Category 2 Irene Approaches The Bahamas

By: Dr. Jeff Masters , 7:51 AM GMT on August 23, 2011

Share this Blog
19
+

As of 2am EDT, Hurricane Irene was located at 20.1N, 69.7W, 135 miles southeast of Grand Turk Island. It was moving west-northwest at 12 mph with maximum sustained winds of 100 mph, making it a Category 2 storm on the Saffir-Simpson scale. Irene has a minimum central pressure of 978 mb. Hurricane warnings have been issued for the northern coast of the Dominican Republic from the Haiti board to Cabo Engano, the southeastern and central Bahamas, and the Turks and Caicos islands. Hurricane watches have been posted for the north coast of Haiti from Le Mole, St. Nicholas to the Dominican border and the northwestern Bahamas. Tropical storm warnings are in effect for all of Haiti and the southern coast of the Dominican Republic from Cabo Engano to Santo Domingo.

5AM Update
As of 5am EDT, Hurricane Irene was located at 20.3N, 70.1W, 105 miles southeast of Grand Turk Island. It was moving west-northwest at 12 mph with maximum sustained winds of 100 mph, keeping it a Category 2 storm on the Saffir-Simpson scale. Irene has a minimum central pressure of 978 mb.

Figure 1 shows that Irene is maturing into a vigorous storm, with apparent waves in the western edge of the cirrus outflow.


Figure 1 IR satellite view of Irene taken at 135AM EDT, August 22, 2011

Track Forecast

Irene is forecast to move to the north-northwest, passing over all of the Bahama islands by Thursday evening, at which points it starts curving to the north. Irene is forecast to make landfall in the US near Wilmington, NC Saturday evening. However, it is important to note that this is not a definitive forecast, the average forecast error for day 5 is 250 miles. The timing of Irene's recurvature depends on how quickly several small troughs of low pressure in the Northeastern US move to the east. After Saturday, Irene may pose a threat to the mid-Atlantic coastline and locations further north, but it is too early to make a skillful forecast for those regions.

NHC is forecasting for Irene to become a major hurricane (winds faster than 110 mph), within 24 hours, then reaching peak intensity at 130 mph (Category 4 storm) by 8pm EDT Thursday evening.

Forecast models and adaptive observations
The different forecast models are in rough agreement until Irene nears the Carolinas. The dynamical hurricane forecasting models, GFDL and HWRF, have Irene making landfall near Charleston, SC. NGFDL (a variant of the GFDL that uses NOGAPS for background conditions) has landfall near Morehead City, NC, and the GFS has Irene crossing the Outer Banks. The UKMET forecast track splits the difference, placing Irene near Myrtle Beach, SC at landfall.

To reduce the model spread, and improve the track forecast error, the NOAA Gulfstream IV and an Air Force WC-130J have been flying dropsonde missions north of Irene. A dropsonde is an meteorological instrument package dropped from a plane that can tell you the vertical profile of temperature, pressure, moisture, and winds. By flying these missions, the dropsondes can improve all of the numerical weather prediction models initial picture of the atmospheres, which improves the forecast. Also, NHC has asked NWS offices in the southeastern US that launch weather balloons to do so every 6 hours instead of the normal 12 hour frequency.


Figure 2 Official track forecast of Irene as of 2am.

5AM update
The 00Z ECMWF forecast is available and Figure 3 shows the maximum wind speed over the next week for the eastern coast of the US. Green indicates tropical storm force winds, while yellow and orange are hurricane-force winds. The important thing is not to fixate on the predicted landfall location, but to see that Irene's winds will affect areas far away from landfall. The GFS, not shown, agrees with ECMWF that Irene will have a large area of tropical-storm force winds associated with it.

Figure 3 Maximum wind-speed in mph from the 00Z August 23 ECMWF forecast for the next week.

Impacts

In the immediate future, Irene is expected to have a significant impact on the Bahamas and surrounding islands. Hurricane force winds are forecast to reach the southeastern Bahamas and the Turks and Caicos sometime this afternoon or evening. These locations can also expect 5-10 inches of rain. Three to six inches of rain are forecast over northern Hispaniola, with isolated areas receiving up to 10 inches. This could lead to flash flooding and mudslides in mountaineous terrain. NHC is predicting a storm surge of 9-13 feet above normal tide level for the southeastern Bahamas and the Turks and Caicos.

Outside of the islands immediately impacted by Irene, it is my judgement that everybody living on the eastern coast of the US should monitor Irene and review their hurricane preparations over the next few days.

