#!/usr/bin/perl

use strict;
my ($file);

open(FILE, "<file.txt");
while(<FILE>) {
    chomp($_);
    if(/CITY/ ... /FLORIDA/) {
        if( ($file) = $_ =~ m/.+CITY:\s+(\w+)\s+/ ) {
           close(FH);
           $file .= '.txt';
           open(FH, ">>$file");
        }
        print FH "$_\n" unless $_ =~ m/FLORIDA/;
    }
}
close(FILE);