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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3696. RyanFSU
GFDL goes east of Bermuda as well. Here's the mash-up of the inner-nest maximum wind speeds: I think people are calling it a fish storm, but I don't think there are that many fish in the central Atlantic (?)

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Quoting JLPR2:


XD

The reality is that 92L is far away form being something, the 850mb vort really weakened today but it's making a comeback, maybe in the next days.

Should be at the Yucatan in a few days.Wed or Thur
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Quoting xcool:
traumaboyy yeahhh

What are ya'll "yelling" and "dooming" about????? Fill me in!
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82 yrs ago, Great Okeechobe's Hurricane, well known as Hurrican San Felipe 2 in Puerto Rico
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3692. xcool
traumaboyy yeahhh
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting CoopNTexas:
gotcha!

@ 384 hours, we all in trouble! LOL
Where are you located? I'm in N Houston
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3690. JLPR2
Quoting F4PHANTOM:
don't let brownsville hear you say that.


XD

The reality is that 92L is far away form being something, the 850mb vort really weakened today but it's making a comeback, maybe in the next days.

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Quoting traumaboyy:


meow don't start in about the donuts again...lol


SmileyCentral.com Fine!
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Quoting xcool:
kaboom we all doom


...we're gonna need a bigger boat!!
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Quoting JLPR2:


haha!
I think 92L is just lazy
don't let brownsville hear you say that.
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Quoting JLPR2:


haha!
I think 92L is just lazy


I prefer a lazy storm myself!!
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3685. xcool
kaboom we all doom
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting StormJunkie:


384hrs is a complete waste of anything except for trying to improve long range forecasting. Can't get better at it if you don't do it...Still worthless for several years to come though.
agree completely just maybe able to get a pattern though
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3683. JLPR2
Quoting traumaboyy:


maybe the water is too hot down there...lol


haha!
I think 92L is just lazy
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3682. 7544
igor likes going west and still is
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gotcha!

@ 384 hours, we all in trouble! LOL
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Quoting JLPR2:
92L looks... sad



maybe the water is too hot down there...lol
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Quoting F4PHANTOM:
at 384hrs


384hrs is a complete waste of anything except for trying to improve long range forecasting. Can't get better at it if you don't do it...Still worthless for several years to come though.
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3678. xcool
JLPR2 .isee hoppe
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting AtHomeInTX:


Awe man I could go for a donut. :)


meow don't start in about the donuts again...lol
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3676. JLPR2
92L looks... sad

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Quoting CoopNTexas:
0z gfs is not TEX/MEX border!

If you think it is, then this state got much bigger! LOL
at 384hrs
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3674. xcool
mmmm donut mmm
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting AtHomeInTX:


:) Hope I'm in here buggin' y'all in the wee hours of the 24th too. (what is it with the night crawlers around here?) Lol. Day or night I hope we all dodge those bullets this year.


hope we are all here....looks like we have finally arrived at the business end of the hurricane season....Hope they all go fishin!!
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Why haven't they put the Goes 15 science test on Igor yet...Bummer.
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3671. JLPR2
Quoting StormJunkie:


If that is the trough in the upper right, it looks like it started to dive down, but seems to flatten as some have mentioned as a possibility in the last portions of that loop.

Not saying that means Igor won't still curve, but it's interesting to see that feature flatten out. Any experts want to chime in?


I second that!
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0z gfs is not TEX/MEX border!

If you think it is, then this state got much bigger! LOL
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3669. xcool
traumaboyy lmaooo
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting JLPR2:
Igor says: What weakness?

It hasn't felt the trof



If that is the trough in the upper left, it looks like it started to dive down, but seems to flatten as some have mentioned as a possibility in the last portions of that loop.

Not saying that means Igor won't still curve, but it's interesting to see that feature flatten out. Any experts want to chime in?
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3667. JLPR2
Expect the ring of convection to be back in full force once the satellites update, Eumetsat shows it is back now.

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Quoting traumaboyy:
Good morning Night shift....Hot coffee and cream cheese bagels are ready!!


Awe man I could go for a donut. :)
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3665. xcool
hmm
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting xcool:
traumaboyy heyy ..god i'm nott ready for workkk


you are breakin my heart....I have been at work six hours and we be buzy tonight!!
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Quoting traumaboyy:


Amen!!


:) Hope I'm in here buggin' y'all in the wee hours of the 24th too. (what is it with the night crawlers around here?) Lol. Day or night I hope we all dodge those bullets this year.
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3662. RyanFSU
The initialization of HWRF was atrocious. Gah, look at the evolution after 6-hours, poof! Many problems with this: wind/pressure balance askew, environment prescription from the boundary GFS out of whack... all very technical terms of course.



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XCOOL looked at different 00z gfs. not heading N but same as all rest this season, Tex/Mex border
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3660. xcool
traumaboyy heyy ..god i'm nott ready for workkk
Member Since: September 26, 2009 Posts: 2 Comments: 15684
3659. JLPR2
Igor says: What weakness?

It hasn't felt the trof

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Good morning Night shift....Hot coffee and cream cheese bagels are ready!!
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3657. xcool
CoopNTexas/ Allan Huffman's websitess CMC 240 Long range
Member Since: September 26, 2009 Posts: 2 Comments: 15684
CMC 240 Long range

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Quoting AtHomeInTX:
this time 3 years ago...



This time 2 years ago...



How happy am I to be sitting snug in my bed right now!! :)


Amen!!
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3654. JLPR2
Igor is slightly bigger now and the eye is no longer round, looks like a sideways triangle. XD

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Mail PSL. I should never have even looked at the 70-200 2.8 IS-II...Ughh

And once again to stay on topic...Igor is still out there...

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3652. xcool
iwaitting for cmc long range model come outt soon
Member Since: September 26, 2009 Posts: 2 Comments: 15684
this time 3 years ago...



This time 2 years ago...



How happy am I to be sitting snug in my bed right now!! :)
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Quoting xcool:


cmc on now too

PGI45L

higher lat than GFS and already developed
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Quoting JP2010:


This is the best lens i have ever used a lot storm photos. This lens is not 70-200 L is great lens high recommend it.
Sorry, not quite sure what you're saying. Clarification?
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3648. Ryuujin
Quoting JP2010:


This is the best lens i have ever used a lot storm photos. This lens is not 70-200 L is great lens high recommend it.


What kind of lens, and what kind of camera?
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cmc

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3646. Ryuujin
Thanks, but that was quite a few years ago now. To be honest, it was just all of a sudden and poof. It was only about 3 miles from where my sister lived. Crazy stuff.
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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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