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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4246. barotropic
4:06 PM GMT on September 13, 2010
Quoting originalLT:
Post #4180, very nice proof!


Thanks, but I got slammed pretty hard about it...some I guess dont get the idea.
Member Since: August 22, 2010 Posts: 0 Comments: 652
4245. 1992Andrew
3:07 PM GMT on September 13, 2010
The CMC has Igor slide swiping the Northern Leeward Islands. They may receive a few outer bands. Earl, at Igor's current distance from the islands, was forecast to pass far north of the islands. It is true, however, that Igor's current position is far more north than was Earl, but still, the northern leeward islands may have to watch the system. The NHC is superb at forecasting in general, but it doesn't have a pristine record during times of recurvatures.
Member Since: July 20, 2010 Posts: 0 Comments: 205
4244. CaneHunter031472
2:33 PM GMT on September 13, 2010
Quoting help4u:
Already turning north according to twc can we move on from the west casting now.

And you use The Weather Channel as a source? lol.
Member Since: August 1, 2007 Posts: 0 Comments: 182
4243. jeffs713
2:28 PM GMT on September 13, 2010
NEW BLOG
Member Since: August 3, 2008 Posts: 16 Comments: 5885
4242. Floridaweathergirl
2:14 PM GMT on September 13, 2010
It's good to know that neither Igor, 92L, or T.S. Julis are headed for Florida. We were scared about Igor but seems he is going North according to the NHC.
Member Since: August 3, 2010 Posts: 0 Comments: 41
4241. Waltanater
2:05 PM GMT on September 13, 2010
Quoting PanhandleChuck:


+1
I "approve" that message! LOL
Member Since: May 16, 2010 Posts: 0 Comments: 1472
4240. farhaonhebrew
2:03 PM GMT on September 13, 2010
HURRICANE IGOR DISCUSSION NUMBER 20
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112010
1100 PM AST SUN SEP 12 2010
THE MEAN MOTION IS 270/11...BUT IGOR HAS BEEN WOBBLING A LITTLE TO
THE SOUTH OF THAT VECTOR.
Member Since: July 14, 2008 Posts: 0 Comments: 248
4239. Jax82
2:02 PM GMT on September 13, 2010
Monday!
Member Since: September 2, 2008 Posts: 1 Comments: 1261
4238. beeleeva
2:01 PM GMT on September 13, 2010
Quoting dracko19:
For those of you who think the GULF is safe from storms this year, take a look at the GFS map for Sep 28.



It shows a large and powerful Hurricane building right outside Texas. Now, keep in mind, this is 2 weeks off and they chances of it being right are about 50/50 at best. Still, I wouldn't relax if I lived on the Gulf. ALWAYS pay attention to what is happening with the weather if you live down there this time of year.
Lets hope 2 weeks out is pushing the envelope on model reliability.....
Member Since: July 22, 2008 Posts: 0 Comments: 85
4236. SevereWeather
1:59 PM GMT on September 13, 2010
NEW BLOG

NEW BLOG

NEW BLOG

NEW BLOG

NEW BLOG

NEW BLOG

NEW BLOG

NEW BLOG
Member Since: August 20, 2010 Posts: 0 Comments: 38
4235. barotropic
1:59 PM GMT on September 13, 2010
Quoting RecordSeason:
4200:

Actually, the only thing it "prooves" is that neither he nor you know anything about geometry or algebra, specifically mid-point theorem...


Location and movement are two different things. If the bottom edge of a tire 20 inches in diameter is rolling on a rail (the 17.5 line) heading west towards a point and the center point of the tire is 10 inches above the rail other than diameter what difference does it make if the tire shrinks to 10 inches and the center point is now 5 inches above the rail "but" continues rolling on the same rail (the 17.5line) heading west towards the same point.............are both tires not going to end up in the same spot?
Member Since: August 22, 2010 Posts: 0 Comments: 652
4233. Waltanater
1:57 PM GMT on September 13, 2010
Quoting help4u:
Already turning north according to twc can we move on from the west casting now.
I don't know how you can say that! According to visible satellite, it is still going due west!
Member Since: May 16, 2010 Posts: 0 Comments: 1472
4231. originalLT
1:54 PM GMT on September 13, 2010
4216, I got a 90 out of 100 on my geometry regents! Frankly, were are splitting hairs here. The general movement is West.
Member Since: January 31, 2009 Posts: 0 Comments: 7614
4230. DarIvy959810
1:53 PM GMT on September 13, 2010
Quoting Neapolitan:
FWIW, Igor's ACE is already higher than 18 of 2005's named storms, and by tomorrow alone it'll be higher than 22 of 2005's. (As I've mentioned previously, ACE for this year's Danielle is higher than all but three of 2005's storms, while Earl's is higher than all but two).

