At that point Essex looked in a strong position despite the early loss of England captain Alastair Cook at Old Trafford.
Cook added just three to his overnight 57 before falling to Kyle Hogg, but at lunch on day three they were 252 ahead on 203 for three, with Jaik Mickleburgh (53no) and Mark Pettini (36no) were building a damaging partnership.
At Bristol, Jimmy Adams provided the backbone of Hampshire's innings against Gloucestershire before they also saw two sessions washed out.
Resuming on 165 for eight, Adams and Danny Briggs added 60 runs before the latter fell for a hard-fought 54.
Adams continued along to 129no, including 14 fours and a six, as last man James Tomlinson faced 47 balls for just one run in support.
There was slightly more play between Worcestershire and Leicestershire at New Road but it was still a heavily curtailed second day.
Foxes spinner Jigar Naik took all four wickets to finish with five for 98 in Worcestershire's 294 for seven.
Former Sri Lanka batsman Thilan Samaraweera stood firm, though, and will resume on 92no.