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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Storms never move in straight lines and it's still moving west . Do I need to issue a wobble watch warning for WU and other weather forums due to Igor ?
11 AM: 17.5 N
Guess it did take a south jog/wobble after all...
If I lived in Bermuda, I'd be nervous right now.
Whats causing him to jog slightly to the south? I know Hurricanes wobble all the time, in fact that they never really hold a straight line course, but to get a wobble to the south vs. north? Anyone with idea on this or is just your typical wobble?
Can someone help me out please. Is this not wind direction and the other wind speed ?
NOAA2 WXWXA 92L3 HDOB 31 20100913
141330 1613N 07829W 6437 03851 0079 +067 +032 024020 021 021 003 03
141400 1611N 07829W 6443 03841 0076 +068 +026 014017 018 010 002 03
141430 1610N 07827W 6441 03848 0078 +067 +033 014016 018 027 003 03
141500 1608N 07825W 6440 03843 0079 +063 +053 019017 018 037 005 03
141530 1607N 07824W 6439 03847 0077 +063 +060 005016 017 040 011 00
141600 1605N 07822W 6442 03841 0080 +063 +045 008018 019 038 004 00
141630 1604N 07820W 6441 03843 0083 +061 +048 012015 018 035 003 00
141700 1602N 07818W 6440 03845 0084 +061 +049 025016 017 035 008 00
141730 1601N 07817W 6439 03847 //// +061 //// 044010 014 036 013 25
141800 1600N 07815W 6410 03884 //// +056 //// 060014 018 /// /// 25
141830 1600N 07813W 6436 03849 //// +059 //// 080010 011 /// /// 25
141900 1601N 07811W 6437 03848 //// +060 //// 045009 011 027 006 21
141930 1603N 07809W 6423 03869 //// +055 //// 052009 013 030 008 21
142000 1604N 07808W 6427 03864 //// +059 //// 007019 021 032 008 21
142030 1605N 07806W 6425 03866 //// +061 //// 023016 019 033 006 21
142100 1606N 07804W 6430 03861 0076 +064 +062 010015 018 030 006 00
142130 1607N 07802W 6441 03846 0085 +059 +064 009009 011 032 006 00
142200 1608N 07800W 6436 03855 //// +054 //// 008005 006 032 007 21
142230 1609N 07759W 6433 03859 //// +060 //// 037013 015 028 006 21
142300 1610N 07757W 6424 03869 //// +055 //// 028016 017 027 005 21
All that is similar to Hurricane Luis
Depends on the strength of the trough vs. ridge. There have been several instances where a hurricane has "pushed back" a trough because a) the trough was too shallow or b) the subtropical ridge was to strong. This is where that old wives tale occurs about a strong hurricane can create its own environment and "steer" itself. Not the case, just means the ridge pattern was stronger than the troughing so the storm remains on course. Hard to explain without visuals.
I could see this storm push 50 ACE by the time it is done
Maybe so, but none of that means that the next trough isnt gonna come and make him turn out. The end result will be the same, just like it was with Earl. No U.S. Landfall!
The first trough to the north is keeping him on a westward movement.
In your blog today you mentioned:
This second trof exiting the U.S. coast, should be able to reinforce the weakness, however my concern is, if it flattens out anymore, with the already zonal flow on its southern edge, that Igor could be allowed to nudge even a little further west before his turn. He's already busted the first trof.
With the flattening out of the second trof, the pumping of the ridge from Igor, and given Igor's current postion, is it out of the realm of possibilities that maybe Igor is too far positioned away from the trof to be turned as sharp north?
I'm thinking some northward influence by the second trof but then I am thinking that Igor goes more 275/280 which would throw Igor further west of the current forecasted trac.
Second question is if the above is a possibility, how does that affect future tracs for Igor? Is there a 3rd trof that could pull Igor away before threatening the US coast?
Interesting comment on the lightning issue....I saw a TV show on History Channel recently and there is a lightening "lab" at FSU and one of the Professors is studying exactly that; the correlation between lighting near the core of a hurricane and rapid intensification issues.
