Averaging every 48 cells of only positive values

I can easily average up the 48 rows that are positive with something simple like =AVERAGEIF(D1:D48,">0",D1:D48). However I want it to work like my just normal average formula worked which was =AVERAGE(OFFSET(D$1, 48 * (ROW() - 1), 0, 48)) because i have 17,520 cells in the row to calculate the average of every 48 cells only positive numbers. Any ideas or formulas that would work?

That worked beautifully! I couldn't figure out how to tie the codes together, thank you so much!