Complex sentence: A propitious upper-level environment allowed convection to improve, and late on June 1 the system developed to the extent that the India Meteorological Department (IMD) classified it a depression.
Split into simpler sentences: A propitious upper-level environment allowed convection to improve, and on June 1 a low-level circulation formed. By late on June 1, the system developed to the extent that the India Meteorological Department (IMD) classified it a depression.