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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2023. JLPR2
Quoting AtHomeInTX:


LOL. But you make me laugh! So I guess I'll give you that one. :)


Well, walking to your doom laughing makes it a little worse. XD
Member Since: September 4, 2007 Posts: 7 Comments: 8459
Where are we going?
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Quoting NCHurricane2009:


What, toward the CONUS? Where on the CONUS? Is NC in the picture?


OH yes.....been saying that for sometime now.
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Quoting CoopNTexas:
Further North into Mexico on that run. Ridge weaker in Texas.


Oh boy. Here we go.
Member Since: August 24, 2010 Posts: 0 Comments: 459
I think it will develop...maybe wednesday or so. Don't think it's going to be a bomb tho.
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Quoting traumaboyy:


Ladies first maam....I not make the rules!!


LOL. But you make me laugh! So I guess I'll give you that one. :)
Member Since: August 24, 2010 Posts: 0 Comments: 459
Quoting reedzone:
The EURO has Igor directing towards the CONUS, strong ridge over head, this is a very possible scenario. Again, this "fish" storm you speak of DOES NOT EXIST... yet, or may never be one. Still have days to watch it.


What, toward the CONUS? Where on the CONUS? Is NC in the picture?
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Quoting KerryInNOLA:
Bottom line. Don't ever trust the models further out that about a week. They don't develop invests that exist and at the same time develop systems that don't exist at all. And they can't be sued , for you litigious types.
A Week!!! I trust them to about 72 hrs. Sometimes that's even a stretch!
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The EURO has Igor directing towards the CONUS, strong ridge over head, this is a very possible scenario. Again, this "fish" storm you speak of DOES NOT EXIST... yet, or may never be one. Still have days to watch it.
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That trough won't turn IGOR......NO WAY
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Quoting KerryInNOLA:
Bottom line. Don't ever trust the models further out that about a week. They don't develop invests that exist and at the same time develop systems that don't exist at all. And they can't be sued , for you litigious types.


Yeah I've noticed that especially this year. Them not seeing existing storms and making up non-existing ones. So I'm not good at it but it looks like more wait and see. :)
Member Since: August 24, 2010 Posts: 0 Comments: 459
Further North into Mexico on that run. Ridge weaker in Texas.
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AL, 93, 2010091206, , BEST, 0, 131N, 195W, 30, 1006, DB

could see a renumber soon

atcf now has winds of 35mph
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OMG.. the EURO.. ummm.... wow
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Quoting AtHomeInTX:


Lol. Why do we have to doom first??


Ladies first maam....I not make the rules!!
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Quoting CoopNTexas:
Once again, EURO sends weak storm in Mexico.



Well at least they think it exists. Lol.
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Quoting Hurricanes101:
wow ECMWF is a full 10 degrees further west on this run


What, the ECMWF on Igor?
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Quoting traumaboyy:


Women and children first!!!!


Lol. Why do we have to doom first??
Member Since: August 24, 2010 Posts: 0 Comments: 459
Quoting xcool:
we all doom
Where is the jet stream on this mess?
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Once again, EURO sends weak storm in Mexico.

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wow ECMWF is a full 10 degrees further west on this run
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2000. xcool
lol
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1999. JLPR2
Quoting traumaboyy:


Women and children first!!!!


LOL!
Member Since: September 4, 2007 Posts: 7 Comments: 8459
Quoting xcool:
we all doom


Women and children first!!!!
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Quoting F4PHANTOM:
STILL sending 92L across the Yucatan!!!


A tad farther north and east than last nights run anyway.
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1996. xcool
we all doom
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Yeah, definetly no spin at 55W 10N, yawn...
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Quoting TampaSpin:


Looks like things just changed completly with the EURO models....OMG.....Igor can't go through that High like that........NO WAY!


well the next frame turns it north anyway
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Quoting CoopNTexas:
and there he goes, busting the through the high...
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flip flop on the ridge again with 92L from 12z run.
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1991. JLPR2
Quoting sunlinepr:
Link

No spin at 55W 10N????
Well, it's time for bed...... Hasta la Vista....


