FVXX21 KWBC 031331 . VOLCANIC ASH ADVISORY STATEMENT ISSUED 1330 UTC 03 DEC 1999 BY THE WASHINGTON VAAC . TUNGURAHUA 99-199 ECUADOR 1.47S 78.44W . BACKGROUND: TUNGURAHUA ECUADOR (1502-08) SUMMIT HEIGHT 16480 FT (5023 M) . SOURCES OF INFORMATION: GOES-8 VISIBLE..MULTISPECTRAL AND INFRARED IMAGERY. AVIATION MODEL WIND FORECAST. . ERUPTION DETAILS: CONTINUOUS STEAM AND ASH EMISSIONS AND OCCASIONAL EXPLOSIONS OF ASH. . DETAILS OF ASH: THE VOLCANO HAS SHIFTED INTO A RELATIVELY QUIET STAGE IN THE PAST SEVERAL DAYS. NO ASH CAN BE SEEN IN SATELLITE IMAGERY THROUGH 03/1245 UTC. HOWEVER...THE VOLCANO REMAINS IN AN UNSTABLE STATE AND COULD PRODUCE A MODERATE TO LARGE ERUPTION AT ANYTIME. . TRAJECTORY: UPPER AIR PATTERNS BASED ON NUMERICAL GUIDANCE SUGGEST ANY ASH FROM THE SUMMIT UP TO FL300 WOULD MOVE WEST-SOUTHWEST AT 10 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. . WALTER/NOAA/NESDIS/SAB . 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 03/1930 UTC. . PLEASE REFER TO SIGMETS FOR CURRENT WARNINGS. . NNNN