Potentially dangerous 92L steadily developing; Igor nears hurricane strength

By: Dr. Jeff Masters , 3:04 PM GMT on September 11, 2010

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A tropical disturbance (92L) over the Eastern Caribbean, a few hundred miles south of Puerto Rico, is steadily organizing and appears likely to develop into a tropical depression by tonight or Sunday morning. Satellite loops show an impressive and expanding region of heavy thunderstorms, with good spiral banding and respectable upper-level outflow on all sides. Long range radar out of Puerto Rico shows that heavy rains are now affecting that island, but there is no rotation to the radar echoes evident. However, the rain bands are becoming more intense and more organized. San Juan, Puerto Rico reported a heavy rain squall at 8:44 am this morning, and radar estimates suggest two inches of rain fell in this squall just southeast of San Juan. Wind shear over 92L is low, 5 - 10 knots. The waters beneath are at near-record warmth, 30°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-northwest at 11 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 Mexico's Yucatan Peninsula on Wednesday. The HWRF model has a more northwesterly track, taking 92L over the Dominican Republic, Haiti, and Cuba, but this model has been trending too far north in its tracks. I expect 92L will follow a path south of the islands, bringing it near or just south of Jamaica on Monday, then into the Yucatan Peninsula on Wednesday. On this track, the southern Dominican Republic can expect heavy rains of 3 - 6 inches tonight through Monday morning; southern Haiti can expect similar rains Sunday through Monday, and Jamaica and the Cayman Islands can expect heavier rains of 4 - 8 inches Monday and Tuesday. Eastern Cuba will probably escape 92L's heaviest rains in this scenario (Figure 2.)

Intensity forecast for 92L
I can't find any reason to doubt this will be a tropical storm by Sunday or Monday, and potentially a Category 1 or 2 hurricane by Wednesday, if 92L avoids passage over Hispaniola and Cuba. The SHIPS model predicts wind shear will remain low, 5 - 10 knots, through the period, and makes 92L a Category 1 hurricane by Monday night. 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. The first Air Force Hurricane Hunter mission into 92L is scheduled for Sunday afternoon, but there will be a research mission by the National Center for Atmospheric Research G-V jet today that will give us valuable information on 92L's large scale environment and potential for development.


Figure 2. Forecast rain amounts from 92L from the 2am EDT Saturday run of the GFDL model. This model predicts most of 92L's heaviest rains will miss Haiti, but will affect Jamaica, the Cayman Islands, and the Yucatan Peninsula. Image credit: Morris Bender, NOAA/GFDL.

Igor
Tropical Storm Igor is very close to hurricane strength, and appears destined to become a large and powerful major hurricane over the Central Atlantic in the days to come. Wind shear is moderate, 15 - 20 knots, waters are warm, 28°C, and Igor has moistened its environment enough to keep the dry air of the Saharan Air Layer (SAL) at bay. Igor will track west under the influence of a strong ridge of high pressure for the next three days, then turn more to the west-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 has a slight chance of making landfall on the U.S. East Coast or Canada. Climatology shows that about 10% 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 5% for Canada. The forecast steering pattern for the coming two weeks from the GFS model 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. The odds of Igor hitting land in the U.S. or Canada are probably close to their climatological 10% and 5% probabilities, respectively.

Elsewhere in the tropics
A new tropical wave (Invest 93L) emerged from the coast of Africa yesterday, and is already showing signs of organization. Most of the models predict 93L will develop into a tropical depression 2 - 4 days from now, and NHC is giving 93L a 30% chance of developing by Monday.

Next post
This may be my only post today; I'll have a new post Sunday morning.

Jeff Masters

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Member Since: Posts: Comments:
Quoting CybrTeddy:
6.0 would be about 115 knots, or Category 4.


