From the NHC 11pm discussion. Wild:
Similar to the previous advisory, the environment ahead of Michael
is expected to remain conducive for additional strengthening until
landfall occurs due to SSTs of at least 85 deg F beneath the
hurricane, combined with decreasing vertical wind shear along with
the shear vector shifting from current west-northwesterly to a less
hostile southwesterly component, which will be more along Michael's
forecast track. As a result, Michael is now explicitly forecast to
become a category 4 hurricane before landfall occurs.