last night. I just cant do it now!!
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3820. PensacolaDoug 11:30 AM GMT on September 14, 2010    
If the TPC/NHC says its gonna re-curve, only a fool bets against it.
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3822. stormhank 11:31 AM GMT on September 14, 2010    
anyone feel the US coast will have at least 1 or 2 hurricane landfalls beofre season ends??
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3823. Chicklit 11:31 AM GMT on September 14, 2010    
The NHC is not flying an airplane.
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3824. Cotillion 11:32 AM GMT on September 14, 2010    
Igor again is a wonderful prognosticator.

He predicts the amounts of points the Jets got last night. He did the same with Atlanta, too.

A true AFCN fan.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
3827. luigi18 11:32 AM GMT on September 14, 2010    
Quoting StormW:


Oh please.

Dr Storm Hello looking at the floater i saw Igor jumping to the north after 3 3hours he now move due west for more than 1 hour?
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3828. stormhank 11:33 AM GMT on September 14, 2010    
Link I know this is many days out but still a scary site
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3830. Relix 11:34 AM GMT on September 14, 2010    
Quoting luigi18:

Dr Storm Hello looking at the floater i saw Igor jumping to the north after 3 3hours he now move due west for more than 1 hour?


Stair step effect
Member Since: August 3, 2006 Posts: 0 Comments: 2358
3831. Cotillion 11:34 AM GMT on September 14, 2010    
Quoting stormhank:
anyone feel the US coast will have at least 1 or 2 hurricane landfalls beofre season ends??


Late September/early October is the time to look for that.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
3834. IKE 11:35 AM GMT on September 14, 2010    
Igor going east of the tropical forecast points.

I'm an east-caster.
Member Since: June 9, 2005 Posts: 23 Comments: 37044
3835. Chicklit 11:36 AM GMT on September 14, 2010    
Quoting scott39:
Looks healthier.

Yeah, Scotty. GOM threat?
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3836. Vero1 11:36 AM GMT on September 14, 2010    


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3837. weatherwart 11:36 AM GMT on September 14, 2010    
Quoting DestinJeff:
They call me..

DOCTOR STORRRRRRRRRM

They call me Doctor Storm.

DOCTOR STORRRRRRRRRRM


Jeez, DJ. How much coffee have you had? lmao!
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3838. scott39 11:36 AM GMT on September 14, 2010    
I wouldnt be suprised to see a 1995 Opal "like" track for the Conus this season.
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3839. PensacolaDoug 11:37 AM GMT on September 14, 2010    
Quoting IKE:
Igor going east of the tropical forecast points.

I'm an east-caster.




Troublemaker!!!


lol
Member Since: July 25, 2006 Posts: 0 Comments: 4828
3840. PensacolaDoug 11:37 AM GMT on September 14, 2010    
.
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3841. weatherwart 11:37 AM GMT on September 14, 2010    
Quoting IKE:
Igor going east of the tropical forecast points.

I'm an east-caster.


Is that a change for you, Ike? ;)
Member Since: August 18, 2008 Posts: 0 Comments: 873
3842. Cotillion 11:38 AM GMT on September 14, 2010    
By the end of the day, should surpass 2006 in ACE.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
3844. Chicklit 11:39 AM GMT on September 14, 2010    
Quoting weatherwart:


Jeez, DJ. How much coffee have you had? lmao!

It's not even hump day yet.
Member Since: July 11, 2006 Posts: 14 Comments: 10254
3845. IKE 11:39 AM GMT on September 14, 2010    
Quoting weatherwart:


Is that a change for you, Ike? ;)


Added to...

(1)Down-caster.
(2)East-caster. I'm going east of the model consensus. How often do you read that on this blog? Maybe if it's in the Bay of Campeche.
Member Since: June 9, 2005 Posts: 23 Comments: 37044
3847. WeatherMum 11:40 AM GMT on September 14, 2010    
Jeff, Have you been down at the Donut Hole all morning kicking back their black gold?
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3848. Vero1 11:40 AM GMT on September 14, 2010    
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3850. weatherwart 11:42 AM GMT on September 14, 2010    
Quoting DestinJeff:


After humping the ridge all day yesterday, I've got nuttin' left.


Hahahahhaha!! You and Dewey should take it on the road!
Member Since: August 18, 2008 Posts: 0 Comments: 873
3851. MSKajun 11:42 AM GMT on September 14, 2010    
Mr. StormW, I cannot thank you enough for your expertise on this blog!! You have been very insightful over the years, and my husband and I value your wisdom and knowledge greatly! It disgusts me how people LOVE to push your buttons! Thanks again, and keep up the AWESOME work!
Member Since: September 13, 2008 Posts: 0 Comments: 7

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About JeffMasters
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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