Igor an impressive Cat 4; 92L running out of time to develop; Julia forms
There are few sights in the natural world more impressive than a hurricane near maximum intensity. Hurricane Igor certainly fits that description this morning, as it flirts with Category 5 strength in the Central Atlantic. Igor's rapid intensification burst brought the mighty hurricane's winds to 150 mph, just shy of the 156 mph threshold for Category 5 status. Igor is the strongest hurricane in the Atlantic in three years. The last hurricane stronger that Igor was Category 5 Hurricane Felix of 2007.
Figure 1. Morning satellite image of Igor.
Intensity forecast for Igor
Wind shear is low, 5 - 10 knots, and is expected to remain low for the next four days. Waters are warm, 28.5°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. These conditions should allow Igor to remain at major hurricane status for the next four days. The hurricane will probably undergo one of the usual eyewall replacement cycles intense hurricanes commonly have, where the eyewall collapses and a new eyewall forms from an outer spiral band. This will weaken the hurricane by 10 - 20 mph when it occurs, but Igor will probably regain its lost intensity when the cycle completes. There's no evidence that an eyewall replacement cycle is imminent today, so Igor could potentially strengthen a bit more. However, I believe Igor has peaked, and will not reach Category 5 status today. By Saturday, when Igor should be nearing Bermuda, the trough of low pressure steering Igor northwestwards should bring moderate wind shear of 10 - 20 knots to the storm, weakening it.
Track forecast for Igor
The track forecast for Igor remains unchanged. Igor will move west under the influence of a strong ridge of high pressure until Tuesday morning, 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 appears likely to be a threat to Bermuda, and that island can expect tropical storm force winds as early as Friday. Igor 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 - 10 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 hitting the U.S. or Canada. While the trough expected to recurve Igor out to sea is not as sharp as the troughs that recurved Danielle, Earl, and Fiona, it should still be strong enough to keep Igor from hitting the U.S. However, Newfoundland, Canada could see a close pass. An examination of the tracks of the ten major September hurricanes that have passed closest to Igor's current location (Figure 2) reveals that one of these hurricanes went on to hit the Bahamas and Florida as a Category 2 storm, and another hit Newfoundland as a Category 1 storm. The other eight missed land. One wild card may be the intensification of Julia behind Igor. If Julia develops into a hurricane and moves close to Igor, as some of the models are suggesting, the two hurricanes could interact, affecting the track of Igor unpredictable ways. However, it currently appears the Julia will be much weaker than Igor, and will probably have little impact on her big brother's track.
Figure 2. Historical plot of the tracks of the ten major September hurricanes that have passed closest to Igor's current location.
Caribbean disturbance 92L
Tropical disturbance (92L) over the Central Caribbean, centered about 100 miles south of Jamaica, has changed little over the past day. The storm remains a threat to develop into a tropical depression, but time is running out for it to do so. Satellite loops this morning do not show a surface circulation, but 92L does have a moderate area of intense disorganized thunderstorms that are bringing heavy rain to Jamaica this morning. Kingston, Jamaica has picked up 0.67" of rain thus far this morning from 92L.
Figure 3. Morning satellite image of 92L.
Forecast for 92L
Wind shear over 92L is low, 5 - 10 knots, and is expected to remain low to moderate for the next five days. The waters beneath are hot, 29.8°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 has been interfering with development of 92L. NHC is putting the odds of 92L developing into a tropical depression by Wednesday at 40%. Given the current disorganized state of 92L, it would be difficult for it to intensify quickly enough to become any stronger than a tropical storm with 50 mph winds by Wednesday, when it will move over Belize and Mexico's Yucatan Peninsula. 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 several hundred miles south of the Texas border. A Hurricane Hunter aircraft is scheduled to investigate 92L this afternoon.
Julia
Tropical Storm Julia formed between the Cape Verdes Islands and coast of Africa yesterday, bringing some heavy rain squalls and gusty winds to the Cape Verdes, but no sustained winds of tropical storm force. Julia is headed northwest, out to sea, and it is unlikely that this storm will trouble any land areas . Shear is low enough over the next few days to allow Julia to become a hurricane, but shear will rise sharply 4 - 5 days from now, limiting the potential for Julia to become a major hurricane.
