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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I would think its more of an amphibious term lol
Based on this, Igor continues to undergo rapid intensification.
Category 4 Igor Satellite Loop
LOL.
Amen. I'm counting the Opal days(Oct. 4th).
He is still on line from the forecast three days ago.
Thanks for the compliment!
yep, the anticylone is centered right over it too, perfect conditions for rapid development
nope been mostly right on the points today
The eyewall is cooling about 1 degree an hour on average and the eye is warming about the same right now. This has to stop soon though, as Igor can only get so strong over 28 degree water. If upper level conditions remain nearly perfect like they are now then Igor should very slowly strengthen as the waters underneath warm, then begin to slowly decay once he crosses 25 North.
I think the magic Number is +20/-75, if ADT records that then we have a cat 5.
Unfortunately it is becoming a forum of "I'm right and you're wrong and if you disagree you're an idiot."
Wait a minute...If a moderate Cat4 is undergoing RI, shouldn't it be a Cat5 by 11?
Exactly, it would be nice if some would follow the lead of people like Drak, Levi, StormW and Kman. They don't always agree, but when they disagree with each other they do it the right way.
And never suggest the possibility of landfall, or that people should be prepared for it.
You forgot about mentioning the trials of downcasters.
Clips(CLP5), model could tell you.....Link
You aren't poking your chest out like a bannie rooster are ya? lol joke
Igor is not undergoing RI anymore winds wise, the organization suggests about 10 knots per 6 hours of strengthening. To me RI starts at 15. For a hurricane of Igor's strength though intensification after Category 4 is rare.
Pressure wise Igor is probably deepening at about 2-3mb an hour, near the line. At the rate it's going it would be a Cat 5 by 5am, however I doubt that Igor will continue to strengthen that far this early. The water temps do not support it.
With a pinhead eye!
Nope...not me. Man has to know his limitations.
we all doom!
confusing?
Hopefully, he'll reach Cat5 status for 2 advisories or so and gradually weaken by the time he reaches any landmass.
because :)
I wonder if the Caribbean storm GFS has been developing in two weeks is in the picture yet.
I don't think the water is the main issue, I think the upper air conditions wont allow it
Only the last day or so of forecasts have been within the cone.
NHC Forecast Error for Igor
yea the Slower part is what is bothersome
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