Strong tropospheric flow (80-100 knots at 500mb) around a large amplitude trough extending from California eastward to the Gulf of Mexico caused a large area of blowing dust across western Texas and northern Mexico. Blowing dust is common in this region whenever dry conditions persist and afternoon heating increases the planetary boundary layer depth high enough to mix momentum downward to the surface when the winds are sufficiently strong. The blowing dust can sometimes be a sign of severe weather further downwind if other atmospheric conditions are favorable.  On this day there was an outbreak of tornadoes in Arkansas, Louisiana and Mississippi. 

In Figure 1, GOES-10 channel 4 imagery shows the dust over western Texas and northern Mexico. Compare how quickly it took you to locate the dust by locating it in the GOES-10 IR 10.7 micrometer and 12.0 micrometer difference product (Figure 2).  The large negative difference is observed because the emissivity at 10.7 micrometers is less than the emissivity at 12.0 micrometers due to the properties of dust particles. The same idea is used to detect volcanic ash with this product. 

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