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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Quoting wxobsvps:


I'm not yet sold that SC/NC doesn't get landfall. Once we see where the weakness really is when the true North turn happens that will tell the tale better


Sorry I left out a key word for my question: Florida!
I live on the east coast of Florida, just north of Melbourne. Please reanswer with that qualification....Thanks!
Member Since: August 18, 2008 Posts: 0 Comments: 32
Quoting txag91met:


Regardless if it hits as a cat 1/2, there will be damage due the size and scope of this storm. Just watch and learn.


Watch and learn a sense of humor.
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You people need to learn when the sarcasm flag is on, lol.
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Quoting ProgressivePulse:



Still barely NW however, she will miss the next TFP by about 20 miles left and about 3 hours early, meaning Irene is moving faster than anticipated.


Meaning she'll brush closer to WPB, right?
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Quoting 996tt:
Leaving in the am for Cocoa and Sebastian Inlet and hoping Irene keeps her butt far enough off shore to send a nice 12 + swell without too much blown out chop. Should be sweet when winds shifts and she goes by late Friday. She is now welcome to turn NE and stay off shore as much as possible. Heres to following those Eastern outliers and shift even further east.
bunch of closeouts so far
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1383. Levi32
Back later.
Member Since: November 24, 2005 Posts: 628 Comments: 26455
Quoting ecupirate:


What does that have to do with the price of Tea in China?

Not sure, but at least as much as 127 posts about the cast of Jersey Shore vis-a-vis Irene's approach. ;-)
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Quoting PaulinJax:
I know we hear about sterring currents etc , but when exactly will she start to turn ?

At 11:28:21 p.m. GMT tonight.
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1378. Levi32
Quoting CarolinaHurricanes87:


Levi, does Wilmington being in "the cone" mean we are still a possible landfall location... or just means we could receive major impacts but not a direct hit?


The cone represents the typical error of the NHC forecast as it goes out in time, where historically, the storm stays within the cone 70% of the time. A good rule of thumb is that if you're in the cone, then you are a possible landfall location and should keep a very close eye on the storm. However, we have seen many storms where the entire cone missed where the storm actually tracked, so it's not a hard rule. Here, I think the current cone is a pretty good representation of what the risk area is along the eastern seaboard.
Member Since: November 24, 2005 Posts: 628 Comments: 26455
1377. Gorty
Quoting TropicalAnalystwx13:


A major hurricane that should become a Category 4 hurricane tomorrow and then scrape NC as a 2/3 and then the NE as a 1/2.

Nothing too significant...


Right because 1/2 category is not significant for NYC and New England... Please don't mislead people.
Member Since: November 8, 2008 Posts: 12 Comments: 1058
Quoting atmosweather:


She has already begun to turn NW, and she will likely begin a NNW-ward turn sometime tomorrow, with a more N-ward motion late tomorrow night or Friday morning.


She's been on that course all day, though the track is slightly west of the NHC plots. It's wait and see on the turn. Just because the NHC says it will doesn't make it so, especially with the flattened trough and nudging in of the Bermuda high.
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Quoting oakland:


We had it all in Ellenton. Lightning, heavy rain, strong winds....


I'm on Terra Ceia Bay. Looks like another round in early evening. I opened my windows for the first time in months last night.
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Irene looks to me like she is moving faster than the NHC track shows. Pretty much on track though.
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1373. Dakster
Quoting Tazmanian:
the storm is comeing closeer and closer too FL evere day and it still have not seen march of a turn


?? Confused ??

Seems to be following the NHC tracks to me...
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Quoting TropicalAnalystwx13:


A major hurricane that should become a Category 4 hurricane tomorrow and then scrape NC as a 2/3 and then the NE as a 1/2.

Nothing too significant...


Regardless if it hits as a cat 1/2, there will be damage due the size and scope of this storm. Just watch and learn.
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Quoting Neapolitan:
Slightly off-topic, but something Dr. Masters wrote of extensively a few months ago: it turns out that the Wallow Fire--Arizona's largest ever--wasn't set by illegal immigrants (as so many were far too quick to assume), but by a pair of camping brothers who failed to properly extinguish their breakfast blaze.

