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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Here comes the nudger that yanks Irene North.....its a pretty flat trough tho........need some latitude to come pretty soon.
Yeah....But it's still early.
The evolution of that ULL (which is keeping he weakness open) could allow Irene to stay far off the US coast or bring it closer to the US coast.
We also have to keep in mind that 98L is assisting on weakening some the southern periphery of the Bermuda/Azores high so the bush being currently imposed onto Irene might be temporary as 98L gets closer to Irene and a more Northerly component to the track starts materializing by then.
927 that far north...
someone better turn the bs flag on!
HWRF should lay off the fry up, obviously causing indigestion.
Only time you'll see 930mb that high up is with a windstorm around Greenland, Iceland and the North Sea.
About 60 miles NNE
I only get up this early for Fishing... It has to be light out for Golf.
i agree with you but as seen in recent images the ULL is trying to bring irene farther west but the gap i still open for the nw turn. this will be very close. 98L will be a key player to how much the southern periphery of the high weakens but 98L looks to be fizziling so we will have to see what comes out of that
Indeed... very close gap.
Hope everyone has completed their preparations in Exuma, still a lot to be done here in Nassau.
This is the Hydrometeorological Prediction Center's 5 Day Quantitative Precipitation Forecast
Link
There are your major hurricane force winds.
I wonder if the NHC 8am discussion will mention it..the new player in the game
127kt?
Wow next advisory 130 mph then.
(~ 20.59 inHg) 2,840 meters
(~ 9,318 feet) - - From 127° at 109 knots
(From the SE at ~ 125.3 mph) 9.4°C*
(~ 48.9°F*) -* 112 knots
(~ 128.8 mph) -
Flight level, but oh dear god.
the 127 you see above is the wind direction and the 109 is sustained flight level winds.... the 112 is the flight level winds
That's the key... If the ULL is able to deteriorate the eastern flank of the C CONUS high and allow any incoming TROF to dig further W then more of the US E coast line could be in trouble, but if the ULL weakens and/or washes out then it would allow the C CONUS to build back to the E and keep the weakness in the SE coast which would imply a further offshore track on Irene's path.
Of course variables are not restricted to the above and there are some other factors, but in the short term the above should be a pretty good driving force.
A lot of interference with that reading. Questionable.
That said, it is probably a major by now.
Those are flight level winds from 700 mb (10,000 feet). Take off 15-20% and you get 90-95 kts at the surface.
Believe it or not, ECMWF is in the same general area, GFS at ~960mb.
Edit Add: 06Z GFDL is in that area also
HOUR:114.0 LONG: -74.61 LAT: 40.07 MIN PRESS (hPa): 931.51 MAX SURF WIND (KNOTS): 77.20
History Channel Mega Disaster.
Can been viewed at: http://www.history.com/shows/mega-disasters
The pressure doesn't really add up much with the winds. You can get it, but only usually after a EWRC or perhaps a landfall, but the pressure catches up quick.
Not sure why they're making it so low.
I noticed that ULL to of SC last night. And you're right! Sometimes they can "Pull" a system a little bit towards them.
Yeah, The last thing you want is to wait too late and get stuck in traffic. During Rita here in Houston the North bound Interstates were gridlocked for over 24hrs. with thousands of cars stuck without water and food, some running out of fuel. We did better during Ike, but if Rita hadn't turned North it would have been REALLY bad.
Anyway, beat the traffic, don't wait too long.
The NHC site updates quicker than the decoder that most people use lol.
956.0 mb
(~ 28.23 inHg)
Click to enlarge
Ok gotcha.
Anyways it's almost 5 am here in Victoria, so I better get some sleep, night all.
Since the pressure readings are off I like to use the geopotential height as a guide, and its gonna end up being around 2690 meters which is a full 100 meters lower than the 1AM center fix.
000
WTNT34 KNHC 241157
TCPAT4
BULLETIN
HURRICANE IRENE INTERMEDIATE ADVISORY NUMBER 16A
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092011
800 AM EDT WED AUG 24 2011
...IRENE BECOMES A CATEGORY THREE HURRICANE....EYE HEADED FOR THE
CROOKED AND ACKLINS ISLANDS...
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