Irene roars into life; may become the season's first hurricane

By: Dr. Jeff Masters , 12:03 AM GMT on August 21, 2011

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Tropical Storm Irene roared into life this evening, transitioning from a tropical wave to a 50 mph tropical storm in just a few short hours. An Air Force hurricane hunter aircraft in the storm was finishing up its mission when it suddenly came across a region with intense thunderstorms and surface winds of 50 mph. The aircraft found that a center of circulation had barely closed off on the southwest edge of this region, though the plane found almost no winds from the west around the circulation center. The 6:10pm EDT center fix found a central pressure of 1007mb, which is quite high for the observed 50 mph winds. Dry air to the north and west is slowing development, as well as moderate wind shear of 10 - 20 knots, as analyzed by the University of Wisconsin CIMSS group. Infrared satellite loops and radar out of Martinique show the storm is poorly organized, with no evidence of spiral bands. The center of Irene is expected to cross over the Caribbean island of Dominica early Sunday morning, but the heaviest thunderstorms lie to the north of the center, and will affect Guadeloupe, Antigua, and St. Kitts and Nevis.


Figure 1. Evening satellite image of Irene.

The computer models have shifted southwards since yesterday, and now take Irene south of Puerto Rico on Monday, and along the south shore of the Dominican Republic on Tuesday. On Wednesday, Irene should pass near or over southern Haiti, Eastern Cuba, and Jamaica. On Wednesday and Thursday, the models agree that a trough of low pressure will dip down over the Eastern U.S., which is likely to turn Irene to the north. The exact timing and strength of this trough varies considerably from model to model, and will be critical in determining where and when Irene will turn to the north. We can expect that Irene will impact Central Cuba, the Bahamas, and the Florida Keys on Thursday, but it is uncertain whether Irene's turn to the north will take the storm into the Gulf of Mexico or not. Irene most reminds me of Tropical Storm Fay of 2008. Fay formed just off the coast of Puerto Rico, and was never quite able to get organized enough to become a hurricane, due to passage over Hispaniola and Cuba. Fay topped out as a strong tropical storm with 70 mph winds, and did over $500 million in damage in the U.S., mostly due to flooding rains in Florida that accumulated to over 25 inches in a few areas. Fay also dumped heavy rains on Hispaniola, triggering flooding that claimed eight lives.


Figure 2. Track of Tropical Storm Fay of 2008.

Irene will be battling dry air and moderate wind shear of 10 - 20 knots through Sunday, and it will take the storm 1 - 3 days to build up an eyewall and intensify into a hurricane. Irene is more of a threat than Tropical Storm Emily of early August was, since Irene has closed off a center farther east than Emily did and has more time to organize before encountering Hispaniola. I don't think passage over Hispaniola will destroy Irene, since it is a fairly large storm, and is likely to be a hurricane by then. However, if Irene follows the NHC forecast, it will have an extended encounter with Hispaniola and Cuba on Tuesday through Wednesday that will probably weaken the storm below hurricane force. Keep in mind that the average error for an official 5-day forecast from NHC for a developed storm is 200 - 250 miles. Irene could easily miss Florida and move up the East Coast and hit North or South Carolina, or pass through the Florida Keys and into Gulf of Mexico, ending up who knows where. Given the uncertainties, this weekend would be a good time to go over your hurricane preparedness if you live anywhere in the Caribbean, Bahamas, or U.S. coast, since Irene could well be paying you a visit as a tropical storm or hurricane sometime in the next week.

Harvey hits Belize
Tropical Storm Harvey made landfall at 2pm EDT on Saturday near Dangriga Town, Belize, as a tropical storm with 60 mph winds. Harvey continues to dump very heavy rains on northern Guatemala, Belize, and portions of Mexico's Yucatan Peninsula as the storm tracks westwards at 12 mph. Dissipation is expected Sunday as the storm pushes inland. Harvey was a small storm, and the strongest winds were confined to a short stretch of coast near where the center came ashore. Winds at Belize City, Belize on Saturday topped out at 15 mph.


