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: 3996 - 3946

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 StormW:


I'll try to do a graphic once I finish my synopsis. Basically, what I'm saying is...I believe he will be further west than indicated before he makes a "good" turn


Thanks in advance. The setup is interesting...
Member Since: Posts: Comments:
Quoting LPstormspotter2:
Good Morning! I have been coming here for a few yrs but my computer crashed and i for my password i have email WU Admin a few times but they havent sent password.. Any Idea's?

Also last night on local news 13 houston said we needed to watch 92L but only as a rain maker.
Member Since: Posts: Comments:
There'll be a lull in activity at some point.

It's just at what point and where we are at when it occurs.
Member Since: Posts: Comments:
3989. KEEPEROFTHEGATE (Mod)
011L/MH/I/C4
MARK
17.85N/49.35W


Member Since: Posts: Comments:
I could see between Igor and Julia... ACE getting to 110 that is only 20 more for each of the storms... Igor it is a given he will likely get 20 more and I think that Julia will as well because it will be a long track storm... we then have a system from 92L that may develop and give us 5-10 ACE and we have another potential storm that will emerge off of Africa in 2-3 days that if it would develop would likely be a long tracker... I still think we could see 180 ACE for the season
Member Since: Posts: Comments:
3987. MahFL
I too am waiting on the so called pattern change, or did it not happen as many forcast it would ?
Member Since: Posts: Comments:
3985. IKE
Look at Climatology maps. It will tell you where storms have originated in the coming weeks, in the last 158(1851-2009) years....





Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting StormW:


Where?

Did you see this Storm?



So if I'm reading this correctly it should start making that turn later today.
Member Since: Posts: Comments:
I think now that any "turn" we are seeing is just a wobble - I was fooled by it too. Igor is going west and I think he's going much further west before making any dramatic turn to the north.
Member Since: Posts: Comments:
One word, spectacular...
Round eye, I'm awestruck...
Member Since: Posts: Comments:
3981. MahFL
3951.

The NHC forcast west, then wnw, then NW. Not what you say.
Member Since: Posts: Comments:
Quoting StormW:


You're kidding, right?


I have read that we are supposed to see stronger HP's with less troughs allowing these CV storms to become more of a threat to the EC.
Member Since: Posts: Comments:
Quoting Cotillion:


Every hour would be a bit much.

That'd mean he'd be 1.638 or so every hour. That'd mean per advisory he'd be 9.828.

To put that into perspective, only a 200mph super-Category Five can get over 3 in ACE per 6 hours.

If you mean per 6 hour advisory, then yes, that's correct.

150mph is 1.6900 in ACE.

ACE Tutorial


it would only have to be a 315 knt superstorm to get 9.9225 ACE per advisory
Member Since: Posts: Comments:
Quoting wxhatt:


good thing they are forcast to be with the fishies!


I think it would be a little tough to forecast the long-range track of some blob that hasn't even exited the African coast.
Member Since: Posts: Comments:
Quoting RecordSeason:
3963:

Yeah, someone said yesterday that every hour for Igor's ACE was the equivalent of Hermine and Gaston's entire combined existence in ACE.


Every hour would be a bit much.

That'd mean he'd be 1.64 or so every hour. That'd mean per advisory he'd be 9.84.

To put that into perspective, only a 200mph super-Category Five can get over 3 in ACE per 6 hours.

If you mean per 6 hour advisory, then yes, that's correct.

150mph is 1.6900 in ACE.

ACE Tutorial
Member Since: Posts: Comments:
3974. tkeith
Well it appears that the prognosticators of an above average season (18 named storms) may not get burned at the stake after all.

Member Since: Posts: Comments:
Quoting StormW:


I'll try to do a graphic once I finish my synopsis. Basically, what I'm saying is...I believe he will be further west than indicated before he makes a "good" turn


Good morning, Chief. I really enjoyed listening to you on BB last night. What a learning experience. Thank you!
Member Since: Posts: Comments:
So when is this big pattern change supposed to happen and keeps storms moving more W?
Member Since: Posts: Comments:
Quoting AstroHurricane001:


GFS consistently predicted (for 36 hours) a hurricane in the Gulf or one moving from the Caribbean toward the East Coast by the end of the run. This time it shows two components.

Looks to stay active last half of the month, ay.
Member Since: Posts: Comments:
3968. wxhatt
Quoting GTcooliebai:
Check out what's behind Julia!



good thing they are forcast to be with the fishies!
Member Since: Posts: Comments:
Check out what's behind Julia!

Member Since: Posts: Comments:
Quoting aislinnpaps:
So if Igor gets past 50 to 55, it's missed the second trough, correct?


