Category 3 Hurricane Irene tracks northwest through the Bahamas

By: Dr. Jeff Masters , 8:55 PM GMT on August 24, 2011

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Hurricane Irene remains a powerful category 3 this afternoon, with maximum sustained winds of 120 mph. Irene is moving northwest through the Bahamas at 12 mph, and its center has cleared the northern edge of Crooked Island. The next islands in the path of Irene are Rum Cay (population 80) and Cat Island (population 1700), which it will encounter later tonight. Irene will track northeast of Long Island (in the Bahamas) over the next 24 hours. George Town has been reporting wind gusts up to around 40 mph this afternoon, and wind speed will likely increase during the next 12 hours as Irene's center passes about 30-40 miles to their northeast. Long Island in the Bahamas will likely see category 1 winds, which begin at 74 mph. Shelters on New Providence and Grand Bahama are open and ready for business, and Grand Bahama International Airport will remain closed until Irene passes.

Irene continues to look well-organized on satellite, especially compared to yesterday afternoon. Since then, intense upward motion, and therefore strong thunderstorm activity, has encompassed the center on all sides, which has led to a well-defined eye. Throughout the morning, Irene's eye wall has shrunk, and a new eye wall could be developing, although it remains unclear at this point. If this is the case, it could lead to some temporary weakening of the hurricane, which would be good for the Bahamas. This afternoon, Irene's hurricane-force winds extend 50 miles from the center, and tropical storm-force winds extend up to 205 miles from the center. Earlier this morning, an Air Force Hurricane Hunter mission investigated Irene and a NOAA Gulfstream (Gonzo) is currently collecting data around the hurricane.


Figure 1. Microwave satellite imagery of Irene captured at 8am this morning. Image source: Naval Research Laboratory.

Track forecast for Irene
NOAA has continued dropsonde missions today, scouring the atmosphere for data as far north as the waters off of South Carolina. Every bit of upper-air data that the models can ingest will lead to better forecasts and decreased uncertainty. These missions are an investment that pay off. Irene will track through the central Bahamas today, the northwestern Bahamas on Thursday, and approach the Outer Banks of North Carolina on Friday. Beyond this there is a bit of divergence in the models. Both the GFDL and the HWRF are forecasting a landfall on Long Island, New York, and the ECMWF continues to suggest a landfall even further west than that. NOGAPS is still the eastern outlier, which misses the U.S. all together and makes landfall in Canada. Today the official track forecast from the National Hurricane Center agrees with the GFS forecast through Saturday morning, and then diverges ever so slightly to the west of that through Monday. It has become clear over the past 3 days that everyone on the East Coast from North Carolina to Maine should be prepared to feel impacts from Hurricane Irene.


Figure 2. Official track forecast provided by the National Hurricane Center.

Intensity forecast for Irene
Irene continues to be embedded in a large envelope of moisture, and wind shear is expected to remain low to moderate, 5 - 20 knots, for the next three days. With water temperatures very warm, 28 - 30°C, these conditions should allow for intensification to a category 4 hurricane (winds of 131 to 155 mph). The only reliable model that's not forecasting this intensification is the GFS, and this is likely due to its relatively course spatial resolution. The National Hurricane Center expects Irene to intensify to a category 4 tomorrow, with a decrease in intensity back to a category 3 on Friday.

Links
For those of you wanting to know your odds of receiving hurricane force or tropical storm force winds, check out the NHC wind probability product.

Wunderground has detailed storm surge maps for the U.S. coast.

Our Wundermap is also a great resource for tracking hurricanes, with the ability to turn on multiple layers of data, including satellite, official track forecast, and current weather observations from not only the U.S. but the Caribbean and Bahamas, as well. Here's a link to get you started.

Angela

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2918. Grothar
Either dry air pocket or another EWRC.

Member Since: July 17, 2009 Posts: 69 Comments: 25366
Quoting DFWjc:


Right, but all i seen for futurecast is straight north and then northeast for the last 4 days, yet it's only gone two directions, NW and WNW...where is this N direction coming from?


