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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based upon my experience in watching hurricanes. The "Pin Hole" eye that Irene has now is the most dangerous eye since they normally come with rapid intensification. NOAA stated in hurricane Wilma that the hurricane had the dreaded pin hole eye. We remember Wilma.
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EWRC occuring now
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Hey all. Up at FSU now. Had an interesting ride up. I drove by a mini vortex in a feild next to I-75. The sucker tried to bring me in and nugded my car to the right a few inches. Never seen anything tornadic in person so it was quite an interesting experience.
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Irene has definitely picked up forward momentum.
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Irene is developing a good or decent southern/equatorward outflow channel/inflow spiral banding features finally, which have been absent her entire life span. Right now outflow is improving in all quadrants and dry air and shear is slowly loosening its grip on her. Category four or five potential is within reach.
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Quoting TropicalAnalystwx13:


What are you talking about? Millions to Billions of people watch the Weather Channel.


Billions? Really? That would mean over 600 million non-Americans actually care about the US weather enough to install a satellite which will receive TWC's signal. Try again.
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Quoting atmoaggie:
That and they don't have nearly as many regular wind events exceeding ~40 mph as the south. Lots of tree limbs and trees that haven't been as regularly tested, for the most part.

(Yes, I know there are exceptions, such as Mt Washington.)


And Cape Cod...
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I live in Indiana, there is a trough that is suppose to come thru Indiana around 1600 to 2400hrs, folks it's no where near Indianapolis,
The reason I mention this, is suppose to be the guiding feature that takes Hurricane Irene up the east coast,
Here is what I have to say, with the delay of the trough, this will have an impact on the track of Irene.
The forward speed of Irene will also have an effect on the track.The storm is 429 miles south south east of Miami Fl. the speed is 12 MPH or 35 hours away from landfall, the later the trough comes the further west the storm travels, which changes everything.
All need to watch this trough and it's timing to see if the models are correct.
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Quoting Gorty:
TWC has put all of southern New England in the extreme threat level LOL.


RATINGS...

Thats all they really care about.
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Quoting TropicalAnalystwx13:


Been closed long enough to undergo an Eyewall Replacement Cycle, lol.



Maybe so...We'll see.
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Quoting chicagowatcher:
Quoting nrtiwlnvragn:


We would also need Lefty, he may be lurking, was last year.



I miss lefty. Glad to see StormJunkie is still on from time to time.
So do I. So am I.

We did have a good core of bloggers here.
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The people would never get educated if scientists only talked to scientists.
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Levi, there is no way that 90L makes it to the Caribbean with a negative NAO right?
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Quoting presslord:


Far more frightening than Irene...


I will have to disagree with you on that with Craig Fugate at the helm. He was an excellent head of Florida's Emergency Management. I know you disagree.
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Quoting MississippiWx:


Here eye wall hasn't been closed for very long (assuming that it's finally closed). I doubt we have an ERC already.

Beautiful hurricane...



Been closed long enough to undergo an Eyewall Replacement Cycle, lol.

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1175. snotly
Quoting snotly:
category 3 winds will go over Long Island.


within the next two hours!!
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Quoting wpb:
y would anyone advertise on the twc nobody watches


What are you talking about? Millions to Billions of people watch the Weather Channel.
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Quoting Levi32:


Well on the current NHC track, Friday morning puts the storm east of Florida and gives New England 48 hours until landfall there.

It should be noted that the storm is currently moving faster than forecast, and if that continues, the timetable may be bumped up a bit.


::sigh:: Although its the truth, not exactly what I wanted to hear from you. Thanks!
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1172. wpb
Quoting atmoaggie:
I think you meant:
" We'll be back in 2 hours after these 48 commercials interspersed with 12 minutes of a documentary movie".
y would anyone advertise on the twc nobody watches
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Quoting DontAnnoyMe:
They've been officially warned!


