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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People, do not focus on center line of cone. Focus on whole cone. NHC did not rules out GOM just yet, so we still don't know where it's going.
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Quoting divdog:
If it follows that path it will get shredded pretty badly.BTW what surprises you about that path?

IRENE is large and moving fast. Land probably won't destroy it.
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Quoting Grandpato4:
I am watching this very closely.


Aren't you in both FL and NC? Then yea, you need to watch it closely.
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170. ackee
I would not be suprise if Irene MOVES over SW PR past north of hispanola
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Quoting KEEPEROFTHEGATE:
MODELS ARE OFF ON THE LEFT ITS TO THE RIGHT OF PR
I agree completely.
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looks like this is heading for NC
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Quoting presslord:


he's good...I'm goin' up with him in a little while....please send thoughts and prayers my way

I'm sure you'll be fine, Just don't barf. It can hold 2 people right.
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Quoting KEEPEROFTHEGATE:
MODELS ARE OFF ON THE LEFT ITS TO THE RIGHT OF PR
Weak elongated center. Do you not agree with the new track of NHC??

I still feel it stays south of PR and shaves the SW coast perhaps.
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165. A4Guy
I wonder why the NHC is choosing to keep the track a bit west of the TVCN consensus? Continuity, maybe, so they don't jump around so much, is my guess. Usually they explain the reasoning in the discussion...but this discussion seems pretty brief.
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Quoting WeatherNerdPR:
HURRICANE WARNING????!!!!!
I wonder if I'll have school tomorrow.


If it were here, we would not have school tomorrow. Considering the system is expected to pass just south, or make landfall, or/in Puerto Rico late tonight into early tomorrow morning, it would be wise to cancel, or at least delay, school.

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162. HCW
Quoting TropicalAnalystwx13:
The cone needs to be shifted to the right...


I expect it to be shifted to the left a little at 5pm :)
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Quoting FLdewey:
Interesting...



Not what I expected... but that's why I are no science guy.
If it follows that path it will get shredded pretty badly.BTW what surprises you about that path?
Member Since: August 22, 2008 Posts: 0 Comments: 755
Quoting FLdewey:


you should call them and tell them.


lol.
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Quoting TropicalAnalystwx13:
The cone needs to be shifted to the right...
It's right in line with the consensus model.

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Quoting AussieStorm:

Seek him press.
How is that dare devil boy of yours.


he's good...I'm goin' up with him in a little while....please send thoughts and prayers my way
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Quoting HCW:
If you need expected wind times for a certain location please let me know


They are holding the split Florida in two track.

Does anyone notice how much NW movement is shown towards the end of the cone on day 5.

hmmm
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HURRICANE WARNING????!!!!!
I wonder if I'll have school tomorrow.
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Quoting MiamiHurricanes09:
This system really isn't organized, lol.


You are right. Too much dry air. There is really no clear center on irene. Also, dry air and land interaction are going to keep her weak, which then makes the track forecast more problematic. This will be an interesting one to watch...
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MODELS ARE OFF ON THE LEFT ITS TO THE RIGHT OF PR
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Quoting ncstorm:
.INTENSIFICATION SEEMS LIKELY AND IRENE IS
FORECAST TO BECOME A HURRICANE BY THE TIME IT REACHES HISPANIOLA.

Haiti dont need this at all


Well...the only shining light I see for Haiti is that the center has a high chance of regenerating to the north some more...leading a path through PR and then just north of DR and Hispaniola all together so Haiti gets the much weaker south side of Irene....
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Quoting ElConando:
Not to be the P451 on the blog, but Irene seems somewhat ragged and its surface pressure has been rising since its inception. Maybe dry air will be a saving grace yet again.


I agree but it seems to be mixing out. also St Kitts measured a 1002 mb press and hour ago as the coc passed over them
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The cone needs to be shifted to the right...
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Quoting presslord:


were I not recently humbled...I'd be raisin' hell about this...
Hurricane Earl almost did it to us, but we haven't been slammed by a major storm since Isabel in 2003. Before that, it was Floyd.
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Quoting presslord:


were I not recently humbled...I'd be raisin' hell about this...

Seek him press.
How is that dare devil boy of yours.
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Currently what south Florida should expect is the same thing that was experienced back in 2005 when Katrina moved through southern Florida as a weak category 1. Things will change...as usual...however.

Oh damn, I just made a Katrina comparison. Sorry blog. I won't let that happen again.
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Quoting P451:


With the short bit of imagery I've looked at I think a PR landfall anywhere from the SE point to the central southern coast --- traverse the island - and emerge on the NE coastline of DR...exiting DR not to far afterwards -- and being free of land north of Haiti.

That would spell Major Hurricane for the Bahamas.


This, of course, is loosely based on some short imagery watching, and the connecting of the dots of the vortex messages.


Per 11 am discussion....

"...THE GFDL MODEL TAKES IRENE TO THE WEST
OF THE FLORIDA PENINSULA WHILE THE HWRF MODEL TAKES IT THROUGH THE
NORTHWESTERN BAHAMAS..."

scenario you propose track-wise is something like what the HWRF model shows track-wise....
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Cone remains virtually the same:



Small shift to the left on the later part.
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track moved west
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If the center Of Irene were to remain north of D.R. ,it definitely changes the intensity forecast and could be another mass evac situation for Florida,similar to Rita evac. situation in Texas. Not good!
Member Since: June 24, 2007 Posts: 0 Comments: 1457
139. 900MB
Quoting 900MB:
Thanks, Doc!

