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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If people see a wobble to the south, then its just a wobble and they are seeing things or west-casting.
but if people see a wobble to the north, it is the start of that turn and those who try and say it is just a wobble are again called west-casters.
Pretty funny when you look at it lol
People who live near 17.5N
5%
Not saying it cannot happen, but the likelihood, based on past storms in the same position is poor, indeed.
12Sep . 06pmGMT - - 15.8n72.1w - - 25knots - - 1007mb - - NHC-ATCF
13Sep . 12amGMT - - 15.8n73.8w - - 20knots - - 1007mb - - NHC-ATCF *15.9n73.3w*16.0n73.8w
13Sep . 06amGMT - - 15.8n75.5w - - 20knots - - 1007mb - - NHC-ATCF *16.1n74.7w*16.1n75.5w
13Sep . 12pmGMT - - 15.8n77.2w - - 25knots - - 1006mb - - NHC-ATCF *16.2n77.2w
13Sep . 06pmGMT - - 15.9n78.8w - - 25knots - - 1006mb - - NHC-ATCF
*Before the NHC reevaluated&altered the ATCF numbers.
Copy &paste 15.8n72.1w-15.8n73.8w, 15.8n73.8w-15.8n75.5w, 15.8n75.5w-15.8n77.2w, 15.8n77.2w-15.9n78.8w, pnd, mia, trb, gdt into the GreatCircleMapper for a look at the last 24hours.
Better be careful with that one....LOL
It was really bad in here an hour ago..
I was talking about the models, which you said have been right so far this season, which they have not been. Even the NHC realized those models were folly and kept Earl's forecast path south of the guidance package.
Images last updated: Monday, 13 Sep 2010 16:55:38 GMT
Actually the outflow is building a ridge and giving us the beautiful clear calm before the storm..or maybe that is the mid-upper level high over us
Thanks Drak for this and your previous post. Forward motion still looks to be slowing if ever so painfully.
for a while yesterday the center looked like one of those bouncing balls over a sentence you sing along with..
and it's that 1% that has all on here in a tizy.
Yup! Total flight hours in all types is just over 9000. Loved my time in the Worlds Most Powerful Nuclear Navy!! :))
Its weather, there really isn't any, but here is my take
Igor is pretty much on track as of right now and a recurve is most likely. However, even the NHC notes there is a large cone of error on days 3-5 as the models are disagreeing more then they were.
If Igor ends up on the southern end of the forecast cone; which is possible; the steering could be different than if he were to go down the center of it. That cone is very wide and if the trofs are as flat as the NHC says they are; Igor being just a few degrees further south could impart a totally different track than forecasted.
Let us not also forget that Bermuda is in the crosshairs of that cone; even if it were to turn NW and north, Bermuda is in danger of being hit by a strong hurricane.
We will just have to see how it all plays out, to try say definitely one way or the other what Igor will do is pretty pointless right now, because it just leads to bickering.
from the looks of it 92L got a chance to shoot the straights "opinon"
Link
I posted the link to that earlier
Got it - thanks - the link is good.
haha, I noticed that as well.
He will start turning very soon.. by midnight at the latest. The eye will be completely above 18 North..
Why?
Because the trough will have moved into the ridge enough and he will have gone west enough that the coriolis effect which pulls a cyclone north as well as spins it up will be able to overcome the weaker section of the ridge and pull him north.
It was doing that this afternoon.
Looks to be holding strong on this. Link
Doesn't mean it'll stay all week. But for now it's there.
Good afternoon everyone. Storm, you shut some mouths with that post ;-)
Igor
Katrina
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).
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS, MD
300 PM EDT MON SEPTEMBER 13 2010
6-10 DAY OUTLOOK FOR SEP 19 - 23 2010
"""OFF THE ATLANTIC SEABOARD, MOST
MODELS ANTICIPATE A TROUGH, AND A RELATIVE WEAKNESS IN THE SUBTROPICAL RIDGE.
THIS WEAKNESS INDICATES A POSSIBLE PATH FOR FUTURE TROPICAL CYCLONES. THIS
FEATURE IS MOST STRONGLY DEPICTED BY THE ECMWF AND CANADIAN RUNS. TWO WEEKS
AGO, IT WAS THE GFS-BASED SOLUTIONS THAT PREDICTED THE DEEPEST TROUGHS IN THIS
AREA."""
Nice,answers that, now whats a ridge finger?
Ummm never mind.
SW - There are four storms listed there, no mention of "pumping" anything, and yet this year it seems that Earl, Danielle, and now Igor were all "pumping" the same ridge? Shame on that ridge.
If it does happen, I don't think the term to use is "pumping"...
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