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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yea the Slower part is what is bothersome
Hermine caused $150 million
Igor would need to go DUE WEST for 4 days to hit PR. The farthest south it is likely to get is 100 miles NE of the BVI, and even that is unlikely. You need a Dean-Strength ridge to keep a major cane at due west for that long, which we don't have. Igor will turn, the question is when and how sharply.
Ya know, I have always wanted a hurricane for Christmas!
What did I tell ya? We are quite simply doom.
Hey.
The upper air conditions are nearly perfect...Igor is probably within 20mb of the MPI for his area.
General Water Temp/MPI rule:
26.5 degrees = Category 2
27.0 degrees = Category 3
28.0 degrees = Category 4
28.0(High OHC)- 29.0 (Low OHC) = Category 5
Yea, but waves coming off Africa now means they don't arrive near CONUS until the last week of September. Igor may be the last Cape Verde that "semi" makes it across the Atlantic. Trough strength and frequency will continue to increase from here on out.
Interesting that none of them hit Florida or went into the GOM. Period of 158 years.
I agree 100% with this comment
Taco :o)
Earl did $250 million, Hermine did $200 million the last time I checked Wikipedia.
I wonder if those small outbursts are to do with IGOR's rapid intensification
The eyewall is wrapping around, that hole should be filled on the next frame. On a hurricane this strong the clouds move a half circle an image.
========================================
2010SEP12 211500
CI 6.5
937.0
127.0
Initial 6.5
Adjusted 6.7
Raw 6.8
---
geez, 130 knots already.. wasn't this a around 85 this morning. =P
My highest praise to thou holy 'them'. If only all on this board could be them. Common...LOL, have you ever seen someone get slammed for disagreeing with Storm in the morning on this board??
It was a 70 at 5am. At 5pm it was 120. That's 50 knots in 12 hours, with 45 of that in 9 1/2.
92L defiantly is trying to look better, but I don't think recon will find a tropical depression, tonight.
Yeah, seems ready to get going, I believe this is the first time in it's lifetime in which it has built convection at this hour.
Advance Dvorak Technique from the SSD website
Once 2 years ago I actually won an argument with storm, for 10 minutes I had convinced people that I knew what I was doing lol. I haven't been able to repeat that feat though :(
And heading to the ridiculously high TCHP in the NW Caribbean. If it develops a closed circulation by then it may just take off.
Interesting....is there a graphic of the storms that have made landfall in Florida over the past say 5 years that shows also the track from where they started?
They should be.
its a NOOA flight upper air measurements maybe a dropzode
Dont feel bad..Lennon and Mccartney are the most successful composers in popular music history. They cant read or write a note!!
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There are times when the NHC calls for a CONUS landfall from a major hurricane. Are they sure? No, but this forecast is based on the probabilities. And nobody has ever called the NHC "wishcasters".
..
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There is no definite track for any tropical cyclone. But there are definite probabilities. When one over and over takes the underdog, the 1%-5% chance that leads to land...that's the definition of wishcaster.
Where Ike was originally going to land:
Where he ended up:
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