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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I believe the NHC believes that Igor will track just to the west of Bermuda. That would mean that Bermuda gets the eastern eyewall.

As a major hurricane, also...
Member Since: July 6, 2010 Posts: 113 Comments: 32830
Quoting cat5hurricane:
Agreed
when is igor going to go thru his EWRC
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2005 had an ACE of 248.1. 2004 had an ACE OF 225, AND 1995 had an ACE of 227.4. And as of Sept. 13 2010 we have an ACE OF 70.5. So still have a lot of catching up to do.
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Quoting LPstormspotter2:


LPStormspotter... had the yellow race car as the avatar


Hmmm...Have you tried emailing Jeff himself?
Member Since: July 6, 2010 Posts: 113 Comments: 32830
Good Morning Hurricane Fans!!

Igor is veeeeerrrry impressive on visible. Check it out!!

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That's a pretty major oops. Wondering why no one has corrected it.
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A brief rundown:

--2010's ACE now stands at 72.285. That puts this year ahead of current "active" season years '97, '09, and '02, and ties it with '07.

--Depending on what Igor and Julia do, this season's ACE will surpass 2006's sometime tomorrow.

--The mean average ACE for the active period is 101. Again, depending on a few factors, 2010 may surpass that sometime late this week. (next up is 2001).

--Igor has now been a hurricane for six TWOs, and a major hurricane for three. By way of comparison, Alex was a hurricane for six TWOs, Danielle was a hurricane for 27 (and a major for four), and Earl was a hurricane for 22 TWO (a major for 14).

--Since 8/22 (a 23-day span), seven storms have been named, or one every 3.29 days. (Contrast this to 1995, which saw ten in a 35-day span, or one every 3.5 days.)

--Also since 8/22, only one day--September 5th--had no named storms. Average daily ACE over that period has been 2.7474.

--2010 has now seen more named September storms than '95, '96, '97, '99, and '09, and it's seen as many as '01, '03, '04, '06, and '08.

--To-date, HDP (Hurricane Destruction Potential) stands at 54.1275.
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Quoting TropicalAnalystwx13:


What was your other handle?


LPStormspotter... had the yellow race car as the avatar
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They're beautiful when they are out at sea, but they begin to lose that beauty as they come closer to land. I hope Igor remains beautiful.
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That, if verified by an official advisory, would make Igor the 51st most intense hurricane in history, just behind Lenny of 1999.

That means there are now 3 hurricanes from this year alone in the top 100 or so list.
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AL, 12, 2010091312, , BEST, 0, 146N, 256W, 35, 1004, TS, 34, NEQ, 45, 45, 45, 60,
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good morning, nhc goofed on Igor's coordinates in the 8 a.m. update:
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT MON SEP 13 2010

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF
SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE
EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE
IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND
RADAR.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1045 UTC.

...SPECIAL FEATURES...

THE CENTER OF HURRICANE IGOR AT 13/0900 UTC IS NEAR 17.7N 44.4W.
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AL, 11, 2010091312, , BEST, 0, 176N, 492W, 130, 933, HU, 64, NEQ, 40, 35, 30, 40, 1010, 300, 20, 0, 0, L, 0, , 0, 0, IGOR, D,
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Quoting cat5hurricane:
That is some piece of work. Beautiful. Not gonna lie.



Kinda looks like Sonic the Hedge Hog
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Quoting LPstormspotter2:


Created a new account


What was your other handle?
Member Since: July 6, 2010 Posts: 113 Comments: 32830
What a beautiful monster.

""
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4022. bird72
Storm W, the high in 35n and 70w, will be an important factor in the path of Igor?
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Hurricane Igor Update Sept. 13th. 2010
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I think Igor has finished his intensification.

For now.
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is Igor moving just South due West?
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Quoting StormW:


You're kidding, right?


Good Morning Storm!!!
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Quoting earthlydragonfly:


Recon is there right now??? I am in the air over Tallahassee... Cant see it from here.. LOL
URNT15 KWBC 131213
NOAA2 WXWXA 92L3 HDOB 18 20100913
120330 1920N 07415W 5259 05503 0304 -014 -080 140021 021 018 001 00
120400 1918N 07416W 5259 05503 0304 -013 -081 141020 020 018 000 00
120430 1916N 07418W 5259 05505 0304 -010 -132 142020 020 019 000 00
120500 1915N 07420W 5259 05504 0305 -011 -117 143021 023 019 000 00
120530 1913N 07422W 5259 05505 0305 -013 -071 139021 022 021 000 00
120600 1911N 07424W 5260 05503 0304 -011 -122 144020 020 021 000 00
120630 1910N 07426W 5260 05502 0303 -014 -120 140020 021 022 000 00
120700 1908N 07428W 5259 05504 0303 -012 -113 138020 021 022 001 00
120730 1906N 07430W 5260 05502 0304 -015 -105 143019 019 022 000 00
120800 1905N 07432W 5259 05503 0304 -016 -107 136019 019 021 000 00
120830 1903N 07434W 5259 05503 0303 -018 -085 136020 021 021 001 00
120900 1901N 07436W 5259 05503 0302 -018 -091 137020 021 020 000 00
120930 1900N 07438W 5260 05500 0302 -018 -101 133020 021 020 000 00
121000 1858N 07440W 5260 05502 0302 -019 -089 137020 020 020 000 00
121030 1857N 07442W 5259 05500 0302 -020 -071 136020 020 019 000 00
121100 1855N 07444W 5259 05503 0302 -020 -066 137020 021 018 000 00
121130 1853N 07446W 5260 05500 0302 -020 -064 137021 022 015 000 00
121200 1852N 07448W 5260 05500 0302 -018 -062 137020 021 014 000 00
121230 1850N 07450W 5261 05499 0302 -015 -064 138019 019 015 000 00
121300 1848N 07452W 5260 05502 0303 -017 -061 140021 022 013 000 00

