92L still a threat to develop; Igor a hurricane; TD 12 forming near Africa

By: Dr. Jeff Masters , 2:18 PM GMT on September 12, 2010

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Tropical disturbance (92L) over the Central Caribbean, a few hundred miles south of the Dominican Republic, remains a threat to develop into a tropical depression. Satellite loops this morning show 92L may be starting to form a surface circulation, and an Air Force Hurricane Hunter aircraft will investigate 92L this afternoon to see if a tropical depression is forming.

The storm has only a modest area of heavy thunderstorm with limited low-level spiral banding and upper-level outflow, thanks to an infusion of dry air last night that disrupted the storm. Long range radar out of Puerto Rico shows that heavy rains are affecting that island, but there is no rotation to the radar echoes evident. Wind shear over 92L is low, 5 - 10 knots. The waters beneath are hot, 29.5°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 could interfere with development at times over the next few days.


Figure 1. Morning satellite image of 92L.

Track forecast for 92L
The disturbance is moving west to west-northwest at 15 mph, and steering currents favor a continuation of this motion for the next three days. Model support for development is scattered. The GFS and NOGAPS models do not develop 92L. The GFDL and ECMWF models predict development, with a track taking 92L into Belize or Mexico's Yucatan Peninsula on Wednesday. On this track, the southern Dominican Republic can expect heavy rains of 3 - 6 inches today through Monday morning; southern Haiti can expect similar rains tonight through Monday night, and Jamaica and the Cayman Islands can expect heavier rains of 4 - 8 inches Monday and Tuesday. Eastern Cuba can expect rains in the 2 - 4 inch range. 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 south of the Texas border.

Intensity forecast for 92L
NHC is putting the odds of 92L developing into a tropical depression by Tuesday at 50%; I'd put them higher, at 70%. However, time is running out for 92L to become a hurricane before hitting the Yucatan Peninsula on Wednesday. Given the current disorganized state of 92L, it would be difficult for it to intensify quickly enough to become a hurricane by then. The storm may also suffer another of its mysterious evening collapses, where it loses most of its heavy thunderstorm activity. However, the SHIPS model predicts wind shear will remain low, 5 - 10 knots, through the period, and water temperatures are certainly warm enough to support development. The main detriment to intensification is likely to be dry air, and 92L could wrap in some of the dry air to its northwest at times, slowing down development. There are a number of research flights being made into 92L this afternoon that should help long-term efforts to make better predictions in the future on whether or not disturbances like this will develop or not.


Figure 2. Morning satellite image of Igor.

Igor
Hurricane Igor appears destined to become a large and powerful major hurricane over the Central Atlantic in the days to come. Wind shear is low, 5 - 10 knots, and is expected to drop below 5 knots for the next five days. Waters are warm, 28°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. Igor is undergoing a period of rapid intensification today, and will probably be a Category 3 or 4 hurricane by Monday.

The track forecast for Igor remains unchanged. Igor will move west under the influence of a strong ridge of high pressure for the next 2 - 3 days, 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 may be a threat to Bermuda, and 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 - 12 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 affecting any land areas. Recent runs of the ECMWF model indicate that these troughs may not be as intense as previously thought, so it is possible Igor has a higher chance than usual to hit land than climatology suggests. One wild card may be the possible development of TD 12 behind Igor. If TD 12 develops into a hurricane, and moves close to Igor, as some of the models are suggesting, the two hurricanes could rotate around a common center, forcing Igor more towards the coast of the U.S. The long term fate of Igor is difficult to predict at this point.

Tropical Depression Twelve forms
Tropical Depression Twelve formed between the Cape Verdes Islands and coast of Africa this morning, and is already affecting the Cape Verdes with winds near tropical storm strength; sustained winds of 35 mph were recorded in the northwest Cape Verdes this morning. You can follow the progress of TD 12 through the Cape Verdes today using our wundermap.

Next post
I'll have a new post Monday morning, and perhaps late this afternoon if events warrant.

Jeff Masters

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Quoting weatherwatcher12:

The hh's are on their way in so we should know soon.


