The idea of a hurricane off of the US east coast with warnings for the Bahamas gets enough attention. The risk of an impact on our shores is a threat. The idea of landfall with a track similar to Isabel (2003) is scary. That is what the GFS model is suggesting. I want to point out that this is only one possibly solution, but it deserves attention. Especially since we have had a few model runs continuing to show this. Note the latest tropical spaghetti shown below plots do vary, but a cluster of more models leaning on the east coast. As of this post, Joaquin has 75 mph winds but was strengthening. The next National Hurricane Center Update may update there track as well.
With respect to Maryland, see this model slider for the progress and timing. This frame continues to adjust, but I would keep the window of Sunday through Tuesday open for impact. Not a guarantee as these storms can change at the last minute based slight changes in intensity and speed. But compare to the track of Isabel below and you will see why it is worth considering at this early juncture. Please note that I hope this is wrong! But I feel I must share the info.
If there is a hook northwest, landfall to the south of the Chesapeake Bay would be the worst case. Over the Chesapeake would be bad, but the surge would be with the storm, not the duration of drag since the Delmarva would block it. A storm passing north would be the best case for Maryland, but worst for DE, NJ, and NY like Irene or Sandy. Just something to keep in mind.
GFS Model Slider –>