Hurricane Irene Approaches the Bahamas
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
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Brevard county represents! :)
Yep, positive. Irene is not going to Miami.
The 2nd TROF (1st one just left) is coming down and will reinforce the weakness that pulls her NW/NNW and then N over the next two days... on Friday/Saturday, the 3rd TROF comes down into the Great Lakes, as stated by the NHC Discussion I posted.
Whether or not Irene continues to move NORTH instead of NNE/NE will be determined by how the TROF sets up at the Great Lakes... and the models won't have a good idea on that until Friday although they seem to favor a NNE motion as of now.
Bermuda? I think you musta skipped out on geography...
Has the GFS gone a bit west...wasn't that one of the more easterly models??
Maybe literally as well as figuratively.
Yes, the GFS has had a consistent easterly bias for a few days now.
yah isn't it nifty how NHS can just make their best line, call it gospel, then when it doesnt happen they back up and say...naaa we had it called all along, look at our huge cone of predict....we know better....now washington fund us.......lol
and if nothing else, shift the cone....how can we ever be wrong?
bureaucratic job security = why even think, try, or care?
So if you are going to fixate on the wobbles, thinking that this may mean that the storm is failing to follow the forecast track, don't forget to notice the wobbles that take place in any and all directions, not just one.
that is a pretty good sized windfield there...ummm, includes even SC...BLAH!!!
Good! At least a little interest in 90L, Yes it is looking healthy and moving west.
T-ville here as well... my 85 yo Mom is in Satellite Beach... If things change, I'll be makin speed to her place... for now its a 25% chance for low end TS force winds... but that was with a storm running up 77W... the wind feild (TS) is projected to be about 160NM to the NW/120 nm to the SW... each degree west of 77 moves the storm ~66 nm closer...
amazes me,....absolutely amazes me...
ALL wobbles do not have an equal and opposite wobble. Wobbles can be caused by many things and they may not be simple wobbles, but something more significant impacting the storm. Agreed, one cannot fixate simply on 1 wobble, but has to be looked at over time. In this case the last 2 or 3 satellite pics have shown a westward jog. Just have to see what happens next.
That actually holds true for each and every state that was and still is in the cone..not closing both eyes until she is due east of me and i am feeling no effects...
Bingo. I'm not going to delude myself or anyone else by saying we're going to get a direct hit, because that would just be stupid. But you're point is spot on, and it exactly why I'll be watching our girl until she's well out of our way. 50+mph winds are nothing to be willy nilly about, especially when I have a giant oak tree in my back yard waiting for a reason to come down.
hi my call sign is N1RG been a ham since 1957
dont orry about ur dad us hams can handle these type of situations,is he from pa. with the wb3 call sign??
tks rick
n1rg bay st. louis ms.he can look me up on the qrz database
THE UPPER RIDGE NUDGES CLOSER AND BELIEVE IT OR NOT... EVEN HOTTER TEMPERATURES ARE EXPECTED. A CONVERGENCE OF DRY AND SUBSIDENT AIR WILL LEAD TO INTENSE AFTERNOON HIGH TEMPERATURES ON FRIDAY AND AGAIN SATURDAY. THE NAM 12 2 METER TEMPS ARE PROGGED TO REACH 111 DEGREES ON FRIDAY AT CLL AND 109 AT HOUSTON.
Morphin into a monsta! I can see 125 in 2 PM, Irene pullin this out after all
That was the 11am update....
If I'm not mistaken wind-field is most important factor contributing to storm surge. Irene's going to be pushing quite a bit of water.
she has alredy begun her NW turn
if the upper level pattern had it where now the ridge was stronger above Irene with weak troughs not dipping down too far south, I could see your concern.
anyhow, with that said, still stay on guard but low chances of hitting e coast of florida directly
effects will be felt but not ones like the bahamas are feeling now, the carolinas will feel as well as the northeast
Its gonna head NW per models.
Lol. This is a joke right? Weak storms don't necessarily have to always go west. Also the little islands are nothing to a Hurricane. She will just plow through them especially with no mountains.
Weak storms are influenced moreso by lower level winds as opposed to stronger storms being influenced by higher level winds, so weaker storms due tend to go more westerly. Not saying they ALL do or will, but overall speaking........
Excact same point here.
lol thinking the same thing
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