Member Since: October 9, 2008 Posts: 0 Comments: 8436
Good Morning. While the US will probably be at risk in late-September and October from more "local" storms spinning up from frontal remnants, I am glad to see, per the current model runs, that our current batch of CV storms appear to be fish-storms for the moment.....A potential season where the most powerful CV storms that form go out to sea is a good thing folks.
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I'm thinkin' Igor watched the Falcons-Steelers game yesterday.

He predicted the scores pretty well until overtime.
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Quoting StormW:


I'm not saying he definitely won't turn, but I think it will occur later.

Oh ok, just wanted to know if I was reading the chart correctly.
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Quoting stormwatcherCI:
Also, first time seeing black in the AVN. If I am reading recon right pressure n the area is at 1005 mb.


Recon is there right now??? I am in the air over Tallahassee... Cant see it from here.. LOL
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Quoting robert88:
So when is this big pattern change supposed to happen and keeps storms moving more W?


And why would you want that to happen? You know I do look at hurricanes in awe and I think it is a thrill to prepare and experience them, but the truth of the matter is that after I experience the full wrath of hurricane Katrina I decided that to me it is better to see them from far and see them recurving. I have my parents living in Puerto Rico my father with a heart condition. Believe me when I tell you if there is one thing I am asking God right now is for Igor to recurve north ASAP. Not to mention what would happen if that monster passes just south of PR and then just south of Hispaniola? Haiti which is devastated as it is right now would have another huge death toll including children. No I do not hope for pattern change and I am happy that so far there is something different this year that is causing Caribean storms to dissapear. This is not the norm and my fear is that before the season is over we will run out of luck.
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Quoting Jeff9641:


Whoever said that is wrong as more troughs are predicted and stronger as well. FL could be in trouble as the GFS is indicating a powerful hurricane in the Gulf at the end of the month and anyone of these troughs could shoot any system in the Gulf NE. It really looks as the real peak for this year may still be coming. The wave on Africa is the one that the GFS sends into the Caribbean I think.


The majority of people on here said it was coming and we would see development further W as well. This came out of the mouths of the ones that most people on this forum look up to so much. Just wondering what happened???
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Repost:

I dont know about anyone else but the appearance of the disturbance in the carib (invest 92) is putting together a classic S feature. Normally when I see this happen the Depression is about to develop. and convection seems to be on the rise... Any other thoughts on the carib developing (92)????
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Quoting earthlydragonfly:
I dont know about anyone else but the appearance of the disturbance in the carib (invest 92) is putting together a classic S feature. Normally when I see this happen the Depression is about to develop. and convection seems to be on the rise... Any other thoughts on the carib developing (92)????
Also, first time seeing black in the AVN. If I am reading recon right pressure n the area is at 1005 mb.
Member Since: October 9, 2008 Posts: 0 Comments: 8436
Quoting LightningCharmer:
Are You still using the old computer or the new one? How are you posting here now?


Created a new account
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Quoting lickitysplit:
Seems to me that Igor's westerly path has ceased and he's now making a slight turn to the north. I see a sharp westerly turn again tho in just a few days as that coming high blocks him in. There is a strong chance for a new england hit.


I see a wobble, no definite pull to the north as of yet....
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Quoting StormW:


I'll try to do a graphic once I finish my synopsis. Basically, what I'm saying is...I believe he will be further west than indicated before he makes a "good" turn


Like his Cape Verde-hurricane predecessors this year, essentially.
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Quoting LightningCharmer:
Are You still using the old computer or the new one? How are you posting here now?


New One
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4001. DDR
Quoting AstroHurricane001:


GFS consistently predicted (for 36 hours) a hurricane in the Gulf or one moving from the Caribbean toward the East Coast by the end of the run. This time it shows two components.


The gfs has also been persistent in showing a large area of disturbed weather over the island by weeks end,things could get intersting here once again!.
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I dont know about anyone else but the appearance of the disturbance in the carib (invest 92) is putting together a classic S feature. Normally when I see this happen the Depression is about to develop. and convection seems to be on the rise... Any other thoughts on the carib developing (92)????
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3998. bassis
Morning storm, levi, kori and all

Igor looks mighty hansom this morning, any idea if it went through ewrc last night
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Quoting Jeff9641:


Whoever said that is wrong as more troughs are predicted and stronger as well. FL could be in trouble as the GFS is indicating a powerful hurricane in the Gulf at the end of the month and anyone of these troughs could shoot any system in the Gulf NE. It really looks as the real peak for this year may still be coming. The wave on Africa is the one that the GFS sends into the Caribbean I think.

Jeef were expected to have NE winds here for the rest of the week and in to next week. Also lower than normal rain chances. I do see a weak trough swinging by the Northeast later in the week as winds shift to the SW, but even that and all washes out as NYC is only predicting a 30% chance of rain. I got my forecasts through wunderground and TWC.
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Quoting StormW:


I'll try to do a graphic once I finish my synopsis. Basically, what I'm saying is...I believe he will be further west than indicated before he makes a "good" turn


Thanks in advance. The setup is interesting...
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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.

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