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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Well, the intensity guidance sure is all over the place:

Member Since: September 2, 2009 Posts: 130 Comments: 21109
As I suspected NHC updated Irene and the new TVCN


AL 09 2011082100 03 TVCN 0 150N 590W
AL 09 2011082100 03 TVCN 12 161N 627W
AL 09 2011082100 03 TVCN 24 168N 658W
AL 09 2011082100 03 TVCN 36 173N 683W
AL 09 2011082100 03 TVCN 48 180N 705W
AL 09 2011082100 03 TVCN 60 188N 727W
AL 09 2011082100 03 TVCN 72 195N 745W
AL 09 2011082100 03 TVCN 84 203N 763W
AL 09 2011082100 03 TVCN 96 214N 779W
AL 09 2011082100 03 TVCN 108 228N 793W
AL 09 2011082100 03 TVCN 120 245N 805W
AL 09 2011082100 03 TVCN 132 264N 817W
AL 09 2011082100 03 TVCN 144 295N 814W
AL 09 2011082100 03 TVCN 156 311N 830W
AL 09 2011082100 03 TVCN 168 326N 839W
Member Since: Posts: Comments:
The 12z CMC doom solution also has the same hole that the JMA has. Look at where it has it tomorrow morning - way too far south.

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Quoting farhaonhebrew:
La Agencia para el Manejo de Emergecias ofrece conferencia de prensa veala en vivo:

Puerto Rico Emergency Managment press conference live Link

Thanks. Listening while I'm blogging.
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Quoting Levi32:


Even if I wanted to I couldn't, as I have a flight home in 2 hours. I'll have an update tomorrow morning.


Going back to Home-R! Have a nice flight & we'll look forward to some home cooked tid-bits!
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Quoting Vincent4989:

umm, Tampa, it's not 97L anymore.



Sorry i ment 98L.......LOL........the one off the Coast of Africa........Sorry
Member Since: September 2, 2007 Posts: 178 Comments: 20439
Irene's ULAC is slightly displaced to the south.Also, if Irene goes more north, weeelll, extreme suffering for Irene.
Member Since: November 13, 2009 Posts: 2 Comments: 728
Quoting KennyNebraska:


Why? The rigs and refineries in that part of the world have been closed by the EPA haven't they?


What are you talking about??? The Gulf produces a helluva lot of crude and natural gas. No refineries on the Gulf coast are shut down.

A hurricane in the Yucatan channel would push every petroleum price up quite a bit. Traders get spooked rigs and refineries will be shut down. And with that GFDL track/intensity - things would be taken offline.
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Quoting Levi32:


It's just the model consensus. If we followed that all the time 5000 miles of coastline would evacuate every time a storm was near. It would probably have to come pretty far east to get NC affected significantly. Georgia and SC still have to keep a close eye out if it comes up the east coast of Florida straight north into their states.


floyd..
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Quoting Hernando44:


That is not the real Jason posting! Can't even form sentences properly.
You are right. Also Jason limits his comments to 3 or 4 words bolded.
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Quoting TampaSpin:



Invest 97L appears nearly closed also.
It had been renamed few hours ago. Hurricane Hunter ran into TS force winds and it had closed circulation.
Member Since: August 1, 2011 Posts: 28 Comments: 7981
LLC is stil not under convection
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Man! all the models shifting up the spine and off the east coast of Fl, and im here just south of Cape Canaveral.
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Quoting watercayman:


South Sound area... you?
East End.
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Quoting Hurricanes12:
Why does the NHC base their track off the TVCN?


Because it's a compromise of all the models.
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That is not the real Jason posting! Can't even form sentences properly.
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This blog will be going crazy next week or so... gonna learn lots of new things as well :D
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Quoting ncstorm:


is this an east coast storm now?


It's just the model consensus. If we followed that all the time 5000 miles of coastline would evacuate every time a storm was near. It would probably have to come pretty far east to get NC affected significantly. Georgia and SC still have to keep a close eye out if it comes up the east coast of Florida straight north into their states.
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La Agencia para el Manejo de Emergecias ofrece conferencia de prensa veala en vivo:

Puerto Rico Emergency Managment press conference live Link
Member Since: July 14, 2008 Posts: 0 Comments: 248
Quoting presslord:


I know a nice girl in Cold Bay


Don't start lol.
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Quoting bocahurricane:


Oh he is definitely not cancelling the trip, it just makes me nervous being in the "cone of doom" and being alone. Obviously I am a serious tropical system watcher and will be monitering the situation closely.


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
Member Since: August 22, 2010 Posts: 0 Comments: 652
763

WHXX01 KWBC 210041

CHGHUR

TROPICAL CYCLONE GUIDANCE MESSAGE

NWS NATIONAL HURRICANE CENTER MIAMI FL

0041 UTC SUN AUG 21 2011



DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.

PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE

AND SUBTROPICAL CYCLONE INFORMATION.



ATLANTIC OBJECTIVE AIDS FOR



TROPICAL CYCLONE IRENE (AL092011) 20110821 0000 UTC



...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...