Haven't seen anyone claim it going N yet. If it's going N on my maps I need to turn my computer around.
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Quoting TigerFanOrl:


What an awful thing to say! Just keep your eye on this storm because mother nature does what mother nature wants to do. These same weathermen SHEN is relying on so much tells you it will rain when it doesn't. You are not ignorant just concerned as we all are and I've scene many hurricanes, storms do opposite of what "Experts" say. These same weathermen and computers have been wrong most of the time on this storm so far.
This storm is not "going to Florida". Folks in South Carolina and Points North have cause to keep an eye out.
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Irene might be pumping its own ridge slightly to its NW......
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Quoting TampaSpin:



After looking at it,,,,although it does not say marine......its for sure off shore.....SORRY
No worries..but I'm not exxagerating. I yelled out loud "What the hell"? and frantically went to the zones. It was pretty funny.
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2913. Grothar
Quoting charlottefl:




Thanks for posting it for me. BTW I responded to your earlier question. did you see it?
Member Since: July 17, 2009 Posts: 69 Comments: 25366
2912. 7544
new covection building to the west
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2911. Remek
Quoting iahishome:


Bullet Proof glass and solid granite walls. It's probably the most hurricane proof building in the city. I don't know anything about the storm surge potential though.


If it's gas and radiation proof it better darn well be waterproof, too!
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2910. nigel20
Quoting Remek:


Check the tracking dots vs the eye on the longer NOAA satellite loops. They've been pretty spot on so far.

Yea, they've really done well with Irene over the last couple of days.
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2909. scott39
Quoting scott39:
Thanks, When does Irene have to go NNW to hit the current forecast point?
(next point)
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Those that follow.......if you go to the site......i have 5 interactive Loops on it........channel 2 shows the eye very well yet.
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POOF
Quoting TigerFanOrl:


What an awful thing to say! Just keep your eye on this storm because mother nature does what mother nature wants to do. These same weathermen SHEN is relying on so much tells you it will rain when it doesn't. You are not ignorant just concerned as we all are and I've scene many hurricanes, storms do opposite of what "Experts" say. These same weathermen and computers have been wrong most of the time on this storm so far.
POOF
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Quoting pctatc:
First time poster, long time lurker. Just had a pretty significant after shock here in Warrenton, VA. lasted about 25 secs. The house was vibrating pretty good. And to think I stayed up late tonight to catch the developments on Irene which appears to be heading more my way than earlier this evening. Heck of a week here in the mid Atlantic.



We felt it here in Madison as well... just when I was finally beginning to fall asleep, dangit!

Maybe I'll have a nightcap...
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For those of you who use Free online storage... 21Gb free online storage

Free service will soon be in operation...

Link

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2904. DFWjc
Quoting Remek:


Check the tracking dots vs the eye on the longer NOAA satellite loops. They've been pretty spot on so far.


Right, but all i seen for futurecast is straight north and then northeast for the last 4 days, yet it's only gone two directions, NW and WNW...where is this N direction coming from?
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Microwave pass shows well what'a going on with the eye:

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Quoting drg0dOwnCountry:

Hurricanes and intensity, when the topic is brought up i will offer my knowledge. And this will be further discussed later when people start asking why.

So far for current tracking, since yesterday i was pointing out the fact that Irene went through a Hebert Box and might be considered an annular hurricane, which makes it harder to forecast.



The Hebert boxes are an interesting anomaly; even Hebert said they weren't really a good tool for determining storms that would make a CONUS landfall; more of a de facto gauge...

Irene's recent ERWC and lack of pressure rise while it was going on might be indicator of an annular storm but the question is, does she meet the other requirements? She's not as symentrial as I would think she would need to be; she has, in addition, been effected by dry air and shear more than I would expect if she were annular. On the other hand, she could go annular; annular hurricanes are not born annular, they develop the chrateristics of annular storms and typically aren't annular for very long, and I have now used that word far more than I have ever used it before...
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2901. scott39
Quoting Grothar:


I would provide it if I knew what you wanted. Was it something I posted earlier?
post 2889
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2900. Remek
Quoting DFWjc:
I don't understand how a storm is moving 11 mph NW, but is computer tracking N for the last 2 days? Am i just crazy??


Check the tracking dots vs the eye on the longer NOAA satellite loops. They've been pretty spot on so far.
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Quoting tpawxguy:
You absolutely just scared the hell out of me. I thought I missed something I'm paid not to miss!