Yeah, I read that earlier that they were headed out this afternoon. Apperently more eveningtime. Good to hear. Definitely will watch the data coming in!
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"Miss Piggy" approaching 92L.

223230 2021N 07327W 5263 05484 0290 -024 -048 076013 014 /// /// 03
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Afternoon Drak. Where, in your opinion is the center of 92L? NHC has it south over water. Looks to me as if it's forming over landmass.
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Quoting kmanislander:


The last few satellite frames show the system going from being oriented from the SW to the NW in an elogated disorganized fashion to being more "upright" in the middle with a developing ball of convection. There is also evidence of good rotation near 16 / 73.

It still has work to do but there are signs of a change in the structure towards some development occurring.
Thank you.
Member Since: October 9, 2008 Posts: 0 Comments: 8436
Sure its a BAD IDEA. But they are already playing with those toys. The Alaska project is not the only one.... Some European Union countries are building HAARP projects more powerful than the US...
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Based on everything I've saw, we should have a 150-160 mph storm at 11PM.

We'll likely have Julia at 8PM
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Quoting Herbertsbox:


What's the JH rule, if you don't mind
Kman tought me last night. Basically, if a wave cannot close off a low before 63 degrees in the carribian, it will not form untill 75 west. Think thats right lol
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1988. IKE
Is this GFS reloading again for the 2 favorite tracks in 2010?

12 days...



360 hour frame says yes.
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Quoting txjac:
He is here ...and I agree, great job kman


Hi there, thanks. We still have to see if it can continue to improve but this is the area where things start coming together for systems that have struggled in the Eastern and Central Caribbean.
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Sure its a BAD IDEA. But they are already playing with those toys. The Alaska project is not the only one.... Some European Union countries are building HAARP projects more powerful than the US...
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Quoting hydrus:
Dvorak shows Igor,s mighty, mighty power. There is also a massive amount of moisture with this system. water is very wet....

Compared to the storm's overall size, Igor's eye is pretty big.
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1984. MZT
I made a quick YouTube search and can't find it now - but there is a vid out there of someone in the eye of one of the Gulf storms during daylight. They filmed the horizon in all directions and you did get the sense of being "in a hole". They are tall clouds!
Member Since: September 24, 2005 Posts: 0 Comments: 793
Classic La-Nina year...Slow start, active, active finish. We are no where near done however. We should have Karl or whatever the storm's name is by the end of the week. Laruen should be here by the beginning of next week.

TD 12 -> Julia

92L -> Karl, "K" storm

Wave behind TD12 -> Lauren

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1981. hydrus
Quoting weatherwart:


Water is very wet? Uhm. lmfao! I'm sorry, that's just cracks me up.
It was an attempt at humor...I am in a good mood today, but I hate cat food now. I read the ingredients on the can and there is no cat in it....They lied...
Member Since: September 27, 2007 Posts: 1 Comments: 22718
Quoting osuwxguynew:
Good Evening All!

92L starting to look more interesting...

Currently, the deepest convection could be inducing a surface circulation to form. Hard to tell underneath the clouds and no weather obs close enough to be sure.

Strong southerlies to the east of the deepest convection evident in the cumulus cloud streets. Looks like some northeasterlies just south of Haiti's south coast. No sign of any westerlies yet obviously.

The hh's are on their way in so we should know soon.
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1979. Max1023
Quoting leo305:


that's what I thought with earl, but dry air and southerly shear stopped it from reaching CAT 5 strength, we'll see


Earl had twice as much shear and a LOT more dry air, if you look on WV the dry air is being pushed back more than 3 degrees west of the CDO edge. Also, the airmass is not as dry as Earl fought off. Hurricanes this strong do not usually entrain dry air all the way to the core, there is too large of a moisture field surrounding them.
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Quoting stormwatcherCI:
In your opinion how is it looking this evening ?


The last few satellite frames show the system going from being oriented from the SW to the NE in an elogated disorganized fashion to being more "upright" in the middle with a developing ball of convection. There is also evidence of good rotation near 16 / 73.

It still has work to do but there are signs of a change in the structure towards some development occurring.
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Quoting txjac:
Can I ask a stupid question?

