Chris_in_Tampa wrote:That 98 knot reading was a 10 second peak flight level wind. The 30 second sustained wind in that observation was only 93 knots. The next observation right after that had 30 second sustained winds of 94 knots, so over that 1 minute interval you saw sustained flight level winds averaged to be about 93.5 knots.
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Regarding that SFMR wind, remember it is a 10 second peak wind. The 30 second sustained surface winds that can be calculated using a method I have discussed previously would mean the winds were 73.8 knots (~ 84.8 mph). If you look at the decoded observation at the link above, you will see the very next observation indicated that the 30 second surface wind could be estimated at 74.0 knots (~ 85.1 mph). Avergaing the two together, which would represent a 1 minute interval from observations taken directly next to each other, indicate the advisory intensity of 75 knots (around 85 mph), 1 minute sustained, is correct.
The problem with your analysis is that you are averaging in the wrong direction. The "one-minute average" that represents the definition of sustained wind refers to allowing 1 minute of air to pass over an anemometer. When an aircraft does a storm penetration, they are flying perpendicular to the wind, so to take a 1-min average in this context represents a radial average that smooths out the actual wind at the RMW. What you really want is a 1-min average in the tangential direction, but the planes don't fly downwind in the eyewall.
Upshot of all this is that, all else being equal, NHC traditionally interprets the 10-s aircraft flight-level wind as being temporally equivalent to a 1-min anemometer measurment (adjusted for elevation, of course). In the case of the 98 kt aircraft wind, the standard adjustment of 80% from 850 mb would give 78 kt at the surface. The advisory intensity was set to 75 kt, but could have been set at 80 kt, and might be in post-analysis. Either 75 or 80 is consistent with the 98 kt flight-level wind.
slam on you Humberto!
