FVXX21 KWBC 200200 . VOLCANIC ASH ADVISORY STATEMENT ISSUED 0200 UTC 20 NOV 1999 BY THE WASHINGTON VAAC . TUNGURAHUA 99-142 ECUADOR 1.47S 78.44W . BACKGROUND: TUNGURAHUA ECUADOR (1502-08) SUMMIT HEIGHT 16480 FT (5023 M) . SOURCES OF INFORMATION: GOES-8 VISIBLE INFRARED AND MULTISPECTRAL IMAGERY. UPPER-AIR DATA AND REPORTS FROM THE GEOFISICO INSTITUTO...GUAYAQUIL METEOROLOGICAL WATCH OFFICE. . ERUPTION DETAILS: CONTINUOUS STEAM AND ASH EMISSIONS. . DETAILS OF ASH: THE QUAYAQUIL MWO IS INDICATING THAT ACTIVITY HAS INCREASED AT THE TUNGURAHUA VOLCANO. THEIR LATEST SIGMET INDICATES THAT ASH IS REACHING FL350. HOWEVER THEIR ARE NO SIGNS OF THIS ASH IN ANY CHANNEL OF SATELLITE IMAGERY THROUGH 02/0115 UTC. TUNGURAHUA AND THE ADJACENT LAND AREAS HAVE SEEN A LARGE DEGREE OF SHOWER AND THUNDERSTORM ACTIVITY THIS AFTERNOON AND THIS EVENING AND CONSEQUENTLY THERE IS A LOT OF MULTILAYERED CLOUDS LEFT BEHIND. SO THE ASH THAT IS BEING REPORTED IS QUITE LIKELY EMBEDDED WITHIN THE MULTILAYERED CLOUD DECKS AND MAKES IT VERY DIFFICULT TO DETECT IN SATELLITE IMAGERY. EXTREME CAUTION IS ADVISED. . TRAJECTORY: ASH FROM THE SUMMIT TO FL250 IS MOVING TO THE WEST AT 10 KNOTS. ASH BETWEEN FL250 AND FL350 IS REPORTED TO BE MOVING TO THE WEST-SOUTHWEST AT 15 TO 25 KNOTS. THE UPPER-AIR WIND FORECASTS FROM THE 1200 UTC AVIATION MODEL DUE SUPPORT THE HEIGHT AND MOVEMENT ASSESSMENTS. . 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/) . OUTLOOK: SEE SIGMETS AND VAFTAD. . THE NEXT STATEMENT WILL BE ISSUED BY 20/0600 UTC. . PLEASE REFER TO SIGMETS FOR CURRENT WARNINGS. . ORRISON . NNNN