Dr. Masters will have a new blog entry this morning, and Angela Fritz will be covering the afternoon. I'll be back on third shift tonight.

Thanks for reading,

Dr. Rob Carver

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 1085 - 1035

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28Blog Index

Quoting SPLbeater:


LOL, i have a weather station. only thing that works is the pressure, but....wont help a darnt hing with irene, any smart person would know that:)

If the only thing that works is the pressure, then you don't have a weather station; you have a barometer... ;-)
Member Since: Posts: Comments:
Quoting CaneHunter031472:


As I previously explained, Hurricanes follow only one thing and it is the law of Physics. Their mission is to cool down the waters of the atlantic by removing the stored heat energy and move it to higher latitudes therefore they will always tend to move north because of Earth roational dynamics. Ridges stop them from doing this so when you see a hurricane moving west more than likely it is because to their norht there is a strong ridge steering them that way, but as soon as they find a weakness norht they go. This is the case here. The weakness is projected to be east of Florida way east of Florida may i say and that explain the track designated by the NHC. For it to do what you claim the ridge would need ot be west enough inside FL and the weaknes to be in the GOMEX. The trof would have to first be really weak and second pull out really fast for this to be possible. It does not seem to be the case this time, but It happened before.
I thought a hurricanes job was to remove excess latent heat out of the tropics...They are not there to cool the waters. ????
Member Since: Posts: Comments:
While I agree that Irene has been basically moving WNW, the last 24 hours imo would same like a more N of west motion, rather a true WNW movement, jmo. Just wait putting on the bulletproof vest :)
Member Since: Posts: Comments:
1081. 7544
west wobble again cone goes east
Member Since: Posts: Comments:
Irene moved a bit more west. I think this blog is going to be crazy now.
Member Since: Posts: Comments:
Quoting whepton3:
11A advisory out... not gonna post it... assuming by being here you have the internet.


LOL!!
Member Since: August 13, 2007 Posts: 0 Comments: 10492
Its official, florida is out of the da cone. No more west wobble casting...
Member Since: Posts: Comments:
For anyone who is NOT prepared or ready to evacuate in the cone. Hurricane Ike ('08) was "only" a Cat II storm, but had a large windfield like Irene.



Good luck and God bless anyone in the path of this one, and we are praying it curves straight back out into the Atlantic (and misses Bermuda!!!)
Member Since: Posts: Comments:
1074. Skyepony (Mod)
975.2mb
Member Since: Posts: Comments:
Wind field is growing pretty rapidly...
Member Since: December 18, 2006 Posts: 7 Comments: 2686
Anyone seen Reedzone lately?

I miss his 1000 mile wide cones and celebrations for "nailing" the forecast.
Member Since: Posts: Comments:
i'm thinking she is going to stay on this same pattern till she gets just to around 78 then lets see what she decides to do..if she stays on this same course it would put her between lower bahamas and cuba...plenty of warm water to deal with...but thats just me..
Member Since: Posts: Comments:
1070. Patrap


Member Since: Posts: Comments:
Quoting Patrap:
Storm Relative 1km Geostationary Visible Imagery


Here we go with "we got an eye now" comments...
Member Since: Posts: Comments:
Quoting NICycloneChaser:


Didn't you hear the news? The Bahamas were just taken over by the fish population of the Atlantic.


Are those the folks from Atlantis, the Atlantans?
Member Since: Posts: Comments:
11A advisory out... not gonna post it... assuming by being here you have the internet.
Member Since: Posts: Comments:
1066. DocBen
Cape Cod anyone? New England would have a very interesting time if they took a direct hit. Of course, it looks like they will get a lot of TS wind/rain anyway.

Years ago when I lived in Boston I would sit on the rocks on the north shore during nor'easters. definitely makes a person feel small in the face of nature.
Member Since: Posts: Comments:
Don't look for anything to come towards Texas for awhile, it has been 105 to 107 here all month and now they are saying this weekend thru next week it will be hotter because the High Pressure will get stronger? Maybe after next week the Heatwave will break? Right now the Gulf is protected big time.
Member Since: Posts: Comments:
HURRICANE CENTER LOCATED NEAR 20.5N 71.0W AT 23/1500Z
POSITION ACCURATE WITHIN 20 NM

