Look for it to be declared an F5. I cannot understand why it was given an F4 instead.
It seemed to vary a lot in intensity. At some points, it looked very similar to the May 3rd tornado. It may have reached F-5 at certain points. Unfortunately, the damage seems worse, because a lot of new buildings have went up in Moore since 1999.
It is much easier to reevaluate upward than downward, so the initial estimate will be low if there is any doubt. Just imagine trying to convince the media that it was only an EF4 after an initial estimate of EF5.
I looked through the documents which detail what level of damage match each EF level (a real snoozefest) and it was very detailed about how to analyze damage and what types of destruction match what level and how to do statistical analysis on the damage so that one freak collapsing building won't bias the estimate. The EF level is based on the damage (and therefore indirectly wind speed), not the width or the length of time on the ground so you can have a very small, short lived EF5 tornado or a large, long lasting but weak EF1 tornado. This one was big, long lasting and strong, but the first two don't control the EF level.