Potentially dangerous 92L steadily developing; Igor nears hurricane strength

By: Dr. Jeff Masters , 3:04 PM GMT on September 11, 2010

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A tropical disturbance (92L) over the Eastern Caribbean, a few hundred miles south of Puerto Rico, is steadily organizing and appears likely to develop into a tropical depression by tonight or Sunday morning. Satellite loops show an impressive and expanding region of heavy thunderstorms, with good spiral banding and respectable upper-level outflow on all sides. Long range radar out of Puerto Rico shows that heavy rains are now affecting that island, but there is no rotation to the radar echoes evident. However, the rain bands are becoming more intense and more organized. San Juan, Puerto Rico reported a heavy rain squall at 8:44 am this morning, and radar estimates suggest two inches of rain fell in this squall just southeast of San Juan. Wind shear over 92L is low, 5 - 10 knots. The waters beneath are at near-record warmth, 30°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-northwest at 11 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 Mexico's Yucatan Peninsula on Wednesday. The HWRF model has a more northwesterly track, taking 92L over the Dominican Republic, Haiti, and Cuba, but this model has been trending too far north in its tracks. I expect 92L will follow a path south of the islands, bringing it near or just south of Jamaica on Monday, then into the Yucatan Peninsula on Wednesday. On this track, the southern Dominican Republic can expect heavy rains of 3 - 6 inches tonight through Monday morning; southern Haiti can expect similar rains Sunday through Monday, and Jamaica and the Cayman Islands can expect heavier rains of 4 - 8 inches Monday and Tuesday. Eastern Cuba will probably escape 92L's heaviest rains in this scenario (Figure 2.)

Intensity forecast for 92L
I can't find any reason to doubt this will be a tropical storm by Sunday or Monday, and potentially a Category 1 or 2 hurricane by Wednesday, if 92L avoids passage over Hispaniola and Cuba. The SHIPS model predicts wind shear will remain low, 5 - 10 knots, through the period, and makes 92L a Category 1 hurricane by Monday night. 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. The first Air Force Hurricane Hunter mission into 92L is scheduled for Sunday afternoon, but there will be a research mission by the National Center for Atmospheric Research G-V jet today that will give us valuable information on 92L's large scale environment and potential for development.


Figure 2. Forecast rain amounts from 92L from the 2am EDT Saturday run of the GFDL model. This model predicts most of 92L's heaviest rains will miss Haiti, but will affect Jamaica, the Cayman Islands, and the Yucatan Peninsula. Image credit: Morris Bender, NOAA/GFDL.

Igor
Tropical Storm Igor is very close to hurricane strength, and appears destined to become a large and powerful major hurricane over the Central Atlantic in the days to come. Wind shear is moderate, 15 - 20 knots, waters are warm, 28°C, and Igor has moistened its environment enough to keep the dry air of the Saharan Air Layer (SAL) at bay. Igor will track west under the influence of a strong ridge of high pressure for the next three days, then turn more to the west-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 has a slight chance of making landfall on the U.S. East Coast or Canada. Climatology shows that about 10% 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 5% for Canada. The forecast steering pattern for the coming two weeks from the GFS model 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. The odds of Igor hitting land in the U.S. or Canada are probably close to their climatological 10% and 5% probabilities, respectively.

Elsewhere in the tropics
A new tropical wave (Invest 93L) emerged from the coast of Africa yesterday, and is already showing signs of organization. Most of the models predict 93L will develop into a tropical depression 2 - 4 days from now, and NHC is giving 93L a 30% chance of developing by Monday.

Next post
This may be my only post today; I'll have a new post Sunday morning.

Jeff Masters

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2123. xcool

lol
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Quoting traumaboyy:


slipped and busted your glass??...did I hear that right???


SmileyCentral.com
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2121. xcool
80mph
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Quoting AtHomeInTX:
NOT GOOD



meow...that looks bad!!
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Quoting AtHomeInTX:


Oh sorry. Couldn't find my glasses. I SAID WE'RE GONNA BE OLD AND GRAY. Or did I say that??? Hmmm? Memories slippin. :p


slipped and busted your glass??...did I hear that right???
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UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 12 SEP 2010 Time : 071500 UTC
Lat : 17:43:12 N Lon : 43:29:59 W


CI# /Pressure/ Vmax
4.6 / 978.8mb/ 79.6kt


Final T# Adj T# Raw T#
4.1 4.1 4.0

Latitude bias adjustment to MSLP : +1.6mb

Center Temp : -41.1C Cloud Region Temp : -65.9C

Scene Type : UNIFORM CDO CLOUD REGION

Positioning Method : SPIRAL ANALYSIS

Ocean Basin : ATLANTIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : 0.5T/hour
Weakening Flag : ON
Rapid Dissipation Flag : FLAG
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Quoting traumaboyy:


eh...what's that ya say???


