I read this in the "how to" vortex message:
An eye diameter that shrinks (compared to the previous vortex message) may signal strengthening: just as a twirling ice skater spins faster as she pulls in her arms, a hurricane may "spin" faster as its eye gets smaller. Eye diameters are usually 10-20 nautical miles, while we sometimes see them as small as 5 nm to as large as 60 nm.

http://www.hurricanehunters.com/vortex.htm
Also in the lates Vortex message it stated that max winds were at 82kts so that would be just shy of a cat 2 storm