Powerful Category 3 Irene enters the Bahamas

By: Dr. Jeff Masters , 3:49 PM GMT on August 24, 2011

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Powerful Category 3 Hurricane Irene stormed through the Turks and Caicos Islands overnight, bringing hurricane-force winds, torrential rains, and storm surge flooding. On Providenciales in the Turks and Caicos Islands, where half of the population of these islands live, winds reached a sustained 65 mph at a personal weather station at Pine Cay, and the pressure bottomed out at 989 mb. The eyewall of Irene missed the island, with the center of the storm passing about 60 miles to the southwest. The center of Irene passed about 60 miles to the northwest of Grand Inagua Island, and Category 1 hurricane conditions were probably experienced on that island. Damage in the Turks and Caicos is likely to be much less than the $50 - $200 million wrought by Category 4 Hurricane Ike of 2008, since Irene's eyewall missed populated islands.


Figure 1. Morning satellite image of Irene.

Monday, Irene hit Puerto Rico as a tropical storm with 70 mph winds, but reached hurricane strength as it emerged into the Atlantic northwest of the capital of San Juan. One drowning death is being reported from the island, and the storm dumped up to 20 inches of rain in some areas. About 11% of the island was still without power this morning, and numerous roads were closed due to flooding and landslides. Irene did an estimated $17 million in damage to agriculture and $2 million to ports in Puerto Rico. Satellite estimates suggest that Irene has brought only 1 - 2 inches of rain to Haiti. With Irene now pulling away from Hispaniola, Haiti can expect only another 1 - 2 inches from the hurricane, and appears to have dodged a major bullet. Heavy rains of 3 - 6 inches were common across the Dominican Republic, where moderate flooding but no deaths occurred.


Track forecast for Irene
Continuing dropsonde missions by the NOAA jet have helped to significantly narrow the uncertainty in the 1 - 3 day forecasts from the computer models. Irene will track through the central Bahamas today, the northwestern Bahamas on Thursday, and approach the Outer Banks of North Carolina on Friday. However, the models still diverge considerably on their 4 - 5 days forecasts, and we don't know if Irene will plow up the mid-Atlantic coast into New Jersey, as the GFDL model is predicting, hit New England between Long Island, NY and Massachusetts, as the ECMWF, GFS, and HWRF models are predicting, or miss the U.S. and hit Canada, as the NOGAPS model is predicting.

Intensity forecast for Irene
Latest data from the Hurricane Hunters shows that Irene has paused in its intensification cycle. A gap has opened in the eyewall, and the central pressure has remained constant at 956 - 957 mb over the past few hours. However, the hurricane is 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 storm sometime in the next two days. Satellite loops show that Irene is well-organized, with excellent upper-level outflow, and impressive spiral banding.

Irene's impact on the Bahama Islands
Irene is making a direct hit on Crooked Island (population 350) in the Bahamas, and will continue west-northwest and hit Rum Cay (population 80) and Cat Island (population 1700) late tonight. These unfortunate islands will bear the full brunt of Irene's 115+ mph winds and 8 - 13 foot storm surge, and suffer major damage that will take months to recover from. Major damage is also likely on Long Island (population 3000) and San Salvador Island (population 1000.) Shortly after midnight tonight, winds at the capital of Nassau, home to 70% of the population of the Bahamas, will rise above tropical storm force, and increase through the night. By late morning on Thursday, sustained winds will peak on Nassau at just below hurricane force, 60 - 70 mph. Nassau will miss the brunt of the storm, and I expect the airport should be able to re-open on Friday. Winds on Grand Bahama Island in Freeport will rise above tropical storm force late Thursday morning, and increase to a peak of 45 - 60 mph late Thursday afternoon. Grand Bahama will also miss the brunt of the storm, but Abaco Island to its east will likely experience Category 2 hurricane conditions Thursday afternoon. However, Abaco will probably miss the right front eyewall of Irene with the strongest winds and highest storm surge.