FEMA To New England: Be Ready For Irene


Far more frightening than Irene...
Member Since: August 13, 2007 Posts: 0 Comments: 10492
Quoting MississippiWx:
If Irene were farther north right now, she would probably be in the same location as the upper low offshore of the Carolinas. In other words, if the steering currents didn't change, Irene would most likely end up where the upper low is currently. However, since the steering is going to keep changing as the trof approaches from the west and the high breaks down to the east, Irene's path will be farther east than the upper low as the steering currents are basically the same all the way up to 200mb. I think that gives us a good clue as to where Irene will eventually go.

What you say here indicates that they she'll continue to trend east which is a good thing for people on the coast. I hope that's what happens.
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1169. snotly
category 3 winds will go over Long Island.
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Quoting Ryuujin:


Because probably 70% of the New York/Boston/DC metro area aren't worried about it.


I don't believe that at all.
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Quoting notabubba:


"Jim Cantore here on top of the Fox Point Hurricane Barrier. The wind is so strong I can barely stan..."

"Jim? Jim are you there??" Ok, back to Joe in the studio for a storm center update!"
I think you meant:
" We'll be back in 2 hours after these 48 commercials interspersed with 12 minutes of a documentary movie".
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1166. Gorty
Quoting JonClaw:


Has TWC gotten THAT bad since I stopped watching it years ago?


Maybe they are onto something... they do have a former NHC hurricane specialist there.
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Quoting TropicalAnalystwx13:


I predict an eyewall replacement cycle very soon.
Indeed.

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1164. HiWay
Quoting newportrinative:


Jeez, people in NE are aware of the dangers of a CAT 1 or 2 Levi. This isn't the dark ages. In every scenario there will be those that do or don't take a storm seriously.


This is one the largest wind fields in recent history to potentially make landfall in NE. With the large size we will have a much larger surge than the usual smaller storms that make it up there. There is also the fact that as Dr. Masters mentioned the much warmer than average waters farther north. The usual fast deterioration of the storm in the NE waters won't be quite as fast unfortunately.
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1163. Levi32
Quoting daddyjames:


Thanks - just Friday may be a bit too late for some of them to get out if needed.


Well on the current NHC track, Friday morning puts the storm east of Florida and gives New England 48 hours until landfall there.

It should be noted that the storm is currently moving faster than forecast, and if that continues, the timetable may be bumped up a bit.
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1162. wpb
Quoting JonClaw:


Has TWC gotten THAT bad since I stopped watching it years ago?
un watchable x1000000
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That soil moisture map if full of crap, the ground is so saturated here in Central Florida that water is flowing out of open fields. Many spots have had over 10 inches this month and Ive had 15, we've only had 5 days out of the whole month without rain as well. Its acting like we are dry. Yeah, right.

Anyways though, I'm worried if Irene tracks into New England, and I'm most worried about the flooding potential more than anything.
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1138. CybrTeddy

That model plot shows the tracks of three storms.
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Quoting TropicalAnalystwx13:


I predict an eyewall replacement cycle very soon.


Here eye wall hasn't been closed for very long (assuming that it's finally closed). I doubt we have an ERC already.

Beautiful hurricane...

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1158. stexram
Quoting Abacosurf:
WOW!!

Been out in a boat all day.... Looks like the models have trended slightly west....is that true?

I was hoping she would clear east of Abaco but that does not look to be the case. Yikes.


Lets hope nippers makes it through without too much damage.
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1157. JonClaw
Quoting Gorty:
TWC has put all of southern New England in the extreme threat level LOL.


Has TWC gotten THAT bad since I stopped watching it years ago?
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1156. SLU
Damage reports coming from the Bahamas.
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Quoting NJcat3cane:
the last 3 frames have been almost due west..just a tad north of that


Its a wobble to the west with convection blowing up on her north side, overall movement is NW
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Has anyone compared its current location to the forecast NHC made 2 days ago? I'd like to do that, but don't know. Or compared the current forecast to the forecast 2 days ago. Both ideas are interesting.
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Quoting DontAnnoyMe:
They've been officially warned!