IMHO:
Irene is just one blow up from hurricane status and that could come at any time with very strong odds that it will happen in next 24 hours.

It would take a lot to keep Irene south of Puerto Rico at this point, and a hurricane warning should be posted.


Hurricane warning just posted for PR!
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Even if Irene is a bit higher, considering the terrain in the way, an Ernesto from 2006 wouldn't be too bad considering the doom 'n' gloom from the models recently with this system.

Still hoping the current tropical storm streak goes on.
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731

URNT12 KNHC 211426

VORTEX DATA MESSAGE AL092011

A. 21/14:00:00Z

B. 16 deg 55 min N

062 deg 48 min W

C. 850 mb 1472 m

D. 46 kt

E. 046 deg 42 nm

F. 123 deg 53 kt

G. 046 deg 80 nm

H. 1007 mb

I. 15 C / 1523 m

J. 17 C / 1524 m

K. NA / NA

L. NA

M. NA

N. 1345 / 08

O. 0.02 / 10 nm

P. AF300 0209A IRENE OB 08

MAX FL WIND 53 KT NE QUAD 13:34:30Z

20NM L/V CENTER ELONGATED NE TO SW

;
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Quoting MiamiHurricanes09:
Lol, you can tell they had to push that discussion out quickly.


lol.
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Quoting MahFL:
It's going to travel over a lot of hostile terrain....


That certainly seems to be the case...We have seen many a system destroyed by those mountains.
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134. HCW
If you need expected wind times for a certain location please let me know


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Quoting Bluestorm5:
not trying to spells doom for my own state (also lives in Carolinas), but it just possible if it shaves Florida. If it landfalls in Miami, it'll be slightly weaker when it comes to Carolinas. East Coast, it's time...


were I not recently humbled...I'd be raisin' hell about this...
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Quoting Neapolitan:
Lots to watch. And just think: it's only August 21. :-\


Yeah, because that makes everyone else feel soooo much better.

LOL.
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INTERESTS IN FLORIDA ARE ADVISED NOT TO FOCUS
ON THE EXACT FORECAST TRACK BECAUSE OF THE INHERENT UNCERTAINTIES
IN LONGER-RANGE FORECASTS.

LOL

They are telling us not to argue about where it is going....
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on bright side, it'll ends that d*** drought in Carolinas... Texas need to get rain even more than we do, though.
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Quoting P451:
North of 17N, north of the forecast points. This trend started last night and continues. You can't rule out a PR landfall with this setup.



If this continues she could come in on the southern coast of PR and exit the northern coast of DR and head north of Haiti - intensify - and target Florida as a major.

Note, I said COULD, I have not put much thought into it.

All you can do is look at imagery and that is what it is showing.

While steering currents would lead you to believe she should bend a little more westward with time that's not quite how they work or are to be interpreted. These aren't roads and the storm is not a car on a road.

990-999mb storm




970-989mb storm




A stronger system goes further north.
looks like due west on that loop,but hope she hits P.R. AND D.R and dies a slow death!
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Quoting BenBIogger:


I wasn't aware that they postpone the mission to tomorrow.


that's tonight at 8pm, I don't think they postponed it
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Lol, you can tell they had to push that discussion out quickly.
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Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 21st day of the month at 14:26Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 300)
Storm Number & Year: 09L in 2011
Storm Name: Irene (flight in the North Atlantic basin)
Mission Number: 2
Observation Number: 08
A. Time of Center Fix: 21st day of the month at 14:00:00Z
B. Center Fix Coordinates: 16°55'N 62°48'W (16.9167N 62.8W) (View map)
B. Center Fix Location: 27 miles (43 km) to the S (190°) from Basseterre, Saint Kitts and Nevis.
C. Minimum Height at Standard Level: 1,472m (4,829ft) at 850mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 46kts (~ 52.9mph)
E. Location of the Estimated Maximum Surface Wind: 42 nautical miles (48 statute miles) to the NE (46°) of center fix
F. Maximum Flight Level Wind Inbound: From 123° at 53kts (From the ESE at ~ 61.0mph)
G. Location of Maximum Flight Level Wind Inbound: 80 nautical miles (92 statute miles) to the NE (46°) of center fix
H. Minimum Sea Level Pressure: 1007mb (29.74 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 15°C (59°F) at a pressure alt. of 1,523m (4,997ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 17°C (63°F) at a pressure alt. of 1,524m (5,000ft)
K. Dewpoint Temp & Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Not Available
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Wind, Pressure and Temperature
N. Fix Levels (sfc and flt lvl centers are within 5nm of each other): Surface and 850mb
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 10 nautical miles
Remarks Section - Remarks That Were Decoded...
Maximum Flight Level Wind: 53kts (~ 61.0mph) in the northeast quadrant at 13:34:30Z
Remarks Section - Additional Remarks...
20NM L/V CENTER ELONGATED NE TO SW

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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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