Figure 2. Wind distibution around Irene as of 1330 UTC (9:30am EDT) August 24, 2011. Irene was a Category 3 hurricane with 115 mph winds at the time. Hurricane force winds (yellow colors) extended over Crooked Island to the storm's northwest, and over Mayaguana Island to the east. Image credit: NOAA/AOML. Irene is a large storm, and its potential storm surge damage rated 3.9 on a scale of 0 to 6, with its wind damage potential rated at 2.5 on a scale of 0 to 6.

Irene's impact on the Southeast U.S.
Long-period ocean swells from Irene will reach the coast from Florida to North Carolina tonight, and continue to build as the storm approaches. The outermost rainbands of the hurricane will reach South Florida by Thursday morning, and spread over much of the eastern coastal portion of Florida during the day Thursday. If Irene follows the official NHC forecast through the Bahama Islands, the storm's expected radius of tropical storm-force winds of 130 - 170 miles will keep tropical storm conditions just off the east coast of Florida. Sustained winds of 20 - 30 mph can be expected along the coast of Florida during Irene's point of closest approach, and rainfall amounts of 1 - 2" will be common along the coast. Georgia, which could use the rain, will get very little. It is unlikely any airport in Florida or Georgia will need to close for Irene.

Late Friday night or early Saturday morning, Irene's outer spiral bands will move over the southern coast of North Carolina and the northeastern portion of South Carolina, and tropical storm-force winds of 39+ mph will arrive. Winds will steadily increase to hurricane force on the Outer Banks by Saturday night. The main damage from Irene in North Carolina will come from the storm's flooding rains of 4 - 12" that will fall in coastal areas. Fortunately, this region is under moderate to severe drought, so the damage will not be as severe as that experienced during Hurricane Floyd of 1999. Significant wind damage can be expected in the Outer Banks of North Carolina, and considerable storm surge damage may occur along the shores of Pamlico and Albemarle Sounds. If Irene's eye misses making landfall in North Carolina, total damage from the storm should be less than $200 million, and could be considerably less than that.


Figure 3. Sea surface temperatures for August 24, 2011. Temperatures of 26°C (79°F) are typically needed for a hurricane to maintain its strength (black line). This boundary lies just off the southern coast of New Jersey this year, which is much farther north than usual.


Figure 4. Predicted 5-day rainfall for the period ending Monday morning, August 29, at 8am EDT. Image credit: NOAA/HPC.

Irene's impact on the mid-Atlantic and New England
The impact of Irene on the mid-Atlantic and New England is highly uncertain at this point, because we don't know if the core of the storm will miss the coast or not. In general, the heaviest rains will fall along a 100-mile swath just to the west of where the center tracks, and the worst wind and storm surge damage will occur to the east. If the core of Irene stays offshore, the mid-Atlantic and New England may escape with a few hundred million dollars in damage from flooding due to heavy rains and storm surge. If Irene hits Long Island or Southeast Massachusetts, the storm has the potential to be a $10 billion disaster. Irene is one of those rare storms that has the potential to make landfall in New England as a Category 2 or stronger hurricane. It is difficult for a major Category 3 or stronger hurricane crossing north of North Carolina to maintain that intensity, because wind shear rapidly increases and ocean temperatures plunge below the 26°C (79°F) level that can support a hurricane. We do expect wind shear to rapidly increase to a high 30 - 50 knots once Irene pushes north of Delaware, which should knock the storm down by at least 15 - 30 mph before it reaches New England. However, this year sea surface temperatures 1 - 3°F warmer than average extend along the East Coast from North Carolina to New York. Waters of at least 26°C extend all the way to Southern New Jersey, which will make it easier for Irene to maintain its strength much farther to the north than a hurricane usually can. During the month of July, ocean temperature off the mid-Atlantic coast (35°N - 40°N, 75°W - 70°W) averaged 2.6°F (1.45°C) above average, the second highest July ocean temperatures since record keeping began over a century ago (the record was 3.8°F above average, set in 2010.) These warm ocean temperatures will also make Irene a much wetter hurricane than is typical, since much more water vapor can evaporate into the air from record-warm ocean surfaces. The latest precipitation forecast from NOAA's Hydrological prediction center shows that Irene could dump over 8 inches of rain over coastal New England.


Figure 5. Soil moisture profiles from yesterday show that a region of very moist soils ranking in the top 1% in recorded history (dark green colors) lie over northern New Jersey, Southeast New York, and Northeast Pennsylvania. Image credit: NOAA/CPC.

