Need help with resume cover letter

I am usually good at writing things but for some reason I cannot start the first paragraph of my resume cover letter. Here is a bit of background. I am moving to Florida on January 14th and want to send out my resume to a bunch of law firms in Florida next week. We are going there from December 13-18, at which time I want to interview with some firms. I just dont know how to word my cover letter since I am not sending it in response to a posting or job advertisement. CAN SOMEONE PLEASEEEE help me!
THANKS!!!