After looking at it,,,,although it does not say marine......its for sure off shore.....SORRY
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2898. Remek
Quoting DFWjc:
I don't understand how a storm is moving 11 mph NW, but is computer tracking N for the last 2 days? Am i just crazy??


Check the tracking dots vs the eye on the longer NOAA satellite loops. They've been pretty spot on so far.
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2897. scott39
Quoting charlottefl:


Thanks, When does Irene have to go NNW to hit the current forecast point?
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2896. Grothar
Quoting scott39:
Hey Grothar do you have a link for a thingabathomer chart that shows the degrees for directions of a TC? TIA


I would provide it if I knew what you wanted. Was it something I posted earlier?
Member Since: July 17, 2009 Posts: 69 Comments: 25366
Quoting ShenValleyFlyFish:
Not crazy just uninformed (ignorant). Hurricanes follow scientific principles which are incorporated into models and studied by "weathermen" (meteorologists), they do not "have minds of their own".


What an awful thing to say! Just keep your eye on this storm because mother nature does what mother nature wants to do. These same weathermen SHEN is relying on so much tells you it will rain when it doesn't. You are not ignorant just concerned as we all are and I've scene many hurricanes, storms do opposite of what "Experts" say. These same weathermen and computers have been wrong most of the time on this storm so far.
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Quoting Remek:


Irene has a posse.


(not to discount your going thru EQ/aftershocks, just a humorous twitter post from the other day)


Felt the shock here in MD as well.
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Quoting Remek:


The most important parts above and below ground can.



Bullet Proof glass and solid granite walls. It's probably the most hurricane proof building in the city. I don't know anything about the storm surge potential though.
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Quoting TampaSpin:


OK, OK,.....my bad......i just seen it and posted......LOL
You absolutely just scared the hell out of me. I thought I missed something I'm paid not to miss!
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Quoting silverstripes:


Appears the EWRC may be over then. The 8 mile wide eye in the previous vortex message has been replaced by the larger eye.


Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 25th day of the month at 03:19Z
M. Eye Shape & Diameter: Circular with a diameter of 8 nautical miles


Not quite, means that the outer eyewall has now choked off the inner eyewall and become the dominant feature, but hasn't closed off yet as reported by RECON. But she's getting there. And she's actually dropped 6 mb since the start of the cycle. Very very rare but larger storms do have the potential to resist rises in pressure during eyewall cycles.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
2890. Dunkman
I'm really interested to see what they do about the intensity. The winds have not justified a cat. 3 for a long time now, but the pressure keeps dropping. I think they do not want to weaken it knowing that the winds are certain to ramp up at this pressure once the EWRC is over. That said, I'm expecting them to drop the winds at 2am after recon could not even find 100kt. flight level on this last pass.
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Quoting scott39:
Hey Grothar do you have a link for a thingabathomer chart that shows the degrees for directions of a TC? TIA


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2888. DFWjc
I don't understand how a storm is moving 11 mph NW, but is computer tracking N for the last 2 days? Am i just crazy??
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Quoting Grothar:


It's OK, T. I forgot to put out the garbage the other night. No need to tell you what flak is. You want to switch places? :)




Dang, glad you reminded me..........its garbage pick up tomorrow morning for us. BB in a minute.
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2886. nigel20

Look at Irene's outflow.
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2885. scott39
Hey Grothar do you have a link for a thingabathomer chart that shows the degrees for directions of a TC? TIA
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2884. Grothar
PI, you still up?
Member Since: July 17, 2009 Posts: 69 Comments: 25366
2883. 7544
look at the new blowup to the west so close to andros islands
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2882. Remek
Quoting Cat5Hurricane250:
2 mb lower
H. Minimum Sea Level Pressure: 950mb (28.05 inHg)

No mention of the small inner eyewall.
L. Eye Character: Open from the west to the northeast
M. Eye Shape & Diameter: Circular with a diameter of 32 nautical miles (37 statute miles)


Irene's gonna get nasty once the EWRC is over with.
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Quoting Cat5Hurricane250:
2 mb lower
H. Minimum Sea Level Pressure: 950mb (28.05 inHg)

No mention of the small inner eyewall.
L. Eye Character: Open from the west to the northeast
M. Eye Shape & Diameter: Circular with a diameter of 32 nautical miles (37 statute miles)


Appears the EWRC may be over then. The 8 mile wide eye in the previous vortex message has been replaced by the larger eye.


Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 25th day of the month at 03:19Z
M. Eye Shape & Diameter: Circular with a diameter of 8 nautical miles
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.
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Quoting jfm1975:
OK..call me crazy..but I keep seeing Irene continuing on an essentially a bee line for florida. I know every modek and weatherman has it hitting the NYC area...but this monster is getting way to close for comfort. And hurricanes are notorious for having a mind of their own..I really hope I am wrong
Not crazy just uninformed (ignorant). Hurricanes follow scientific principles which are incorporated into models and studied by "weathermen" (meteorologists), they do not "have minds of their own".
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2878. Remek
Quoting pctatc:
First time poster, long time lurker. Just had a pretty significant after shock here in Warrenton, VA. lasted about 25 secs. The house was vibrating pretty good. And to think I stayed up late tonight to catch the developments on Irene which appears to be heading more my way than earlier this evening. Heck of a week here in the mid Atlantic.



Irene has a posse.


(not to discount your going thru EQ/aftershocks, just a humorous twitter post from the other day)
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2877. zuglie
I think its going to track more westward than they thought !
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Quoting Orcasystems:





I'm going to bed... course 312 steady as an arrow


Same way I see it. It better starting being lifted due north soon or NE to stay on track.
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2875. Grothar
Quoting TampaSpin:


OK, OK,.....my bad......i just seen it and posted......LOL


It's OK, T. I forgot to put out the garbage the other night. No need to tell you what flak is. You want to switch places? :)
Member Since: July 17, 2009 Posts: 69 Comments: 25366





I'm going to bed... course 312 steady as an arrow, Port of track
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this could be a start of a RI when the eye comes out


night
Member Since: May 21, 2006 Posts: 5091 Comments: 114719
Quoting scCane:


Last post of the night for me. Anyone near Cape Hatteras needs to watch this one for any western shift.
After all the days the GFDL was the left most outlier, through 8P Fri. it's now right of the model consensus.
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2 mb lower
H. Minimum Sea Level Pressure: 950mb (28.05 inHg)

No mention of the small inner eyewall.
L. Eye Character: Open from the west to the northeast
M. Eye Shape & Diameter: Circular with a diameter of 32 nautical miles (37 statute miles)
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2870. nigel20
Quoting MiamiHurricanes09:
A lil' lower actually. 947.3mb.

050800 2402N 07550W 6963 02712 9473 +166 +145 334013 014 018 001 03

You are kidding?
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950mb on the dropsonde, but I don't think that hit the lowest pressure. Winds were also 9mph, so roughly 949mb by rule of thumb.

000
UZNT13 KNHC 250519
XXAA 75057 99240 70758 08045 99950 27200 27008 00957 ///// /////
92238 25600 28009 85983 22200 28509 70666 17025 33513 88999 77999
31313 09608 80508
61616 AF302 1709A IRENE OB 22
62626 EYE SPL 2403N07583W 0512 MBL WND 27509 AEV 20802 DLM WND 30
509 950696 WL150 27510 084 REL 2403N07584W 050759 SPG 2403N07583W
051140 =
XXBB 75058 99240 70758 08045 00950 27200 11850 22200 22756 20241
33718 18049 44696 16421
21212 00950 27008 11850 28509 22751 32510 33696 33014
31313 09608 80508
61616 AF302 1709A IRENE OB 22
62626 EYE SPL 2403N07583W 0512 MBL WND 27509 AEV 20802 DLM WND 30
509 950696 WL150 27510 084 REL 2403N07584W 050759 SPG 2403N07583W
051140 =
;
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting Levi32:
Well this is not good....recent AVHRR SST passes indicate that 27C waters extend right up to the coast of Long Island. This is strange because other analysis I have seen (such as LSU) says that SSTs drop below 25C rapidly north of the Gulf Stream there, but upon using a photo-editing program to figure out what temperature on the scale that the colors near Long Island correspond to, this image indicates 27C. I wonder which analysis is correct.







from EMC Marine Modeling and Analysis Branch - not sure if this is the same as LSU. Not showing 27 all the way in, but it's close.

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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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