Clark and the other METS can probably elaborate on this more.
During most heavy precipitation events. There is a tendancy for the winds above the boundary layer to take on a near vertical element, due to the heavy rain. Something similar to a downburst.

During Hurricane Katrina, Mobile NWS recorded wind velocities of 127-132mph at 1359Z on Aug 29th. Just prior to Katrina's landfall near Waveland,MS.
While the official Max Sustained Wind speed in the 1300Z Advisory was 135mph.
Yet the HRD plates indicate the Max 1 minute surface wind is at, or just under Hurricane Force of 75mph.

http://www.srh.noaa.gov/mob/0805Katrina/
http://www.srh.noaa.gov/mob/cgi-bin/imageview.php?dir=/0805Katrina&file=vel_2_mob_1359Z.GIF
http://www.nhc.noaa.gov/archive/2005/pub/al122005.public_b.026.shtml?
http://www.aoml.noaa.gov/hrd/Storm_pages/katrina2005/wind.html
ftp://ftp.aoml.noaa.gov/pub/hrd/hwind/2005/al12.2005/0829/1330/col02deg.png

I'm going to move this to the Ask/ Tell forum. As we have the possibility of Tropical Development~danielw