Hurricane Irene Approaches the Bahamas

By: Dr. Jeff Masters , 7:42 AM GMT on August 24, 2011

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As of 2AM EDT, Hurricane Irene was located at 21.3N, 72.6W, 400 miles southeast of Nassau. It was moving west-northwest at 9 mph with maximum sustained winds of 100 mph, making it a Category 2 storm on the Saffir-Simpson scale. Irene has a minimum central pressure of 966 mb. Hurricane warnings have been issued for all of the Bahamas and the Turks and Caicos Islands. Tropical storm warnings are in effect for Haiti from Le Mole St. Nicholas to the Dominican Republic border.

Satellite Views
Figure 1 shows that Irene has a large eye visible in infrared imagery, (26 miles across accoring to a report from the Hurricane Hunters at 130AM) with well-defined outflow cirrus bands. Tuesday evening, TRMM, NASA's tropical research satellite, flew directly overhead Irene, getting a radar scan of the storm using it's downward pointing radar, shown in Figure 2. It is immediately apparent that Irene has well-developed bands of rain showers, with strong storms present in the eyewall.


Figure 1 IR satellite view of Irene taken at 113AM EDT, August 23, 2011


Figure 2 TRMM radar overpass of Irene at 713PM EDT, August 22, 2011. Image courtesy of the Naval Research Laboratory

Track Forecast

Irene is forecast to move to the northwest, passing over all of the Bahamas by Thursday evening, then curving to the north. Irene then makes landfall in the US near or at the Outer Banks Saturday afternoon, then traveling along the mid-Atlantic coastline of the US. After Saturday, Irene may pose a threat to Long Island and the New England coastline. However, NHC is quick to remind us that the average forecast error for day 4 is 200 miles, so don't stop your hurricane preparations if you aren't in the immediate area of landfall. It is also important to note that the windfield of Irene is expected to be large, affecting areas distant from the immediate track of Irene's center. Tropical storm forces winds are expected to be found out to at least 150 miles away from Irene's center on Friday afternoon.

NHC is forecasting for Irene to become a major hurricane (winds faster than 110 mph), within 24 hours.


Figure 3 Official track forecast of Irene at 2AM EDT.

Forecast models and adaptive observations
The different forecast models are in fairly good agreement about Irene's track through the Bahamas and along the east coast of the US. The GFDL, a dynamical hurricane forecasting model, which had been a western outlier from the other models is now agreeing with them. When a set of weather models using slighly different initial views of the atmosphere and slightly different ways of simulating how the atmosphere works all agree on a forecast, then meteorlogists tend to believe that the forecast is more likely to occur. The 00Z GFS and ECMWF (wind swath shown in Figure 4) forecasts are nearly identical, which furthur boosts forecaster confidence.

In the 11PM forecast discussion, the NHC forecaster praises the NOAA Gulfstream IV (aka Gonzo) for providing infomation about the atmosphere around Irene that will influence it's track. Looking at the plan of the day valid for today, it will be a busy day for airborne reconnaissance. Three flights for the Air Force hurricane hunters, two flights for the Gulfstream IV, and two flights for NOAA 42, a WP-3D (aka Kermit).


Figure 4 Plot of the maximum sustained winds in mph over the next week from the 00Z ECMWF forecast.

Impacts

In the immediate future, Irene will have a significant impact on the Bahamas and surrounding islands. Hurricane force winds are ongoing over the Turks and Caicos islands and southeastern Bahamas. These locations can expect storm surges that are 5-8 feet above tide levels. The northwestern Bahamas can expect hurricane force winds Thursday, and storm surges that are 7-11 feet above tide levels. The Turks and Caicos islands and all of the Bahamas can expect 6-12 inches of rain over the next two days.

I still think people living along the east coast of the US should closely monitor Irene and review their hurricane preparations. Irene will be a large storm, impacting areas far from the storm center track.

Dr. Masters will have a new blog entry this morning, and Angela Fritz will be covering the afternoon. I'll be back on third shift tonight.

Thanks for reading,

Dr. Rob Carver

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What a monster Irene is, moving NW, finally made the turn,hope everyone in her path is prepared, Irene could be a history making hurricane, JMO.
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977. hamla
are their any ham radio operators on wu or did amateur radio go away via computers,cell phones back in the day we were the only ones that could pass on info from distant places for health and welfare when storms hit and power was out.
any comments?

