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

Share this Blog
1
+

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

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 4196 - 4146

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 | 70 | 71 | 72 | 73 | 74 | 75 | 76 | 77 | 78 | 79 | 80 | 81 | 82 | 83 | 84 | 85Blog Index

4196. Patrap
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: 423 Comments: 127846
Quoting help4u:
Already turning north according to twc can we move on from the west casting now.


ummmm right.....
Member Since: Posts: Comments:
4193. hercj
Quoting weatherwart:


Excellent analysis. Thanks!

Very good. I enjoyed reading that. I hate models but like math it helps when you understand why the lines are going where they are going. Thank You
Member Since: Posts: Comments:
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.
Member Since: Posts: Comments:
Quoting CoopsWife:
Not to mention women on the blog. :)

REALLY enjoying the idea we are so powerful that we affect your behavior enough to blame us for it, LOL.


They dont like to admit it but we are always really in control
Member Since: Posts: Comments:
Quoting Halon056:
Just reviewing my earlier post on the ship report... What is a ship doing in the middle of tropical storm force winds??????


Working. And trying to stay out of the worst of it without totally disrupting their schedule and wasting available fuel supply.
Member Since: Posts: Comments:
i know that systems are pulled by areas of lower pressure. in this case Igor has lower pressure than any of the troughs. then how then could weaker systems pull stronger systems. i thought it was the opposite
Member Since: Posts: Comments:
4186. help4u
Already turning north according to twc can we move on from the west casting now.
Member Since: Posts: Comments:
4184. Skyepony (Mod)
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.
Member Since: Posts: Comments:
Quoting KanKunKid:


Like you didn't know.


ROFL - at 51 my years of power are LONG behind me! Compromise works much better at this stage of the game! :)

Of course, my MOM powers are ever increasing.....
Member Since: Posts: Comments:
Just reviewing my earlier post on the ship report... What is a ship doing in the middle of tropical storm force winds??????
Member Since: Posts: Comments:


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.......
Member Since: Posts: Comments:
4178. Tango01
I'm sorry for the double-post. Bad Internet connection today.
Member Since: Posts: Comments:
4177. luigi18
the TWC just said thet Igor is Turning north,People in the Leeward island are save!

really i dont trust them remenber Earl?
Member Since: Posts: Comments:
IGOR don't start his west/northwestard moving at 12z
It continues westward.
Member Since: Posts: Comments:
Quoting calder:
Beautiful storm, here's hoping that he doesn't hit anything. By the way, seems to be some confusion - Igor isn't and never was annular.


Definition of Annular – 1. the shape your head takes looking at two wobbles during a hurricane, thereby saying for a fact that it has changed course. 2. the angle your head is at when you are trying to classify the shape of a hurricane.

Cheers!
Member Since: Posts: Comments:
4173. Tango01
Quoting Cotillion:


Igor has no advisories posted.

---

Yeah, unreasonable would be a better word, KanKunKid. Also agree with the November observation.

---



It happens a fair amount.

2007 is a good example of that. 15 storms, but below average in ACE.

2005 eclipsed 1950 by 5 in ACE... despite having 14 more storms (15, but one was ST, therefore not counting) and 5 more hurricanes.

A big Cape Verde season tends to mean a big ACE season.


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.
Member Since: Posts: Comments:
Quoting jeffs713:

Stadium effect - check.
Beautiful storm - check.
large eye in comparison to the storm - check?

weaking flag off-check.
annular hurricane-not sure
fish-no way jose, besides Cape Verde already took the brunt for us and Bermuda yet to come.
re-curvature-I'm pretty confident in that "hint" "hint" at some point.
Member Since: Posts: Comments:
4171. Tango01
Quoting Cotillion:


Igor has no advisories posted.

---

Yeah, unreasonable would be a better word, KanKunKid. Also agree with the November observation.

---



It happens a fair amount.

2007 is a good example of that. 15 storms, but below average in ACE.

2005 eclipsed 1950 by 5 in ACE... despite having 14 more storms (15, but one was ST, therefore not counting) and 5 more hurricanes.

A big Cape Verde season tends to mean a big ACE season.


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.
Member Since: Posts: Comments:
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.
Member Since: Posts: Comments:
bermuda rarely takes a direct hit from major hurricanes
Member Since: Posts: Comments:
FWIW, 92L now has its lowest pressure (1006 mb), and winds are back to where they were before dropping a bit yesterday (25 knots). Is possible-Karl making a move?

Looking at the satellite I'd say yes. If things continue this way, I'm guessing we'll see a renumber to TD13 this afternoon/evening.
Member Since: Posts: Comments:
Quoting dracko19:
The big question on everyone's mind is where is IGOR going to end up? Let's look at the models this morning and see what's happening.

The NOGAPS model, which predicted some strong ridging over the NE USA coast has relented a bit this morning and is now predicting a VERY strong ridge over the Central Atlantic and a weaker ridge over the Great Lakes. There is a weakness in between the ridges and IGOR "Shoots the gap". This is really bad news if you like Bermuda to look like a habital island.



The ECMWF shows that same strong ridge in the Central ATL, but it extends it all the way to the Great Lakes ridge and essentially BLOCKS IGOR from going North. This would be bad news if you own Beachfront Property along the central East Coast.



Then there's the GFS. The GFS says YES to that strong ridge in the central ATL. It says the Great Lakes Ridge will be a bit further west and it says there isn't much in between, so IGOR shoots right up north. Bermuda gets a taste of IGOR, but will survive.