So, yes, long-track CV storms add a lot to ACE totals...though it should be noted that of the six most powerful 2005 storms--Dennis, Emily, Katrina, Ophelia, Rita and Emily--none were CV-type storms.

Emily could be considered but not as EARL and IGOR
2005 ACE was high due to the number of 28 storms but this year IGOR could have the highest ACE since Comrade IVAN 6 years ago, a record. Since IVAN the Terrible, none storms had an ACE higher than 40
Member Since: May 28, 2010 Posts: 0 Comments: 171
4229. SevereWeather
1:53 PM GMT on September 13, 2010
Quoting Kristina40:
I think I speak for the majority here, it would be nice if people left their political baggage at the door. We have a Cat 4 Hurricane and several other areas of interest to watch and discuss on this TROPICAL WEATHER blog, if you really must discuss politics go to a political blog.


+ 10

I have opinions. STRONG OPINIONS. But now's not the time. Lot's of weather to discuss. Save the political nonsense until January.

I approved this message.
Member Since: August 20, 2010 Posts: 0 Comments: 38
4228. stillwaiting
1:51 PM GMT on September 13, 2010
Igors growing in size!!!
Member Since: October 5, 2007 Posts: 20 Comments: 4970
4227. stillwaiting
1:51 PM GMT on September 13, 2010
Igors growing in size!!!
Member Since: October 5, 2007 Posts: 20 Comments: 4970
4226. hercj
1:51 PM GMT on September 13, 2010
Quoting Skyepony:
Today's the big day..Igor is suppose to take the weakness & end up near or over Bermuda.. We'll see, still a little left of models & offical. Overall the models have shown improvement over the last 24hrs with Igor. CMC still has a commanding lead with 48nm error in the last 24hrs AVNO follows with 53, the rest follow with 70nm error or more for the last 24hrs..


Little more south & I think we could improve the odds for Igor to be a cat 5.. Lets hope he's not attracted by warm water:)


92L~ I could see being a TD or TS by Yucatan, strengthen in the BOC & hit this years popular spot in North Mexico.

Good morning Sky. Did 43 recover last night on Barbados? It looked like they were headed that way but couldn't find anything to confirm it.
Member Since: September 5, 2009 Posts: 0 Comments: 319
4225. stillwaiting
1:51 PM GMT on September 13, 2010
Quoting dracko19:
For those of you who think the GULF is safe from storms this year, take a look at the GFS map for Sep 28.



It shows a large and powerful Hurricane building right outside Texas. Now, keep in mind, this is 2 weeks off and they chances of it being right are about 50/50 at best. Still, I wouldn't relax if I lived on the Gulf. ALWAYS pay attention to what is happening with the weather if you live down there this time of year.
...,14+ days,gimmie a break,should be taken with a grain of salt,not even close to reliable,what's keepn them from classifying 92l?????
Member Since: October 5, 2007 Posts: 20 Comments: 4970
4223. angiest
1:50 PM GMT on September 13, 2010
Quoting dracko19:
For those of you who think the GULF is safe from storms this year, take a look at the GFS map for Sep 28.



It shows a large and powerful Hurricane building right outside Texas. Now, keep in mind, this is 2 weeks off and they chances of it being right are about 50/50 at best. Still, I wouldn't relax if I lived on the Gulf. ALWAYS pay attention to what is happening with the weather if you live down there this time of year.


GFS has been developing a Caribbean/Gulf system consistently. Track is not important yet, the presence of the storm is.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
4222. Orcasystems
1:49 PM GMT on September 13, 2010
Still looking for the Centre.