"N1RG" call sign amateur radio operator since 1957
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Correction to my last comment...it's WOBBLING along the tropical forecast points.
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Quoting interstatelover7165:
Currrent ACE is 6.92
Thanks for that - can I ask where you find the number?
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Quoting flsky:
Go to Google Maps and get directions between the two - it will give you the mileage.



What I wanna know is...How far west of NY is Miami?
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Quoting presslord:



Does the phrase 'certain death' ring a bell?


Yes, I believe that was one of the phrases used. Over and over and over again. And some people still didn't listen.
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First rainbands (for me) coming! Nassau, bahamas getting 30 mph gusts now.
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Product: NOAA Vortex Message (URNT12 KWBC)
Transmitted: 24th day of the month at 14:11Z
Aircraft: Lockheed WP-3D Orion (Reg. Num. N42RF)
Storm Number: 09
Storm Name: Irene (flight in the North Atlantic basin)
Mission Number: 13
Storm Number & Year: 09L in 2011
Observation Number: 27
A. Time of Center Fix: 24th day of the month at 13:44Z
B. Center Fix Coordinates: 22°13'N 73°39'W (22.2167N 73.65W)
B. Center Fix Location: 170 miles (273 km) to the WNW (288°) from Cockburn Town, Turks and Caicos Islands (GBR).
C. Minimum Height at Standard Level: Not Available
D. Estimated (by SFMR or visually) Maximum Surface Wind: 94kts (~ 108.2mph)
E. Location of the Estimated Maximum Surface Wind: 11 nautical miles (13 statute miles) to the NE (52°) of center fix
F. Maximum Flight Level Wind Inbound: From 152° at 114kts (From the SSE at ~ 131.2mph)
G. Location of Maximum Flight Level Wind Inbound: 14 nautical miles (16 statute miles) to the NE (53°) of center fix
H. Minimum Sea Level Pressure: 956mb (28.23 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 14°C (57°F) at a pressure alt. of 2,447m (8,028ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 23°C (73°F) at a pressure alt. of 2,419m (7,936ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 14°C (57°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Open in the southwest
M. Eye Shape & Diameter: Circular with a diameter of 21 nautical miles (24 statute miles)
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Level: Other - Not surface, 1500ft, 925mb (if vortex is newer than about mid 90's; see note for more), 850mb, 700mb, 500mb, 400mb, 300mb or 200mb
O. Navigation Fix Accuracy: 1 nautical mile
O. Meteorological Accuracy: 1 nautical mile
Remarks Section:
Maximum Flight Level Wind: 114kts (~ 131.2mph) in the northeast quadrant at 13:40Z
Maximum Flight Level Wind Outbound: 77kts (~ 88.6mph) in the southwest quadrant at 13:47Z
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Bad times in the Acklins right now
Member Since: August 19, 2005 Posts: 5 Comments: 5450
Quoting indianrivguy:


for brother Overwash... Crystal Beach after Ike.



The storm surge arrived earlier than predicted by the trusted local forecaster Dr. Neil Frank and trapped many, dooming them to a rather unpleasant death. I recall that some credited Dr. Masters, and folks from this blog for giving evacuation advice that ultimately saved their lives. Does this apply to Grandpa? I dunno, but erring on the side of caution and safety would seem to me the smart course of action when failure to take timely action could mean death.


Exactly; all that "I'm a man and a man don't leave his stuff" can end actually meaning "A man has to die with his stuff when he don't understand limitations"
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hi all i'm new to all this. watching the news and the weather man says the BH could move back west and closer the FL, the last thing I want is that. so is he seeing something the modles don't?

thanks
Ang
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966. flsky
Go to Google Maps and get directions between the two - it will give you the mileage.

Quoting presslord:
Would someone please calculate and post the longitudinal distance between Miami and New York?!
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Quoting CloudGatherer:
What really worries me about this storm is the potential for a New England landfall. Irene is a fairly large hurricane, with an expanding windfield. I don't think her winds will be all that high by the time she reaches that far north, but I'm extremely worried about the potential storm surge - historically, the deadliest and most devastating feature of northeastern landfalls.

