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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What is a T5.5 mean in terms of intensity? haven't memorized the Dvorak scale.
I still say we have to wait and see. Lots of different scenarios could play out based on minor changes in the synoptic pattern. But PR is not yet totally out of the picture.
And it was DEEELISHUS too.
The amount of calories packed in there, I am sure it's a sin....
We are watching an Incredible Igor, right now.
Or if the Low in the Surface analysis forms and it shifts right
I know! If Igor pulls off cat. 4 by 5 PM, Igor would have been one of the biggest rapid intensification episodes on record, but not supreme to Wilma. Wilma went from tropical storm to cat. 5 in about 24 hours, Igor would have gone from tropical storm to cat. 4 in 24 hours if this proves true.
IF Igor is a rare annular hurricane, he will NOT have any Eyewall relacement cycles..This makes him super dangerous, as he may create his own steering currents and be very slow to weaken.
IF Igor is not an annular, his wind fields will become much, much larger during an EWRC!!
Scary Thought
AL, 12, 2010091218, , BEST, 0, 131N, 223W, 30, 1006, TD, 0, , 0, 0, 0, 0,
Are you talking about the big Low shown in the computer model runs east of Igor? That Low would be Julia, the future of TD 12. Julia would make this situation worse if anything, because both Igor and Julia would pull a Fujiwhara interaction with each other, sending Igor's tendency further south and west and Julia's tendency further north and east.
PS: Igor is at about 125 knots (ADT estimates) over water that is just over 28 degrees (see WU and CIMSS SST map). He is predicted to track over water at least a full degree warmer once he reaches 55W. I can easily see this topping out as a 920mb 140 knot Category 5.
Hi Storm, can't help but think that high (over TX) is going to break eventually.....just can't imagine it protecting us the whole season.
I have pizza, wine, Patriots on TV and winning and tropical chatter on the weather underground. Life is good.
So a trough would guide him but a ridge would block him?
I heard its raining in Freeport
Okay, so we have a cat. 3 on our hands then at least conserivatvely. Not surprising.
True, annular hurricanes are scary, or very large hurricanes(Tip style), they can do the same thing.
That thing doesn't look right.
Torrential rain with NorthWest winds right now....
NW winds are the only ones that blow rain into this house through vent-blocks and fretwork....
It's becoming moist in here.......
100% Agree! He was the first person I discovered on this blog that was so knowledgeable and so willing to help us weather-geeks and just so fricken' nice. I have learned a heckuva lot from him over the years. StormW Rocks!
LOL see my last post.
a CAT 5 needs to be in near perfect conditions at the minimum
Viewing: 951 - 1001
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