Complex sentence: Debby then moved westward where it encountered strong wind shear which prevented the storm from strengtening further and by September 10, Debbys winds flucuated as it passed through the Leeward Islands.
Split into simpler sentences: Debby then moved westward where it encountered strong wind shear which prevented the storm from strengtening further. On September 10, Debby's winds fluctuated as it passed through the Leeward Islands.