Great post could not have said it better myself. The pattern for weeks now has not been condusive for cv strikes.In general the odds any cv storm making the trek in any given year are actually quite small. Everything has to set up just right.
Since the motion is official 265 degrees (5 degrees south of due west), this is a bit more than a wobble or even a jog. Wobbles and jogs even out over several hours.
Actually, StormW just explained it on his met blog. He doesn't seem to think it's an old wives tale.
Quoting:
Pumping the ridge is a term we use when a strong hurricane, generally CAT 4 or above, modifies the environment around it. The outflow from a storm so deep, if the storm is oriented in a more E-W fashion, will heat the atmosphere enough north and NW of the storm, that it actually reinforces that portion of the ridge...hence a more W to WNW motion in a hurricane like Igor.
Very close to the model that is Not Good At Predicting Stuff.
Oh, now that's reassuring...
(Sarcasm flag: ON)
Reed, I'd say that I respectfully disagree with you on 92Ls steering influence on Igor. I don't think that it's zonal flow is strong enough to push him even remotely off his westerly motion. I may be wrong, of course..
Click the magnifying glass to view full image and it almost looks like you are in the plane. ;^)
click here
I could understand the importance of Igor moving at 265 vs. 270 if it was the difference between a Miami,FL. landfall or points further north, but this isn't that situation.
Doubt it, though depends if this track is near correct. He's already trucking some speed by the end of the advisory. He might be at a pretty high latitude by the middle of next week. Seems he may well go through a EWRC by tomorrow. He'll drop a bit more than just 5kts, I would have thought.
I'll reckon... around the 35 to 36 ACE area. Just shy of Ike, but far surpassing Earl.
... they do tend to wobble
Its that timing that has me concern as it may just approach the US east coast before the recurve. I hope the NHC is right with Igor's future track.
Gauging the two's experience, profession, and expertise...I'll go with Chuck. No offense SW, your analysis is always highly anticipated.
Hey Hey, I third it!
There is a fair amount of uncertainty in that discussion.
I wouldn't simply dismiss outright some westward shenanigans later on.
[Sarcasm Flag: OFF] :)
HWRF agrees for the next 12 hours. (At least as of the 0 Z interpolated to 6 Z iteration)
Hey SJ!
The -NAO is more like a match that ignites the pattern, but not the direction where they go. The AZORES ridge located just to the NW of Africa has been much stronger than the Bermuda ridge so far this season...meaning storms that ride the periphery of the Azores are apt to be 'fish" or out to sea systems. Pull up a map of 500mb heights over the Atlantic and you will see the Azores ridge running the traffic pattern, and NOT the Bermuda ridge.2005 it was the opposite, so hemispheric steering currents were flowing toward the US...not so much in 2010. I think that is changing somewhat tho...the Azores ridge is extending farther out West in the Atlantic.Look at the paths of Colin, then Danielle, then Earl/Fiona...each storm closer to the US, but again not ideal for landfalling US. The window is closing fast across the eastern atl and in about 2 weeks its time to look close to home were i think things will continue to be rather active and we may see some threats to the southeast in given time.
Being a complete novice, I try to keep an open mind to learnng. And I don't know all the players here. I'm not familiar with Chuck at all. What does he do?
Bog Walk Gorge closed
Jamaica Observer
Monday, September 13, 2010
THE Bog Walk Gorge in St Catherine is now closed to vehicular traffic, as a result of flooding in the area.
This morning, water levels within the Gorge were recorded at 13 feet, well in excess of the eight feet critical level, the Office of Disaster Preparedness and Emergency Management (ODPEM) said.
Meanwhile, ODPEM is advising that as a result of the flash flood warning that is currently in effect for all parishes, extreme care must be taken when using flood prone areas.
Motorists and pedestrians are being advised to
• Remain calm.
• Monitor your radio.
• Avoid flooded waterways.
• Do not walk through heavy pools of water.
• Wrap important documents in a water resistant container.
We have some real psychos on this thread wishing these storms would hit the US. Keep bermuda in your prayers
lol
He's a TV met in South Carolina.
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