Elsewhere in the tropics
The NOGAPS model is calling for a new tropical depression to form off the coast of Africa 6 - 7 days from now.
Next post
I'll have a new post Tuesday morning.
Jeff Masters
Reader Comments
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Human bias, some want to feel danger, some want to feel safe. Some like the rush of a chance at landfall, others like to feel secure that they are safe.
Interesting, maybe it's just because I'm an amateur, but the ridge pumping idea makes intuitive sense to me, much like the frictional effect on track (as in Hermine).
Was wondering that myself. But it looks more west now on that shot. But what do I know. :)
Thanks for providing this to us, StormW.
From the looks of it now, there's a little hill in front of Igor. Is he expected to climb it, or will it simply disappear by a flattening trough to the north? Isn't this little hill, why we've seen Igor dip to the west southwest, briefly ... perhaps. Just asking ...
Check out post 1394. That's my take.
I will say this. If we wake up tomorrow morning and this cyclone isn't past 18N there's gonna' have to be an emergency airlift of DEPENDS to Puerto Rico.
Still looking for a reason for him to cut himself off from the weakness left by the troughs I see. Well the next 12 hours will tell..
I see no evidence that an EWRC is taking place
AL, 12, 2010091318, , BEST, 0, 151N, 269W, 45, 1000, TS
Looking at steering... really, how is he supposed to turn?
I never said you don't have any idea what you are talking about...Rather you have no idea "how" to talk about it.
And if I'm not mistaken, the first trough is what is supposed to be about to turn him correct? I didn't think a second trough was even in the picture yet? On top of that, it's not the trough that will turn him, but the weakness created by the trough that will allow him to turn.
Well AM worrying about here in Beize...
Please send a few hundred Cases to the VI's first..
OK here I go ..PITA..go get the boat ready to leave on a 60 mile trip by midnight if Igor isn't turning. Sail through the night. Spend Tomorrow in the Mangroves swamps in Jobos as Igor will wipe Culebra clean if he does not turn and does a Georges track. Then watch him re-curve last minute and have a 60 mile dead upwind sail back..
I disagree. I don't like to use the weak 85GHz because it seems to amplify the return intensities too much, resulting in lack of detail. the Standard 85GHz microwave pass shows much more detail, and it appears that a more subtle and low-profile ERC is taking place, similar to some of the ones that Dean went through in 2007. That would account for the warming of the cloud tops, especially those directly adjacent to the eye, as well as the slight enlarging of the eye seen over the past few hours (the latest pass is 3.5 hours old).
As with Earl, I think the models and NHC have a pretty good handle on the short-term track (forget the 5 day track and stick with the 3-day) so not losing sleep yet over the Greater Antilles. If you look at the Lat, it should be about even with PR and slighly North of them by tommorow afternoon......I would give it until 5:00 before you ship out those supplies.... :)
Shucks...keep forgettin the popcorn.
When Storm says things like this, I start to worry...b/c clearly StormW knows WAY more about hurricanes than I could ever hope to...Storm, please help keep us informed no matter how frustrated you get...we luv ya! :)
92L is trying to get a definable surface low, but convection is really disorganized. I don't expect a TD until tomorrow as he clears the proximity to Jamaica.
How strong will Igor be at 5 p.m.?
A. 160 mph.
B. 155 mph.
C. 150 mph.
Still a due west track with little wobble involved...the actual "turn" won't happen for a while yet.
Anyone care to call me a westcaster? I have no problem with it, as long as you know that will require the name caller and me in the blood box...
LMAO
weakening convection around the eyewall is not the same as an eyewall replacement cycle
there is no evidence of an EWRC taking place
C
That little "pimple" in the SW quadrant seems to have a spin. Would that be a tornado?
So if that is the case, then you are saying the Islands are in serious trouble because there is no way that the second trough was sitting right on to p of the first one which would mean that he will not turn in the next 24hrs?
Just seeing this - appreciate you taking a go at answering this for me. :)
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