Oh sorry. Couldn't find my glasses. I SAID WE'RE GONNA BE OLD AND GRAY. Or did I say that??? Hmmm? Memories slippin. :p
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NOT GOOD

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Quoting AtHomeInTX:


Lol. Guys we're gonna be old and gray trying to figure out this mess.


eh...what's that ya say???
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2114. xcool
My brain is fried on 92l and this hurricane season,
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2113. xcool
lmaoo
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Quoting btwntx08:
hmmm ok


Lol. Guys we're gonna be old and gray trying to figure out this mess.
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2111. xcool
huh
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2109. xcool




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2108. xcool
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This from Brownsville last night

7 AM MONDAY THROUGH SATURDAY...LIGHT WINDS AND LOW SEAS ARE
FORECAST ALONG THE LOWER TEXAS COAST EARLY IN THE LONG TERM PERIOD
AS HIGH PRESSURE REMAINS CENTERED OVER THE NORTHWEST GULF OF
MEXICO. AS THE HIGH SHIFTS FARTHER EAST...AND A LONG FETCH OF
EASTERLY WINDS DEVELOPS OVER THE ENTIRE GULF OF MEXICO...MARINE
CONDITIONS WILL BECOME MORE UNFAVORABLE ALONG THE LOWER TEXAS
COAST...WITH SEAS BUILDING TO MODERATE LEVELS FOR THURSDAY THROUGH
SATURDAY DUE TO SWELLS FROM THE EAST.
&&

They had the high moving east by Thursday? That could be why the EURO sees 92l just south of there now? Just thinking out loud. :)
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2106. Walshy
Quoting VAbeachhurricanes:


UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 12 SEP 2010 Time : 064500 UTC
Lat : 17:42:53 N Lon : 43:22:09 W


CI# /Pressure/ Vmax
4.6 / 978.7mb/ 79.6kt


Final T# Adj T# Raw T#
4.2 4.1 4.0

Latitude bias adjustment to MSLP : +1.5mb

Center Temp : -46.7C Cloud Region Temp : -66.2C

Scene Type : UNIFORM CDO CLOUD REGION

Positioning Method : SPIRAL ANALYSIS

Ocean Basin : ATLANTIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : 0.5T/hour
Weakening Flag : ON
Rapid Dissipation Flag : OFF



So around 90mph?
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2105. xcool
ATCF: AL, 93, 2010091206, , BEST, 0, 131N, 195W, 30, 1006,
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Well, good night for me too, be back tomorrow.
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Quoting Walshy:
Igor looks stronger than 75mph. Anyone else agree or no?



UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.1
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 12 SEP 2010 Time : 064500 UTC
Lat : 17:42:53 N Lon : 43:22:09 W


CI# /Pressure/ Vmax
4.6 / 978.7mb/ 79.6kt


Final T# Adj T# Raw T#
4.2 4.1 4.0

Latitude bias adjustment to MSLP : +1.5mb

Center Temp : -46.7C Cloud Region Temp : -66.2C

Scene Type : UNIFORM CDO CLOUD REGION

Positioning Method : SPIRAL ANALYSIS

Ocean Basin : ATLANTIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : 0.5T/hour
Weakening Flag : ON
Rapid Dissipation Flag : OFF
Member Since: Posts: Comments:
2102. xcool
ha
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Quoting Walshy:
Igor looks stronger than 75mph. Anyone else agree or no?



Yeah, I am thinking it'll be around 80 mph winds at the 5 AM advisory.
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12z



00z


Looks farther north and stronger to me. Anyway got nothing else to compare it to. Nobody else is showing it. Lol.
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Quoting xcool:


Wow, Igor lookin' better and better. I just had a feeling based on the name that Igor was going to be a strong Cape Verde storm this year, LOL!
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2098. Walshy
Igor looks stronger than 75mph. Anyone else agree or no?

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Quoting btwntx08:
ouch


Holy TCHP!!
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2095. xcool
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Quoting Hurricanes101:
either way, time for bed

night everyone


Night.
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2093. xcool
wow that sst
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Quoting Krycek1984:


Isn't there also the issue of the upwelled, cooler water that is remaining from the track of Danielle and Earl? I would think that would limit intense development, to some degree at least.


