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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3123. MahFL
997 now.
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3122. WxLogic
@69HR:

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3120. Levi32
Quoting Stormchaser2007:
Not a good spot...

69 hours

18z GFS



A track over the Bahamas puts it over the warmest water possible, and then right up the Gulf Stream no matter where it makes landfall.
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Quoting Stormchaser2007:
Not a good spot...

69 hours

18z GFS



Watch this bomb as it moves for the Carolinas.
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Quoting wahooskipper:
Someone please tell the NWS in Tampa that "irregardless" isn't a word.


Was just about to post that. Use of that word is like fingernails on a chalkboard
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Hurricane Swirl... not many people are able to evacuate.
At least in Puerto Rico, people in most dangerous areas (flooding and storm surge) can go to schools which are used as shelters.
But evacuations per say, not feasible. Cant really airlift people out of the island or to safety when the whole island is to be affected.
Either way, keep in mind most our homes are concrete and can actually withstand these storms... so if you aren't in a flood prone area you can usually ride them out.
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Not a good spot...

69 hours

18z GFS

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TS.Irene's_6pmGMT_ATCF : Starting 20August_6pmGMT and ending 21August_6pmGMT

The 4 eastern line-segments represent TropicalStormIrene's path
and the westernmost line-segment is the straightline projection.

Using straightline projection of the travel-speed&heading derived from the ATCF coordinates spanning the 6hours between 12pmGMT then 6pmGMT :
TS.Irene's travel-speed was 16.5mph(26.6k/h) on a heading of 299.4degrees(NNW)
TS.Irene was headed toward passage over Culebra,PuertoRico ~3hours from now

Copy&paste puj, 14.6n57.0w-15.0n59.0w, 15.0n59.0w-16.0n60.4w, 16.0n60.4w-16.8n62.4w, 16.8n62.4w-17.5n63.7w, cpx, 16.8n62.4w-18.31n65.24w into the GreatCircleMapper for more info

The previous mapping (for 21August_12pmGMT)
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Quoting islander101010:
trees falling


yuppers
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3111. DVG
Quoting Levi32:


I meant no disrespect. Common sense just doesn't support the idea that a 5-day forecast track which is only a 90 mile shift from a state means that the state is safe.

I apologize if I sounded abrupt.


Don't let anyone pull a Storm Watch on you.

His loss is still felt. If you leave, this blog is pretty kaput.
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Quoting HurricaneSwirl:
Hey just a question.. Where do people in PR go to evacuate? Or even worse.. An even smaller island such as St Croix. Good thing this is only a TS/minimal Cat 1 so far.

We all stay in during a storm. People in lower elevations go to shelters, if they want to, unless the risk is so high they are forced to leave their homes and go to the shelter.
Member Since: July 7, 2010 Posts: 0 Comments: 5725
Quoting Levi32:
997.6mb and NW winds...center rolling just north of St. Croix, barely.



Then the central pressure should be 995-996 mb.
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3108. Patrap
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Quoting TropicalAnalystwx13:


No, Levi's explanation makes since. That would also explain why Irene continues to spit out outflow boundaries despite the rest of the system looks good.


It's a partial eye, but she is building an eyewall...
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3106. Levi32
Quoting HurricaneDean07:
Levi can you post a link for St croix...
Post 3088


Link
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3105. Dakster
Quoting ElConando:


Funny, I did the same. The microwave was about to tell where the storm will hit and then... the timer went off...


I know, so annoying... Just like I was wondering why that frisbee keeps getting bigger and then it hits me..

Make it back up to Tallahassee already?
Member Since: March 10, 2006 Posts: 0 Comments: 10646
Quoting ProgressivePulse:



Appreciate the thoughts, likewise. I am hoping they do as well, this is my daughters first week of school, VPK, and would be her first hurricane.


She is blessed to have a father who stays on top of the situation. I am sure she is getting lots of good information from you to help her understand what's happening. A lot of fear comes from a lack of knowledge...
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Quoting Stormchaser2007:
Starting to like it's new environment by 57

This is about 50 miles west of the last run with stronger ridging to the north. Let's watch what happens.
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Quoting TropicalAnalystwx13:


No, Levi's explanation makes since. That would also explain why Irene continues to spit out outflow boundaries despite the rest of the system looks good.




ok
Member Since: May 21, 2006 Posts: 5091 Comments: 115437
Levi can you post a link for St croix...
Post 3088
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Quoting RevHeather:
How far are the TS winds reaching out from the eye?


TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 150 MILES...240 KM
FROM THE CENTER.
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Quoting Gearsts:
Whats the number of that bouy?


I think it's a station on St. Croix, rather than a buoy, but it is CHSV3
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Just got in and haven't read back too much. Wondering if anyone here is reporting from St. Thomas? What are they getting? Expecting? Tried to call but call never goes through.

TIA
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Quoting presslord:
AM 970 News/Talk St. Croix...live Irene coverageLink
trees falling
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56 knot gust in St. Thomas
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Quoting Tazmanian:





trust me that is a full eye on the rader i re call seeing this with IKE that is no dry spot


No, Levi's explanation makes since. That would also explain why Irene continues to spit out outflow boundaries despite the rest of the system looks good.
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Quoting lucreto:
Weakening flag still on that means it's weakening folks.


Taking what CIMSS ADT says, or any CIMSS product for that matter, as the final word isn't the way to go.. Why are you so intent on downcasting Irene, anyway? Everything you're saying is false.
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3093. Dakster
Quoting CothranRoss:


Some microwavable pizza and popcorn?


Yeah... Gotta have food to watch this...
Member Since: March 10, 2006 Posts: 0 Comments: 10646
3092. Gearsts
Quoting lucreto:
Weakening flag still on that means it's weakening folks.
No that was on since morning.
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The "fine" tuning of the track will not occur until after Irene gets back over water North of Cuba/Hispanola but it looks pretty certain right now that the Bahamas will be first in line after that and they may be in in the NE Quad or Eyewall depending on the ultimate track....Also need to watch for possible passage over or very close to the Gulf Stream if it approaches the SE Florida coast.
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Quoting Dakster:


I looked at the Microwave at 4pm too. Took out some pizza and popcorn..


Funny, I did the same. The microwave was about to tell where the storm will hit and then... the timer went off...
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How far are the TS winds reaching out from the eye?
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3088. Levi32
997.6mb and NW winds...center rolling just north of St. Croix, barely.

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Quoting Drakoen:


It is microwave imagery of Irene. That graphic analyzes deep convection containing frozen hydrometeors, with low brightness shown in conjunction with an eyewall and the rainbands. We use this image to study the structure of the cyclone.



ok cool thanks
Member Since: May 21, 2006 Posts: 5091 Comments: 115437
Quoting MississippiWx:


Lol...You must be a rookie with tropical systems. :-)

Well, I only remember Jeanne, and this is similiar. And probably stronger by the time it gets here. I apparently went thru Georges, but I was WAY too young to remember.
On another note, winds picking up here.
Member Since: July 7, 2010 Posts: 0 Comments: 5725
Starting to like it's new environment by 57

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Poof factor now coming into play......not making a forecast, just saying a lot better looking storms than this haven't made it past Hispaniola.
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Quoting Levi32:


Look in the southeast part of the "eye". The center is tighter than the clear area, and it's still east of St. Croix if the wind is northerly there.


Spot on, it is clearly trying to tighten up in that SE quadrent of the "void". The report of N winds still coming out of St. Croix verifies this. They are reporting sub 999MB now and the center is still off shore. I suspect somewhere around 995MB by the time it reaches the island. JMO
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Quoting leftlink:



ok, now station CHSV3 at 5:24pm reported a reading of 29.48, which is 998.30mb



5:30 measurement is 29.46, or 997.62mb. Center not passed yet.
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I'll guess a 25% chance of a landfall in FL, 10% in GA, 50% in SC, and 10% in NC, with 5% either dying or out to sea.

What do you think Levi? Or you Drakoen?
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3080. Drakoen
Quoting Tazmanian:



what is that showing me


It is microwave imagery of Irene. That graphic analyzes deep convection containing frozen hydrometeors, with low brightness shown in conjunction with an eyewall and the rainbands. We use this image to study the structure of the cyclone.
Member Since: October 28, 2006 Posts: 57 Comments: 30727
3079. Gearsts
Quoting NICycloneChaser:


*Is going down pretty fast.
Whats the number of that bouy?
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Someone please tell the NWS in Tampa that "irregardless" isn't a word.
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3076. Skyepony (Mod)
Quoting HurricaneDean07:
Can someone post an image or a link for St croix Station...


Link
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Quoting Dakster:


I looked at the Microwave at 4pm too. Took out some pizza and popcorn..


Some microwavable pizza and popcorn?
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Hey just a question.. Where do people in PR go to evacuate? Or even worse.. An even smaller island such as St Croix. Good thing this is only a TS/minimal Cat 1 so far.
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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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