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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The wave behind TD12 looks pretty vigorous this evening. It's looked pretty impressive all day. Reminds me of TS Christina (1972 I believe, but I could be off). It was designated a TD while still over Africa. The only one to do so if I remember correctly.
Member Since: Posts: Comments:
Igor was 75 mph at 11pm yesterday.

Now it will be 150mph.

Amazing.
Member Since: Posts: Comments:
Quoting stormwatcherCI:
Yes.
Link Go to this link and find the mission then save it to your google earth settings
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Quoting DESteve:
StormW sharing his comments with BarometerBob @ irc.hurricanehollow.org
Thanks Steve
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Igor has the potential for some nice ACE numbers. This season has a very real chance to be dubbed hyperactive, even after the "slow start."
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If Igor continues to be a monster I could easily see Category 5 at 11 pm. Just 6 mph short.
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2539. BDADUDE
You guys are actually starting to make me think that we Bermudians actually have something to worry about.
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2538. Vero1
Quoting LightningCharmer:
'See it as well but not real clear.


A 1007 MB SURFACE LOW S OF HAITI NEAR
16N72W
Member Since: July 21, 2008 Posts: 4 Comments: 2233
2537. DESteve
StormW sharing his comments with BarometerBob @ irc.hurricanehollow.org
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Quoting Stormchaser2007:


150 mph officially.

Wow.
I bid 160.... Wow things are picking up
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Quoting weatherwatcher12:

Recon found some SSW winds.
What does this mean ? Does it have a closed circulation ?
Member Since: October 9, 2008 Posts: 0 Comments: 8436
Great Scott!
11, 2010091300, , BEST, 0, 177N, 473W, 130, 935, HU

150 mph, 935 mb.
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2533. Max1023
Quoting MiamiHurricanes09:
AL, 11, 2010091300, , BEST, 0, 177N, 473W, 130, 935, HU,


That's from 8pm EDT. That's 10 knots of strengthening in 3 hours. If that continues at 11 we will have a Cat 5.
Member Since: July 22, 2008 Posts: 1 Comments: 286
Quoting dmaddox:
ANY sign of Igor weakening!??


No all systems are go for Igor the Terrible.
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Quoting Drakoen:
Igor probably on the verge of becoming a Category 5 Hurricane.


150 mph officially.

Wow.
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Quoting TampaSpin:
Sure looks on Satellite that a Closed Surface Low is developing to me on 92L

Recon found some SSW winds.
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Tropical Storm JULIA.

AL, 12, 2010091300, , BEST, 0, 133N, 229W, 35, 1005, TS

10-4-3.

7 more to my prediction. Very probable.

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Quoting TampaSpin:
Sure looks on Satellite that a Closed Surface Low is developing to me on 92L
'See it as well but not real clear.
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ATCF says the winds have risen to 150mph and that the pressure has dropped to 935mb.

AL, 11, 2010091300, , BEST, 0, 177N, 473W, 130, 935, HU,
Member Since: September 2, 2009 Posts: 130 Comments: 21194


Here we go again.
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What do you think the chances of Igor getting to Cat5 statis are?
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2524. Seastep
Quoting jlp09550:


Visible of Igor?


Yes. Sorry... kids to bed. :)
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2523. Max1023
Quoting Krycek1984:
And how can Igor be so strong and well organized when it's ramming right into all that dry air?


It isn't, the dry air is being displaced by the moist air of Igor's circulation. Look at MIMIC Precip. water.
Member Since: July 22, 2008 Posts: 1 Comments: 286
Quoting belizeit:
Do you have google earth on your computer
Yes.
Member Since: October 9, 2008 Posts: 0 Comments: 8436
2520. Vero1
Quoting stormwatcherCI:
Can you please show me how you know this ?


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.
Member Since: July 21, 2008 Posts: 4 Comments: 2233
2518. Drakoen
Igor probably on the verge of becoming a Category 5 Hurricane.
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Quoting sunlinepr:
Sorry, Julia is on the way....