840 square miles of forest destroyed just for eggs and a pot of coffee. Nice...


One natural disaster caused by a couple of others.
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This is a randomly picked street view from Chatham MA. It won't take a well trained eye to see why cat1 will do as much damage up there as a Cat3 would in FL:

Link

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Quoting Gorty:


Cause, who would of guessed western CT and western Mass would also be in it? I thought they would just keep me in high. Leading to believe I will receive stronger winds and more rain now than previously expected.


Well I just hope everyone in it's path takes it seriously. I've lived through several living in the Florida Panhandle and trust me even a Cat 1 can wreak havoc when it brings down a lot of rain and wind gusts over 120 mph. If this storm rides the Gulf Stream with higher than normer water temps in the NE it could easily roll in as a strong Cat 2 or minimal Cat 3, there's just no telling right now how it's going to play out and people need to take it seriously. Best of luck.
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Quoting Neapolitan:
Slightly off-topic, but something Dr. Masters wrote of extensively a few months ago: it turns out that the Wallow Fire--Arizona's largest ever--wasn't set by illegal immigrants (as so many were far too quick to assume), but by a pair of camping brothers who failed to properly extinguish their breakfast blaze.

840 square miles of forest destroyed just for eggs and a pot of coffee. Nice...


What does that have to do with the price of Tea in China?
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Quoting Jedkins01:


Yeah you must have! It was an impressive line.


I was out running in that. Got out of the car, looked at the sky and said 'I'll be done before that gets here.'

The good news is you feel really dedicated when you're running in the rain.

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This storm Irene hasn't entered into the warmest patch of water yet gulp.
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Slightly off-topic, but something Dr. Masters wrote of extensively a few months ago: it turns out that the Wallow Fire--Arizona's largest ever--wasn't set by illegal immigrants (as so many were far too quick to assume), but by a pair of camping brothers who failed to properly extinguish their breakfast blaze.

840 square miles of forest destroyed just for a couple of scrambled eggs and a pot of coffee. Good deal...
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Quoting MiamiHurricanes09:
When's the next recon going into Irene?


Kermit is on his way.

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Quoting WeatherfanPR:


I live in Carrollwood and yes we experienced that squall line with very heavy rain and lightning but no strong winds in my area.

Looks like you all in Tampa had more "weather" yesterday..I am up in Hudson in Pasco Co and only had a 14mph gust but the temp dropped nearly 10 deg in just minutes..awesome downdrafts!! Looking forward to a breezy day tomorrow with Irene influencing an overall drier than usual day in the Tampa Bay area..

Hudson, FL weather
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Quoting wxobsvps:
Significant northerly component to Irene's fwd motion shouldn't be expected today at all. That doesn't mean FL is in the crosshairs.

What is important is where the weakness between the ATL high and CONUS high gets established. Right now it is over the Eastern CONUS and western ATL.


But would you agree it increases our chances of at least a period of sustained TS force winds along the mid to south eastern coast?
Member Since: August 18, 2008 Posts: 0 Comments: 32
1359. Zaphod
Even generously assuming wobbles, the path sure looks to be a bit lower and faster than forecast. Not by much, though.

The initialization point seemed to be a little off too, with the storm starting just a tad N of the forecast point, but perhaps within wobble-range.

With at least four days of forecast range where a few miles may make the difference for millions of people, this will have a high interest factor for us and a huge pucker factor for public officials.
Member Since: October 5, 2005 Posts: 15 Comments: 3239
Quoting 996tt:


Yeah. Floyd different set up. I remember Floyd's swell. Nice Double over head barrels you could drive a truck through. Won't be that nice this go around due to Irene's path coming in. If Irene stay strong, she hopefully will be well of shore of CONUS and big waves will be her prime remembrence.
rats got blown out of the palm trees on that one
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1357. oakland
Quoting Jedkins01:


Strange, I live in Pinellas County, the rain and lighting was only short lived but we got blasted by wind.


We had it all in Ellenton. Lightning, heavy rain, strong winds....
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Quoting NoVaForecaster:


PLEASE let that happen, I would like nothing more than to see those morons get washed away for good!