Tropical storm-force winds and heavy rains will move into Eastern Virginia Saturday afternoon, and push northwards to Delaware and coastal Maryland by late Saturday night. Tropical moisture through a deep layer of the atmosphere will also stream well ahead of Irene into New England on Saturday afternoon and evening, bringing what is called a "Predecessor Rain Event" (PRE). The Washington D.C., Baltimore, and Philadelphia airports will be right at the edge of the heavy rain and high wind area, and it currently appears they will not have to close for an extended period. The Philadelphia and New York City airports may not be as lucky, and it is possible they will suffer extended closures Sunday morning and afternoon. By late Sunday night, Irene's rains will move north of New York City, allowing the airports to re-open. The highest potential for damaging fresh-water flooding is in northern New Jersey, Southeast New York, and Northeast Pennsylvania, where soil moisture is near record high levels, and there is nowhere for the rain to go (Figure 5.) Heavy rains of 4 - 12" are likely across all of coastal New England if Irene passes within 100 miles of shore.

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

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

Elsewhere in the tropics
A tropical wave far out in the eastern Atlantic about 200 miles southwest of the Cape Verde Islands, Invest 90L, is showing signs of organization. NHC is giving this disturbance a 50% chance of developing into a tropical depression by Friday. Several of our models do develop 90L into a tropical storm by early next week, but long-range models are showing that this system will not be a threat to any land areas over the next seven days, and will probably move too far north to ever be a threat to land.

Internet radio show on Irene at 4:30pm EDT today
I'll be discussing Hurricane Irene on a special edition of our Internet radio show, the Daily Downpour, today (Wednesday) at 4:30pm EDT. Fellow wunderground meteorologists Shaun Tanner, Tim Roche, and Angela Fritz will also be there. Listeners can email in or call in questions. The email address to ask questions is broadcast@wunderground.com.

Jeff Masters

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290. IMA
Quoting tropicofcancer:
Quoting swampdawg:No, not sadists.........just living in areas that are in need of RAIN in the WORST WAY!! And if a hurricane skirts the coast and brings us RAIN then THANK YOU JESUS!

Jesus cuts my lawn every 2 weeks here in South Miami. Why you are thanking him for potential rain in SC is beyond me, but I will let him know next time he comes.

Post of the day!
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Quoting FLdewey:
Has anyone seen Reed?
He was on this morning forecasting a CAT2 for Long Island, if I remember correctly.

EDIT: Reed responded #313, updated and corrected.
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Quoting E46Pilot:
As the storm makes it's closest approach to SE FL tomorrow, the weather will be amazing, as it sucks all of the moisture out of the air, it will be sunny, dry, and breezy. Another day in paradise.


Will be an incredibly great day for some kite-boarding!
Go to the beaches and watch it.
Member Since: May 31, 2007 Posts: 0 Comments: 1210


Here comes the trough diving southeast towards the Great Lakes.
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Quoting CCSoFLA79:


in 36 hours wouldn't she be on top of us? And if the NHC suspected Tropical forrce winds they put up a Watch for 36 hours in advance. So why haven't they. Seems to me like they do not expect it. Ain't gonna happen


supposed to and doing it can be two different things...storms ramp up and change all the time...i mean think about it...Irene BECAME a hurricane while on TOP of PR...little late to change a watch/warning etc
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Quoting lennykat4:



Oh my apologies... it'll just jump out of the ocean-- decrease in intensity because of the lack of water and leave Charleston on inland spared and make landfall in Greensboro, NC.


ok now you are being really stupid and I dont find you amusing.
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Quoting marknmelb:


X2


exactly

I swear I am tired of people looking at the "westward" team here on the blog. They treat most of us like we are plain crazy but there are a group of "northwards" as well that stare at the radar and sats for that northward turn. Just as soon as it shifts north they start screaming that it is turning and even some start going to the extreme side and claiming out to sea.

NOAA themselves stated that the storm had turned NW but it looked more like a wobble to me. Yeah they say our westward movements are wobble but how long can it wobble before it is a westward moving storm? If you look at the motion since 5 AM you see the following...

