Weather systems (4)
I believe the answer is:
lows
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">weather systems</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for lows that I've seen before include "Moos" , "Depressions" , "Cyclones" , "Minimum levels" .)