FVXX21 KWBC 080930 . VOLCANIC ASH ADVISORY STATEMENT ISSUED 0930 UTC 08 DEC 1999 BY THE WASHINGTON VAAC . TUNGURAHUA 99-220 ECUADOR 1.47S 78.44W . BACKGROUND: TUNGURAHUA ECUADOR (1502-08) SUMMIT HEIGHT 16480 FT (5023 M) . SOURCES OF INFORMATION: GOES-8 MULTISPECTRAL AND INFRARED IMAGERY. UPPER AIR DATA AND REPORTS FROM THE GEOPHYSICAL INSTITUTE. U.S. NATIONAL WEATHER SERVICE MODEL DATA. . ERUPTION DETAILS: CONTINUOUS EMISSION OF ASH AND STEAM....SHOWING SIGNS OF WEAKENING AND GRADUALLY BECOMING INTERMITTENT... . DETAILS OF ASH: SATELLITE IMAGERY THROUGH 08/0845 UTC DOES NOT SHOW ANY ASH ALTHOUGH THERE IS EXTENSIVE METEOROLOGICAL CLOUDS IN THE AREA. OVER THE LAST TWO WEEKS THERE HAS BEEN A NOTICEABLE DECREASE IN THE AMOUNT OF ASH RELEASED BY THE VOLCANO. THE GEOPHYSICAL INSTITUTE CONFIRMS AN OVERALL DECREASE IN THE NUMBER OF EXPLOSIONS. HOWEVER THE VOLCANO REMAINS VERY UNSTABLE AND THERE STILL IS VENTING OF ASH AND STEAM FROM THE SUMMIT ACCORDING TO THE INSTITUTE. ASH AND STEAM ARE ESTIMATED TO BE NEAR-SUMMIT AND REACHING AS HIGH AS FL180. . TRAJECTORY: ANY REMAINING ASH AND STEAM AT FL180 IS EXPECTED TO MOVE TO THE NORTH-NORTHWEST AT 15 TO 20 KNOTS. . 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. . EFFECTIVE JANUARY 3 2000 AT 0000 UTC... ALL REFERENCES TO LATITUDE AND LONGITUDE IN VOLCANIC ASH ADVISORY STATEMENTS WILL BE IN DEGREES AND MINUTES OF A DEGREE. EXAMPLE: 16.70N 62.20W WILL BE 1642N6212W . THE NEXT STATEMENT WILL BE ISSUED BY 08/1530 UTC. . PLEASE REFER TO SIGMETS FOR CURRENT WARNINGS. . NNNN