Hurricane Irene Approaches the Bahamas

By: Dr. Jeff Masters , 7:42 AM GMT on August 24, 2011

Share this Blog
11
+

As of 2AM EDT, Hurricane Irene was located at 21.3N, 72.6W, 400 miles southeast of Nassau. It was moving west-northwest at 9 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 966 mb. Hurricane warnings have been issued for all of the Bahamas and the Turks and Caicos Islands. Tropical storm warnings are in effect for Haiti from Le Mole St. Nicholas to the Dominican Republic border.

Satellite Views
Figure 1 shows that Irene has a large eye visible in infrared imagery, (26 miles across accoring to a report from the Hurricane Hunters at 130AM) with well-defined outflow cirrus bands. Tuesday evening, TRMM, NASA's tropical research satellite, flew directly overhead Irene, getting a radar scan of the storm using it's downward pointing radar, shown in Figure 2. It is immediately apparent that Irene has well-developed bands of rain showers, with strong storms present in the eyewall.


Figure 1 IR satellite view of Irene taken at 113AM EDT, August 23, 2011


Figure 2 TRMM radar overpass of Irene at 713PM EDT, August 22, 2011. Image courtesy of the Naval Research Laboratory

Track Forecast

Irene is forecast to move to the northwest, passing over all of the Bahamas by Thursday evening, then curving to the north. Irene then makes landfall in the US near or at the Outer Banks Saturday afternoon, then traveling along the mid-Atlantic coastline of the US. After Saturday, Irene may pose a threat to Long Island and the New England coastline. However, NHC is quick to remind us that the average forecast error for day 4 is 200 miles, so don't stop your hurricane preparations if you aren't in the immediate area of landfall. It is also important to note that the windfield of Irene is expected to be large, affecting areas distant from the immediate track of Irene's center. Tropical storm forces winds are expected to be found out to at least 150 miles away from Irene's center on Friday afternoon.

NHC is forecasting for Irene to become a major hurricane (winds faster than 110 mph), within 24 hours.


Figure 3 Official track forecast of Irene at 2AM EDT.

Forecast models and adaptive observations
The different forecast models are in fairly good agreement about Irene's track through the Bahamas and along the east coast of the US. The GFDL, a dynamical hurricane forecasting model, which had been a western outlier from the other models is now agreeing with them. When a set of weather models using slighly different initial views of the atmosphere and slightly different ways of simulating how the atmosphere works all agree on a forecast, then meteorlogists tend to believe that the forecast is more likely to occur. The 00Z GFS and ECMWF (wind swath shown in Figure 4) forecasts are nearly identical, which furthur boosts forecaster confidence.

In the 11PM forecast discussion, the NHC forecaster praises the NOAA Gulfstream IV (aka Gonzo) for providing infomation about the atmosphere around Irene that will influence it's track. Looking at the plan of the day valid for today, it will be a busy day for airborne reconnaissance. Three flights for the Air Force hurricane hunters, two flights for the Gulfstream IV, and two flights for NOAA 42, a WP-3D (aka Kermit).


Figure 4 Plot of the maximum sustained winds in mph over the next week from the 00Z ECMWF forecast.

Impacts

In the immediate future, Irene will have a significant impact on the Bahamas and surrounding islands. Hurricane force winds are ongoing over the Turks and Caicos islands and southeastern Bahamas. These locations can expect storm surges that are 5-8 feet above tide levels. The northwestern Bahamas can expect hurricane force winds Thursday, and storm surges that are 7-11 feet above tide levels. The Turks and Caicos islands and all of the Bahamas can expect 6-12 inches of rain over the next two days.

I still think people living along the east coast of the US should closely monitor Irene and review their hurricane preparations. Irene will be a large storm, impacting areas far from the storm center track.

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: 428 - 378

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 | 28 | 29Blog Index

Member Since: Posts: Comments:
426. GoWVU
Quoting wxobsvps:


Still a squeeze going on


Is it supposed to ease anytime soon? If not the entire SE could be hurting
Member Since: Posts: Comments:
I'm really worried about all the bays in Rhode Island and Mass.
Member Since: Posts: Comments:
ATCF 1200z update:

AL, 09, 2011082412, , BEST, 0, 219N, 733W, 100, 957, HU, 64, NEQ, 45, 40, 25, 40, 1008, 275, 15, 0, 0, L, 0, , 0, 0, IRENE, D,
Member Since: Posts: Comments:
Peak (10s) Flt. Lvl. Wind: 112 knots (~ 128.8 mph)
Member Since: Posts: Comments:
Quoting cat5hurricane:

Beautiful. This is what I've been looking for. I'm at a different PC and don't have my flash drive with me with all my bookmark links.

Thank you!