Figure 3. Radar image of Harvey taken at 11:30am EDT on Saturday, August 20, 2011, a few hours before landfall in Belize. A small closed eye is visible just south of the offshore islands of Belize. Image credit: Belize National Meteorological Service.

An exceptionally active early part of hurricane season
It's been a strangely hyperactive season for weak storms in the Atlantic so far this year. Tropical Storm Irene is the 9th named storm this year, and its formation date of August 20 ties 2011 with 1936 as the 2nd earliest date for formation of the season's 9th storm. Only 2005 had an earlier date. The first eight storms this year have stayed below hurricane strength, making 2011 the first hurricane season since record keeping began in 1851 to have more than six consecutive tropical storms that did not reach hurricane strength. As I discussed in Friday's post, a major reason for this is the lack of vertical instability over the tropical Atlantic so far this year. We've had a large amount of dry, sinking air over the tropical Atlantic, and the usual amount of dry, dusty air from the Sahara, both helping to keep the atmosphere stable and stop this year's storms from intensifying into hurricanes. Hurricane activity typically ramps up big-time by August 20, with more than 80% of all the hurricanes and 65% of all the tropical storms occurring after that date. At our current pace, 2011 will become the second busiest Atlantic hurricane season on record, with 24 - 27 named storms. There are only 21 names in the list of names for a hurricane season, so we may have to break out the Greek alphabet again in late October this year, as occurred in 2005. Ironically, this was the last time the current set of names was used in the Atlantic, so 16 of this year's 21 names are repeats of 2005. I'm not too happy about seeing another hurricane season challenge the Hurricane Season of 2005 in any way, and let's hope we don't retire another five names this year, like occurred in 2005! With vertical instability much lower this year than in 2005, and that year having already seen one storm (Dennis) retired by this point in the season, I doubt that will happen, though.


Figure 2. The annual cycle of average hurricane frequency in the Atlantic. Historically, about 35% of all the tropical storms and 15% of all the hurricanes will have occurred by August 20.

Invest 98L near the Cape Verde Islands
A tropical wave near Cape Verde Islands off the coast of Africa, Invest 98L, is spreading heavy rains and strong gusty winds to those islands today. So far this morning, top sustained winds measured in the Cape Verde Islands were 23 mph at Mindelo. 98L has a long stretch of ocean to cross before it could affect any land areas. Approximately 70 - 80% of all tropical cyclones that pass this close to the Cape Verde Islands end up curving out to sea and not affecting any other land areas, according to Dr. Bob Hart's excellent historical probability of landfall charts. The latest set of long-range model runs go along with this idea, and I'd be surprised if 98L threatens any land areas.

Jeff Masters

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Quoting KEEPEROFTHEGATE:
you do know hurricanes can exceed 200 mph right strip the land of everything even life so that nothing remains not but the dirt and the water


Wind over 200mph turns it into a Black hole Cane.... nothing escapes from it.... ;-)
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Quoting BenBIogger:


Looking for the article I had a while ago.

bad visibility according to an airport staff member.


Found the article.
"Resolute resident Doreen McDonald said she was listening to music when her husband heard a large explosion. They looked outside, but could see nothing. The whole of Resolute was blanketed in a thick fog.

“I don't know why anyone would risk trying to land in those conditions,” said Ms. McDonald, who runs the airport gift shop."




Link
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Quoting weatherjr:
People, models are not madamas or crystal balls which predict the future. (of course, they do not exist). To me it makes NO sense the hypercane some of the models are forecasting for the USA and some west caribbean islands. , even without land interaction.


of course it makes no sense to you, you said this wasnt even a TS after it was one

you said recon would be wasted
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Quoting ncstorm:
Frank Strait of Accuweather said if this comes over west of Florida that NC/VA will have a decent outbreak of tornados..
As if April 14-16 wasn't enough... that EF3 tornado in Sanford almost killed my grandparents and another EF3 almost hit my town at I-40/I-95.
Member Since: August 1, 2011 Posts: 28 Comments: 8075
Quoting beell:


GFS and UKMET build the A/B ridge farther to the west. Regardless of initiation being too far south.