I believe we have a rapid deepening system on our hands. The advisory stated that Igor had pressures of 988 mb. Now T-NUMBERS are showing 966 mb? A drop of 22 mb in a few hours? O.o
Member Since: April 1, 2010 Posts: 9 Comments: 2699
CI# /Pressure/ Vmax
5.5 / 962.0mb/102.0kt


Major Hurricane anyone???
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Quoting 1965:

No worries in the BOC. It'll be inland before morning.


good, cause that would really mess up the fishing :)
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Quoting WeatherNerdPR:

Igor's a MONSTER!


I think it has an excellent shot at Cat 5... like Ivan...

-Snow
Member Since: April 1, 2010 Posts: 9 Comments: 2699
2316. emcf30
Post 2296. Is the blob located in the BOC the energy left over from ex-Gaston and is there any potential of future development?
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6.0 would be about 115 knots, or Category 4.
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2314. 1965
Quoting jodi4lsu:
Good morning everyone!!! Did I miss the general opinion on the flare up in the BOC? It looks a little concerning, but I don't exactly have all the steering patterns down yet....

No worries in the BOC. It'll be inland before morning.
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Quoting Snowlover123:


Igor's winds, according to DVORAK T NUMBERS are somewhere between 90 kts. and 115 kts.

-Snow

Igor's a MONSTER!
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Quoting WeatherNerdPR:

Oh My God.


Igor's winds, according to DVORAK T NUMBERS are somewhere between 90 kts. and 115 kts.

-Snow
Member Since: April 1, 2010 Posts: 9 Comments: 2699
Good morning everyone!!! Did I miss the general opinion on the flare up in the BOC? It looks a little concerning, but I don't exactly have all the steering patterns down yet....
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hey guys 92L looks better than last night and heading for jamaica and us here in cayman
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2306. surfmom
Very thankful 92L didn't crank up.....I'm locking the door between the Yuc & Cuba, got the sign up as well, No Solicitors....maybe that funny dude dressed in the grim reaper outfit could hang out as well
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Quoting CybrTeddy:
CI# /Pressure/ Vmax
5.3 / 966.0mb/ 97.2kt


Oh My God.
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Raw T# for Igor have shot up to almost 6.0
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Quoting breald:


I know I really hope he does not hit land as a cat 4. I know Bermuda has sturdy buildings but that would be devastating.

But it wouldn't be the first time a storm threatened the island this year. Colin, Danielle and Fiona all put TS Watches/Warnings on the island.
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I think they have the wrong date on the release cause this came out this morning.

Met Service Of Jamaica

NEWS RELEASE
Saturday, September 12, 2010 – 5:00 a.m.

**** BROAD AREA OF LOW PRESSURE MOVING TOWARDS CENTRAL CARIBBEAN ***


A broad area of Low Pressure is now located over the east-central Caribbean Sea and is moving toward the west.

Satellite imagery indicates that the cloudiness and thunderstorms associated with the Low Pressure system remain disorganized. Conditions are, however, favourable for gradual development and a tropical cyclone could still form during the next day or two as the system moves toward the western Caribbean Sea.

As the system progress closer to Jamaica, heavy showers and flash flooding are possible.

Due to the current potential for the system to strengthen while moving westward, marine interests are advised that weather conditions will gradually deteriorate today and tomorrow. Thundershowers and strong, gusty winds are forecast over southern waters and small craft operators, especially fishers on the cays and banks, should exercise extreme caution. Those in port are urged not to venture far from the mainland.

The Meteorological Service will continue to monitor the progress of this system and all interests should pay special attention to subsequent Releases.
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CI# /Pressure/ Vmax
5.3 / 966.0mb/ 97.2kt

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2300. surfmom
Quoting Snowlover123:


After taking a fall off a cliff, it appears that Gaston hadn't died after all! He strode toward the Beast's castle with fury and demonic rage.... :P

Big Laugh out LOUD
Kinda like the Cat came back tune...cept we could sing "the Cane came back, they thought it was a gonner, but the Cane came back"......................
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Quoting surfmom:
Good Morning Kman - Wow - seeing your perked me up faster then my coffee this morning...always good to see a FAV Island man and read your views on the day


Hi there

I am about to get my coffee, I just heard the last gasp from the coffee maker LOL.

