Dangerous Tropical Storm Irene headed for the Dominican Republic

By: Dr. Jeff Masters , 2:38 PM GMT on August 21, 2011

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Tropical Storm Irene roared into life last night, transitioning from a tropical wave to a 50 mph tropical storm in just a few short hours. Irene is getting organized quickly, and has the potential to become a hurricane by Monday morning. All interests in the Dominican Republic, Haiti, Cuba, the Bahamas, and South Florida should prepare for the arrival of this dangerous storm. An Air Force hurricane hunter aircraft in the storm found the strongest winds near 18°N latitude to the north of Irene's center at 8am this morning. After passing through the center, the plane returned to the area of strongest winds two hours later, and found that flight level winds at 5,000 feet had increased by about 5 - 8 mph. However, the pressure in the latest center fix taken at 10am EDT remained the same as two hours previously, 1007 mb, and the plane noted that Irene's center was not circular, signs that the storm still has some work to do before serious intensification can begin. Visible satellite loops and radar out of Martinique show the storm has rapidly organized this morning, with well-developed spiral bands forming and a large area of intense thunderstorms to the north of the center. Irene has shrugged off the dry air that was bothering it yesterday, and wind shear has fallen to the low range, 5 - 10 knots, as analyzed by the University of Wisconsin CIMSS group. Torrential rains and strong gusty winds are affecting the northern Lesser Antilles this morning. A wind gust of 41 mph was recorded at St. Eustatius at 8am local time.


Figure 1. Morning satellite image of Irene.

Track forecast for Irene
The computer models are in agreement that Irene will pass just south of Puerto Rico tonight, then hit the south coast of Hispaniola in the Dominican Republic or Haiti on Monday afternoon. Irene should then emerge into the channel between Haiti and Cuba on Tuesday afternoon, when the storm will have 12 or so hours over water before having to contend with Cuba. A trough of low pressure is expected to move across the Eastern U.S. on Wednesday and Thursday, turning Irene to the northwest and north by Thursday. The 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. Irene's strength will also matter--a stronger Irene is more likely to turn northward earlier. The most likely path for Irene is a track just east of the Florida Peninsula and into Georgia, South Carolina, or North Carolina by next weekend, but a landfall near Miami then directly up the Florida Peninsula is also a reasonable solution--like Tropical Storm Fay of 2008 did. 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.

Intensity forecast for Irene
Irene is embedded in a large envelope of moisture now, and wind shear will remain low, 5 - 10 knots, for the next five days. With water temperatures very warm, 28 - 30°C, these conditions should allow for intensification except when land is interfering. Irene's current appearance on satellite loops gives me the impression of a storm that is not fooling around, and I expect Irene will be a hurricane before hitting Hispaniola on Monday. Passage over Hispaniola will not destroy Irene, since it is a fairly large storm. Once the storm finishes with Hispaniola, it will have to deal with Cuba, which will keep Irene from intensifying significantly. Once Irene pops off the coast of Cuba Wednesday or Thursday into the Florida Straits, Irene will likely be a tropical storm. If the storm then has at least a day over water before hitting land, it will likely become a hurricane again, and could become a major hurricane if it ends up missing South Florida and moving over the warm waters on either side of the Florida Peninsula.

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 southern Mexico, but dissipation is expected tonight 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.

Invest 98L northwest of the Cape Verde Islands
A tropical wave few hundred miles northwest of the Cape Verde Islands off the coast of Africa, Invest 98L, has become disorganized and lost most of its heavy thunderstorms. The disturbance is moving over colder waters and encountering drier air, and NHC is giving 98L only a 10% chance of developing into a tropical depression by Tuesday. The latest set of model runs keep 98L well out to sea away from any land areas over the next five days.

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Long-range radar out of Puerto Rico

Jeff Masters

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3523. ronmil
Quoting serialteg:


thank you compatriota


You are welcome. That was at my in-laws this afternoon... Right now dark an quiet here in Caguas (center-east). We expect to be right on the north side of the center in a couple hours...
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5 Days ago the GFS model had Irene much more south than it is right now, with a south Florida landfall on Friday. Looks like we may now be out of the woods with this in south Florida, being Irene is more north now. The high is not as strong as originally thought. It will probably begin the curve north, east of south Florida, most likely over the Bahamas. I was planning to get gas for the generators today, but being Irene's present position, I am going to wait.
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No Tropicalanalysts the RAIN RATE is too high for it to be at the surface which it was a surface wind gust, recon didnt denote it, cuase they miss it sometimes
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3520. JLPR2
Just got power back, have had some decent gusts in rain bands.

