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Ian’s estimated peak intensity of 140 kt and minimum central pressure of 937 mb at 1200 UTC 28 September are based on data from Air Force Reserve Unit and NOAA reconnaissance aircraft. During the missions, the maximum 10-second averaged flight-level winds reported in the hurricane’s core were 160 kt from a NOAA aircraft at 750 mb (an altitude of about 6800 ft) at 1013 UTC 28 September. These flight-level winds support a surface intensity estimate of 136 kt. There were also multiple peak SFMR surface wind estimates from both Air Force and NOAA aircraft of 137-138 kt at 1030 UTC and 1013 UTC, respectively. The SFMR data from the Air Force instrument was flagged as unreliable in the real-time products, but reprocessing in the post-storm analysis using an updated algorithm no longer flagged the peak values. Due to extreme turbulence in the region where the maximum sustained winds were located in the western quadrant, the aircraft was only able to sample that part of Ian’s core once. A profile of the winds from the NOAA P-3 Tail Doppler Radar showed a shallow maximum of winds largely below the aircraft altitude with speeds exceeding 160 kt 500-1000 ft (150-300 m) above the surface (Fig. 4). The combination of these data, and the consideration of potential undersampling from the SFMR3, support a peak intensity of 140 kt. It should be noted that the NHC best track intensities typically have an uncertainty of around ±10%, and that there is very little practical difference between a 140-kt category 5 and a 135-kt category 4 hurricane.
Ian’s estimated peak intensity of 140 kt and minimum central pressure of 937 mb at 1200 UTC 28 September are based on data from Air Force Reserve Unit and NOAA reconnaissance aircraft. During the missions, the maximum 10-second averaged flight-level winds reported in the hurricane’s core were 160 kt from a NOAA aircraft at 750 mb (an altitude of about 6800 ft) at 1013 UTC 28 September. These flight-level winds support a surface intensity estimate of 136 kt. There were also multiple peak SFMR surface wind estimates from both Air Force and NOAA aircraft of 137-138 kt at 1030 UTC and 1013 UTC, respectively. The SFMR data from the Air Force instrument was flagged as unreliable in the real-time products, but reprocessing in the post-storm analysis using an updated algorithm no longer flagged the peak values. Due to extreme turbulence in the region where the maximum sustained winds were located in the western quadrant, the aircraft was only able to sample that part of Ian’s core once. A profile of the winds from the NOAA P-3 Tail Doppler Radar showed a shallow maximum of winds largely below the aircraft altitude with speeds exceeding 160 kt 500-1000 ft (150-300 m) above the surface (Fig. 4). The combination of these data, and the consideration of potential undersampling from the SFMR3, support a peak intensity of 140 kt. It should be noted that the NHC best track intensities typically have an uncertainty of around ±10%, and that there is very little practical difference between a 140-kt category 5 and a 135-kt category 4 hurricane.
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