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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Nope, still seems to be straight on 270.
C
now you made me sad
LOl!
I don't normally do polls but...
How strong will Igor be at 5 p.m.?
A. 160 mph.
B. 155 mph.
C. 150 mph.
B. And going almost straight west for the next 36 hours.
I'd say he's grown quite a bit!
The current steering map from CIMSS does not let him go north from 200-700MB ridging as pointed out on the map posted by PR.
SO
Either all the models are wrong
The steering MAP is wrong or Igor will take the low level weakness and go north anyway.
Looking at the upper level maps
http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/carib/gfs/12/model_lu.shtml
I don't see where CIMSS is getting that ridge or at least it is supposed to be gone in 12 hours.
Here is a link to the paper on Hurricane Gloria:
http://www.gfdl.noaa.gov/bibliography/related_files/yk9501.pdf?PHPSESSID=bca7ef556d5bfeab852e8fa2dc 54efeb
One of my favorites on hurricane-environment interaction.
EDIT: Merrill's paper: http://www.aos.wisc.edu/~aos718/environmental%20interaction/merrill.pdf
Don't forget the beer!!!
Well that explains it....the little blue pill strikes again.
NW turn? Where?
That reminds me of 1969. lol
Can't see anything there that's even dreaming of spinning.
correct the troughs will have to cause a weakness for him to go through
Yeah...where? We are in denial...:)
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.
JeffMasters prediction.....
What you basically just said is at least one of the two major forecasting tools is wrong...
http://ecocentric.blogs.time.com/2010/09/13/oceans-resetting-the-ocean-conveyor-belt/
He might be the most beautiful hurricane I've ever seen.
got it storm thanks for explaining this as always good call .
Hope you all find it a good read!
got it storm thanks for explaining this as always good call .
got it storm thanks for explaining this as always good call .
Thanks got it.
btw - Igor is slowing down. Definitely going to fall short of the next forecast point. I think a turn is eminent.
If the flow is more zonal, what does that mean regarding the direction of Igor? (learning) Thx - :)
ok so whether or not he misses the trough does not matter as long as the trough causes the weakness to attract him? Right? Thanks for your answers.
ok so whether or not he misses the trough does not matter as long as the trough causes the weakness to attract him? Right? Thanks for your answers.
Next hours critical....
Or an EWRC is imminent. We saw that with Earl. He slowed down when he changed clothes.
Location: 17.5°N 49.7°W
Max sustained: 150 mph
Moving: W at 10 mph
Min pressure: 933 mb
...........................................
...IGOR CONTINUES WESTWARD...EXPECTED TO TURN TOWARD THE WEST-NORTHWEST TONIGHT...
5:00 PM AST Mon Sep 13
Location: 17.7°N 50.5°W
Max sustained: 150 mph
Moving: W at 10 mph
Min pressure: 933 mb
Well
Look at all the models..
Look at the CIMSS steering chart.
If like me you see that 700-200MB ridge on the CIMSS chart north of Igor and it's going to stay there and you think Igor will not go through it then what?
For those who need some help on the difference in zonal and meridional flow
Link
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