Power is probably going down again soon.
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Quoting TropicalAnalystwx13:


So? The 60 mph wind is likely reliable given its organization on satellite and reports from neighboring islands.
It could be. I'm not saying it's not 60 mph, just saying you can't always trust SFMR in those situations.
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18Z HWRF for August 24 06Z is in the exact same spot as 12Z.. Only difference is the 18Z is stronger by 5 mb. 967mb vs 962 mb.
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3517. Jax82
Its a wibble, its a wobble, Irene seems to be making an eyewall right over St Croix, at least thats what i think it looks like on the radar. She's a strengthening, and it would be not good if the north side scrapes the whole southern coast of PR.
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991 mb storm in NW PR, going WNW direction. Maybe missing DR but that's bad for SE USA.
Member Since: August 1, 2011 Posts: 28 Comments: 8027
Quoting stormpetrol:


south, in my opinion


I'm thinking south of PR also. However, it could just be the tightening of the CoC that gives the illusion of a WSW drift vs W. If she does past S of PR, I would have to give more weight to the GFDL solution.
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Quoting Patrap:


I like the way Patrap lets the data do the talking....
Member Since: October 26, 2003 Posts: 0 Comments: 363
17.5n90.9w, 17.6n91.9w have been re-evaluated&altered for TD.Harvey_6pmGMT_ATCF
17.5n90.7w, 17.9n92.0w, 18.4n93.3w are now the most recent positions
Starting 20August_6pmGMT and ending 21August_6pmGMT

The 4 eastern line-segments represent TropicalDepressionHarvey's path
and the westernmost double dots overlay on top of the straightline projection.

Using straightline projection of the travel-speed&heading derived from the ATCF coordinates spanning the 6hours between 12pmGMT then 6pmGMT :
TD.Harvey's travel-speed was 15.3mph(24.7k/h) on a heading of 292.1degrees(NNW)
TD.Harvey has entered the Gulf of Mexico near Cocohital,Tabasco(state)

Copy&paste isj, mdb, 17.0n88.3w-17.3n89.6w, 17.3n89.6w-17.5n90.7w, 17.5n90.7w-17.9n92.0w, 17.9n92.0w-18.4n93.3w, mtt, 17.9n92.0w-18.43n93.378w into the GreatCircleMapper for more info

The previous mapping (for 21August_12pmGMT)
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3510. nymore
Patrap can you post the radar or satellite image again please. LOL
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Quoting MississippiWx:


Hey, Kman.

It certainly reformed farther to the north under the mid-level center. It has been consolidating ever since then and is now the best organized yet.


Thanks for that. Yes, looking very impressive. The ridge to the N has strengthened this afternoon which should take this just south of PR IMO.

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Quoting Stormchaser2007:


Would have landed on the tarmac.

lol


LOL
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3507. Patrap
Zoomed into the Vortex

Member Since: July 3, 2005 Posts: 426 Comments: 128630
I want to see the winds in the Eastern and Southeastern portion.
Member Since: July 15, 2006 Posts: 17 Comments: 10282
have they been to the southeast side yet thats where Im expectin nice winds
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Looks to be pretty much dead on NHC forecast track...
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Looks like a hot tower just fired in the NE eyewall:

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3501. WxLogic
At least HWRF corrected itself later (12hours) to be now S of PR:

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deleted double posting
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Quoting USAFwxguy:


I don't know, I'm seeing more 270 true.


Yeah, and it was moving south of St. Croix too.......
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Quoting StormJunkie:
Why didn't they throw a dropsonde in the center??? lol ;)


Would have landed on the tarmac.

lol
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3497. Patrap
Member Since: July 3, 2005 Posts: 426 Comments: 128630
Quoting SouthDadeFish:
Heavy rain rate there though. Probably not reliable.