Buenas Noches :D
Member Since: September 4, 2007 Posts: 7 Comments: 8459
Road closed 9/17/2010!
Quoting xcool:
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Quoting xcool:


Looks like things just changed completly with the EURO models....OMG.....Igor can't go through that High like that........NO WAY!
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Link

No spin at 55W 10N????
Well, it's time for bed...... Hasta la Vista....
Member Since: August 2, 2010 Posts: 21 Comments: 9656
1985. xcool
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Might be a ULL forming, but no llc.
Quoting sunlinepr:
Does anyone notice a spin at 55W 10N????
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Quoting sunlinepr:
Does anyone notice a spin at 55W 10N????


It looks like Igor is pulling the clouds up from there and just seems to be spinning.
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1981. JLPR2
Quoting sunlinepr:
Does anyone notice a spin at 55W 10N????


I dont see anything.
Member Since: September 4, 2007 Posts: 7 Comments: 8459
Does anyone notice a spin at 55W 10N????
Member Since: August 2, 2010 Posts: 21 Comments: 9656


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That gap may not be big enough. Next please!
Quoting CoopNTexas:
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Quoting TampaSpin:


Models are starting to show that Northward turn as i have been saying....need to watch this close!!!!


Yeah. Sigh. Wonder why the globals are dropping it?
Member Since: August 24, 2010 Posts: 0 Comments: 459



Maybe I'm ready for bed, but does anyone notice a spin at 55W 10N????
Member Since: August 2, 2010 Posts: 21 Comments: 9656
Quoting TampaSpin:


Models are starting to show that Northward turn as i have been saying....need to watch this close!!!!


Thanks.....scary now!!
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We now have Hurricane Igor again.
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ROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 AM EDT SUN SEP 12 2010

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

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON HURRICANE
IGOR...LOCATED ABOUT 1275 MILES EAST OF THE LEEWARD ISLANDS.

SHOWERS AND THUNDERSTORMS ARE LIMITED IN ASSOCIATION WITH A
BROAD AREA OF LOW PRESSURE LOCATED OVER THE EAST-CENTRAL CARIBBEAN
SEA. HOWEVER...ENVIRONMENTAL CONDITIONS APPEAR FAVORABLE FOR
DEVELOPMENT OF THIS SYSTEM...AND A TROPICAL DEPRESSION COULD STILL
FORM DURING THE NEXT COUPLE OF DAYS AS IT MOVES WESTWARD NEAR 15
MPH. THERE IS A HIGH CHANCE...60 PERCENT...OF THIS SYSTEM BECOMING
A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. REGARDLESS OF
DEVELOPMENT...LOCALLY HEAVY RAINFALL IS POSSIBLE IN THE VIRGIN
ISLANDS...PUERTO RICO...AND HISPANIOLA DURING THE NEXT DAY OR SO.
THESE RAINS COULD CAUSE LIFE-THREATENING FLASH FLOODS AND MUD
SLIDES...ESPECIALLY IN MOUNTAINOUS TERRAIN.

SHOWERS AND THUNDERSTORMS CONTINUE TO ORGANIZE IN ASSOCIATION WITH
AN AREA OF LOW PRESSURE LOCATED ABOUT 300 MILES EAST-SOUTHEAST OF
THE CAPE VERDE ISLANDS. IF CURRENT TRENDS CONTINUE...ADVISORIES
COULD BE INITIATED AT ANY TIME TODAY. INTERESTS IN THE CAPE VERDE
ISLANDS SHOULD CLOSELY MONITOR THE PROGRESS OF THIS SYSTEM IN CASE
WATCHES OR WATCHES ARE REQUIRED. THERE IS A HIGH CHANCE...90
PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS AS IT MOVES GENERALLY WESTWARD AT 10 TO 15 MPH.

A WEAK AREA OF LOW PRESSURE LOCATED ABOUT 900 MILES EAST OF BERMUDA
IS PRODUCING DISORGANIZED SHOWER ACTIVITY. DEVELOPMENT OF THIS
SYSTEM APPEARS UNLIKELY BEFORE IT IS ABSORBED BY A FRONTAL SYSTEM
IN THE NEXT DAY OR SO. THERE IS A LOW CHANCE...10 PERCENT...OF
THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS
IT MOVES NORTHWARD NEAR 20 MPH.



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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.