Member Since: October 1, 2007 Posts: 81 Comments: 26511
4220. Patrap
1:49 PM GMT on September 13, 2010
12z Early Cycle NHC model tracks
Invest92
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)




Dynamic Models (More sophisticated models)



Member Since: July 3, 2005 Posts: 426 Comments: 128668
4219. BobinTampa
1:49 PM GMT on September 13, 2010
ewnay logbay. el bloggo del newo.

Member Since: August 14, 2008 Posts: 0 Comments: 536
4215. BobinTampa
1:48 PM GMT on September 13, 2010
new blog.
Member Since: August 14, 2008 Posts: 0 Comments: 536
4214. Patrap
1:47 PM GMT on September 13, 2010
92L Rainbow

Member Since: July 3, 2005 Posts: 426 Comments: 128668
4213. CoopsWife
1:47 PM GMT on September 13, 2010
Quoting Kristina40:
I think I speak for the majority here, it would be nice if people left their political baggage at the door. We have a Cat 4 Hurricane and several other areas of interest to watch and discuss on this TROPICAL WEATHER blog, if you really must discuss politics go to a political blog.

+1
Member Since: June 19, 2006 Posts: 63 Comments: 4175
4212. PanhandleChuck
1:47 PM GMT on September 13, 2010
Quoting Kristina40:
I think I speak for the majority here, it would be nice if people left their political baggage at the door. We have a Cat 4 Hurricane and several other areas of interest to watch and discuss on this TROPICAL WEATHER blog, if you really must discuss politics go to a political blog.


+1
Member Since: May 13, 2008 Posts: 0 Comments: 1414
4211. Kristina40
1:47 PM GMT on September 13, 2010
I think I speak for the majority here, it would be nice if people left their political baggage at the door. We have a Cat 4 Hurricane and several other areas of interest to watch and discuss on this TROPICAL WEATHER blog, if you really must discuss politics go to a political blog.
Member Since: June 27, 2010 Posts: 0 Comments: 760
4210. farhaonhebrew
1:46 PM GMT on September 13, 2010
Quoting barotropic:


Igor at 17.7 Notice the location of south eyewall and north eyewall



5 hrs later South eyewall remains exact same location North begins to drop



3 hrs later South eyewall still same latitude, while north wall comes south (contracting inward)



Two hours later, Igor at 17.6N - N eyewall dropped (contracted in) near 2 tenths of degree. S eyewall...exact same as 10+ hours earlier.


Last night amid pages and pages of comments that Igor was possibly begining to move south of west, I made a simple comment. "Igor was not moving south at all, as he was loosing his annular "look", his N eyewall was pulling in south, giving the illusion that he was jogging south". What a mistake. Some nasty comments came about and a comment or 2 about my "nautical ability" to note headings was made. My comment was simple and easy to understand - but the reaction was NASTY. So here is the "proof" I see required on here so much. Igor never moved south last night at all. As a matter of fact, the south eyewall moved along 17.5 for near 10 hours as if it were on "rails". THE PICTURES DONT LIE. The only thing that moved south was the north eyewall (contracting inward), not the storm. The storm heading remained exactly the same with a location drop (center point between the two walls) from 17.7 N to 17.6N over the near 10 hour period. The location dropped a tenth because the N wall dropped 2tenths (as seen above). Hence center point between N and south eyewall net a drop of a tenth of a degree. There was such a desire for some to see a south movement that my point was slammed bigtime. I didnt make a big deal about my comment, others did. So there (above) is the proof.......


HURRICANE IGOR DISCUSSION NUMBER 20
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112010
1100 PM AST SUN SEP 12 2010
THE MEAN MOTION IS 270/11...BUT IGOR HAS BEEN WOBBLING A LITTLE TO
THE SOUTH OF THAT VECTOR.

Member Since: July 14, 2008 Posts: 0 Comments: 248
4208. BobinTampa
1:46 PM GMT on September 13, 2010
random tidbit: insurance losses from Tropical Storm Hermine expected to approach $100 million in Texas.

Member Since: August 14, 2008 Posts: 0 Comments: 536
4207. barotropic
1:46 PM GMT on September 13, 2010
Quoting RecordSeason:
4180:

Man you are hard headed.

The STORM has it's position defined by the center point of the eye.

You admit the northern eye-wall moved south and continues to do so, while you also claim the southern eyewall did not move north.

therefore, the mid-point between the eye-walls MUST have moved south.

