FVXX21 KWBC 181245 . CORRECTION TO TRAJECTORY WIND SPEED . VOLCANIC ASH ADVISORY STATEMENT ISSUED 1245 UTC 18 MAR 1999 BY THE WASHINGTON VAAC . POPOCATEPETL 99-024 MEXICO 19.02N 98.62W . BACKGROUND: POPOCATEPETL MEXICO (1401-09) SUMMIT HEIGHT 17930 FT (5465 M) . SOURCES OF INFORMATION: GOES-8 INFRARED AND MULTISPECTRAL IMAGERY. MEXICO CITY UPPER AIR SOUNDING. MWO REPORT. . ERUPTION DETAILS: ERUPTION OCCURRED AROUND 18/1130 UTC . DETAILS OF ASH CLOUD: GOES 8 IMAGERY THROUGH 1145 UTC INDICATES A PLUME OF ASH EMANATING FROM POPOCATEPETL. ASH ESTIMATED BETWEEN FL350 AND FL400 IS 30KM (16NMI) WIDE AND EXTENDS FROM 19.04N 98.58W TO 19.32N 98.14W. . TRAJECTORY: 0000 UTC MEXICO CITY SOUNDING SUGGESTS ASH BETWEEN FL350 AND FL400 WOULD MOVE TOWARD THE NORTHEAST AT 65 TO 70KTS. . 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/messages.html (all lower case except /VAAC/) . OUTLOOK: SEE SIGMETS AND VAFTAD. . THE NEXT MESSAGE WILL BE ISSUED AT 18/1900 UTC. . PLEASE REFER TO SIGMETS FOR CURRENT WARNINGS. . NNNN