Not too much that is pressing tropically speaking this morning. 92L continuing to struggle with the less favourable Eastern and Central Caribbean and Igor seemingly on track for a recurve. Igor is about to intersect the 18 N lat line which is good news for the Leewards and a sign that the track is changing, albeit slowly at first.

As far as the future of 92L goes it has good upper level support and an excessive amount of ocean heat content to work with. It could still become a problem by early tomorrow if it starts to tap into the more generally conducive area in the Western Caribbean. For now we can be thankful it did not get going just outside the Caribbean.
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2298. breald
Where are you guys seeing ex-gaston? The only new invest is way east of Bermuda at a 10% chance for development.
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2297. KBH
Does any one know if noaa has a flood monitoring system in place for the caribbean area? and if it does not, should this be something worth considering in the case of those weather systems that never make it to storm status, but produce significant amounts of rainfall in short periods resulting in flooding e.g 92L and TD13
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Hi all, in the absence of data confirming the navy, invest 93 L, and tropical depression is 12 L, as it has a 100% chance of development on the other hand, invest 92 L, now it has a 50% chance of development.

A greeting from Spain.
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Met Service of Jamaica website

September 12, 2010 at 5:00 a.m.

LOCAL WEATHER FORECAST

SIGNIFICANT FEATURE…Trough across the central Caribbean, including Jamaica.

Comment
Comment… The Trough is expected to linger across the central and western Caribbean for the next three to four days

Maximum temperatures expected today:
Kingston… 33 degrees Celsius.
Montego Bay… 33 degrees Celsius.

24-HOURS FORECAST
This Morning… Partly cloudy across sections of northern parishes.

This Afternoon… Expect scattered showers and thunderstorms across sections of most parishes.

Tonight… Partly cloudy becoming fair.


3-DAYS FORECAST (starting tomorrow)
Tue… Periods of showers and thunderstorms across the island.

Wed/Thurs… Scattered afternoon showers and thunderstorms across central and western parishes

Regionally…
An area of Low Pressure across the southeastern Caribbean has a sixty percent chance for developing into a tropical cyclone and is expected to move into the central Caribbean, late tonight and be in the vicinity of Jamaica by late Monday night into Tuesday.


rlb
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Quoting surfmom:
coming back from the dead...??? hopefully not to haunt


After taking a fall off a cliff, it appears that Gaston hadn't died after all! He strode toward the Beast's castle with fury and demonic rage.... :P
Member Since: April 1, 2010 Posts: 9 Comments: 2699
Quoting StormW:


Slightly better than yesterday.
Morning Storm Normally you do not make an update on your blog on weekends are you going to do a special edition like yesterday
Member Since: July 14, 2009 Posts: 0 Comments: 3022
2291. breald
Quoting WeatherNerdPR:

Couple the tracks with forecast intensity, and Igor could be retired.


I know I really hope he does not hit land as a cat 4. I know Bermuda has sturdy buildings but that would be devastating.
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2290. surfmom
Good Morning Kman - Wow - seeing your avatar perked me up faster then my coffee this morning...always good to see a FAV Island man and read your views on the day
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Quoting surfmom:
Ick, tornadolarkin
jeepers is this a sneaky creeper????? any opinions why this won't BE a possible concern?

Could it be...Ex-Gaston?
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Good morning all

92L looks to be just about on the 15 degree N lat line on a heading I would estimate to be 275/280 or due West. Still no real organization present and the 850 vort is not impressive at all. My expectations for this have always been for little to happen until after 75 W which it should get to soon.

The longer it takes to organize the better it will be for those downstream the system.
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Quoting StormW:


Slightly better than yesterday.


Storm, you think the chances have increased today for a possible strike on the islands, despite the shift eastward (to right) by the NHC and model tracks?
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2286. surfmom
Quoting Snowlover123:


Good Morning! To answer your question (and I'm hypothetically speculating,) that may be the remnants of Gaston....
coming back from the dead...??? hopefully not to haunt
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Quoting breald:
Morning All!! I sure hope Igor takes a track like Earl did for Bermuda's sake. The current tracks doesn't look good for them.

