Noel’s solution will certainly work for you as long as you don’t need to manually alter the Percentage (because it’s now a Formula field). The are some choices you could make here:
The simplest would be a slight modification of the above - have a calculated % Chance field which uses a formula to take the manually entered % unless the Status = Awarded:
Another option, which I’ve often used in CRM type applications, is to have a table containing your Sales Statuses and for this table to hold a % Chance of winning associated with each Status. This approach kind of normalises your forecasting of your sales:
Then in this case, the % on your forecasting project table is actually a lookup from the Sales Statuses table:
I hope this helps!