FVXX21 KWBC 0090500 . VOLCANIC ASH ADVISORY STATEMENT ISSUED 0500 UTC 09 DEC 1999 BY THE WASHINGTON VAAC . TUNGURAHUA 99-223 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... . ERUPTION DETAILS: CONTINUOUS EMISSION OF ASH AND STEAM....SHOWING SIGNS OF WEAKENING AND GRADUALLY BECOMING INTERMITTENT... . DETAILS OF ASH: INFRARED AND MULTISPECTRAL SATELLITE IMAGERY THROUGH 09/0415 UTC DOES NOT INDICATE ANY ASH ALTHOUGH THERE IS EXTENSIVE METEOROLOGICAL CLOUDS IN THE AREA. HOWEVER THERE IS A HOT SPOT EVIDENT IN THE RECENT SHORTWAVE IMAGERY. 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. 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 NORTHWEST AT ABOUT 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 . 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 09/1100 UTC. . PLEASE REFER TO SIGMETS FOR CURRENT WARNINGS. . NNNN