PRESENT MOVEMENT TOWARD THE WEST-NORTHWEST OR 295 DEGREES AT 10 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 980 MB
MAX SUSTAINED WINDS 85 KT WITH GUSTS TO 105 KT.
64 KT....... 45NE 30SE 20SW 35NW.
50 KT....... 90NE 60SE 60SW 70NW.
34 KT.......180NE 120SE 120SW 130NW.
12 FT SEAS..240NE 120SE 60SW 180NW.
Member Since: Posts: Comments:
1062. brianc
Quoting Orcasystems:
Time: 14:38:30Z
Coordinates: 20.5167N 70.9667W
Acft. Static Air Press: 691.6 mb (~ 20.42 inHg)
Acft. Geopotential Hgt: 3,010 meters (~ 9,875 feet)
Extrap. Sfc. Press: 976.4 mb (~ 28.83 inHg)
D-value: -





Port of track just a smidge


I see that, also. Thanks for all you do, Orca!
Member Since: Posts: Comments:
1061. Patrap
Storm Relative 1km Geostationary Visible Imagery


Member Since: Posts: Comments:
Quoting quakeman55:

Nah, he gets all of his "data" from his weather station located in his mother's basement.


LOL, i have a weather station. only thing that works is the pressure, but....wont help a darnt hing with irene, any smart person would know that:)
Member Since: Posts: Comments:
Quoting NSgirl:
Good morning folks, my name is Connie, I live in Nova Scotia, Canada......wondering what's the likelyhood we'll get some effects from Irene up here????


I wouldn't be playing on the rocks at Peggy's cove when it goes past just yet :)
Member Since: Posts: Comments:
Quoting surferjoe5899:


Actually, Katrina hit Miami-Dade as a Cat1 hurricane
Didn't they expect it to wane over land but the everglades kept it steady as she goes? That impressed me...
Member Since: Posts: Comments:
Quoting HCW:
90L model runs look a little wacky


,the spread shown w the bam models indicate wind sheer should keep it from developing for a few days imo
Member Since: Posts: Comments:
Quoting Patrap:
Enhanced Infrared (IR) Imagery (4 km Mercator)




Hispaniola is disrupting inflow.
Member Since: Posts: Comments:
Looks more and more like Florida won't see much... maybe an errant rotating thunderstorm or two.

Beach erosion will be extensive.

Those Bahamians are a tough crowd... they're dealt with worse. :-)
Member Since: Posts: Comments:
Quoting Bluestorm5:
yea, I posted that before Google Earth recon updated it.


I know, the turn suprised me too lol.
Member Since: Posts: Comments:
LiLi!!!
Member Since: Posts: Comments:
Time: 14:38:30Z
Coordinates: 20.5167N 70.9667W
Acft. Static Air Press: 691.6 mb (~ 20.42 inHg)
Acft. Geopotential Hgt: 3,010 meters (~ 9,875 feet)
Extrap. Sfc. Press: 976.4 mb (~ 28.83 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 326 at 4 knots (From the NW/NNW at ~ 4.6 mph)
Air Temp: 14.0C (~ 57.2F)
Dew Pt: 10.0C (~ 50.0F)
Peak (10s) Flt. Lvl. Wind: 8 knots (~ 9.2 mph)
SFMR Peak (10s) Sfc. Wind: 23 knots* (~ 26.4 mph*)
SFMR Rain Rate: 1 mm/hr* (~ 0.04 in/hr*)
(*) Denotes suspect data

center fix i think
Member Since: Posts: Comments:
1051. NSgirl
Good morning folks, my name is Connie, I live in Nova Scotia, Canada......wondering what's the likelyhood we'll get some effects from Irene up here????
Member Since: Posts: Comments:
Quoting wolftribe2009:
I swear the nest person to call IRENE a FISH STORM is going to have a bucket of crow thrown at you by ME! This ISN"T a Fish Storm because she already hit the isalnds in the eastern Caribbean and the Bahamas also are in serious trouble. All this talk of Florida and the Carolinas but no one is talking about Irene's first date partners in the Bahamas.

CAT 3-4 in the Bahamas=Disaster also=NO FISH STORM


Didn't you hear the news? The Bahamas were just taken over by the fish population of the Atlantic.
Member Since: Posts: Comments:
This shift in the models to the east is also in result to a stronger storm early in its cycle. If Irene continues to ingest dry air and not able to complete a complete CDO this could have impacts on future model runs shifting slight back west and east with each flucuation in intensity.

Though the trough and Bermuda High correlation is also impacting her track, I still believe that her current intensity from here over the next 24-48 hrs could impact how far west she may go.

