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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1301. MiamiHurricanes09 7:50 PM GMT on September 13, 2010    
Quoting atmoaggie:
Okay. Now that it isn't Sunday, we have a SRSO.

SRSO-Vis

(And more pimples on the SE side, this time.)

They also have an IR version, but it really isn't very interesting and the bandwidth wasted.
Wow, awesome, thanks for letting me know...been waiting for it since yesterday.

Good afternoon everyone!
Member Since: September 2, 2009 Posts: 129 Comments: 19976
1302. barotropic 7:50 PM GMT on September 13, 2010    
Quoting washingtonian115:
Are the models still showing Igor going futher west before turning out to sea?


http://www.ssd.noaa.gov/goes/flt/t1/flash-vis.html

Looks like Igor may indeed make his next forecast point....another wobble North.....see vis float
Member Since: August 22, 2010 Posts: 0 Comments: 652
1303. oracle28 7:51 PM GMT on September 13, 2010    
Quoting Floodman:
My bad, Oracle28 is correct; no direct CONUS landfall for Hermine...though it might just as well have been...


Actually you had it right, I was thinking Earl.
Member Since: July 25, 2008 Posts: 0 Comments: 572
1304. JLPR2 7:51 PM GMT on September 13, 2010    
Quoting sailingallover:
Next 12 hours is critical for the islands after that we won't have much time to move boats and get stuff ready even though most of us have most things still battened down from Earl


But we should get a significant waves event with Igor so moving boats isn't a bad idea.
Member Since: September 4, 2007 Posts: 7 Comments: 7482
1305. dmaddox 7:51 PM GMT on September 13, 2010    
Quoting tacoman:
igor will turn before it gets to 53west...that's where the weakness is at..
at 10mph.. that would occur in roughly 6-8 hours...its possible.. but i dont see it happening...
Member Since: May 5, 2007 Posts: 0 Comments: 445
1307. DaytonaBeachWatcher 7:51 PM GMT on September 13, 2010    
Quoting presslord:
Has Igor started humping the ridge yet?


He is gonna hump it right into the carolinas!
Member Since: June 29, 2007 Posts: 0 Comments: 1125
1308. SevereWeather 7:51 PM GMT on September 13, 2010    
Quoting Tazmanian:
my son Igor has done vary well


lol
Member Since: August 20, 2010 Posts: 0 Comments: 38
1309. islander101010 7:51 PM GMT on September 13, 2010    
92does have some low pressure s of jamaica but is strectched way out like a low level trough very heavy rain down there for sure
Member Since: September 11, 2010 Posts: 0 Comments: 2963
1310. jurakantaino 7:52 PM GMT on September 13, 2010    
Quoting dmaddox:
what else does it have to do to become a cat 5!?? geesh!!
't do to Nothing he can'T do, becoming a CAT 5 to far away, needs a hurricane hunter to prove it, in the mean time, Conservative NHC, will keep in Cat 4...
Member Since: July 31, 2008 Posts: 0 Comments: 730
1311. barotropic 7:52 PM GMT on September 13, 2010    
Quoting barotropic:


http://www.ssd.noaa.gov/goes/flt/t1/flash-vis.html

Looks like Igor may indeed make his next forecast point....another wobble North.....see vis float


May also be suns effect and not going to much in way of north. Have to wait for more pics....
Member Since: August 22, 2010 Posts: 0 Comments: 652
1312. dmaddox 7:52 PM GMT on September 13, 2010    
its really going to have to start heading DUE NW right now if any of these are going to verify... thoughts!??
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1313. ncstorm 7:53 PM GMT on September 13, 2010    
Quoting sailingallover:
Next 12 hours is critical for the islands after that we won't have much time to move boats and get stuff ready even though most of us have most things still battened down from Earl


So if Igor dosent turn, you expect to feel effects in 12 hours if I understood right? wow that isnt a lot of time and the reason I state this is because people are saying the NHC is being conservative about moving the cone but 12 hours isnt a whole lot of time to play the what if game on Igor turning especially with the Islands so close in location to Igor, especially a potential Cat 5 storm..
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1314. JLPR2 7:53 PM GMT on September 13, 2010    
So anyone who knows how to read this better than me, is this update good or bad? XD