Now we get into the "who do you believe" category. Even the NHC forecasters hedge their bets here, talking about "model consensus" and even throwing it back at us to make our own guesses. Check it out! This is from the 5am AST update from the NHC discussion on IGOR:

...ALTHOUGH MOST OF THE GLOBAL MODELS SHOW THE
TROUGH FLATTENING IN 3 TO 4 DAYS...THERE ARE DISAGREEMENTS IN HOW MUCH...IF ANY...SUBTROPICAL RIDGING BUILDS IN THE WAKE OF THE TROUGH. THE ECMWF AND UKMET MODELS CONTINUE TO BUILD MORE RIDGING NORTH OF IGOR...RESULTING IN A TRACK FARTHER WEST THAN THE OTHER MODELS. OVERALL...THE MODEL GUIDANCE HAS SHIFTED SLIGHTLY TO THE RIGHT FROM THE LAST CYCLE AND THE OFFICIAL FORECAST IS NUDGED IN
THAT DIRECTION...BUT REMAINS ON THE SOUTH SIDE OF THE GUIDANCE ENVELOPE.

So, they aren't sure which model to believe either..

The GFS has a historical cold bias for fronts/troughs. They tend to overdo them and their effects. However, the GFS is the only model that properly initializes IGOR's power at the onset. Still, it comes down to those ridges over the Great Lakes and Central ATL. That is the key to IGOR's eventually destination. I doubt anyone here can conclusively tell us as even the models are in disagreement. Perhaps we can get some historical data on flattening troughs and ridging off the NE USA coast by other posters?

My bet is (and this is just a guess....I'm only an amature forecaster....don't hate me) is we are going to have a weakness strong enough to spare the USA east coast. Bermuda on the other hand is still very much in trouble. If I lived on Bermuda, I might want to take that 2 week long vacation to Chicago I've been saving up for.


Excellent analysis. Thanks!
Member Since: Posts: Comments:
.
Member Since: Posts: Comments:
Not to mention women on the blog. :)

REALLY enjoying the idea we are so powerful that we affect your behavior enough to blame us for it, LOL.
Member Since: Posts: Comments:
Troughcasting, and keeping my fingers crossed...
Member Since: Posts: Comments:
4161. luigi18
Quoting stoormfury:
i said it many times before and i will say it again. the trough is too weak for the deepening hurricane Igor. the upper and mid level steering keeps Igor on a west track and the anticipated wnw/nw turn will take longer than the models have forecasted. the northern leewards and PR and the virgin islands should monitorIgor very closely. when the hurricane passes 50W then we we will know how serious the threat of Igor will be


auhch! we are here
Member Since: Posts: Comments:
Quoting Thundercloud01221991:



Actually we are not tied with 2007 we have surpassed 2007

2007:71.7
2010:72.285


Actually--I love it when people say that--for purposes of comparison, ACE is rounded to the nearest whole number. 71.7 = 72; 72.285 = 72.
Member Since: Posts: Comments:
Quoting largeeyes:
Igor sucked in some dry air there....keeping it away from his core, though.
yeah i notices that he suck in a lil bit of dry
Member Since: Posts: Comments:
i said it many times before and i will say it again. the trough is too weak for the deepening hurricane Igor. the upper and mid level steering keeps Igor on a west track and the anticipated wnw/nw turn will take longer than the models have forecasted. the northern leewards and PR and the virgin islands should monitorIgor very closely. when the hurricane passes 50W then we we will know how serious the threat of Igor will be
Member Since: Posts: Comments:
4157. luigi18
Quoting bassis:
And yes, there's ALWAYS a woman to blame...

You better be careful, there's a woman following Igor

like Earl and Fiona
Member Since: Posts: Comments:
Quoting portcharlotte:
It seems like we are in a pattern etched in stone...The maps looks the same they did in late July....The break between highs in the Atlantic which all started with the first re-curve and I believe that contibuted to the lingering weakness there. Also we have the riding over the north Gulf. If this continues you can have 40 storms and they will all miss which is okay but it seems like our luck shoulod run out...any comments

Realistically, we should start focusing our eyes in the Caribbean, where u live & where i live, well we both know too well that Oct. is the month! You had Wilma, & well I was no where in this world yet, but I had 1921 Tampa Bay Hurricane, Wilma, 1921... Wilma, 1921.
Member Since: Posts: Comments:
Quoting Grothar:


SHHH! The westcaster may hear you. I do agree with Storm that it will go a little further west than predicted though, before the turn. Here is a confusing little map, that shows just that.


Stadium effect - check.
Beautiful storm - check.
large eye in comparison to the storm - check?
Member Since: Posts: Comments:
92L firing up t-storm activity.

http://www.ssd.noaa.gov/goes/flt/t2/loop-wv.html

Today may be the day for a TD.
Member Since: Posts: Comments:
4152. bassis
"And yes, there's ALWAYS a woman to blame..."

You better be careful, there's a woman following Igor
Member Since: Posts: Comments:
Igor sucked in some dry air there....keeping it away from his core, though.
Member Since: August 22, 2006 Posts: 0 Comments: 1455
Quoting TropicalAnalystwx13:


Hmmm...Have you tried emailing Jeff himself?


lol.. No never thought of it! thanks ; )
Member Since: Posts: Comments:
4148. bassis
4135. dracko19
Just the facts man,

simple and to the point

thanks
Member Since: Posts: Comments:
Quoting Halon056:


41041 is closest, at last update was still 257 nm away....


Interesting note though, ships report 106 miles away WVHT was 16.4 ft....
Member Since: Posts: Comments:

Viewing: 4196 - 4146

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 | 70 | 71 | 72 | 73 | 74 | 75 | 76 | 77 | 78 | 79 | 80 | 81 | 82 | 83 | 84 | 85Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

Local Weather

Overcast
82 °F
Overcast