Well, if there has been upwelling, its not showing up well on this SST map, here:

http://www.ssd.noaa.gov/goes/east/nwatl/flash-ir4.html

Click on the SST check box during animation. I see a lot of 29 and 30 deg C water south of Bermuda and east of Georgia. That is unusually warm, and I haven't been able to see the cool upwells from both storms, except mabye the 26 deg C spot just east of the NC Outer Banks.

But notice once you get to the latitudes of Bermuda, the water temps drop off, that's why the EURO can't be right with 928 mb at the latitudes of Bermuda. Climatologically, even with these above-avarge warm waters, you're not getting a hurricane in the 920s of mb at the latitudes of Bermuda.
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2090. xcool
lol rob
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either way, time for bed

night everyone
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Quoting KoritheMan:


I didn't know you were referring specifically to CV storms. My bad.


its cool, the person who originally posted was asking about La Nina and the storms re-curving
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Quoting Hurricanes101:


they were not CV storms in 1998

Charley, Earl, Frances and Hermine all formed in the Gulf and Mitch formed in the Caribbean



I didn't know you were referring specifically to CV storms. My bad.
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Quoting KoritheMan:


Add Charley, Earl, Frances, Hermine, and Mitch to the mix as well.


Ahhh, long night..., usually I am on top of my hurricane history. Yeah, who can forget those storms, espeically Mitch!!! aye, how did I forget Mitch too!
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Bed Time nite all......got a long NFL day tomorrow. Then driving 150 miles for an overnite trip to go fishing with my Brother in the GOM on Monday morning. Everyone keep there eyes peeled on 92L and Igor. Will look at everything tomorrow sometime for sure. NITE
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Quoting KoritheMan:


Add Charley, Earl, Frances, Hermine, and Mitch to the mix as well.


they were not CV storms in 1998

Charley, Earl, Frances and Hermine all formed in the Gulf and Mitch formed in the Caribbean

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Quoting NCHurricane2009:
Yep, from the images y'all are posting, that EURO shows Igor recurving between Bermuda and NC, I thinks that is sensible right now. But I disagree with how strong EURO makes Igor at that time. I mean, 928 mb? sheeeesh! That would be one of the strongest hurricanes that far north.


Isn't there also the issue of the upwelled, cooler water that is remaining from the track of Danielle and Earl? I would think that would limit intense development, to some degree at least.
Member Since: August 5, 2010 Posts: 0 Comments: 290
2080. xcool
CoopNTexas 92L need some help
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Quoting NCHurricane2009:
By the way, did you guys see that weird clip from the Weather Channel the other day, State of the 2010 Season, between Jim Cantore, Bryan Norcross, and "Guy from University" (can't remember that guy's name).

Guy from university: A Kelvin wave helped develop Hermine, and then helped to develop Igor. I think we may see more development.

(in background, weather channel shows crappy graphic of a "wave" propagating eastward from Hermine to Igor)

Cantore (cutting off the guy from university after he said that one sentence): Wow, its interesting how those wave interactions help develop those storms (to Brian Norcross), what do you think will happen for the remainder of this season?

Brian Norcross: We are at the peak of the season, and the number of storms we have seen is about what we expected at the beginning of the season...Watching Igor out there.

Cantore: Where do you think Igor will go?

Norcross: I think it will go closer to where Danielle tracked than Earl, but I hate to tell you to keep your eye off of it, its going to be a big hurricane.

Cantore:...hope your prepared, we have a long way to go if we are going to have 18 storms this season, we are only halfway there.

Okay, Weather Channel, why did you let Cantore cut-off that guy that was talking about the Kelvin waves? I wanted to understand that, your crummy graphic didn't help. Why did you even invite that guy if you were only going to have him say one sentence?

And Cantore is a sensationalist, always exaggerating. Norcross is the most sensible guy they've got there, too bad Dr. Lyons left the Weather Channel.


Norcross is the best thing thats happened to TWC in a long time. Wish it were him and Lyons, but Norcross is very knowledgeble. We miss him here in S. FLA
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Quoting Hurricanes101:


ah forgot about Bonnie


Add Charley, Earl, Frances, Hermine, and Mitch to the mix as well.
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We got problems. Here is what is gonna happen. The High in the plains moves in fast and cuts the trough off with a Trough Split then High pressures moves in. Igor is trapped and no place to go but, WEST.

Here is the loop to see.
http://moe.met.fsu.edu/cgi-bin/ngptc2.cgi?time=2010091200&field=Sea+Level+Pressure&hour=Animation
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2075. xcool
JLPR2 yeah thank god :))))
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Quoting NCHurricane2009:


Bonnie didn't go out to sea, it hit eastern NC. I guess that's two storms that didn't stay away from land in 1998.


ah forgot about Bonnie
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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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