A WNW motion and then a northward jog at 8 AM making for the NW motion before you get another turn to the left and what looks to me to be a WNW motion once more.
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Quoting stratocat:


I'd join you in hoping that, if I could somehow put you in a jon boat in Charleston Harbor when it hit.



At least you are not as mean as the other guy.
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Quoting scCane:


Look at her just zoom to the nw


Yea - 60 is the new "40" - and NW is the new WEST
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IRENE MAYBE ABLE TO BUSSPUMP THE TROUGHRIDGE AND AND CONTINUE WEST LOL
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Quoting WeafhermanNimmy:


Calm down! Its not going to be that intense when it makes landfall in Greensboro, NC. It's wishcasting that's all that's highly unlikely to happen. Take a chill pill! You act like the whole world is ending.



Oh my apologies... it'll just jump out of the ocean-- decrease in intensity because of the lack of water and leave Charleston on inland spared and make landfall in Greensboro, NC.
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Surprised no one has compared Irene to Frances yet.
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Quoting cat5hurricane:

Right down the beach from you. Vanderbilt Beach.


Awesome, I live over by Immokalee Rd. and 951.
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Quoting tiggeriffic:


and i DID NOT LISTEN TO THEM...i was laughed at when buying stuff...told i was nuts...then the same people knocked on my door wanting what i had cuz they were not prepared...go figure...by no means am i saying we are gonna take a direct hit from Irene...don't get me wrong...but i am saying models can be wrong and you should ALWAYS be ready

Me too Tigger. I had everyone backup computers and take the disks with them. We took the lower file drawers out of the cabinets and placed on desks etc. Covered the computers with plastic. That was tuesday? or wednesday? I believe. We made it into a clean up day. At that time Hugo was supposed to make land fall as a Cat 2 on a Saturday but came ashore Thursday night. (do not remember where the land fall was supposed to be) Long time ago - so I might be a bit rusty on the timing. But forecasting HAS come a long way - and I am feeling confident. Still keeping both eyes on Irene and 77W
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The western movement seen on satellite imagery maybe be due to the upper level confluence between Irene upper level anticyclone and the upper level trough whose axis is positively oriented across the Panhandle of FL.
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GFS Keeps trying to develop something in the NW Carib / GOM in the wake of Irene. There could be a potential residual energy moving into the NW Carib/GOM and developing from from there.

We'll see what's left behind once Irene exits the Mid ATL region
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Quoting WeafhermanNimmy:


I am so hoping this moves into Charleston, SC. So we can get some good impacts in Greensboro, NC. Hoping praying to god! We need the rain!


I'd join you in hoping that, if I could somehow put you in a jon boat in Charleston Harbor when it hit.
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Quoting KEHCharleston:

Isn't Charleston at approximately 32N 80W? Wouldn't that be close enough to feel effects? The NHC track has been right on for awhile now; so I am watchful - not worried. I will be even more "watchful" if it goes much farther west than 77W. However, I have a good amount of confidence in the NHC and you all are the BEST!


32N 80W is the actual location of Charleston, if it did that then it would be a head on like Hugo...not seeing that per-say, but don't even want it to get to 78W...little too close for comfort having been knocked out of the cone...
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Quoting rkay1:
Okay? The ocean will get a little bumpy.  Whats your point?



My brother Floridian - De Nile is in Egypt
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09L/MH/I/C3
RI FLAG (FLAG)
MARK
25.00n/75.00w forecast point





ALWAYS FOLLOW NHC/TPC FORECASTS FOR ALL WARNINGS REGARDING THIS STORM
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Quoting Joe Bastardi:

"Keep in mind the worst ne US storms stay offshore till New England"

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Quoting rkay1:
Near Edison or Lely?



Sorry, what do you mean Edison or Lely?
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I wish people would realize that even if you don't take the storm right on your head, it can still cause some serious problems.

NHC Discussuin:

"HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 50 MILES...85 KM...FROM
THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 205
MILES...335 KM."

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Quoting swampdawg:No, not sadists.........just living in areas that are in need of RAIN in the WORST WAY!! And if a hurricane skirts the coast and brings us RAIN then THANK YOU JESUS!

