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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2146. sunlinepr
11:12 PM GMT on September 12, 2010
Hey Taxi, pick up Igor.... Going WNW???
Hey Taxi, taxi.....

Member Since: August 2, 2010 Posts: 21 Comments: 9882
2145. weathermancer
11:12 PM GMT on September 12, 2010
Quoting Patrap:
Now Im going out to get a Dozen Krispy Kreme fo sho..


Have you tried their new Annular Donuts.

Member Since: August 29, 2009 Posts: 12 Comments: 483
2144. Vero1
11:12 PM GMT on September 12, 2010
Both the GRIP DC-8 and the GLOBAL HAWK are currently flying over the Carib. in 92L and in the area of convection south of Haiti.
Member Since: July 21, 2008 Posts: 4 Comments: 2233
2143. MiamiHurricanes09
11:12 PM GMT on September 12, 2010
Quoting kmanislander:


Near 16 / 73
Thank you.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
2142. dracko19
11:12 PM GMT on September 12, 2010
Is it time to start talking ATL records with IGOR?

Pressure: 882 - Wilma (2005)
Wind Speed: 190 - Allen (80) and Camille (69)

IGOR has a way to go...or does he? Wonder if we'll ever know without a Hunter in there.
Member Since: September 21, 2005 Posts: 2 Comments: 310
2141. dmaddox
11:12 PM GMT on September 12, 2010
Quoting Stormchaser2007:
Most impressive hurricane I've seen in a while.

Heck, maybe since Dean or Felix.
WOW
Member Since: May 5, 2007 Posts: 0 Comments: 445
2140. bird72
11:12 PM GMT on September 12, 2010
Quoting StormW:
Good evening!

Storm, if is possible, can you tell us a comment about the trof that are forecasted to bring Igor in a nw track? They are behaving like forecasted or no? and the highs how you see them?
Member Since: August 5, 2009 Posts: 0 Comments: 389
2139. kmanislander
11:12 PM GMT on September 12, 2010
Quoting MiamiHurricanes09:
Kman, sorry if you already stated this and I missed it, but where do you have 92L's circulation?


Near 16 / 73
Member Since: August 19, 2006 Posts: 0 Comments: 15948
2138. Max1023
11:11 PM GMT on September 12, 2010
Quoting Stormchaser2007:
Most impressive hurricane I've seen in a while.

Heck, maybe since Dean or Felix.


That looks better than dean did except for right before landfall when he was 905mb. Igor is not as large but has a stronger core. Imagine what Igor would have been like if he went through the NW carribean.
Member Since: July 22, 2008 Posts: 1 Comments: 286
2137. all4hurricanes
11:11 PM GMT on September 12, 2010
Quoting TropicalAnalystwx13:
Poll time!

Is Igor currently a Category 5 Hurricane?

A. Yes
B. No

Will the NHC send out a Special Advisory to upgrade him to a Category 5?

A. Yes
B. No

I say A B

Not currently but before 11 maybe even 8, NHC won't admit he's a five until reanalysis and he meets most if not all requirements for being annular, 92L I think will be a TD at 11. There, I think I nailed every pole
Member Since: March 29, 2008 Posts: 0 Comments: 2375
2136. MiamiHurricanes09
11:11 PM GMT on September 12, 2010
Kman, sorry if you already stated this and I missed it, but where do you have 92L's circulation?
Member Since: September 2, 2009 Posts: 130 Comments: 21194
2135. SouthDadeFish
11:11 PM GMT on September 12, 2010
Quoting MiamiHurricanes09:
Here. Just click on "11L" to access the latest data for Igor.
Thanks a ton! Updates faster than CIMSS...
Member Since: August 12, 2007 Posts: 11 Comments: 2448
2134. kmanislander
11:11 PM GMT on September 12, 2010
Quoting stormwatcherCI:
Any possibility this is already a TD ?


I doubt it. The 850 vort is not well defined and it does not have the appearance of a TD to me.
Member Since: August 19, 2006 Posts: 0 Comments: 15948
2133. Jedkins01
11:11 PM GMT on September 12, 2010
Quoting StormW:


No.



gosh what is it with people in here and annular hurricanes? They are very rare, just because Igor is very intense and well organized does not make in annular. Dang.
Member Since: August 21, 2008 Posts: 0 Comments: 7951
2132. TOMSEFLA
11:11 PM GMT on September 12, 2010
p3 noaa recon passing over sw haiti. sould get some good info during the next three hours.
Member Since: October 19, 2005 Posts: 0 Comments: 234
2130. dmaddox
11:11 PM GMT on September 12, 2010
Quoting MiamiHurricanes09:
Here. Just click on "11L" to access the latest data for Igor.
thx!
Member Since: May 5, 2007 Posts: 0 Comments: 445
2128. Stormchaser2007
11:10 PM GMT on September 12, 2010
Most impressive hurricane I've seen in a while.

Heck, maybe since Dean or Felix.
Member Since: June 9, 2007 Posts: 4 Comments: 15947
2127. Walshy
11:10 PM GMT on September 12, 2010
Quoting StormW:


No.



Thanks!

I thought I was going crazy there for a moment. I thought the banding features shortened when Igor went from a CAT1 to CAT4 based on the Docs image at the top.
Member Since: May 17, 2009 Posts: 2 Comments: 904
2126. Hhunter
11:10 PM GMT on September 12, 2010
Member Since: August 19, 2007 Posts: 0 Comments: 2974
2125. flaghostrider
11:10 PM GMT on September 12, 2010
Member Since: September 9, 2007 Posts: 0 Comments: 5
2124. doorman79
11:10 PM GMT on September 12, 2010
Quoting Patrap:
Now Im going out to get a Dozen Krispy Kreme fo sho..


