This loop of GOES-8 Sounder-derived Precipitable Water (PW) shows the moist nature of the air mass that was being advected northeastward into Arkansas and the southern Mississippi valley region on 21 January 1999. PW values of 35-40 mm (yellow to light red enhancement) were evident ocer much of the region. ETA model 850 hPa wind streamlines are plotted at 6-hour intervals on the imagery.