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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But the skill for the year 2003 was far better for long range forecasts than the average of the last 5 years.
Why?
Was it the tracks of the systems?
Nothing here screams "easier to forecast than most years".
Not sure about the reasons myself. But, I can accept that our longer-range track forecasts have not improved significantly over the last 7 years.
He won't see me quote it either since I am also on his quite sizeable ignore list, but you are quite right.
I'll agree 100% is a bit high...99-98% would be a more accurate statement imho.
Ya know, you could be right. This is probably why 92L just can't get going. Good observation Ike.
Right now, based on whatever methods/models/sats/indexes, intuition,goat bones, 8-Ball, wive's tales, etc, etc, will Igor stray outside the current 5 day cone at any point between now and 8AM EDT Saturday?
Y/N?
I'd say no.
Link
I still think it's possible. Whatever is down there now is ill-defined. The system will be moving into warmer waters with greater depth which should help it maintain convection.
very well said!!!
Drak, you do have tremendous obs skills and forecasting skills, amazing job you do. Keep it up, not a lot of people have the potential you and Levi do.
I'd say chaotic.
Thank You............ :)
Thank You
Hey nothing against Storm, he's just as knowledgeable. I respect his opinions, just something I don't agree with him on. It's the scientific side of me. To me, its just a phrase thrown around on this blog to explain why a system isn't turning.
Thank You
Let me know if you need another one - I can send it to Chetumal for you! Let's hope 92L does not get its act together!
How saying the same as the NHC, is another point of view?
Igor is definitely a tough storm to develop, but within this area of Latitude and Longitude models have a tough time determining when the northward turn is to occur, once as the storm nears the Bahamas or north of the Greater Antilles islands, they become more accurate with a higher then average forecast confidence.
Non-linear dynamics is the more technical name for "chaos." In extremely simply terms, 1+1=2 is linear. That is, it is absolutely predictable. You always know with 100% certainty what the outcome is. However, what if 1+1=[1.9..2.03]? And what if that answer is somewhere different in that range each time? How are you going to wind up with the "correct" answer with any certainty? I am making gross simplifications here, but consider something as complex as the ocean-atmosphere system in which tropical cyclones exist. How do you account for all the variables? It all factors into track and intensity forecasts, and as we see there are plenty of things our models do not pick up on when it comes to forecasting intensity. And while track forecasts are definitely better, the assumptions built into the models may not always be correct, and we also don't know what small-scale features can have an impact (a butterfly opening its winds in Tokyo causing rain in NYC a week later).
Are any global models initializing Igor with the correct intensity? If not, how is that affecting their track forecasts? How many of the "hurricane" models like GFDL and HWRF are using this data as their initialization?
I have to agree with your analysis. That ridge is right in his face, where the trough that is hoped for as a savior seems a bit too weak and far north to inspire much confidence.
It seems that those who are in harms way in case of a missed or too late turn ought to be nervously rechecking their preparations, just in case. We shall see.
I agree with both points
That's you scientific analysis of Igor?lol
I think Bob is great at forecasting storms, I just think he's putting too much confidence in a forecast the NHC has very low confidence in. I read Levis, StormWs, and Bobs blog. I also like to view jasoniscoolman videos for comedy :P, with his updates along with Lady Gaga music.
the only thing that will stop it now is Puerto Rico....sad to say......
that is a tad too late for us islanders
Beell, was that supposed to be "wives tales" or "wise tails?" I'm confused! ;(
But, ummmm, you're likely right. Thanks.
those videos can be a little "fishy" sometimes...
Here is the box I am talking about. Hurricanes in this box at some point, models have had a hard time forecasting 5 day forecast tracks for these systems. The easy storms that come right to mind are Ike 2008, Earl and Igor of 2010. Bill might be a case as well of 2009, however he was pretty much forecasted very well by the GFS.
yes
Go-Jamaica.com says...
Several roadways across Jamaica are now blocked following overnight heavy rains.
The National Works Agency (NWA) says the Bog Walk Gorge in St. Catherine is now closed. As such motorists are being asked to use the alternative Barry or Sligoville roads.
The agency is also advising motorists to drive carefully along the Junction Main Road as there are land slippages along the roadway.
The John Hill Bridge to Free Town roadway in Clarendon is also flooded.
Several schools are also closed.
Irresponsible post at this point.
Be careful how you use the words "defy all models" , I used those same words with Earl and got jumped on by some here like tics on a bull :)BTW I agree with you 100%
So, yeah, GFS does the best it can with it's resolution, generates a first starting point for GFDL, steering winds (which it and other global models are best for), etc. But when GFDL is run, bogussing is used to insert the storm's parameters (RMW, windfield data, radii of winds, pressure deficit, beta shape parameter (steepness of the pressure gradient), etc.)
The bogussing functions started in the mid 90s.
Whoa! Isnt that akin to Idol worship?
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