FVXX21 KWBC 251800 VOLCANIC ASH ADVISORY STATEMENT ISSUED 1800 UTC 25 APR 2000 BY THE WASHINGTON VAAC . TUNGURAHUA 00-486 ECUADOR 0128S 7826W . BACKGROUND: TUNGURAHUA ECUADOR (1502-08) SUMMIT HEIGHT 16480 FT (5023 M) . SOURCES OF INFORMATION: GOES-8 VISIBLE...INFRARED AND MULTISPECTRAL IMAGERY. UPPER WINDS FORECAST FROM THE AVIATION MODEL. THE GEOPHYSICAL INSTITUTE IN QUITO. . ERUPTION DETAILS: OCCASIONAL GAS AND ASH EMISSIONS. . DETAILS OF ASH: GOES-8 IMAGERY THROUGH 1615 UTC SHOWS LOW AND MID LEVEL CLOUDS OVER THE VOLCANO. AN OCCASIONAL PLUME OF ASH IS DETECTED IN THE VISIBLE IMAGERY EXTENDING TO THE WEST OF THE VOLCANO. THE ASH IS ESTIMATED AT FL250. THE GEOPHYSICAL INSTITUTE REPORTS THAT SEISMIC LEVELS HAVE BEEN NORMAL BUT THERE HAS BEEN SOME SMALL ASH EMISSIONS IN THE PAST 24 HOURS. TUNGURAHUA REMAINS IN A VERY ACTIVE STATE AND COULD PRODUCE AN ERUPTION AT ANYTIME. GOES-8 WILL BE IN A RAPID SCAN MODE FROM 1626 TO 2026 UTC TO SUPPORT NASA OPERATIONS. . TRAJECTORY: UPPER AIR PATTERNS SUGGEST ANY ASH UP TO FL250 WOULD MOVE TO THE WEST AT 10 TO 15 KNOTS. . OUTLOOK: SEE SIGMETS. . THE NEXT STATEMENT WILL BE ISSUED BY 26/0000 UTC. . REAL TIME SATELLITE IMAGERY ALONG WITH THIS AND OTHER VOLCANIC ASH ADVISORY STATEMENTS OFTEN ACCOMPANIED BY A MAP DEPICTING ASH LOCATION ARE AVAILABLE AT INTERNET URL ADDRESS http://www.ssd.noaa.gov/VAAC/washington.html (all lower case except /VAAC/) . PLEASE REFER TO SIGMETS FOR CURRENT WARNINGS. . KARST . NNNN