We also have a blob sittin over the Gulf Stream just may make things even more interesting, although she will likley absorb it and thats even if it is still there, which I highly doubt it will, but until her eye becomes completely developed within this storm she is going to jog west and north and back and forth until she develops it.

Member Since: Posts: Comments:
Quoting NJ2S:
On a serious note....what can NYC expect from Irene? And what's the time frame? If she moves up coast will she pick up speed...?


I'm also in Northern NJ.

If the current thinking pans out and Irene skirts right up along the coast, probably something similar to Floyd. If the track shifts to the left or right, that could change.
Member Since: Posts: Comments:
Quoting NICycloneChaser:


Recon turned towards southwest as they came into the centre. Peak flight-level winds of 67 knots in south eastern eyewall.
yea, I posted that before Google Earth recon updated it.
Member Since: Posts: Comments:
Quoting cloudburst2011:



HEY I RESENT BEING CALLED AND IDIOT IM WELL AWARE OF IRENE HITTING THE BAHAMA ISLANDS I CANT DO A THING ABOUT THAT...I WAS CONCERNED ABOUT THE CAROLINAS AND I SEE THE TROF DIGGING DEEP DOWN THE EAST COAST AND A 70% CHANCE OF IRENE GOING OUT TO SEA...IM SORRY IF YOU CANT SEE THAT BUT ITS GREAT NEWS FOR THE CAROLINAS AND IF I WERE U I WOULD CHILL ..YOU MUST LIVE IN THE CAROLINAS TO HAVE AND ATTITUDE LIKE YOU JUST DISPLAYED...YOU NEED TO ACCEPT IT I BEEN DOING THIS FOR OVER 20 YEARS AND IRENE IF SHE DOESNT STALL IS GOING TO GO OUT TO SEA...IM SORRY FOR THOSE IN THE BAHAMAS BUT I CANT DO NOTHING ABOUT THAT BUT SAY SOME PRAYERS FOR THEM..


there is one thing you CAN do about it... never ever ever ever ever call this storm a fish storm again
Member Since: Posts: Comments:
Quoting AllStar17:
Pressure continuing to fall with Irene.


The extrapolated pressure readings have been consistently 2 or 3 mb lower than what the dropsonde finds over the last day, so minimum pressure is likely still around 978, possibly as high as 980.
Member Since: Posts: Comments:
Aren't we due to have someone say she's missing the turn? Florida / Gulf / New Orleans / Cozumel better get ready? Happens with every one of these turns.

If these models and thus the projected path continue to move east, the Rapid Blog Dissipation Flag = ON.

Be safe out there in the Bahamas!!
Member Since: Posts: Comments:
Quoting wolftribe2009:
I swear the nest person to call IRENE a FISH STORM is going to have a bucket of crow thrown at you by ME! This ISN"T a Fish Storm because she already hit the isalnds in the eastern Caribbean and the Bahamas also are in serious trouble. All this talk of Florida and the Carolinas but no one is talking about Irene's first date partners in the Bahamas.

CAT 3-4 in the Bahamas=Disaster also=NO FISH STORM


++++ a whole bunch. Some of the people on here forget there are other people in the world other then themselves.
Member Since: Posts: Comments:
1041. WxLogic
Based on the possible center fix... Irene is not moving as fast as it was though (as expected - weak steering, land interaction, SAT obs, etc...) so from what I tell it will be short of the next forecast point.

The next couple HH center fixes would let us know where is moving in the assumption an eye doesn't fully develop first.
Member Since: Posts: Comments:
1038. Patrap
Enhanced Infrared (IR) Imagery (4 km Mercator)


Member Since: Posts: Comments:
Pressure continuing to fall with Irene.
Member Since: Posts: Comments:
Quoting cloudburst2011:




I WILL SAY IT EVEN IF IRENE WERE TO TO STALL FLORIDA IS COMPLETELY OUT THE WOODS...IT WOULD EFFECT THE CAROLINAS IF THAT WAS TO HAPPEN BUT IRENE SHOWS NO SIGNS OF STALLING IN FACE THE STEERING CURRENTS HAVE BECOME MORE STABLE IN THE LAST 12 HOURS...



Not quite true, If Irene stalls, she could miss the trof and get caught under the ridge forcing her to move in a more westerly fashion. But she's not stalled at all. Also a stalling system could mean that it found the corner of the ridge and that it is starting to shift to a more northward trajectory.
Member Since: August 1, 2007 Posts: 0 Comments: 193

Viewing: 1085 - 1035

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

Local Weather

Overcast
55 °F
Overcast