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: 2746 - 2696

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

Quoting MississippiBoy:
hey don't want anything to do with Igor,I remember Ivan.

IGOR, the IVAN comrade
Member Since: Posts: Comments:
2744. mbjjm
Igor no concern for the Islands. Igor is already at the latitude of the Islands while over 1000 miles away, will gain latitude and keep at least 400 miles north. Could directly impact Bermuda
Member Since: Posts: Comments:
2743. angiest
Quoting Goldenblack:
The west African system still on land looks mighty threatening and ominous. Hope that pattern change doesn't occur (MJO moving toward our quadrant) before that thing gets mid ATL.



GFS has not been developing that, at least not near Africa.
Member Since: Posts: Comments:
Quoting Vero1:


You can watch them on Google Earth. You can also watch the GRIP Global Hawk and DC-8 which are also flying in the same area on RTMM Classic on Google Earth.


I am on Google Earth but not sure where you find this information. Is there something I need to click on under layers?
Member Since: Posts: Comments:
Quoting mbjjm:


Earl was further South, Igor already at 17N well north of the Islands

the northernmost islands is Anguilla at around 18.5 N
Member Since: Posts: Comments:
Link

Is Igor located in 18 and 47? Please check the latest satellite pic.
Member Since: Posts: Comments:
The west African system still on land looks mighty threatening and ominous. Hope that pattern change doesn't occur (MJO moving toward our quadrant) before that thing gets mid ATL.

Quoting Hhunter:


oh man..
Member Since: Posts: Comments:
2738. pottery
Heh!!
We are in for some pretty Scary stuff.
That storm over Africa is as big as Igor already....
Member Since: Posts: Comments:
Quoting Ameister12:
I think Igor want's to be like his companion, Ivan.
hey don't want anything to do with Igor,I remember Ivan.
Member Since: Posts: Comments:
Quoting MiamiHurricanes09:
About a 90% chance that you will...if it isn't a category 5 by the time you head out.

Just so you know, I'll be at school from 7:30AM to 3 or 4:30 PM tomorrow, Tuesday and Thursday. So I'll miss a lot of information :(
Member Since: Posts: Comments:
Quoting Hhunter:


oh man..


Holy crap man that blob over Africa looks better than most TS
Member Since: Posts: Comments:
Quoting Flyairbird:
Right?...that look like it covers a few countries in africa
If that thing comes this way we had better all run for the hills!!!
Member Since: Posts: Comments:
Agree...still intensifying...even though there is just a hint of dry air "fight" in the NW quadrant...

Anyone want to speculate on the amount of time we might see this WSW motion continue? Looking at the WV and deep steering currents as posted by Levi, looks like this might be more than a wobble occurring.

Quoting MiamiHurricanes09:
Look at that clear and contracting eye. Still an intensifying hurricane.
Member Since: Posts: Comments:
2731. Hhunter


oh man..
Member Since: August 19, 2007 Posts: 0 Comments: 2973
2730. hercj
Quoting Levi32:


The next pull will be the shortwave currently coming off the eastern seaboard.

Levi, what is your take on 92L? Everything is right but it just won't fire.
Member Since: Posts: Comments:
Quoting Chicklit:
If Igor goes annular all bets are off.
Night folks. It's been an unsettling day.

And what the heck is that blob over Africa?!

good grief.


Good Lord man...that things looks bigger than most countries
Member Since: Posts: Comments:
Quoting MiamiHurricanes09:
ADT up to T6.8 which would indicate a pressure of 928.6mb and winds of 135kt (155mph).

2010SEP13 004500 6.8 928.6/ +2.0 /134.8


Wilma intensified 55 knots in 12 hours,Igor-50 knots in 12 hours,amazing considering the fact that Igor is east of 50w.
Member Since: Posts: Comments:
2727. mbjjm
NOgaps and CMCI Both outliers, both turn Igor away forom the US.
Member Since: Posts: Comments:
Quoting Stormchaser2007:
WOW

ADT suggests 155 now.


Wow. How strong is this sucker going to get?
Member Since: Posts: Comments:
Quoting Ameister12:
I think Igor want's to be like his companion, Ivan.
Look at that clear and contracting eye. Still an intensifying hurricane.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
2724. breald
Quoting Levi32:


1. Yes.

2. Igor is nearly annular, which means he has a structure that is highly resistant to EWRCs. In other words, unless he is exposed to a negative factor (dry air, wind shear, cold water), he likely won't undergo an EWRC. He will simply remain this way, either annular or nearly annular, and maintain a nearly constant intensity once he peaks, with minor fluctuations until he begins recurving. Hurricane Isabel in 2003 trekked for days across the Atlantic at Cat 4/5 intensity with little change in structure when she was annular, with no EWRCs.


so an annular storm still stays on the projected track?
Member Since: Posts: Comments:
Quoting Stormchaser2007:
WOW

ADT suggests 155 now.
1mph shy of category 5.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting winter123:
WSW. Islands need to be alert still.

