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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With Earl, NHC had him moving more to the WNW and NW well before reaching the Islands, but instead it was after the islands that that turn started.
I saw you response. What you quoted from me was my response.
I have the same problem. The steering doesn't show a route to the NW.
You mean in the Atlantic Ocean and north of the Leeward Islands right? Because ever in the Atlantic you miss Rita, Katrina and Wilma.
B
Should be A
The trough passing over him now is only going to leave a weakness to allow him to go northwards..it was never forecast to pick him up and fully re-curve him. You can see on the Sat loops that the trough and Igor are just passing each other with the trough creating a weakness.
Now we have to see if ALL the models are correct and Igor moves into it. If not it will be due to mid upper level ridging as you seem to hope Storm. You do know what you are talking about and there is about a 1 to maybe 5% chance it will happen.
I'll share some I have at the office if you don't mind "lite" lol
Cybr, I agree. Julia is becoming more and more impressive by the frame.
92L is still disorganized, but a developing surface circulation is present.
I know there will be a collective sigh of relief when he does make the turn!
popcorn and coffee?? Yuck!
I respectfully disagree. How do you account for the secondary maximum in return strength on the 85GHz pass?
Then again, it is entirely possible that I am hyper-analyzing the pass. But until I can find further evidence against it, I'm going to stand by what I see.
URRICANE IGOR AND COMPANY SYNO... - Wunder Blog : Weather Underground
Sep 13, 2010 ... Igor, being a strong Category 4 hurricane, close to Category 5, is also pumping the ridge, allowing it to extend just a little further west, ...
deutsch.wunderground.com/blog/StormW/comment.html?entrynum=776
IMHO I see no indication, in the above WV loop, that Igor will feel the effect of any weakness from the north, and begin turning in the near future (12 to 24 hours). However that may change after 36 hours....
Pretty please? :0)
My Answer is (B)
Doesn't look good. The ridge appears to be building stronger IMO...
Link
That was my point sailing. The first trough is NOT "moot". It is what is scheduled to start Igor's bend to the NW. I believe it will. Just saying that hedging your bets with that 1-5% chance for three storm pretty close together does not seem like responsible forecasting. It's like deciding to bet slots instead of playing Black or Red in roulette. Your odds are much worse with the slots.
*sigh* See? This is why you should always just watch a hurricane before you try and predict movement off 15 mins of motion
I hear ya; I can't give you a scientific explantion but I am much more worried about the East Coast or Bermuda from this one than with Earl; just a gut feeling that he might be headed for a landfall somewhere as he nears 30 N once the models catch up with him around that position....I hope that is not the case.
You have no idea!!!!I'll need a few boxes myself, please, tia!
Given the heat content there, assuming the system gets a good LLC going and atmospheric conditions are favourable for development, that seems a pretty good assumption.
yeah i dont know why people keep saying that nhc had earl pegged when three days before earl passed just 100 miles north of PR they said earl was going to pass over 500 miles north of us so yeah excuse me if i keep my eyes open an dont take the models as face value
NOAA maybe but HH cant fly that far out
Igor, look at the shadows in his eye, simply an amazing cyclone to watch today and tonight and throughout his lifespan so far. I mean just a few days ago we were worrying about him intensifying at all. Simply amazing structure and I am not surprised the first trough completely missed him and the second trough will not pick him up completely and ridging will build in again to his northeast and will steer to the WNW south of Bermuda. This is getting bad for that island.
Nope, still seems to be straight on 270.
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