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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4051. Neapolitan 12:54 PM GMT on September 14, 2010    
Quoting KEEPEROFTHEGATE:
it appears cv season is coming to an end we have reach the caboose and its dropping south


Not sure whether it was you either time, but that's the same thing I heard on here last week, and the week before. ;-) My own guess is that the Indian butterfly who'll flap his wings to create the micro disturbance that'll cascade to turn into the wave that eventually becomes the caboose that moves into the Atlantic and grows into a high-letter storm sill hasn't done so yet. IOW, a few more weeks...
Member Since: November 8, 2009 Posts: 4 Comments: 11166
4052. TropicalAnalystwx13 12:54 PM GMT on September 14, 2010    
Quoting KEEPEROFTHEGATE:
been watching a long time i know the signs mark my words we have reached the end now we look and watch for home grown storms that track n ne in the basin to take us into the fall and the end of the season


Okay...Well there are still a couple of waves worth watcing over Africa.

But its almost time for the home-grown development, and when it happens, the US of A better watch out. :o
Member Since: July 6, 2010 Posts: 89 Comments: 25340
4053. divdog 12:54 PM GMT on September 14, 2010    
Quoting TropicalAnalystwx13:


You must REALLY be an idiot!
you are being kind.
Member Since: August 22, 2008 Posts: 0 Comments: 755
4056. Bonedog 12:55 PM GMT on September 14, 2010    
any bouys in the area of Igor? I looked at the map and didnt notice any NOAAs but does anyone know if we have a floating research one around there?

Would love to know whats going on in that eye.
Member Since: July 14, 2005 Posts: 14 Comments: 7418
4058. weatherwart 12:55 PM GMT on September 14, 2010    
Quoting TropicalAnalystwx13:


Yeah, its awesome, you can tell me. This is from yesterday when Igor was his strongest.

lol


Wow! Awesome animation. Nature at its finest.
Member Since: August 18, 2008 Posts: 0 Comments: 873
4059. Chicklit 12:55 PM GMT on September 14, 2010    

Member Since: July 11, 2006 Posts: 14 Comments: 10255
4060. stormhank 12:56 PM GMT on September 14, 2010    
Not trying to get off topic but has anyone herd the type winter we may have here in the southern US??? I saw a few graphs from cliamte prediction center showing mild and dry??
Member Since: September 8, 2005 Posts: 0 Comments: 1375
4061. Neapolitan 12:56 PM GMT on September 14, 2010    
92L pressure down again to 1006, and winds finally up to 30 knots:

AL, 92, 2010091412, , BEST, 0, 175N, 822W, 30, 1006, DB, 34, NEQ, 0, 0, 0, 0, 1009, 180, 70, 0, 0, L, 0, , 0, 0, INVEST, S
Member Since: November 8, 2009 Posts: 4 Comments: 11166
4063. TropicalAnalystwx13 12:56 PM GMT on September 14, 2010    
92L:

Member Since: July 6, 2010 Posts: 89 Comments: 25340
4064. weaverwxman 12:56 PM GMT on September 14, 2010    
Quoting EnergyMoron:
Steering looks "normal" again...

Link

So, think about it... what was happening with the steering yesterday?

it was low on power steering fluid just fill the reservoir
Member Since: November 17, 2009 Posts: 0 Comments: 332
4065. scott39 12:56 PM GMT on September 14, 2010    
StormW have looked at 92L in the last hour? Looks to be organizing more?
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4066. lou60carol 12:57 PM GMT on September 14, 2010    
igorlooks like he can get closer to the carolinas and up the east coast?IGOR STILL MOVEING WNW NOT NORTH SO HE CAN GET CLOSER TO THE EAST COAST?
Member Since: July 20, 2010 Posts: 1 Comments: 6
4067. DaytonaBeachWatcher 12:57 PM GMT on September 14, 2010    
Quoting Neapolitan:
92L pressure down again to 1006, and winds finally up to 30 knots:

AL, 92, 2010091412, , BEST, 0, 175N, 822W, 30, 1006, DB, 34, NEQ, 0, 0, 0, 0, 1009, 180, 70, 0, 0, L, 0, , 0, 0, INVEST, S


Here we Gooooooooooo!
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4070. DaytonaBeachWatcher 12:58 PM GMT on September 14, 2010    
Quoting TropicalAnalystwx13:
92L:



Popping some nice convection there, interesting to see if we get a surface circulation today.
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4071. CybrTeddy 12:58 PM GMT on September 14, 2010    
Two hurricanes.
Member Since: July 8, 2005 Posts: 253 Comments: 20276
4072. scott39 12:58 PM GMT on September 14, 2010    
92L looks to be moving more WNW now.
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4073. FlyingScotsman 12:59 PM GMT on September 14, 2010    
Quoting barotropic:


What an awesome loop...it doesn't get any better than that!!


That is flat-out gorgeous! Thanks for posting that, TropicalAnalystwx13. Is there any way I can download that loop?
Member Since: September 1, 2010 Posts: 5 Comments: 144
4074. KEEPEROFTHEGATE (Mod) 12:59 PM GMT on September 14, 2010    
Quoting Neapolitan:


Not sure whether it was you either time, but that's the same thing I heard on here last week, and the week before. ;-) My own guess is that the Indian butterfly who'll flap his wings to create the micro disturbance that'll cascade to turn into the wave that eventually becomes the caboose that moves into the Atlantic and grows into a high-letter storm sill hasn't done so yet. IOW, a few more weeks...
no i never said it before its the first time and even climo rules say there is about 14 days left to get cv action after that its done
Member Since: July 15, 2006 Posts: 144 Comments: 40644
4075. StormJunkie 12:59 PM GMT on September 14, 2010    
Ok, y'all have fun. I must "poof" myself to class so that I can attain that college degree I should have gotten years ago.

See everyone later.
Member Since: August 17, 2005 Posts: 26 Comments: 15218
4076. DaytonaBeachWatcher 1:00 PM GMT on September 14, 2010    
Plan of the Day
--------------------------------------------------------------------------------


000
NOUS42 KNHC 131550
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1150 AM EDT MON 13 SEPTEMBER 2010
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 14/1100Z TO 15/1100Z SEPTEMBER 2010
TCPOD NUMBER.....10-105

I. ATLANTIC REQUIREMENTS
1. SUSPECT AREA (CARIBBEAN)
FLIGHT ONE -- TEAL 70
A. 14/1800Z
B. AFXXX 01EEA INVEST
C. 14/1500Z
D. 18.0N 84.0W
E. 14/1730Z TO 14/2100Z
F. SFC TO 10,000 FT

FLIGHT TWO -- TEAL 71
A. 15/0600,1200Z
B. AFXXX 0213A CYCLONE
C. 15/0245Z
D. 19.0N 86.5W
E. 15/0530Z TO 15/1200Z
F. SFC TO 15,000 FT



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4078. futuremet 1:00 PM GMT on September 14, 2010    
Member Since: July 19, 2008 Posts: 43 Comments: 4049
4079. hercj 1:01 PM GMT on September 14, 2010    
Quoting StormW:
Here's your pattern change


Senior, the ridge moves to the east?
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4080. weatherwart 1:01 PM GMT on September 14, 2010    
Quoting stormhank:
Not trying to get off topic but has anyone herd the type winter we may have here in the southern US??? I saw a few graphs from cliamte prediction center showing mild and dry??


Personlly I loved last winter. I had snowflakes and sleet on my land in west central Florida. Didn't love the well pump freezing too much, though.
Member Since: August 18, 2008 Posts: 0 Comments: 873
4081. TropicalAnalystwx13 1:01 PM GMT on September 14, 2010    
Quoting stormhank:
Not trying to get off topic but has anyone herd the type winter we may have here in the southern US??? I saw a few graphs from cliamte prediction center showing mild and dry??


Here's my Winter Forecast.