From that link, it looks like a real nice stadium effect is developing. I think this storm will be a Cat 4 before the next update.
Member Since: Posts: Comments:
Wow RI in place, Irene has become such a beautiful storm overnight...
Member Since: Posts: Comments:
Quoting TropicalAnalystwx13:


That is not true in this situation. The pattern is very complex, and now that Irene is a major, she can make her own environment.


Not good.is it true that once a stormspressure falls low enough, (say maybe 940mb)it can alter the atmosphere around it and nothing major influences it?
Member Since: Posts: Comments:
09L/MH/I/C3
RI FLAG (ON)
MARK
22.90n/73.13w





ALWAYS FOLLOW NHC/TPC FORECASTS FOR ALL WARNINGS REGARDING THIS STORM
Member Since: Posts: Comments:
NYC may be nothing like New Orleans, but both the Big Apple and the Big Easy have a lot of infrastructure at or below sea level. A significant storm surge (or even just a lot of rain) could quickly flood underground utility and transportation assets.

And drive an absolute army of rats to the surface…
Member Since: Posts: Comments:
416. HCW

Member Since: August 10, 2002 Posts: 0 Comments: 1406
Quoting wxobsvps:


she has come off her 295 heading to now 300...so it's a start.


^^^
Member Since: Posts: Comments:
Wow overnight has pumped the tropics up so much...
Irene Category 3 now, and 90L approaching code red, Cape verde system too...
Member Since: Posts: Comments:
Can Hurricanes Trigger Earthquakes?
http://www.wired.com/wiredscience/2011/01/can-hur ricanes-trigger-earthquakes/

A hurricane could affect aftershocks or trigger slow earthquakes and landslides already prone from erosion. There was a 4.2 earthquake in Puerto Rico before Irene past
Member Since: Posts: Comments:
700mb 2,801m (9,190 ft) 13.6°C (56.5°F) 11.5°C (52.7°F) 125° (from the SE) 113 knots (130 mph)

130 mph. My God. We pretty much have a Cat 4 on our hands.
Member Since: August 18, 2011 Posts: 0 Comments: 994
410. Jax82
We might have a 'Situation' on the Jersey Shore this weekend ;)
Member Since: Posts: Comments:
Quoting nrtiwlnvragn:
Rapid Scan visible loop


As real time as its going to get.
Member Since: Posts: Comments:
Quoting ironbanks:
I have flown into JFK many times. On approach you can see many low lying communities on the coast. I don't want to even think about the traffic jam an evacuation there would cause. Hope this storm stays way off the coast.


The entire south shore of long island is flat and low lying. I grew up there and have lots of friends and family still there including my sister. The last time they got a storm was Gloria back in the 80's and I think it was only an 80mph Cat 1 and I remember it taking out tons of trees. One came through a second story window in our house.
Member Since: Posts: Comments:
Last year at this time, the count was 4-2-0. It's currently 9-1-1.

Last year's Danielle didn't become a major hurricane until August 27, so we're slightly ahead time-wise.

At this time on August 24th last year, seasonal ACE stood at 12.0825; we're currently at 20.665 (and it'll climb rapidly for the next several days).
Member Since: Posts: Comments:
Rapid Scan visible loop
Member Since: Posts: Comments:
404. Vero1
Quoting LakeShadow:
Hey all! It's been a while! Thought I'd pop in and way hey for the first U.S. landfalling cane in a few years. I remember on The Weather Channel the It Could Happen Tomorrow series. The right angle of the coast of NYC can funnel in the storm surge to create significant flooding.... Anyone remember that episode? Think it could really happen?

History Channel Mega Disaster.

Can been viewed at: http://www.history.com/shows/mega-disasters
Member Since: Posts: Comments:
Hmmm the NOAA plane found a second wind maximum while going out of the NW eyewall...
Member Since: Posts: Comments:
Quoting WatchingThisOne:


They must have been watching the National Hurricane Channel :)


Irene is a category 3.
Member Since: Posts: Comments:
Good morning. I know all eyes are on Irene but did anyone happen to notice that 90L is up to 50% chance for development ?
Member Since: Posts: Comments:
936mb 95° (from the E) 121 knots (139 mph)
Member Since: Posts: Comments:
Quoting CBJeff:


I wasn't thinking date, I was thinking "call for help".
Ahhh, Got ya!! Like I said no offense intended.
Member Since: Posts: Comments:
A dropsound revealed winds as high as 121 knts in the eyewall... not at the surface but you have to have that high of winds above the surface before they develop at the surface... should only take 6-12 hours to mix those winds down to the surface ... I say Cat 4 by the 5 PM advisory if not earlier
Member Since: Posts: Comments:
Irene needs to make her NW turn soon huh?
Member Since: Posts: Comments:
394. 900MB
At this point it looks like Irene will survive to be a Cat 2 off the Jersey and Long Island coasts on Sunday...Where it hits exactly, still anyone's guess.
Member Since: Posts: Comments:
...IRENE BECOMES A CATEGORY THREE HURRICANE....EYE HEADED FOR THE
CROOKED AND ACKLINS ISLANDS...


