FVXX27 KNES 171628 VA ADVISORY DTG: 20171017/1628Z VAAC: WASHINGTON VOLCANO: USER MESSAGE PSN: XX AREA: XX RMK: THE 557TH WEATHER WING IS ISSUING THIS MESSAGE ON BEHALF OF THE WASHINGTON VAAC. 557 WW AND THE WASHINGTON VAAC ARE CONDUCTING A COORDINATED OPERATIONAL BACKUP TEST FROM 17/1625Z - 17/2000Z. PLEASE BE AWARE THAT 557 WW WILL ISSUE ANY NECESSARY VOLCANIC ASH ADVISORIES ON BEHALF OF THE WASHINGTON VAAC DURING THIS TIME FRAME. NNNN