By definition, the STORM moved south equal to the center of the eye, which in this case is 0.15 degrees and increasing.
Quoting RecordSeason:
4180:

Man you are hard headed.

The STORM has it's position defined by the center point of the eye.

You admit the northern eye-wall moved south and continues to do so, while you also claim the southern eyewall did not move north.

therefore, the mid-point between the eye-walls MUST have moved south.

By definition, the STORM moved south equal to the center of the eye, which in this case is 0.15 degrees and increasing.
Member Since: August 22, 2010 Posts: 0 Comments: 652
4206. barotropic
1:46 PM GMT on September 13, 2010
Quoting RecordSeason:
4180:

Man you are hard headed.

The STORM has it's position defined by the center point of the eye.

You admit the northern eye-wall moved south and continues to do so, while you also claim the southern eyewall did not move north.

therefore, the mid-point between the eye-walls MUST have moved south.

By definition, the STORM moved south equal to the center of the eye, which in this case is 0.15 degrees and increasing.
Quoting RecordSeason:
4180:

Man you are hard headed.

The STORM has it's position defined by the center point of the eye.

You admit the northern eye-wall moved south and continues to do so, while you also claim the southern eyewall did not move north.

therefore, the mid-point between the eye-walls MUST have moved south.

By definition, the STORM moved south equal to the center of the eye, which in this case is 0.15 degrees and increasing.
Member Since: August 22, 2010 Posts: 0 Comments: 652
4205. BLee2333
1:45 PM GMT on September 13, 2010
Quoting dracko19:
For those of you who think the GULF is safe from storms this year, take a look at the GFS map for Sep 28.



It shows a large and powerful Hurricane building right outside Texas. Now, keep in mind, this is 2 weeks off and they chances of it being right are about 50/50 at best. Still, I wouldn't relax if I lived on the Gulf. ALWAYS pay attention to what is happening with the weather if you live down there this time of year.


50/50 is too generous. 2 weeks out I'd plan a BBQ at that location!
Member Since: January 6, 2009 Posts: 0 Comments: 217
4204. Patrap
1:45 PM GMT on September 13, 2010
IGOR Floater - Rainbow Color Infrared Loop

TFP's are available
Member Since: July 3, 2005 Posts: 426 Comments: 128668
4203. Neapolitan
1:45 PM GMT on September 13, 2010
Quoting KanKunKid:


Look at the Dvorak. I would say it needs more organization. Maybe by tomorrow TD.


I did. It may be tomorrow, but I don't think so; organization looks better, and Dvorak should fall in line later today. I'm just sayin'...
Member Since: November 8, 2009 Posts: 4 Comments: 13556
4200. originalLT
1:45 PM GMT on September 13, 2010
Post #4180, very nice proof!
Member Since: January 31, 2009 Posts: 0 Comments: 7614
4199. Patrap
1:44 PM GMT on September 13, 2010
IGOR

Rainbow

Member Since: July 3, 2005 Posts: 426 Comments: 128668
4198. Cotillion
1:44 PM GMT on September 13, 2010
Quoting Tango01:


Comparisons between 1950 and 2005 may not be completely fair because in 1950 many of the sensing technologies used nowadays had not been invented, yet. So some storms may not had been detected in 1950.


For this purpose, it is fair. There were no storms below 0.49 ACE between 1875 and 1969, correct (yet, this seemingly happens on a semi-regular basis in the past 10 years. Off the top of my head, the last year to have all storms above 1 in ACE was 1997). However, even if these 1-3 storms were missed, the ACE won't be massively different nor will the comparison. It'd just be 12 or so storms to an ACE difference of 2 or 3.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
4197. SeaMule
1:44 PM GMT on September 13, 2010
as has been the case all season, the hurricane will be more west of the forecast. It will be interesting to see how Igor pans out. way to early to call it a fish spinner.

Andrew was suppose to spin out and away from the CONUS...but things changed.

plenty of time for the weather to change.

this is one of "those" storms.

name is Igor too. ya just get the feeling....ya know?
Member Since: October 29, 2007 Posts: 0 Comments: 113
4196. Patrap
1:44 PM GMT on September 13, 2010
12z Early Cycle NHC model tracks
Igor
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)





Dynamic Models (More sophisticated models)




Member Since: July 3, 2005 Posts: 426 Comments: 128668

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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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