The GFS has a ridge extending farther west than the Euro, yes, but a large enough weakness is still present so that Irene only impacts the eastern Gulf.

In other words, the GFS doesn't appear to be an outlier among the consensus.
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Dry Air is not a real problem anymore. Irene has made her on Moisture.





Looks like Shear is currently about 10-15kts....


Overall i would say Irene will probably become a Hurricane over the next 2 days fairly easily.
Member Since: September 2, 2007 Posts: 179 Comments: 20448
Quoting floodzonenc:
Oh my... :P



I'm not claiming that..LOL!!
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Quoting Thrawst:


What the models show us tonight is definitely worrying me right now... a lot more than what I had in mind.


It's worrying me too. I'm living in South Florida, and if Irene does become a Cat. 4 or 5, I'm heading north.
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Quoting Levi32:
We even have the NOGAPS going bonkers on intensity now despite land interaction all the way to Florida.
Yup. Thursday landfall:

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Quoting MoltenIce:
Something is telling me that there will be a Hurricane streak next...

Don't say that... The Caribbean and the SE US are at great risk, let them all be Tropical Storms.
Member Since: July 7, 2010 Posts: 0 Comments: 5725
Quoting WeatherNerdPR:
Seems it's almost guaranteed that IRENE will be our first hurricane, thus breaking the Tropical Storm Streak.


13 years since 1998 Georges
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Quoting washingtonian115:
Holy crap!.That's a 170mph hurricane.Let's hope that doesn't come true or else someone's gonna get the boot.
you do know hurricanes can exceed 200 mph right strip the land of everything even life so that nothing remains not but the dirt and the water
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405. beell
Quoting KoritheMan:


I checked to see if perhaps the initialization was too far south, but a homogeneous comparison of the NHC official track and the 18z GFDL reveal otherwise.

Still, it is most prudent for us to discount the scenario as unrealistic.


GFS and UKMET build the A/B ridge farther to the west. Regardless of initiation being too far south.
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404. MZT
Quoting WeatherNerdPR:
Seems it's almost guaranteed that IRENE will be our first hurricane, thus breaking the Tropical Storm Streak.

I'm still not convinced they really had to name all the tropical storms that they did, this year.
Member Since: September 24, 2005 Posts: 0 Comments: 793
Quoting ackee:
LOOKS like models shifting again would not be suprise if IRENE MISS HISPANOLA track between cuba and jam
It could take the doom and gloom track that some models insist between the Yucatan channel.That would not only make Irene our first hurricane.but potentially first major hurricane.Perhaps cat 4 or 5 storm.(Grinds teeth)
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Quoting Grothar:
HWRF 18Z



Nasty, dirty picture! Evil old man, although I have a feeling that you are younger than me :)
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Writing up a blog giving times of high tides for some areas that may be in Irene's path. New moon and perigee are less than 40 hours apart on August 29/30. This is not a perfect alignment, and Irene should affect the southeast before then. But tides starting on August 26 will be above normal and more so on Aug 27.
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Quoting KoritheMan:


I checked to see if perhaps the initialization was too far south, but a homogeneous comparison of the NHC official track and the 18z GFDL reveal otherwise.

Still, it is most prudent for us to discount the scenario as unrealistic.


Agree, it doesn't make sense.
Member Since: August 22, 2010 Posts: 0 Comments: 652
Quoting avthunder:
Hi - I am in Lighthouse Point too. Hoping the same thing. :) It looks like we are supposed to evacuate for a CAT 3 or higher (not that I think Irene will be one) - do you know if they really think storm surge could come in west of the intracoastal?


basing evacuation on SS Cat status is not wise..
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I think the center is pretty north, near by 16N
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Frank Strait of Accuweather said if this comes over west of Florida that NC/VA will have a decent outbreak of tornados..
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We even have the NOGAPS going bonkers on intensity now despite land interaction all the way to Florida.
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Quoting WeatherNerdPR:
Seems it's almost guaranteed that IRENE will be our first hurricane, thus breaking the Tropical Storm Streak.
Something is telling me that there will be a Hurricane streak next...
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Quoting ManicouRiverResort:
Located @ Dominica

Just had 2 small earthquakes as well. It never rains but pours.

