92L still a threat to develop; Igor a hurricane; TD 12 forming near Africa
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
Reader Comments
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That image looks so cool!
http://tropicalatlantic.com/recon/
Kinda like what Opal did in 1995..
Wow....IGOR IS MONSTER!!!
Thanks man! Igor's certainly a beast. I admit, he even surprised me. Which is rare.
Hello Levi i see the jog to the South too ,we are in PR and i begin feeling nervous do you think we are not save yet?
Perfect eye.
Might be stronger than 150 mph...
I didn't know EARTH had a GREAT RED SPOT on it! I'll bet JUPITER is envious tonight!
Weak wind shear from the south or southeast...a cold east wind at the 200 mbar level...SSTs no greater than 28.5C. Rut roh!
First trough won't do much to him. I think he will be south of the NHC/model forecast at Days 4 and 5. I still think recurvature east of the US is most likely but there is enough variance in the pattern for me to be worried that he tries to come back all the way to the SE US coast. It's still the outlier solution at this point, but it can't be dismissed.
Link
If it's going to do so, it needs to do so before it runs into the Yucatan. I'm starting to have my doubts, but I still think it has a decent chance.
Igor will likely be the single greatest ACE contributer to the 2010 Atlantic hurricane season.
We're only half-way there.
I think it's pretty unlikely that you'd get a direct hit, but there's a chance he passes by close enough to the north that you get the outskirts of the system. Be ready for that possibility, but we'll know more when he's approaching 60W.
And we are just slightly a little more then halfway through the season...plenty of time for 7-12 more storms.
Ah! Thanks for pointing this out - been looking for a storm that started over Africa all day. Here's Christine:
http://www.wunderground.com/data/dhc_archive_charts/at_1973_charts/at197304.gif
I think yhis is one of the latest satellite photo. Can anyone tell me where is the center?
Agreed!
Trough was weakening when it went through my house in New York today..hardly even rained..
africa wave beats 92l and is julia
92l trying to hold
new blob by the bahamas ?
whats next
Levi, I'm listening to Storm and he has the same concerns. He's favoring the south tracks at this point and is concerned about that second high without a trof to pull Igor north.
If you look at the water vapor imagery out ahead of the storm you can see that the mid to upper level flow is coming down from northeast which may be why it is taking that jog south of due west.
Igor is living up to his name...
Yeah but we probably won't get another opportunity for a storm to develop right off of Africa, literally right off, and then become a major rather fast and take a long track all the way across the Atlantic and make a sweeping recurve. That racks up the most ACE points you can ask for in the Atlantic, and Cape Verde season will be winding down soon.
The only reason it isn't a Category 5 is because we don't have any reliable data other than ADT, which says its at 150 mph. If there was and it was saying it is a Category 5, it would be one. Simple.
Plus, storms this compact and intense rarely go through EWRC's.
also, if not, why do during the life of the systems recently a lot of the models runs show this for a couple runs but back off of it and it never happens.
also, what are the chances of a high building in and having igor hit florida?
Where are you listening to the Chief??....Is the BB show on??
000
NOUS42 KNHC 111530
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1130 AM EDT SAT 11 SEPTEMBER 2010
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 12/1100Z TO 13/1100Z SEPTEMBER 2010
TCPOD NUMBER.....10-103
I. ATLANTIC REQUIREMENTS
1. SUSPECT AREA (CENTRAL CARIBBEAN)
FLIGHT ONE -- TEAL 70
A. 12/1800Z
B. AFXXX 01EEA INVEST
C. 12/1145Z
D. 15.5N 70.0W
E. 12/1700Z TO 12/2100Z
F. SFC TO 10,000 FT
FLIGHT TWO -- TEAL 71
A. 13/0600,1200Z
B. AFXXX 0212A CYCLONE
C. 13/0400Z
D. 16.2N 74.4W
E. 13/0500Z TO 13/1200Z
F. SFC TO 15,000 FT
2. SUCCEEDING DAY OUTLOOK: CONTINUE 6-HRLY FIXES IF
SYSTEM DEVELOPS.
3. REMARKS: SEVERAL RESEARCH FLIGHTS ARE PLANNED
FOR THE CENTRAL CARIBBEAN SUSPECT AREA.
A. THE NSF/NCAR G-V WILL FLY A 7 HR MISSION BETWEEN
41,000 AND 43,000 FT WITH TAKEOFF AT 12/1100Z.
B. THE NASA GLOBAL HAWK WILL FLY A 24 HR MISSION
ABOVE 58,000 FT WITH TAKEOFF AT 12/1130Z.
C. THE NOAA G-IV WILL FLY AN 8 HR MISSION BETWEEN
41,000 AND 45,000 FT WITH TAKEOFF AT 12/1730Z.
D. THE NASA DC-8 WILL FLY AN 8 HR MISSION BETWEEN
35,000 AND 39,000 FT WITH TAKEOFF AT 12/1800Z.
E. NOAA 43 AND 42 P-3 AIRCRAFT WILL BEGIN A SERIES
OF MISSIONS BETWEEN 7,000 AND 12,000 FT WITH
TAKEOFFS AT 12/2000Z AND 13/0800Z...RESPECTIVELY.
Yeah. It's good.
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