Dr. Jeff Masters' WunderBlog

Category 3 Hurricane Irene tracks northwest through the Bahamas
Posted by: Dr. Jeff Masters, 20:55 GMT le 24 août 2011 +35
Hurricane Irene remains a powerful category 3 this afternoon, with maximum sustained winds of 120 mph. Irene is moving northwest through the Bahamas at 12 mph, and its center has cleared the northern edge of Crooked Island. The next islands in the path of Irene are Rum Cay (population 80) and Cat Island (population 1700), which it will encounter later tonight. Irene will track northeast of Long Island (in the Bahamas) over the next 24 hours. George Town has been reporting wind gusts up to around 40 mph this afternoon, and wind speed will likely increase during the next 12 hours as Irene's center passes about 30-40 miles to their northeast. Long Island in the Bahamas will likely see category 1 winds, which begin at 74 mph. Shelters on New Providence and Grand Bahama are open and ready for business, and Grand Bahama International Airport will remain closed until Irene passes.

Irene continues to look well-organized on satellite, especially compared to yesterday afternoon. Since then, intense upward motion, and therefore strong thunderstorm activity, has encompassed the center on all sides, which has led to a well-defined eye. Throughout the morning, Irene's eye wall has shrunk, and a new eye wall could be developing, although it remains unclear at this point. If this is the case, it could lead to some temporary weakening of the hurricane, which would be good for the Bahamas. This afternoon, Irene's hurricane-force winds extend 50 miles from the center, and tropical storm-force winds extend up to 205 miles from the center. Earlier this morning, an Air Force Hurricane Hunter mission investigated Irene and a NOAA Gulfstream (Gonzo) is currently collecting data around the hurricane.


Figure 1. Microwave satellite imagery of Irene captured at 8am this morning. Image source: Naval Research Laboratory.

Track forecast for Irene
NOAA has continued dropsonde missions today, scouring the atmosphere for data as far north as the waters off of South Carolina. Every bit of upper-air data that the models can ingest will lead to better forecasts and decreased uncertainty. These missions are an investment that pay off. Irene will track through the central Bahamas today, the northwestern Bahamas on Thursday, and approach the Outer Banks of North Carolina on Friday. Beyond this there is a bit of divergence in the models. Both the GFDL and the HWRF are forecasting a landfall on Long Island, New York, and the ECMWF continues to suggest a landfall even further west than that. NOGAPS is still the eastern outlier, which misses the U.S. all together and makes landfall in Canada. Today the official track forecast from the National Hurricane Center agrees with the GFS forecast through Saturday morning, and then diverges ever so slightly to the west of that through Monday. It has become clear over the past 3 days that everyone on the East Coast from North Carolina to Maine should be prepared to feel impacts from Hurricane Irene.


Figure 2. Official track forecast provided by the National Hurricane Center.

Intensity forecast for Irene
Irene continues to be embedded in a large envelope of moisture, and wind shear is expected to remain low to moderate, 5 - 20 knots, for the next three days. With water temperatures very warm, 28 - 30°C, these conditions should allow for intensification to a category 4 hurricane (winds of 131 to 155 mph). The only reliable model that's not forecasting this intensification is the GFS, and this is likely due to its relatively course spatial resolution. The National Hurricane Center expects Irene to intensify to a category 4 tomorrow, with a decrease in intensity back to a category 3 on Friday.

Links
For those of you wanting to know your odds of receiving hurricane force or tropical storm force winds, check out the NHC wind probability product.

Wunderground has detailed storm surge maps for the U.S. coast.

Our Wundermap is also a great resource for tracking hurricanes, with the ability to turn on multiple layers of data, including satellite, official track forecast, and current weather observations from not only the U.S. but the Caribbean and Bahamas, as well. Here's a link to get you started.

Angela
Categories: Hurricane
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3201. drg0dOwnCountry 08:18 GMT le 25 août 2011    

Member Since: 22 septembre 2005 Posts: 11 Comments: 1945
3202. atmosweather 08:18 GMT le 25 août 2011    
Quoting TomTaylor:
oh ouch, and I'm guessing you live on the east coast too?

I live on the west coast (Southern California specifically) so its not too late here


Just east of Orlando, FL. But in a couple of months I'll be moving just N of San Diego to start a new job with my father. Where abouts are you located?
Member Since: 24 septembre 2005 Posts: 33 Comments: 9255
3203. atmosweather 08:19 GMT le 25 août 2011    
Quoting Gorty:
I think the NHC will shift their track a little west for New England area for 5 am but the cone may very well stay the same.


I'd expect a small W-ward shift at days 4 and 5.
Member Since: 24 septembre 2005 Posts: 33 Comments: 9255
3204. TomTaylor 08:20 GMT le 25 août 2011    
Quoting atmosweather:


That would depend on the strength and exact tilt of the mid latitude trough. I'd say it's unlikely that it would amplify far enough to impart a W-erly component to the motion by days 4 and 5. However if the trough comes in more negatively tilted, similar to what the 00z GFS is hinting at, then she could move on a slightly NNW course through the NE US.
wait, help me out a sec, how would a trough induce a westerly component?

