The head of any state department may issue an advance warrant on the request of any officer or employee for the purpose of defraying his or her anticipated reimbursable expenses while traveling on business of such state department away from his or her designated post of duty, except expenses in connection with the use of a personal automobile. The amount of such advance shall not exceed the amount of such reasonably anticipated expenses of the officer or employee to be necessarily incurred in the course of such business of the state for a period of not to exceed ninety days. Department heads shall establish written policies prescribing a reasonable amount for which such warrants may be written.