Jesus cuts my lawn every 2 weeks here in South Miami. Why you are thanking him for potential rain in SC is beyond me, but I will let him know next time he comes.
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259. ADCS
Quoting Drakoen:
Don't even think it is physically possible for Irene to come much farther west, unless she "busts the trough" and "pumps the ridge"


I thought you have to pump the ridge before you can bust the trough?
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Quoting RampagePCFL:


I have no idea where you are from, but unless you went through all the "Best" forecasts with Andrew that claimed it was going some place else. Or even the more recent "Best" forecasts for Charley that had it NOT hitting below Tampa the whole time, take it easy. These things don't always follow the "Best" forecast and we here in Florida have some experience with the "Best" forecasts that haven't panned out.


X2
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Quoting rkay1:
FT Myers?



No, Naples.
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Quoting rkay1:
You know what else could happen but won't? About a million other things.



LOL!
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Quoting TruthCommish:


Iceland watch out!


Sarah Palin could see Russia form Irene's eye.
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Quoting CothranRoss:
IT WOBBLED NORTH! AT THIS RATE IT WILL HIT BERMUDA!!!


Iceland watch out!
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Quoting lennykat4:



Okay, so I don't post hardly ever but I read this blog daily and this statement is totally uncalled for.

I mean really, there are 227 air miles between Charleston, SC and Greensboro, NC (assuming hurricanes don't take the interstate-LOL)-- you REALLY would sacrifice the lives, homes, history of Charleston, SC so you can have greener grass?

I'm sorry, blog, but these kind of statements really ruin my educational experience that I recieve from this blog- especially when I have 100 year old property full of memories looking to go down the tube AKA Hazel (1954) in just a few days.

Jeez- that really got under my skin. And oh by the way? God is spelled with a capital "G".


Calm down! Its not going to be that intense when it makes landfall in Greensboro, NC. It's wishcasting that's all that's highly unlikely to happen. Take a chill pill! You act like the whole world is ending.
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Quoting E46Pilot:
As the storm makes it's closest approach to SE FL tomorrow, the weather will be amazing, as it sucks all of the moisture out of the air, it will be sunny, dry, and breezy. Another day in paradise.


Very true, right after one of these passes, they bring beautiful weather.
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119 FtLauderdale55 "So for any thinking person to proclaim that Florida coastline land mass is out of the picture to me - is wishcasting."

Or Texcasting, which rhymes with hex-casting... and oughtta work just about as well.
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Quoting rkay1:
FL



Cool, me too. SW FL lol
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Quoting nrtiwlnvragn:
GFS last four cycles, most recent red




Looks like the only/best chance of landfall is east Long Island.

Further strengthening will push the cone east as well.
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Quoting rkay1:
omg!? it might happen again!! FL put up your shutters!!



I have no idea where you are from, but unless you went through all the "Best" forecasts with Andrew that claimed it was going some place else. Or even the more recent "Best" forecasts for Charley that had it NOT hitting below Tampa the whole time, take it easy. These things don't always follow the "Best" forecast and we here in Florida have some experience with the "Best" forecasts that haven't panned out.
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Quoting hahaguy:


Actually from what I've read they had andrew hitting around jupiter before the ridge pushed him due west.


absolutely correct! A divergence ov approx 95 miles - and in spite of similar reliance on the Bermuda High and expected frequency influences
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Quoting RavensFan:

haha yes we do! but not all of us are florida casters lol. some of us have actually been watching all of the model runs and KNOW that Irene will not be making any unexpected turns westward!


It is kinda of foolish for people to think they "KNOW" what a storm will do. Unless you are god then you don't know what she will do. The weather is unpredictable but let tell you what I have been noticing. Irene has been wobbling westward for the past day or so and anymore wobbles will take her to the left of the forecast track. If you put the storm into motion and add the NOAA forecast track you can logically see that the storm's current movement would take it off course if it continued in this direction for a long period of time.
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Quoting CCSoFLA79:


in 36 hours wouldn't she be on top of us? And if the NHC suspected Tropical forrce winds they put up a Watch for 36 hours in advance. So why haven't they. Seems to me like they do not expect it. Ain't gonna happen


They're not expecting it, but it could happen...
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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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