TgO Gen2:6 :וַעֲנָנָא הֲוָה סָלֵיק עַל אַרעָא וֻמַשקֵי יָת כָל אַפֵי אֲדַמתָא‏ : the cloud would go up over the earth and water the whole surface of the ground
See the entire entry for hwy vb. to be, to become