110821 0000 110821 1200 110822 0000 110822 1200



LAT LON LAT LON LAT LON LAT LON

BAMS 15.0N 59.0W 15.9N 62.1W 17.0N 65.0W 18.1N 67.9W

BAMD 15.0N 59.0W 15.7N 62.3W 16.5N 65.0W 17.1N 67.4W

BAMM 15.0N 59.0W 15.8N 62.0W 16.9N 64.7W 17.9N 67.3W

LBAR 15.0N 59.0W 15.8N 62.5W 16.7N 65.9W 17.2N 69.1W

SHIP 45KTS 55KTS 68KTS 80KTS

DSHP 45KTS 55KTS 68KTS 80KTS



...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...

110823 0000 110824 0000 110825 0000 110826 0000



LAT LON LAT LON LAT LON LAT LON

BAMS 19.3N 70.7W 21.0N 76.1W 21.5N 80.3W 22.5N 82.1W

BAMD 17.8N 69.6W 19.5N 72.6W 22.4N 75.6W 27.4N 78.9W

BAMM 19.0N 69.8W 20.7N 74.3W 22.1N 78.4W 24.2N 81.1W

LBAR 17.6N 72.0W 18.8N 77.1W 20.9N 80.2W 24.7N 81.3W

SHIP 92KTS 103KTS 106KTS 108KTS

DSHP 92KTS 80KTS 59KTS 61KTS



...INITIAL CONDITIONS...

LATCUR = 15.0N LONCUR = 59.0W DIRCUR = 280DEG SPDCUR = 19KT

LATM12 = 14.3N LONM12 = 54.9W DIRM12 = 277DEG SPDM12 = 21KT

LATM24 = 14.0N LONM24 = 51.2W

WNDCUR = 45KT RMAXWD = 60NM WNDM12 = 40KT

CENPRS = 1006MB OUTPRS = 1010MB OUTRAD = 175NM SDEPTH = M

RD34NE = 105NM RD34SE = 0NM RD34SW = 0NM RD34NW = 45NM



$$

NNNN
Member Since: July 15, 2006 Posts: 170 Comments: 53517
Some models still insist that Irene will get into the gulf.I that happens then WATCH OUT. Those sst and TCHP are high.That's if upper level conditions preveil.
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Why does the NHC base their track off the TVCN?
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Quoting Levi32:


Even if I wanted to I couldn't, as I have a flight home in 2 hours. I'll have an update tomorrow morning.


I know a nice girl in Cold Bay
Member Since: August 13, 2007 Posts: 0 Comments: 10480
Quoting Levi32:


Even if I wanted to I couldn't, as I have a flight home in 2 hours. I'll have an update tomorrow morning.


Have a safe flight.
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La Agencia para el Manejo de Emergecias ofrece conferencia de prensa veala en vivo:

Puerto Rico Emergency Managment press conference live Link
Member Since: July 14, 2008 Posts: 0 Comments: 248
Dr. Master, no spiral bands?????????????????way wut? Did you saw the satellite image?
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SHIPS brings it up to 90 knots before Hispaniola.

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Quoting TampaSpin:



Invest 97L appears nearly closed also.

umm, Tampa, it's not 97L anymore.
Member Since: November 13, 2009 Posts: 2 Comments: 728
Quoting MiamiHurricanes09:
A northward shift wasn't just quite the correct working on my part...more like a shift towards the right.



I'm going to wait and see if they do another update, looking at the raw data it appears HWFI and GFDI were not included in the TVCN.
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Just food for a thought as NAO will be neutral as we approach the peak of hurricane season.

Link

Member Since: May 9, 2007 Posts: 0 Comments: 154
Member Since: September 2, 2007 Posts: 178 Comments: 20439
Quoting MiamiHurricanes09:
A northward shift wasn't just quite the correct working on my part...more like a shift towards the right.




well...this gives more questions than answers...
Member Since: August 13, 2007 Posts: 0 Comments: 10480
Quoting Patrap:




Down the Rabbit Hole we all go..

Thats Low,,and Big

And On the prowl




Shhhhhh

I'd rather do like Scarlet and just think about it tomorrow.
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Quoting Levi32:


132 hours is just off Cape Canaveral.


is this an east coast storm now?
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Quoting KennyNebraska:


Answer. Political satire that fell flat.


oh (duh me)
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Vorticity shows Harvey has better vorticity than Irene, but Irene is a newborn.
Member Since: November 13, 2009 Posts: 2 Comments: 728
Quoting KennyNebraska:
Levi. Are you going to provide a new show for us to see tonight or do we wait for tomorrow?


Even if I wanted to I couldn't, as I have a flight home in 2 hours. I'll have an update tomorrow morning.
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Quoting JLPR2:
Well now, this image makes Irene look scary.
UUUUiiii, !! Yes it does, look scary. I called my sister and ask her if she know anything about Irene, she told me: "I don't know, but you broke with her last year. Didn't you? I just said bye,and hanged up. We weren't talking about the same Irene for sure... I guess people in the Island are unaware, since is "fin de semana",and all.
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Quoting Stormchaser2007:
00z TVCN has less Cuba and more water.

Also goes east of Florida.


... And hits where?!?!
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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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