Where can I find the ACE for the storm? It's a better surge indicator than the peak eyewall winds.
Currrent ACE is 6.92
Member Since: August 18, 2011 Posts: 0 Comments: 994
Quoting dmh1026:

Did you see the report of people using up their non-perishable supplies because they are no longer in the cone? Hurricane Season ends on November 30th and not August 24th...


No, I missed that one. That's just downright... ughhhhh.
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What really worries me about this storm is the potential for a New England landfall. Irene is a fairly large hurricane, with an expanding windfield. I don't think her winds will be all that high by the time she reaches that far north, but I'm extremely worried about the potential storm surge - historically, the deadliest and most devastating feature of northeastern landfalls.

Where can I find the ACE for the storm? It's a better surge indicator than the peak eyewall winds.
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I'd like to see the majority of the NHC bashers accurately predict a storm and its path and destruction without "borrowing" resources that other people have posted.
If you don't like the NHC then don't listen to it.
99% of everyone on this site has no more authority than anyone else on this blog COMMENT section unles you can prove you have the creds to back up what you say or who/what you "borrowed" from.
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Quoting keisa90:


Wait a minute. People were told days in advance that the storm surge with Ike would be huge. People were warned in plenty of time to get out, so don't blame Neil Frank.



Does the phrase 'certain death' ring a bell?
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Advisory 1:



Current advisory:



She appears to be in her cone, very close to where she was forecast to be. just off to the right.
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Quoting Jax82:
Hopefully there is no one on Acklins Island, she's gonna pass right over.


300-400 people live ther.
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also....as for Emergency folks wanting a 7 day forecast...it's silly......even now, with a 5 day forecast, FEMA is spending millions hauling crap all over the Eastern Seaboard...it's like a Marx Bros movie...
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Quoting indianrivguy:


for brother Overwash... Crystal Beach after Ike.



The storm surge arrived earlier than predicted by the trusted local forecaster Dr. Neil Frank and trapped many, dooming them to a rather unpleasant death. I recall that some credited Dr. Masters, and folks from this blog for giving evacuation advice that ultimately saved their lives. Does this apply to Grandpa? I dunno, but erring on the side of caution and safety would seem to me the smart course of action when failure to take timely action could mean death.


Wait a minute. People were told days in advance that the storm surge with Ike would be huge. People were warned in plenty of time to get out, so don't blame Neil Frank.
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Quoting 69Viking:


I think all cones should have the line removed out past 3 days, this way everyone in the cone area knows to be aleart and prepared but not to worried just yet that they have to evacuate. At 3 days out it's more critical to make possible evacation plans so the line should be there.


To present the potential intensity, why not just color code the cone and remove the line.
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Quoting CarolinaHurricanes87:


Hoping for disaster? Im just saying when they CALL FOR DISASTER... for everyone from texas to the OBX, and 99% of the people in these areas receive NOTHING, it hurts long-term how serious people take the situations. Im glad I hadnt started preparing bc Id feel like a fool had I spent time and $ in an awful economy and end up with a cloudy day and big waves...

They sounded an alarm for a lot of people when there was absolutely no reason to do so. If they arent sure in a projected path, maybe they should consider widening the cone or delaying the release of the projections until they are a little more sure.


The official forecast has predicted for a while now that a US hurricane landfall was unlikely. Any hurricane passing through islands will have an uncertain trajectory. For the most part the forecasters got it right(so far).

It is irresponsible media and local politicians who always tend to exaggerate the threat.
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951. Jax82
Hopefully there is no one on Acklins Island, she's gonna pass right over.
Member Since: September 2, 2008 Posts: 1 Comments: 1261
I thought Earl was gonna recurve sooner than it did last year... I remember "Burmuda better watch out", and "It's gonna go between Burmuda and the East Coast"... but it just kept coming. It was a doom and gloom storm that barely missed us, I'm not complaining and hope that Irene does too!