Link


Looks due west to me. However, if I lived on the islands I would still be watching very closely.
Member Since: Posts: Comments:
I think Igor want's to be like his companion, Ivan.
Member Since: Posts: Comments:
WOW

ADT suggests 155 now.
Member Since: June 9, 2007 Posts: 4 Comments: 15920
Quoting MiamiHurricanes09:
ADT up to T6.8 which would indicate a pressure of 928.6mb and winds of 135kt (155mph).

2010SEP13 004500 6.8 928.6/ 2.0 /134.8

Just short of a Cat5. Still has two hours till the advisory.
Member Since: Posts: Comments:
2718. Seastep
CybrTeddy - do you have the link to the model error? I thought it was you and I can't find it through normal searching. TIA.
Member Since: Posts: Comments:
2717. mbjjm
Quoting winter123:
WSW. Islands need to be alert still.

Link


just a wobble, Wobbles and eye replacements common with intense systems
Member Since: Posts: Comments:
Link

Cann anyone tell me where the center is located?
Member Since: Posts: Comments:
Quoting KATRINABILOXIGIRL:
Looks like Igor's scary big uncle Frankenstein!!!
Right?...that look like it covers a few countries in africa
Member Since: Posts: Comments:
Quoting WeatherNerdPR:

What are the odds of me waking up to a Cat5?
About a 90% chance that you will...if it isn't a category 5 by the time you head out.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
2713. Levi32
Quoting doorman79:


Also, where is the "pull" north on there?


The next pull will be the shortwave currently coming off the eastern seaboard.
Member Since: Posts: Comments:
Quoting Chicklit:
If Igor goes annular all bets are off.
Night folks. It's been an unsettling day.

And what the heck is that blob over Africa?!

good grief.
Looks like Igor's scary big uncle Frankenstein!!!
Member Since: Posts: Comments:
google earth maps now has igor with winds of 150 mph 10 pmh shy of cat 5 however another right shift in the 3-5 day track is likely at 11 pm
Member Since: Posts: Comments:
2709. Levi32
Quoting GeoffreyWPB:


That steering would also take 92L westward in the long term. Correct?


If it were to remain static, yes, but steering isn't static. I don't think Igor will gain any significant latitude before 60W. In other words, the recurve won't be really beginning until after that point.
Member Since: Posts: Comments:
Quoting WeatherNerdPR:

What are the odds of me waking up to a Cat5?


Likely.
Member Since: Posts: Comments:
Quoting Chicklit:
If Igor goes annular all bets are off.
Night folks. It's been an unsettling day.

And what the heck is that blob over Africa?!

good grief.

perhaps KARL
Member Since: Posts: Comments:
Quoting Levi32:


That would make sense. It is reflected in the deep-layer steering as well.



Also, where is the "pull" north on there?
Member Since: Posts: Comments:
WSW. Islands need to be alert still.

Link
Member Since: Posts: Comments:
Quoting MiamiHurricanes09:
Satellite imagery reveals that Igor's eye is contracting and getting better defined while jogging slightly towards the WSW.

What are the odds of me waking up to a Cat5?
Member Since: Posts: Comments:
ADT up to T6.8 which would indicate a pressure of 928.6mb and winds of 135kt (155mph).

2010SEP13 004500 6.8 928.6/ 2.0 /134.8
Member Since: September 2, 2009 Posts: 130 Comments: 21194
2702. JLPR2
Quoting mbjjm:


Earl was further South, Igor already at 17N well north of the Islands


PR and the Virgin islands are at 18N so I dont know of what islands you're talking about.
Member Since: Posts: Comments:
Quoting mbjjm:


None of the models take Igor near the US.
Computers

Check CMCI and NGPS.
Member Since: Posts: Comments:
2700. hercj
Quoting angiest:


What's the farthest east they do recon?

The NCAR GV can go all the way to 40W. The low level P3's and the 130J's only to 55W
Member Since: Posts: Comments:
Quoting Chicklit:
If Igor goes annular all bets are off.
Night folks. It's been an unsettling day.

And what the heck is that blob over Africa?!

good grief.
What in the world is that huge mess over africa in that pic.?
Member Since: Posts: Comments:
2698. will40
Quoting Hurricanes101:


Igor is too far east for them to do recon on, has nothing to do with not being concerned


yea at current speed it will be tuesday before they can go in
Member Since: September 19, 2005 Posts: 2 Comments: 4251
Link

This is Igor one of the last satellite photos, can anyone tell me where is the center located?
Member Since: Posts: Comments:
That blob over
Quoting Chicklit:
If Igor goes annular all bets are off.
Night folks. It's been an unsettling day.

And what the heck is that blob over Africa?!

good grief.


That blob over Afirca make Igor look like an invest
Member Since: Posts: Comments:

Viewing: 2746 - 2696

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.