FVXX20 KWBC 171405 . VOLCANIC ASH ADVISORY STATEMENT ISSUED 1405 UTC 17 DEC 1999 BY THE WASHINGTON VAAC . GUAGUA PICHINCHA 99-155 ECUADOR 0.17S 78.60W . BACKGROUND: GUAGUA PICHINCHA ECUADOR (1502-02) SUMMIT HEIGHT 15695 FT (4784 M) . SOURCES OF INFORMATION: THE GEOPHYSICAL INSTITUTE IN ECUADOR...QUITO SURFACE OBSERVATION... U.S. NUMERICAL MODEL WIND FORECAST. . ERUPTION DETAILS: EXPLOSION AT 17/1250 UTC. . DETAILS OF ASH CLOUD: THE GEOPHYSICAL INSTITUTE IN ECUADOR REPORTED AN EXPLOSIVE ERUPTION WITH ASH ESTIMATED BETWEEN FL200 AND FL250. THE COLUMN OF ASH IS MOSTLY VERTICAL BECAUSE OF LIGHT WINDS. NO SATELLITE IMAGERY IS AVAILABLE AT THIS TIME BECAUSE OF RSO. . TRAJECTORY: UPPER AIR PATTERN AND NUMERICAL GUIDANCE SUGGEST ASH AT FL250 WOULD MOVE WESTWARD. . 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 AS SOON AS SATELLITE IMAGERY IS RECEIVED. . PLEASE REFER TO SIGMETS FOR CURRENT WARNINGS. . BROWN . NNNN