McGrath is head coach of the 2017 county champions, who have started the current season with two wins, a draw and a defeat to sit fourth in the table, one place and four points behind undefeated Yorkshire.
“It will be good to see ‘Mags’ again and it’s sure to be a good game,” said Ballance.
“Essex have been a good side for the last few years and will pose a tough test.
“‘Mags’ was a big help to me when he played for Yorkshire; I probably had four or five years either watching him bat or batting with him, and he was a class player and also a great bloke too.
“I know a lot of the young lads who played with him learnt a lot from him, and I learnt a lot just from the way he went about his batting.
“He was very consistent, not just in the runs he scored, but also in the way that he practised and trained. I definitely got a lot from that.”
McGrath, 43, played 242 first-class matches for Yorkshire between 1995 and 2012, scoring 14,091 runs at an average of 37.47 with 34 hundreds.
He also hit 7,220 runs in 275 one-day games at 33.73 with seven centuries, plus 1,403 runs in 66 T20 matches at 28.63.
“We’ve played some good cricket so far this season,” Ballance added.
“To get a couple of wins and a couple of draws has been good, and if we can get our first innings batting right we’ll win a lot more games.”
Yorkshire (from): Ballance, Bess, Brook, Coad, Fraine, Kohler-Cadmore, Leaning, Lyth, Olivier, Patterson (captain), Pillans, Tattersall, Willey.