I do not practice law in your state but here in California, whether you have to appear or not really depends on who is issuing the subpoena. If it is a defense counsel's subpoena, phone calling the attorney may allow you to make alternative arrangements since you will be out of town.
However, from your description of things, it appears that the prosecutor served you and so if you want to avoid any problems, you will have to make yourself available for the date on the subpoena. Once there, you may be able to explain to the prosecutor and the court why alternative arrangments in terms of scheduling might be necessary but if you want to avoid the possibility of the court issuing a warrant, you really should appear.
DISCLAIMER: This does not constitute legal advice but is merely general information based on a hypothetical.