Well, I believe I guessed pretty accurately about the latest pressure fall in Dennis. The first vortex message had just been transmitted from recon:

URNT12 KNHC 081215
VORTEX DATA MESSAGE
A. 08/11:59:00Z
B. 20 deg 55 min N
079 deg 32 min W
C. NA mb 2587 m
D. 70 kt
E. 126 deg 037 nm
F. 187 deg 136 kt
G. 100 deg 008 nm
H. 938 mb
I. 9 C/ 3054 m
J. 20 C/ 3051 m
K. 10 C/ NA
L. CLOSED WALL
M. C16
N. 12345/07
O. 0.02 / 1 nm
P. AF308 0804A DENNIS OB 06
MAX FL WIND 136 KT E QUAD 11:56:40 Z
WIND SHIFT AT SURFACE ABOUT 1MIN PRIOR TO FLT LVL FIX

That equates to a central pressure of 27.70 with surface winds around 140 mph! This storm is deepening fairly rapidly.

--Lou