Okey dokey, but until they name it, it's TD12, 92L, "look that that next wave!" or whatever.
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Quoting Krycek1984:
And how can Igor be so strong and well organized when it's ramming right into all that dry air?


the dry air is moving ahead of the system
Member Since: March 10, 2010 Posts: 1 Comments: 7874
2515. JLPR2


Quite impressive and TD looks like a Julia already.

*I hate the SDD images! :|
Keeps going back in time after they update.
Member Since: September 4, 2007 Posts: 7 Comments: 8747
Quoting dracko19:
The GFS and GFDL predict IGOR makes a direct hit on Bermuda. The NOGAPS predicts a very close encounter. The SHIPS intensity model has this storm approaching Cat 5.

Bermuda was so nice too. Maybe we should grab some "BEFORE" pictures if these models are correct. Has a Cat 5 ever hit Bermuda??







How can it reach Cat 5 that far north with all the upwelling of cool water from Danielle?
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2513. dmaddox
Quoting dracko19:
The GFS and GFDL predict IGOR makes a direct hit on Bermuda. The NOGAPS predicts a very close encounter. The SHIPS intensity model has this storm approaching Cat 5.

Bermuda was so nice too. Maybe we should grab some "BEFORE" pictures if these models are correct. Has a Cat 5 ever hit Bermuda??





this is so sad :(
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NHC forecast brings it up to 135 kt, which is basically a cat. 5 hurricane.



Houston, we have an annular.



This is Hurricane Isabel, on September 9, 2003, at roughly the same location as Igor is now. Isabel at that time was weaker than Igor, and hadn't even started to become annular yet, and its eye had not become well-developed yet although its size was similar. The question is, what will Igor do with its intensity, with waters all along its path warmer than it was in 2003, now that it's already a cat. 4, and rapidly strengthening?

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2510. Max1023
Quoting jurakantaino:
Well I remember and old met from the past said, follow the clouds to tell the track, but that would be the worst case scenario for the NE caribbean and CONUS.


That only applies for short term (<24 hour) tracks. Beyond that the cloud motion would likely change due to evolving synoptic conditions.
Member Since: July 22, 2008 Posts: 1 Comments: 286
ok guys I just came back from my uncle's B'day party anyone and everyone give me an update thank you
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And how can Igor be so strong and well organized when it's ramming right into all that dry air?
Member Since: Posts: Comments:
The GFS and GFDL predict IGOR makes a direct hit on Bermuda. The NOGAPS predicts a very close encounter. The SHIPS intensity model has this storm approaching Cat 5.

Bermuda was so nice too. Maybe we should grab some "BEFORE" pictures if these models are correct. Has a Cat 5 ever hit Bermuda??





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2506. dmaddox
ANY sign of Igor weakening!??
Member Since: Posts: Comments:
Quoting stormwatcherCI:
Can you please show me how you know this ?
Do you have google earth on your computer
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AL, 12, 2010091300, , BEST, 0, 133N, 229W, 35, 1005, TS

atcf says Julia at 11pm
Member Since: March 10, 2010 Posts: 1 Comments: 7874
love how record global temps (land & sea) have zero effect on hurricanes. Other factors do come into play, i.e. shear, SAL, etc, but heat = energy. Basic high school science.

Why don't we argue if we can boil an egg without turning on the stove?

common sense not so common.
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Quoting sunlinepr:
Notice that small cloud area at 58W 20N, still moving west.... It seems Igor should reach this area until it begings feeling the trough. Meanwhile it keeps loyal to 17-18N....

Well I remember and old met from the past said, follow the clouds to tell the track, but that would be the worst case scenario for the NE caribbean and CONUS.
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2500. Vero1
Quoting stormwatcherCI:
Can you please show me how you know this ?


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.
Member Since: July 21, 2008 Posts: 4 Comments: 2233
2499. Max1023
According to SSD raw numbers have supported Category 5 (T# 6.9 or higher) for an hour now.
Member Since: July 22, 2008 Posts: 1 Comments: 286
Sure looks on Satellite that a Closed Surface Low is developing to me on 92L
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2497. angiest
Quoting TexasHurricane:


indeed......


Always.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
Looks like some dry shear is coming from the east upsetting 92L. The Caribbean isn't usually this dry is it?
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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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