Wish I could post the 5 day cone in motion, but didn't work, here's the Link
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Where's Levi, would love to have his update today.
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Quoting mojofearless:


After all the bashing New Orleanians got for not getting out, not being prepared, blah blah blah, it just really yanks my chain to see people like you on here talking about wasting money on supplies, etc etc etc.
YOU LIVE IN A HURRICANE-PRONE AREA. Just like I do. And it is YOUR responsibility to be prepared and self sufficient year after year after year. You should not be whining about wasting money, or glad that you didn't (it's peak season!!!), you should have this budgeted out EVERY year, and you should already have the majority of your supplies stocked by June 1.
I don't mean to come across like a shrew here, but seriously. This is the personal responsibility everyone along the Gulf Coast and Eastern seaboard should be taking seriously every single year. To do otherwise would be like living in Detroit without a snow shovel and sweating every single cold front. Oh! Thank God I didn't waste money on a snow shovel! That blizzard totally missed us and hit Flynt instead! Stupid meteorologists!

Did you see the report of people using up their non-perishable supplies because they are no longer in the cone? Hurricane Season ends on November 30th and not August 24th...
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Quoting RickWPB:
I think the NHC do a great job. We need to remember that Wx prediction is not an exact science. It's fluid with lots of variables. We have computer models that help speed up the analysis, but we need the PhD's to make the final word. I thank them for their service.

Interesting to note that so far in this satellite/radar loop that Irene is tracking slightly to the right of the cone center line.

14 hr loop


Looks to me on NHC sat imagery she is moving right on Tropical Forecast points...
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Quoting charlottefl:


1,110 miles as the crow flies.


Thanks!
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Quoting presslord:
Would someone please calculate and post the longitudinal distance between Miami and New York?!


They dont say longitudinal differences on their forecasts.... if that is the case then just about every storm will be forecasted from Miami or even western florida all the way through new england... meaning the forecast is meaningless. The idea of a 3 day cone with no center line is a great idea.
Member Since: August 4, 2011 Posts: 0 Comments: 631
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Quoting presslord:
Would someone please calculate and post the longitudinal distance between Miami and New York?!


New York coordinates:
latitude: 40° 44' North
longitude: 73° 55' West

Miami coordinates:
latitude: 25° 47' North
longitude: 80° 13' West
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Quoting presslord:
Would someone please calculate and post the longitudinal distance between Miami and New York?!


1,110 miles as the crow flies.

That was a hare south of Miami, using the ruler...
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Quoting Grandpato4:


There is a placeholder. My comment was simply that a certain island was only accessible by ferry. I do not understand how that is inappropriate.


admins can make mistakes, they are humans. I have mad some mistakes moderating forums before.
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Quoting ecrugger:
I think Jeremy Wheeler of WAVY 10 in Hampton Roads has a pretty good blog about what he thinks will happen. Link


Jeremy Wheeler simply looks at the GFS models and goes with that, He puts little thought or opinion into the info he relays, but that's the same for almost all the local weather people around the area here in Hampton Roads.
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Quoting nrtiwlnvragn:


Agree, forecasting track has improved significantly. My argument is that in 2000 a 72 hours forecast cone was acceptable and the current 120 hour forecast cone has the same equivalent error.



yea...but in 2000....we didn't have this blog ;-)
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Quoting floodzonenc:


Agree!
That might be the most useful information I have seen so far. Thank you!!
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Would someone please calculate and post the longitudinal distance between Miami and New York?!
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Quoting hurricanejunky:
On the anniversary of Hurricane Andrew...

Hurricane Andrew - Path Of Terror


oh my -- certainly does bring back the memories.
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Quoting wxobsvps:
Looks like 76W may be the western-most extent of Irene's path, before heading North and NNE.

Without significant building of the Bermuda high to her north, I can't imagine how this system gets to CONUS.
The steering maps look like it is building back in more than yesterday. Crown Weather has the maps.
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Quoting CarolinaHurricanes87:


Seems to me they were off by significantly more than 200-250 miles. How far away are Miami and NYC lol


Your logic is way off. It was supposed to hit Miami tomorrow. However tomorrow position will be 150 miles off the coast. Therefore the forecast is 150 miles off
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Quoting presslord:



but one could reasonably assume our forecasting skills have improved since 2000....and as for the EMC folks...I'm not real sure what good a 7 day forecast is if it isn't accurate


Agree, forecasting track has improved significantly. My argument is that in 2000 a 72 hours forecast cone was acceptable and the current 120 hour forecast cone has the same equivalent error.
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Quoting CarolinaHurricanes87:


Seems to me they were off by significantly more than 200-250 miles. How far away are Miami and NYC lol


BINGO!!
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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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