SUMMARY OF 800 AM EDT...1200 UTC...INFORMATION
----------------------------------------------
LOCATION...21.9N 73.3W
ABOUT 55 MI...85 KM SE OF ACKLINS ISLAND BAHAMAS
ABOUT 335 MI...540 KM SE OF NASSAU
MAXIMUM SUSTAINED WINDS...115 MPH...185 KM/H
PRESENT MOVEMENT...WNW OR 300 DEGREES AT 9 MPH...15 KM/H
MINIMUM CENTRAL PRESSURE...957 MB...28.26 INCHES
Member Since: August 18, 2011 Posts: 0 Comments: 994
Quoting msgambler:
CBJeff, To be honest it would be a alot more meaningful it was to be on 9-11-11. But it isn't. No offense intended. I'm just trying to oint out that 9-1-11 isn't an important date in history (off the top of my head anyway).


I wasn't thinking date, I was thinking "call for help".
Member Since: Posts: Comments:
Hey all! It's been a while! Thought I'd pop in and way hey for the first U.S. landfalling cane in a few years. I remember on The Weather Channel the It Could Happen Tomorrow series. The right angle of the coast of NYC can funnel in the storm surge to create significant flooding.... Anyone remember that episode? Think it could really happen?
Member Since: Posts: Comments:
I have flown into JFK many times. On approach you can see many low lying communities on the coast. I don't want to even think about the traffic jam an evacuation there would cause. Hope this storm stays way off the coast.
Member Since: Posts: Comments:
Member Since: August 1, 2007 Posts: 0 Comments: 167
06Z GFDL and HWRF GFDL is shown as GHM on that site.
Member Since: Posts: Comments:
Quoting EastTexJake:
The Weather Channel just announced Cat 3 as of 8 am.


They must have been watching the National Hurricane Channel :)
Member Since: Posts: Comments:
Quoting Grandpato4:
Good morning. The folks are here putting up my hurricane shutters. I think I will delay my evacuation until tomorrow though because Irene just keeps shifting to the east.


PLEASE LEAVE TODAY. Tomorrow you will be on the road with hundreds of others evacuating, bumper to bumper traffic, tempers flaring, etc. The closer it gets to the arrival of the storm in your area, the worse the evacuation will be because so many people think..I just stay ONE MORE DAY..leave tomorrow. I have been caught in that miserable traffic. You don't want to do it.

Leave early. If you don't have friends or family to go to and will need a hotel/motel, the longer you wait, the harder it will be to find lodging. Not to mention trying to get gasoline. Stations will be selling out very fast and RAISING PRICES.

Again, just my experience and opinion on this matter.

Please stay safe. My prayers are with you, your family, your friends, and all folks along the path of this storm.
Member Since: Posts: Comments:
Good grief, that's busy airspace.
Member Since: Posts: Comments:
Quoting wxobsvps:
With the intensity comes more chance of a CONUS recurve.

That is good news, with no offense or disregard meant for our friends throughout the Bahamas.


That is not true in this situation. The pattern is very complex, and now that Irene is a major, she can make her own environment.
Member Since: Posts: Comments:
Quoting Bobbyweather:

You probably know but the NHC sitis faster than TWC


Yeah, but I've got the TV on while I read the blog, and it happened between breaks in commercials.
Member Since: Posts: Comments:
381. HCW
Member Since: August 10, 2002 Posts: 0 Comments: 1406
Member Since: May 27, 2009 Posts: 0 Comments: 4436
000
URNT12 KNHC 241203
VORTEX DATA MESSAGE AL092011
A. 24/11:46:10Z
B. 21 deg 58 min N
073 deg 19 min W
C. 700 mb 2717 m
D. NA
E. NA
F. 126 deg 112 kt
G. 039 deg 14 nm
H. 957 mb
I. 10 C / 3035 m
J. 17 C / 3050 m

K. NA / NA
L. CLOSED
M. C22
N. 12345 / 7
O. 0.02 / 2 nm
P. AF303 1409A IRENE OB 05
MAX FL WIND 110 KT NE QUAD 11:42:10Z
Member Since: Posts: Comments:
Anyone using the intellicast interactive map? I just found it while searching for caribbean radar and it has a alot of cool features. Overlaying the model tracks on the of the satellite really shows how precise the models are with this storm.
Member Since: Posts: Comments:

Viewing: 428 - 378

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 | 28 | 29Blog 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.