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NOAA Buoy Will Take Direct Hit From Dean

UPDATE 0156AM EDT Friday: The 2AM EDT Advisory was just released and Hurricane Hunter aircraft report increased average windspeed to 150mph and 930mb of central pressure.

As noted in the 11pm NHC Discussion, NOAA Buoy 42059 will take an almost direct hit from the eye of Hurricane Dean in the next couple of hours. This will give us a great look at the current state of Dean from sea-level.

Buoy 42059 is located at 15°00'20" N 67°29'44" W in the Caribbean Sea. The 2AM advisory placed Hurricane Dean at 15.0°N 66.7°W tracking west at 18mph. One degree is equal to 60 nautical miles so Dean is about 80 nm east of the Buoy. and should be there within a few hours.

Buoy 42059
NOAA Buoys generally update every hour and the 0550z (150AM EDT) update just came over the wire. Here are some key details: 38.9kt sustained winds gusting to 46.6kt, 26.9ft wave height with an average wave period (the amount of time between crests) of 9.3 seconds. Additionally, air pressure is dropping, down to 29.50" or 998mb. Water temperature is currently 83.8 degrees F.

Windspeed: Since 1950z yesterday, windspeed has steadily increased, jumping from (hour-by-hour) 17kt to 21.4kt, 23.3kt, 25.3kt, 27.2kt, and then a significant jump in the last 2 hours from 29.1kt to 36.9kt to 38.9kt. Windspeed is the average continuous windspeed over an eight minute period.

Pressure: Over the previous 8 hours, barometric pressure has fallen from 1009mb to 1002mb and then to 998mb over the past hour.

Waves: Over the same 7 hour period, wave heights increased hour-by-hour from 7.5ft, 8.2ft, 8.5ft, 9.5ft, 11.2ft, 13.1ft, 17.1ft, 20.3ft to 22.6ft an hour ago and 26.9ft currently. Interestingly, most of the earlier observations reported the waves to be "steep" but the past 4 observations have had "average" steepness. This is important because steepness of a wave is an indication of where it formed. The flatter the wave, the further away it was generated. For example, the tsunami wave of the Boxing Day storm in 2004 took several minutes from the water starting to rise before it peaked.

Additionally, the average period between waves has increased from 5 seconds between waves 8 hours ago to 8.3 seconds between waves. Distance between waves is also an indicator of the distance the wave has traveled, similar to the steepness. The longer the time between crests, the farther the wave has traveled.

Finally, here is a graph that shows the trending of windspeed and air pressure at Buoy 42059.

NOAA Buoy 42059 History

From the National Data Buoy Center, a description of Buoy 42059, a 6-meter NOMAD Buoy:

The 6-meter NOMAD is an aluminum-hulled, boat-shaped buoy which provides relatively high cost effectiveness and excellent long-term survivability in severe seas. These buoys are highly directional and have a quick rotational response. There have been no known capsizings of 6-meter NOMAD hulls. The relatively small size of the NOMAD allows for superb transportability via flatbed trailer, rail, or ship. Like the 3-meter discus, they are less likely to corrode and the magnetic effects on the compass are slight.

The 6-meter NOMAD Buoy

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