So? The 60 mph wind is likely reliable given its organization on satellite and reports from neighboring islands.
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Quoting Jax82:
rut row, is she gonna pass north, south, or right over PR? Looks like directly.



if she tracks the length of Puerto Rico, would that put a hold on organization for the short term or is she large enough that it wouldnt have much effect? Granted that it would only about four or five hours.
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Quoting NICycloneChaser:


It's because that gaping hole that you are seeing is not an eye, it's a dry air spot, and it is being mixed out, making it look like it's moving WSW. The circulation is moving W/WNW, and recon should prove that after the next pass.


I sure hope so. I don't know much about hurricanes but looking at the radar it looks like there is circulation around that dry air spot. Where is the COC?
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Quoting SouthDadeFish:
Heavy rain rate there though. Probably not reliable.


It's also not that unbelievable for there to be 60mph winds.
Member Since: July 15, 2006 Posts: 17 Comments: 10282
993 mb 12 hr from now. Still south of PR.

Member Since: August 1, 2011 Posts: 28 Comments: 8027
Quoting TropicalAnalystwx13:
Recon so far supports an initial intensity of 50 knots (60 mph). Lets see if they find any stronger winds in the Northeastern Quadrant, which they will. I expect them to find 55 kt. wind speeds or stronger.
They are in the NE quadrant now lol
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Why didn't they throw a dropsonde in the center??? lol ;)
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""
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Quoting HurricaneDean07:
Contaminated 50 Knots, no 60 Mph yet...
Time: 22:47:00Z
Coordinates: 18.45N 64.1833W
Acft. Static Air Press: 843.2 mb (~ 24.90 inHg)
Acft. Geopotential Hgt: 1,537 meters (~ 5,043 feet)
Extrap. Sfc. Press: -
D-value: -
Flt. Lvl. Wind (30s): From 128° at 47 knots (From the SE at ~ 54.0 mph)
Air Temp: 13.0°C* (~ 55.4°F*)
Dew Pt: -*
Peak (10s) Flt. Lvl. Wind: 50 knots (~ 57.5 mph)
SFMR Peak (10s) Sfc. Wind: 51 knots (~ 58.6 mph)
SFMR Rain Rate: 30 mm/hr (~ 1.18 in/hr)

Time: 22:47:30Z
Coordinates: 18.45N 64.1667W
Acft. Static Air Press: 844.9 mb (~ 24.95 inHg)
Acft. Geopotential Hgt: 1,521 meters (~ 4,990 feet)
Extrap. Sfc. Press: -
D-value: -
Flt. Lvl. Wind (30s): From 126° at 46 knots (From the SE at ~ 52.9 mph)
Air Temp: 13.2°C* (~ 55.8°F*)
Dew Pt: -*
Peak (10s) Flt. Lvl. Wind: 48 knots (~ 55.2 mph)
SFMR Peak (10s) Sfc. Wind: 50 knots (~ 57.5 mph)
SFMR Rain Rate: 22 mm/hr (~ 0.87 in/hr)
(*) Denotes suspect data


It isn't contaminated....It shows the TEMPERATURE is contaminated.
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Quoting NCHurricane2009:


Did you see that eyeish feature tightening off southward on radar....there is no way this is suddenly wobbling southward...is there?


Lol...No. It's still basically on the same heading.
Member Since: July 15, 2006 Posts: 17 Comments: 10282
Quoting HurricaneSwirl:
51 knots
(~ 58.6 mph)

That's surface, btw.
Heavy rain rate there though. Probably not reliable.
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3481. Patrap
995mb looks like it was the bottom.
Member Since: July 3, 2005 Posts: 426 Comments: 128630
Recon so far supports an initial intensity of 50 knots (60 mph). Lets see if they find any stronger winds in the Northeastern Quadrant, which they will. I expect them to find 55 kt. wind speeds or stronger.
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um, 51 knots at surface. This makes Irene 60 mph tropical storm so far...
Member Since: August 1, 2011 Posts: 28 Comments: 8027
3451...Don't go there. Plus, that was a much faster moving system than this will be. Much faster!

Skye, this thing is going to meander slowly somewhere in the SE. Be it Fl, Ga, SC, or NC.
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Quoting OracleDeAtlantis:
More interesting for comparison than Fay, I think.