My guess is we're in threading the needle territory again anywhere past 70W, pretty much like Earl.
Member Since: Posts: Comments:
Geoffrey is right up the road from me... here in Boca. Small weather world. I'll sigh relief when I see Igor really start heading north.
Member Since: Posts: Comments:
By the way as of the Advisory at 5 AM ... 2010 has passed 2007 in terms of ACE
Member Since: Posts: Comments:
3962. tkeith
Quoting FLdewey:
Phish food is my favorite Ben & Jerry's flavor.
Jasons too...
Member Since: Posts: Comments:


GFS consistently predicted (for 36 hours) a hurricane in the Gulf or one moving from the Caribbean toward the East Coast by the end of the run. This time it shows two components.
Member Since: Posts: Comments:
3960. Buzzit
Looking at the latest loops I cannot see any NW motion trend any time soon (and yes you can start to see a very little bit of dry air getting entrained into Igors extreme NW band in the attached link)

http://www.ssd.noaa.gov/goes/east/nwatl/flash-wv.html
Member Since: Posts: Comments:
So if Igor gets past 50 to 55, it's missed the second trough, correct?
Member Since: Posts: Comments:
Quoting LPstormspotter2:


Under the log in is forgot my password. I have tried a few times. You put your email address in and they send the password.. Anyway guess its not that big of a deal i just have to start over. lol.
Are You still using the old computer or the new one? How are you posting here now?
Member Since: Posts: Comments:
Member Since: Posts: Comments:
here comes the turn
Member Since: Posts: Comments:
3952. IKE
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT MON SEP 13 2010

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON HURRICANE
IGOR...LOCATED ABOUT 940 MILES EAST OF THE NORTHERN LEEWARD ISLANDS
...AND ON TROPICAL STORM JULIA...LOCATED ABOUT 85 MILES
WEST-SOUTHWEST OF THE SOUTHERNMOST CAPE VERDE ISLANDS.

A TROUGH OF LOW PRESSURE OVER THE CENTRAL CARIBBEAN SEA CONTINUES TO
PRODUCE DISORGANIZED CLOUDINESS AND SHOWERS. ENVIRONMENTAL
CONDITIONS APPEAR TO BE CONDUCIVE FOR SOME DEVELOPMENT DURING THE
NEXT COUPLE OF DAYS AS THE TROUGH MOVES WEST-NORTHWESTWARD AT
AROUND 15 MPH. THERE IS A MEDIUM CHANCE...40 PERCENT...OF THIS
SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.
REGARDLESS OF DEVELOPMENT...LOCALLY HEAVY RAINFALL IS POSSIBLE OVER
PORTIONS OF HISPANIOLA...JAMAICA...CUBA...AND THE CAYMAN ISLANDS
DURING THE NEXT DAY OR TWO. THESE RAINS COULD CAUSE
LIFE-THREATENING FLASH FLOODS AND MUD SLIDES...ESPECIALLY IN
MOUNTAINOUS TERRAIN.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

PUBLIC ADVISORIES ON JULIA ARE ISSUED UNDER WMO HEADER WTNT32 KNHC
AND UNDER AWIPS HEADER MIATCPAT2. FORECAST/ADVISORIES ARE ISSUED
UNDER WMO HEADER WTNT22 KNHC AND UNDER AWIPS HEADER MIATCMAT2.

$$
FORECASTER BRENNAN

Member Since: June 9, 2005 Posts: 23 Comments: 37858
Boy if high pressure sets up in the Atlantic Watch Out!

Member Since: Posts: Comments:
Igor soon to become a cat. 5, before moving into waters with SSTs higher than 29C. Annular hurricanes typically need water COOLER than 28.5C to maintain their structure.
Member Since: Posts: Comments:
Quoting edmac:
Anyone out there think Igor will follow the type track as Earl.



Its within the realm of possiblity. I won't speculate on odds tho.
Member Since: Posts: Comments:
Quoting Thundercloud01221991:


Have you used the forgot my password page?


Under the log in is forgot my password. I have tried a few times. You put your email address in and they send the password.. Anyway guess its not that big of a deal i just have to start over. lol.
Member Since: Posts: Comments:
Quoting RecordSeason:
3891:

Um...yes...

It moved with a slight southerly drift for most of yesterday, having moved somewhere between 0.1 to 0.15 degrees south in a 7 hour period. Check the storm history on WU page.


As I just said, we are very fortunate the peak in the ridge retreated. The steering map last night was indicative of a course change to ~245 degrees heading.


The question is did the ridge retreat or did the environment Igor's created around himself push it right out of the way?

Morning everyone. Wow. Igor is one of the most beautiful TCs I've seen in years.
Member Since: Posts: Comments:

Viewing: 3996 - 3946

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.