Glad to see that most storm activity will be North of here.

We need a break.


Thanks for checking in and stay safe......Please keep us posted as you can as to conditions over there.
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Holy crap!.That's a 170mph hurricane.Let's hope that doesn't come true or else someone's gonna get the boot.
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Quoting WeatherNerdPR:

Thanks. Listening while I'm blogging.
to serve Sr!
Member Since: July 14, 2008 Posts: 0 Comments: 248
389. ackee
LOOKS like models shifting again would not be suprise if IRENE MISS HISPANOLA track between cuba and jam
Member Since: July 15, 2008 Posts: 0 Comments: 1376
Seems it's almost guaranteed that IRENE will be our first hurricane, thus breaking the Tropical Storm Streak.
Member Since: July 7, 2010 Posts: 0 Comments: 5725
Quoting barotropic:


I hope things workout. I am just south of you In Lighthouse Point. Just a few block from the inlet. I don"t want a hurricane! Plus, I have to drive my son to FSU wens. to get him up to his dorm. I guess I have to worry about the Panhandle also. If the storm appears to head our way I am sure you can find someone to help with shutters. Hopefully you wont need them though. Something tells me that even if we get the storm it will hopefully be indirect or on the weaker end of the scale. I hope1
Hi - I am in Lighthouse Point too. Hoping the same thing. :) It looks like we are supposed to evacuate for a CAT 3 or higher (not that I think Irene will be one) - do you know if they really think storm surge could come in west of the intracoastal?
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Quoting barotropic:


GFDL runs as if a trough doesn't exist? Yet, GFS has been showing it every run, for what 10 days?


I checked to see if perhaps the initialization was too far south, but a homogeneous comparison of the NHC official track and the 18z GFDL reveal otherwise.

Still, it is most prudent for us to discount the scenario as unrealistic.
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Located @ Dominica

Just had 2 small earthquakes as well. It never rains but pours.

Glad to see that most storm activity will be North of here.

We need a break.
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Thanks! (learning, clearly. lol)
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Quoting chrisdscane:
center still not under deep convection


You just said that a few posts back at 9:02 PM. Have some patience. It's like you expected something major to change between the 9 minutes you posted that lol.
Member Since: July 7, 2008 Posts: 2 Comments: 3237
Quoting FLdewey:


The cause of the crash near the Resolute Bay airport was not immediately known.


Looking for the article I had a while ago.

bad visibility according to an airport staff member.
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Quoting MoltenIce:
Not 145 mph - 145 knots
Ooooo wasn't reading that right then.
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Quoting caneswatch:


When models show it strengthening that high and it's this close, it's not to be taken with a grain of salt. It's to be taken seriously.


What the models show us tonight is definitely worrying me right now... a lot more than what I had in mind.
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Quoting TropicalWeatherGrl88:


Can I please have a link to this model run? TIA


Link
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Relocating COC?



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Quoting Levi32:


They probably propagated the old broad low pressure circulation that was down near 11N yesterday and didn't see the northward reformation coming. To us it was obvious, but the model doesn't always get it.
Somewhere over the rai..okay I got nothing.
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Quoting washingtonian115:
Mmmm 145mph storm.Well the ships model always goes over board with intensity.
Not 145 mph - 145 knots = 165 mph/265 km/h
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Member Since: September 2, 2007 Posts: 179 Comments: 20448
Quoting Stormchaser2007:
Grain of salt...

TVCN track with IVCN intensity is 128 knots over SFL.

GFDL has a Cat 5 in the GOM

HWRF has a Cat 4 near Miami

..Oof

FULL IMAGE (Recommended)


Not sure which one to pick, they all seem catastrophic.
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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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