How deep is that hole? If one were standing in the center of the eye and looked up how high would be be? It looks deep, real deep.

Thanks in advance


*wink wink*
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Quoting sunlinepr:
Well, it seems that the only solution would be to build a weather manipulation, HAARP antenna in the Caribbean... Like the one in Alaska; http://www.haarp.alaska.edu/ Official definition : to induce a small, localized change in ionospheric temperature so physical reactions can be studied by other instruments located either at or close to the HAARP site’. Unofficial definition: HAARP operates as, a gigantic heater that can cause major disruptions in the ionosphere, creating not just holes, but long incisions in the protective layer that keeps deadly radiation from bombarding the planet’. So it can create a MAN INDUCED HIGH PRESURE AREA 400 X 400 miles that can "Theorically", Deviate Hurricanes.....

Bad idea to tamper with nature, bad things will happen.
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Quoting doorman79:


Kman nailed it! John Hope rule. I would give him kudos if he was here!


What's the JH rule, if you don't mind
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The Final T# of Igor has increased to 6.6 (which indicates a pressure of 934mb and winds of 130kt -- 150mph). The Raw T# is a little higher...up to 6.8.

2010SEP12 221500 6.6 934.2/ 2.0 /129.6 6.6 6.8 6.8 3.2T/18hr OFF OFF 16.74 -70.44 EYE 25 IR 17.66 46.79 COMBO
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Well, it seems that the only solution would be to build a weather manipulation, HAARP antenna in the Caribbean... Like the one in Alaska; http://www.haarp.alaska.edu/ Official definition : to induce a small, localized change in ionospheric temperature so physical reactions can be studied by other instruments located either at or close to the HAARP site’. Unofficial definition: HAARP operates as, a gigantic heater that can cause major disruptions in the ionosphere, creating not just holes, but long incisions in the protective layer that keeps deadly radiation from bombarding the planet’. So it can create a MAN INDUCED HIGH PRESURE AREA 400 X 400 miles that can "Theorically", Deviate Hurricanes.....
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1971. Max1023
Quoting txjac:
Can I ask a stupid question?

How deep is that hole? If one were standing in the center of the eye and looked up how high would be be? It looks deep, real deep.

Thanks in advance


About 15 Kilometers or 10 miles (ish). The colder the cloud tops the higher they go, some -85 degree tops go to 12 miles high.
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1970. leo305
Quoting Max1023:


The water shouldn't support a Cat 5 anyway, 28 degrees is usually not enough to even get you a high 4. The fact that Igor is almost certainly stronger than 125 knots suggests that what little shear that exists is having almost no effect on the cyclone. I didn't think it would get to 5 6 hours ago but it looks like one now.


that's what I thought with earl, but dry air and southerly shear stopped it from reaching CAT 5 strength, we'll see
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1969. will40
would love to see a shot of IGOR from the space station
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Good Evening All!

92L starting to look more interesting...

Currently, the deepest convection could be inducing a surface circulation to form. Hard to tell underneath the clouds and no weather obs close enough to be sure.

Strong southerlies to the east of the deepest convection evident in the cumulus cloud streets. Looks like some northeasterlies just south of Haiti's south coast. No sign of any westerlies yet obviously.
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Quoting Kristina40:
Igor has a heart shaped eye...
He has a heart, were safe lol he really pretty unfortunately it's hard to admire a storm when you have even the slightest chance of being hit.
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1966. txjac
He is here ...and I agree, great job kman
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1965. Max1023
Quoting leo305:


yes but they would be blown apart from the south to the north, not from north to south, there is some light shear coming from the north choking it off a bit, which is why I think it might not hit CAT 5 strength just yet


The water shouldn't support a Cat 5 anyway, 28 degrees is usually not enough to even get you a high 4. The fact that Igor is almost certainly stronger than 125 knots suggests that what little shear that exists is having almost no effect on the cyclone. I didn't think it would get to 5 6 hours ago but it looks like one now.
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Quoting kmanislander:


Good afternoon

92L is closing in on 75W which, as you may recall, is the longitude I have been saying would be the threshold for it to develop if it did so at all. It appears to be near 16 N and 73 W at this time.