I know your just joking.. but my elderly Mother lives there on the southern jersey shore (the real one)..and No she doesnt wear a bumpit. I have seen what a n'oreaster does there.. can't even imagine a cat 2 or 3 hurricane..
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Quoting Levi32:


It looks like it will be by a bit, but as always, things can change. We saw it shift east. It could shift slightly west between now and then. We will be watching the turn that will be occurring in the Bahamas closely over the next couple of days to see if she is following the models or not.


Levi, does Wilmington being in "the cone" mean we are still a possible landfall location... or just means we could receive major impacts but not a direct hit?
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Quoting Bluestorm5:
Irene marching toward East Coast as monster Category 3 storm (almost 4) and expected to hit New York as a Category 1/2 hurricane.
Quoting TropicalAnalystwx13:


A major hurricane that should become a Category 4 hurricane tomorrow and then scrape NC as a 2/3 and then the NE as a 1/2.

Nothing too significant...

OK, not much.
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Quoting WeatherNerdPR:
FINALLY have power. What did I miss?


Welcome back Nerd....(you don't want to know) lol!
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Quoting GTcooliebai:
Wow! I must have really been knocked out not to hear anything.


Yeah you must have! It was an impressive line.
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1350. 996tt
Quoting TropicalAnalystwx13:


Think Floyd's landfall point is too far west for Irene?



Yeah. Floyd different set up. I remember Floyd's swell. Nice Double over head barrels you could drive a truck through. Won't be that nice this go around due to Irene's path coming in. If Irene stay strong, she hopefully will be well of shore of CONUS and big waves will be her prime remembrence.
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Quoting uptxcoast:
Shhhhh. Nobody tell the cast of Jersey Shore......


LOL!!!
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Quoting BobinTampa:
just checking in. Is Tampa in the clear now?



As long as you have those Indian burial grounds you are :)
Member Since: July 17, 2006 Posts: 0 Comments: 406
Quoting WeatherNerdPR:
FINALLY have power. What did I miss?


A major hurricane that should become a Category 4 hurricane tomorrow and then scrape NC as a 2/3 and then the NE as a 1/2.

Nothing too significant...
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Quoting Jedkins01:


Strange, I live in Pinellas County, the rain and lighting was only short lived but we got blasted by wind.
Wow! I must have really been knocked out not to hear anything.
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Quoting westFLtropics:


Yes, West Florida is in the clear. But we may get some gusty winds tomorrow and Friday.


Not even that, regular diurnal convective storms and slightly more breezy than usual.
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ON a quick break from work (in wilmington)... any change from this morning? Models looking the same or shifting slightly west? Feeling like we'll be ok but a jump west could put us right back in the cone... being on the west side of the storm by 70 miles and a cat 4 over my head is a pretty big difference, feeling safe but watching closely jw about any changes since this morning? TIA
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Quoting WeatherNerdPR:
FINALLY have power. What did I miss?
Irene marching toward East Coast as monster Category 3 storm (almost 4) and expected to hit New York as a Category 1/2 hurricane.
Member Since: August 1, 2011 Posts: 23 Comments: 7465
1342. Walshy
Levi32

Do you think its possible that Greensboro, NC and maybe areas slightly west will see clouds from Irene?
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1341. Levi32
Quoting TropicalAnalystwx13:


Think Floyd's landfall point is too far west for Irene?



It looks like it will be by a bit, but as always, things can change. We saw it shift east. It could shift slightly west between now and then. We will be watching the turn that will be occurring in the Bahamas closely over the next couple of days to see if she is following the models or not.
Member Since: November 24, 2005 Posts: 628 Comments: 26455
Quoting WeatherfanPR:


I live in Carrollwood and yes we experienced that squall line with very heavy rain and lightning but no strong winds in my area.
,had 40-50mph winds here in srq,i posted a couple pics,i also saw a funnel out over the gulf
,shuld get another nasty round in abouta hrs,thatbline yesterday was that outflow boundry that was assiocaited with the low tgat died off sc,thatboundry got pushed allthe way accrross the state..anyone in my area notice how cool it was after the storms last night it was only 71* !!!

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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.