Jordan has been impressed with Dowie's record at Oldham. With little money to spend Dowie, who took over in May 2002, took the club into the Second Division play-offs last season where they lost 2-1 on aggregate to QPR.
Dowie played for Luton, West Ham, Southampton, Palace and Queens Park Rangers and won 59 caps for Northern Ireland.
The news will be a bitter disappointment for Symons, who had not been told last night of Dowie's imminent arrival. The caretaker manager was initially given a month to press his case for the job following the dismissal of Steve Kember.
After an impressive start, Palace suffered what Symons described as "a bad week at the office". They lost 3-0 to Aston Villa in the Carling Cup, 4-1 at Preston (where Symons was sent off) and 3-2 at home to Crewe - results which clearly did his case irreparable harm.
He is set to remain in charge for tomorrow's match at Reading but cannot play as he is suspended after his recent red card.
Jordan has parted company with Steve Coppell, Alan Smith, Steve Bruce, Trevor Francis and Kember since buying the club for £10million in May 2000. "If you look at my track record, I am very committed to my managers," he has said in the past.