FEMA To New England: Be Ready For Irene


Talk about DOOM...
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1152. WxLogic
18Z NAM @24hr 500MB:

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1151. Bayside
Quoting sarahjola:
i bet everyone on the e. coast wishes this would hurry up and be done with. lol! i'm sure they are thinking " if its comming just hurry up and come, and if its not just hurry up and pass" all this anticipation is killing me, i can only imagine how they feel. waiting to make a decision on katrina was unbearable and katrina came way faster. there wasn't a week or more of but clinching. lol! wish the best for all on e. coast. hope it just goes away.


It's very unnerving... this morning it was trending more east and looked like it would clear us just barely... now all bets are off again...
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Nice pinhole eye on satellite imagery. Yeah, I said it.
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1149. Buhdog
GREAT SEEING THE OLDTIMERS TODAY! Irene still dub-steppin all the way up the islands I see. She is acting like a Slinky going uphill if that were possible! I am calling 945 mb by 11pm tonight!



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most likely irene will end up west of the next forcasted point...not set in stone yet tho
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Quoting kilgores97:


But the trough looks to be flattening out some, so that may not be an accurate depiction of where she will end up.


The trof is going to have its effects. It's not going to magically disappear. However, it will lift out to the north eventually and will probably leave a path just east or right on top of the Outer Banks.
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Quoting MississippiWx:


I predict an eyewall replacement cycle very soon.
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Quoting notabubba:


"Jim Cantore here on top of the Fox Point Hurricane Barrier. The wind is so strong I can barely stan..."

"Jim? Jim are you there??" Ok, back to Joe in the studio for a storm center update!"


funny....
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They've been officially warned!


FEMA To New England: Be Ready For Irene
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1143. Jax82
Quoting BahaHurican:
The eye is moving towards the next island up, Long Island, now. Initial reports from the South of Acklins beginning to come in.

I'm updating my blog as I get new information about local conditions, so you can check there for details.


Cant believe anyone would ride out the cane on Crooked island, that had to be a wild ride.
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1142. Gorty
TWC has put all of southern New England in the extreme threat level LOL.
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HPC Extended Forecast Discussion

Excerpt:

IN ADDITION TO IRENE INTENSITY IN GUIDANCE...ONE OF THE LARGEST
REMAINING UNCERTAINTIES IN THE MEDIUM RANGE PERIOD HOWEVER IS THE
EXACT SPEED AND STRENGTH OF A STRONG SHORTWAVE TROUGH CURRENTLY
ENTERING WESTERN CANADA. THIS TROUGH IS EXPECTED TO AMPLIFY DOWN
FROM ONTARIO/QUEBEC BY DAY 3/SAT AND PICK UP IRENE. THE GFS/ECMWF
HAVE NEARLY CONVERGED WITH THE DETAILS OF THIS TROUGH...WITH THE
GFS ONLY SLIGHTLY FASTER AND SUPPORTED BY THE CANADIAN...THUS
ACCELERATING IRENE NORTHWARD INTO THE NORTHEAST/NEW ENGLAND AND
BEYOND MORE QUICKLY THAN THE ECMWF. HOWEVER...RUN-TO-RUN
VARIABILITY WITH THE MORE UNCERTAIN HIGHER LATITUDE FLOW IS TO BE
EXPECTED...WITH RECENT GFS/ECMWF 4-CYCLE LAGGED AVERAGE FORECASTS
SHOWING 500 MB HEIGHT VARIABILITIES AVERAGING 50 TO 70 DECAMETERS
ACROSS THE UPPER GREAT LAKES...ENOUGH TO SUPPORT DIFFERING
INFLUENCES ON IRENE.

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1140. Levi32
The eye of Irene continues to undergo trochoidal oscillations, which is the "stair-steeping" effect people talk about. The overall motion remains northwest, with short-term wobbles ranging from west to north.
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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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