Thats the Temperature forecast. I have to do the precipitation forecast, but overall, the south will have a dry and above average winter.
Member Since: July 6, 2010 Posts: 89 Comments: 25340
4082. hercj 1:01 PM GMT on September 14, 2010    
My bad, west
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4084. gulfbreeze 1:02 PM GMT on September 14, 2010    
Quoting Eugeniopr:


I will be very happy if you are right.
That does not mean the end of the season just the CV part.
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4086. WeatherMSK 1:03 PM GMT on September 14, 2010    
Im curious as to how much Julia will have an impact on Igor's path? Seems like the models punch Julia quickly to Igor's north east. Was thinking if that does not occur I wonder if the azore high would develop further westward since Julia would not be eroding it in that scenario. Thus, forcing Igor back to the west more than what the models show. I think it's something to watch for.

I suppose I am on board with Igor not hitting the east coast, but you just never know. Thought I would put that out there.
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4087. Bonedog 1:03 PM GMT on September 14, 2010    
checking the bouys around 92 no surce circulation yet

S, ESE, E

the east reading was on the north western side

no bouy winds above 18knts either
Member Since: July 14, 2005 Posts: 14 Comments: 7418
4088. TropicalAnalystwx13 1:03 PM GMT on September 14, 2010    
Quoting StormJunkie:
Ok, y'all have fun. I must "poof" myself to class so that I can attain that college degree I should have gotten years ago.

See everyone later.


Yup, I have to "poof" myself to class too. My mom has to drive me though, I'm too young!
Member Since: July 6, 2010 Posts: 89 Comments: 25340
4090. hercj 1:04 PM GMT on September 14, 2010    
That was some interesting reading, thank you both. I now have a small understanding as to why the dynamical models are preferred in forecasting.
Member Since: September 5, 2009 Posts: 0 Comments: 319
4091. PensacolaDoug 1:04 PM GMT on September 14, 2010    
Quoting Neapolitan:


Not sure whether it was you either time, but that's the same thing I heard on here last week, and the week before. ;-) My own guess is that the Indian butterfly who'll flap his wings to create the micro disturbance that'll cascade to turn into the wave that eventually becomes the caboose that moves into the Atlantic and grows into a high-letter storm sill hasn't done so yet. IOW, a few more weeks...


That does it. I'm declaring "open season" on butterfies!
Member Since: July 25, 2006 Posts: 0 Comments: 4828
4093. FormerTigergirl 1:05 PM GMT on September 14, 2010    
Quoting SQUAWK:


Thank you. Now I don't have to put up with your over inflated ego anymore.


LOL...Like you don't hve one too
Member Since: July 6, 2008 Posts: 0 Comments: 63
4095. JamesSA 1:06 PM GMT on September 14, 2010    
I see Igor has made his turn, but that track looks rather bad for Bermuda!

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4096. wayfaringstranger 1:06 PM GMT on September 14, 2010    
Quoting StormW:


Yeah...bouncing back and forth between analysis and looking at it.
Is this close to the loop current? What are the effects of the loop current on this system?
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4097. xcool 1:07 PM GMT on September 14, 2010    
CybrTeddy .and more comeing too rigth home brew.
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4098. gulfbreeze 1:08 PM GMT on September 14, 2010    
The loop curnt is in the Gulf.
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4099. wayfaringstranger 1:10 PM GMT on September 14, 2010    
Quoting gulfbreeze:
The loop curnt is in the Gulf.
but extends south into the carribean right?
Member Since: July 12, 2010 Posts: 0 Comments: 235
4100. FlyingScotsman 1:10 PM GMT on September 14, 2010    
Looking at the latest Dvorak IR loop, Igor seems to have finished his weakening, and might be getting ready to re-strengthen--notice the white convection now north and south of the eye:

Member Since: September 1, 2010 Posts: 5 Comments: 144
4101. PensacolaDoug 1:11 PM GMT on September 14, 2010    
Being in the "bullseye" on a 5-day TPC/NHC forecast usually means a 200-300 mile miss. The exception to that rule is after the storm starts its recurve, then the TPC/NHC track becomes more accurate. In other words, look out Bermuda, probably going to be close!
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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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