FVXX20 KWBC 060830 . VOLCANIC ASH ADVISORY STATEMENT ISSUED 0830 UTC 06 OCTOBER 1999 BY THE WASHINGTON VAAC . GUAGUA PICHINCHA 99-029 ECUADOR 0.17S 78.60W . BACKGROUND: GUAGUA PICHINCHA (1502-02) SUMMIT HEIGHT 15,695FT (4784 M) . SOURCES OF INFORMATION: GOES-8 INFRARED AND MULTISPECTRAL IMAGERY THROUGH 0745 UTC...QUITO SURFACE OBSERVATIONS...VAFTAD AND AN EXPERIMENTAL ASH TRAJECTORY MODEL...1200 UTC NUMERICAL WEATHER MODEL DATA . ERUPTION DETAILS: ERUPTION OCCURRED AROUND 05/1915 UTC. DETAILS OF ASH CLOUD: DUE TO DENSE METEOROLOGICAL CLOUDS OVER MOST OF ECUADOR ASH CANNOT BE DISCERNED IN SATELLITE IMAGERY. SURFACE OBSERVATIONS FROM QUITO CONTINUE TO REPORT ASH OVER THE STATION. THE VAFTAD WHICH IS A COMPUTER MODEL OF ASH TRAJECTORY SUGGESTS TWO AREAS OF PARTICULARLY DENSE ASH. ONE AREA IS ALONG THE NORTHEAST BORDER OF ECUADOR AND THE OTHER IS OVER THE PACIFIC OCEAN JUST WEST OF THE COAST OF ECUADOR. IT IS DIFFICULT TO DETERMINE THE HEIGHT OF THE ASH SINCE THE ASH IS OBSCURED IN SATELLITE IMAGERY BUT A COMPUTER MODEL SUGGESTS THAT THE ASH HEIGHT WILL NOT BE DECREASING TOO QUICKLY. ON THE OTHER HAND ASH WHICH CLEARLY OVERSHOOTS THE EXISTING THUNDERSTORMS IS NO LONGER SEEN. CONSIDERING THESE FACTORS ASH TO THE WEST OF THE VOLCANO IS VERY ROUGHLY ESTIMATED TO BE UP TO FL380 AND ASH TO THE EAST OF THE VOLCANO IS ESTIMATED TO BE UP TO FL550. . TRAJECTORY: UPPER AIR PATTERNS SUGGEST THAT ASH AT ABOUT FL380 WILL MOVE TOWARD THE WEST AT ABOUT 20 KNOTS. ASH AT ABOUT FL550 WILL MOVE TO THE EAST AT ABOUT 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 www.ssd.noaa.gov/VAAC/washington.html (all lower case except /VAAC/) . OUTLOOK: SEE SIGMETS AND VAFTAD. . THE NEXT STATEMENT WILL BE ISSUED BY 06/1430 UTC. . PLEASE REFER TO SIGMETS FOR CURRENT WARNINGS. . NNNN