HD=[HsW;DirW].'; % combine data for convenience
Pattern=[HD(1:2,:)]; % the looked for pattern
[~,l2]=ismember(HD,Pattern,'rows'); % locations where pattern was found
N=sum(l2((l2==1)+1)==2); % count locations of L1 followed by L2
Above doesn't account for (assumed rare) possibility that the pattern line 1 may be the last element in the array. If that case were to occur, augment the l2 vector with a NaN or any nonmatching value to avoid the bounds error from the +1 address expression.
The locations of the match are simply
find(l2((l2==1)+1)==2)
It's often simpler to turn into strings for pattern matching as then one can make simply a byte comparison of vector or array of characters
