Reports from the National Data Buoy Center's Stations in the During the Passage of Hurricane Gustav

25 August - 03 September 2008

This report provides a summary of some of the wind speed parameters, the sea-level pressure, and wave parameter reports from the National Data Buoy Center's (NDBC) stations in the vicinity of Hurricane Gustav's track.

Figure 1: NDBC Stations within 300NM of Hurricane Gustav's Track

Description of Measurements (also see: http://www.ndbc.noaa.gov/measdes.shtml)

Wind Speed: For stations in this report, wind speed is sampled at a rate of 1.0 Hz. For the Coastal-Marine Automated Network (C-MAN) station, PLSF1, wind speeds are reported to NDBC in knots to a resolution of 0.1 knots. C-MAN wind speeds have been converted to meters per second (m/s) for this report, where 1 m/s = 1.94 knots. For the buoy stations (42003, 42007, 42039, 42040, and 42059) wind speeds are reported to NDBC in meters per second to a resolution of 0.1 m/s. For the plot legends:

CWS: The average wind speed over a 10-minute period at the anemometer height. In this report, data are plotted at the time of the end of the valid 10-minute period.

MXGT1: The Peak 5-second gust during the past hour at the anemometer height. The time of MXGT1 is reported to the nearest minute, however, in this report data are plotted at the valid time of the hourly report.

WSPD1: The average wind speed for a period of 2 minutes for C-MAN stations and 8 minutes for buoy stations.

GUST1: The highest five-second average wind speed during the 2 or 8 minute sampling period.

Pressure: For stations in this report, pressure is sampled at a rate of 1.0 Hz and reported to a resolution of 0.1 hectoPascal (hPa). For the plot legends:

BARO1: Sea-level Pressure. Coastal-Marine Automated Network (C-MAN) stations average the pressure over 2 minutes. The buoy stations average the pressure over 8-minutes.

In addition 42059 (as well as 42056, 42057, and 42058) are equipped with Hurricane Supplemental Measurements:

Winds:

MX1MGT1: Maximum 1-minute wind speed during the previous hour.

Pressure:

MN1MSLP1: Lowest 1-minute sea-level pressure during the past hour when the sea-level pressure is less than 1008 hPa.

Wave:For buoys 42003, 42039, and 42056 the wave sampling period is 40 minutes and sampled at a rate of 1.7066 Hz. For buoys 42001 and 42007, the wave sampling period is 20 minutes at a sampling rate of 2.0 Hz.

WVHGT: The significant wave height that represents the average of the highest one-third of the waves during the wave sampling period and is computed from the zeroth spectral moment (m0) as 4 * v m0 .

DOMPD: The Dominant Period that represents the wave period (time from between consecutive passes of the wave crests) of the waves with the most energy.

Closest Point of Approach (CPA):Time, bearing (degrees True), and distance (Nautical Miles) from the station to Hurricane Gustav at CPA are computed using the positions from the National Hurricane Center's advisories that have been interpolated to hourly values for positions, wind speed (intensity), and central pressure.

Figure 2: Buoy 42059: Winds (Anemometer Height 10 m) and Sea-Level Pressure

42059 is equipped with Hurricane Supplemental Measurements - lowest 1-minute sea-level pressure and maximum 1-minute wind speed. The National Hurricane Center used winds from 42059 to set the initial intensity of then Tropical Depression 7:

ZCZC MIATCDAT2 ALL
TTAA00 KNHC DDHHMM
TROPICAL DEPRESSION SEVEN DISCUSSION NUMBER 1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072008
1100 AM EDT MON AUG 25 2008

…OUR INITIAL INTENSITY ESTIMATE IS CONSERVATIVELY SET AT 30 KT BASED ON AN EARLIER REPORT FROM NOAA DATA BUOY 42059.
…

Source: http://www.nhc.noaa.gov/archive/2008/al07/al072008.discus.001.shtml

Link to Station Page: http://www.ndbc.noaa.gov/station_page.php?station=42059

Figure 3: C-MAN Station Pulaski Shoal Light FL (PLSF1): Winds (Anemometer Height 17.7m) and Sea-Level Pressure

Link to Station Page: http://www.ndbc.noaa.gov/station_page.php?station=PLSF1

Figure 4: Buoy 42003 (42A03 is the identifier for the backup system) Eastern Gulf of Mexico: Winds (Anemometer Height 10.0m) and Sea-Level Pressure

42003/42A03 stopped transmitting after the 1600Z report on the 31st. Seas were 34 feet at the last report.

Figure 5: Buoy 42003 Significant Wave Height (WVHGT)

The 10.51-m significant wave height was the 2nd highest report for August for 42003 (for the period of record July1977- Aug 2008) slightly below the 10.57 meters reported during Hurricane Katrina in 2005 (in which 42003 capsized). The highest wave height for 42003 of 11.4 meters was recorded in 2004 during the passage of Hurricane Ivan. Five of the six highest wave heights have occurred since 2004 (three with Ivan) - 10.5 m was recorded in November 1985 associated with Hurricane Kate.

Link to Station Page: http://www.ndbc.noaa.gov/station_page.php?station=42003

Figure 6: Buoy 42039 (South of Pensacola FL) Winds (Anemometer Height 5.0 m) and Sea-Level Pressure

Figure 7: Buoy 42039 Significant Wave Height (WVHGT)

Link to Station Page: http://www.ndbc.noaa.gov/station_page.php?station=42039

Figure 8: Buoy 42040 (South of Mobile AL) Winds (Anemometer Height 5.0 m) and Sea-Level Pressure

42040 has reported the two highest wave heights in the Gulf of Mexico for Hurricanes Ivan (2004) and Katrina (2005). For Gustav, 42040 had only the second highest wave height of 10.3 m to 42003's 10.5 m before it ceased transmissions

Figure 9: Buoy 42040 Significant Wave Height (WVHGT)

Link to Station Page: http://www.ndbc.noaa.gov/station_page.php?station=42040

Figure 10: Buoy 42007 (South of Biloxi MS) Winds (Anemometer Height 5.0 m) and Sea-Level Pressure

Figure 11: Buoy 42007 Significant Wave Height (WVHGT)

Link to Station Page: http://www.ndbc.noaa.gov/station_page.php?station=42007