Member Since: September 4, 2007 Posts: 7 Comments: 7482
1315. hydrus 7:53 PM GMT on September 13, 2010    
Quoting presslord:
Has Igor started humping the ridge yet?
Word is he wants to get hitched first....I have not seen any northward movement yet....How are things in the Caro.....I just cant...
Member Since: September 27, 2007 Posts: 1 Comments: 14238
1317. washingtonian115 7:53 PM GMT on September 13, 2010    
Quoting Floodman:
My bad, Oracle28 is correct; no direct CONUS landfall for Hermine...though it might just as well have been...
It still cuased damage,and I'm sure the people in it's path won't foreget it anytime soon.Hermine will not be retired I'm sure of it?.Only one tropical storm holds that place,and that's Alison?
Member Since: August 14, 2010 Posts: 5 Comments: 10585
1318. JLPR2 7:53 PM GMT on September 13, 2010    
So anyone who knows how to read this better than me, is this update good or bad? XD

Member Since: September 4, 2007 Posts: 7 Comments: 7482
1319. StormJunkie 7:53 PM GMT on September 13, 2010    
OH NO! The current motion is still S of W...He's headed for the HeRbert Box!

Sarcasm Flag: ON



Relax all...There's only about a 1% chance he doesn't turn...
Member Since: August 17, 2005 Posts: 26 Comments: 15218
1320. atmoaggie 7:54 PM GMT on September 13, 2010    
Quoting MiamiHurricanes09:
Wow, awesome, thanks for letting me know...been waiting for it since yesterday.

Good afternoon everyone!
No prob. Refresh it from time to time. SRSO until 22:00 UTC.

(and save that link. Grapevine says RSO scheduled for daytime tomorrow, too. Same link.)
Member Since: August 16, 2007 Posts: 6 Comments: 12461
1321. Seflhurricane 7:54 PM GMT on September 13, 2010    
Quoting MiamiHurricanes09:
Wow, awesome, thanks for letting me know...been waiting for it since yesterday.

Good afternoon everyone!
hey miami still no turn with Igor still moving West
Member Since: July 14, 2009 Posts: 0 Comments: 2898
1324. sailingallover 7:54 PM GMT on September 13, 2010    
Quoting JLPR2:


But we should get a significant waves event with Igor so moving boats isn't a bad idea.

This is true if you have any exposure to the N or NW
The surf will be crazy....
Member Since: September 1, 2009 Posts: 23 Comments: 982
1325. clwstmchasr 7:54 PM GMT on September 13, 2010    
Quoting DaytonaBeachWatcher:
My personal opionion, it wont come as close to the islands as Earl did. Just sayin.


I totally agree. They should get some big waves on the north facing islands.
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1326. originalLT 7:55 PM GMT on September 13, 2010    
Yep, I think a slight WNW movement is noted, lets see if this is more than a wobble.
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1327. Seflhurricane 7:56 PM GMT on September 13, 2010    
Quoting JLPR2:
So anyone who knows how to read this better than me, is this update good or bad? XD

still does not look good
Member Since: July 14, 2009 Posts: 0 Comments: 2898
1329. dmaddox 7:56 PM GMT on September 13, 2010    
Quoting StormJunkie:
OH NO! The current motion is still S of W...He's headed for the HeRbert Box!

Sarcasm Flag: ON



Relax all...There's only about a 1% chance he doesn't turn...
i believe he will recurve but not at the timing and degree the 12z models were predicting! LOL thats pretty extreme given the current situation
Member Since: May 5, 2007 Posts: 0 Comments: 445
1330. StormJunkie 7:56 PM GMT on September 13, 2010    
Quoting presslord:
Has Igor started pumping the ridge yet? ooopppsss


Dude! That must be why he isn't turning! OMG!