Thanks for the reminder for those of us in Charleston. We are well over due for one.
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Contaminated 50 Knots, no 60 Mph yet...
Time: 22:47:00Z
Coordinates: 18.45N 64.1833W
Acft. Static Air Press: 843.2 mb (~ 24.90 inHg)
Acft. Geopotential Hgt: 1,537 meters (~ 5,043 feet)
Extrap. Sfc. Press: -
D-value: -
Flt. Lvl. Wind (30s): From 128° at 47 knots (From the SE at ~ 54.0 mph)
Air Temp: 13.0°C* (~ 55.4°F*)
Dew Pt: -*
Peak (10s) Flt. Lvl. Wind: 50 knots (~ 57.5 mph)
SFMR Peak (10s) Sfc. Wind: 51 knots (~ 58.6 mph)
SFMR Rain Rate: 30 mm/hr (~ 1.18 in/hr)

Time: 22:47:30Z
Coordinates: 18.45N 64.1667W
Acft. Static Air Press: 844.9 mb (~ 24.95 inHg)
Acft. Geopotential Hgt: 1,521 meters (~ 4,990 feet)
Extrap. Sfc. Press: -
D-value: -
Flt. Lvl. Wind (30s): From 126° at 46 knots (From the SE at ~ 52.9 mph)
Air Temp: 13.2°C* (~ 55.8°F*)
Dew Pt: -*
Peak (10s) Flt. Lvl. Wind: 48 knots (~ 55.2 mph)
SFMR Peak (10s) Sfc. Wind: 50 knots (~ 57.5 mph)
SFMR Rain Rate: 22 mm/hr (~ 0.87 in/hr)
(*) Denotes suspect data
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Quoting WxLogic:
Well 18Z HWRF initialized ok, but 6HR into the run already has Irene NE of PR which clearly is not the case:



Throw it out clearly
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Quoting iamtheman99:

me like that quote, lol but really great quote it the truth


Who da cap fit, let dem wear it
Member Since: April 29, 2007 Posts: 0 Comments: 7928
3473. Levi32
51-kt surface wind from SFMR:


URNT15 KNHC 212249
AF302 0309A IRENE HDOB 05 20110821
223900 1816N 06432W 8459 01494 //// +140 //// 119051 055 045 010 01
223930 1817N 06431W 8428 01523 //// +140 //// 118047 048 045 010 05
224000 1818N 06430W 8439 01514 //// +143 //// 115053 054 044 005 01
224030 1818N 06429W 8427 01527 0058 +146 //// 117051 052 042 003 01
224100 1819N 06427W 8434 01520 0057 +153 //// 120051 051 041 003 01
224130 1820N 06426W 8432 01526 0060 +152 //// 122049 051 042 001 01
224200 1820N 06425W 8430 01529 0059 +157 +150 123050 050 040 002 00
224230 1821N 06423W 8438 01523 0060 +162 +143 124048 049 041 000 00
224300 1821N 06422W 8428 01537 0060 +165 +136 125047 048 040 001 00
224330 1822N 06421W 8435 01528 0060 +165 +141 127047 047 039 002 00
224400 1823N 06419W 8433 01533 0063 +160 +154 127046 047 039 001 00
224430 1823N 06418W 8434 01533 0065 +158 +157 128044 046 040 003 00
224500 1824N 06417W 8433 01535 0071 +151 //// 126045 047 040 005 01
224530 1825N 06415W 8430 01535 0066 +156 +156 129046 047 040 004 00
224600 1825N 06414W 8433 01535 0074 +148 //// 129048 051 040 008 01
224630 1826N 06413W 8439 01529 //// +131 //// 129047 048 047 019 01
224700 1827N 06411W 8432 01537 //// +130 //// 128047 050 051 030 01
224730 1827N 06410W 8449 01521 //// +132 //// 126046 048 050 022 01
224800 1828N 06408W 8425 01546 //// +145 //// 125042 045 041 009 01
224830 1828N 06407W 8433 01532 //// +143 //// 127036 042 042 017 05
Member Since: November 24, 2005 Posts: 635 Comments: 26652

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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.