Do you mean like if the trough amplified or dug in enough to the west that the path of lowest pressures/least resistance would actually be slightly west of north causing Irene to move more westerly?
Member Since: 24 août 2010 Posts: 18 Comments: 3899
3205. Gorty 08:21 GMT le 25 août 2011    
Quoting atmosweather:


I'd expect a small W-ward shift at days 4 and 5.


Same. Idk why but I always like to say New England area rather than days 4 and 5 lol.
Member Since: 8 novembre 2008 Posts: 11 Comments: 1058
3206. RiverSteve 08:21 GMT le 25 août 2011    
new blog
Member Since: 14 août 2009 Posts: 0 Comments: 54
3207. atmosweather 08:22 GMT le 25 août 2011    
Quoting TomTaylor:
wait, help me out a sec, how would a trough induce a westerly component?

Do you mean like if the trough amplified or dug in enough to the west that the path of lowest pressures/least resistance would actually be slightly west of north causing Irene to move more westerly?


Yes, the Great Lakes trough could possibly deepen and amplify further to the south as the Euro and GFS are forecasting, and could even be at a slightly negative tilt which could force Irene a little to the NNW near the end of the 5 day period.
Member Since: 24 septembre 2005 Posts: 33 Comments: 9255
3208. TomTaylor 08:22 GMT le 25 août 2011    
Quoting drg0dOwnCountry:

Core still struggling. Been struggling just about all day. Irene actually looked nicest last night as far as organization is concerned.

Dvorak numbers also reflect that
Member Since: 24 août 2010 Posts: 18 Comments: 3899
3209. Vincent4989 08:23 GMT le 25 août 2011    
Poll:
What chances do you think NHC will downgrade Irene?
a.Never
b.Near 0 %
c.10%
d.20%
e.30%
f.40%
g.50%
h.60%
i.70%
j.80%
k.90%
l.Near 100%
m.Absolute 100%
Member Since: 13 novembre 2009 Posts: 2 Comments: 728
3210. Gorty 08:27 GMT le 25 août 2011    
Right now, then only thing that is really affecting her is herself with the inner stuff (LOL) I really don't know what to call it.

Could be sometime before she get's her inner stuff going again cause she's so large.
Member Since: 8 novembre 2008 Posts: 11 Comments: 1058
3211. njdevil 08:28 GMT le 25 août 2011    
The problem with saying "prepare" for the NY/NJ area is that most of the preparations are mental. "I need to do this, I need to go here.." etc.

Especially if the worst case of a clean shot somewhere at/around/east of NYC happens. You get what, 12-18 hours notice? Where people normally prepare for storms the storm is plodding along taking its time. Once this thing gets near NC, it's going to take off like a bat out of hell. And the storm will probably come in sometime around midday.

Doesn't give you much time to put your mental preparations into action... other than "RUN!"

This really could be a total mess. Don't like seeing models come in right over my head because I know how little time I'm going to get. Hell, the storms over the last couple of years that were doing runs closer to Bermuda made me nervous for the same reason, and that was irrational.
Member Since: 9 juillet 2008 Posts: 0 Comments: 145
3212. TomTaylor 08:29 GMT le 25 août 2011    
Quoting atmosweather:


Just east of Orlando, FL. But in a couple of months I'll be moving just N of San Diego to start a new job with my father. Where abouts are you located?
damn, so its 4am lol

And thats cool (not so cool if you enjoy weather...southern California is just about the capital of non-eventful/significant weather phenomenon. Little rain, little temp variation, persistent marine layer along the coast all year long, little thunderstorm activity, no snow (except in the mnts to the east), hail is a rarity, no tropical storms, etc, etc) I live in San Diego right now. More specifically, I live in University City, which is like a subsection/neighborhood in San Diego. It's just east of La Jolla and north of Clairemont.
Member Since: 24 août 2010 Posts: 18 Comments: 3899
3213. OracleDeAtlantis 09:15 GMT le 25 août 2011    
The models are trending west for good reason.

Irene is trending west ...



Member Since: 27 août 2009 Posts: 0 Comments: 290
3214. ncstorm 10:19 GMT le 25 août 2011    
I wake up and Wilmington is under a tropical storm watch now..
Member Since: 19 août 2006 Posts: 7 Comments: 8459
3215. CaneHunter031472 10:26 GMT le 25 août 2011    
Member Since: 1 août 2007 Posts: 0 Comments: 895
3216. Jtownboy 10:31 GMT le 25 août 2011    
Can someone post the 5:00 am update plz.
Member Since: 22 août 2011 Posts: 0 Comments: 30
3217. naviguesser 11:31 GMT le 25 août 2011    
Quoting vince1:

^Not conspiratorial and even if it reeks of politics, truth is more important than blissful ignorance.


I suspect that as poor as the government has been rated lately, they want to get something right. They look back on the Bush Admin response to Katrina as a major black-eye for him and this has the potential to be MUCH bigger.
Member Since: 15 septembre 2006 Posts: 0 Comments: 66
3218. midgulfmom 15:33 GMT le 25 août 2011    
Good Morning. To everyone in the cone: You are invited to check out my blog. I saved Hurricane prep tips that were added before Hurricane Gustave. Some great suggestions by hurricane veterans that I have used myself and found to be helpful. To all you Veterans please feel free to add your best tips once again. Please take Hurricane Irene seriously, my prayers are with you...
Member Since: 9 juillet 2005 Posts: 2 Comments: 1002

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About JeffMasters
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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