FVXX21 KWBC 291850 VOLCANIC ASH ADVISORY STATEMENT ISSUED 1850 UTC 29 DEC 1999 BY THE WASHINGTON VAAC . TUNGURAHUA 99-311 ECUADOR 1.47S 78.44W . BACKGROUND: TUNGURAHUA ECUADOR (1502-08) SUMMIT HEIGHT 16480 FT (5023 M) . SOURCES OF INFORMATION: GOES-8 VISIBLE INFRARED AND MULTISPECTRAL IMAGERY...GEOPHYSICAL INSTITUTE IN QUITO...UPPER-AIR SOUNDING DATA...GUAYAQUIL MWO SIGMET...AIRCRAFT REPORT... . ERUPTION DETAILS: INTERMITTENT ASH AND STEAM EMISSIONS... . DETAILS OF ASH: SATELLITE IMAGERY THROUGH 29/1815 UTC DOES NOT SHOW ANY ASH OVER OR ADJACENT TO THE SUMMIT. HOWEVER THERE IS AN ABUNDANCE OF SHOWER AND THUNDERSTORM ACTIVITY JUST EAST OF THE SUMMIT WHICH IS SHROUDING THE REGION IN MULTILAYERED CLOUDINESS. THIS IS MAKING IT VERY TOUGH TO SEE WHAT IS OCCURRING AT THE SUMMIT LEVEL. IT IS POSSIBLE IN THIS SITUATION FOR ASH TO BE EMBEDDED WITHIN THE CLOUD DECKS AND GO UNDETECTED. SMALL ERUPTIONS HAVE BEEN REPORTED ON A DAILY BASIS WHICH HAVE PRODUCED ASH AND SO EXTREME CAUTION IS SUGGESTED. ASH AND STEAM SEVERAL HOURS AGO WAS NOTED TO BE REACHING FL230. . TRAJECTORY: ASH AND STEAM REACHING FL230 SHOULD MOVE SOUTHWEST AT ABOUT 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. . 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 30/0100 UTC. . PLEASE REFER TO SIGMETS FOR CURRENT WARNINGS. . ORRISON . NNNN