Couple the tracks with forecast intensity, and Igor could be retired.
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2284. surfmom
Ick, tornadolarkin
jeepers is this a sneaky creeper????? any opinions why this won't BE a possible concern?
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2283. IKE
If 92L is moving from 240-360 miles a day(10-15mph), it should reach the Yucatan in about 3 days.

Quoting Cotillion:


I think 93L is going to get the jump on 92L and become Julia.

Yeah, hopefully 92L just does another Gaston - i.e. nothing. However, way too early to tell yet.


I meant to say 93L becomes Julia, not Karl.
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Quoting tornadolarkin:
Is this something to be concerned about?


Good Morning! To answer your question (and I'm hypothetically speculating,) that may be the remnants of Gaston....
Member Since: April 1, 2010 Posts: 9 Comments: 2699
2280. breald
Morning All!! I sure hope Igor takes a track like Earl did for Bermuda's sake. The current tracks doesn't look good for them.
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Chances of Igor brushing the northern islands??
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Quoting IKE:


Just like the models have been forecasting....92L struggles to get designated and 93L becomes the next TD and probably Karl.

Models show nothing threatening the northern gulf coast for at least the next 7 days...and maybe longer, which is great news.


I think 93L is going to get the jump on 92L and become Julia.

Yeah, hopefully 92L just does another Gaston - i.e. nothing. However, way too early to tell yet.
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Quoting tornadolarkin:
Wow, looks like he has a nice eye and eyewall.

Wow. Impressive.
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2276. IKE
Quoting Cotillion:
TD12 at 11 then.

And 92L goes backwards.. out comes the orange crayon.


Just like the models have been forecasting....92L struggles to get designated and 93L becomes the next TD and probably Karl.

Models show nothing threatening the northern gulf coast for at least the next 7 days...and maybe longer, which is great news.
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Quoting tornadolarkin:
Wow, looks like he has a nice eye and eyewall.


Seems to be in a phase of Rapid Intensification.......I see a cat 3 by end of day...
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TD12 at 11 then.

And 92L goes backwards.. out comes the orange crayon.
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2273. 1965
Quoting StormW:


Best I can make is, 15.0N;70.4W


I'd that is spot on. NOAA buoy at 15n/67.5w clearly shows the passage of the weak COC overnight.


°
09 12 6:50 am S 9.7 13.6 3.9 6 4.5 - 29.77 +0.01 83.5 86.4 76.1 - - -
09 12 5:50 am SSE 13.6 15.5 3.6 7 4.5 - 29.75 -0.02 84.2 86.4 76.6 - - -
09 12 4:50 am SE 11.7 13.6 3.3 6 4.7 - 29.75 -0.05 84.2 86.4 75.7 - - -
09 12 3:50 am SSE 9.7 13.6 3.3 6 4.9 - 29.76 -0.06 84.0 86.4 76.3 - - -
09 12 2:50 am SE 7.8 9.7 3.3 7 4.8 - 29.78 -0.05 83.8 86.5 76.1 - - -
09 12 1:50 am ESE 7.8 9.7 3.3 7 4.8 - 29.80 -0.01 84.0 86.5 75.4 - - -
09 12 12:50 am E 5.8 7.8 3.0 7 4.5 - 29.82 +0.03 84.0 86.5 75.4 - - -
09 11 11:50 pm E 9.7 11.7 3.6 7 4.6 - 29.83 +0.04 84.4 86.5 75.4 - - -
09 11 10:50 pm E 9.7 11.7 3.3 7 4.7 - 29.81 +0.02 84.4 86.5 75.4 - - -
09 11 9:50 pm ENE 11.7 13.6 3.3 7 4.3 - 29.79 +0.02 84.0 86.5 76.3 - - -
09 11 8:50 pm E 9.7 11.7 3.9 6 4.4 - 29.79 +0.01 84.0 86.5 75.6 - - -
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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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