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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TS BUSTED FORECAST ALIBI
I'm not sure. Levi spoke about this on his blog/video better than I could explain it. And yes the gulf is hot. It's scary having anything that could develop in the gulf or Caribbean because like you said it wouldn't take long.
Almost forgot. The 2.8 is also a huge plus for me on that lens. With that aperture setting, I wouldn't have to go with the much more costly IS version.
And to make sure we stay on topic...Here's Igor
Is it a square?
Is it a rectangle?
or an equilateral...
oops, wrong shape
If he becomes large enough, and with very large outflow, they can influence the environment around them. We saw this with hurricane Gilbert back in 1988, and perhaps Tip in 1979 in the Pacific. They still tend to follow the hills and valleys, in terms of direction, however. How those hills and valleys are changed by the outflow of a very large system, can be trickier than forecasters like to admit sometimes.
I have a question....is that a BIG ridge that is protecting SETEX and Louisiana? Doesn't it block anything that comes up this way??? TIA :)
Ok. Thanks. Hadn't read that one yet. Hope it does hold firm. :)
Is it just me, or did Igor just shed a bunch of his convection?
For now, it should protect us.
I suspect he's feeling the wake of Earl, but it's just a guess.
Keep in mind, there are people who post in this blog who have a deep background in weather. Not all of them, but you'd be surprised how many. Their expertise in weather may not always be associated with hurricanes directly, but they may understand much more than you realize how the enviornment effects hurricane stearing, intensity and evolution. I have seen former and present meteorolgists, former NHC employees and even former Hurricane Hunters post in these blogs. I agree not every poster has that kind of background, but there might be more credible posters here than you realize.
Evening Joanie. :) That ridge will protect us if it does weaken or move at the wrong time.
We think he might be starting an EWRC
Nope:
Hi KoritheMan:) Thanks for your answer...do you know for how long that ridge is suppose to be there?
Then again, it could be a form of strengthening by becoming a more compact storm...
Btw, where is the weakness there? I don't really see one, or am I missing it?
Hi there :) Let's hope not!
Yeah I usually do. Went right past that one to Brownsville today. Running late still. I might catch up by their next discussions. :)
Thanks...and great points...I just wish I had a "Who's Who in the Zoo" so I could know who to pay attention to..as opposed to who is blownwg smoke and wish casting!
In general, it should remain in this area for at least the next week. Some fronts will try and push it eastward a tad, but all in all, not too much.
Thanks a bunch! I sure hope we don't get any hurricanes this year in SWLA ...:/
Indeed. All 3 models show IGOR moving North at some point...but to a point. The GFS is showing a weakness between the two ridges, but then the ridges filling in...albeit not as strong as the NOGAPS. The NOGAPS on the 00z run shows IGOR turning back to the West after it gets to around 27N. My point was why? Why did it shift? The ridge looks like the answer. Have a look:
Well spoken..IMO
African Continent Very Robust
Don't forget GFS has a cold bias that always overplays the strength of trofs as well.
Wow!!!
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