Well, I’ve address a couple of items already. I’ll pick up on the wind speed estimates from the damage survey. We did the survey on the ground unable to get to areas east of Winnie and High Island where the high wind speed likely occurred. At first glance, the damage did not look that impressive mainly for a couple of reasons. First, construction of buildings in these areas was very poor and anything well built had little if any damage. Homes that did have damage were poorly built. There were quite a few trees uprooted, but there was also quite a bit of rainfall in the area leading to saturated grounds. This would make it easier for trees to uproot. Unlike tornadoes, the duration of wind speed also has to be considered. Looking at the damage, we found several damage indicators that would support 100 mph winds based off the EF damage scale. These indicators would be mainly significant damage to roofs, trees uprooted, but also well built power poles that were snapped. Again, this would indicate winds near 100 mph. We went on the low end of the wind speed based on these indicators mainly because of the poor construction and saturated ground. We went low also because of the long duration of 20-30 minutes of near hurricane strength or lower winds. We went too low at first. We finally got some aerial pictures of the damage from the Galveston Co EM with damage we had not seen. These pictures helped support raising the estimated winds speeds from the damage from 60-70 G 80 mph to 70-80 G 90 mph. The duration of the winds and the poor construction played a big role in estimating the wind speeds from the damage, different from estimating the winds from tornado damage.
I have also been able to go back and look at the radar data. If you want to look for yourself, download the level 2 data from NCDC and pop it into GR Analyst 2. We just got done archiving the AWIPS data and we’ll look at that as well. But just looking at the level 2 data in GRAE2, when the storm made landfall there were Doppler velocities around 85kts inbound over a broad area of High Island in the north eye wall. This was around 0610Z. About 15 minutes later, there were Doppler velocities inbound at around 105kts, again just east and northeast of High Island. Granted at this time the radar beam is about 3Kft above the ground, but this supports the hurricane aircraft reports of 98kts. So, is an 85 mph maximum sustained winds too much? Personally, I think it is very much in the ball park and a good estimate based on what data was available at the time. There is virtually nothing between High Island and Beaumont, so no way of knowing for sure.
I don’t think NHC over doing wind speeds is that much of an issue especially when you have good radar data (eye of storm was about 50nm from the HGX radar) and good aircraft measurements. Plus, you have to realize these products are not just for the public. Emergency management and FEMA use them also. Just about every emergency manager I know wants to know the worst case scenario, and what is the worst that can be expected. So if over doing wind speeds some to help out the emergency management plan rescue efforts and get needed supplies in place after the event, then I think that is well worth it. So, yes I agree we need to scrutinize the data and get the science right, but when it comes to the forecast and getting information out that can save lives, I think we can all live with a little overestimation of wind speeds especially when you have quality data to use despite a poor surface observation network. Further inland, again, this may be where the data needs to be re-evaluated and learned from. But, I still believe in making the best forecast you can with the data you have available and using situational awareness as needed to adjust. I think we also need to go back and look at the data to make sure we understand the science so we can make better forecasts next time. Post mortems are important in that aspect. I’m sure we as well as NHC will be looking at this case to learn as much as possible.
Sorry for the long post, but I finally got my thoughts together on this after a few days.