All the way to west meterie and clearview?
Member Since: August 11, 2010 Posts: 0 Comments: 895
2123. weathermancer
11:09 PM GMT on September 12, 2010
Quoting sunlinepr:
AFRICA IS ALIVE....



Beautiful image.
We are all one.
Thanks for posting!
Member Since: August 29, 2009 Posts: 12 Comments: 483
2122. kabloie
11:09 PM GMT on September 12, 2010
Category 1, 2, 4!

Three sir!
Member Since: November 16, 2002 Posts: 1 Comments: 82
2121. BDAwx
11:09 PM GMT on September 12, 2010
interesting thing is that Ivan was alive and well the same time 6 years ago and Igor replaced Ivan on the naming list.
Member Since: August 3, 2009 Posts: 51 Comments: 545
2120. Hurricanes101
11:09 PM GMT on September 12, 2010
Quoting StormW:


No.


If he is not annular I think he may be trending that way
Member Since: March 10, 2010 Posts: 1 Comments: 7874
2119. Hhunter
11:08 PM GMT on September 12, 2010


folks..92l looking better..bigger current conus threat....
Member Since: August 19, 2007 Posts: 0 Comments: 2974
2118. MiamiHurricanes09
11:08 PM GMT on September 12, 2010
Quoting SouthDadeFish:
Hey Miami,

Can I please get a link to where you're getting this from?
Here. Just click on "11L" to access the latest data for Igor.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
2117. hydrus
11:08 PM GMT on September 12, 2010
Igor continues to organize as shown by the Dvorak pic. .it is power
Member Since: September 27, 2007 Posts: 1 Comments: 22252
2116. Stormchaser2007
11:08 PM GMT on September 12, 2010
Member Since: June 9, 2007 Posts: 4 Comments: 15947
2112. dmaddox
11:07 PM GMT on September 12, 2010
Quoting RecordSeason:
I haven't seen anything like this in the Atlantic since Felix and Dean.

need to get that light grey wrapped all the way around! ;)
Member Since: May 5, 2007 Posts: 0 Comments: 445
2111. SouthDadeFish
11:07 PM GMT on September 12, 2010
Quoting MiamiHurricanes09:
RAW T# up to 6.9.

2010SEP12 224500 6.6 934.2/ +2.0 /129.6 6.6 6.8 6.9 3.2T/18hr OFF OFF 15.44 -71.02 EYE 26 IR 17.66 46.90 COMBO
Hey Miami,

Can I please get a link to where you're getting this from?
Member Since: August 12, 2007 Posts: 11 Comments: 2448
2110. btwntx08
11:07 PM GMT on September 12, 2010
false
Member Since: July 13, 2008 Posts: 6 Comments: 10796
2109. Kristina40
11:06 PM GMT on September 12, 2010
Quoting StormW:
Good evening!


Just in time Storm, it was starting to get hectic here.
Member Since: June 27, 2010 Posts: 0 Comments: 760
2108. MiamiHurricanes09
11:06 PM GMT on September 12, 2010
RAW T# up to 6.9.

2010SEP12 224500 6.6 934.2/ +2.0 /129.6 6.6 6.8 6.9 3.2T/18hr OFF OFF 15.44 -71.02 EYE 26 IR 17.66 46.90 COMBO
Member Since: September 2, 2009 Posts: 130 Comments: 21194
2106. Smyrick145
11:06 PM GMT on September 12, 2010
Looks like models are trending a further north motion on 92L. If this thing develops, Texas needs to keep a close eye on this.
Member Since: September 30, 2006 Posts: 0 Comments: 14
2105. Walshy
11:05 PM GMT on September 12, 2010
Quoting StormW:
Good evening!



annular??? yes or no...
Member Since: May 17, 2009 Posts: 2 Comments: 904
2104. RecordSeason
11:05 PM GMT on September 12, 2010
I haven't seen anything like this in the Atlantic since Felix and Dean.

Member Since: June 13, 2010 Posts: 0 Comments: 2336
2103. SouthDadeFish
11:05 PM GMT on September 12, 2010
If Igor isn't a category five hurricane, he's about as close as you can get without being one. Absolutely beautiful. Remarkable rate of intensification we've seen with even warmer waters to come.
Member Since: August 12, 2007 Posts: 11 Comments: 2448
2102. aislinnpaps
11:05 PM GMT on September 12, 2010
Evening, Storm.
Member Since: August 22, 2009 Posts: 0 Comments: 3166
2101. kimoskee
11:05 PM GMT on September 12, 2010
I think 92L is going to bed. True or False?
Member Since: August 17, 2008 Posts: 0 Comments: 672
2100. Max1023
Quoting StormW:
Good evening!


What do you think of Igor? He is somehow STILL Intensifying!
Member Since: July 22, 2008 Posts: 1 Comments: 286
Quoting StormW:
Good evening!


What ya say Chief!
Member Since: August 11, 2010 Posts: 0 Comments: 895
Quoting kmanislander:


Run this visible loop at close to max speed and you will see that the clouds near 16.5 N are moving from E to W near 73. The "center" is just S of that cloud motion.
Any possibility this is already a TD ?
Member Since: Posts: Comments:
Quoting stormwatcherCI:
Thank you.
...,the last few frames of the vis loop it appears that elongated circulation is at the surface,hard to tell 100% but ship reports and sat loops appear to confirm this as elongated surface reflection
Member Since: Posts: Comments:
I bet Igor is a Cat 5 by 11 probably is now!
Member Since: Posts: Comments:

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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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