This is a pretty easy problem.
Using the file:for-each-line to iterate over each line, I increment a variable for each increase. I also leave the most recently read value on the stack for the next comparison.
The variable is initialized to -1. My initial comparison value is 0, so the first data from the file will be greater than this. Using an initial -1 value ensures that the needed adjustment is factored in.
The introduction of a three value sliding window makes this a little trickier. I chose to use only a single accumulator variable, keeping the values for the window and the latest sum on the stack.
I use reorder to update the stack orderings when adjusting the values for the sliding window and when moving the newest sum to the bottom.
I'm using the same trick with a negative starting value (-3 in this case) for my count, to allow for the initial non-existant entries of zero.