Sticks head in sand. At least what's left after Earl took some.
Member Since: August 17, 2005 Posts: 26 Comments: 15218
1332. TheDawnAwakening 7:57 PM GMT on September 13, 2010    
Outflow has expanded tremendously on the western side of the storm. I think he is moistening up the atmosphere to his west and he is expanding outward in size.
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1333. Drakoen 7:57 PM GMT on September 13, 2010    
Microwave imagery reveals that Igor is not going through an EWRC. The core remains well-defined:

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1334. reedzone 7:57 PM GMT on September 13, 2010    
As I stated earlier yesterday, I believe Igor will turn when he reaches 53-55W, which may actually verify by looking at the visible. I don't see a north motion at all. What I see is the eye expanding, tricking others to believe it has started a slight northward jog, but in reality, it's still moving due west. Not south, not north, just west :)
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1335. Hurricanes101 7:57 PM GMT on September 13, 2010    
vorticity increasing with 92L
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1336. islander101010 7:57 PM GMT on September 13, 2010    
stair steppin time
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1337. washingtonian115 7:57 PM GMT on September 13, 2010    
Quoting barotropic:


http://www.ssd.noaa.gov/goes/flt/t1/flash-vis.html

Looks like Igor may indeed make his next forecast point....another wobble North.....see vis float
Thank you.Why are their so many rude people on when I get on.I can never catch the good bloggers.
Member Since: August 14, 2010 Posts: 5 Comments: 10585
1338. JLPR2 7:57 PM GMT on September 13, 2010    
Quoting Seflhurricane:
still does not look good


I was thinking bad, I dont like how that high over the bahamas is building towards the east
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1339. MississippiBoy2 7:57 PM GMT on September 13, 2010    
Quoting Seflhurricane:
still does not look good
for who?
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1340. Drakoen 7:58 PM GMT on September 13, 2010    
Member Since: October 28, 2006 Posts: 57 Comments: 29010
1341. LADobeLady 7:58 PM GMT on September 13, 2010    
Quoting StormJunkie:


Dude! That must be why he isn't turning! OMG!

Sticks head in sand. At least what's left after Earl took some.


Oh wow you nailed it! Igor is a Zombie not a hurricane!
Member Since: July 29, 2005 Posts: 21 Comments: 794
1342. washingtonian115 7:58 PM GMT on September 13, 2010    
Quoting barotropic:


http://www.ssd.noaa.gov/goes/flt/t1/flash-vis.html

Looks like Igor may indeed make his next forecast point....another wobble North.....see vis float
Thank you.Why are their so many rude people on when I get on.I can never catch the good bloggers.
Member Since: August 14, 2010 Posts: 5 Comments: 10585
1343. NOLALawyer 7:58 PM GMT on September 13, 2010    
Engineering, technology, computer science and a deep understanding of meteorlogical tenets mean nada in the face of mother nature. Storms go where storms go. They don't always adhere to rules. You can turn on all the storm shields, deflector shields and hair dryers you would like. You can stand by the models and the current data until you spit wooden nickels. It won't make a difference. None of us can influence where this storm is headed. The precious models say it should be hooking a pretty hard right at this moment....and it is trucking straight.

We will see.
Member Since: September 3, 2009 Posts: 0 Comments: 517
1344. clwstmchasr 7:58 PM GMT on September 13, 2010    
Quoting Seflhurricane:
still does not look good


What are you implying?
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1345. Vero1 7:58 PM GMT on September 13, 2010    
Quoting sailingallover:

This is true if you have any exposure to the N or NW
The surf will be crazy....




Images last updated: Monday, 13 Sep 2010 16:53:51 GMT
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1347. TheDawnAwakening 7:59 PM GMT on September 13, 2010    
Link

He is still going westward, no WNW turn noted.
Member Since: October 21, 2008 Posts: 215 Comments: 3159
1348. sailingallover 7:59 PM GMT on September 13, 2010    
Quoting JLPR2:
So anyone who knows how to read this better than me, is this update good or bad? XD


Bad..shows pretty strong mid to upper level ridging north of Igor
Member Since: September 1, 2009 Posts: 23 Comments: 982
1349. charlestonscnanny 8:00 PM GMT on September 13, 2010    
Does anybody have Bastardi's comments for today?
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1350. washingtonian115 8:00 PM GMT on September 13, 2010    
Quoting FLdewey:
Oz won't even have to dust off the suit for Igor.
It's been in his closet all summer long collecting dust.
Member Since: August 14, 2010 Posts: 5 Comments: 10585
1351. MiamiHurricanes09 8:00 PM GMT on September 13, 2010    
Quoting Drakoen:
Microwave imagery reveals that Igor is not going through an EWRC. The core remains well-defined:

Yeah, should be able to manage category 5 intensity considering the environmental conditions...don't know why he hasn't done so yet.
Member Since: September 2, 2009 Posts: 129 Comments: 19976

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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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