You popped up at the perfect timing lol!

see post 1960
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1962. Drakoen
92L seems to be firing some strong convection. Question is will it hold long enough to induce the formation of a surface circulation.

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Quoting kmanislander:


Good afternoon

92L is closing in on 75W which, as you may recall, is the longitude I have been saying would be the threshold for it to develop if it did so at all. It appears to be near 16 N and 73 W at this time.
In your opinion how is it looking this evening ?
Member Since: October 9, 2008 Posts: 0 Comments: 8436


Kman nailed it! John Hope rule. I would give him kudos if he was here!
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1959. txjac
Can I ask a stupid question?

How deep is that hole? If one were standing in the center of the eye and looked up how high would be be? It looks deep, real deep.

Thanks in advance
Member Since: Posts: Comments:
1958. leo305
Quoting Max1023:


I can't see anything as extreme as you are describing, it does look like the small amount of shear that exists is coming from 350deg however it looks to be less than 10 knots. Also, that could be caused by the ridge to the north of Igor resisting outflow a bit better than the flat upper levels to the south. A ridge produces anticyclonic flow which fights off outflow, this is restricting it slightly to the north. Once Igor approaches the trough to its NW (a couple thousand miles to its NW) the outflow in that direction will improve. Also, bands that far out would be blown apart by the outflow from the Eyewall anyway.


yes but they would be blown apart from the south to the north, not from north to south, there is some light shear coming from the north choking it off a bit, which is why I think it might not hit CAT 5 strength just yet
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Quoting stormpetrol:
92L firing deeper convection when usually this time of day its waning, another sign it might be finally starting to take off, jmo.


Good afternoon

92L is closing in on 75W which, as you may recall, is the longitude I have been saying would be the threshold for it to develop if it did so at all. It appears to be near 16 N and 73 W at this time.
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Quoting all4hurricanes:

I see a pink frosted donut, cat 5 coming up

Now I'm hungry! LOL
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Igor has a heart shaped eye...
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Quoting hydrus:
Dvorak shows Igor,s mighty, mighty power. There is also a massive amount of moisture with this system. water is very wet....


Water is very wet? Uhm. lmfao! I'm sorry, that's just cracks me up.
Member Since: August 18, 2008 Posts: 0 Comments: 884
1952. Max1023
Quoting leo305:


look at the outer bands to the north of the system, notice how they are getting blown apart by northerly shear.. and how IGOR's ouflow isn't as strong on the north side as the southern side


I can't see anything as extreme as you are describing, it does look like the small amount of shear that exists is coming from 350deg however it looks to be less than 10 knots. Also, that could be caused by the ridge to the north of Igor resisting outflow a bit better than the flat upper levels to the south. A ridge produces anticyclonic flow which fights off outflow, this is restricting it slightly to the north. Once Igor approaches the trough to its NW (a couple thousand miles to its NW) the outflow in that direction will improve. Also, bands that far out would be blown apart by the outflow from the Eyewall anyway.
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1951. hydrus
Dvorak shows Igor,s mighty, mighty power. There is also a massive amount of moisture with this system. water is very wet....
Member Since: September 27, 2007 Posts: 1 Comments: 22718
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A thing of beauty.


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1947. mbjjm
92L more clouds than rain

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Quoting PRweathercenter:

Sometimes if a storm is stronger, it can make it's track, it will be interesting if Igor is obedient or not, Bermuda and even the East Coast should keep an eye on this.



Yeah, rapidly intensifying hurricanes, or just extremely intense ones in general are known for defying forecasts unexpectedly, Charley was a great example.


Keep in mind, its not like it always happens, but it does happen enough times that we must keep a very close eye on Igor. That and the fact that is could end many lives if it makes landfall.


By the way, Igor's model consensus is not nearly as tight as Earl's was, and even Earl continued to push much farther west than the models had been saying all along, thank God it finally did turn north, but originally models consistently had it passing well east of Bermuda, it ended up less than 100 miles from NC, lol.
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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